Abstract:Soil-rock mixed engineering accumulation is a kind of dump, and secondary disaster caused by rain water is easy to occur because of its special material composition and structure. In recent years, more and more scholars have paid attention to the problem of slope soil erosion of it. However, there is no complete theory and method in the study, and the whole research is in the preliminary exploratory stage. In this paper, the research status of infiltration process, runoff hydrodynamic characteristics and sediment yield of the slope surface of soil-rock mixed engineering accumulation are reviewed. It is proposed that in the future's research, the method of element tracer can be used to explore the law of water migration in the soil-rock mixed engineering accumulation, and improve the research of water flow dynamics characteristics of the slope from the material sources, types and research methods, and pay attention to the discussion of the heap shape, the original appearance and the distribution of the gravel, as well as the influence of them on the erosion of slope soil and underground soil, meanwhile the erosion law of slope soil and underground soil under the combined action of rainfall and runoff should be emphasized, and this will be benefit to explore the water and sediment reduction effect of different control measures. Soil erosion prediction model suitable for all types of soil-rock mixed engineering accumulation should be constructed, which is the foundation of constructing ecological protection system and sustainable development of regional economy.

Abstract:Taking the typical slope of the Chongling Basin in the Taihang Mountain area as the research object, the dye tracer experiments with Blue-FCF and KI were performed. The image processing software was used to explore the changes of preferential flow morphological characteristics at the five different slope positions. The results showed that:(1) With the increase of altitude, the soil thickness and bulk density of each slope position gradually decreased, and the total porosity, permeability coefficient and saturated moisture content gradually increased, while the wilting coefficient and field water holding capacity tended to fluctuate. (2) With the rise of slope position, the depth of dye migration increased, the matrix area decreased and the preferential flow area gradually increased; the stained area rate of dye infiltrate decreased with the increase of the depth. The interaction between soil moisture and surrounding soil in the depth below 40cm was weaker than that in the lower slope; the volume of dye infiltration increased gradually as the rise of slope position; (3)As the slope position increased, the contribution of the preferential flow to the actual water transport increased and the water flow infiltrated with preferential flow as the main method on higher slope; (4) Soil texture and bulk density were the driving forces for the difference of preferential flow at different slope positions in earth-rock mountainous area.

Abstract:The convex hill slope was used as the object, using indoor runoff scouring experiments, the variation process of water erosion dynamics and variance of erosion sediment under different vegetation spatial configurations was studied. The results showed that the spatial variation of runoff velocity exhibited a fluctuating state, with first decreasing then increasing with distance between the hydraulic section and the slope top under bare-slope conditions. The most serious erosion was recorded on the upper part of the up slope and down slope. When the grass strip was planted at about 60%~80% of the up slope length, the impact on various runoff velocity was greater, and decreased by about 22%;by which water storage function is 12%, and sediment reduction function reach 69%. It could better exert soil and water conservation function by direct sediment interception and resulted in the lowest level of erosion in the experiment. The spatial variation trend of runoff and sediment was basically consistent with runoff velocity under different vegetation spatial configurations. With the increase of grass strip distance to the slope top, the runoff and sediment showed the first increasing then decreasing trend. The regulation effect of vegetation on erosion sediment transport was achieved through the regulation of the water erosion dynamic process. In the course of regulation, the vegetation spatial configuration altered spatiotemporal variation characteristics of runoff velocity, and thus played a significant effect on hydrological processes. The information of this study can be useful for better understanding the coupling relationship between vegetation, runoff scouring, and water erosion dynamics process.

Abstract:In this study, the unit slope-gully system was used as the object, using indoor simulated rainfall experiments, combined with three-dimensional laser scanning technology and micro topography analysis technology, the difference of erosion sediment under different grasss trip position was studied.The results showed that some rational grass strips(p<0.05) influenced both runoff and sediment yield in the slope-gully system. The regulation functions on runoff and sediment with the grass strip on the middle lower part of the slope were generally clearer than those with grass on the upper part of the slope. The optimal position for grass strips in the slope-gully system was identified as 60% of the slope length. In this location, the grass strips could effectively reduce the runoff and sediment by 7.35% and 62.93%, respectively. The water storage function of the grass strip was weak; however, its direct sediment interception function was more effective, the water and soil conservation function was optimal.When grass strip was planted in the lower part of the slope, the severity of erosion sediment transport processes was eased, and the effect of grass strip on erosion was reflected.When grass strip was planted in the middle lower part of the slope, only 52% of the underlying surface was eroded,the severity of erosion sediment transport processes was eased significantly, the regulation of vegetatione ectively controlled the erosion formation and development.When grass strip was planted in the middle part and middle upper part of the slope, extremely aggravated erosion development.The information of this study can be useful for better understanding the optimal vegetation pattern.

Abstract:The study took down slope ridge planting, flat planting, and cross ridge planting as the study object, studied the characteristics of surface runoff, interflow and nitrogen loss under natural rainfall conditions in the yellow soil area, and intended to provide the theoretical basis for predicting and preventing nitrogen loss. The results showed that:The average surface runoff at maize mature stages was 7.96 times and 8.22 times higher than the interflow in 0-20 cm and 20-40 cm soil depths under the conditions of natural rainfall. The surface runoff and nitrogen loss were significantly different under different tillage measures. The surface runoff and nitrogen loss were in order of down slope ridge planting > flat planting > cross ridge planting. The surface runoff of down slope ridge planting was 1.20 times and 2.07 times higher than that of flat and cross ridges planting respectively. Nitrogen loss in down slope ridge planting was 1.35 times and 2.06 times higher than that of flat and cross ridge planting. Under cross ridge planting, the interflow and nitrogen loss of the 0-20 cm and 20-40 cm soil depths were significantly higher, and nitrogen loss in 0-20 cm soil depths was 2.45 times and 1.90 times higher than that of down slope ridge and flat planting respectively, while nitrogen loss in the 20-40 cm soil depths was 2.34 times and 1.79 times higher than that of down slope ridge and flat planting respectively. Surface runoff was the main channel for nitrogen loss. The dissolved nitrogen accounted for 63.84%~72.61% of the total nitrogen loss, and was the main form of nitrogen loss. Nitrate nitrogen accounted for 16.47%~59.17% of the total nitrogen loss, and was the main form of inorganic nitrogen loss. There were significant linear positive correlations between nitrogen loss and runoff, rainfall. Cross ridge planting was an effective way to decrease nitrogen loss under the condition of natural rainfall and reasonable tillage measure can protect water and soil resources and prevent nitrogen loss in the study region.

Abstract:Aiming at the serious problem of water and soil loss of the yellow fluvo-aquic soil in the Huaibei Plain, in order to reveal the law of runoff and sediment yield,the large artificial simulated rainfall runoff test field of Wudaogou Hydrological Experimental Station was used to carry out three rain intensity of 40, 60, 80 mm/h and threeslope gradients of 5°, 10°, 15° runoff and sediment production simulation.The results showed that the initial runoff time of the slope is shortened with the increase of slope and rain intensity.It is less obvious with the increase of rain intensity and slope.The turning point of the runoff and sediment yield per unit time with the change of rainfall time is 6~15 min after the runoff.The change of production flow per unit time with the change of rainfall time showed a rapid increase in the early stage, a slow increase in the medium term, and a stable period in the later period.The 40, 60 mm/h rain intensity per unit time flow rate decreased with the increase of the slope, however, the rain intensity increased with the increase of slope with 80 mm/h. The sediment yield per unit time increased with the increase of rain intensity and slope.The cumulative sediment yield and yield of different slopes showed a power or linear function with the change of rainfall time (R²>0.99). The effects of slope and rainfall intensity on runoff and total sediment yield were multivariate linear and multivariate power functionsrelationship.

Abstract:In order to effectively prevent and control nitrogen loss in the growth stages of maize in the purple soil area during rill erosion stage, the soil erosion and nitrogen loss was studied. The artificial simulated rainfall combined with field runoff plot experiments were used to study the characteristics of nitrogen loss, including surface runoff, interflow and sediment yield, soil flow and erosion sediment, in the whole stages of maize during rill erosion stage under the rainfall intensity of 1.5 mm/min. The results showed that surface runoff, interflow and sediment yield were increased first with rainfall duration, and the values tended to peak during maize growth stages at rill erosion. Total nitrogen, soluble total nitrogen, nitrate and sediment yield in surface runoff showed an overall trend of first increase and then stability, while ammonium nitrogen loss showed volatility in the early rain period and became steady gradually with rainfall duration. The total nitrogen losses in surface runoff were the highest at seedling stage of maize, and the maximum was 628.77 mg/m². The total nitrogen losses in interflow were the highest at jointing stage and tasseling stage of maize. The total nitrogen losses in sediment yield were the highest at seedling stage of maize, and the maximum was 144.95 mg/m².Interflow were the main channels for nitrogen losses, and nitrate nitrogen was the main form of nitrogen loss during the rainfall process.

Abstract:The effects of reduced nitrogen application and straw deep buried on soil electrical conductivity, yield of maize and residuals of soil nitrate nitrogen were researched through field experiment conducted in spring maize planted with semi-plastic film in the Changwu State Key Agro-Ecological Station, and aimed to provide theoretical support for improving the efficiency of nitrogen use and protecting the environment. The experiment included five treatments with three replicates, no nitrogen fertilization application (CK), conventional nitrogen fertilization application (CON1, N 250 kg/hm²), conventional nitrogen fertilization plus straw (CON2, N 250 kg/hm²), reduced nitrogen fertilization application (CR1, N 200 kg/hm²), and reduced nitrogen fertilization application plus straw (CR2, N 200 kg/hm²). The soil electrical conductivity at different growth stages of spring maize was investigated, and the soil nitrate nitrogen content and spring maize yield during the harvest period were measured. The results showed that:the peak values of soil electrical conductivity at the stages of maize tillering and jointing appeared at the soil profile of 40-150 cm, at the stages of maize heading and maturing the peak values of soil electrical conductivity appeared at the soil profile of 40-200 cm, and the range of peak value moved down. In the 0-150 cm soil profile, the soil electrical conductivity followed the order of CON2 > CON1, CR2 > CR1. In the 0-150 cm soil layer, the soil electrical conductivity of conventional nitrogen application was higher than those of reduced nitrogen application treatments. Compared with the traditional nitrogen fertilization application, the reduced nitrogen application reduced the nitrate nitrogen content in the soil profile. At the same time, deep buried straw could also reduce the nitrate nitrogen content in the soil profile and postpone the soil nitrate nitrogen leaching. Compared with the traditional nitrogen application, 20% reduction of nitrogen fertilization could increase the maize yield by 9.59%. On the condition of nitrogen application, deep burying of straw was beneficial to increase crop yield and the potential of nitrogen production. Straw deep burying was beneficial to improve soil electrical conductivity, reduce soil nitrate nitrogen content, control soil nitrate nitrogen leaching and increase corn yield.

Abstract:Subsoiling and straw mulching are widely used in mechanized agriculture. The research objective was to identify the characteristics of soil and nutrients loss under subsoiling and straw mulching in purple soil slope cropland. Nine experimental treatments, which included the conventional flat cultivation, ridge cultivation, subsoiling, full straw mulching and pulverized straw mulching, were conducted in runoff plots. The yield, surface runoff, subsurface flow, and nutrients contents were measured in the two-year trial. The research results are shown in follow:(1) Compared with flat planting, subsoiling significantly increased the subsurface flow and nitrogen concentration in the flow, increased total runoff by 39.6%, and increased the nitrogen loss in runoff by 85%, and the maize yields were decreased. (2) Straw mulching decreased surface runoff, increased subsurface flow and nitrogen concentration in the flow, increased the total runoff by 6.4%. Increased the total nitrogen loss by 9.4% and had no significant effect on maize yield. (3) The nitrogen concentration in surface runoff was 43.2% in pulverized straw mulching treatments, less than the full straw mulching treatments. There were no significant differences in the surface runoff, subsurface flow and nitrogen concentrations in the flow between the two straw mulching treatments. (4) Subsoilling+ridge treatment had the highest nutrient loss, but the lowest yield in all the treatments. So this tillage method was not applicable in the purples soil of slope cropland. The findings in this were useful for assessing the feasibility about subsoiling and straw mulching in purple soil slope cropland.

Abstract:In Shapotou districts of southeastTengger Desert, we selected the flow sand, 4 and 30 years sand fixing areas within straw checkerboard as the research plots to study the soil properties and fractal characteristics during the process of forestation and sand fixation by straw checkerboard across seasons. The results showed that:(1) Soil moisture content and soil pH were affected by both timing of sand fixation and seasonal variations. (2)Soil electrical conductivity of the flow sand, the 4 year and the 30 years sand fixing vegetation area was 77.84~82.34, 86.04~114.68 and 113.80~168.66 μS/m, respectively, and soil organic carbon of the three kinds of plots was 0.86~1.74, 1.30~1.52 and 7.96~17.36 g/kg, respectively, and soil total nitrogen was 0.18~0.32, 0.24~0.26, and 0.44~0.78 g/kg, respectively.(3) Coarse sand was found only in the flow sand, and the content was 0.50%~0.53%. Medium sand content of the flow sand, the 4 year and the 30 years sand fixing vegetation area was 40.42%~43.82%, 14.36%~17.17% and 12.01%~14.75%, respectively, and fine sand content was 55.44%~58.84%, 80.15%~83.19% and 42.55%~53.30%, respectively, and very find sand was 0.24%~0.31%, 2.45%~3.33% and 15.85%~21.35%, respectively. Clay and silt were found in the 30 years sand fixing vegetation area, and the content was 0.84%~1.33% and 15.16%~22.75%, respectively. (4) There was a negative correlation between coarse sand and soil electrical conductivity(P<0.05), and fine sand and medium sand both showed significant negative correlation with electrical conductivity, organic carbon, total nitrogen and carbon-nitrogen ratio(P<0.01). Clay, silt and very fine sand all showed significant positive correlation with soil electrical conductivity, organic carbon, total nitrogen and carbon-nitrogen ratio(P<0.01). (5)The soil fractal dimension was 0~3, soil fractal dimensionof the flow sand, the 4 year and the 30 years sand fixing vegetation area was 0.55~0.82,1.57~1.67 and 2.37~2.59, respectively. (6)There was a negative correlation between soil fractal dimension and coarse sand, medium sand(P<0.05), which had significant positive correlation with clay, silt, and very fine sand (P<0.01), but had no correlation with soil fine sand (P>0.05). It was concluded that the stabilization of flows and by straw checkerboard and artificial forestation and sand fixation in southeast Tengger Desert could improve soil texture, promotethe better development of soil physical-chemical properties and the improvement of soil quality, and prevent and control desertification.

Abstract:The effect of hydroxypropyl methyl cellulose (HPMC) on soil water movement and soil water stability aggregates was studied by applying different content of HPMC into soil. The results showed that:(1) The infiltration capacity of soil was significantly reduced by a certain amount of HPMC in soil, and the cumulative infiltration, wetting front migration distance and infiltration rate decreased significantly with the increase of HPMC in the range of 0~1.0 g/kg. The measured data fitted with the Philip formula and the Kostiakov formula respectively, and two formula could well simulate the infiltration process of the soil after the application of HPMC. With the increase of HPMC content, the infiltration rate S, the stable infiltration rate A and the empirical coefficient K decreased obviously, and the empirical index beta gradually increased. (2) With the increase of HPMC content, the percentage of water stable large aggregate of >0.25 mm increased obviously, the fractal dimension of the tested soil decreased gradually, and the average weight diameter of the soil showed a significant positive correlation with the content of water stable. This indicated that after HPMC application, the soil structure was more stable, and its ability of anti-destruction and erosion resistance was enhanced. In conclusion, HPMC has obvious effect on reducing permeability after adding into the soil, and to a certain extent, it can improve soil structure and improve soil erosion resistance.

Abstract:In order to obtain a high-yield, high-efficiency and high-quality cultivation technique, this study was carried out to research the effects of film mulching period and nitrogen application rate on the soil water consumption characteristics, grain yield and quality of spring maize in dry lands of eastern Gansu province of China. The field experiment used a split-plot design. The main plot treatment was film mulching period. There were two levels of film mulching in autumn (mulching in farm slack season) and in spring (film mulching before seeding). The subplot treatment was nitrogen application rates, which include seven levels of nitrogen, 0 kg/hm² (CK), 75 kg/hm² (N75), 150 kg/hm² (N150), 225 kg/hm² (N225), 300 kg/hm² (N300), 375 kg/hm² (N375), and 450 kg/hm² (N450). The 0-300 cm soil moisture content of autumn time and spring maize season, yield traits, dry matter accumulation and grain quality were measured. The results showed that:(1) Compared with film mulching in spring, film mulching in autumn significantly increases the soil water storage by 54.0~97.7 mm at 0-200 cm depth, and by 53.9~108.8 mm in 0-300 cm depth. (2) Long-term nitrogen application significantly reduced soil water storage at 0-300 cm during each growth period compared with CK. (3) Compared with the no film mulching, film mulching in autumn significantly reduced soil water consumption by 47.2~55.7 mm. (4) The water consumption was higher at middle maize growth stage than at early stage and late stage. The total water consumption of maize in the whole growth stage was 38.6~86.7 mm higher in autumn mulching than in spring mulching. This was closely related to soil water content before seeding. (5) The highest grain yield and water use efficiency was in treatment N225 kg/hm². The average grain yield of different N application treatments in autumn mulching was 5.2% higher than that of spring mulching. The pure N225 kg/hm² treatment also had the highest dry matter accumulation in different growth stages and harvest index. In addition, nitrogen application significantly affected crude protein, crude fat, and ash content. Therefore, the combination of film mulching in autumn and N 225 kg/hm² could significantly increase the yield and water use efficiency of spring maize, optimize the yield composition, and improve grain quality. It is a suitable planting mode for efficient and high-quality maize production in the drylands of the eastern Gansu Province.

Abstract:Field experiment of border irrigation of summer maize was conducted to analyze the effect of border fertigation model on crop growth as well as soil water and nitrogen, evaluate the irrigation fertilization quality and water using efficiency under different treatment, and investigate suitable model of border fertigation. Different border width, fertilization timing, and inflow cutoff were selected in the field experiment, and the optimum level combination of fertigation was selected by orthogonal design.The results showed that the influence of different treatment on storage efficiency of soil water and nitrogen are not significant, but the effect on soil nitrate uniformity is obvious and it is same to soil water. The storage efficiency of soil water (59%~63%) were lower than that of soil nitrogen (61%~64%) while the uniformity of soil water (95%~99%)were higher than that of soil nitrogen (85%~94%). The yield and water using efficiency were significant affected by border width, timing of fertilization and inflow cutoff. Considering all the indexes, the border fertigation model with the border width of 1.5 m, the inflow cutoff of 95%, and applying fertilizer as water advanced at 1/2 of the border length showed higher storage efficiency(63.36% and 64.01%) and uniformity (98.71% and 94.42%) of soil water and nitrogen, was benefit to form a uniform soil condition for crops absorption and uptake, and could achieve a higher yield (9 886.1 kg/hm²) and water using efficiency(2.62 kg/(hm²·mm)).

Abstract:To explore the effects of soil texture, soil temperature and bulk density on movement characteristics of upward capillary water flow of saline water in soil of northwest arid region, a lab simulation experiment was conducted in sandy loam and clay loam by HYDRUS-1D. The models of ground water recharge of capillary water with soil temperature and bulk density of were built. For sandy loam, the absolute coefficient was above 0.96, RMSE was less than 0.95 cm, and the maximum relative deviation between the calculated and simulated values was less than 11.9%, while the corresponding values were 0.96, 4.3 cm and less than 8.4% respectively in clay loam. The models of rising height of capillary water with soil temperature and bulk density were also built. For sandy loam, the absolute coefficient was above 0.996, RMSE was less than 2.7 cm and the maximum relative deviation between the calculated and simulated values was less than 8.37%, and the corresponding values were 0.997, less than 3.8 cm and less than 11.9% respectively for clay loam. The fitting degree of the model was good, and the equation established was in line with the actual situation. The salt contents of sandy loam mainly gathered at 1.70~2.20 m from the surface, while 0.3~1.3 m for clay loam. The distribution of soil salinity in sandy loam soil was significantly affected by soil temperature and bulk density, but only soil bulk density worked in clay loam and temperature had little effect. To summarize, these research results could provide scientific foundation for water and salt management in salinized area.

Abstract:The paper takeYunnan laterite as the object, soil-water characteristics under wet-dry cycle by the pressure plate method were explored, meanwhile, factors such as initial dry density(1.20, 1.25 and 1.30 g/cm³), initial moisture content(30.0%, 33.0% and 36.0%), pre-consolidation pressure(0, 50, 100 and 200 kPa), and particle size(0.5, 1.0 and 2.0 mm)were taken into considrearion. The results showed that laterite's matric suction decreased with increasing moisture content during the wet-dry cycle, and the soil-water characteristic curve was "inverted J". The soil-water characteristic curve could be divided into three stages, which included rapid dehydration, slow dehydration, and stable dehydration, and the corresponding moisture absorption process could also be divided into three stages:rapid moisture absorption, slow moisture absorption, and stable moisture absorption. Under the same matrix suction, laterite moisture content increased with the increase of initial dry density, initial moisture content and pre-consolidation pressure, while laterite moisture content decreased with the increase of particle size. Laterite soil-water characteristic curve could be fitted by power function, while initial dry density, pre-consolidation pressure, particle size (except 0.5 mm), and soil-water characteristic curve could be fitted with a linear function. The moisture content of the laterite dehumidification process was higher than that of the moisture absorption process. There was a hysteresis in the soil-water characteristic curve during the process of moisture removal and moisture absorption. It was ascribed to the effects of pore size, bottle neck, contact angle and cyclic expansion and shrinkage of laterite under wet and dry cycles.

Abstract:This study investigated soil and water conservation effect of different revegetation patterns in sandy-hilly region of northern Shanxi Province. The characteristics of soil water content, physical and chemical properties, runoff volume and soil erosion of four revegetation patterns plots which have been grown for about twenty years at sunny slope in Jiajiayao watershed in Youyu County, were analyzed. Those revegetation patterns included naturally colonized herbaceous plants, Pinus tabuliformis plantation, Caragana korshinskii plantation, and Pinus tabuliformis-Caragana korshinskii plantation. The results showed that:(1) There was no significant difference in soil water content in 0-100 cm depth. Soil bulk density of naturally colonized herbaceous plants and Pinus tabuliformis plantation were higher than those of Pinus tabuliformis-Caragana korshinskii plantation and Caragana korshinskii plantation, while the trends of soil total porosity were opposite to those of bulk density. (2) There were no significant differences in soil granularity distribution, pH, organic matter, ammonium nitrogen and available phosphorus in 0-20 cm depth of the four revegetation patterns, while the differences of nitrate nitrogen and available potassium were significant (P<0.05). (3) Revegetation patterns had significant differences on soil erosion,but no effects on runoff (P<0.05). The soil erosion of naturally colonized herbaceous plants and Pinus tabuliformis plantation were significantly higher than those of Caragana korshinskii plantation and Pinus tabuliformis-Caragana korshinskii plantation (P<0.05). (4) If coverage was similar, root density, near surface vegetation coverage and leaf litter thickness were the main factors affecting soil and water conservation effect of forest-grass vegetation.

Abstract:In order to investigate the effects of herbaceous roots on soil detachment in alluvial fan of benggang, Paspalumwettsteinii and Pennisetum sp. were chosen as the research objects, and an experiment was carried out using flow flumes with adjustable slope gradients to analyze the changing characteristics of soil detachment and their influencing factors. The results showed that the soil detachment rates of each soil layer were as follows:Bare land (69.93 g/(s·m²)) > Paspalumwettsteinii(57.42 g/(s·m²)) > Pennisetum sp.(43.28 g/(s·m²)), and the soil detachment rates increased with the increase of soil depth as a power function. The most important factor to characterize soil detachment was root length density, and the soil detachment rates of Paspalumwettsteinii plot declined as a logarithmic function with all root indexes, while a power function decline was observed for Pennisetum sp. plot, indicating the difference effects of root system configurations on soil detachment. Soil detachment of two kinds of grasslands could be estimated using flow shear stress, soil shear strength, and root length density (NSE ≥ 0.90). The results of this study could provide scientific evidences for the disposition of collapse management measures.

Abstract:In order to study the effects of different arrangement modes on shear strength of herbal root-soil composites, the difficulty that the same root amount or root number could not simultaneously satisfy different arrangement modes(square,quincunx and ring) was solved effectively.On this basis, by taking the soil and sedge family plants in the north side of north-south transition zone of china as the research object, the shear strength of herbal root-soil composites were researched. The strengthening effects of the herbal root-soil composites and the variation of shear strength index were analyzed by using laboratory test under the disturbance of different levels of root amount and arrangement modes. The results show that the shear strength and cohesion of root-soil composites increased with the root amount increasing under the same conditions. The friction angle of root-soil composites exhibits almost no variation with the root amount increasing under the same conditions. The shear strength of root-soil composites and the cohesion increased with the root diameter increasing.The friction angle of root-soil composites exhibits almost no variation with diameters increasing The arrangement modes of herbal root had little influence on the shear strength of root-soil composites when the normal stress was comparatively small.The influence on the shear strength of root-soil composites of the arrangement modes could not be ignored when the normal stress was comparatively big.Moreover, The bigger the area replacement ratio, the larger errors.The results also showed that it was considered that the square arrangement exerted an important influence on the cohesion and friction angle of root-soil composites when the area replacement ratio comparatively small.The influence on the cohesion and friction angle of root-soil composites were gradually stabilized with the increase of the area replacement ratio.

Abstract:In order to study and compare the mechanical properties of the single root and root-soil composite of Populus davidiana, Picea crassifolia, and Pinus tabuliformis, the single root tensile test, the triaxial compression test, and the saturated permeability test were used to get the mechanical properties and the soil-water characteristic curves of the three arbors. The results showed that there were significant differences in the mechanical properties of the single root of the three arbors, and the diameter had a significant effect on the mechanical properties of the single root. The maximum tensile force of the single root was correlated to the power function of diameter and increased with the increasing of diameter, while the tensile strength and the Young's modulus of single root were correlated with the logarithmic function of diameter and decreased with the increasing of diameter. The average of maximum tensile force of the single root of P. davidiana was 0.38 kN > P. crassifolia (0.25 kN) > P. tabuliformis (0.17 kN), the average of tensile strength of P. davidiana (33.39 MPa) > P. crassifolia (27.79 MPa) > P. tabuliformis (18.45 MPa), the average of Young's modulus of P. davidiana (0.17 GPa) > P. crassifolia (0.12 GPa) > P. tabuliformis (0.11 GPa). There were significant differences in the cohesion and the elastic modulus of the three arbors root-soil composite, but there was no significant difference in the friction angle (the mean value was 30.48°). The cohesion of root-soil composite of P. davidiana (10.65 kPa) > P. crassifolia (8.97 kPa) > P. tabuliformis (7.13 kPa), the elastic modulus of P. davidiana (2.17 MPa) < P. crassifolia (2.52 MPa) < P. tabuliformis (4.21 MPa). The soil-water characteristic curves (SWCC) and the permeability function curves of the root-soil composite of the three arbors were significantly different. The permeability of root-soil composite of P. davidiana was higher than that of P. tabulaeformis and P. crassifolia. The result is an important reference for evaluating the ability of the three arbors to stabilize the slope and establishing the numerical model of the slope stability analysis for Helan Mountain.

Abstract:Soil erosion is an important factor in destroying land resources in the Loess Plateau. In order to understand the current situation of soil erosion in Yangling District of the Loess Plateau, the temporal and spatial distributions of soil erosion were analyzed using GIS and RS techniques. T General Soil Loss Equation (USLE) was also used to evaluate the erosion intensity and its temporal and spatial variability. The results showed that the soil erosion in Yangling District was mainly dominated by slightly erosion and mild erosion. From 2010 to 2014, the proportion of soil erosion intensity was basically stable. The relationships between soil erosion and slope and elevation indicated that the gentle slope of less than 15° in Yangling District was dominated by slight and light erosion. With the increases of slope, the slight erosion decreased, and the ratios of strong, extremely intense and severe erosions increased. The areas of soil erosion intensity showed a trend of decreasing with the increase of elevation, and the peaks were mostly distributed in the 500~550 m elevation zone.

Abstract:In order to explore the mechanism of woody peat cultivation on the high-quality tillage layer in the newly cultivated land in red soil and the improvement effects of woody peat over other organic materials on the new cropland in red soil, a field experiment was conducted to study the effects of different organic materials addition on soil physicochemical properties, microbial biomass in 0-20 cm red soil of arid land and rice yield. Six different treatments included:CK (without adding modified material), M₃₀ FS (woody peat 30 t/hm²+straw decay 3 t/hm²+limestone powder 3.75 t/hm²), M₁₅ FS (woody peat 15 t/hm² +straw decay 3 t/hm²+limestone powder 3.75 t/hm²), CFS (biochar 15 t/hm²+straw decay 3 t/hm²+limestone powder 3.75 t/hm²), OFS (organic fertilizer 15 t/hm²+straw decay 3 t/hm²+limestone powder 3.75 t/hm²), FS (straw decay 3 t/hm²+limestone powder 3.75 t/hm²).The results showed that:(1) Compared with the control, the addition of woody peat and organic materials significantly reduced the soil bulk density in tillage layer, improved the soil total porosity and pH. Soil fertilities were also increased after addition of woody peat and organic materials with the varying degrees of improvement, the contents of soil organic matter, total nitrogen, total phosphorus and total potassium increased by 36.41% to 88.53%, 2.22% to 37.78%, 6.25% to 93.75% and 27.57% to 85.60%, respectively,and ammonium nitrogen, available phosphorus and available potassium increased by 17.21%~134.85%, 1.42%~72.76%, 8.71%~156.79% and 12.99%~332.39%, respectively.(2) Adding woody peat and organic materials had a significant effect on soil microbial biomass in tillage layer. Compared with the control, the soil microbial biomass carbon and nitrogen increased significantly by 52.95% to 219.00% and 121.45% to 548.73% respectively.(3) The rice yield increased significantly with the application of woody peat and organic materials, of which M₃₀ FS gave the biggest increase of 39.53% in production. (4)The soil quality of cultivated land under different treatment was divided into 3 grades by cluster analysis:first grade (M₃₀ FS), second grade (M₁₅ FS, OFS, CFS), and third grade (FS, CK), among which soil quality level was the highest under M₃₀ FS. The addition of woody peat and organic materials could significantly reduce soil bulk density in tillage cultivated layer, alleviate the viscous and acidification in red soil through improving soil total porosity and pH, and increase the soil nutrient and microbial biomass carbon and nitrogen contents, improve soil physical, chemical and biological properties, and finally increase rice yield. In a word, the addition of 30 t/hm² of woody peat had the most obvious effect on the construction of high-quality tillage layers of new cropland in red soil.

Abstract:In order to explore the ecological restoration significance of bryophytes in rocky desertification areas, four common bryophytes(Eurohypnum leptothallum, Brachythecium perminusculum, Bryum dichotomum and Cyrto-hypnum pygmaeum)in rocky desertification areas were selected. The biomass, saturated water absorption, root density, transpiration rate, and anti-scour ability were measured. For the first time, these four bryophytes were applied to the practice of rocky desertification restoration, and their soil enzyme activities were tracked and monitored for one year. The results showed that the water holding capacity of the four bryophytes was significantly different.(1)The biomass of the four bryophytes was ranked as follows:E. leptothallum > B. dichotomum > B. perminusculum > C. pygmaeum. The lowest saturated water absorption was C. pygmaeum (660.78±3.46)%, and the highest was E. leptothallum(1 627.82±4.68)%. (2)Bryum dichotomum showed that highest transpiration rate (6.63 g/(kg·h)) and was more easily to lose moisture, while E. leptothallum's moisture was less likely to lose than other bryophytes as it showed the lowest transpiration rate(0.93 g/(kg·h)). (3)There was a significant positive correlation between anti-erosion ability and root length density, root weight density and biomass. Eurohypnum leptothallum showed strong erosion resistance in each set of scouring experiments and could effectively reduce soil loss.(4)All four bryophytes could effectively increase the enzyme activity of the cultured soil. The bryophyte biomass, anti-erosion enhancement, and pseudo root density were positively correlated with soil dehydrogenase and urease activity. All four kinds of bryophytes had high water and soil conservation benefits, and the benefit of E. leptothallumwas more pronounced. It is recommended to use bryophyte in rocky desertification repair practices by using species succession rules.

Abstract:In order to reveal the effects of biochar addition on soil dissolved organic matter (DOM) and its dynamics in dryland,a located experiment was conducted to investigate the change characteristics of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC) and fluorescence spectra components of DOM and its UV spectra characteristics in different soils with different biochar additions during 2012 to 2017.The results showed that the application of biochar increased DOC and DIC contents in soil as a whole, and the contents increased with the increasing of the biochar addition amount. In the same amount of biochar treatment, the DOC content decreased significantly with the increasing of application time, while the DIC content increased gradually. The degree of DOM aromatization increase dsignificantly with the extension of application time. After three years of application, the aromatization degree of 3% and 5% addition amount treatments was both significantly lower than that of CK, but there was no significant difference between 1% addition amount treatment and CK.The molecular weight of DOM showed an increasing trend in different application years. With the increasing of the biochar amount, the difference in the molecular weight between different application years gradually decreased. The soil DOM mainly includes four kinds of substances:UVC humic-like (C1), UVA humic-like (C2), Soil fulvic acid (C3) and Tryptophan-like (C4), of which the C1 and C2 components dominated. In general, except for the addition of 1% biochar, the C2 component decreased with the increasing of the application years, the C1 and C2 components in different treatments gradually increased with the increasing of the application years, while the C3 and C4 components decreased significantly. The fluorescence indices of soil revealed that DOM was mainly terrestrially derived rather than microbial derived.The addition of biochar enhanced the bioavailability of DOM to some extent.The long-term application of biochar could result in changes of DOM components in the dryland. The general trend was that macromolecular humic-like substances increased, while small molecular proteins-like substances decreased.

Abstract:A branch gully of Liudaogou watershed in the wind-water erosion crisscross region of the northern Loess Plateau was selected as the object, and the effects of slope aspects and plant community types on soil organic carbon (SOC), total nitrogen (TN) content, ratio of carbon-nitrogen (C/N) and soil organic carbon and nitrogen density (SOCD, TND) were studied through vegetation survey and sampling analysis. The results showed that:(1) Slope aspects had significant effects on the SOC and TN contents in 0-20 cm, and C/N in 0-60 cm. The SOC, TN contents and C/N followed the order of semi-shady slope > semi-sunny slope > gully-head, semi-shady slope > semi-sunny slope=gully-head, and semi-sunny slope > semi-shady slope ≥ gully-head, respectively. (2) Plant communities had significant effects on the SOC and TN contents in 0-10 cm and C/N in 0-20 cm. There was no significant difference in SOC and TN contents between three kinds of leguminous communities growing in the semi-shady slope, namely, Lespedeza davurica, alfalfa and sweet clover, but they were significantly higher than that of the Stipa bungeana community. The SOC and TN contents in Lespedeza davurica and alfalfa communities were similar in the semi-sunny slope, which were significantly higher than those of the Artemisia capillaris and Stipa bungeana communities. The SOC and TN contents in Lespedeza davurica community were significantly higher than that of the Stipa bungeana community in the gully-head, indicating that legume herb was more conducive to the accumulation of soil carbon and nitrogen in the study area. (3) Slope aspects mainly affected the SOCD and TND in surface layer of 0-20 cm, and their contribution to SOCD and TND of 60 cm soil profile were 45%~55% and 47%~53%, respectively. There were significant differences in SOCD and TND between the surface layer and the whole soil profile under different plant community types. The average SOCD in the studied branch gully was estimated to be 2.13 kg/m², which was far lower than other parts of the Loess Plateau. These results had important role in evaluating soil carbon and nitrogen storage accurately and rational construction of vegetation in the crisscross area of wind-water erosion on the Loess Plateau.

Abstract:In 2017 and 2018, a field experiment with three regulated deficit irrigation amounts (non-deficit E1:100% of ET0, moderate deficit E2:80% of ET0, severe deficit E3:60% of ET0) and two wheat varieties (water-sensitive type X1:Xin Chun 22, water-insensitive type X2:Xin Chun 44) were conducted with drip irrigation for spring wheat in northern Xinjiang. The same nitrogen level of 300 kg/hm² and same irrigation frequency of one irrigation every 7 days were implemented. The soil moisture, nitrate nitrogen distribution and yield of spring wheat were studied. The results showed that:(1) These water deficit (E3) could alleviate soil water and nitrate nitrogen loss from 0-40 cm to the deep, it also reduced crop water consumption and improved water use efficiency. (2) There was no significant difference in soil mass moisture contents and soil nitrate nitrogen contents between Xin Chun 22 and Xin Chun 44, and wheat varieties had little influence on soil physical and chemical properties. (3) In moderate water deficit (E2), Xin Chun 44 (X2) saved a lot of water, and simultaneously, it improved water use efficiency and maintained the optimum nitrogen nutrition index (NNI).And consequently, the output was significantly compensated. But Xin Chun 22 (X1) could not be effectively compensated by moderate and severe water deficit. (4) With the same level of the nitrogen application and irrigation frequency, the wheat varieties had greater effects than the levels of regulated deficit irrigation on drip irrigation water use efficiency of spring wheat. (5)Taking into account NNI, water consumption, water utilization efficiency and yield, Xin Chun 44 (X2) was more suitable plant with regulated deficit irrigation model in northern Xinjiang, and its optimal regulated deficit irrigation treatment was E2.

Abstract:In order to explore the effects of different irrigation methods and irrigation amounts on the growth characteristics, physiological characteristics, yield, and irrigation water use efficiency of processing tomato under drip irrigation, the irrigation combination method suitable for processing tomato cultivation in arid regions of Xinjiang was sought to optimize the management of tomato planting in drip irrigation in arid areas. Pot test experiments were carried out on three irrigation methods(APRI,FPRI and CI)with three irrigation quotas(conventional irrigation level:1 060 mm,moderate water deficit:810 mm and severe water deficit:560 mm, the irrigation quota of APRI and FPRI are two thirds as CI) coupled with drip irrigation to explore plant height, stem diameter, leaf area index, photosynthesis, fluorescence, yield, irrigation water use efficiency and optimal irrigation combination model were studied. The results showed that the variation of plant height in different growth stages of processing tomato was:CW₁ > AW₁ > CW₂ > AW₂ > FW₁ > CW₃ > AW₃ > FW₂ > FW₃ (average), and the change of stem diameter and leaf area index was:AW₁ > AW₂ > CW₁ > CW₂ > AW₃ > FW₁ > CW₃ > FW₂ > FW₃ (average), growth potential and maximum growth rate of plant height, stem diameter and leaf area index were:AW₁ > CW₁ > CW₂ > AW₂ > FW₁ > CW₃ > AW₃ > FW₂ > FW₃; the interaction between irrigation method and irrigation amount had significant effects on P_n and T_r, in each growth period (P<0.01). Under the same irrigation mode, P_n and T_r increased with the increase of irrigation amount. The maximum is reached at AW₁. At W₁ level, P_n and T_r change to:APRI > CI > FPRI (average value). At W₂ and W₃ levels, P_n and T_r change to:CI > APRI > FPRI (average); The effect of irrigation method on F_v/F_m and F_v/F₀ of functional leaves of processing tomato was significant (P<0.01), and the effect on q^p was significant (P<0.05). The amount of irrigation on functional leaves of processing tomato on F_v/F_m and F_v/F₀ was not significant (P > 0.05), and the effect on q^p and NPQ in flowering and expansion period was extremely significant (P<0.01). The interaction between irrigation method and irrigation amount had a significant effect on the fluorescence parameters of processing tomato in each growth period (P<0.01). Among them, the maximum yield (Y) appeared in AW₁ treatment, which was 149 155 kg/hm²; the minimum appeared in FW₃ treatment, which was 57 060 kg/hm², a relative increase of 2.61 times. The research suggests that the full irrigation condition of alternate root-zoon irrigation can be used as a suitable irrigation combination model in this area. This study can provide a scientific basis for efficient water-saving production of processing tomato in drip irrigation in Xinjiang.

Abstract:In order to provide theoretical basis for the reasonable planting and water management of walnut production, this study analyzed the water consumption and photosynthetic characteristics of transpiration of walnut response to rainfall change. Through the artificial rainfall simulation environment (-50%, -25%, CK, +25%, +50%), pot seedling weighing method and a Li-6400 portable photosynthesis system measuring method were adopted to study transpiration of water consumption and photosynthetic characteristics of Xiangling, Qingxiang, and Liaohe1 seedling under different rainfall conditions, and use the membership function method to analyze the indicators. Results showed that:(1) The water consumption and water consumption rate of Xiangling, Qingxiang and Liaohe1 seedlings showed significant difference under different rainfall conditions (P<0.05), and the difference of water consumption at night was also obvious. The seedlings of Liaohe1 showed the largest water consumption at night in each rainfall condition, small water consumption rate, and good water holding capacity. (2) Under different rainfall conditions, the change of net photosynthetic rate (P_n) of Qingxiang and Liaohe1 seedlings was mainly limited by stomatal factors. Under water scarcity and extreme humidity, the change of net photosynthetic rate(P_n) of Xiangling seedlings was mainly limited by non-stomatal factors. (3) The water use efficiency (WUE) of Liaohe1 seedlings was at a higher level; the WUE of Xiangling seedlings was low in the rainfall increased by 50%; the WUE of Qingxiang seedlings increased sharply in the rainfall reduced by 50%. (4) Combining with the ranking of subordinate function results, Xiangling seedling was suitable for the water conditions that are relatively moist, Qingxiang seedling could grow in the extreme environment lack of water, and Liaohe1 seedling was with high adaptability in different rainfall conditions.

Abstract:In order to analyze the relationship and difference of hydrological function of the stands structure in the loess hilly regions of southern Ningxia, the characteristics of understory herb biomass and biodiversity, canopy rainfall redistribution, forest understory evapotranspiration and soil moisture were studied in three typical forest stands (Armeniaca sibirica pure forest, Armenia sibirica-Caragana korshinskii mixed forest, Armeniaca sibirica-Hippophae rhamnoides mixed mixed forest)located in Pengyang County during the growing season in 2017. The results were as follows:(1) The order of stands surface coverage was A.sibirica-H.rhamnoides (0.81) > A.sibirica-C.korshinskii (0.71) > A.sibirica (0.67), the aboveground biomass of herbaceous plants followed the order of A.sibirica- H.rhamnoides (0.86 t/hm²) > A. sibirica(0.62 t/hm²) > A. sibirica-C. korshinskii(0.41 t/hm²), and the herbaceous plant biodiversity was followed the order of A.sibirica-C.korshinskii > A.sibirica-H.rhamnoides > A.sibirica. (2) The canopies of the three stands were relatively sparse, and the rainfall penetration rate were all greater than 90%,and the penetration rainfall was linearly correlated with the rainfall outside the forest,the stemflow and the canopy interception were logarithmic related to the rainfall outside the forest. (3) The seasonal variation of forest understory evaoptranspiration was "single-peak type", and the size of forest understory evapotranspiration during the research period was followed the order of A.sibirica-H.rhamnoides (245.0 mm) > A.sibirica (227.7 mm) > A.sibirica-C.korshinskii (220.9 mm), among them, the intermonthly variation of A.sibirica-C.korshinskiiwas the minimum. (4) The soil moisture in the middle and upper layers (0-80 cm) basically showed decreasing trend during the growing season, while the deep soil moisture showed the opposite trend, and the difference in the deep soil moisture was showed as A.sibirica > A.sibirica-H.rhamnoides > A.sibirica-C.korshinskii.In the severe erosion and drought-stricken loess region, when restoring stable vegetation with water and soil conservation as the main function, it was necessary to consider the effects of vegetation allocation patterns on surface cover and herb biomass and species diversity, as well as to consider the effect on soil moisture.Therefore, it is recommended to choose A.sibirica-H.rhamnoides mixed forest and A.sibiricapure forest in the vegetation restoration.

Abstract:Using the field test method, through measuring annual growth and soil water content of dwarf Fuji(self-rooted anvil M_9-T337) in the field of Northern Shaanxi, long-term sequence meteorological data was collected and the potential evapotranspiration (ETc) of young mountain apple trees was calculated according to the Penman formula, and the result was compared with the annual rainfall of the year, then the water requirement of the second year saplings in the experimental area was obtained. The results showed that under the rainfall conditions in 2017, the sum of rainfall in the experimental area was greater than the sum of the water requirement of the saplings, but there was a stage of water shortage before July; further analysis showed that, no matter under the conditions of wet year, general year, general drought year or special drought year, due to the uneven distribution of rainfall time in Northern Shaanxi, although the annual rainfall was enough to meet the water demand for growth of fruit tree, there wasa serious water deficit before July. There even was water deficit before October in the special dry years. Four to five times of supplementary irrigations were needed to carry out before the germination of the fruit trees (March), the long-term growth of the branches (April), the flower bud differentiation period (May and June)and the flowering period (July), and the irrigation quota was determined according to the previous rainfall and the current soil water content. The irrigation amount range was 60%~80% of the orchard field water holding capacity.

Abstract:A barrels planted experiment was conducted to study the effects of PASP-Ca with different concentration levels on the dynamic changes of NH₄⁺, NO₃^- and total nitrogen (TN) concentrations in surface water of paddy field. The result showed that the concentrations of TN, NH₄⁺ and NO₃^- in the surface water of paddy field reached the maximum within 1 day, 3 days and 9 days respectively after nitrogen application. NO₃^-/TN was less than 0.1 and (NH₄⁺+NO₃^-)/TN was more than 0.5. Therefore, NH₄⁺ and TN could be used as the main monitoring indicators, and NO₃^- as an auxiliary indicator for the prevention and control of farmland water pollution. Adding a certain concentration of PASP-Ca had slow release effects for the changes of nitrogen concentrations in surface water of paddy field, while the effects of PASP-Ca at 0.3% concentration level was relatively better, the reduction rates of NH₄⁺ and TN in surface water of paddy field were 3.452 mg/(L·d) and 4.806 mg/(L·d) respectively. Compared with apply nitrogen only (CK), the reduction rates by 11.68% and 16.25%. Meanwhile, the average concentration of NH₄⁺ was 6.999 mg/L, which was 3.88% lower compared with CK. The average concentration of NO₃^- was 0.396 mg/L, which was 24.83% lower compared with CK. The average concentration of TN was 20.077 mg/L, which was 3.10% higher compared with CK. The dynamic changing trends of NH₄⁺ and TN concentrations with time could be expressed by logarithmic equations. After nitrogen application, the TN concentrations in paddy field decreased logarithmically with time, while the concentrations of NH₄⁺ increased logarithmically in 3 days, and then decreased logarithmically with time. 9 days after nitrogen application was the key stage to prevent nitrogen loss in surface water of paddy field.

Abstract:A field experiment was carried out to study the effects of different mixed ratios of controlled-release urea (CRU) and conventional urea (CU) on soil nitrogen content, its uptake and utilization of maize (Zea mays L.) and grain yield. All treatments were applied with the same rate of nitrogen. The results showed that nitrogen fertilization significantly increased soil available nitrogen and total nitrogen contents in tillage layers of 0-20 cm and 20-40 cm. When using conventional urea, single basal application increased soil nitrogen content in the early growth stage, while twice application could improve the nitrogen content in the late growth stage. Compared with the conventional urea application, the single basal application of urea with a certain proportion of controlled-release urea significantly improved soil nitrogen content in tillage layer in each growth period. The suitable proportion of controlled-release urea mixed with conventional urea increased the nitrogen accumulation in maize in the middle and later stages to some extent, improved the apparent utilization rate of nitrogen fertilizer, the efficiency of nitrogen fertilizer, fertilizer contribution and the key enzymes activities of nitrogen metabolism in function leaves. At the same nitrogen application rate, the effect of the single basal application of the mixed fertilizers was even better than the twice applications of conventional urea. With the increasing proportions of controlled-release urea, the maize yield first increased and then decreased, and the yield under the treatment of 75% controlled-release urea+25% conventional urea was the highest, which was 12.09% (2014) and 21.58% (2015) higher than single basal application of conventional urea fertilizer, 8.27% (2014) and 14.19% (2015) higher than the twice fertilizations, respectively. Therefore, the conventional urea mixed with 75% controlled-release urea could not only harmonize the soil nitrogen supply throughout the maize growing period, but also reduce the times of fertilization, and consequently cut the labor input.

Abstract:In order to solve the problems during dryland maize production in cold climate areas, such as drought and water shortage, low temperature, soil fertility decline and so on, a field experiment was conducted with split plot design in the demonstration base of dryland water-saving agriculture in He village of Yangqu county, Shanxi Province in 2011-2016. The effects of conservation tillage on soil environment and yield of dryland maize were studied with six different tillage mulching treatments. The results showed that:(1) Compared with conventional rotary tillage and plastic film mulching (CTP), no-tillage, straw and plastic film mulching (NTSP) and strip-tillage, straw and plastic film mulching (STSP) increased soil water storage by 20.8 mm and 32.1 mm respectively in 0-200 cm. Compared with conventional rotary tillage and bare land (CTO), no-tillage, semi straw mulching (NTSS) and strip-tillage, semi straw mulching (STSS) increased soil water storage by 24.3 mm and 16.3 mm respectively in 0-200 cm. (2) The difference of soil densities among different treatments mainly occurred within 15 cm, with 2.6 times under strip-tillage as much as the conventional rotary tillage. In the first year of no tillage, soil density was the highest, 4.6 times of that conventional tillage, and then decreased year after year. (3) Compared with CTP, the daily average soil temperature under NTSP and STSP decreased by 0.2℃ and 0.1℃ (5 cm), 0.8℃ and 0.3℃ (10 cm). Compared with CTO, the daily average soil temperature under NTSS and STSS decreased 0.7℃ and 0.4℃ (5 cm), 1.5℃ and 1.0℃(10 cm). (4) After 3 years of conservation tillage, no tillage and strip-tillage increased soil organic matter contents in 0-20 cm by 1.5 g/kg (film mulching) and 1.2 g/kg (no film mulching) averagely compared with conventional rotary tillage. And after 5 years, the effect of fertilizing soil was more obvious. (5) The economic yields under NTSP and STSP increased by 4.4% and 6.9%, respectively, compared with CTP, and the economic yield of STSP was significantly higher than that of CTP. There was no significant difference in average yield between NTSS, STSS and CTO. Generally, STSP is the appropriate conservation tillage for the area to store water and preserve soil moisture, to fertilize the soil, and to maintain stable and high yield.

Abstract:Soil desertification is one of the most serious environmental problems in the world.Soil fertilization and vegetation restoration are the key links in desertification governance. As a agricultural waste, crop straw still retains rich organic matter and nitrogen, phosphorus and potassium nutrients, and is a natural organic amendment. Granulation of straw can significantly improve straw returning and improve soil fertility.Using agricultural waste (straw) as the main raw material, adding polyacrylamide, microbial agents and NPK fertilizers, and processing them into granulated straw amendment (GSA).In order to investigate the effects of GSA on soil fertilization and vegetation growth in the alpine sandy land of Northwest Sichuan, a field experiment with blank control (CK0), local conventional yak dung treatment (CK1) and four application levels of GSA (6, 12, 18, and 24 t/hm²)were conducted.The results showed that compared with CK0, both GSA and CK1 significantly increased soil total nitrogen, total nitrogen density, total nitrogen storage and nitrate nitrogen content. GSA and CK1 also increased the plant height, total root length, total root surface, average root diameter, root volume and dry weight of single plant (DWSP) of ryegrass(p<0.05). The application of GSA and CK1 increased the soil nitrogen content and promoted the growth of ryegrass.The effect of GSA on the nitrogen content of sandy soil and the growth of ryegrass was better than that of CK1. Compared with CK1, the average of total nitrogen content, total nitrogen density, total nitrogen storage and nitrate nitrogen content increased respectively by 12.50%, 22.73%, 20.90% and 344.56% under the treatment of GSA.The average of shoot and root DWSP of ryegrass also increased respectively by 57.50% and 66.86%, when compared to CK1. Increasing the application rate of GSA can effectively increase soil nitrogen contentand the growth indexes of ryegrass also increases gradually.When the application rate exceeds 18 t/hm², the total nitrogen content, total nitrogen density and total nitrogen storage in the 0-10 cm layer, and the growth indexes of ryegrass are not significantly different.There was a significant correlation between soil nitrogen and DWSP of ryegrass, and the correlation between soil total nitrogen and total nitrogen and DWSP of ryegrass was the highest (r ≥ 0.90^**).The leaching rate of exogenous nutrients decreased at first and then increased with increasing the application rate of GSA, with a minimum at 18 t/hm². Considering the changes of soil nitrogen content, exogenous nutrient leaching rate and growth of ryegrass, the optimum application rate of GSA in sandy soil of northwest Sichuan is 18 t/hm².

Abstract:Excessive application of fertilizers is one of the major problems that hinder the sustainable development of dryland agriculture. Summer maize was taken as the object in the paper, and the rain-proof barrel experiment was conducted to accurately control the water and fertilizer supply, then the effects of super aborbent polymer(SAP) and five kinds ratio of nitrogen and phosphorus fertilizers (1:4, 2:3, 1:1, 3:2, 4:1) on soil fertility, plant growth, nutrient uptake and utilization of maize were studied. The results showed that the balanced application of SAP with N and P could promote plant growth and the absorption and utilization of nutrients. The average plant height and the leaf area increased by 3.36%~7.19% and 5.36%~29.26%, respectively. Compared with other treatments, the dry matter accumulation and nitrogen and phosphorus accumulation increased by 13.79%~27.61%, 15.91%~32.47%, 18.66%~33.75%, respectively. Compared with no SAP treatment, the soil inorganic nitrogen content decreased by 5.42%, and the available phosphorus content increased by 3.55%.Under the conditions of this experiment, the maximum yield of 113.93 g/pot was obtained by applying SAP 1.68 g/pot, N 2.89 g/pot, P 2.89 g/pot, and the yield at harvest increased by 18.69%~30.94%.The results provide a reference for the application of nitrogen and phosphorus fertilizers for summer maize under the condition of applying SAP in North China.

Abstract:Albic soil with continuous rotary tillage has resulted in some problems, including shallow plough layer, sticky and tight subsoil and unbalanced nutrient distribution. In order to explore suitable tillage and fertilization modes in paddy fields to improve albic soil productivity and rice yield in Jianghuai region, a field experiment was carried out to study the effects of different tillage and fertilization practices on physicochemical properties, the distribution of water-stable aggregates and rice yields in albic soil. The treatments consisted of two tillage practices (rotary tillage and conventional tillage) and three fertilization modes (chemical fertilizer, chemical fertilizer+organic manure, chemical fertilizer+straw returning). The results showed that compared to rotary tillage, conventional tillage reduced the soil nutrient contents of 0-10 cm soil layer, but increased the contents of organic matter, total nitrogen, available phosphorus and available potassium in 10-20 cm soil layer by 3.2%~8.8%, 4.5%~9.2%, 5.2%~8.2% and 8.3%~17.7%, respectively. The amendment of organic manure or straw returning increased the contents of soil organic matter and available potassium by 1.3%~8.6% and 4.1%~21.1%, respectively. The bulk density in 10-20 cm soil layer under conventional tillage was 14.4%~19.5% lower than that of rotary tillage, and the percentages of soil macro aggregates under conventional tillage were lower than rotary tillage by 3.0%~5.4% in 0-10 cm soil layer and 3.5%~9.7% in 10-20 cm soil layer, respectively. Under conventional tillage, the amendment of organic manure or straw returning reduced soil bulk density by 2.1%~6.6% and increased the percentage of macro aggregate by 2.8%~8.4%, compared to chemical fertilizer application. The rice yield under conventional tillage was 11.7%~18.0% higher than rotary tillage, and the amendment of organic manure or straw returning enhanced the rice yield by 1.7%~7.5%. Therefore, in albic soil with continuous rotary tillage in Jianghuai region, conventional tillage combined with straw returning or organic manure amendment was beneficial to improve soil physical and chemical properties of the 0-20 cm soil layer and increase rice yield.

Abstract:To understand the effect of long-term rice cultivation on the particle composition of surface soil layer in paddy field of the southern China, the difference in clay content between tillage layer (including plow layer) and subsurface of paddy soils was studied using historical data, the influence of rice cultivation time on the particle composition of different soil layers in the paddy soils was investigated in three typical areas, the difference in particle composition between field drainage sediments and corresponding paddy soils was compared in 21 fixed-point observation fields. The effect of long-term rice plantation on the texture differentiation of the paddy soil profiles was discussed. All investigations were carried out in Zhejiang province. Statistical results of 456 representative paddy soil profiles in Zhejiang province showed that, the clay content in plough and plow layers decreased by 14% and 10%, respectively, as compared with their subsurface soils. Comparison investigation from three types of paddy soils developed from coastal sediment (from 10~20 years to>80 years), quaternary red clay (from 5~20 years to >70 years), and basalt (from 5~20 years to 35~70 years), respectively, showed that contents of sand in the plough and plow layers in the soils increased with increasing rice plantation time, while that of clay decreased with increasing rice plantation time. The ratio of the clay content of the plough and plow layers to their subsurface decreased gradually with the increase of the rice plantation time. The contents of clay and silt in the sediments from farmland drainage were higher than those in the corresponding farmland soils, while the sand content was lower than that in the corresponding soils. It was considered that long-term rice cultivation could result in soil sanding with increase of sand and decrease of clay. That was due to both the selective loss of clay and silt particles in the drainage and mechanical eluviations of clay particles during anthropogenic tillage.

Abstract:To investigate the effect of reduced fertilization on rice yield and soil fertility, the rice yield, soil organic matter, available NPK and effective copper, zinc, iron and manganese content after 10 years of reduced fertilization and straw returning in the Chaohu Lake Basin were tested. Soil enzyme activity was measured and analyzed. The results showed that long-term nitrogen reduction of 30% or 50% phosphorus reduction had no significant effect on rice yield, but reduction + straw yield had an effect on yield increase, but the yield was not significant; reducing nitrogen by 30% or reducing phosphorus by 50% would reduce soil The content of organic matter increased the content of available potassium and alkali-hydrolyzed nitrogen in the soil. The content of available phosphorus in soil reduced significantly by 50% of phosphorus reduction, and the amount of available organic matter, available potassium, alkali-hydrolyzed nitrogen, and effective copper and zinc were increased by reducing the amount of straw + returned to soil. The iron and manganese content had no significant effect on the increase of available phosphorus. Compared with no fertilizer application, fertilization could significantly increase soil enzyme activity. Decreasing N and P fertilizers would reduce enzyme activity in the soil to a certain extent. The reduction + straw returning to urease The effect of the increase was not obvious, but it would significantly increase the activity of neutral phosphatase and sucrase in soil. There was a significant or highly significant positive correlation between soil enzyme activity and rice yield and soil nutrient content. Considering the effect of reduced fertilization on rice yield and soil fertility, we can put forward the implementation of reducing fertilization and straw returning in Chaohu Lake Basin instead of optimizing fertilization.

Abstract:To explicit proper nitrogen fertilizer application of machine-transplanted double rice, a two-year (2013-2014) field experiment was conducted to study the effects of amount, ratio and period of nitrogen fertilizer application on the yield and nitrogen use efficiency of machine-transplanted double rice in double-cropping rice areas of the middle reaches of the Yangtze River (Shanggao of Jiangxi). The main results were as follows. Moderate amount of nitrogen fertilizer could increase effective panicle number and grain number per panicle, thereby increased spikelet number. For machine-transplanted double rice, the optimal nitrogen fertilizer application amount was 180 kg/hm² for the early rice and 195 kg/hm² for the late rice, which could maintain higher yield and utilization and absorption rate of nitrogen. Under the proper nitrogen application rate, ratio and period of nitrogen application had significant influences on yield and nitrogen utilization and absorption. The optimal ratio of basal tiller fertilizer and panicle fertilizer was 8:2 to 7:3 for the early rice, and 7:3 for the late rice. Appropriate time for top nitrogen application was 7 days after transplanting and the stage of the second leaf to top shooting out. The optimal ratio and time of nitrogen application was beneficial to maintain higher leaf area index (LAI) and dry matter accumulation, coordinated ratio of grain and leaf, sufficient panicle number, larger panicle type and high total spikelet quantity, while maintain high utilization and absorption rate of nitrogen.

Abstract:Spatial variability of stoichiometric characteristics of soil carbon, nitrogen and phosphorus and its influence factors were systematically analyzed through classical statistics analysis and geostatistics analysis methods in Rapeseed Planting areas of Jiangxi Province. The results showed that the averaged values of soil organic carbon (SOC), total nitrogen (TN) and total phosphorus(TP) contents were 16.99 g/kg, 1.44 g/kg and 0.50 g/kg respectively, and soil C:N, C:P, and N:P were 12.28, 38.31 and 3.27 respectively. The ecological stoichiometric ratios were 33.86:2.88:1, and the ratios were at a relatively low level, indicating that there existed variation coefficients and spatial variability with a moderate degree, which also suggested the spatial variability of soil C:N, C:P and N:P were determined by the co-effects of structural and random factors in Jiangxi Province, and the structural factors played a more important role. From the characteristics of spatial distribution, SOC, TN, and TP content trend to be high in northeast and low in southwest. The high-value region of soil C:N mainly distributed in the north of Jiangxi Province and the distribution area was small, while the low-value region was mainly distributed in West Jiangxi, Northwest Jiangxi, Southwest Jiangxi and East Jiangxi. Soil C:P and N:P had the same spatial distribution characteristics as well, the high-value region was located on Southwest Jiangxi and Northeastern Jiangxi sporadically; The low-value region was mainly distributed in Northwest Jiangxi and South Jiangxi. Regression analysis showed that soil parent materials, soil types, topography, climate condition and cropping system had very significant impacts on soil C:N, C:P and N:P ratios (P<0.01). The soil parent materials were able to explain 16.6%, 3.7% and 7.0% of soil C:N, C:P and N:P spatial variability, respectively. The topography factors could explain 3.5%, 2.9% and 4.2% of the spatial variability, respectively. The explanatory power of cropping system were 9.7%, 4.4%, and 7.6%. The annual fertilizer Nitrogen application explained 3.9%, 4.4% and 7.6% of soil C:N, C:P and N:P spatial variability, respectively. However, The explanatory power of soil types and climate condition were 16.8%, 5.1%, 9.0% and 13.4%, 9.8%, 15.2%, respectively, which suggested that soil types and climate condition were the dominant factors in controlling the spatial variability of soil C:N, C:P and N:P.

Abstract:In order to explore the effect of straw biochar on vertical migration of inorganic nitrogen and phosphorus in surface layer of black soil during freezing-thawing period.This research adopts the indoor simulation of freezing-thawing cycle experiment, set the freezing-thawing and not-freezing-thawing, freezing-thawing cycles, biochar apply three influence factors, to analyze the vertical migration characteristics of soil surface inorganic nitrogen and phosphorus under freezing-thawing with different straw biochar apply. (1) Results show black soil surface freezing-thawing and not-freezing-thawing, freezing-thawing cycles and biochar apply have significant effect on NO₃^--N, NH₄⁺-N and PO₄^3--P inorganic nitrogen and phosphorus migration liquid total volume, total concentration and total amount of migration through freezing-thawing and not-freezing-thawing, freezing-thawing cycles and biochar apply.(2) The leaching time was shortened with the increase of freeze-thaw action and prolonged with the increase of biochar application.All treatments of inorganic nitrogen and phosphorus migration liquid volume show a decrease trend with the increase of biochar input. The total volume of migration liquid in not-freezing-thawing group show a slowly decrease trend as the incubation period increase. The total volume of the migration liquid volume in the freezing-thawing group increases sharply in the 5th freezing-thawing cycle test, and then became stable. (3) The effect of biochar on the vertical migration and accumulation of inorganic nitrogen and phosphorus under freeze-thaw action was analyzed. During the same control period, the inhibition of biochar on the vertical migration of inorganic nitrogen and phosphorus in the freeze-thaw group was greater than that in the non-freeze-thaw group.Because of changes in the physical properties of the soil,the accumulated migration of the freezing-thawing group NO₃^--N,NH₄⁺-N and PO₄^3--P changed dramatically around the fifth freezing-thawing cycle.To sum up, biochar can effectively retain nutrients during freezing-thawing period, and the research results can provide some theoretical support for the prevention and control of rural surface pollution during thawing period in cold regions.

Abstract:To investigate the effect of colloid on uranium (VI) transport in saturated porous media in the presence of soluble organic matter, two kinds of quartz sands (fine sand and coarse sand) were selected, and the column experiment with homogeneous configuration was constructed to study the effect of kaolinite colloid on the U(VI) migration in two quartz sands with different particle size in the presence of humic acid under saturated water flow. The results showed that the breakthrough curves of tracer in two homogeneous columns were similar and symmetric. When the U(VI) solution only was introduced into the column, the mobility of U(VI) in the two columns was small (<25%), and a large amount of U(VI) were adsorbed on the quartz sand through surface complexation. When humic acid and kaolinite colloids were present in the U(VI) solution, the transport amounts of U(VI) in both two columns were increased, and the transport amount (58.36%) in the quartz sand with 600~850 μm was more than that (42.68%) in the quartz sand with 250~425 μm. This demonstrated that humic acid-kaolinite colloids and sand size had large influence on uranium migration in subsurface environment.

Abstract:The effect of C/N ratio on nitrogen and COD removal in combining surface flow and horizontal flow constructed wetlands under different influent nitrogen concentrations, as well as the preliminary influence mechanism was investigated in this simulation experiment. The results showed that, during the vegetative period and the flowering period, low C/N ratios were in favor of total nitrogen and ammonium-nitrogen removal in the wetlands, and nitrate-nitrogen removal was more complete with C/N ratio increasing, while nitrification in the wetlands limited nitrate-nitrogen removal under low C/N ratio. Comparing the two growth periods, the removal capacity of total nitrogen as well as nitrate-nitrogen was similar under different C/N ratios, whereas ammonium-nitrogen removal was higher during the vegetative period than during the flowering period. However, no obvious influence on COD removal by C/N ratio was found in all the treatments at the same growth period, and COD removal was also similar during the two growth periods, and their efficiencies in all the treatments were greater than 90%. With the increase of retention time, the removal efficiencies of both nitrogen and COD increased. The effluent pH value generally rose firstly and then kept a stable trend in all the treatments, while oxidation-reduction potential dropped firstly, rose secondly and then maintained a stable trend. The pH value decreased with C/N ratio increasing in the effluent, while oxidation-reduction potential increased. Besides, pH value was higher during the vegetative period than during the flowering period in the effluent, while oxidation-reduction potential was lower during the vegetative period than during the flowering period. Influent C/N ratio and the wetland system jointly affected the effluent pH and oxidation-reduction potential.

Abstract:In this study, the extracting experiment was conducted to investigate the effect of EDTA and citric acid (pH=4) on P mobilizationin in the grain field soil, greenhouse soil and P-stabilized greenhouse soils under different concentrations (0, 0.05, 0.1, 0.25, 0.5, 1.0 g/L) and different extraction times (1, 12, 24, 48, 72 h), to make sure the optimal concentration and extraction time of chelating agent to extracts P from soils. The results indicated that the optimal concentration and extraction time were 0.05 g/L and 12 h for EDTA and citric acid in grain field soil. The optimal concentration and extraction time were 0.5 g/L and 12 h for EDTA and citric acid in green house soil, alum-stabilized soil and mixed-stabilized (alum:dolomite was 1:1) soil. The optimal concentration and extraction time were 0.5 g/L and 1 h for EDTA and citric acid in dolomite-stabilized soil. Generally, the effect of citric acid was better than that of EDTA, especially in alum and dolomite stabilized soil.

Abstract:A nylon net bag embedding method was carried out to study the decomposition and nutrient release of green manure Viciavillosa and ryegrass in coastal saline soil with different salinity. The results showed that the dry matter residue rate, total organic carbon content and C/N ratio of ryegrass in different salt plots were higher than those of V. villosa. The nitrogen and potassium of V. villosa were released rapidly in the first 15 days, and the residual rates in different salinity plots were 20.4%~34.0% and 13.2%~18.1% respectively. The potassium of ryegrass was released by nearly 90% in the initial 45 days, and the releasing of nitrogen and phosphorus continued in the whole decomposition process.The final residual rate of sodium in green manure in low salinity plots was 5.2%~7.6%, and in high salinity plots was 36.2%~49.2%.The residual rates of magnesium, calcium and zinc in ryegrass in different salinity plots were higher than those in V. villosa. The release of copper was mainly in the initial 45 days, and then tended to stagnate. The nutrient enrichment of magnesium, iron and manganese appeared in decomposed 45 to 60 or 45 to 75 days respectively. In general, the residue rate of dry matter and nutrient in gramineous green manure was higher than that of leguminous green manure. High salinity obviously blocked the release of nitrogen, calcium, magnesium, iron, manganese, copper, zinc and other nutrients in green manure.

Abstract:In order to study the effect of the basic physicochemical properties on microbial diversity, three different flooded paddy in the Southwestern China were selected. Drying method, potential metric method, static indoor culture method, diluted coating plate method and chloroform fumigation method were used to test the soil physicochemical and biological indexes. The results indicated that:(1) The water content of each sample area gradually reduces along the vertical depth. The pH value was between 6.3~7.1 from slightly acidic to neutral. Ammonium nitrogen (NH₄⁺-N) content ranged as Hechuan flooded paddy field>Shapingba flooded paddy field>Beibei purple soil base, and the surface (0-10 cm)>subsurface stratum (10-20 cm)>bottom (20-40 cm), while the overall content was 36.97~52.02 mg/kg. The difference of nitrate nitrogen (NO₃^--N) in three kinds of flooded paddy fields was not significant (2.13~2.61 mg/kg). (2) The content of microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) in Beibei purple soil base was the most, followed by Hechuan flooded paddy field, and Shapingba flooded paddy field, while the content of MBC and MBN decreased with the increase of soil depth. (3) The microbial abundance showed the trend of bacteria>actinomycetes>fungi, and decreased with the increase of soil depth. The Pearson relationship analysis showed that the abundance of soil bacteria, actinomycetes and fungi had a significant negative relationship with each other (p<0.01). The microbial abundance showed the trend as Hechuan flooded paddy field>Shapingba flooded paddy field>Beibei purple soil base.

Abstract:To investigate the effects of coal gangue on revegetation and microbial properties of an alkali-saline soil, coal gangues with different application rates (0, 10%, 20%, 30%, 40%, 50%) and different particle sizes (small-size of <1 mm, medium-size of 1~5 mm, large-size of >5 mm, mixed-size) were applied to an alkali-saline soil. Then the alfalfa pot experiment was conducted to determine the height and biomass of alfalfa and soil microbial biomass and enzymes activities. The results showed that soil microbial biomass C and N, activities of urease, catalase and dehydrogenase, as well as plant height and biomass of alfalfa all increased first and then decreased with the increase of coal gangue application rates. As for the mixed-size, small-size, medium-size, and large-size coal gangue treatments, the above soil properties reached their peaks when the application rates were 20%, 20%, 30%, and 40%, respectively. Among them, coal gangue application rate of 20% with mixed partical size gave the best improvement effect on revegetation of alkali-saline soil. The plant height and fresh weight of alfalfa significantly were increased by 34.86% and 45.28%, respectively. Therefore, the application of coal gangue could improve the ecological quality of saline-alkali soil. The coal gangue with mixed particle size and 20% application rate could be used as an effective amendment for the revegetation of alkali-saline soil.

Abstract:The gramineous Lolium perenne L. and leguminous Vicia villosa Roth had been intercropped in apple orchard for 6 years. The organic carbon fractions in different depth of soil and the daily variation of the respiration rate in surface soil were investigated in the orchard. The results showed that the L. perenne and V. villosa intercropped significantly increased the content of total organic carbon (TOC) and the content of organic carbon components, such as light organic carbon (LFOC), dissolved organic carbon (DOC), particulate organic carbon (POC), readily oxidation of organic carbon (ROC) and microbial biomass carbon (MBC), in 0-20 cm and 20-40 cm soil layer in apple orchard, and the increase degree caused by V. villosa both was higher than that by L. perenne. In 40-60 cm soil layer, only soil DOC content was increased by intercropping. The content of all organic carbon fractions in 0-20 cm layer soil and TOC, DOC, POC and ROC in 20-40 cm layer soil in the orchard intercropped V. villosa were significantly higher than that in the orchard intercropped L. perenne. There were positive relationships between TOC and LFOC, TOC and POC, DOC and LFOC, DOC and MBC, DOC and ROC, MBC and ROC, ROC and POC, and between LFOC and ROC. The rate of soil respiration had the positive relationships with LFOC, DOC, MBC, and ROC. The rate of soil respiration was increased significantly by intercropping L. perenneand and V. villosa; the characteristics of the peak type were more obvious under the intercropping condition during the day, while the effect of intercropping V. villosa was better than that of L. perenne.

Abstract:In order to study the effects of Cinnamomum camphora plantations on properties of degraded red soil and utilization of microbial carbon sources in eastern Hu'nan, forest soil and non-forest soil samples were paired sampled and analyzed. The results showed that the pH in forest soil was significantly increased by 0.95 units compared with non-forest soil, and the total phosphorus, total potassium and water contents were significantly increased by 14.8%, 16.8% and 45.6%, respectively. But the soil bulk density was significantly decreased by 8.1%. The average well color development (AWCD) of soil microorganisms was significantly increased by long-term Cinnamomum camphora restoration. Furthermore, the microbial metabolic intensities of carbohydrates, amino acids, carboxylic acids, polymers and phenolic compounds in non-forest soil were only 27.6%, 19.2%, 23.4%, 47.1% and 3.5% of those in forest soil, respectively. In addition, soil microbial functional diversity indexes were significantly increased by long-term Cinnamomum camphora restoration. Principal component analysis (PCA) showed that Cinnamomum camphora plantations changed the carbon sources utilization pattern of soil microbial community. Correlation analysis showed that the improved soil physical and chemical properties after Cinnamomum camphora restoration were reasons for the improvement of microbial carbon sources utilization capacity and functional diversity indexes, and among which, soil pH was the primary driving factor. In conclusion, Cinnamomum camphora plantations could improve the microbial ecological function of degraded red soil in eastern Hu'nan, and Cinnamomum camphora is a suitable tree species for ecological restoration and reconstruction of degraded red soil.

Abstract:In order to reveal the improvement effects of different Ulmus pumila strains on soil salt in coastal saline alkali land and the distribution and absorption characteristics of salt ions in the soil:Ulmus pumila system, and to select the salt tolerant Ulmus pumila strains for afforestation in coastal saline alkali soil, six species of Ulmus pumila (No.1, 5, 28, 30, 46, 105 respectively) with 4 years old under moderate saline habitat were taken as test materials. Through field sampling and lab analysis, the distribution characteristics of salt ions (Na⁺, K⁺, Ca²⁺, Mg²⁺) in roots, stems, leaves of Ulmus pumila and soils were analyzed. The results showed that:(1) Ulmus pumila could significantly reduce the total salt contents of coastal saline alkali land, and the salt contents under different Ulmus pumila strains were 55.0%~63.1% lower than that of the control, Ulmus pumila of No. 30 gave the biggest reduction. (2) All the Ulmus pumila accumulated Na⁺, K⁺, Ca²⁺ and Mg²⁺ preferentially in the leaves, and high K⁺/Na⁺, Ca²⁺/Na⁺ and Mg²⁺/Na⁺ ratios were maintained in leaves. Ulmus pumila could adapt to salt stress by establishing new ionic equilibrium. (3) The absorption selectivity coefficients for all different Ulmus pumila strains were S_K,Na > S_Ca,Na > S_Mg,Na. The absorption selectivity of K⁺ was greater than those of Ca²⁺ and Mg²⁺. Different Ulmus pumila strains had different absorption ability for Na⁺, K⁺, Ca²⁺ and Mg²⁺, among which No. 28 had the highest absorbency to K⁺, And No. 5 had the strongest absorbency to Ca²⁺ and Mg²⁺.

Abstract:A pot experiment was conducted to evaluate the effects of different biochars derived from coconut shell, bamboo sawdust, dead pig and tobacco stalk respectively (at 3% application rate) on the physicochemical properties of tobacco-planting soil, agronomic characteristics of tobacco plant and chemical composition of the flue-cured tobacco leaves. The results showed that the electrical conductivity, contents of available nutrients and organic carbon and enzyme activities of the tobacco-planting soil were influenced significantly by the application of different biochars. The highest content of soil organic carbon was observed in the bamboo biochar treatment, which increased by 146.37% compared to the control. Moreover, the application of pig biochar significantly (p<0.05) increased the electrical conductivity, available phosphorus and potassium, and promoted the activities of catalase and urease in tobacco-planting soil. The application of biochars had a slight influence on the agronomic traits of tobacco plant. The stem girth of tobacco plant in pig biochar treatment increased by 0.78 cm compared to the control. The biomass of tobacco plant significantly (p<0.05) increased, as the dry weight of tobacco leaves increased by 58.07% and 47.01% in the pig biochar and tobacco stalk biochar treatments, respectively, compared to the control. In addition, after the application of bamboo biochar, pig biochar and tobacco stalk biochar, the contents of nicotine, nitrogen, potassium and reducing sugar in flue-cured tobacco leaves all conformed to the standard of high quality tobacco. The application of pig biochar also significantly (p<0.05) increased the content of chloride in flue-cured tobacco leaves, and adjusted the sugar/nicotine and nitrogen/nicotine ratios to meet the standard of high quality tobacco. In conclusion, pig and tobacco stalk biochars were more effective than others in improving tobacco-planting soil properties and nutrient status, as well as promoting tobacco biomass and quality in the present study.

Abstract:To investigate the effect of arsenic on the growth of millet seedlings and the critical concentration of millet stress, the As concentrations were set to 0, 2, 4, 8, 10 mg/kg for quartz sand. Substrates, through cultivation and pot experiments, analyzed the effect mechanism of As on the germination, seedling growth and antioxidant enzyme system of millet. Studies have shown that:Low concentrations of As (<4 mg/kg) can promote millet germination, high concentrations of As (<4 mg/kg) inhibit millet germination, when the As concentration of 2 mg/kg, the millet germination potential, germination rate and germination index in all treatments the highest value. They were 18.67%, 32.00%, and 19.00%, respectively. The low concentration of As promoted the growth of millet seedlings, and the high concentration had an inhibitory effect. When the As concentration was 2 mg/kg, the plant height, root length, fresh shoot weight, and under ground fresh weight of millet were all reached. The maximum values were 15.46 cm, 7.34 cm, 0.64 g, and 0.16 g, respectively. As the concentration gradient of As increased, the fresh weight of the under ground layer increased first and then decreased, and the promotion and inhibition of the root system was greater than that of the shoot. The content of As in the roots of millet seedlings was significantly higher than in the shoots, and the TF value gradually dccreased. When As concentration was less than 4 mg/kg, As could promote the synthesis of chlorophyll in millet. When As concentration was 2 mg/kg, the total amount of chlorophyll a, chlorophyll b and chlorophyll in millet was significantly higher than that of the control 28.38%, 51.60% and 37.06%, when the concentration of As was higher than 4 mg/kg, the chlorophyll synthesis of Millet was inhibited; with the increase of As concentration gradient, the SOD activity of millet seedlings continued to increase, and the activities of POD and CAT increased first and then decreased, but higher than the contro. When the As concentration exceeded 8 mg/kg, the POD activity of the millet seedlings began to decrease. After the As concentration exceeded 4 mg/kg, the CAT activity began to decrease. After As concentration higher than 8 mg/kg, the POD actibvity of millet seedlings began to decrease. The results showed that low concentration of As (<4 mg/kg) promoted the germination and seedling growth of millet, and the high concentration of As(≥ 4 mg/kg) inhibited the germination and seedling growth of millet, and the root system was more sensitive to As stress, and the activity of antioxidant enzyme system (POD, CAT) was reduced. The research can provide a scientific basis for the anti-pollution cultivation and pollution-free production of millet.

Abstract:In order to utilization of biogas slurry, this paper used a 3-years fixed site field experiment to study the effects of pig manure biogas slurry application on soil physical and chemical properties, and to assess the potential pollution risk of heavy metals in the soil. The planting pattern of the field experiment was rice-rape rotation, fertilization treatments included 2 controls of water and chemical fertilizer, and 10 application rates of pig manure biogas slurry. The indexes of single factor pollution, Nemerow pollution comprehensive and Hakanson pollution index of potential ecological risk were selected as evaluation indexes of the soil heavy metal pollution and potential ecological risk.The results showed that after 3-year application of biogas slurry in a total amount of(546.25~626.00)×10³ kg/hm²,the soil fertility and structure were significantly improved. It is worth to note that nitrogen fertilizer should be properly applied to cropland, in order to prevent soil nutrient imbalance. The contents of Cd, As, Pb, Cr and Hg were increased in the biogas slurry treated soils with an increasing application of biogas slurry. Furthermore, Pb, Cd, Cr, and As show slightly potential ecological pollution risk, and Hg exhibited a medium risk of potential ecological pollution, indicating biogas slurry can be safely used in agricultural production. This study indicates that the long-term application of biogas slurry is beneficial for the soil ecological function and the production of food security. Nevertheless,proper management of soil Hg and As is required to prevent soil contamination.

Abstract:In order to find a sustainable improvement method for acid tobacco-planting soil, afield experiment was conducted to study the effects of lime, lime combined with green manure on the physical properties, nutrients and acidity indexes of acid tobacco-planting soil in flue-cured tobacco continuous cropping and flue-cured tobacco and corn rotation systems. The correlation between soil pH and soil physical and chemical indicators was analyzed. The results were as follows:Under the flue-cured tobacco continuous cropping pattern, combined application of lime with green manure reduced soil bulk density, hydrolyzed acid, exchangeable acid, exchangeable hydrogen and aluminum by 11.97%, 25.00%, 18.46%, 21.74% and 16.67% respectively, and increased soil porosity, organic matter, alkali-hydrolyzable N, available P, available K, pH, cation exchange capacity, base saturation, soil buffer capacity by 42.26%, 57.02%, 11.86%, 16.39%, 50.65%, 5.97%, 8.05%, 13.17% and 81.90% respectively compared to lime application alone. Under combined application, flue-cured tobacco and corn rotation reduced soil bulk density, hydrolyzable acid, exchangeable acid, exchangeable hydrogen and exchangeable aluminum by 4.00%, 20.51%, 27.92%, 10.00% and 37.14% respectively, increased soil porosity, organic matter, alkali-hydrolyzable N, available P, available K, pH, cation exchange capacity, base saturation, and soil buffer capacity by 9.17%, 13.97%, 7.22%, 12.06%, 5.08%, 5.15%, 35.27%, 15.44%, and 28.05%, respectively compared to flue-cured tobacco continuous cropping. The effects of combined application on the improvement of acid soil were better than those of single application of lime. The flue-cured tobacco and corn rotation system was more conducive to the improvement of acidified soil. The results of this experiment provided theoretical basis and practical guidance for the use of lime and planting green manure to improve the acid soil.

Abstract:This study investigated the physiological and ecological effects of exogenous NO ease Zizyphus jujube seedlings under salinity stress, intended to further understand the NO improved plant resistance and provide theoretical basis for the NO application in green cultivation of Z. jujube. Through nutritional hydroponic cultivation, the effect of exogenous NO on the polyamine, glutathione antioxidant enzymatic system and chlorophyll fluorescence features of Z. jujube seedlings was analyzed under four treatments:control (T1), 0.1 mmol/L SNP (T2), 100 mmol/L NaCl (T3), 0.1 mmol/L SNP+100 mmol/L NaCl (T4). Results showed that the 100 mmol/L NaCl treatment inhibit the growth of Z. jujube seedling, but addition of NO significantly relieved the effect of NaCl stress. Exogenous NO significantly increased the amount of putrescine (Put), polyamines (PAs), spermine (Spm), and spermidine (Spd) under the stressed condition. In addition, NO also increased leaf reduced glutathione (GSH) content, glutathione reductase (GR) activity and GSH/GSSG ratio, but slightly decreased the oxidized glutathione (GSSG) content. Meanwhile, the glutathione-S-transferase activity, the ascorbic acid (ASA) content, and the ascorbic acid peroxidase (APX) activity was increased. At the same time, NO treatment significantly improved the leaf PSⅡ maximum photochemical efficiency (F_v/F_m), PSⅡ potential active competency (F_v/F_o), apparent photosynthetic electron transport rate (ETR), actual photochemical efficiency (ΦPSⅡ), and photochemical fluorescence quenching coefficient (qP), but decreased the photochemical fluorescence quenching coefficient (qN).Through increment of polyamine content, activity of antioxidant enzymes and the content of non-enzymatic antioxidants, and reduction of photo inhibition and insurance of rational use of light energy, the application of exogenous NO relieves the NaCl stress on inhibition of growth and improves the salt resistance of Z.jujube seedlings.

Abstract:Through indoor incubation experiments, the effects of different application rates of biochar and lime on soil pH and cadmium (Cd) form in Cd-contaminated soil were studied. The results showed that the combination of biochar and lime could significantly increase soil pH, and these effects increased significantly with the increasing application amounts. With the increasing application amounts of lime and biochar, the exchangeable Cd decreased gradually. After 60 days of incubation, the exchangeable Cd contents in soil with a Cd concentration of 5 mg/kg was reduced by 36.80%, 49.12%, and 57.38%, respectively, compared with the control. The soil exchangeable Cd contents in the soil containing 20 mg/kg Cd was reduced by 29.27%, 31.68%, and 39.03%, respectively, compared with the control. The carbonate-bound Cd, iron-manganese oxide-bound Cd, and organic-bound Cd were increased in two soils. Although the residual Cd was increased, there were differences among different concentrations. Overall, under the conditions of this experiment, combined application of lime and biochar had better effect on the Cd inactivation in soil with a concentration of 5 mg/kg than that of a soil with a concentration of 20 mg/kg.

Abstract:The field experiments of two consecutive years were conducted with randomized block design with six treatments:spraying water (CK), spraying Bordeaux Mixture (BDM), spraying Kocide 2000 (KCD), spraying copper-based nutritional foliar fertilizer (CF), spraying iron-copper-based nutritional foliar fertilizer (CFFe) and spraying zinc-boron-copper-based nutritional foliar fertilizer (CFZnB), respectively. The effects on yield and quality, chlorophyll content and various indicators of photosynthetic characteristics of leaves, the plant and fruit total contents and accumulations of Cu, Zn and Fe, disease index of pepper and enzyme activities of soil were determined. The results showed that the CFFe, CFZnB, CF, and KCD significantly increased the photosynthetic rate, stomatal conductance, transpiration rate, and the chlorophyll content, in which the maximum increment was 20.13% by CFFe and followed by CFZnB that increased by 16.19%~18.13% as compared to the CK and significantly decreased intercellular CO₂ concentration in pepper leaves. The BDM, KCD, CF, CFFe and CFZnB significantly increased the plant and fruit total contents and accumulations of Cu. The CFZnB, CFFe, CF, and KCD significantly increased the plant and fruit total contents and accumulations of Zn. The CFFe, CFZnB, CF and KCD significantly increased the plant and fruit total contents and accumulations of Fe. The CFFe, CFZnB, CF, KCD and BDM greatly reduced the disease index at the early fruiting and full fruiting periods of pepper. Soil urease activities of the CFFe and CFZnB were the highest. All treatments and CK significantly increased the soil catalase activities as compared to the BDM. The CFFe, CFZnB, CF, and KCD significantly increased the soil sucrase activities as compared to the CK. Pepper nutritional quality of CFFe was the best and followed by the CFZnB. The CFFe, CFZnB, CF, and KCD significantly increased the yield of pepper, with the CFFe maximally increased by 13.22% and followed by the CFZnB that increased by 11.93%~12.52% as compared to CK. The CFFe, CFZnB, and CF significantly increased the yield of pepper, the CFFe was the most and followed by the CFZnB. The CFFe, CFZnB, and CF significantly improved the quality of pepper, pepper nutritional quality of CFFe was the best, the second was the CFZnB. Copper-based nutritional foliar fertilizer developed by Shandong Agricultural University, as a kind of bactericidal and plant nutrition health care double functional foliar fertilizer, can significantly increase yield and improve the quality of pepper, and has certain effect on prevention and control of pepper disease. Therefore, iron-copper-based nutritional foliar fertilizer and zinc-boron-copper-based nutritional foliar fertilizer are recommended.