Abstract:The construction of infrastructures such as highways always results in many exposed rock slopes. With the increasing awareness of human environmental protection, the higher requirement for environmental protection is being proposed. Therefore, as an important component of engineering construction technology, the biological protection of rock slope has obtained many achievements. Firstly, the features of vegetation restoration in rock slopes were analyzed. Secondly, the paper reviewed the application of biological protection technology in rock slopes, surface vegetation rational selection and design, the compound ratio of ecological base materials and their properties, the mechanism of vegetation restoration and its effect evaluation in China. Although much has been achieved, there are still many problems need to be deeply and systematically explored. The future studies may focus on the research and exploitation of biological protection in high-steep rock slope in special habitats, the interaction mechanism of rock slope-ecological base material-plant root system and its overall mechanical stability, constructing a long-term mechanism for the assessment and evaluation of the vegetation restoration and the establishment of technical specification for biological protection of rock slopes based on climate, geographical conditions.

Abstract:The different tillage depth of red soil slope farmland has an important effect on the quality of ploughing layer and crop yield. From the point of view of soil properties, the vertical depth soil moisture, bulk density, porosity, soil compactness, soil shear strength and soil organic matter under different tillage depth treatments in red soil slope cultivated land were studied in Jiangxi Province. Available phosphorus and available potassium were also analyzed. The results showed that:(1) The effects of different tillage depth on soil porosity, saturated water content and field water holding capacity were no tillage < tillage 20 cm < tillage 10 cm < conventional tillage < tillage 30 cm, the effect on bulk density was tillage 30 cm < conventional tillage < tillage 10 cm < no tillage < tillage 20 cm; compared with the conventional tillage, the soil saturated water content, field water holding capacity and soil porosity were increased by 18.17%, 12.67% and 5.94%, respectively after 30 cm tillage. Soil bulk density decreased 6.90%. (2) The soil compactness under different tillage depths was tillage 30 cm < tillage 10 cm < tillage 20 cm < no tillage < conventional tillage; soil shear strength was tillage 30 cm < conventional tillage < conventional tillage 10 cm < no tillage 20 cm. Compared with the conventional tillage, ploughing for 30 cm reduced soil compactness and shear strength by 27.07% and 24.82%, respectively. (3) The average content of soil organic matter was the highest under 20 cm tillage (13.48 g/kg), and lowest under no tillage treatment (9.39 g/kg). Soil available nutrients were mainly distributed in 0-20 cm soil layer. Compared with the no tillage treatment, soil available nutrients contents increased under the tillage treatments, among which tillage 20 cm and conventional tillage gave the significant differences. (4) The results of principal component analysis showed that the treatment of tillage 30 cm had the best effect on the comprehensive improvement of soil properties in red soil slope cultivated land. These results could provide reference for the improvement of ploughing layer soil and the construction of rational tillage layer in slope cultivated land of red soil.

Abstract:In order to prevent and control soil erosion during the thawing period, two typical small watersheds were taken as the research objects in the Hilly Area of Changbai Mountain in the Northeast Black Soil Region. Soil erosion, soil moisture (ω), soil temperature (T), soil shear stress (τ), soil reflected radiation (J) and local slope gradient (S) were observed during spring thawing period, and their corresponding effects on soil erosion were quantified, then the soil erosion prediction equation was developed. The results showed that soil erosion increased from the upslope, middle slope to the bottom slope; with the increase of the local slope gradients, soil erosion increased, but the increasing trend slowed down gradually; among the different aspects, southern slope had the largest soil erosion, and the northern had the smallest; and the differences were all significant (P<0.05). The factors affecting soil erosion were S, ω, τ, T and J, from large to small, during the thawing period. The prediction equation of soil erosion based on local slope gradient, soil moisture content and soil shear stress was developed (R²=0.903). This study would provide a scientific basis for soil erosion control during the thawing period.

Abstract:In order to study the response of native arbuscular mycorrhizal fungi (AMF) and intercropping patterns to nitrogen (N) forms changes in runoff on red soil, different planting patterns (mono-maize, maize/soybean intercropping, mono-soybean) and different mycorrhizal treatments (mycorrhizal inhibition, none mycorrhizal inhibition) were designed by simulating runoff experiment under natural rainfall. The migration characteristics of N of different forms in runoff under the combined treatments of mycorrhizal and intercropping were analyzed using the six runoff water samples collected from June to September in 2017. The results showed that during the sampling times, the total N concentrations in runoff increased firstly and then decreased, while the concentrations of nitrate N showed a trend of increasing firstly, then decreasing and increasing again, and the ammonium N concentrations decreased firstly and leveled off then. Under all combined treatments, the total N concentrations in runoff was the lowest under the intercropping-uninhibited treatment, which was about 35.0% and 42.1% lower than those of mono-maize and mono-soybean under mycorrhizal inhibition treatments respectively. Regardless of the planting modes, the concentrations of nitrate N in runoff under the uninhibited treatment was lower than that of the inhibited treatments, which were significantly lower than those of mono-maize and mono-soybean under mycorrhizal inhibition treatments, the reduction rate were 26.2% and 33.9% respectively. Regardless of whether the mycorrhizal inhibition was applied or not, the concentrations of ammonium N in runoff with intercropping treatment were lower than those of mono treatments, which was the lowest under intercropping-uninhibited treatment. Compared with mono-corn and mono-soybean under mycorrhizal inhibition treatments, the reductions were 34.8% and 28.2% respectively. These results indicated that native AMF and intercropping treatments had a certain synergistic reduction potential for runoff nitrogen loss on red soil.

Abstract:The aim of this research was to study the runoff process and total runoff characteristics of karst bare slope under different rainfall intensity and slope combinations. In this study, the caves and fissures in surface karst zone was regarded as a permeable "sieve hole". By setting the porosity (fissure) of the underground "dualistic structrue" structure to be the same (5%), the characteristics of surface/subsurface runoff process and total runoff on bare slopes under different rainfall intensity and gradient combinations were studied. Then, the effects of various factors on the hydrological characteristics of karst slopes were discussed. (1) Under the small rainfall intensities (15 and 30 mm/h), the runoff on bare slope was primarily dominated by the subsurface runoff without surface runoff. But, under the heavy rainfall intensity (≥ 50 mm/h), the surface runoff occurred, which process did not change regularly within 30 minutes of the designed rainfall; however, the subsurface runoff process increased first and then leveled off under all different slope and rainfall intensities, and the turning points were mostly in 9~12 minutes. (2) The differences of total subsurface runoff were not significant (P>0.05) in 5°, 10°, 15° and 20° slopes under the rainfall intensity of 15 mm/h in 30 minutes, while the surface/subsurface runoff had significant differences with the increase of slope gradients (P<0.05). All the surface/subsurface runoff was positively correlated with the rainfall intensities and slope gradients (P<0.01), except that the total subsurface runoff was negatively correlated with the slope gradients (P<0.01). (3) The subsurface runoff coefficient was less than 0.5 for the first time under the heavy rainfall intensity (90 mm/h), which proved that there was a critical gradient which made the surface and subsurface runoff equal to each other. These research results can provide reference and reasonable suggestions for the prevention and control of soil erosion in Karst slopes.

Abstract:ln order to explore the soil anti-scouribility under different vegetation planting modes and find out the best vegetation planting patterns for soil and water conservation in red soil region, the soil under different planting modes in red soil hilly region was selected as the research object. The soil anti-scouribility under three different scouring flow (1.5, 2.5, 3.5 L/min) was studied by wet screening method and the undisturbed soil sample washing experiment. The results showed that:(1) The coefficients of soil anti-scouribility under different vegetation planting patterns ranged as:stripe grass shrub belt > geomantic forest > planting grass on the whole slope > mango rake land > closure land > bare land > reclaimed land. The scouring sediment yield of the three scouring flows was in a low level equilibrium state. The scouring sediment yield ranged from 0.01~1.12, 0.02~1.53 and 0.02~2.57 g, respectively. CK1 and CK2 had the largest scouring sediment yield, ranging from 0.08~65.20, 0.07~60.56 and 0.24~80.60 g, respectively. (2) Soil total porosity,>0.25 mm water-stable aggregates content, root surface area, root volume, root length and root biomass in trench grass irrigation belt and geomantic forest accounted for 37.08%, 80.38%, 44.15%, 45.12%, 52.11% and 57.91% of all modes respectively. (3) The average weight diameter (MWD), geometric mean diameter (GMD) of soil aggregates, root length density and root weight density were the larger in the shrub belts and geomantic forests, accounting for 55.76%, 44.06%, 52.18% and 54.91% of all modes, respectively. The results could provide reference for controlling soil erosion and revealing the mechanism of erosion in red soil region.

Abstract:Aiming at the problems instability of collapsed hill soil deveoped by granite, the tensile strength characteristics of collapsed hill soil with different initial water contents were studied by uniaxial tensile test in Tongcheng area of Hubei Province. The results showed that the initial moisture contents had a significant effect on the tensile strength of the collapsed soil. The characteristic curve of soil tensile strength appeared as a unimodal curve. The peak values were obtained at the water content of W_C(24.4%) for the surface soil, laterite and red sand transition layer, while W_C(25.8%) for the sandy layer. The axial and radial shrinkage lengths of different soil layers were positively correlated with the initial water contents, and the linear relationships between the axial and radial shrinkage of soil and the initial water contents were fitted with a higher correlation coefficient (the radial shrinkage of sand removal layer is exponentially correlated with the initial water contents). The mechanisms of water holding in soils with three initial water contents ranging from low (18%~22%), medium (22%~30%) to high (30%~saturation) was analyzed, which were soil capillary water holding mechanism, aggregate water bridge water holding mechanism and aggregate water holding mechanism respectively. These research results could provide a scientific basis for the scientific prevention and control of collapsed hill.

Abstract:In order to reveal the erosion characteristics under different land use types in Jianshan River watershed in central Yunnan Province, the soil in different soil layers (0-10, 10-20 and 20-30 cm) under four different land use types (sloping farmland, bare land, forest land and garden land) was taken as the research object. The effects of different land use types on soil erosion resistance were studied by measuring and analyzing 15 soil erosion resistance indexes. The results showed that the contents of>5 mm water-stable aggregates in sloping farmland and bare land were significantly lower than those in forestland and garden land. The content of>5 mm water-stable aggregates in sloping farmland (12.72%) was higher than that in sloping farmland (8.93%), and the contents of>0.25 mm aggregates in sloping farmland decreased with the increase of soil depth. The structural failure rate of soil aggregates was bare land > sloping farmland > forest land > garden land. The soil organic carbon contents were significantly positively correlated with the contents of>0.25 mm water stable aggregates. Under different land use types, forest land and garden land had the highest corrosion resistance index, structure coefficient, agglomeration degree, soil structure and stability, dispersive strength, water and fertilizer retention capacity, the larger water stability index, the smallest dispersion coefficient and the strongest corrosion resistance. The order of the comprehensive corrosion resistance index of different land use types was garden land (0.823 6) > forest land (0.520 4) > sloping farmland (-0.382 2) > bare land (-0.961 8). In conclusion, artificial afforestation could significantly improve the structural stability of the original soil, and garden land and forest land had obvious advantages in increasing soil erosion resistance. Strengthening plantation construction could be an effective measure for soil improvement in the study area.

Abstract:Plateau zokor is the dominant subterranean rodent in Qinghai-Tibet plateau and it burrows soil of the ground surface to form new mounds,which is a kind of bare land that easily causes soil erosion. It is of great significance to study soil erosion of new mounds caused by plateau zokor to evaluate the impact of the zokor on alpine meadow ecosystem. This study used the runoff plot method and the wind erosion bridge method to determine the annual soil erosion and organic matter loss on the new mounds, and compared the soil particle composition, soil moisture and soil nutrients contents between the new mounds and the surface soil (0-10 cm) on the grassland without mounds. The purpose was to clarify the soil erosion of the new mounds on different topography, including plain and slope, as well as different size new mounds, involving large (diameter>75 cm), moderate (diameter 50~75 cm) and small (diameter<50 cm). The results showed that:(1) In plain and slope area, the annual soil loss of plateau zokor mounds was 4 039.91 and 3 731.79 g/m² respectively, and the annual soil organic matter loss was 266.83 and 252.76 mg/m² respectively. The soil erosion level of plateau zokor mound was moderate; (2) Both the contents of soil aggregates with size of<0.25 mm and>5 mm in mounds surface were significantly less than that of grassland without mounds (P<0.05), and the soil aggregates contents of>0.25 mm in mounds surface was significantly greater than that of grassland without mounds(P<0.05); (3) The soil fertility and soil moisture of mounds' surface soil were significantly less than that of grassland without mounds (P<0.05); (4) The amount of sediment loss of new mounds on the slope was significantly higher than that of the plain in the rain season (P<0.05). The wind erosion of zokors' mounds on the plain was greater than that on the slope in the wind season, the thickness of wind erosion on the plain and slope was 4.33 and 3.62 cm, respectively; (5) The thickness of wind erosion of different size mounds in the wind season was highest on the large mounds, followed by small mounds and moderate mounds. The thickness of wind erosion of large, moderate and small size mounds were 5.50, 3.59 and 2.82 cm, respectively. In conclusion, the new mounds of plateau zokor could cause wind and water erosion, which level depends on the different topography and mounds size, in alpine meadows.

Abstract:Soil erosion is one of server global environmental problems, soil erosion survey is the scientific basis for soil and water conservation. In order to improve the methods applied in soil erosion sampling survey, and to calculate soil erosion rates accurately and rapidly, the interpretation methods for land use and soil conservation measures were studied based on the high spatial resolution remote sensing images. The sampling design was developed using a stratified variable probability systematic sampling method in which spatiotemporal characteristics of soil erosion and conservation were derived based on the GISci, virtual global tool, and finer resolution images accessible in Google Earth. Land use and soil conservation measures in the sampling units were interpreted from the open access, high-resolution remote sensing images using visual interpretation. More than 20 thousand sampling units were interpreted, then the information on the land use and soil conservation measures was extracted; the soil erosion rate was calculated using CSLE for some of the units, and the accuracy and applicability of the interpretation results were analyzed. The results showed that this sampling survey method could be used for the soil erosion survey in the very large region. The information about land use and soil conservation measures could be interpreted based on open access, fine resolution remote sensing images, and the stratified variable probability systematic sampling method.

Abstract:In order to study the effect of temperature changes on soil water characteristic curve, the water characteristic curves of red soil and paddy soil in South China were measured by high-speed centrifuge at 4, 12, 20, 28 and 36℃ respectively. The parameters were extracted by VG model, and the effects of temperature on soil equivalent pore size distribution, unsaturated hydraulic conductivity and water diffusivity were discussed. The results showed that the water contents of red soil and paddy soil decreased significantly with the increase of temperature under the same water potential (P<0.05), appearing as 4℃ > 12℃ > 20℃ > 28℃ > 36℃. The water holding capacity of red soil was significantly higher than that of paddy soil (P<0.05) at the same temperature. Under different temperature treatments, unsaturated hydraulic conductivity and water diffusivity of red soil and paddy soil showed the significant difference that the highest value was observed at 20℃ and the smallest at 36℃ (P<0.05), which indicated that the water conductivity and infiltration capacity of red soil were relatively optimal at 20℃. The unsaturated hydraulic conductivity and water diffusivity of red soil were lower than those of paddy soil at the same temperature. The saturated moisture content θ_s of red soil and paddy soil, the relative parameters of air intake value α, and the shape coefficient n all decreased slowly with the increase of temperature, and the fitting parameters were significantly different with the changes of temperature (P<0.05), which indicated that the parameters of soil water characteristic curve were sensitive to temperature. The results of this study could provide a reasonable reference for further exploring the effect of temperature on soil water holding capacity and water transport mechanism in southern China.

Abstract:In order to study the spatial distribution characteristics of soil moisture in Sabina vulgaris Ant. community, this paper took the vegetation of Sabina vulgaris Ant. in the southern edge of Mu Us as the research object. Ten plots were selected and soil samples were taken by cutting ring. The soil moisture content and water storage were measured and analyzed by soil drying method. The following results were obtained:(1) There were significant differences among the soil moisture contents in the plots with different slope positions (P<0.05). Soil moisture content and water storage were lower of dune > middle dune > lowland among sandy dune > sand ridge, middle dune > lower of dune > lowland among sandy dune > sand ridge. (2) There were significant differences among soil moisture contents under different slopes (P<0.05). Both soil moisture content and water storage showed that leeward slope>windward slope. (3) There were significant differences among soil moisture contents under the influence of vegetation inside and outside the forest (P<0.05). Both soil moisture content and water storage were grassland > Sabina vulgaris Ant. > Sand. These results showed that Sabina vulgaris Ant. Community had certain influence on spatial distribution of soil moisture.

Abstract:The soil moisture of ephemeral gully in Hegou watershed at Wuqi county in Loess Area of Northern Shaanxi was taking as the research object. The spatial distribution characteristics of soil moisture in different ephemeral gullies with different depths, different slope aspects and different slope positions were studied. The results showed that:(1) According to the relationship between ephemeral gully and the growth of Pinus tabuliformis Carr. on the original slope, the ephemeral gully was divided into deep ephemeral gully (40 cm ≤ depth) and shallow ephemeral gully (20 cm ≤ depth <40 cm). (2) The soil moisture of the ephemeral gully was higher than that of the original slope; the soil moisture of the ephemeral gully was concentrated in the 0-60 cm soil layer, while that of the original slope was concentrated in the 0-40 cm soil layer. (3) The soil moisture variation degree was differeat in the different soil layers in ephemeral gully. The soil moisture variability of sunny slope was smaller than that of shady slope. In 20-60 cm soil layer, the soil moisture variability coefficient was larger, soil moisture was more active, and the soil moistures in other soil layers were less variable and more stable. (4) There were significant differences in soil moisture among ephemeral gullies with different slope positions, different slope aspects and different depths. In shallow ephemeral gully, soil moisture followed the order of lower slope > upper slope > middle slope, while in deep ephemeral gully, the order was upper slope > lower slope > mid slope. In ephemeral gully, soil moistures in the middle and lower position of the shady slope were significantly higher than that of sunny slope, and the soil moisture on the upper position of sunny slope was higher than that of shady slope. The soil moisture of the original shady slope was significantly higher than that of sunny slope.

Abstract:Taking the typical lime soil in Karst area as the research object, the indoor one-dimensional fixed head method was used to simulate the soil column. Four activated carbon concentrations (0, 0.005, 0.01 and 0.02 g/g), two mixed application methods (0-10, 10-20 cm) and three layered application methods (6-8, 10-12 and 16-18 cm) were used as variables. To observe the dynamic process of soil wetting front movement and cumulative infiltration, the linear relationship and van Genuchten empirical formula were used to simulate the movement of wetting front and the empirical formula of water characteristic curve, respectively, and the mass water contents of different soil layers were measured to study the effect of activated carbon powder on soil infiltration process. The results showed that:(1) In the same infiltration time, compared with other experimental groups, the higher concentration (0.02 g/g) and the shallow application mode (0-10 and 6-8 cm) were better in slowing down the moving speed of soil column wetting front. (2) At the early stage (t<80 min), the inhibition degree of infiltration by activated carbon powder was positively correlated with its concentration, but the high concentration of carbon powder could slow down the movement rate of wetting front at the same time. Therefore, the final infiltration amount (t<340 min) was less affected by its concentration, and affected by the physical and chemical properties of activated carbon powder. The slope increased at the later stage of layered laying infiltration. (3) The simulation of soil infiltration parameters by van Genuchten empirical formula and RETC software showed that the concentration of activated carbon powder was positively correlated with the ability of soil to absorb water, and it was negatively correlated with soil water release capacity. (4) Activated carbon powder increased soil field water holding capacity and wilting coefficient, and the higher the concentration of activated carbon powder, the greater the field water holding capacity. (5) Under the condition of layer application, the activated carbon powder could increase the mass water content of the soil layer, but had little effect on the water content of other deep soil layers.

Abstract:Using organic fertilizer, water-retaining agent (polyacrylamide PAM, polymer water-absorbent resin SAP and Water) as test materials, the effects of organic fertilizer combined with water-retaining agent on water infiltration and nitrogen leaching of purple soil were studied through indoor soil column simulation test. The results showed that organic fertilizer combined with water-retaining agent could effectively increase soil water and fertilizer retention capacity, and was an effective measure to control soil water and nutrient leaching. Single application of organic fertilizer and application of organic fertilizer combined with water-retaining agent both could reduce the wetting front migration depth and infiltration rate. Compared with the control, the wetting front migration depth of the above two treatments decreased by 33.33%~46.49%, the infiltration rate decreased by 22.73%~31.82%, and the cumulative leaching solution volume decreased by 1.25%~6.78%. The application of organic fertilizer had a certain fertilizer-preserving ability, but the fertilizer-retaining capacity gradually decreased with the increasing of leaching times. Compared with the control, the cumulative loss rates of nitrate nitrogen and total nitrogen increased by 12.00% and 17.51%, respectively, under continuous leaching. Organic fertilizer combined with water-retaining agent could effectively reduce nitrogen leaching amount and nitrogen leaching rate, and improve soil fertility retention capacity. Compared with the application of organic fertilizer, the nitrate loss rate and the total nitrogen loss rate of organic fertilizer combined with water retention agent treatment decreased by 35.49%~78.46% and 35.53%~71.85%, respectively. Among them, organic fertilizer combined with PAM had the best effect of water retention and fertilizer retention.

Abstract:Plant root system is the channel of material exchange between vegetation and soil. In the loess hilly area with serious soil erosion and fragile ecology, it is great significance to deeply understand the influence of root system on soil physical and chemical properties. In this study, six plant species were taking as research objects, which were Bothriocheloa ischaemum, Carex lanceolata, Artemisia leucophylla, Artemisia gmelinii, Sophora viciifolia and Caragana intermedia. Roots and soil samples of 0-10, 10-20, 20-30, 30-40, 40-50 and 50-60 cm soil layers were taken. The root length density, root surface area density, mean root diameter, soil organic matter, soil bulk density and water stable aggregate content of each species in each soil layer were analyzed. The results showed that the roots of the species studied were mainly fine roots. In the 0-20 cm soil layer, the root length density of herbaceous plants was significantly higher than those of other species (P<0.05), which followed the order of B. ischaemum > C. lanceolata > A. leucophylla > A. gmelinii > S. viciifolia > C. intermedia, while the average root diameter was opposite. The root system could increase the SOM content in varying degrees, and the SOM content had a significant positive correlation with the root mean diameter and root surface area density(P<0.01). In the soil profile, the weight percentage of water-stable aggregate significantly decreased in the sample plots of B. ischaemum, C. lanceolata and A. sacrorum. The weight percentage of water-stable aggregates did not change significantly with depth in the sample plots of A. leucophylla, S. viciifolia and C. intermedia. Root surface area and root length density could significantly increase the weight percentage of water-stable agglomerates of 0.5~2 mm (P<0.05), which indicated that the root system could agglomerate small-size aggregates into larger-size soil aggregates. The above research results showed that root system could increase soil organic matter content and medium-size aggregate content, improve soil structure and soil stability, and played an important role in increasing soil corrosion resistance.

Abstract:Taking the Wind-breaking and Sand-fixing Forest System in Jilantai Salt Lake as the object, the physical and chemical properties of soil in different parts were investigated to evaluate the effect of the Wind-breaking and Sand-fixing Forest System, and provide a theoretical basis for vegetation restoration in arid areas. The results showed that:(1) After 35 years of construction of the Wind-breaking and Sand-fixing Forest System in Jilantai Salt Lake, the original quicksand texture changed significantly under the joint effect of intercepting wind erosion material and vegetation improvement. Compared with the moving dune, the contents of fine sand and powder in the targeted soil increased significantly (30.55% and 500.00%, respectively), while the coarse sand contents decreased by 27.00%. (2) The soil organic matter, available nitrogen and total nitrogen contents in the shelterbelt were very high, which was 252%, 665% and 1 466% of the moving dune. The difference of total phosphorus was not obvious. The contents of available phosphorus and available potassium in the lake were the highest, which were 276% and 202% of the moving dune, respectively. The highest total potassium content was observed in the transition zone with white thorn bushing, which was 153% of the moving dune. In general, the nutrient contents showed a positive correlation with medium sand, fine sand, very fine sand and powder. (3) Soil organic matter, total available nitrogen, and potassium could comprehensively reflect the soil quality improvement effect of the shelterbelt system, and the soil in the shelterbelt had the highest comprehensive soil nutrient contents. After 35 years of development, the soil available nitrogen, total nitrogen and organic matter in the shelterbelt increased by 204.20%, 90.63% and 94.11%, respectively, indicating that the Wind-breaking and Sand-fixing Forest System had an obvious improvement effect on soil. These research results could provide data support for evaluating the protection benefits of the wind-fixing and sand-fixing forest system in Jilantai Salt Lake.

Abstract:Taking the 1~5 mm straight roots of Caragana microphylla as the research object, the effects of 50 times of loading (70% of the ultimate tensile-shear combined force of the test roots) on the mechanical properties were studied using TY 8000 servo-type strength machine. The results showed that the slope of the ultimate force-radial displacement curve of the test roots was larger than that of the control after 50 times of loading, and the ultimate tensile-shear combined force and strength of the test roots were significantly higher than thsoe of the control roots (p<0.05). After repeated loading, both the function relationship between the combined tensile and shear forces and diameters and the function relationship between the combined tensile and shear strength and diameters of the test roots were similar to those of the control, but still showed a positive and a negative power function correlation, respectively. With the increase of root diameters from 1~2 mm to 4~5 mm, the ultimate tensile-shear combined force of test roots increased from 1.26 to 1.34 times of the control. With the increase of loading times, the increment of radial displacement of test root decreased.

Abstract:As an important indicator for soil structure, soil aggregates have a huge impact on soil porosity and water holding capacity. Soil aggregate organic carbon can not only reflect soil carbon sequestration capacity, but also be closely related to aggregate stability. Study on soil aggregates and organic carbon distribution characteristics in Chinese Fir plantations can provide theoretical basis for improving soil productivity and water use efficiency. In our research, soil samples were collected from Chinese Fir plantations with different forest ages (6, 11 and 32 years), which was located in Yangkou National Forest Farm, Fujian Province, China. The water-stable soil aggregate composition and organic carbon contents were measured. The results showed that forest age was very important in terms of soil aggregate and its organic carbon. Macro-aggregate contents (>0.25 mm), MWD, organic carbon contents and its contribution of aggregates in mature forest were higher than that in young and middle forests. Water-stable macro-aggregates were the main part of soil aggregates, which accounting for about 59.57%~80.97%, while the aggregates with the partical size less than 0.053 mm only accounted for 0.80%. In terms of organic carbon contribution, macro-aggregates were the main contributor, and aggregates with the partical size 2~0.25 mm accounted for 58.43%. Furthermore, soil aggregate MWD and its carbon content had a typically vertical characteristic, decreasing with soil depth. A strong positive correction was found between aggregate MWD and organic carbon. Hence, organic carbon was beneficial for the stability of soil aggregate, and MWD and organic carbon contents of aggregate showed a trend as mature forest > young forest > middle forest.

Abstract:Fire disturbance is one of the important factors affecting the structure and function of forest soil ecosystem. In order to provide theoretical guidance for forest regeneration and sustainable management after fire disturbance, this study explored the dynamic characteristics of physiochemical properties in forest soil after different fire disturbances. The effects of fire intensities (control, low, moderate and high intensity fire) and time nodes (3, 30, 180, 360, 720 days after fire) on bulk density (BD), soil water repellency (SWR), soil organic matter (SOM), pH, total nitrogen (TN), total phosphorus (TP) and total potassium (TK) contents were measured in a field-scale experiment with 16 plots (20 m×20 m) from Liquidambar formosana secondary forests in Zhuzhou, Hunan Province, China from 2014 to 2016. The differences and changing trends of soil properties among different fire disturbances at the same time node and different time nodes under the same fire disturbance were studied by descriptive statistical analysis, one way ANOVA and Fisher LSD test (p<0.05). The result showed that BD, SWR, pH, and TK increased with the increase of fire intensities, while SOM and TP decreased after the fire disturbance at the same time node. There was no significant difference of TN among different fire disturbances. Compared with the control, the effects of low intensity fire on BD, SWR, pH and SOM were not significant at the same time node, the effects of moderate intensity fire on these soil physiochemical properties were significant at some time nodes, while the effects of high intensity fire on them were significant. After the same intensity of fire disturbance, there were significant differences in BD, SWR and pH among different time nodes (p<0.05). BD, SWR and pH increased significantly at the first three days after fire, then decreased gradually; BD returned to pre-fire level after 360 days of fire, while SWR and pH needed 720 days after fire. However, there were significant differences of SOM between 360, 720 days and other time nodes only after high intensity fire. After fire disturbance, SOM decreased first, then increased gradually, and returned to the level before fire and maintained stability after 360 days. After fire with moderate and high intensities, the greater the time span was, the more significant the difference of TK was, while the differences of TN, TP were only significant after high intensity fire. Fire intensities and time nodes had certain effects on the studied soil properties, among which high intensity fire showed the biggest effects on soil properties. Fire disturbance caused soil fertility decline in the short time and affected the soil nutrient status of forest land. However, with the time went on, the properties of soil physiochemical gradually recovered to the pre-fire level after two years.

Abstract:The land use changes caused by the Karst Rocky Desertification Comprehensive Control and Restoration Project change the underlying surface conditions, such as vegetation cover, and then affect the ecosystem services. In order to identify the changes of ecosystem services, the spatio-temporal changes of supply and demand of water, food and carbon services were explored based on InVEST model, CASA model and multiple methods in Xiaojiang Basin during 2005-2015. The results showed that:(1) The supply of water, food and carbon services showed a significantly increasing trend during 2005-2015, with a growth rate of 14.34%, 44.00% and 40.11%, respectively. The demand of water and carbon also showed a significantly increasing trend, with a growth rate of 3.26% and 61.54%, respectively while food showed a decreasing trend, with decrease rate of 6.98%. (2) The supply-demand ratio of water and food services were increasing and greater than 0, while carbon was decreasing in 2015. (3) The larger area of rocky desertification was, the lower the food service was. With the aggravation of rocky desertification, the water and carbon services decreased. With the decreasing area of rocky desertification, the changes of water and carbon services were not significant, and the food services increased. The larger the changing area was, the more significant the trend was. By analyzing the supply and demand of ecosystem services and the relationships with rocky desertification in Xiaojiang Basin, it could provide important advice for the management of regional ecosystems and the comprehensive management of rocky desertification.

Abstract:Forests in the alpine gorge area of western Sichuan may have higher hydrological ecological benefits due to the higher reserves of forest litter, but scant research is available. Therefore, the water-holding and water-loss characteristics of the forest litter in six types of forests in this region were investigated during the rainy season. The results showed that:(1) The forest litter storage had a significant positive correlation with the maximum water-holding capacity and modified interception amount in the alpine gorge region of western Sichuan. The forest litter storage, maximum water-holding capacity, maximum water-holding rate, modified interception amount and modified interception rate were 6.90~17.49 t/hm², 1.64~5.42 mm, 138.18%~330.09%, 0.53~3.33 mm and 77.57%~203.02%, respectively. (2) Compared with other forests, the litter of Betula luminifera-Rhus potaninii forest had the best water holding characteristic, while the litter of Quercus baronii-Sophora davidii-Cotinus coggygria forest had the worst. (3) The cumulative water-holding capacity and cumulative water loss capacity of forest litter varied logarithmically with increasing soaking time and water loss time, respectively. But the water absorption rate and water loss rate showed a remarkable power function relationship with soaking time and water loss time, respectively. The forest litter in the alpine gorge area of western Sichuan had obvious function of absorbing and intercepting rainfall during the rainy season, and the best one was B. luminifera-R. potaninii forest in this region. These results provided reference basis for forest ecological construction and the ecological benefit evaluation in the alpine gorge area of western Sichuan.

Abstract:The objective of this study was to investigate the effects of fire-derived black carbon on soil extractable nutrient elements in subtropical plantations. Three levels of black carbon input were applied to the experimental plots (10 m×10 m) by removing charred materials across the plots two weeks after slash burning in a Pinus massoniana Lamb. plantation. The three levels of black carbon were:B0, in which all visible charred materials were carefully removed from the plot; B1, in which all charred materials were left in place on the forest floor; and B2, in which all charred materials removed from the B0 plots and the double quantities of charcoal inputs were added. Soil samples were collected from 0-10 and 10-20 cm depth 1 year after charcoal application or removal. The results showed that:(1) The impact of black carbon input on soil major nutrients varied with sampling depth. At 0-10 cm depth, the contents of potassium(K), calcium (Ca) and magnesium (Mg) in B2 soils were significantly higher than those in B0 soils (P<0.05), which differences were not observed at the 10-20 cm depth. Available phosphorus (P) contents in B2 soils were significantly higher than those in UB soils at both 0-10 cm and 10-20 cm depth (P<0.05). (2) The amount of black carbon input had no effect on soil minor nutrients (P>0.05). Double the quantities of black carbon input significantly increased manganese (Mn) content compared with the UB soils (P<0.05). (3) There was no significant differences of soil SPAR, Ca/Al, and Ca/Mg except for Ca/Mg at the 10-20 cm depth, where Ca/Mg in B2 soil was significantly higher than those in B0 and B1 soil(P<0.05). In summary, our findings highlighted the importance of black carbon to improve soil fertility and structural stability in subtropical plantations subjected to slash burning in the short term. Future research should focus on the long-term impacts of black carbon on soil nutrient availability in subtropical plantations subjected to slash burning.

Abstract:In this study, the isotope spectrometer was used to observe the nighttime CO₂ concentration and δ¹³C during the vigorous growth period of Platycladus orientalis plantation in Beijing mountainous area. The difference of nocturnal respiration δ¹³C of different components of the P. orientalis ecosystem was analyzed, and its response to environmental factors was explored. The results showed that when using the Keeling plot method to fit the δ¹³C released by the nocturnal respiration in the P. orientalis plantation from July to September, the fitting accuracy improved from 0.43 to 0.82 and the error decreased from 0.54~0.99 to 0.50~0.82 after the atmospheric stability was used as the screening condition. The variation range of δ¹³C was (-28.76±0.51) ‰~(-25.18±0.59) ‰, which showed a trend of increasing first and then decreasing. The above-ground variation range of the aboveground arborvitae branch δ¹³C was (-33.16±1.08) ‰~(-26.82±0.18) ‰, and showed an increasing trend, reaching its maximum at the end of July, and tended to be stable in September. The underground variation of δ¹³C in the underground soil was (-28.55±0.17) ‰~(-21.39±0.37) ‰, and showed an increasing trend, reaching the maximum in July, as well as the variation was the largest, and the change was stable in September. The relationship between δ¹³C in each month and time was quadratic function. During the vigorous growth period, the night soil respiration flux accounted for 54.77% of the ecosystem respiratory flux, and the underground δ¹³C was 2.06‰~7.03‰ higher than the aboveground δ¹³C. Stepwise regression analysis showed that the nocturnal respiration δ¹³C was significantly affected by atmospheric humidity. The contribution rate of the atmospheric humidity to the variation of carbon isotope value of each component was more than 60%. The underground δ¹³C was not affected by the soil temperature. Except for atmospheric humidity, the atmospheric temperature and soil temperature and humidity had relatively balanced effects on the aboveground δ¹³C. Through the study of night respiration δ¹³C, it was possible to evaluate more comprehensively the carbon balance of forest ecosystems in Beijing mountainous area, and provide a scientific basis for regional forest ecosystem management.

Abstract:Reasonable tillage and fertilization methods are important measures to achieve the high yield and high efficiency of crops. The research work was conducted to explore the effects of different tillage and fertilization methods on nitrogen (N) utilization, yield and soil bulk density of summer maize. In 2016-2017, three treatments of tillage and fertilization were designed, including T1 (no-tillage + upper application of NPK), T2 (subsoiling + whole layer application of NPK) and T3 (application of N, P, K fertilizers to designated different soil depth with subsoiling). Compared with T1, the dry matter accumulation and total N accumulation of T2 and T3 at the mature stage increased by 9.68% and 13.97%, respectively, and the average yield of summer maize enhanced by 17.20%. Compared with T1, the N production efficiency and agronomic efficiency of T2 and T3 improved by 14.74% and 59.95%, respectively, and the apparent N utilization efficiency increased by 14.15% on average, while the soil bulk density of 0-40 cm decreased by 8.54%. Under the deep pine cultivation method, compared with T2, the dry matter and total N accumulation of T3 at the mature stage increased by 9.41% and 6.28%, respectively, and the average grain yield raised by 9.70%, the N production and agronomic efficiency of T3 increased by 8.59% and 32.32%, respectively, and the apparent N utilization efficiency increased by 14.10%. Compared with T1, T2 and T3 increased the yield of summer maize and the utilization of N fertilizer and significantly reduced soil bulk density. The combination of controlled release N fertilizer and deep pine with two-fertilizer ectopic stratified fertilization (T3) could more effectively reduce soil bulk density, increase grain yield and N use efficiency. It is a new type of tillage and fertilization method recommended of summer maize production in the Huanghuaihai Plain.

Abstract:To evaluate the water conservation function of Betula luminifera plantations with different ages in Northwestern Guangxi, the representative 11 and 16-year-old B. luminifera plantations and 16-year-old Cunninghamia lanceolata were selected as main research object, and the water conservation capacities in three layers including the forest canopy, litter layer and the soil layer, as well as the comprehensive water conservation capacity were analyzed quantitatively. The results showed that:(1) The water holding capacity of the canopy, shrub layer and herb layer of the 11 and 16 year-old B. Luminifera plantations ranged from 12.54 to 21.06 t/hm², 2.15 to 3.05 t/hm² and 1.27 to 1.52 t/hm². The total litter reserve was 4.54~7.42 t/hm², and the maximum water holding capacity was 12.55~16.00 t/hm², which of 16-year-old plantation was significantly higher than that of 11-year-old plantation (P<0.05). There was a good linear relationship between the water absorption rate and water soaking time (R²>0.86, P<0.05). (2) The pore condition of soil followed the order of 16-year-old B. Luminifera forest > 11-year-old B. Luminifera forest > 16-years-old C. lanceolata forest, and the pore condition of soil was significantly higher in 0-20 cm soil layer than that in 20-40 cm and 40-80 cm soil layer. (3) The variation range of maximum water holding capacity, capillary water holding capacity and non-capillary water holding capacity of the 11-year-old B. Luminifera soil was 28.97%~60.55%, 25.35%~47.21% and 3.71%~13.34%, and the range was 26.06%~63.45%, 25.63%~48.70% and 3.34%~14.75% in 16-years-old B. Luminifera plantation, respectively, and all the values decreased with the increasing of the soil layer. The natural water content ranges of 0-80 cm soil layer in 11 and 16 year-old forest were 27.46~30.16 g/cm³ and 28.12~30.22 g/cm³, respectively, and total water storage capacities were 3 813.4 t/hm² and 3 732.2 t/hm², respectively, and all the values were greater than those in 16-year-old C. lanceolata forest (3 659.2 t/hm²). On the whole, the older B. luminifera plantation had stronger water conservation function, and it was superior to the same age C. lanceolata plantation. The results could provide scientific basis for the management of B. luminifera plantation in this area.

Abstract:The effects of calcium level on calcium absorption and utilization, fruit quality and yield of infinite growth tomato were studied by using the integrated technology of water and fertilizer in substrate cultivation with different levels of calcium nutrition (0, 1, 3 and 6 mmol/L). The results indicated that the distribution of calcium in different parts of tomato plant was very uneven, and the calcium content of the same part varied greatly in different periods. The distribution and change of calcium in plant were affected by the level of calcium nutrition and temperature. With the increasing of calcium level, the calcium content of tomato fruit increased continuously, and calcium deficiency would reduce the yield and quality of tomato fruit. Although there was antagonistic relationship between calcium and K, Mg, P, N, high calcium would not cause the decline of fruit yield and quality. High temperature could induce calcium deficiency symptoms and umbilical rot of fruit, which seriously affected the yield and quality of tomato. High calcium treatment had a certain mitigative effect on high temperature stress.

Abstract:Soil enzymes actively participate in the biochemical processes of soil systems and are the key link to the "plant-soil enzymes-soil nutrients". In order to investigate the effects of vegetation types on soil nutrient and enzymes activities in the hilly region of the Loess Plateau, four typical vegetations (grassland, Xanthoceras sorbifolia, Caragana korshinskii shrub, and Hippophae rhamnoides) in the loess hilly region were studied. Soil samples of 0-10, 10-20 and 20-40 cm layers were sampled to determine and analyze the changes of soil nutrient (carbon, nitrogen, phosphorus) and soil enzymes activities (sucrose, urease, catalase, amylase). The results showed that the soil organic carbon and total nitrogen contents in the 0-40 cm layer of the Xanthoceras sorbifolia were 19.42% and 35.15%, 82.98% and 40.49%, 67.27% and 24.12% higher than those of the grassland, Caragana korshinskii shrub, and Hippophae rhamnoides respectively. With the increase of soil depth, the contents of soil organic carbon, total nitrogen and total phosphorus showed a "increase first and then decrease" change in Caragana korshinskii shrub, but gradually decreased under the other three vegetation types. The soil amylase, urease and sucrase activities were significantly different among the four vegetation types (P<0.05), and the soil enzymes activities decreased with the increase of soil depth. The maximum value of soil amylase was found in the grassland, the maximum values of urease and sucrase activities were in Xanthoceras sorbifolia, and the lowest values of the three enzymes were found in Caragana korshinskii shrub. Correlation analysis showed that soil organic carbon contents were significantly positively correlated with total nitrogen, sucrase and urease activities (P<0.01). There was a significant positive correlation between soil total nitrogen contents and urease activities at 0.01 level, and a significant positive correlation between total phosphorus contents and sucrose activities at 0.05 level. Soil total phosphorus contents were negatively correlated with nitrate nitrogen contents (P<0.01), positively correlated with sucrose (P<0.01) and amylase activities (P<0.05). Therefore, vegetation type is an important factor affecting soil enzymes activities and nutrient changes in the Loess Plateau.

Abstract:Anaerobic soil disinfestation (ASD) as an alternative chemical fumigation of soil, has been gradually popularized in various places. However, effects of ASD is dependent on types of soil and amendments added. A field experiment was conducted to study the effects of ASD with different amendments on soil properties and microbial community, which would provide a scientific basis for environmentally friendly soil disinfestation method in solar greenhouse. The results showed that (1) the treatments except for ammonium bicarbonate treatment (AB) significantly decreased soil EC in 0-20 cm soil layer, but only irrigation without amendments (CK treatment) significantly increased soil EC, NO₃^--N in 20-40 cm soil layer. AB treatment significantly increased NH₄⁺-N in 0-20 cm soil layer and NO₃^--N in 20-40 cm soil layer. And the addition of chicken manure (CM treatment) significantly increased the NH₄⁺-N, pH, organic matter, total nitrogen and available nutrients, and significantly decreased the accumulation of NO₃^--N and EC in 0-20 cm soil layer. (2) CM treatment significantly decreased soil bacterial richness and evenness. However, the relative abundance of plant growth-promoting bacteria (PGPR), Bacillus and Pseudomonas increased significantly. For the fungal community, the diversity and abundance of fungi in different treatments were not significantly different from those of before treating. However, the relative abundance of pathogen-Fusarium in AB, PS and CM treatment decreased significantly. The relative abundance of deneficial Aspergillus of CM treatment significantly increased. (3) Considering soil physical, chemical and microbial properties, chicken manure as an organic carbon source, had more positively effects of disinfestation, not only increased its decomposition, but also easy to get. Meanwhile, the application of chicken manure would be helpful for implementing double reduction of fertilizer and pesticides.

Abstract:The effects of integrated tillage pattern on maize yield, utilization efficiency and direction of nitrogen fertilizer in aeolian sandy soil of northeast China were studied, and the relationships between maize yield and nitrogen utilization efficiency under different tillage patterns were discussed, which would provide scientific basis for rational tillage pattern of maize production in this region. In the aeolian sandy soil region, ¹⁵N labelled micro-plots were set up in conventional tillage (CT), integrated tillage pattern 1 (ITP1) and 2 (ITP2) treatment, and CT was taken as contrast treatment. The effects of ITP1 and ITP2 on maize yield, utilization efficiency and direction of nitrogen fertilizer were studied. The results showed that the maize grain yield significantly increased by 30.10% and 15.53% in ITP1 and ITP2 compared with that of CT, respectively. The nitrogen utilization efficiency of three tillage patterns ranged from 27.10% to 35.46%. The nitrogen use efficiency was 35.46% and 31.40% in ITP1 and ITP2, respectively, which was 30.85% and 15.87% higher than that of CT. Compared with CT, the residual nitrogen of ITP1 increased by 18.67%, and the loss rate decreased by 45.65%. The residual nitrogen of ITP2 was lower than that of ITP1, but higher than that of CT, but the difference was not significant. However, the nitrogen loss rate of ITP2 was 24.36% lower than that of CT and 39.17% higher than ITP1. Both of integrated tillage patterns increased maize yield and nitrogen use efficiency, and decreased nitrogen fertilizer pollution. Thus, IPT1 and IPT2 were potential strategies for increasing maize yield in aeolian sandy soil of northeast China.

Abstract:Application of nitrogen inhibitors is an effective way to improve nitrogen fertilizer use efficiency of rice. The effects of nitrogen inhibitors (urease inhibitor N-butylthiophosphoramide, NBPT and nitrification inhibitor 3,4-dimethylpyrazole phosphate, DMPP) and their combinations on yield, nitrogen efficiency and soil nitrogen were studied by field experiment, aiming to provide scientific basis for formulating scientific nitrogen management and reducing nitrogen loss of paddy field in plain along the Huaihe River. A field experiment (between June 2018 and October 2018) using rice cultivar of "Changnuo" 1 as test materials was conducted in Huaiyuan County, Anhui Province (a typical rice growing area along the Huaihe Plain). Five treatments were set up, which were CK (no nitrogen fertilizer), U (urea only), U+NBPT (urea plus NBPT), U+DMPP (urea plus DMPP) and U+NBPT+DMPP (urea plus combined application of NBPT and DMPP). The results showed that addition of NBPT or DMPP into urea increased the yield, nitrogen absorption and utilization, in which the effect of NBPT was better than that of DMPP, and the combination of NBPT and DMPP showed synergistic effect. Compared with U treatment, the rice yield of U+NBPT, U+DMPP and U+NBPT+DMPP treatments significantly increased by 6.8%, 4.3% and 8.6%, respectively, and plant nitrogen absorption increased by 9.6%, 6.5% and 12.2%, respectively, and the difference between the treatments were significant (P<0.05). Furthermore, the addition of NBPT or NBPT+DMPP in urea both significantly improved the nitrogen recovery efficiency (NRE), nitrogen agronomic efficiency (NAE), nitrogen uptake efficiency (NUP) and nitrogen partial productivity (NPFP) (P<0.05). However, urea combined with DMPP also increased in varying degrees, but the difference did not reach a significant level (P>0.05). In addition, the addition of DMPP or NBPT+DMPP in urea both significantly enhanced soil NH₄⁺-N content and microbial biomass nitrogen (SMBN), while reduced soil NO₃^--N content at maturity, and increased the ratio of NH₄⁺-N to NO₃^--N. However, adding NPBT only had no obvious effect. In summary, adding urease inhibitor NBPT or nitrification inhibitor DMPP into urea could effectively improve rice yield and nitrogen use efficiency in plain along the Huaihe River, and the effect of urea added with combination of NPBT and DMPP was the best.

Abstract:The field randomized block experiment method was used to apply fertilizer to alfalfa fields in saline-alkali reclamation areas of the Yellow River Delta, in order to obtain the effects of fertilizer types on alfalfa yield and the changes of soil nutrients, and provide scientific basis for the restoration and delaying recession of alfalfa fields in the Yellow River Delta, and this research had important ecological significance for maintaining the functions of alfalfa fields and the surrounding environment in the Yellow River Delta. The results showed that the application of different types of fertilizers could significantly improve the alfalfa yield, with an average increase of 19%. For different types of fertilizers, the quick-acting fertilizer could get better biological yield of alfalfa in a short period. However, for the annual production, controlled release fertilizer I (AF) and controlled release fertilizer Ⅱ (BF) could promote the increase of branch number, root length, volume and dry weight, while controlled-release fertilizer Ⅱ (BF) was the best in improving the alfalfa yield, it improved the yield by 22% compared with the CK, and there was a significant difference in the yield between controlled release fertilizer I (AF) and quick-acting fertilizer (HF) (P<0.05). The different type fertilizer had different effects on soil nutrient characteristics, the content of soil available potassium and available phosphorus in 0-20 cm depth of fertilizer treatment plots was 1.5~3.0 times higher than that of CK, and this was also the material basis for the increase of total alfalfa yield in the fertilization area, which indicated that reasonable fertilization measures could promote the increase of alfalfa yield and the change of soil nutrients in the Yellow River Delta area, and the increase of forage yield laid a foundation for grassland restoration and delaying recession.

Abstract:With the excellent performance of fertilizer synergist, polyaspartic acid (PASP) may have an effect on the physiological metabolism and nitrogen use efficiency of flue-cured tobacco, which will solve the problems of excessive nitrogen application and low nitrogen use efficiency in tobacco-planting, and provide some reference to the application of PASP in tobacco production. A pot experiment which took the flue-cured tobacco called ‘Yun 87’, and yellow soil, the typical soil of Guizhou Province, was carried out to explore the effects of PASP on the physiological characteristics of tobacco and the fate of nitrogen fertilizer when reducing nitrogen application by ¹⁵N-isotope tracer technique. The results indicated that the reduction of nitrogen fertilizer (30%).and the addition of PASP could effectively improve the utilization rate of nitrogen fertilizer, the improvement effect of N reducing was particularly obvious in the late growth stage of flue-cured tobacco, and PASP application could further enhance the improvement effect. With 30% reduction of nitrogen fertilizer application, the root physiology and leaf photosynthetic characteristics of flue-cured tobacco were significantly affected. Under the same conditions, adding PASP significantly promoted root physiology, leaf physiological morphology and nitrogen use efficiency of flue-cured tobacco. The low level PASP(100 mg/pant)didn't showed significant promotion effect on photosynthetic characteristics of flue-cured tobacco roots and leaves, even though it improved nitrogen utilization rate to some extent. Conversely, the high-level PASP (400 mg/pant)were more conducive to the physiological metabolism of roots and leaves of flue-cured tobacco and increased fertilizer use efficiency. In addition, the result of correlation analysis indicated that there was a significant positive correlation between PASP addition and nitrogen use efficiency (p<0.01).Furthermore, the application of PASP significantly increased the total recovery of nitrogen fertilizer, and for tobacco plant, the ¹⁵N distribution of aerial part was higher than that of underground part in all treatments during the late growth stage, both of them became higher with the increase of PASP. In conclusion, the application of PASP facilitated the physiological metabolism of flue-cured tobacco, N absorption, and minimize nitrogen loss, especially in the treatment of N reduced by 30% + PASP 400 mg/plant.

Abstract:A field experiment was conducted to investigate the effects of organic fertilizer replacing nitrogen of chemical fertilizer on transporting characteristics of soil carbon/nitrogen and wheat yield. The treatments included controlled release urea (CRU), organic fertilizer (OF) replacing 30%, 50% and 70% nitrogen dosage of controlled release urea, with the common urea (Urea) as the control. The results showed that the total biomass of organic fertilizer treatments were significantly increased by 13.83%~17.57%, the grain yield increased by 1.6%~10.5% compared with Urea. With the increase of replacing proportions of organic fertilizer, the increase effect on yield was reduced, and no significant difference was observed between 70%OF and Urea, but they were still significantly lower than the CRU treatment. The agronomic use efficiencies of CRU, 30%OF and 50%OF were significantly improved by 90.2%~124.4% compared with Urea. But there was no significant difference between 70%OF and Urea. The nitrogen partial productivity among organic fertilizer treatments and CRU showed no significant difference. With the increase of replacing proportion of organic fertilizer, the soil total carbon contents showed an upward trend, which was higher than CRU and Urea. However, the total nitrogen contents generally showed a downward trend with the increase of organic fertilizer. During the whole growth period, total nitrogen contents increased from sowing to regreening stage and then decreased. The total nitrogen contents of 30%OF were higher than those in other nitrogen fertilization treatments from grouting stage to maturity stage. With the increase of soil depth, the contents of nitrate nitrogen and ammonium nitrogen decreased. With the increased proportion of organic fertilizer, the nitrate nitrogen contents decreased, but ammonium nitrogen increased in each layer of soil (especially in the regreening period). Inorganic nitrogen contents in soil showed a declining trend during the whole growth period. However, compared with Urea, the nitrate nitrogen treated with organic fertilizer was mainly concentrated in the 0-40 cm soil layer, and the contents of ammonium nitrogen in 0-100 cm soil was higher than Urea and CRU (except seedling stage). Therefore, the application of 30%~50% organic fertilizer replacing nitrogen of chemical fertilizer, combined with controlled release urea, could significantly increase the contents of soil total carbon and ammonium nitrogen, reduce the nitrate nitrogen leaching in 60-100 cm soil, and improve the nitrogen use efficiency and grain yield of wheat.

Abstract:Due to the disconnection between scientific fertilization guidance and the agricultural production, excessive application of phosphorus fertilizer is widespread, which results in the accumulation of large amounts of phosphorus in soil. Accurate evaluation of phosphorus availability in soil is the basis for scientific management of soil phosphorus. Diffusive gradients in thin films technology (DGT) can more accurately reflect the bioavailability of elements in soils than traditional methods. In this study, 60 representative soil samples from the Loess Plateau were used to evaluate the status of soil phosphorus pool and its availability in the Loess Plateau under the condition of imbalanced fertilizer input for long period, and traditional Olsen and the DGT methods were used. The relationships between DGT-P, and Total-P and Olsen-P were also studied. Path Coefficient Analysis was used to explore the relationship between soil phosphorus availability and relevant soil physical and chemical indicators. The results showed that the distribution of soil phosphorus was uneven in the Loess Plateau. Phosphorus deficiency and phosphorus enrichment coexisted, specifically, phosphorus rich samples were mainly from farmland. Soil samples with phosphorus activation coefficient (PAC) less than 2.0% accounted for 76.67% of the total samples, and most soil samples had low phosphorus availability. Because phosphorus input in farmland was too high, activating the unavailable phosphorus in soil was the main target of scientific management of phosphorus in the Loess Plateau. Soil DGT-P was significantly correlated with total-P and Olsen-P (P<0.01). Clay content had the greatest direct effect on soil phosphorus availability compared with other factors, and its effect on Olsen-PAC was positive, and the effect on DGT-PAC was negative. The higher the soil clay content, the larger the available phosphorus pool in soil, but the less available phosphorus could be taken up by plants.

Abstract:The effects of biochar on physiological characteristics of cucumber seedlings in DBP contaminated soil were studied through simulation experiments. Four biochar treatments (CK, C 0.5%, C 1% and C 2%) and three DBP concentration gradients (0,20 and 40 mg/kg) were designed. The results showed that when the biochar was applied to DBP contaminated soil, the stability of cell membrane was enhanced at low concentration (C 0.5%), and remained basically the same as that of CK at high concentration (C 1% and C 2%). The application of biochar significantly enhanced SOD activity in cucumber seedlings, reduced CAT activity and content of photosynthetic pigment (chlorophyll a, chlorophyll b, chlorophyll a+b and carotenoid), but had no regular effect on APX activity, and C 2% treatment significantly increased POD activity. C 0.5% treatment significantly decreased Fsub>0, F_m and F_v/F_m. Φ_PSⅡ decreased at low concentration (C 0.5%), and remained basically the same as that of CK at high concentration (C 1% and C 2%). When the biochar was 0.5% (C 5%) and DBP was 0 mg/kg, q_P was the largest. The effect of applying biochar on NPQ was the most significant in C 1%. Grey correlation analysis showed that the effects of biochar and DBP on cucumber seedlings were firstly reflected in the activities of main antioxidant enzyme, then the chlorophyll fluorescence system changed accordingly, and finally the stability of cell membrane and the change of photosynthetic pigments content were affected. The results could provide scientific basis for further research on biological characteristics of facility crops, DBP pollution control and reasonable application of biochar.

Abstract:A field experiment was carried out to study the effects of controlled-release nitrogen fertilizer (CRNF) application on rice yield, nitrogen use efficiency and leaching loss in Ningxia, to provide technical basis for the application of CRNF in the Yellow River irrigation area. Using Ningjing No.50 rice variety as the research object, with no nitrogen fertilizer (CK) as control, according to the local farmers conventional nitrogen application rate (FP), four controlled release nitrogen fertilizer reduction treatments were set up:CRNF 135 kg/hm² (C-135), CRNF 180 kg/hm² (C-180), CRNF 225 kg/hm² (C-225) and CRNF 270 kg/hm² (C -270). The rice yield, nitrogen uptake and use efficiency, and the concentration of leachate at different soil depth and different rice growth stages were measured. Results showed that the rice grain yields under C-180 and C-225 treatments were not reduced under the reduced nitrogen fertilizer application by 25% and 40%, respectively. That was because the effective panicle number and kernel number of rice were increased. Compared with FP treatment, the nitrogen use efficiencies of CRNF were significantly increased when the nitrogen application rates were below 270 kg/hm², which were 10.22%, 11.10%, and 12.75% higher than FP under C-135, C-180 and C-225 treatments, respectively. The concentrations of total nitrogen (TN) in the surface water and the leachate at different soil depth during the growth period of rice under CRNF were lower than those of FP, and delayed the peak time of TN concentration in the surface water, which reduced the nitrogen loss caused by rice field drainage and runoff. The total nitrogen leaching loss during the whole growth period of FP was 24.57 kg/hm², and the corresponding valueswere between 11.54 kg/hm² to 17.35 kg/hm² under CRNF treatments. The total nitrogen leaching loss was reduced by 46.17% and 49.40% under C-180 and C-225 treatments compared with FP. Considering rice yield and nitrogen loss, the reasonable CRNF application rate in Ningxia is between 180 kg/hm² to 225 kg/hm².

Abstract:In order to explore the dynamic changes of soil hydrothermal environment and spring maize growth under different planting patterns in semi-humid and drought-prone areas of the Loess Plateau, field positioning experiments were carried out in Huating Agricultural Technology Promotion Center of Gansu from 2017 to 2018, and six planting patterns were set up, which were flat seedbed with film mulching (WM), flat seedbed with half film mulching (HM), ridge-furrow with polyethylene film and straw mulching (MRM), ridge-furrow with full film mulching (WRF), ridge-furrow with straw mulching (SM) and flat seedbed without mulching (CK), and the water and heat status of soil profiles in different fertility period of spring maize, crop growth characteristics, crop yield and components during harvest period were measured and analyzed. The results showed that the regulation of mulching planting pattern on soil temperature was mainly manifested in the seedling stage. The film mulching treatment had a warming effect compared with CK. During the whole growth period, the average soil temperature increased by 1.44~2.62℃, while the SM showed a cooling effect, with an average temperature lowering of 0.51℃. MRM, WRF, HM and SM had significant effect on moisture conservation during the whole growth period of spring maize. While, WM was not conducive to precipitation collection, it only had the effect of moisture conservation at the early stage of spring maize growth, with the increasing of crop water consumption at the middle and later stages, the soil moisture content was lower than CK. Compared with CK, the mulching method could increase the yield and water use efficiency of spring maize, among them, the WRF and MRM had the most significant effect. The yield and water use efficiency of WRF and MRM increased by 32.96% and 17.12%, 33.45% and 18.66%, respectively. SM showed a reduction in yield, which was 11.84% and 9.93% lower than CK. Considering the soil hydrothermal environment, spring maize growth characteristics, yield, water use efficiency and other indicators, the ridge-furrow with polyethylene film and straw mulching was the best planting pattern in the semi-humid and drought-prone areas of the Loess Plateau. This study could provide a theoretical basis for rational selection of cover farming measures in the semi-humid and drought-prone areas of the Loess Plateau, and had important significance for the sustainability of farmland.

Abstract:The effects of planting model on the water use efficiency and yield composition of summer maize under irrigated land conditions were discussed in order to provide a basis for high and stable yield cultivation of summer maize. Denghai 685 was used as the experimental material, the effects of different planting densities (6.00×10⁴, 6.75×10⁴, 7.50×10⁴ plants/hm²) on the growth and development, yield, nutrient absorption and water utilization rate of summer maize under wide ridge and furrow planting and equal row spacing horizontal planting models were studied. The results showed that the furrow planting increased the plant height and reduced the stem diameter and dry matter weight per plant. For the summer maize of furrow planting mode, the panicle traits were better than that of planar planting, single panicle weight increased, and was less affected by planting density, showing obvious edge row advantage. The relative chlorophyll content of maize leaves in furrow planting mode was always higher than that in planar planting mode, and the growth period was extended, which provided material guarantee for the later grain formation. When the planting density was 7.50×10⁴ plants/hm², summer maize yield in furrow planting mode was the highest. In the furrow planting mode, the irrigation water amount of summer maize decreased by 52.9% compared with planter planting, the irrigation time decreased by 50.1%, the average daily evaporation reduced, and the water content was higher than that of the planter planting. As a result, the utilization efficiency of irrigation water increased by 139.5% and the average water utilization efficiency increased by 16.7%. Wide ridge and furrow planting was a water-saving planting mode for increasing yield and efficiency of summer maize, which could significantly improve water use efficiency of maize.

Abstract:Wheat-peanuts double cropping system is an important way to solve the contradiction between grain and oil competition and achieve both self-sufficiency. Seeding peanut directly after wheat harvest is the main cultivation method of wheat-peanuts double cropping system. In this experiment, two treatment factors of straw return and tillage were designed after wheat harvesting, and six treatments were conducted rotary tillage with straw remove (RT), rotary tillage with straw return (RTS), no-tillage with straw remove (NT), no-tillage with straw mulch (NTS), deep tillage with straw remove (DT) and deep tillage with straw return (DTS). The effects of straw return and tillage on soil physical and chemical properties and peanut yield were studied. The results showed that different tillage methods had different effects on soil physical and chemical properties. In 0-10 cm soil layer, no-tillage increased the mass ratio of large-size aggregates compared with deep tillage and rotary tillage, improved the stability of aggregates and increased the number of bacteria, fungi, actinomycetes. The deep tillage mainly improved the soil physical and chemical properties of the soil layers of 10-20 and 20-30 cm. Deep tillage increased dry matter accumulation, increased peanut pod yield and seed kernel yield. Under the same tillage, compared with the straw remove, the straw return reduced the soil bulk density, increased soil porosity and the mass ratio of coarse aggregates. Soil organic carbon and total nitrogen contents were increased, and the aggregates stability and the number of soil bacteria, fungi, actinomycetes were improved. The straw return increased dry matter accumulation, and consequently increased peanut pod yield and seed kernel yield. Compared with DT treatment, DTS treated pod yield and seed kernel yield increased by 10.89% and 14.65% respectively. Compared with RT treatment, RTS pod yield and seed kernel yield increased by 10.00% and 11.77% respectively. Compared with NT treatment, NTS pod yield and seed kernel yield increased by 16.31% and 19.82% respectively. Compared with the other treatments, DTS not only improved soil physical and chemical properties, but also increased peanut pod yield and seed kernel yield.

Abstract:The effects of different organic substitution reducing fertilizer patterns on maize (Zea Mays L.) growth and soil fertility were studied,which provided economic and feasible fertilization scheme and theoretical basis for reducing fertilization and increasing benefits in maize production. Five treatments were set up in the field experiments, which were no fertilizer (CK), conventional fertilization (CF), humic acid organic fertilizer + reduction of 10% nitrogen fertilizer + phosphate and potassium fertilizer (HF), fertilizer synergist + reduction of 10% nitrogen fertilizer + phosphate and potassium fertilizer (BN), commercial organic fertilizer + reduction of 10% nitrogen fertilizer + phosphate and potassium fertilizer (OF).The results showed that compared with CF, HF, BN and OF promoted maize growth, increased plant height and stem diameter at different growth stages. Meanwhile, HF, BN and OF effectively improved maize ear traits and yield components,maize yield increased by 11.12%,6.47% and 14.43%,respectively,net income per hectare increased by 217.24 yuan, 564.99 yuan and -506.46 yuan. The above three treatments increased the contents of soil alkaline nitrogen (AN),available phosphorus (AP) and available potassium (AK) in the growth period of maize,and increased fertilizer recovery efficiency (RE), partial factor productivity (PFP) and agronomic use efficiency (AUE). Among them,the recovery efficiency of nitrogen fertilizer significantly increased by 8.15%, 9.34% and 14.08% (P<0.05),respectively, and potassium fertilizer significantly increased by 15.92%, 21.13% and 29.36% (P<0.05),respectively. Therefore,HF and BN treatments could promote maize growth,increase yield and efficiency, improve fertilizer use efficiency and soil fertility, and provide economical and feasible fertilization scheme and theoretical basis for reducing fertilization and increasing benefits in maize production.

Abstract:The content of available nitrogen (N) is generally low in coal mining subsidence reclamation soil. Appling organic and inorganic combined fertilizers can improve soil N fertility, whereas N availability is unclear after fertilization, especially in a new coal mining reclaimed soil. This experiment was conducted in coal subsidence reclamation soil of Shuiyu Coal Mining, which located in Xiaoyi City, Shanxi Province. The experiment included eight treatments which were three organic-inorganic combined treatments (application rate of chicken manure and chemical fertilizer was 1:1, and N at 100, 150 and 200 kg/hm², expressed with MF100, MF150 and MF200), four single application of different amounts of chemical fertilizer nitrogen (N at 0, 100, 150 and 200 kg/hm², expressed with IF0, IF100, IF150 and IF200), as well as control (no fertilization, CK). We evaluated corn yield, aboveground nitrogen uptake, nitrogen use efficiency and mineral nitrogen content in soil profile after crop harvest, so that the suitable fertilization treatment and optimum nitrogen application rate were determined, which could provide scientific theoretical basis for reclaiming mining area soil in a way of high-yield and high-efficiency fertilization. The results showed that:(1) Under the condition of 150 kg/hm² nitrogen fertilizer, the grain yield of MF150 was 12.45% higher than that of IF150 (P<0.05). Furthermore, there was no significant difference in grain yield among IF150, IF200 and MF200. (2) Nitrogen uptake of corn aboveground increased with the increasing of nitrogen application rate, while at the same nitrogen rate, the combined application treatment significantly increased nitrogen uptake by 39.45%~41.46% relative to single chemical fertilizer treatment (P<0.05). (3) At the same nitrogen rate, combined fertilizer treatment could significantly improve nitrogen recovery rate compared with single chemical fertilizer application. The partial productivity of nitrogen fertilizer in differentfertilization patterns showed a downward trend with the increasing of nitrogen application rate. The highest nitrogen agronomic efficiency (24.08 kg/kg) was observed in the IF100 treatment, and there was no significant difference between MF150 and IF100. However, at the same nitrogen rate, agronomic nitrogen efficiency of MF150 significantly increased by 49.56% compared with IF150. (4) After harvesting, mineral nitrogen content in 0-40 cm soil profile increased with soil depth, whereas at the same nitrogen rate there was no significant difference among different treatments. At 40-60 cm depth, the residual mineral nitrogen content of single chemical fertilizer application increased by about 18% compared with the combined fertilizer treatment. In a word, MF150 not only improved grain yield, nitrogen uptake and nitrogen use efficiency, but also reduced residual mineral nitrogen content in soil profile after plant harvest, hence MF150 could be used as a recommended fertilization treatment for this coal mining subsidence reclaimed soil or low-yield farmland similar to the soil type in this experiment.

Abstract:In order to clarify the effects of acid rain on soil organic carbon content and soil carbon pool in paddy fields, the paddy field in Fuzhou Plain was taken as the research object, and the control (CK), simulated pH 2.5, pH 3.5, pH 4.5 acid rain treatments were set up in early and late rice at different growth stages to determine and analyze organic carbon component content of Paddy soil under the simulated acid rain. The results showed that acid rain had different effects on soil total organic carbon (SOC). During the whole growing season of early rice, the effect of acid rain on soil SOC content was not significant (P>0.05). For the late rice, the soil SOC contents of the acid rain treatments were 24.70%, 10.47% and 9.97% higher than that of CK during the greening period, and during the maturity period, the soil SOC contents were 6.33%, 8.75% and 9.46% higher than that of CK. Acid rain significantly increased soil SOC content (P<0.05). During maturation period of early rice, the dissolved organic carbon (DOC) content of the CK was significantly higher than that of the pH 3.5 acid rain treatment. The comprehensive effect of acid rain on soil DOC content was not significant during the whole growth period of late rice (P>0.05). The application of acid rain made the soil oxidizable carbon (EOC) content lower than that of the CK (P<0.05). The soil microbial biomass carbon (MBC) content of early and late rice showed obvious change with time. The MBC content of the early rice in the CK was lower than those in the acid rain treatments (P<0.05), while that of the late rice was the opposite. There was a significant positive correlation between soil SOC and TN, TP, conductivity and water content in early rice (P<0.01). There was a significant positive correlation between soil SOC and TP in late rice (P<0.01). Taking the CK of the early and late rice as the reference soil, the carbon storage activity (A) and carbon storage activity index (AI) of the early rice during greening period and late rice during jointing and mature periods in the acid rain treatment were lower than those of the CK, and there was no significant difference at other growth stages, and within a certain range, the paddy soil organic carbon pool maintained a certain degree of activity. The carbon pool index (CPI) and carbon pool management index (CPMI) of the early rice during greening period, late rice during jointing and mature periods in the acid rain treatments were significantly lower than those of the CK (P<0.05). Acid rain treatment reduced the CPMI, which would be detrimental to rice growth.

Abstract:Aimed to study the effect of intercropping on soil organic carbon storage and its nitrogen regulation effect, soil samples were collected from a 5-year field plot located experiment with maize monoculture, potato monoculture and maize and potato intercropping under different nitrogen application levels. Soil aggregates were graded by dry sieve method, and organic carbon content of aggregate in each size fraction was determined. The results showed that more than 92% of soil organic carbon was reserved in soil macro-aggregates (>2 mm) and small aggregates (2~0.25 mm). Intercropping increased the mass proportion of soil macro-aggregates (>2 mm) and small aggregates (2~0.25 mm), but the effect of intercropping on organic carbon contents of soil aggregates was related to nitrogen application. Compared with the two monocultures, intercropping under low nitrogen (N1) and conventional nitrogen (N2) application increased total organic carbon reserves of soil, but did not significantly affect or reduce the organic carbon reserves under no nitrogen (N0) and high nitrogen (N3) application. Among them, intercropping produced the strongest intercropping carbon sequestration advantage at low nitrogen (N1) by increasing the mass proportion of soil macro-aggregates (>2 mm) and their organic carbon contents, where the total organic carbon reserves of soil were 24.8% and 5.7% higher than those of maize monoculture and potato monoculture respectively. Therefore, proper application rates of nitrogen fertilizer could give full play to intercropping effect and effectively increase soil organic carbon reserves.

Abstract:In order to explore the effects of different irrigation modes on the improvement of severe saline soil in Hetao Irrigation District, this experiment set up three treatments of straw deep burial (SL), gypsum + organic fertilizer (SF) and control (CK), and the distribution characteristics of soil salinity in the 0-70 cm profile of the soil were studied. The results showed that under different irrigation patterns, SL and SF effectively reduced soil pH in 0-15 cm soil layer, the pH decreased continuously with the extension of the treatment time and the increasing of improvement depth. Compared with CK, the pH of SL and SF under drip irrigation decreased by 0.35 and 0.49, respectively, and that of SL and SF under yellow river irrigation decreased by 0.42 and 1.33, respectively, while irrigation mode had little effect on 30-70 cm soil layer. The alkalinity of SF decreased by 43% in the second year and that of SL decreased by 40%, drip irrigation was beneficial to the reduction of alkalinity. In terms of inhibiting salt accumulation, SL and SF could effectively inhibit the aggregation of salt in 0-15 cm soil layer. Compared with CK, the salt of SL and SF under yellow river irrigation decreased by 13.60% and 7.70%, respectively, and that under drip irrigation decreased by 31.60% and 6.90%, respectively. SL had significant salt inhibition effect. The soil salt-based ions showed that the SL and SF significantly reduced the contents of Na⁺ and HCO₃^- in 0-15 cm soil layer under different irrigation modes, the reduction ratio of drip irrigation was higher than that of yellow river irrigation, and the effect was more obvious with the extension of the improvement time. While there was no significant change in 15-70 cm soil layer. The application of gypsum and organic fertilizer increased the contents of SO₄^2-, Ca²⁺ and Cl^-in 0-70 cm soil layer. Through comparative analysis, for the treatment of severe saline soil in Hetao Irrigation Area, both deep burying and gypsum + organic fertilizer could effectively inhibit salt accumulation in severe saline soil, reduce pH and alkalinity. Overall, the improvement effect of gypsum+ organic fertilizer under drip irrigation mode was better than the deep straw burial.

Abstract:In order to evaluate the improvement effect of different amendments on salinized soil, this study took sunflower as the research object. A field split plot experiment was conducted with 4 treatments:the biochar (DC, 22.5 t/hm²),desulfurization gypsum (DS, 37.5 t/hm²),desulfurization gypsum and organic fertilizer (DSF, 37.5 t/hm²) and the control (DCK). The results showed that the soil bulk density were reduced, and soil porosity was increased by adding amendments, among which the biochar gave the best effect. For the plough layer (0-20 cm), the soil bulk density was decreased by 6.11% after harvest, which was 4 times of the control. Soil porosity was increased by 12.89%, which was 5 times of the control. The desulfurization gypsum had the best effect in reducing soil pH value and electrical conductivity, with the biggest drop of 10.09% and 28.51%, respectively. Different amendments had different effects on soil fertility. Compared with the control, the biochar treatment significantly increased the contents of organic matter, available nitrogen and available phosphorus in surface soil after harvest. The desulfurization gypsum significantly increased the contents of available potassium. The sunflower plant height, stem diameter, dry matter accumulation and 100-grain weight were significantly increased by the different amendments. The highest sunflower yield was observed under the biochar treatment, which was 4 539.60 kg/hm², 32.28% higher than the control. In summary, the soil properties were significantly improved after adding different amendments in the salinized soil of Hetao Irrigation District, leading to the increased sunflower growth and yield. The application of biochar with 22.5 t/hm² had the best effect on the improvement of saline soil, followed by desulfurization gypsum of 37.5 t/hm², both of which could effectively improve soil fertility and sunflower yield.

Abstract:As an important biological component in arid and semi-arid regions, biological soil crusts (BSCs) have an important influence on biogeochemical cycle in the ecological process of the region. The effects of biological crust on soil properties under two soil types (loess soil and aeolian sand soil) and three vegetation communities (Stipa bungeana, Artemisia ordosica and Populus simonii communities, farmland as the control) were studied. The results showed that:(1) There was a significant difference among soil physical and chemical properties between BSC layer and 0-10 cm layer (p<0.05). (2) There was no significant difference in soil properties under the three plant community habitats. (3) Soil properties, such as C, N, C/N, Mg, Mn, δ¹³C and δ¹⁵N, and so on, showed the significant differences in the 0-10 cm soil layer under the three plant community habitats, but there no significant difference in soil properties under aeolian sand soil between A. ordosica community and P. simonii community, which indicated that the difference of soil properties in the 0-10 cm soil layer among sampling sites was mainly affected by the characteristics of the soil type itself. (4) The spatial ordering and variations between BSC layer and 0-10 cm layer samples under different vegetation community and soil type habitats were obvious, indicating that the differences in soil properties were dependent on the comprehensive effect of multiple factors in the habitat. Soil type, vegetation and biological crust were important factors for the prediction of spatial heterogeneity of surface soil in this region.

Abstract:In order to study the effect of phosphorus solubilizing fungal flora on phosphorus availability in soil, firstly, the combined effects of three different kinds of phosphorus solubilizing fungi (1 strain belonged to Mortierella Z1, 1 strain belonged to Penicillium Z2 and 1 strain belonged to Aspergillus niger Z3) were studied in the laboratory, and then the best strain combination Z1+Z2+Z3 was determined, and Z1, Z2 and Z3 flora were selected as test strains in the experiment. Then, the potted rapeseed experiment was conducted to study the effect of phosphorus solubilizing fungi combined with insoluble phosphorus (tricalcium phosphate and phosphate rock powder) on phosphorus availability in soil. The results showed that the contents of soil available phosphorus, organic matter, alkaline phosphatase, invertase and rapeseed yield of phosphorus solublilizing fungi treatment significantly increased by 60.00%, 20.21%, 56.45%, 53.81% and 14.38%, respectively, compared with substrate treatment. The above indicators of the treatment of phosphorus solubilizing fungi combined with insoluble phosphorus were higher than those of single application of phosphorus solubilizing fungi. There was no difference in the soil maximum phosphorus uptake between phosphorus solubilizing fungi treatment and substrate treatment. Phosphorus solubilizing fungi combined with insoluble soluble phosphorus could significantly reduce the soil maximum phosphorus uptake. The maximum phosphorus uptake of phosphorus solubilizing fungi + tricalcium phosphate treatment and phosphorus solubilizing fungi + phosphate rock powder treatment significantly decreased by 158.7 and 47.6 mg/kg compared with phosphorus solubilizing fungi treatment. Soil adsorption constants of the phosphorus solubilizing fungi were lower than those of corresponding substrate treatments. Phosphorus solubilizing fungi could reduce phosphorus adsorption by soil. The results showed that the phosphorus solubilizing fungi should be combined with insoluble phosphorus, which had a positive effect on improving soil phosphorus availability.

Abstract:A field experiment was conducted to study the soil water-salt distribution and cotton growth using magnetized water for mulched drip irrigation. Results showed that magnetized water used in the experiment could improve the soil water retention and holding capacity effectively, and promote the water absorption of cotton roots. The soil moisture content of 3 000 Gs magnetized water irrigation treatment was highest at the soil layer of 0-100 cm. The magnetized water irrigation could reduce the soil salt content effectively, due to the magnetized water treatment could facilitate the soil salt leaching from the main root area of cotton into the below. At the 0-100 cm soil layer, the salt contents under magnetized water irrigation treatments were 3 000 Gs(low) < 4 000 Gs < 1 000 Gs < 5 000 Gs < 0 Gs. The soil desalination rates under mulched drip irrigation with magnetized fresh water were 2.7%~28.2%, among which the 3000Gs treatment had the most significate impact on reducing soil salinity. The soil desalination rates for magnetized brackish water treatments were 21.7%~33.9%. The magnetized water irrigation could improve the cotton biomass and output. The yields of seed cotton of magnetized water were increased by 8.98%~31.40% compared with ordinary water. The 3 000 Gs treatment was the best magnetic treatment by taking into consideration of both cotton output and water use efficiency.

Abstract:In order to understand the effect of short-term vegetation restoration on soil physicochemical and microbial community structure, two plants (Medicago sativa L. and Bromus inermis Leyss) were reseeded in the wasteland of Yanqing County, Bejing, and the abandoned land was the CK. Soil bacterial community structures of the V3-V4 16S rDNA gene region and fungi community structures of ITS1-ITS2 were examined by high-throughput sequencing technologies. The results showed that:(1) The soil total nitrogen contents of two vegetation restoration modes were significantly higher than that of CK, and the soil total phosphorus content of reseeded bromegrass was the highest. (2) In the short term, the soil physical properties were significantly improved by the two vegetation restoration modes, and the soil bulk density was significantly lower than that of CK. (3) The soil microbial community structure was affected by two vegetation restoration modes in a short period of time. The relative abundance of ascomycetes in fungi and cyanobacteria in bacteria increased and the biodiversity of fungi and bacteria decreased under two vegetation restorations. (4) Correlation analysis showed that there was a significant positive correlation between soil organic matter contents and the number of ascomycetes, cyanobacteria, and proteobacteria. The two vegetation restoration modes improved the soil physical and chemical properties, and promoted the amount and activity of microorganisms that fixed nitrogen and degraded organic matter.

Abstract:In order to screen out the passivator combination of organic and inorganic materials, which could effectively inhibit the absorption and accumulation of chromium (Cr) and copper (Cu) in various parts of rice, a pot experiment in paddy soil was conducted to study the effects of 15 combinations of passivators on occurrence forms of Cr and Cu in soil and absorption and accumulation of Cr and Cu in rice. The results showed that combined application of 15 kinds of passivators increased the soil pH, soil cation exchange capacity (CEC) and soil organic matter by 0.25~1.04, 2.65%~50.96% and 0.22%~17.20%, respectively, and reduced the exchangeable Cr content by 35.21%~55.63%. Except for the combination of quicklime (L) + passivator 4 (D4) + chicken manure (M) which could significantly increase the soil reducible Cr, other combinations had no significant effect on soil reducible Cr. After application of passivator, soil oxidizable Cr and residual Cr had no significant change, content of exchangeable Cu decreased by 6.66~33.42% in the soil. soil reduciblu Cu and Oxidizable Cu had nosigificant change. The combination of 15 kinds of passivators increased the soil residual Cu content by 0.32%~5.04%, and the combinations of D3, L+D1+M and L+D4+M could significantly increase the content of soil residual fraction. Root system showed the highest enrichment capacity for Cr and Cu. After application of passivator, the contents of Cr in rice roots, straw, rice husk and brown rice decreased by 4.59%~49.41%, 39.84%~76.87%, 7.14%~36.10% and 17.32~67.10%, respectively. After application of passivator, the contents of Cu in rice roots, straw, rice husk and brown rice decreased by 10.57%~48.41%, 7.99%~52.53%, 21.12%~45.11% and 14.39%~66.92%, respectively. The combinations of 15 kinds of passivator could reduce the content of Cr and Cu in brown rice, and the combination of L+D2+M was the best.

Abstract:A pot experiment was carried out to study the effects of applying phytol to lead(Pb)-contaminated soil on soil enzyme activity and Pb availability, and the alleviation effects of phytol to the Pb-contaminated soil under different treatment time were discussed. The results showed that adding phytol to soil in a short time promoted the activities of soil catalase, sucrase and alkaline phosphatase, while inhibited soil urease activity. Moreover, each enzyme had different sensitivity to phytol, among which alkaline phosphatase was the most sensitive. With the prolongation of treatment time, the activities of catalase and urease as well as available Pb content in the soil decreased, while the activities of invertase and phosphatase increased significantly. When the Pb concentration was 600 mg/kg in soil and the phytol concentration was 50 mg/kg, sucrase activity was the strongest, which was 122.28% higher than that of the blank control. Additionally, when the phytol concentration was 250 mg/kg in the soil, the activity of phosphatase was the strongest, which was 251.61% of the blank control. In conclusion, the addition of phytol to Pb-contaminated soil could change soil enzyme activity and reduce the content of available Pb in the soil. What's more, with the prolongation of culture time, the alleviation effect of phytol on Pb-contaminated soil reduced gradually.

Abstract:To provide the theoretical and technical references for rational irrigation of rice in cadmium (Cd) polluted rice area, effects of intermittent irrigation at different growth stages on yield component and Cd accumulation of double-cropping rice were studied by pot experiment. The results showed that:(1) The total yield of double-cropping rice in the treatment of flooded irrigation in whole growth duration (FWD) was the highest, and that of treatment of intermittent irrigation in whole growth duration (IWD) and intermittent irrigation at full heading to mid-filling stage (IHM) followed, and that of treatment of intermittent irrigation at booting to full heading stage (IBH) decreased significantly. FWD was beneficial to increase the seed setting rate, while IWD and treatment of intermittent irrigation at tillering to booting stage (ITB) was beneficial to increase effective panicles number. (2) Irrigation modes significantly affected the Cd content in all rice organs at maturity stage, in which IWD had a significant improvement effect, while FWD had a decrease effect. Cd content in grains of early and late rice treated with IBH and IHM was significantly lower than that of treatment of intermittent irrigation at others stages. (3) As for the Cd accumulation of aboveground of rice in the whole growth duration, FWD was the lowest, and IWD was the highest. In all treatments of intermittent irrigation, Cd accumulation in aboveground of rice was relatively lower in treatments of IBH and IHM. In conclusion, in order to ensure the yield of double-cropping rice and reduce the Cd content in rice grains, FWD was the best irrigation mode in Cd polluted rice area, while IHM was the optimal irrigation mode under condition of water resource shortage.