Abstract:Within an orchard containing 12-year-old late-maturing peach trees (cultivar “Hujing”) in Taihu Lake Basin, China, different fertilizer application rates and management practices were applied to explore the technological approaches to coordinate the high quality and high yield of peach during 2012—2013. The effects of these treatments on soil nitrogen loss by surface runoff in the typical peach orchard were investigated under natural rainfall conditions. In T1 (conventional fertilization practice), total nitrogen concentration (TN)in the surface runoff water reached the peak value of 87.72 mg/L, and TN showed a decreasing trend with the peach growth period. Compared with T1, T2 (reducing fertilization practice to 70% of conventional) and T3 (Inter-planting white clover (Trifolium repens L.)) significantly reduced the average TN in whole peach growth period, which decresed by 26.16% and 12.89%, respectively. In T1, the quantity and coefficient of TN losses by surface runoff reached up to 52.06 kg/hm2 and 6.21%, respectively; these mainly occurred from the peach fruit setting stage to the peach fruit ripening stage, and the strong typhoon season after peach fruit harvest. Compared with T1, T3 significantly reduced the quantity and coefficient of TN losses by 7.41% and 7.41%, respectively. T2 significantly reduced the quantity of TN losses by 26.96%, but TN loss coefficient slightly increased by 3.99%. However, compared with T1, T3 and T2 significantly reduced the partial coefficient of TN losses by surface runoff by 9.51% and 20.70%, respectively.

Abstract:Runoff and sediment yield process on sand-covered loess slopes under simulated runoff conditions were studied through simulating wind-water complex erosion based on the controlled scouring experiments. This study set up three water flow rates (5, 10, and 15 L/min) and five sand-covered thicknesses (0, 5, 15, 25 and 35 mm).The results showed that the runoff yield time on the sand-covered slope was extended, and it extended with the increasing of sand-covered thickness. Under different water flow rate, the runoff yield time on sand-covered slopes (5, 15, 25, 35 mm) were 1.29～1.46 times, 1.66～2.5 times, 2.5～3.76 times and 3.76～4.72 times, respectively, than those on the loss slope. Compared to the loess slope, sediment yield contribution rate was greater than runoff contribution rate on the sand-covered slope. Under the same water flow rate, the total amount of runoff on sand-covered slope was 1.05～1.8 times of that on the loess slope, and the total amount of sediment yield was 1.6～7.5 times. Under different water flow rates, the increase-rate of runoff rate on the sand-covered slope was significantly higher than that on the loess slope within 0～5 min, and in the later 25 min of runoff, increase-rates of runoff rate on both two kinds of slopes were basically coincident. In the whole runoff, the fluctuation of runoff rate on sand-covered slope was significantly higher than that on loess slope. With the increasing of water flow rate, the initial sediment yield strength on sand-covered slope significantly increased. However, in the same water flow rate, the initial sediment yield strength did not increased significantly with the increasing of sand-covered thickness. Under different water flow rates and different sand-covered thicknesses, the sediment yield strength firstly increased dramatically, then decreased, and then gradually reached a steady state, and the fluctuation of sediment yield strength on the sand-covered slope was significantly higher than that on the loess slope. The results indicated that the sand-covered slope destroyed the stability of the water flow, and aggravated soil erosion at a certain extent.

Abstract:In order to research the impact of rainfall intensity on slope erosion process and distribution of sediment particles in the rocky mountain area of North China, two typical soils from this area were selected, and the variation of runoff, the composition of particles and the enrichment rate of particles in erosion sediment were analyzed under 4 different rainfall intensities (30, 60, 90, and 120 mm/h) through rainfall simulation experiments in laboratory. The results were as follows: (1) With the rainfall intensity increased from 30 mm/h to 120 mm/h, the time producing runoff decreased by 79% and 85% for the loess cinnamon soil and calcic cinnamon soil, respectively; (2) Under the 60, 90, and 120 mm/h rainfall intensity, runoff intensity and sediment concentration of the loess cinnamon soil decreased first and then increased with rainfall time extending, and then tended to be stable, while runoff intensity and sediment concentration of calcic cinnamon soil appeared similar trend only under 120 mm/h rainfall intensity; (3) When the rainfall intensity increased from 30 mm/h to 120 mm/h, the content of coarse particle increased in the lost sediment for the loess cinnamon soil, and the contents of sand and coarse silt increased by 67% and 16%, respectively. However, there was no obviously change for the calcic cinnamon soil; (4) In the initial stage of rainfall, the clay and fine silt enriched obviously, and the coarse silt and sand were not easy to be lost, while with the extending of rainfall the enrichment rate of different sediment particles gradually approached to 1, especially under heavy rain.

Abstract:Through the simulated rainfall experiment, the effects of slope and antecedent soil water content on the process of rainfall runoff and sediment on bare land and alfalfa land of coarse texture soil were investigated. The experiment treatment included three slopes（5°, 15° and 25°）and three antecedent soil water content（low, middle and high）. The results showed that the processes of runoff on bare land and alfalfa land were at first increased and then leveled-off under different slopes and antecedent soil water content, and the effects of slopes on runoff volume were marginal. Sediment losses were greatly increased with the increasing slopes, which were increased firstly and then tended to be stable, and also greater changes occurred in bare land. Both of the runoff volume and the mean infiltration were significantly affected by antecedent soil water content. Under the same slope gradient, when antecedent soil water content increased from low to middle, and from low to high, the runoff volume of bare land increased 38.2%—52.8%, and 39.7%—42.8%, respectively, while the runoff volume of alfalfa land increased 27.3%—77.8% and 45.5%—91.1%, respectively. Slopes had significant influences on sediment losses and sediment concentration. Under the same antecedent soil water content, when slope increased from 5° to 15°, and from 15° to 25°, the sediment losses of bare land increased 96.3%—268.7%, and 6.9%—40.3%, respectively, whereas the corresponding values of alfalfa land increased 81.1%—384.2%, and 61.7%—169.9%, respectively. The results showed runoff volume and sediment losses of alfalfa land were significantly lower than bare land at same slope and antecedent soil water content. The findings indicate that antecedent soil water content and slope of coarse texture soil play important roles on the process and amount of soil erosion. The vegetation not only reduces runoff by canopy interception, but also decreases antecedent soil water content through consuming soil moisture.

Abstract:In this study, the soil erosion process and erosion amount were simulated by KINEROS2 model according to the artificial simulation test of the runoff plots with different slope length (1，5，10，15，20 m) under different rainfall intensity (25，50，75 mm/h). The effects of different slope length, rainfall intensity and their interactions on soil erosion process and erosion amount were analyzed contrastively, and the simulation results and applicability of the KINEROS2 model were also evaluated. The results showed that the slope length was linear with the total runoff（R2＞0.990）, and a power function relationship existed between slope length and total erosion amount（R2＞0.900）. The total runoff and total amount of erosion increased in multiples as rainfall intensity increased, and the increasing rate in total amount of erosion was 2～3 times higher than that of total runoff. There was an interaction between slope length and rainfall intensity, which showed a positive effect on slope runoff and erosion process. The effects of slope length and the interactions of rainfall intensity-slope length on slope erosion amount were more obvious than that of rainfall intensity. The simulation of runoff process and total erosion amount based on KINEROS2 model were better than that of erosion process and total runoff, respectively, indicating that the KINEROS2 model was more suitable for the simulation of runoff process and total erosion amount. Generally, the KINEROS2 model had a better simulation effect on slope soil erosion process and erosion amount of runoff plot, which showed that KINEROS2 model had good applicability in plots scale in arid and semi-arid areas, northwest China.

Abstract:Under the background of the “Grain for Green” program to control severe soil loss from human activities, the soil erosion and sediment yield were estimated based on the sediment delivery distributed model (SEDD) and the revised universal soil loss equation (RUSLE) in the upper reaches of the Beiluo River on China’s Loess Plateau. The model was used to simulated the spatial vatiations of soil erosion intensity and sediment yield in 1990, 2000 and 2010. The results show that the average soil erosion modulus were 18 189.72 t/(km2·a)，7 408.93 t/(km2·a) and 2 857.76 t/(km2·a), respectively, and the average annual sediment yield were 14 093.31 t/(km2·a), 5 997.65 t/(km2·a) and 2 394.37 t/(km2·a), respectively in 1990, 2000 and 2010. Besides, the average soil erosion modulus gradually decreased with the increasing vegetation coverage. The results also showed that both the soil erosion modulus and sediment yield were the highest in the altitude of 1 475～1 575 m. The average soil erosion modulus gradually increased with the increasing slope gradient, and with 75% of soil erosion was ascribed to the region with slope ＞15°. Moreover, the ranking of the average soil erosion modulus from high to low was: sunny slope＞half-sunny slope＞half-shady slope＞shady slope. This results provide an useful reference for the rational utilization of water and soil?resources and offer a technical basis for using RUSLE to estimate the soil erosion on the Loess Plateau of China.

Abstract:This study selected daily precipitation data of 57 main meteorological stations from 1956 to 2013 in Fujian province to calculate rainfall erosivity by applying the daily rainfall erosivity model and analyze the impact of ENSO events on rainfall erosivity in Fujian province. The results indicated that although the impacts of ENSO on meteorological stations were different in different areas, there were some general rules as follows: (1) The trend of rainfall erosivity showed general upward but an evident inter-annual and intra-annual variation; (2) Rainfall erosoivity was significantly related to SST anomaly in equatorial Pacific. The rainfall erosivty during El Ni?o period was relatively higher than that during the La Ni?a period, but they were both lower than the average rainfall erosivty in Fujian province; (3) There were extremely significant correlation between rainfall erosivity and SOI and MEI. Through analyzing the effect of ENSO on rainfall erosivity, it would provide reference and basis for soil erosion prediction of and soil conservation in Fujian province.

Abstract:In order to identify the influencing factors of wind erosion in black soil area of Northeast China, the wind erosion rates of black soil under different wind speeds (5～14 m/s), soil water contents (2%～11%), and straw coverage rates(0～80%) were measured through a series simulated wind experiments. Subsequently, the relationships between the wind erosion rate of black soil and the factors were quantitatively analyzed. The results showed that the black soil began to be eroded when the wind speed was slightly greater than 5 m/s, and wind erosion rate of black soil increased exponentially with increasing wind speed. The wind erosion rate under 14 m/s of wind speed (at 2% of soil water content) was 11.6～42.7 times higher than that under 8 m/s of wind speed. Moreover, the wind erosion rate of black soil increased with the increasing of soil water content when the soil water content was less than 5%, while it decreased with the increasing of soil water content when the soil water content was between 5% and 11%. Especially, the wind erosion rate of black soil was close to zero when the soil water content exceeded 11%. In addition, the wind erosion rate of black soil was significantly reduced by straw cover and an exponential relationship was found between them. For instance, the wind erosion rate of black soil with 20% of straw coverage (at 2% of soil water content) was 72.6%～92.3% lower than that of bare land. However, wind erosion rate was only decreased by 0.02～1.20 g/(m2·s) when the straw coverage increased from 20% to 80% (at 2% of soil water content). In conclusion, wind erosion rate of black soil was significantly affected by wind speed, soil water content, and straw coverage in Northeast of China in this study, and their importance in decreasing wind erosion listed in the order of wind speed＞soil water content＞straw coverage.

Abstract:In order to reveal the effect of chemical measures on prevent tillage erosion of sloping fields in purple soil, the impacts of polyacrylamide (PAM) on soil structural stability and tillage translocation were studied in the plots with five slope degrees as 5°, 10°, 15°, 20° and 25° using magnetic tracer and stimulated tillage experiments. The results indicated that： (1) Mean translocation distances of plots added PAM were significantly lower than that of CK (without PAM application) , and the tillage translocation significantly decreased by 49.16 % and 67.96% on 20° and 25° slope plots, respectively; (2) Compared with CK, the content of non water stable aggregate that less than 0.25 mm declined by 33.74%, 46.67%, 37.56%, 52.70%, and 62.50% on the 10°, 15°, 20°, and 25° slope plots added PAM, respectively. In the plots added PAM, the percentage of mean aggregate destruction (PAD) decreased by 60.05%, while mean weight diameter (MWD) and mean geometric diameter (MGD) increased by 41.94% and 55.09%, respectively, compared with CK; (3) Tillage translocation was positively linear correlated with PAD, while was negatively correlated with MWD and MGD (P＜0.05). These results suggested that the application of PAM could effectively reduce tillage translocation, enhance soil structure stability, and reduce soil erosion. PAM can be used to control tillage erosion on the steep slope (over 20°).

Abstract:From the point view of retarding runoff, slowing down slope, improving soil physicochemical properties, increasing soil enzyme and microbial activities, biodiversity conservation, etc, this paper summarized the research progress in the mechanisms of soil erosion control of hedgerows. Soil and water conservation benefits and influences of farmland slope and balanced fertilization on different hedgerows in the hilly region of Southwest China were explored. In this region, researches mainly tended to be focused on herbs like Vetiveria zizanioides and Hemerocallis citrina and trees like Leucaena leucocephala, of which Hemerocallis citrina was usually occurred with fruit trees. Finally, soil biological characteristics and distance of hedgerows were put forward, which could give a reference for further research, and provide the theoretical bases for the improvement of the efficiency of fertilizer.

Abstract:In order to investigate the influence of infiltration water quality on soil hydraulic characteristics, two types of water (distilled and tap water) were selected to carry out in four pressure heads (0, -3, -6, -9 cm) on yellow loam and red loam by using a disc infiltrometer. The results showed that infiltration rate, hydraulic conductivity and sorptivety increased with the increase of the water electrical conductivity, and the soil sorptivety in red loam differed significantly under different conductivity of water (P<0.05). Under the low head pressure, the soil hydraulic conductivity was significantly different between two types of water (P<0.05). By contract, the difference of soil hydraulic conductivity between two types of water was not significant under high head pressure. The influence of water quality on (fine pore) soil hydraulic conductivity was mainly under the low pressure head. The contribution of macropores and medium porosity in the yellow and red loam soils to water flow increased with the increase of the conductivity of water. However, the contribution of the small pores to the flow decreased with the increase of the conductivity of water. Different types of water had significant influence on the contribution rate of different grades of porosity to water flow in red loam (P <0.05). Study of the influence of water quality on soil hydraulic characteristics was beneficial for discussing the influence of water quality on the experimental results, correctly understanding the soil hydrological processes, developing and utilizing low quality water resources, and improving irrigation quality and irrigation efficiency.

Abstract:An adjacent field was taken as a reference and soil infiltration rates of layered soil bunds (the upper, the central and the lower) were determined using double rings on the purple-soil sloping farmland. The results showed that: (1) The infiltration processes of all layered soil bunds and the field dropped steeply then decreased slowly till stable. However, there were differences on the duration to the stable infiltration. It cost a relatively longer time (110 minutes) for the upper bund to the stable state. The time for upper one was 9%, 82%, and 18% longer than that of central bund, the lower bund and the field. In perspective of infiltration performance, the soil permeability was sequenced as the initial infiltration rate, the mean infiltration rate, and then the steady infiltration rate. In view of layered soil bunds, the mean infiltration rate and the 120 minutes cumulative infiltration was sorted as the upper bund, the central bund, the field, and the lower bund. The initial infiltration rate was sequenced as the central bund, the upper bund, the field, and the lower bund, while the steady infiltration rate was sorted as the field, the central bund, the upper bund, and the lower bund. (2) Four models had been used to simulate the soil bund infiltrations. Among them, the general experience model was considered as the optimum one, and it was followed by the Kostiakov model, the Horton model and the Philip model. (3) The permeability of soil bunds had close relation with soil physical properties. The initial infiltration rate was significantly negative related to the initial water content and soil bulk density (P＜0.05). The mean infiltration rate and the 120 minutes cumulative infiltration was significantly negative correlated with the silty particles volume and the initial water content (P＜0.05), and significantly positive correlated with the sandy particles volume and the total porosity (P＜0.05). The results of this study can provide a foundation for bunds construction as to control soil erosion on purple-soil farmlands.

Abstract:Based on the data measured in the Jinghe River Basin (JRB) between 1965 and 2014 (including daily precipitation, runoff and concentration), the spatio-temporall characteristics of hyper-concentrated flow were analyzed. Flows with daily concentration greater than 100 kg/m3 were identified as hyper-concentrated flows. Analysis showed that, the occurrences of hyper-concentrated flows in the JRB can be grouped into three periods, which were 1965—1978, 1979—1990 and 2006—2014. Hyper-concentrated flows occurred frequently before 1978, and the occurrence decreased dramatically after 2006. Moreover, the JRB is divided into two parts, the north and the south part, where the temporal distributions of hyper-concentrated flows had different characteristics. For the north part, the sediment yield modus decreased with the increasing drainage area, while the runoff modus increased with increasing drainage area. For the south part, the modus of the runoff and sediment yield both might increase with the increasing drainage area. The temporal characteristics of hyper-concentrated flow were the same in the south and north part, JRB. So, the complex effect sizes during the first period changed to linear relation gradually. Analysis indicates that hyper-concentrated flows are effectively controlled by water and soil conservation practices in the JRB.

Abstract:Soil water infiltration process of field mulched by different thickness of gravel-sand in northwestern arid area of Ningxia was studied by using one-dimensional vertical water infiltration method. This study selected the gravel-sand thickness as the impact factor, and set five levels of thickness (0, 6, 9, 12, and 15 cm). The variation laws of wetting front movement and infiltration amount were observed, the infiltration characteristics of each treatment were compared, and the infiltration process was simulated using model fitting in this study. The results indicated that gravel-sand mulching improved soil water infiltration capacity, soil wetting front distance and infiltration volume increased significantly. Compared with CK, the cumulative infiltration increased by 4.3%, 11.8%, 12.8% and 17.1% under gravel-sand thickness of 6, 9, 12 and 15 cm, respectively, and average infiltration rate increased by 25.8%, 38.7%, 50% and 62.9%, respectively. Meanwhile, gravel-sand mulching changed the soil water infiltration curve. As the increasing of the gravel-sand thickness, the initial infiltration rate grew rapidly, while the steady infiltration rate increased slowly. Compared with CK, the initial infiltration rate raised by 40%, 81%, 91% and 110% under gravel-sand thickness of 6, 9, 12 and 15 cm, respectively, and the steady infiltration rate increased by 15.3%, 17.9%, 20.5% and 25.6%, respectively. The Kostiakov model, Horton model and Philip model were used to simulate the soil infiltration process, and the results indicated that Horton model fit better (R2＞0.98) than the rest two models, and it was more suitable to analyze and predict the soil infiltration process under different thickness of gravel-sand mulching in the northwestern arid area.

Abstract:The study based on laboratory soil-column experiments to research the effects of different gravel content and particle size on soil infiltration process and the applicability of the traditional soil infiltration model by four models. The results showed that the cumulative infiltration of soil decreased with the increase of gravel content, and the change of the wetting front in soil column was reduced and gradually tend to be level-off with the increase of cumulative infiltration. When the gravel content was less than 20%, the cumulative infiltration rate increased with the increase of the particle size, and there was no difference between the cumulative infiltration and wetting front with time when the gravel content increases to a certain value (20%～30%). There was a good linear relationship between the amount of cumulative infiltration and wetting front distance. Green-Ampt model, General model, Horton model and Kostiakov model were used to fit the relationship between infiltration rate and infiltration duration. Horton model showed best fitting effect when the gravel content was 5%, but worst in 10%～30%, while general model was more applicable, the fitting effect of other models varied with gravel content and particle size.

Abstract:In order to characterize water redistribution and gas-heat diffusion of reconstruction soil filled with gangue in coal mining areas, guide engineering design and rebuild soil ripening technology, a simulator was designed in laboratory. Soil water content, temperature and soil CO2 concentration could be constantly measured by laid sensors and detectors in different depth of soil column. The results showed that soil water infiltration process was slowed down and the water-holding capacity of the upper soil was increased because of good water resistance from coal gangue layer. However, the water content of coal gangue layer was significantly lower, approximately 10%, than that of topsoil due to the poor water-holding capacity of gangue. Coal gangue had higher thermal diffusivity, higher temperature than that of topsoil with heating, could form sustainable temperature gradient and temperature difference with topsoil layer in reconstruction soil. The effects of heated from below on topsoil was small, which it was mainly influenced from indoor temperature in the short run. In addition, the temperature changing curve of topsoil is similar with the temperature of laboratory and its biggest fluctuation range was for 2.89 ℃. The effects of aerating CO2 from column bottom on CO2 concentration of topsoil soil was also very small, because gas transport from coal gangue layers to soil ones would easily be cut off as so to gas accumulated in the soil layer below. The coal gangue could have a negative impact on microbial living environment to adjacent topsoil layers and declined microorganism activities. The effects of coal gangue on topsoil layer were brought down when the cover soil thickness was 60 cm. The influences gradually would be weakened with the thickness increased.

Abstract:In this study, we used hydrogen and oxygen stable isotope tracer technique to determine the water isotopic compositions of precipitation, soil water, groundwater, surface water and xylem water for summer corn during the growing season in 2016 in Yucheng, Shandong Province. Both direct inference approach and multi-source linear mixed models (Iso-Source) were applied to estimate the sources of root water uptake and their contributions in different growing seasons of summer corn. The results showed that the linear model of precipitation was δD=7.80 δ18O +8.61 for Yucheng, and the intercept and slope were less than the values of global precipitation model due to evaporation. Summer corn mainly used shallow groundwater during the seedling stage and the contribution was 89.6% due to the low soil moisture content. During the rainfall-abundant jointing stage, it mainly imbibed water from the 0—10 cm soil layer, and the contribution was 85.8%. During the heading stage, it mainly imbibed water from the 10—60 cm soil layer，and the contribution was 62.9%. The corn mainly used water from deeper soil layer during the filling stage (20—100 cm, 69.7%), because the root was in the deep soil layer and soil water content was stable. During the mature stage, it mainly imbibed water from the more than 60 cm soil layer with the low soil moisture content and the deep root，and the contribution was 96.1%.

Abstract:In order to ascertain the impacts of microorganism (bacillus subtilis) on soil improvement and water movement in saline alkali soil, a laboratory 1D infiltration experiment of brackish water with different concentrations (0 g/L, 1 g/L, 2 g/L, 3 g/L and 4 g/L) was conducted. The results showed that, bacillus subtilis reduced the infiltration capacity of the soil significantly, and slowed down the water flow. Compared with the control, the cumulative infiltration and the final wetting front distance were significantly decreased in soil with bacillus subtilis. The reduction in the cumulative infiltration was up to 40.97% under the brackish water concentration of 2 g/L. The wetting front distance showed the similar results as infiltration. Then, Philip and Kostiakov infiltration model were used, and the fitting result showed that the imbibition rate S of Philip formula was less than that in the corresponding control groups. This suggested the diminished solid water absorbing ability of capillary force might be due to the viscosity property improvement made by bacillus subtilis. The experience coefficient K of Kostiakov formula was smaller than the control, which indicated that the initial infiltration rate of bacillus subtilis contained solid was lower. Nevertheless, the empirical exponential β was greater than the control, demonstrating that the containing solid capacity of bacillus subtilis was fading with the increasing infiltration time. After the infiltration of brackish water, the soil with bacillus subtilis showed a better aggregate structure, which could significantly improve the ventilation and water holding capacity. Soil water characteristic curve showed that, with the same moisture content and concentration, the water suction of the bacillus subtilis containing solid was stronger than the corresponding control, with more reduced matrix potential, which indicated that bacillus subtilis increase the water holding capacity and inhibit the water evaporation and infiltration. Finally, the water characteristic curve was fitted using van Genuchten model. In this formula, the soil residual water content, saturated water content and coefficient associated with intake value increased, and shape coefficient decreased. In conclusion, bacillus subtilis can improve the solid structure effectively and reduce solid infiltration. This study could provide a theoretical support for the microorganism application in soil improvement.

Abstract:In order to illustrate the effect of biochar on soil retention ability in dry farmland, this study measured the soil bulk density, soil porosity, soil moisture constants and the soil water retention curve of the soil with different biochar addition through setting located experiment in typical dry farmland of the Loess Plateau. The results showed that biochar adding reduced soil bulk density, and increased soil porosity. With the increasing of the biochar adding, the reduction range of soil bulk density and the increasing extent of soil porosity were both enhanced. The change of soil structure was the most obvious when the adding amount of biochar reached 50 t/hm2. Soil bulk density of 0—5 cm, 5—10 cm and 10—30 cm soil layers decreased by 7.01%, 9.91% and 16.60% compared with control group, respectively, and soil capillary porosity increased by 19.47%, 21.02% and 29.94% compared with control group, respectively. The biochar adding increased soil saturated soil water content, soil field capacity and soil effective moisture content. With the increasing of the biochar adding, all the soil moisture constants showed rising trends, but the increasing extent decreased when the biochar amount reached 40 t/hm2. This study suggests that the addition of biochar improved the water retention ability of dry farmland, but the retention ability of soil tended to be stable when the adding amount of biochar reached 40 t/hm2.

Abstract:To explore the water and nitrogen transport characteristics under water and fertilizer integration of bubbled-root irrigation, through the indoor fertilizer infiltration test, the migration characteristics of wetting front migration, soil moisture, ammonium nitrogen and nitrate nitrogen were studied under different soil initial water content (4.13%, 7.21%, 11.06%, 14.01%). The relationships between the cumulative infiltration amount, the wetting front migration distance and the soil initial water content of bubbled-root irrigation were established. An empirical model was proposed to calculate the cumulative infiltration volume and the wetting front migration distance under different initial water content. Results showed that: the cumulative infiltration, the wetting front migration distance, the moisture in the body, the distribution and transformation of nitrogen were all affected by the initial water content of soil. At the same time, the cumulative infiltration reduced with the increase of initial soil water content, while the wetting front migration distance increased with the increase of initial soil water content. The higher the initial water content of soil was, the larger volume of wetting body was, and the wilder water, ammonium nitrogen and nitrate nitrogen distributed. The closer to the emitter outlet, the contents of ammonium nitrogen and nitrate nitrogen in the soil were higher. The infiltration coefficient K decreased with the increase of initial soil water content, while the infiltration index α showed an opposite trend. The fitting parameters a and b of horizontal wetting front both increased with the increase of initial soil water content. The vertical downward wetting front migration index c increased with the increase of initial soil water content, while the infiltration index d decreased with the increase of initial soil water content. With the continuous redistribution of soil moisture distribution, the moisture distribution in the moist body was more uniform, and the uniformity of water distribution evaluated by Christiansen uniformity coefficient Cu, in moist body was 61.99%, 74.27% and 83.60%, respectively, at the end of irrigation, redistribution of 1 day and 3 days. With the redistribution, the content of ammonium in the wetted body gradually decreased, but the distribution region of ammonium nitrogen was almost unchanged. With the redistribution, the distribution of nitrate nitrogen in the wetted area became larger, the average value of it increased, and the maximum value of it had a downward trend. The above research results can lay the foundation for further researches on water and nitrogen use efficient of bubbled-root irrigation technology.

Abstract:To confirm the effects of mulching on soil aggregate characteristics, the distribution of micro-aggregate and macro-aggregate and also stoichiometry of macro-aggregate were explored. In the 20—40 cm soil layer mulched with manure, the percentage of the 10～150 μm micro-aggregate was 84.5%, which was 3.7% higher than control, while the percentages of the 1～5 mm macro-aggregate and the ＞5 mm macro-aggregate were 47.74% and 33.04%, respectively, and the corresponding changes were 56.8% and 49.5% compared with control. In the 0—20 cm soil layer, total N, total P, TOC of all soil aggregates mulched with manure were, on average, 1.04, 0.81, and 14.39 g/kg, respectively, which were 2.9, 5.1, 1.4 times that measured in control, and the corresponding values under treatment with wood chips were 0.61, 0.32, and 7.42 g/kg, respectively, which were 1.7,1.0, 2.3 times that measured in control. The C/N, C/P, N/P ranges of soil aggregate mulched with manure were 8.29～22.65, 4.45～27.18, and 0.44～1.89, respectively, and the ranges of that of wood chips were 4.09～29.60, 5.32～59.88, and 1.04～3.29, respectively, while the control were 4.71～12.24, 10.08～25.42, and 0.86～3.10, respectively. In all, mulching promotes the percentage of the 1～5 mm macro-aggregate, and weaken the ＞5 mm macro-aggregate and micro-aggregate. Moreover, the total N, P, TOC and C/N, C/P of the soil aggregates were all increased in degree with muchling.

Abstract:Based on the sampling (0-10, 10-20, 20-30 and 30-40 cm) and lab analysis of two representative natural secondary oak forest plots in Liaodong mountain area, which was located in the town of Benxi City River Estuary and the fairy town of Zhuanghe City, the distribution characteristics of soil organic carbon, total nitrogen ,and total phosphorus at the depth of 0-40 cm was studied, and the relationship between organic carbon and other physical and chemical properties was discussed. Results showed that soil organic carbon, total nitrogen, total phosphorus, total potassium, available nitrogen, available phosphorus, available potassium and cation exchange capacity tended to decline with the increasing soil depth, however soil bulk density generally increased with increasing soil depth. According to the t test and variance analysis, there was a significant difference between the experiment indicators and the soil layer (P<0.05). Moreover, the content of silt showed a very high positive correlation with the soil organic carbon, pH value, total nitrogen, total phosphorus, total potassium, alkaline hydrolysis nitrogen, available phosphorus, available potassium and cation exchange capacity (r=0.430 9~0.919 0, n=44, P<0.01). While soil bulk density and the content of sand had a significant negative correlation with soil organic carbon (r=0.388 3~0.670 6, n=44, P<0.01). But the content of clay had no significant correlation with soil organic carbon. Stepwise regression analysis showed that the relationship between soil available nitrogen, the ratios of carbon to nitrogen, total potassium, pH, total nitrogen and organic carbon was the closest. Overall, there was close relationships between soil organic carbon and other physical and chemical properties, and the total nitrogen, available nitrogen, the ratios of carbon to nitrogen, total potassium and pH had big impact on it. At the same time, each index had obvious profiles distribution.

Abstract:To understand the characteristics of erosive aggregate loss in tropical and subtropical zones, a combination experiment of two discharge flow (5 L/min and 7.5 L/min) and four simulated rainfall intensities (0 mm/h, 60 mm/h, 90 mm/h, 120 mm/h) was conducted. The variation characteristics of aggregates, such as mean weight diameter (MWD), geometric mean diameter (GMD), fractal dimension (D), mean weight soil specific area (MWSSA), were analyzed. The results showed that: the aggregates of ＜0.05 mm occupied 19％～58％ of the total sediment during the early phase of the event, and the tendency declined first then stabilized with rainfall duration. The content of ＞0.25 mm aggregates in erosive sediment was highest, and the tendency increased first and stabilized later, with the rainfall duration,. When the discharge flow increased from 5 L/min to 7.5 L/min under the same rainfall intensity, MWD and GMD of aggregates increased, while D and MWSSA decreased. MWD and GMD of aggregates in the sediments without rainfall were lower than that in the rainfall; however, D and MWSSA of aggregates in the sediments without rainfall were higher than those with rainfall. Under the condition of the same rainfall, MWD and GMD increased as rainfall intensity increased, while D and MWSSA decreased.

Abstract:Adopting field investigation and indoor analysis, the changes of soil water-stable aggregates distribution and the driving forces in the conversion of paddy field to tea garden were examined. The results showed that soil water-stable aggregate in the paddy field and tea garden was different among different size class and soil layer. With the decrease of the particle size, the water-stable aggregate firstly decreased and then increased in paddy soil and tea plantation with 5 years, 10 years. In the 15 years tea garden, water-stable aggregate was increased with the decrease of the particle size. With the increasing years of tea planation, water-stable aggregate was given priority to ＞2 mm turn into ＜0.25 mm both in 0—20 cm and 20—40 cm soil layer, while ＜0.25 mm water-stable aggregate was the predominant contributor in 40—60 cm soil layer. The water stability of soil aggregate decreased with the increasing years both in 0—20 cm and 20—40 cm soil layer, whereas the ranking from high to low in 40—60 cm soil layer was: tea plantation 5 years＞tea plantation 10 years＞paddy field＞tea plantation 15 years. The stability water of soil aggregate was positively correlated with the content of ＞0.25 mm water-stable aggregate. The water stability of soil aggregates was positively correlated with the soil chemical properties, and the main driving factors were ＞0.25 mm aggregates, soil bulk density and total porosity. In terms of nutrients, the driving forces of water stability in paddy field, tea garden 5 years, 10 years and 15 years were organic matter, organic matter and CEC, organic matter, CEC and effective phosphorus content, content of CEC, respectively.

Abstract:In order to determine the effect of organic fertilizer application on the calcium distribution and aggregate in cultivated brown soil, the field cultivated brown soil fertilized for nearly 30 years was taken as study object. The soil aggregate was classified by dry sieve method, while the effect of single and combined application of organic fertilizer on the distribution of different calcium forms was analyzed. The results showed that the single application of organic fertilizer could increase ＞1 mm graded aggregate content compared with control, the increment increased with the amount of organic fertilizer and could reach 66.68%. Combined nitrogen and phosphorus fertilizer application reduced ＞1 mm graded aggregate content compared with the single application of organic fertilizer. The single application and combined nitrogen and phosphorus fertilizer application decreased 0.25～1 mm graded aggregate content compared with control, while the highest decrease was 15.20%. The single application and combined nitrogen and phosphorus fertilizer application increased total calcium content in soil. The calcium content of the single application of organic fertilizer was higher than that of combined nitrogen and phosphorus fertilizer application. The highest increment of calcium (11.67%) was the treatment received higher organic fertilizer application. The highest total calcium content was in the ＞1 mm graded aggregate of the treatment received single organic fertilizer, while the highest total calcium content was in the 0.053～0.25 mm graded aggregate of treatment received combined nitrogen and phosphorus fertilizer. The single organic fertilizer and combined nitrogen and phosphorus fertilizer application increased water-soluble calcium content in each graded aggregate. The single application of organic fertilizer improved exchangeable calcium content in soil, while the trend was reversed when combined nitrogen and phosphorus fertilizer was applied. The single application of organic fertilizer and combined nitrogen and phosphorus fertilizer all increased acid soluble calcium content in soil. Correlation analysis indicated that the total calcium content in each aggregate grade was the key factor effects the distribution of the various forms of calcitonin. Therefore, long-term organic fertilizer application not only increased the larger grade aggregate content in soil, but also enhanced the calcium content in larger aggregate.

Abstract:To explore organic carbon distribution characteristics in different soil aggregates of Wutai Mountain vertical zone, the soil samples which including subalpine meadow soil, mountain meadow soil, brown soil, leached cinnamon soil, and calcareous cinnamon soil from high altitude to low altitude were collected in August 2016. Water-stable aggregates in different levels (＞2 mm, 2～0.25 mm, 0.25～0.053 mm and ＜0.053 mm) of different type soils were harvested through wet-sieving method and physical fractionation technique, and the TOC, POC, and MOC of all level aggregates and soils were further analyzed. The results showed that subalpine meadow soil, mountain meadow soil, and brown soil all mainly composed by ＞2 mm aggregates, which accounted for 45.13% of all water-stable aggregates. However, cinnamon soil and calcareous cinnamon soil were mainly composed by 2～0.25 mm and 0.25～0.053 mm aggregates respectively, reached 33.79% and 39.95%. With the decrease of altitude, soil organic carbon content decreased. Besides, the organic carbon content of ＞2 mm and 2～0.25 mm aggregates in different type soils had a great significant positive correlation with the corresponding soil organic carbon content and the correlation coefficients were r＞2 mm=0.986, r2～0.25 mm=0.966 (P＜0.01). Although with the decrease of soil aggregates diameter, the POC contents of sub alpine meadow soil, mountain meadow soil, and brown soil decreased, and the POC contents of leached cinnamon soil and calcareous cinnamon soil increased. The MOC content of subalpine meadow soil, mountain meadow soil and brown soil were highest in ＞2 mm aggregates, and the MOC content of leached cinnamon soil, calcareous cinnamon soil were highest in 2～0.25 mm and 0.25～0.053 mm aggregates, respectively. The soil MOC content was significantly greater than the POC content, and these two showed a positive correlation in soils and all level macro-aggregates (P＜0.05). In addition, the content of POC and MOC in soils also showed a positive correlation with the content of soil organic carbon (P＜0.05). Therefore, the soil aggregates turned from macro-aggregates to micro-aggregates with the decrease of altitude, and the carbon capture ability of subalpine meadow soil, mountain meadow soil and brown soil was stronger than leached cinnamon soil and calcareous cinnamon soil.

Abstract:Based on the method of combined determination and light scattering, we studied the effect of organic matter on the surface charge properties of soil colloidal particles and condensation process of colloidal particles in water bodies. The results showed that the addition of organic matter significantly changed the surface charge properties of soils, because of the total charge number increased about 6.8%, the specific surface area decreased about 12.3%, and organic matter addition decreased the surface charge density of the particles and the surface potential. Further theoretical calculations showed that the addition of organic substance reduced the electrostatic repulsion between colloidal particles, which made the net gravity increase and aggregation of soil colloids become easier. The aggregation characteristics of soli colloids in the water bodies were studied by the method of light scattering, the results showed that the critical coagulation concentration (CCC) was 91.6 mmol/L before removing organic matter, and it was 139.3 mmol/L after organic matter was removed, and the difference betweent these two values was significant. The critical surface potentials for colloidal particle dispersive or aggregate were both about -150.0 mV at the corresponding concentrations. And the above concentrations were the critical concentrations that net gravitational attraction appeared between particles. The effect of organic matter on the aggregation characteristics of colloidal particles in water bodies was mainly through changing surface properties and the corresponding interactions of particles.

Abstract:Carbon storage and carbon loss were the serious issues in the soil erosion region of typical steppe. By field investigation and simulated rainfall, effects of grazing intensities on the soil erosion, soil organic carbon storage and carbon loss of typical steppe in Inner Mongolia were studied. The results showed that: (1) The grazing intensity had a great effect on the surface soil organic carbon, and the organic carbon storage increased firstly and then decreased, the ranking was: the light grazing＞the no grazing＞the moderate grazing＞the heavy grazing; the soil organic carbon storage in 0—40 cm soil layer under different grazing intensity changed significantly and showed a vertical decreasing trend. (2) PFTs were most important, followed by N soil, and finally climate the soil erosion was mainly affected by rainfall intensity, followed by slope, and finally grazing intensity. (3) As for the same slope, the rainfall intensity had a greater influence on soil organic carbon loss than the grazing intensity; the soil erosion and soil organic carbon loss increased with the increasing rainfall intensity and grazing intensity. The findings indicate that it is necessary to control grazing intensity for soil erosion for soil erosion in typical steep.

Abstract:To study the variation of soil organic carbon in fractions with the restoration process, we selected the different ages of Pinus massoniana plantations as the research object and take the bare land (CK1) and secondary forest (CK2) as the control, which is basically consistent with the similar management histories in erosive red soil area. The physical and chemical fractionation method was applied, three pools were isolated in soil organic carbon. The active carbon was composed of dissolved organic carbon (DOC) and particulate organic matter (POM); the slow carbon was composed of SOC bound to silt and clay and SOC attached to sand particles or occluded in aggregates; the passive carbon is a chemically recalcitrant fraction. The results showed that, in the process of vegetation restoration (0～30 years), the storage of active carbon and its distribution proportion in vegetation restoration significantly was improved in the recovery of 7～10 year (P＜0.05), its storage and distribution remained at a relatively stable level in the vegetation recovery of 27~30 year; the storage of slow carbon and its distribution was significant changes in the recovery of 27～30 year (P＜0.05). The distribution of active carbon pool was decreased, there was significantly correlated between active carbon pool (POM, DOC) and slow carbon pool (P＜0.01), indicating that the active carbon pool in the recovery gradually transformed to the slow carbon pool after 7～10 year; the stocks of recalcitrant carbon pool continued to increase along with the chronosequences, but its proportion remained relatively stable level. Correlation analysis showed that there was a significant correlation between the chronosequences and the factions with the pools (P＜0.01), at the same time, the slow carbon pool was the most sensitive in the process of vegetation, indicating that the soil organic carbon in activated carbon accumulation gradually transformed into slow carbon pools accumulation in P. massoniana recovery, thereby affecting the recalcitrant carbon accumulation ,which was good for the long-term preservation of soil organic carbon.

Abstract:In order to reveal effect of urbanization on soil organic carbon fractions and carbon pool management index, soil samples collected from six remnant evergreen broad-leaved forests in the Pearl River Delta were analyzed. The six sampling areas included three urban forests (botanical garden, Baiyunshan and Maofengshan) and three suburb ones (Heshan, Conghuashimen and Dinghushan). Soil samples were collected from 0—10 cm and 10—20 cm soil layers, respectively, and total organic carbon (TOC), readily oxidizable organic carbon (ROC) and non-readily oxidizable organic carbon (NROC) of the samples were determined. Results were as follows: (1) TOC content of urban forests soil was significantly lower than that of the suburban forests soil (P＜0.05). (2) In the surface soil (0—10 cm layer), soil carbon pool activity and carbon pool activity index of the urban forests were both significantly higher than those of the suburban forests (P＜0.05), and in the sub-surface soil (10—20 cm layer), the above pattern was also observed but there was no significant difference in both indices between these two kinds of forests (P＞0.05). (3) In both two soil layers, soil carbon pool index and carbon pool management index of suburban forests were both significantly higher than those of urban forests (P＜0.05). This study suggests that urbanization increased soil organic carbon activity of the remnant evergreen broad-leaved forests, but urbanization was detrimental to the accumulation of total organic carbon in soil.

Abstract:In order to study the effects of straw and waste application on the soil aggregates and soil carbon, nitrogen and phosphorus in the riverside jasmine garden in Fuzhou, the distribution and stability of soil aggregates, including ＞0.25 mm soil aggregates (DR0.25), mean weight diameter (MWD), geometric mean diameter (GMD), fractal dimension (D), and the content and stoichiometric ratio of soil carbon, nitrogen and phosphorus of 0—10, 10—20 and 20—30 cm soil layers were examined in the control (C), straw (S), straw+gypsum (SG), straw+biochar (SB), straw+slag (SS) amendments plots. The results showed that 0.053～0.25 and 0.25～2 mm particles were the predominant contributor. Compared with the control, DR0.25, MWD and GMD under the straw treatments decreased by 19.86%, 19.18%, and 37.98%, respectively, whie D increased by 14.26%, and aggregate stability decreased. Compared with the straw amendment plots, in the straw+gypsum, straw+biochar, straw+slag treatments plots, both DR0.25 and MWD varied slightly, and GMD increased by 2.34%, 0.63%, and 12.67%, respectively, whereas, D was reduced by 2.31%, 6.26%, and 5.01% respectively, furthermore, aggregate stability also increased. Compared with control, in the straw, straw+gypsum, straw+biochar, straw+slag treatments plots, carbon, nitrogen and phosphorus content were significantly increased in 0—10 cm soil, , however, those in 10—20 and 20—30 cm soil layers varied slightly, showing the accumulation of nutrients to the surface soil layer. In all, the results indicating that biochar and slag can be taken as the combination amendments with straw returning to improve the effect of straw returning.

Abstract:Soil salinization is an important type of soil degradation, which seriously restricts the development of agricultural production. Weibei region is the second granary of Shaanxi province. However, due to the higher groundwater level and salinity, the region is suffering from soil salinization, big waterlogging disasters, and high soil compaction for a long time. In order to analyze the influences of soil physical properties, such as water-stable aggregate, soil bulk density and soil texture on salt distribution in soil profile, soil samples were collected from typical farmland in Weibei region through 10 km×10 km mesh point method. The results showed that: (1) soil salinization in Weibei region was not very serious but at a high potential risk. The proportion of mild salinized soil accounted for 45.56%, while the moderate salinized soil only 23.01%. (2) Soil salt content increased with the increasing soil depths in the profile, which indicated that the soil salt would be accumulated to the topsoil with water evaporation in improper managements. Strong negative correlation was observed between water-stable aggregate and soil salt content in the studied profiles. While, the correlation between soil bulk density and salt content varied with the degree of soil salinization. The influence of water-stable aggregate on salt content in topsoil was stronger than that of soil bulk density. However, significant correlation occurred between soil texture and salt content only in 0—20 cm soil layer. (3) The effect of soil physical properties on salt content was not only found in the same soil layers but also in different soil layers. Namely, the ectopic impact was found in the influence of soil physical properties on salt content, and this impact was related to the degree of soil salinization. When salt content was lower than 1 g/kg, a power function relationship was observed between soil bulk density in 40—60 cm layer and salt content in 20—40 cm layer. An increasing function was observed between soil bulk density in 20—40 cm layer and salt content in 0—20 cm layer when salt content ranged from 2 g/kg to 4 g/kg. However, when salt content was higher than 2 g/kg, a decreasing function would be found between soil bulk density in 0—20 cm layer and salt content in 20—40 cm layer. A decreasing function was observed between water-stable aggregate and salt content, especially when salt content was higher than 2 g/kg.

Abstract:In order to reveal the physicochemical properties and their influence mechanism of soil in different rocky desertification in karst area, a four-year monitoring was conducted on soil in different rocky desertification degrees (potential, light, moderate, intensity) before, during and after rainy season in rocky desertification area, Bijie, Guizhou. Physicochemical properties and their correlation characteristics of different soils were analyzed. The results were as follows: in the soils with the same rocky desertification degree, the contents of soil organic matter, total phosphorus, available phosphorus, total nitrogen and hydrolysable nitrogen were all in order as: during rainy season＞after rainy season＞before rainy season. With the deterioration of rocky desertification, soil retention ability, capillary retention ability, capillary porosity and total porosity of soil increased, and the contents of total phosphorus, available phosphorus and organic matter in soil decreased. Compared with the soil in potential rocky desertification degree, total nitrogen contents of soils in light rocky desertification, moderate rocky desertification and intensity rocky desertification increased by 5.6%, 20.9% and 26.6%, respectively, and hydrolysable nitrogen contents of different soils increased by 3.5%, 18.3% and 36.2%, respectively, total potassium contents of different soils increased by 15.8%, 30% and 46.3%, respectively, available potassium contents of different soils increased by 3.9%, 11.3% and 16.5%, respectively. Correlation analysis suggested that organic matter content, total phosphorus content, total nitrogen content, bulk density, total porosity and capillary retention ability correlated significantly (p ＜0.05), and organic matter content, total nitrogen content, bulk density and total porosity correlated extreme significantly (p＜0.01). These results can provide theoretical and scientific basis for the comprehensive control of rocky desertification.

Abstract:In order to improve the nitrogen use efficiency and reduce the resource waste and the risk of environmental pollution, a study on the leakage loss of controlled release nitrogen fertilizer (CRNF) application in hilly area of South China was conducted. The effects of CRNF (T3～T6) application on nitrogen dynamics and loss of TN，NO3-—N and NH4+—N in leachate water under different treatments in Spring Maize soil were explored. The results showed that the leakage water was 3 888.40～3 948.69 L when the nitrogen application rate was 168～240 kg N/hm2, hence fertilizer application rate had no significant effect on the leakage volume (P＞0.05). Average leaching loss concentration of TN, NO3-—N and NH4+—N under T3 treatment were as follows 32.66 mg/L, 29.41 mg/L, and 0.26 mg/L. Compared with the application of common urea (T2), T3 treatment with the same amount of nitrogen application rate decreased by 24.99% (P＜0.01), 25.56 % (P＜0.01) and 25.71 % (P＜0.05), respectively. Meanwhile, the loss load decreased by 24.10 %( P＜0.01), 25.62 %( P＜0.01) and 18.97 %(P＞0.05), respectively, and namely 53.07, 47.14 and 0.47 kg N/hm2. When the nitrogen fertilizer application rate was reduced by 10 %, 20%, 30%, the corresponding average TN loss concentration were 28.81, 26.50 and 24.34 mg/L, which decreased by 11.79%（P＞0.05）, 18.86%（P＜0.05）, 25.47%（P＜0.05）compared to T3. Similarly, the loss load were 41.78, 36.62, and 33.90 kg N/hm2, which decreased by 21.27%（P＜0.01）, 31.00%（P＜0.01）, 36.12（P＜0.01）, respectively. NO3--N is the major component of leakage nitrogen loss, which accounted for 88.83%～92.75% of TN loss load, and DON was also not negligible. During the planting of Spring Maize in dry land, the CRNF application rate with 192 kg/hm2 could effectively reduce the loss of nitrogen leaching and the risk of environmental pollution, and even increase yield and efficiency.

Abstract:From April 15 to October 15 in 2015, a field experiment was carried out to explore the appropriate water and fertilizer management mode in the farming area of black soil in Northeast China. In this paper, the effects of mulching, fertilizer amount and fertilization model on water consumption, maize biological characters, water use efficiency (WUE) and partial fertilizer productivity were studied. The experiment consist of two mulching treatments, i.e. mulching (M) and no-mulching (W), 3 fertilization levels with 230 kg N/hm2 (W1), 280 kg N/hm2 (W2) and 330 kg N/hm2 (W3), and 3 fertilization schemes of 60%-40%-0% (F1), 60%-20%-20% (F2), 33%-33%-33% (F3), a total of 20 treatments. Results showed that the film mulching treatments reduced the ineffective evaporation of soil moisture. Plant grew much better with the increase of fertilizer amount, then the demand for soil moisture increased, and the maximum soil moisture consumption treatment was WW3F2. Moreover, the differences of fertilizer amount and fertilization scheme result in different biological characters and plant yield. Soil nutrient use efficiency increased with increasing fertilizer amount under F2 treatment, specifically, plant yield of MW3F2 increased by 2.8% and 12.7% compared with MW3F1 and MW3F3, respectively. Finally, heavy fertilization and water consumption could increase the yield, while decreased WUE and fertilizer partial productivity, and also f MW1F2 and MW3F2 were the priority of planting pattern in black soil area.

Abstract:In order to make full use of natural resources, reduce soil salinization and improve farmland productivity, this experiment took spring wheat sole cropping, maize sole cropping and sunflower sole cropping as control, the effects of spring wheat-sunflower multiple cropping on soil moisture, soil salinity and farmland productivity were investigated in Hetao irrigation district. The results showed that before spring wheat harvest, the soil moisture in 0—100 cm soil layer of spring wheat-sunflower multiple cropping and spring wheat sole cropping were lower than maize sole cropping and sunflower sole cropping. After spring wheat harvest, soil moisture in top layer of spring wheat-sunflower multiple cropping, maize sole cropping and sunflower sole cropping were higher than spring wheat sole cropping, but soil moisture in 20—80 cm soil layer were lower. Soil salinity of different cropping patterns changed drastically before spring wheat harvest, but changed gently after spring wheat harvest. Different cropping patterns had great influence on soil salinity in 0—40 cm soil layer, but had less influence on soil salinity under 40 cm soil layer. When multiple cropping sunflower harvest, top soil salinity of spring wheat-sunflower multiple cropping were lower than that of spring wheat sole cropping, maize sole cropping and sunflower sole cropping, by 32.52%, 16.70% and 24.92% respectively, and 0—100 cm soil layer soil salinity were lower by 13.32%, 8.88% and 12.07% respectively. Equivalent yields of spring wheat-sunflower multiple cropping were 126.01%, 3.86% and 3.21% respectively, higher than that of spring wheat sole cropping, maize sole cropping and sunflower sole cropping.Spring wheat-sunflower multiple cropping could reduce soil salinity, improve farmland productivity, and have a certain development prospect in Hetao irrigation district.

Abstract:Effects of different nitrogen application rates on sweet potato yield and nitrogen use efficiency under different soil fertility conditions were explored. Field experiments were carried out to investigate the effects of nitrogen fertilizer on yield, yield components, dry matter accumulation and nitrogen use efficiency of Yanshu25, under different soil fertility levels. As results showed, without nitrogen fertilizer, the number of branches, the length of the longest stem, the leaf area index, and the yield were following this order: high soil fertility＞middle soil fertility＞low soil fertility, and the differences were significant. Nitrogen fertilizer could increase the first three indices under three soil fertility conditions (p＜0.05), but had no significant effect on the number of the largest internodes. Field plots with high, middle and low fertility levels gained the largest yields when nitrogen fertilizers were 50, 100, and 150 kg/hm2, respectively, which increased by 16.06%, 29.63% and 33.33%,respectively, compared to the control. Besides, nitrogen fertilizer could increase accumulation of above-ground dry matter s of sweet potato under all soil fertility levels. Lastly, with the increasing of nitrogen addition, the nitrogen accumulation were increased for middle and low fertility of plots, but first increased and then decreased for high fertility of plots. With the increasing nitrogen application rates, nitrogen use efficiency decreased under the high fertility, while increased under the low fertility, and was the highest under the middle fertility with 100 kg/hm2. The optimum nitrogen application rates for sweet potato in high, middle and low soil fertility are 50, 100 and 150 kg/hm2, respectively.

Abstract:Effects of the usual controlled-release potassium chloride (CRK1), the high controlled-release potassium chloride (CRK2), the usual mixed potassium chloride with controlled-release potassium chloride (BBF1) and the high mixed potassium chloride with controlled-release potassium chloride (BBF2) on maize yield, potassium use efficiency, and soil available potassium were investigated in a 2-year field experiment using maize-wheat rotation system, and the none potassium (CK), the usual potassium chloride (K1) and the high potassium chloride (K2) were set up as controls. To provide the basis for application of controlled release potassium chloride, studied the synchronous nutrition relationships of between controlled-release fertilizers with maize. The results showed that: (1) The yield of maize under BBF2 treatment in 2014 and 2015 were 11 697.8 kg/hm2 and 11 921.1 kg/hm2, respectively. Compared with K1 treatment in the 2014 and 2015, the yield increased by 13.3% and 15.7%, respectively and the incomes increased 16.6% and 19.6%, respectively. (2) The agronomic potassium use efficiency under BBF2 treatment was greater significantly by 49.0% and 41.9% over those of the K1 treatment in 2014 and 2015, respectively. The physiological potassium use efficiency under BBF2 treatment was greater significantly by 17.6% and 34.8% over those of the K1 treatment in 2014 and 2015, respectively. The highest apparent potassium use efficiency occurred in BBF1 treatments, which were 23.73% and 35.22% in 2014 and 2015, respectively. (3) Plant height and stem diameter were significantly increased with potassium fertilizer application. Maize plant height increased under BBF2 treatment from the later tasseling stage to the mature stage. Both CRK and BBF treatments increased significantly the leaf SPAD values of the late tasseling stage, and significantly improved the absorption of potassium and enhanced grain filling properties. The results indict that the application of the mixed potassium chloride with controlled-release potassium chloride can meet the maize nutrition requirement of different growth period, and improved maize yield and potassium use efficiency, among which, BBF2 treatment is the optimal fertilization scheme.

Abstract:A field experiment was conducted in 2013—2015 at Shouyang in Shanxi Province of China, to study the effects of different mulching modes on the changes of soil moisture and temperature, and to explore the best planting pattern of dryland maize in Shanxi Province. Three different mulching patterns were included, i.e. plastic film-straw overlay (MS) , full plastic film mulching (FM) , narrow plastic film mulching (NM). And soil temperature, moisture, and yield of spring maize were assessed using traditional farming pattern as control (CK). Results showed that the diurnal variation of MS was smaller than that of FM, NM and CK, the difference was 8.8 ℃; and 25～35 d after sowing, the temperature in 15cm soil layer increased from 19.1 ℃ to 26.5 ℃, showing a weak warming effect. During the whole growth period of maize, MS raised 68 mm of soil storage in the 0-160 cm soil layer compared to CK, and the 3-year average water content in MS, FM and NM increased by 4.5%, 0.4% and 1.2% respectively. Compared to CK, maize yield of MS increased by 17.4% , WUE of MS increased by 24.8% . Thus, the plastic film combined with straw mulch could improve soil temperature, moisture, and consequently improve maize yield and WUE, should be the best mulching pattern for dryland maize cultivation in Shanxi Province.

Abstract:The fertilizer nitrogen absorption and utilization, soil nitrogen residue and soil nitrogen pool deficit under different nitrogen levels (0, 50, 100, 150, 200, and 250 kg/hm2) were studied using 15N isotope tracer technique during nutrition transformation period of 5-year-old Fuji Apple. The results showed that with the increasing of nitrogen application, utilization ratio of fertilizer nitrogen decreased gradually, and the percentage of tree nitrogen absorbed from soil nitrogen gradually decreased, but from nitrogen fertilizer increased. After one month of nitrogen application, 5.75%～12.99% of fertilizer nitrogen was absorbed by tree, and 29.62%～39.74% of it remained in 0—60 cm soil, and 47.27%～64.64% of it lost by other means. With the increasing of nitrogen application rate, the amount of fertilizer nitrogen absorbed by tree and soil residual nitrogen increased gradually, but the utilization rate of fertilizer nitrogen and soil residual rate decreased, and meantime, the loss amount and the loss rate of fertilizer nitrogen were both increasing gradually. Residual fertilizer nitrogen in the soil mainly distributed in the topsoil (0—20 cm), and soil 15N abundance increased significantly with the increasing of nitrogen application. With the increasing of nitrogen application, soil total nitrogen balance changed from deficit to surplus, and this indicated that low nitrogen application rate could lead to the decrease of soil nitrogen fertility, and the excessive application of nitrogen could increase the accumulation of nitrogen. There was a significant positive correlation between soil total nitrogen balance and nitrogen application rate, and the regression equation was y=0.3147x–16.144（R2=0.990 2), soil nitrogen pool reached balance when nitrogen application rate was 51.30 kg/hm2.

Abstract:In order to compare the effects of different straw returning rates on soil total organic carbon, microbial biomass carbon, cellulase activity and catalase activity at different soil depths, an in-situ experiment was conducted in a separate mode of planting and returning. The experiment was conducted with four levels of returning amount, i.e. 0% (R0), 0.44% (R1), 0.88% (R2) and 1.32% (R3), and three different returning depths, i.e. 0—15 , 15—30, and 30—45 cm. The result showed that returning for 1 year, soil organic carbon content, microbial biomass carbon content, cellulase activity and catalase activity in 0—15 cm soil layer increased with the increasing amount of straw, and those under R3 treatment had the greatest significantce, which increased by 30.98%, 101.16%, 172.72%, and 5.40%, respectively. In 15-30 cm soil layer, the contents of total organic carbon,microbial biomass carbon and catalase activity in soil treated with straw were higher than those in R0, but there were no significant differences between R1, R2, R3, while cellulase activity increased with the amount of straw returning. In 30—45 cm soil layer, soil organic carbon content, microbial biomass carbon content and cellulase activity of R2 and R3 were significantly higher than those of other treatments, and no significant differences were in catalase activity of all treatment. Compared with returning for 1 year, , the total organic carbon content, soil microbial biomass carbon and cellulase activity during returning for 2 years decreased, with the deree of 8.59%～35.36%, 6.74%～29.16%, and 6.18%～31.72%, but catalase activity increased, the largest increase occured in R3 (with the increase of soil depth, the increase rate of 14.14%, 10.14%, and 12.11%). This study indicates that in the case of separate mode of planting and returning, the high amount of straw can be returned to the field, and also the soil fertility can be improved effectively.

Abstract:This study aimed to analyze the effects of rice straw (rice straw) and its different ingredients (decomposed rice straw, dissolved organic material, non-active ingredient rice straw) on microbial biomass carbon, nitrogen (MBC, MBN) and dissolved organic carbon, nitrogen content (DOC, DON) in the well-drained paddy soil from quaternary red clay. An indoor thermostatic incubation experiment was carried out. The results showed, compared to the control (S treatment), rice straw (RS+S treatment), decomposed rice straw (DRS+S treatment) and non-active ingredient rice straw treatment (NARS+S treatment) increased by 11.17% (p＜0.01), 1.83% and 6.25% (p＜0.05) in MBC, respectively, dissolved organic material treatment decreased by 2.67% in MBC. RS+S treatment increased by 15.29% in MBN, while DRS+S, DOM+S, and NARS+S decreased by 15.19%, 3.09% and 15.92% in MBN, respectively. Compared with S, RS+S, DRS+S, DOM+S and NARS+S treatments significantly increased by 13.33%, 10.88%, 6.81% and 11.41% in DOC, respectively (p＜0.01); RS+S, DRS+S and DOM+S treatments significantly increased by 6.96%,10.84% and 10.12% in DON, respectively (p＜0.05); and NARS+S treatment significantly increased by 13.41% in DON (p＜0.01). Compared with S, DRS+S and NARS+S treatments significantly increased MBC/MBN (p＜0.01), while RS+S treatment significantly decreased the MBC/MBN (p＜0.05), and DOM+S treatment almost had no effect on MBC/MBN. Among the treatments, there were no significant differences in DOC/DON.As for MBC, MBN, DOC and DON in the well-drained paddy soil from quaternary red clay, rice straw and the different ingredients work in the same direction, but in different degree. The findings can provide a basic data for understanding the controls of rice straw and its different ingredients on MBC, MBN, DOC and DON, and a scientific basis for revealing the relationship between the source and conversion of available nutrient in paddy soil, which are useful for improving the use efficiency of Rice Straw and soil fertility.

Abstract:The purpose of this study was to acquire the effect of organic carbon fertilizer on biomass and root morphology, and to determine the optimum amount of organic carbon fertilizer in the arid area afforestation, therefore a pot experiment was conducted to study the effect of 6 levels organic carbon fertilizer on biomass, fertilizer utilization rate, and root morphology of 4 plants (Syringa oblate, Swida alba, Pinus tabuliformis, and Fraxinus chinensis). The results showed that significant differences existed in 4 plants’ root and total biomass among the different fertilizer application levels in the test dosage range. The 4 plants’ total biomass increased by 22.41%~82.94%, 42.22%~112.96%, 10.60%~55.59%, and 9.46%~42.61% compared with the control groups, and the maximum value were at level T4 (20 g/strain), T3 (15 g/strain), T5 (30 g/strain), T5 (30 g/strain). With the increase of organic carbon fertilizer application, the fertilizer utilization efficiency of 4 plants decreased by 0.903 kg/kg, 1.946 kg/kg, 0.037 kg/kg, 0.145 kg/kg. The influence of fertilizer on root morphological characteristics (root length, surface area, average diameter, tips, crossings) of S. oblate and S. alba all reached a significant level. Average root diameters of Pinus tabuliformis and Fraxinus chinensis were less affected by fertilizer application, but the other four characteristics showed significant differences under different amount of fertilizer application. Compared with the control groups, longest root length of 4 plants increased by 41.29%~112.77%, the maximum root surface area increased by 34.73%~154.26%, the maximum average diameter increased by 3.85%~42.62%, the maximum tips increased by 47.41%~70.15%, the maximum crossings increased by 22.93%~109.10%. The results showed that the shrub was more sensitive to fertilizer than the tree, but the tree performed better than the shrub at high level fertilizer utilization. The fertilizer utilization for tree should be higher, 30 g/strain for instance, and for shrub shouldn’t more than 20 g/strain in the arid area afforestation.

Abstract:A field plot experiment was conducted to explore the effects of cross ridge covered with plastic film on soil net nitrogen mineralization in Wulongchi small watershed during maize growing period. Results showed that the soil net nitrogen mineralization contents under cross ridge covered with plastic film were significantly lower than those of non-mulched treatment at the mid-term stage of seedling and the early stage of jointing, and the decreases were 7.8%～57.0% and 2.2%～52.8%, respectively. While at the later stage of jointing, heading stage and maturity stage,, the former were significantly greater than the latter and the increases were 352.9%～703.3%, 52.5%～311.0% and 15.2%～334.8%, respectively. The higher correlations existed between the soil net nitrogen mineralization contents under cross ridge covered with plastic film and the soil moisture, temperature and total nitrogen contents at the seedling stage, jointing stage, heading stage and maturity stage (0.6＜Grey correlation degree≤0.8). The soil net nitrogen mineralization contents under cross ridge covered with plastic film showed a significant linear relationship, with soil temperature at the seedling stage (F=7.205, P=0.023), with soil moisture and temperature at the jointing stage (F=36.861, P=0.001), and with soil moisture at the maturity stage (F=42.438, P=0.007).

Abstract:Ammonia volatilization was a major path of nitrogen losses in Paddy field. In order to evaluate the effects of different nitrogen schemes on ammonia volatilization and nitrogen use efficiency in Jianghuai hilly region, a field experiment by the closed airflow chamber method was conducted. The results showed that the ammonia volatilization loss ratio was the highest at tillering stage, followed by basal stage, and finally heading stage. Compared with the conventional fertilization, the ammonia volatilization loss amount and the ratio under the application of slow-release urea combined with common urea were decreased by 26.23% and 4.52%, respectively, while the nitrogen use efficiency increased by 6.07%. Ammonia volatilization loss was positive correlated with ammonium nitrogen concentration in the surface water. Therefore, the application of slow-release urea combined with common urea can not only reduce ammonia volatilization loss, but also obtain higher economic benefit, which is suitable to be recommended in Jianghuai hilly region.

Abstract:The responses of maize photosynthesis, yield and water use efficiency to different drip irrigation amount at different growth stages under full film mulching were investigated by a field experiment in the Hetao Irrigation District, China. The experiment consisted of 3 treatments, i.e. low (90 mm), medium (135 mm) and high (180 mm) drip irrigation amount with full film mulching, respectively. Except jointing stage, the maize leaf photosynthetic rate, transpiration rate and stomatal conductance under high and medium drip irrigation treatments were significantly higher than those under low drip irrigation (P＜0.05), while no significant differences were observed between high and medium drip irrigation treatments. Leaf water use efficiency (LWUE) under low drip irrigation was significantly higher than that under high drip irrigation (P＜0.05), and under high drip irrigation, LWUE at jointing stage was significantly higher than all other growth stages. The diurnal variations of maize leaf photosynthetic rates, transpiration rates, stomatal conductance and intercellular CO2 concentrations at different growth stages were found under all drip irrigation amounts. Photosynthesis range, peak height and peak time in the diurnal course with high and middle drip irrigation were significantly different from those with low drip irrigation. The survival rates, kernel number, 1000-grain weight and yield of maize with high and medium drip irrigation were significantly higher than those of low drip irrigation treatment (P＜0.05). The difference of high and medium drip irrigation treatments with full film mulching on the maize ear and yield was statistically insignificant, indicating that high drip irrigation amount was not necessary under full film mulching for the maize yield increase in the Hetao Irrigation District. This study could provide a theoretical basis for improving crop photosynthesis under drip irrigation in the Hetao Irrigation District, and thus enhance crop yield and water use efficiency.

Abstract:Aggregate stability, cadmium distribution and transformation in bulk samples, and particle size fractions were studied of brown soil through freeze-thaw cycle method. The freezing conditions were implemented under -10, -20 and -30 ℃, respectively, and the thawing condition was implemented under 10 ℃. Soil aggregate particle size, soil mean mass diameter, grain size fraction cadmium loading, and the cadmium transformations in bulk soil and particle size fractions were measured. The results showed that both the fraction of particles ＞2 mm and soil mean mass diameter increased significantly when soil experiencing freeze-thaw cycles, and the formerranged 38.4%～54.6%.Cadmium mainly accumulated in particles ＞2 mm,and it contributed 51.2%～57.2% of cadmium to the contents in bulk soil. The exchangeable fraction of cadmium and the organically bound fraction of cadmium significantly decreased (P＜0.05), and the Fe and Mn oxide bound fraction of cadmium and the residual fraction of cadmium increased significantly (P＜0.05) in bulk soil and particle size fractions for the soil experiencing freeze-thaw cycles. The results suggest that the bioavailability of cadmium decrease in soil experiencing freeze-thaw cycles.

Abstract:In order to reveal the significance of soil CO2 on cave environment, statistical and regression analysis were conducted on the related data of the cave environmental indexes and the overlying soil properties in 2016. The results showed that the cave air CO2 concentration and soil CO2 concentration presented the significant seasonal variation and obvious hysteresis phenomenon. The difference between summer and winter of cave air CO2 concentration corresponded with soil 2# was 793～884 mg/kg. The highest differences of soil water PCO2 and drip water PCO2 between summer and winter were 1.12 and 0.41 respectively. So the drip water PCO2 and soil water PCO2 also showed obviously seasonal variations. The lag phenomenon was shown among soil CO2, cave air CO2, drip water PCO2 and soil water PCO2, e.g., the coefficients between soil water PCO2 of soil water and drip water were improved from 0.123 without hysteresis to 0.596 with hysteresis. Under the hysteresis, the highest total contribution of soil CO2 concentration to cave air CO2 concentration was 84.6%, higher than that without hysteresis.

Abstract:The effects of vermicompost produced by Eisenia foetida on organic carbon content, soil acidity and Cu/Pb speciation were studied in acid soil contaminated by heavy metals through simulated pot experiment. Vermicompost was made with cattle waste and rice straw, respectively. The results showed that soil total organic carbon content increased by 25%～83% in the soil with 2.5%～10% amount of vermicompost, and the soluble organic carbon of the cattle waste vermicompost was significantly higher than that of the rice straw vermicompost (P＜0.05), and there was no significant difference in other organic carbon content between the two kinds of vermicompost. Vermicompost increased the soil pH (H2O) value by 0.38～1.13 pH units, and reduced exchangeable hydrogen and aluminum content by 41%～77% and 57%～94%, respectively. The vermicompost reduced soil acidity significantly, and soil pH（H2O）value was 0.35～4 times higher than that of the control. For reducing acidity of the soil with 10% amount of vermicompost, the effect of cattle waste vermicompost was 22% higher than that of rice straw vermicompost. The vermicompost reduced the contents of soluble-exchangeable Cu and Pb in the soil by 19%～56% and 10%～40%, respectively, and increased the contents of organic state Cu and Pb by 22%～70% and 29%～70%, respectively. The vermicompost could significantly reduce the activity of Cu and Pb in soil. The effects of vermicompost on reducing Cu and Pb activity were 0.58～9.6 times and 0.16～3.4 times higher than those of the control. The effects of rice straw vermicompost on reducing activity of Cu and Pb were 11%～61% and 1%～32% higher than those of cattle waste vermicompost. In conclusion, vermicompost reducd soil acidity and Cu/Pb activity greater than that of control, cattle waste vermicompost was better on reducing soil acidity, and rice straw vermicompost was better on reducing Cu/Pb activity. The total organic carbon, microbial biomass carbon, Humic acid carbon and fulvic acid carbon in vermicompost all played important roles in reducing soil acidity. Cu and Pb activity, and the action efficiencies of organic carbon in the vermicompost on soil acidity and Cu/Pb activity were higher than those in the control material with the same amount of organic carbon.

Abstract:Based on the data of rainfall, throughfall, stemflow and climate at the II watershed of Huitong for Chinese Fir Ecosystem in 2015，we analyzed the canopy interception characteristics of Chinese fir forest, and the driving forces, and also verified the applicability of the Gash (1995) model to simulate the canopy interception. The results showed that: (1) The rain frequency was the highest in May and the amount of rainfall was the highest in August. In the whole year, the short-time light rainfall was the main form of single rainfall; (2) Throughfall, stemflow and canopy interception were positively correlated with the rainfall; (3) Gash (1995) model simulated annual cumulative canopy interception was 235.62 mm, which was in good agreement with the measured values (254.16 mm); (4) The accuracy of Gash (1995) model was mainly affected by canopy saturation capacity, annual evaporation and the ratio of average evaporation rate (E ?) to average rainfall intensity(R ?). In this study, the value S is reasonable, but the E ??R ? remains further to be more accurate.

Abstract:A field experiment was carried out to investigate the effect of wheat or rape straws incorporation into rice field on soil bulk density, soil nutrients, total organic carbon (TOC), active organic carbon (LOC), active organic carbon efficient (ACL), organic carbon stock (SCS), carbon management index (CPMI), rice yield in Hanzhong basin, Shaanxi Province, China. Soil samples were collected at the depth of 0—5 cm, 5—10 cm, 10—15 cm, 15—20 cm, and 20—25 cm soil layer. Results showed that the wheat or rape straw return significantly reduced soil bulk density in soil layer of 0—15 cm; however, wheat or rape straw return had no significant effect on soil bulk density in soil layer of 15—25 cm. Compared to the no straw return treatment, the soil organic carbon contents were significantly increased in the wheat or rape straw return treatments. Meanwhile, the soil TOC and LOC contents decreased with the increasing of soil depth in exception of soil layer in 0—15 cm, where both the contents were highest. The soil TOC had an obvious surface enrichment. The SCS content in soil layer of 0-30 cm was significantly increased by 21.9%～23.5% and 1.7%～6.7% in the wheat straw return treatments and rape straw return treatments, respectively. Compared to the rape straw return treatments, wheat straw returning significantly increased soil LOC, ACL, and CPIM in 10—15 cm soil layer; whereas, soil LOC, ACL, and CPIM in 15—25 cm soil layer in the rape straw returning treatment was higher than that in the wheat straw return treatment. Rice yield was highest in the straw returning treatment with decomposing agent than the straw returning treatment. Correlation analysis showed that rice yield positively related with the soil ACL. The straw return treatment can improve soil organic carbon, crop yield and is one of the most effective farming practices in the Hanzhong basin. Compared to the rape-rice rotation system, full wheat straw returning to field with rotary tillage significantly increased soil carbon sequestration and rice yield under the wheat- rice rotation system.

Abstract:In order to investigate the relationship between some properties of coal-based humic acids and arsenic availability in soil, and potential utilization and application direction of coal-based humic in the remediation and improvement of arsenic contaminated soil, a pot experiment was conducted to study the effects of four coal-based?humic acids on the content and speciation of arsenic in soil, the growth of pakchoi (Brassica campestris L. ssp.), and the adsorption and distribution of Arsenic in pakchoi. The results showed that No. 6 and No. 10 coal-based humic acids significantly reduced the contents of exchangeable Arsenic and carbonate bound arsenic, thus the content of available arsenic in soil was reduced significantly, meanwhile, the transfer and accumulation of arsenic from underground part to aboveground part of pakchoi were inhibited. The contents of exchangeable arsenic and available arsenic in soil and the total amount of arsenic in aboveground part of pakchoi in No. 10 coal-based humic acid treatment reduced 49.18%, 42.22%, and 15.17% than those in arsenic treatment, respectively. However, No. 9 and No. 11 coal-based humic acids increased the contents of exchangeable arsenic and carbonate bound arsenic, and significantly increased available arsenic in soil, and promoted the arsenic absorption, the transfer of arsenic from underground part to aboveground part of pakchoi. The contents of exchangeable arsenic and available arsenic in soil and the total amount of arsenic in aboveground part of pakchoi in No. 9 and No. 11 coal-based humic acids treatments increased 10.58% and 5.95%, 31.11% and 22.22%, 20.81% and 17.21% than those in arsenic treatment, respectively. The four coal-based humic acids all promoted the growth of pakchoi, and the promotive effect followed the order of No. 10＞No. 6＞No. 11＞No. 9. In conclusion, No. 6 and No. 10 coal-based humic acids, which had lower E4/E6 values, larger molecular weights, and lower contents of total acid base, had obviously inactivate effect on arsenic in soil, and could be used to control the arsenic absorption of crops and inhibit the transfer of arsenic from underground part to aboveground part of crops in mild arsenic polluted soil, so as to ensure crop safety production. No. 9 and No. 11 coal-based humic acids, which had larger E4/E6 values, lower molecular weights, and larger contents of total acid base, promoted arsenic activity and could be used as activator in moderate and severe arsenic polluted soil to strengthen phytoremediation.

Abstract:The concentrations of Al, Fe and Mn in Yellow Earth under the leaching environment was analyzed, and the effects of Epigallocatechin Gallate (EGCG) on the migration of Al, Fe and Mn under the interactions of concentrations and pH values. A completely randomized experiment with two factors was carried out, in which 48 EGCG solutions combined from different concentrations and pH values was designed to leach the Yellow Earth discontinuously. The concentrations of Al, Fe and Mn in leaching solutions were measured to analyze the migration volumes and migration processes of Al, Fe and Mn. The results indicated that the migration volumes of Al, Fe and Mn in Yellow Earth varied significantly under the interactions of concentrations and pH values. The EGCG solution with high concentration and high pH value would facilitate the migration of Al and Fe, whose volumes were 180.24 mg/L and 41.15 mg/L, respectively. However, the EGCG solution with high concentration and low pH value would be conducive to the migration of Mn, whose volume was 4.50 mg/L. The migration volumes of the three elements under the different interactions of concentrations and pH values followed the order of Al＞Fe＞Mn. Generally speaking, the concentrations of Al and Mn in the leachate decreased gradually in the middle-late leaching stage. However, the Fe concentrations in the leachate first increased and then decreased in the leaching processes, as the EGCG solutions with middle concentration and high pH, high concentration and high pH, and high concentration and middle pH; while the Fe concentrations showed a significant rising trend, when the concentrations of EGCG interacted with a lower pH value. It is suggested that the leaching of EGCG has a positive effect on the treatment of soil Al/Mn toxicity in a certain degree, especially at the early stage of leaching. Whereas, EGCG could not be used to control Al/Mn toxicity in soil at the same time.

Abstract:Based on meteorological and hydrological data of Xinqushou hydrological station in Gurt River in 1974 —2014, the cumulative trend, mutation characteristics and cycle variation of meteorological and hydrological factors were analyzed by cumulative anomaly method, Mann-Kendall mutation test and wavelet analysis. Meanwhile, the relationship between the meteorological hydrological factors of the Gurt River and Kuitun River and Ebinur Lake was analyzed. The results showed that: (1) In the last 40 years, the temperature, precipitation and runoff showed a trend of decreasing first and then rising, and the inter-annual variability was 7.95%, 15.84% and 6.68%, respectively; (2) Sudden changes occurred in the late 1980s, and the abrupt precipitation change time was earlier than the temperature (the early 1980s), and the runoff mutation time was at latest (the end of the 1990s); (3) Meteorological and hydrological factors showed a variety of different periods of oscillation cycle, while the most common interdecadal change cycle of temperature, precipitation and runoff was 25～28 years, 17～22 years, 4～6 years, respectively; (4) Runoff had a good correlation with air temperature, and its relationship with precipitation was complicated; (5) The trend of the runoff in Kuitun River was basically positive correlated with the Gurt River, and the main driving factor of the deterioration of the ecological environment in Ebinur Lake in the early 1970s was the overdevelopment by mankind.

Abstract:By using maximum temperature, minimum temperature and mean temperature, sunshine duration, evaporation, precipitation, relative humidity, and average wind speed of 5 weather stations in Irtysh river valley in Xinjiang from 1961 to 2013, the spatial and temporal trends of the temperature in this region were studied through taking the method of climate trending rate, 5 years running mean tread and Inverse distance weighted interpolation method. The main results were as followed: Diurnal temperature range (DTR) generally showed a reducing trend at scales of the year and decade, and except Altay City, the reduction trends of the rest regions in Irtysh river valley were all significant. Variation trends of DTR in each season were inconsistent, but generally showed reducing trend. Maximum and minimum values of annual DTR assumed reducing trend. Annual maximum and minimum temperature assumed increasing trend. Rapid increasing of minimum temperature and slow rising of maximum temperature were the direct causes of DTR decreasing. The average annual DTR was positively correlated with average temperature and average wind speed, and negatively correlated with sunshine duration, precipitation and relative humidity. Main factors affected the valley DTR were the average temperature, precipitation and average wind speed, and the strongest correlation factor was the average temperature, followed by precipitation. Main influence factor affected DTR varied from each station.