Abstract:Soil water is an important part of water resources and water cycle in nature. Moreover, the soil water condition is closely related to local crop production, eco-environmental quality and social-economic development. The soil water cycle and its mechanism can be explored by the application of stable hydrogen and oxygen isotope techniques from the both the macro and micro view. In recent years, the technology has gradually become an effective method for soil water cycle, especially for water migration and transformation. In this paper, the basic knowledge of hydrogen and oxygen isotopes in soil was systematically introduced. Then, the driving forces of hydrogen and oxygen isotope enrichment were analyzed based on the geochemical cycle of water, and the key points of isotope technique for soil water cycle were discussed. Finally, the future research was prospected.

Abstract:The effects of rainfall intensity and slope on erosion process for quaternary red soil was analyzed through indoor simulated rainfall test, and the test reveal the mechanism of slope erosion for quaternary red clay in hilly area of South China. According to the characteristics of topography and precipitation in the study area, we designed slopes of 10°, 15°, 20°, and rainfall intensity of 1.0, 1.5 and 2.0 mm/min to explore the influence of rainfall intensity and slope on the erosion process. The results showed that:(1) The initial slope runoff time decreased with the increase of slope and rainfall intensity; under the same rainfall intensity, the runoff coefficient was 20° > 15° > 10°; (2) While slope degree increased from 10° to 20°, the total amount of erosion and sediment yield increased by 0.46~1.98 times on the slope; when the rainfall intensity increased from 1.0 mm/min to 2.0 mm/min, the cumulative slope sediment yield increased by 1.37~3.85 times; (3) Under the condition of 1.0 and 1.5 mm/min rain intensity, the sediment yield on slope was dominated by <0.25 mm water-stable aggregates, and the water stability of > 0.25 mm was dominated by the slope erosion under the rainfall intensity of 2.0 mm/min; (4) The effects of slope and the rainfall intensity on runoff coefficient, erosion rate and cumulative sediment yield were significant (P<0.01),and the relationship between runoff and sediment yields could be described by power function. The results provide reference to reveal the mechanism of slope erosion in the quaternary red clay.

Abstract:To explore the similarity of the simulated rainfall experiments, based on literature data and observation data, this paper analyzed the differences of runoff and soil yield between indoor simulated rainfall experiments and natural rainfall observations in situ. The following results were obtained:(1) Simulated rainfall experiments could weaken the effect of rainfall on runoff and soil yield; the smaller intensity, precipitation amount or erosivity was, the lower similarity was to get. (2) The changing patterns of runoff and soil yield with the changing slope degree in the simulated rainfall experiments deviated from the patterns under natural rainfall. (3) While the conditions of the slope and the rainfall were identical, the soil yield from loessal sloping land under the stationary nozzle-type rainulator was far less than 50 percent of observations from natural rainfall. Consequently, there are some differences between simulated rainfall experiments and natural rainfall observations, and similarity merits future research.

Abstract:In order to explore nitrogen (N) output characteristics in double-rice cropping field during the process of the typical natural rainfall runoff, the long-term experiment with common urea (U) and reduction of controlled-release urea (CRU) was conducted to study the dynamics of total nitrogen (TN), ammonium nitrogen (NH₄⁺-N) and nitrate nitrogen (NO₃^--N) loss and loss ratio of runoff in paddy field. The results showed that N loss peaked in the early time of fertilization, which was the critical period to control N loss. NH₄⁺-N was the main form of N-applied treatments to runoff during early and late rice season, accounting for 64.5%~66.3% and 61.0%~68.6% in TN loss, respectively. The TN loss and loss ratios of runoff in U treatment during early and late rice season were 5.6 kg/hm² (2.2%), and 5.0 kg/hm² (1.7%), respectively. Compared with U treatment, TN loss in CRU treatments were reduced by 17.4%~34.1% and 17.3%~37.7%, and the TN loss and loss rates of runoff decreased with the decrease of N fertilizer rate. N loss in early rice season was higher than that in late rice season, and the inhibition of CRU treatments in N loss in late season rice was better than that of early rice season as affected by rainfall intensity. TN loss and grain yield in CRU treatments for earlyseason, late-season rice and the continuous cropping cycle had significant linear relationships with N fertilizer rate, which increased with the increasing N fertilizer rate. In conclusion, U treatment significantly increased N concentration and the ratio of NH₄⁺-N to TN in runoff. CRU effectively reduced N release rate and N loss in the early time of fertilization, and thus increased grain yield. The findings indicate that the reduction of CRU is helpful for further control of N loss risk in paddy field, and promote the reduction of agricultural non-point source pollution, especially in reduction of 10% N treatment.

Abstract:Through the simulations of freezing and water scouring test, two water discharges (1,2 L/min), two soil treatments (unfrozen slope, frozen slope) and four sand coverings (0, 1, 2, 3 cm) were compared to study the effects of the different treatments on runoff and sediment yield on the Loess slope. The results showed that:(1) Under the same flow conditions, the initial runoff time of the sand-covered slope was prolonged, and the extension effect was more obvious as the sand cover thickness increased, however, the initial runoff time was shortened by freeze-thaw action. When the peak value increased, the peak current time of output flow and sediment yield were asynchronous. (2) Under different flow conditions, the total output of different slopes was 1.02~1.28 times of that of the control slopes, then the total outputs of freezing slopes and freezing-covered slopes were significantly different from the control slopes (p <0.05). The total sediment yield of the slope was 1.97~10.94 times of that of the control slope. The total sediment yield of the frozen slope, the control-covered slope and the frozen-covered slope were significantly different from the control slope (p < 0.05). (3) Under the different flow conditions, the trend of runoff intensity of the same treated slope is roughly the same with runoff time. The trend of the runoff intensity of bare slope is steady with the runoff time; however, the runoff intensity's fluctuating degree is larger. Sand cover is the main factor affecting the sediment yield of slope. Under the same flow rate, the runoff intensities of different treatment slopes were roughly divided into two kinds, "rapid rise-relatively stable" and "relatively stable". (4) Under the same flow conditions, the runoff intensity on the bare slope was greatly influenced by the freeze-thaw action. The effects of freeze-thaw and the overburden slope on the sediment yield were large, and the effect of freeze-thaw on sediment yield was greater to bare slope than that to sand-covered slope. The effect of sand cover on the sediment yield was greater than that of the soil under unfrozen soil condition.

Abstract:Over-fertilization and straw returning were the vital issues that restrict the sustainable development of agricultural ecosystems in China. In this study, a process-based biogeochemical model-DNDC was adopted to simulate carbon (C) and nitrogen (N) loss from rice-wheat rotation system under different fertilization and straw returning measures, and then identify the best management practice in rice-wheat rotation system in Shanghai. The results indicated that reducing fertilization and straw returning could significantly impacts N loss, greenhouse gas (GHG) emissions and soil C storage in rice-wheat rotation ecosystem. Reducing fertilization by 25% combined with straw returning (75%CK+SR) was identified as the best management practice in rice-wheat rotation ecosystem by DNDC model, which could significantly reduce N loss by 41.67% and reduce N₂O emissions by 51.85%, respectively, while maintained the best rice yields. Straw returning would increase CH₄ emissions from rice-wheat rotation ecosystem, while significantly enhanced soil C storage. In addition, reducing fertilization by 50% (50%CK and 50%CK+SR) would lead to rice yields reduction by 3.06%~9.90%. Compared with traditional practice (CK), the identified best management (75%CK+SR) could efficiently improve ecological environmental benefit in the rice-wheat rotation. The results also provides reference for the control of C and N loss in the rice-wheat rotation in China.

Abstract:The present study aimed to reveal the effects of intercropping on soil runoff and lateral seepage nitrogen (N), phosphorus (P) loss in different types of slope farmland. A runoff and leaching simulating experiment was conducted, different types of soil (red soil and purple soil) and slopes (8° and 15°) and planting patterns maize (Zea mays L.)/soybeans (Glycine max L.) intercropping and mono-maize and mono-soybeans) were designed, the changes of N and P concentrations in runoff and lateral seepage under the influence of various factors were analyzed. The results showed that:(1) In the case of the total nitrogen (TN) and total phosphorus (TP) of runoff:under different slope in red soil, compared with mono-soybean, intercropping has different reduction effect on TN, the reductions were 27.5% and 30.8%, respectively, and the TN under intercropping was the lowest, which was 0.75 mg/L at the slope of 8°. Under the slope of 8° in purple soil, compared with mono-soybeans and mono-maize, the reduction of intercropping on TN of runoff was more obvious, and the reductions were 97.8% and 89.8%, respectively. Compared with mono treatment, intercropping had the different reduction on TP of runoff. However, the TP of runoff increased from the slope of 8° to 15°. (2) For the lateral seepage TN, TP, under the slope of 8° and 15° in the red soil, compared with mono-maize, intercropping had a greater reduction of the lateral seepage TN, which had 87.9% and 86.8% reduction, respectively, as well as the lowest concentration of TN was 2.91 mg/L at 8°; under the slope of 8° and 15° in purple soil, the reduction of intercropping on TN of lateral seepage were 50% and 80%, respectively. Compared with mono-maize, intercropping also had the different reduction on TP of lateral seepage; and the TP under the slope of 8° in red soil of intercropping was the highest with 0.25 mg/L, and the TP under the slope of 15° red soil of intercropping was the lowest with 0.07 mg/L. The output of N and P in soil was different under different slope treatments and the total loss of N and P in runoff or lateral seepage would increase with the slope increasing. In conclusion, the maize/soybean intercropping system had a certain effect on the reduction of N and P concentration in the runoff and lateral seepage. For red soil and purple soil, the reduction of the loss of N and P in the soil of slope farmland might be different because of their physicochemical properties. Therefore, controlling the loss of N and P in slope farmland should consider all kinds of factors, which is of great significance to protect the water environment of Dianchi Watershed.

Abstract:The application of new type fertilizer is of great importance to reduce nutrient runoff losses. A field experiment was conducted to investigate the effects of coated urea application on rice growth and runoff losses of nitrogen and phosphorus from paddy field. The experiment included five treatments such as CK (conventional fertilization), PU1 (59% P, 80% N with conventional urea), PU2 (59% P, 67% N with conventional urea), UR1 (59% P, 67% N with coated urea) and UR2 (59% P, 54% N with coated urea). Results showed that nitrogen and phosphorus contents in rice of PU1 and UR1 treatments were similar to CK, but the total nitrogen and phosphorus uptake of PU1 increased by 11.21 kg/hm² and 2.69 kg/hm², respectively with the comparison to CK. The shoot dry weight and grain yield of rice of PU1 and UR1 were higher than CK, as grain yield increased by 7.68% and 5.77%, respectively. Moreover, the content and the discharge of total phosphorus through runoff from paddy field of PU1, PU2, UR1 and UR2 treatments were lower than CK, which decreased by 13.18%~21.51%. The total nitrogen (TN), ammonium-N (NH₄⁺-N) and nitrate-N (NO₃^--N) concentrations in runoff of the treatments with coated urea (PU1, PU2) were lower than that with normal urea (CK, UR1, UR2), and TN, NH₄⁺-N and NO₃^--N cumulative losses decreased by 12.90%~26.91%, 54.52%~49.38% and 4.03%~15.95%, respectively, while the NH₄⁺-N cumulative losses of the treatments with normal urea were significant lower than that with coated urea (P<0.05). The application of coated urea and optimized fertilization can promote the uptake of nitrogen and phosphorus by rice, increase rice grain yield, significantly reduce the runoff losses of nitrogen and phosphorus in paddy field, which is worthy of application in rice production.

Abstract:Soil water and nutrient losses have played an important role in the research on the expansion of non-point source pollution, which also involved in soil erosion, hillslope hydrology and environmental management. Based on the simulated rainfall experiments on loess slope with spray-applied fertilizer (NH₄⁺-N,NO₃^--N,PO₄^3--P), the process of infiltration, soil erosion, and the solute transport process of soil water and solute on slope under interval rain events were investigated. The simulated rainfall experiments were carried out for three interval rain events. Specifically, rainfall intensity was designed as 100 mm/h, and the rainfall lasted 60 min, the rainfall interval was 60 min. Results were as follows:(1) The initial soil moisture content under the three rainfall events were different, but the runoff processes were similar, and the runoff rate showed an increasing trend at first and then tended to be stable. (2) For three interval rain events, the accumulation amounts of sediment were 250.91, 100.20 and 79.76 g, respectively, and the amount of accumulated sediment yield in the 1^st rainfall events was more than those of the 2^nd and 3^rd. The curve of sediment rate increased rapidly to the peak and then decreased slowly, and the average sediment yield decreased with the increase of rainfall frequency. (3) The concentrations of NH₄⁺-N, NO₃^--N were changed from high to low and gradually tended to be stable in three rainfalls. Compared with the NH₄⁺-N, NO₃^--N, the concentration of PO₄^3--P increased at the beginning of rainfall, and then lowered and leveled off. (4) The total loss of NH₄⁺-N, NO₃^--N and PO₄^3--P in surface runoff of three rainfall were 535.33 mg, 1 058.18 mg and 400.79 mg, respectively, and NO₃^--N have the most loss and PO₄^3--P have the least. With the increase of rainfall frequency, NH₄⁺-N, NO₃^-N and PO₄^3--P loss decreased gradually under different rainfall times, the loss amount were reduced 19% and 14%, 3% and 62%, 57% and 28.3% than previous rainfalls. The effects of three rain events on yellow soil of loess slope land reveal the interaction of rainfall, surface runoff and soil, and the mechanism of nutrient loss, also provide the scientific basis for control of water and soil erosion.

Abstract:Soil erosion model is a technical tool to calculate the soil loss and assess the efficiency of soil and water conservation practice. The universal soil loss equation (USLE) and Chinese soil loss equation (CSLE) were widely used to calculate the soil loss. The slope length in these models is significantly affected by the contributing area threshold. In this study, 210 small watersheds which area varied from 0.2 km² to 3.0 km² were selected to investigate the effect of contributing area threshold on the slope length and then the soil loss. The small watersheds are located in Northern rocky mountain area, Northwestern loess plateau, Northeastern black soil area, Southern red soil hilly area, Southwestern purple soil area, Southwestern mountainous area and Southwestern karst area. The 1:10 000 scale topographical map and 10 m×10 m DEM of the small watersheds were collected. 11 contributing area thresholds, namely, 1 000, 1 500, 2 000, 2 500, 3 000, 5 000, 7 000, 9 000, 11 000, 13 000, 15 000 m² were used to calculate the slope length and soil loss. The characteristics of slope length, soil erosion intensity and soil erosion area with the different contributing area thresholds were analyzed. The results showed that the average slope length and soil loss area firstly rose with the increase of contributing area threshold and then tended to keep constant. In the Northern rocky mountain area, Northwestern loess plateau, Northeastern black soil area, Southern red soil hilly area, Southwestern purple soil area, Southwestern mountainous area and Southwestern karst area, the average slope length with contributing area threshold of 15 000 m² was 1.53, 4.16, 1.95, 1.90, 1.69, 1.57, 1.47 times those of contributing area threshold with 1 000 m² and the soil loss area percentage with contributing area threshold of 15 000 m² was 1.20, 1.85, 1.43, 1.37, 1.77, 1.44, 1.30 times those of contributing area threshold with 1 000 m². The contributing area threshold had different effects in the different area. The average slope length and soil loss area in Northeastern black soil area was significantly affected by the contributing area threshold. The results will be helpful for calculating soil loss and for selecting the soil and water conservation practices.

Abstract:This study aimed to explore the influence of slope and flow on sediment transport capacity of colluvial deposits for rill erosion, calculate the rill flow sediment transport capacity accurately and establish rill sediment transport capacity factor model. The soil of colluvial deposit was taken as the case and a flume was used to conduct the experiment. The results showed that:(1) Rill flow sediment transport capacity increased with slope gradients at different flow discharge, which could be described by liner equation;(2) Rill flow sediment transport capacity increased with the increasing flow discharge at different slope gradients and the relationship could be described by power equation;(3) Rill flow sediment transport capacity factor model could be described by a dual binary power function, the index of flow rate (q) and slope (S) were 1.054 and 0.617 respectively. The effect of flow discharge was superior to slope gradient in the power function;(4) Compared with Wu model, ANSWERS model and Zhang model, the model of this study was more suitable to predicted sediment transport capacity of colluvial deposits for rill erosion.

Abstract:The shrub mound is a typical aeolian landform in the cross areas of wind-water erosion on Loess Plateau in China. Four sizes scale shrub mounds were selected to analyze the mound basic form, soil properties and correlations. The results showed:(1) The shrub succession significantly affected the development of mound. The mound volume was increased as the shrub biomass expansion. Until the shrubs succeeds in the stabilization phase, the mound volume tends to be stable (P < 0.05). (2) The amount, height and soil bulk density of the mound varied in the different position:the binding-sand quantity and height of the mound were the largest at the trap root, but were lowest in the edge. The soil bulk density showed the opposite characteristics. (3) The soil organic matter content of mound under the death, large, medium and small shrub patches were 1.54, 1.92, 1.46 and 1.30 times than the bare land, respectively; the soil moisture were 2.05,1.93,1.79 and 1.52 times than that of the bare land, respectively. (4) The soil moisture and soil organic matter content in the edge of the mound to three quarters of the trap root were higher than those in other positions of the mound.

Abstract:In order to study the effect of runoff and sediment yield on waste and slag formed from railway construction in Jiaodong Peninsula region, the artificial simulated rainfall experiments were conducted. According to the characteristics of rainfall and waste soil and slag in the study area, three different rainfall intensities with 20 mm/h, 40 mm/h, 60 mm/h and three slope gradients with 20°, 30°, 40° were designed. The results showed that both rainfall intensity and slope gradient affected initial runoff time, runoff, sediment yield, erosion amount and so on. (1) The initial runoff time decreased by 11~20 s with rainfall intensity increasing from 20 mm/h to 60 mm/h and shortened 17~22 s with the slope changing from 20° to 40°, respectively. (2) The runoff and sediment yield increased sharply to the peak during the early period of rainfall, and then the runoff gradually stabilized and the sediment yield decreased with the fluctuation and finally gradually stabilized. (3) Under the same slope gradient, the runoff in rainfall intensity with 40 mm/h increased 37.3%~122.6% compared with 20 mm/h and sediment yield was 1.5~19.5 times of that in 20 mm/h. However, the runoff in the rainfall intensity with 60 mm/h just increased 19.1%~26.7% compared with 40 mm/h, and the sediment yield was only accounting for 62.5%~151.8% of that in 40 mm/h. (4) Under the same rainfall intensity, the effect of slope gradient on runoff and sediment yield had a critical slope between 30° and 40°, and the runoff and sediment yield increased first and then decreased with the increase of slope. (5) When the slope gradient was 30°, the contribution of slope gradient to soil erosion was greater than the rainfall intensity, while the contribution of rainfall intensity obviously exceeded the slope gradient at 40°. The results can provide technical support for the soil and water loss monitoring and control during the construction process of the railway project in Jiaodong Peninsula region.

Abstract:Taking the typical engineering accumulation of urban construction and transportation hub project in Chongqing as case study, the infiltration characteristics, influencing factors and suitability of infiltration model were explored by using field double-ring infiltration, and the best infiltration model of typical engineering accumulation in Chongqing was filter out. The results indicated that:(1) The initial infiltration rate of engineering accumulation was 23.20 mm/min. The infiltration rate decreased gradually with time, and the 30 min-infiltration rate was 2.38~11.32 mm/min and the stable infiltration rate was 1.81~9.05 mm/min; (2) The initial infiltration rate, stable infiltration rate, average infiltration rate, 30 min-infiltration rate, 60 min-infiltration rate, and total infiltration of each engineering accumulation showed medium variation and the coefficient variation was 36.42%~57.49%; (3) The initial infiltration rate, stable infiltration rate, average infiltration rate, and total infiltration of engineering accumulation had negative correlations with soil bulk density and soil water content, while positive correlations with total soil porosity existed. The stable infiltration rate, average infiltration rate, and total infiltration of engineering accumulation had negative correlations with 60~40, 40~20, 20~10, 10~5 mm gravel content and had positive correlations with 5~2 mm gravel content; (4) There were differences in the fitting effect of the regression models with different engineering accumulations and the ranking of R² from high to low was:Kastiakov model (0.899) > common empirical infiltration model (0.893) > Horton model (0.870) > Philip model (0.867). The fitting effect of Kastiakov model was better than the common empirical infiltration model, Philip model and Horton model, and which could be used to simulate and predict the infiltration process and infiltration capacity of engineering accumulation in Chongqing.

Abstract:The hydrological condition of the near surface plays a vital role in the slope soil erosion process. The characteristics of soil erosion in saturated soil were different from that in unsaturated loess soil. In the study, loess soil was adopted in the well-defined rill simulation scouring experiment to explore the different hydrodynamic characteristics and flow resistance between saturated and unsaturated soil conditions. Results showed that the rill flow velocity of saturated soil had good power function with slope gradient and flow rate, and the slope gradient had a greater impact on the velocity. The rill flow velocity of saturated soil was about 1.17 times that of unsaturated loess soil, while the friction resistance of slope surface under saturated state was only 70.3% compared with that in unsaturated condition. Under the same conditions, the rill flow energy and sediment concentration of unsaturated soil were much lower than those of saturated soil. With the increase of rill flow energy, the sediment concentration of both kinds of soil showed a logarithmic growth, and the peak value of rill flow sediment concentration was stable at about 400 and 280 kg/m³, respectively. Saturated and unsaturated loess soil erodibility parameters were 0.088 and 0.057 kg/(m²·s), and the critical shear stress were 0.773 and 1.561 Pa correspondingly, indicating that saturated soil was much easier to be dispersed and eroded by water.

Abstract:Soil erosion and landslides occur occasionally in Beijing mountainous area, and vegetation is of great importance to control and predict soil erosion. Previous studies mainly focused on the estimation of total runoff volume (TRV) and total sediment yield (TSY), and the test and simulation of runoff process has been largely disregarded even neglected. The study was conducted in runoff plots in mountainous area in Beijing to examine the simulation accuracy of WEPP model on runoff process, TRV and TSY under different simulated rainfall intensities (5.7~75.6 mm/h), tree species (Pinus tabulaeformis, Quercus variabilis) and spacing (1.0 m×1.0 m, 1.5 m×1.5 m). Results indicated that:(1) Significant differences were observed in accumulative runoff between bare soil plot and forested plots under light rainfalls (gross precipitation ≤ 25.2 mm), while such differences were not captured in TRV and runoff coefficient. Both LAI and rainfall intensity significantly influenced TRV. (2) Though TSY in bare soil plot was 1.70 times larger than that in forested plots, no significant differences were found in ANOVA analysis, the soil loss rate (SLR) showed fine power relations with forest coverage in the equation SLR=e ^-0.02C; (3) Generally, the runoff process could be simulated accurately by WEPP model, yet the accuracy increased under heavy rainfalls (total precipitation was 49.8 and 75.6 mm). In contrast, the simulated time to runoff was 10~20 minutes later compared with the measured under light rainfall, and the simulated accumulative runoff was always higher than the measured value, and the gap between the simulated and measured increased with the increasing rainfall duration; (4) TRV and TSY were simulated well in WEPP model with CE of 0.61 and 0.91, respectively. Whereas the simulated TSY and TRV were 1.25 and 1.01 times larger than the measured values.

Abstract:This paper aimed at the problem that the calculation of siltation amount of silt dam caused by gravity erosion because of gully bank collapse and slope collapse during the operation of 5th sub-region silt dam on the Loess Plateau. By the method of actual measurement and 3S technique generation and original design of reservoir capacity curve, the silt blocking amount and soil erosion mode of silt dam during running period were checked and analyzed. The results showed that, (1) The morphological discriminant coefficient (α'), which reflects the silt form of silt dam, is between 0.711 and 208.517, and the mean value is 48.238. it indicated that the other silt dams were Delta deposition except Yangshan, which were the Vertebral siltation because the critical number were less than 2.2; (2) The shape parameters of dam controlling area, such as area of silt surface, circumference, silt volume and discriminant coefficient of silt form, had great influence on gravity erosion. The calculation relation of gravity erosion amount and erosion modulus were given; (3) The range of the modulus of gravity erosion is 184.79~812.80 t/(km²·a), the mean value is 360.68 t/(km²·a), and the range of modulus of siltation and sediment production in dam controlling area was 225~2 719 t/(km²·a), with a mean value of 1 382 t/(km²·a).The modulus of gravity erosion accounts for 26.1% of the modulus of sediment production. The above results showed that the reservoir sediment came from the hydraulic erosion and the gravity erosion of the reservoir area in the 5th sub-region of the Loess Plateau. The operation and management of the silt dam should prevent the gravity erosion from destroying the existing cultivated landand silt of channel base floweroded dam land. These could result in the silt dam being not able to be used efficiently.

Abstract:The characteristics of preferential flow dyeing and the influencing factors of two soils (leached cinnamon soil and fluvo-aquic soil) in Beijing were studied through field dyeing and tracing combined with indoor image analysis. The results showed that:(1) After the soils were dyed with 27.3 L of a brilliant blue solution with a concentration of 4 g/L, the average depth of matrix flow was 7.72 cm in the leached cinnamon soil and 8.56 cm in the fluvo-aquic soil, and the preferential flow in the latter relatively lagged. (2) The dyeing ratio, the maximum depth of dyeing and the length index in the leached cinnamon soil were greater than those in the fluvo-aquic soil, which meant the preferential flow phenomenon in the leached cinnamon soil was more obvious. (3) More concentrated preferential path areas and more developed lateral flow were existed in the leached cinnamon soil, also the correlation between dyeing ratio and soil depth in the leached cinnamon soil was more obvious than those of the fluvo-aquic soil. (4) Soil texture and soil organic matter were significantly correlated with the dyeing ratio (P<0.01) in two soils. The root length density of 1~3 mm in diameter and dyeing ratio were significantly correlated (P<0.05). The preferential flow phenomenon in the leached cinnamon soil was more obvious than that of the fluvo-aquic soil. The soil texture, soil organic matter and the root length density of 1~3 mm in diameter were the major influencing factors for the characteristics of preferential flow dyeing in two soils.

Abstract:In order to examine the soil water characteristic curve and its influence factors of granite benggang soil,the soil of collapsing gully wall in Anxi County of Fujian Province was taken as the object. Experiment on soil dehumidification was conducted by using the pressure membrane meter, and the soil water characteristic curve of the collapse wall soil was drawn, then the correlation analysis of the curve parameters and the influence factors was carried out. The results showed that the plastic index, clay contents, fractal dimension and roundness were all decreased generally with the increasing vertical depth of the collapsed wall soil. Meanwhile the slope of soil water characteristic curve increased with the increase of vertical depth of the collapsed wall soil, also the water holding capacity, the residual water contents and the VG model parameters a decreased, but the parameters n increased. The residual water contents and parameters (a, n) were all significantly correlated with bulk density and roundness. The residual water contents could be described by bulk density and clay content, the parameter a could be described by bulk density and shape ratio, the parameter n could be described by bulk density and plastic index. The findings can provide reference for the strength test of collapse wall unsaturated >

Abstract:The experiments of fertilizer infiltration through muddy water film hole with four diameters (6, 8, 10 and 12 cm) were carried out in lab using Xi'an silty loam soil. Migration distance of the wetting front, cumulative infiltration, soil water distribution in the wetted body and transport characteristics of and were observed and analyzed. The results showed that:The film hole diameter had a significant effect on transport characteristics of water and nitrogen under the muddy water film hole irrigation. The cumulative infiltration amount of fertilizer through muddy water film hole with different diameters conformed to Philip infiltration model. There was a significant power function relationship between migration distance of the wetting front and infiltration duration. Within the same infiltration time, cumulative infiltration volume of per unit area gradually decreased with the increasing of film hole diameter, while migration distance of the wetting front and contents of NO^-₃-N and NH⁺₄-N in the same position increased with the increasing of film hole diameter. Content NO^-₃-N and NH⁺₄-N were both higher in the center of the film hole within 400 minutes of infiltration. The soil NO^-₃-N in the wetted body was mainly distributed in the range of 15 cm from the center of the film hole, and NH⁺₄-N in the wetted body was mainly distributed in the range of 8 cm from the center of the film hole.

Abstract:Based on the monthly precipitation data of 22 meteorological stations in three outlets region along Jingjiang reaches of Yangtze River from 1951 to 2016, the characteristics of drought-flood variation during 66 years were analyzed by using the standardized precipitation index (SPI), long cycle drought-flood abrupt alternation index (LDFAI), EOF (empirical orthogonal function) analysis, Morlet wavelet analysis and M-K (Mann-Kendall) test. Results showed that:(1)There were large inter-annual variations. Specifically, drought after flood in 1950s, entire drought in 1960s and 1970s, alternation of drought and flood in 1980s, entire flood in 1990s, drought after flood in 2000s, and even-distributed drought-flood in any seasons.(2) Spatially, there were three types of drought-flood in the area, i.e. the flood-prone southeastern zone, the central zone with normal precipitation, and the drought-prone northwest zone, which had distinct seasonal distribution patterns of drought-flood. (3) Frequencies of some 5 and 10 years could be conceived, and stable frequencies of 30~35 years were significant. (4) The LDFAI index was changed in 1981 and 2015, while the intensity changed in 1972 and 2014. (5) In summer, the precipitation in Yichang, Shimen and Lixian changed from drought to flood, while the trends were opposite in and that i Wufeng, Ningxiang, Anxiang, Huarong and Changde.

Abstract:In six structurally packed columns (two homogeneous and four heterogeneous) constructed with two kinds of glass beads, we studied the effect of media heterogeneous on the transport behaviors of tracer and montmorillonite colloids in saturated condition. The results showed that the breakthrough curves of tracer were similar in two homogeneous columns, and the mobility of montmorillonite colloids in coarse media was stronger than that in fine media. For the column containing macroporous channel, the presence of preferential flow path resulted in an earlier breakthrough of tracer and montmorillonite colloids, and larger contact area between macroporous channel and fine grains caused a lower breakthrough peak and a stronger tailing. In column packed with homogeneous mixture of coarse and fine grains, the shape of tracer breakthrough curves were similar to that in homogeneous columns, and the mobility of montmorillonite colloid was between that in the homogeneous columns (coarse and fine grain). More montmorillonite colloids were retained at coarse-fine grain interface in the layered column. The results have shown that heterogeneity has an important effect on the transport of the tracer and montmorillonite colloid in soil and underground environment.

Abstract:Using rain recorder and filter paper stain method, the effects of evergreen broad-leaved forest on raindrop kinetic energy of Mopan Mountainin Yunnan Plateau were explored, during the period from May to Sep in 2016 and 2017. The results showed that the number of raindrops was more than troughfall raindrop by 61.7%. With the increase of rainfall, the raindrop diameter increased gradually. Raindrops with diameter <0.5 mm of outside of forest accounted for 40.85% of total number of raindrop in the light rain condition, while the proportion was only 12.22%, and the number of raindrop with 0.5~3.5 mm diameter accounted for a larger proportion than outside forest. When raindrop diameter >4.5 mm in outside forest, the raindrop terminal velocity stabilized around 9.34 m/s. When raindrop diameter >4.1 mm, the speed was about 7.05 m/s. Rain kinetic energy at the rainstorm condition was larger than it in light rainfall by 98.29%.and with the increase of rainfall, the peak in cumulative raindrop kinetic energy reached 20.68% rainfall outside of the forest. With the increase of raindrop diameter, the throughfall potential energy, total rainfall potential energy and canopy interception potential energy both showed a gradual increase trend. The buffering potential energy was 46.59% larger than that of penetrating rain potential, accounting for 65.18% of the total potential energy. The canopy layer has the function of retention and increase of raindrop, which also cause the rainfall lag in forest, and the had obvious buffering effect on the rainfall speed, potential energy and kinetic energy of natural rainfall.

Abstract:The effects of nano-carbon on soil water infiltration, soil water characteristic curve and soil water distribution were studied by TDR and tensiometer through one dimensional vertical soil column test. The results showed that:(1) With the increasing of infiltration time, the cumulative infiltration amount of the soil contained nano-carbon decreased in the same infiltration time, and the advancing distance of wetting front decreased obviously, and the application of nano-carbon presented obvious infiltration reduction effect. Using Philip infiltration model to fit infiltration data, the infiltration rate S decreased with the increasing of nano-carbon content, meanwhile with the increasing of nano-carbon content, the cumulative infiltration amount decreased gradually in the early stage of water infiltration. The linear fitting of wetting front in different layers showed that infiltration rate decreased significantly when wetting front entered second layers of soil, and nano-carbon layer had obvious effect of water blocking. (2) Adding nano-carbon, the water content of nano-carbon composite layer increased obviously, and soil water content in the lower layer of the nano-carbon composite layer was lower than that in the blank control group. When the nano-carbon content was 0.5%, the soil water content of the nano-carbon composite layer was the maximum. (3) Adding nano-carbon could significantly improve the water holding capacity of soil when the soil was under dehydration condition; the soil water characteristic curves were fitted using the van Genuchten model, and the soil water retention rate(θ_r), saturated water content (θ_s) and the correlation coefficient (α) of the formula significantly increased compared with the soil without nano-carbon, and the shape coefficient n was smaller than that of the soil without nano-carbon.

Abstract:In order to study the water holding capacity of the litter of Pinus massoniana plantation in different forest types in the Three Gorges Reservoir Area, the methods of field survey and soaking extraction was applied to study the water holding capacity of P. massoniana plantation (Ⅰ), P. massoniana + Toona sinensis mixed forest (Ⅱ), P. massoniana + Sassafras tzumu mixed forest (Ⅲ), P. massoniana + Rhus chinensis mixed forest (Ⅳ), P. massoniana + Quercus aliena + Sassafras tzumu mixed forest (Ⅴ), P. massoniana + Betula luminifera mixed forest (Ⅵ), P. massoniana + Litsea pungens mixed forest (Ⅶ). The result showed the litter amount in different types of P. massoniana forest in the Three Gorges Reservoir Area ranged from 5.39 t/hm² to 11.77 t/hm², the litter thickness ranged from 2.14 cm to 3.73 cm, and the order of total litter amount was Ⅲ > Ⅳ > Ⅵ > Ⅱ > Ⅴ > Ⅰ > Ⅶ, the maximum water holding quantity ranged from 11.94 t/hm² to 23.42 t/hm², the maximum water holding rate ranged from 198.53% to 266.17%. The effective interception of the seven types of P. massoniana forest litter ranged from 8.34 to 15.90 t/hm², and the effective interception rate ranged from 135.79% to 195.81%, the effective interception of litter and the maximum water holding quantity, all showed Ⅲ > Ⅴ > Ⅳ > Ⅰ > Ⅱ > Ⅵ > Ⅶ. However, except for Type Ⅶ and Type Ⅱ, the effective interception rate was consistent with the maximum water holding rate of other types. The water holding capacity of seven types of P. massoniana plantation increased logarithmically with the soaking time. After soaking for 5 minutes, the water absorption rate of litter in different forest types was the highest, and it showed slow decline after soaking for 1 hour. The water absorption rate V and socking time t fit better with power function, and the water absorption rate decreased with the prolongation of the soaking time in power function form.

Abstract:This study, taking the litter layer of rhododendron forest with mild, moderate, and severe interference intensity as the research object, analyzed the hydrological function characteristics of the litter layer of different interference intensity on the basis of indoor immersion method, aimed to reveal the influence of artificial tending and tourism management on the function of soil and water conservation of rhododendron forest in Baili Rhododendron nature reserve. The results showed that:(1) The litter reserves decreased with the increase of interference intensity, while it increased significantly with the increase of decomposition degree; natural moisture content decreased with the increase of interference intensity, and increased with the increase of decomposition degree. (2) The maximum water-holding capacity of rhododendron forest litter decreased with the increase of interference intensity, and increased significantly with the increase of decomposition degree. The maximum interception amount, maximum interception rate, effective interception amount, and effective interception rate of litter rose with the increase of interference intensity. (3) The water-holding capacity variation of litter layer manifested as an inverted "J" feature. The water-holding capacity of litter layer (Q) was positively correlated with soaking time (t) (P<0.05), and the regression equation was Q=b+aln t. The water-holding capacity increased gradually in the soaking time interval of 0~4 h, whereas the increase rate became slow in 4~48 h and then approached to saturation. (4) The water absorption rate of the litter layer was characterized by the cycles of "sharp reduction-rapid reduction-slow reduction-tending to stabilization". The water absorption rate (v) was significantly negative correlated with soaking time (t)(P<0.01), and the regression equation was v=at^-b. The litter had the strongest ability to play its hydrological function in 1h and showed the greatest function of rainfall interception in a short period of time.

Abstract:In order to understand the characteristics of carbon, nitrogen, phosphorus, and the stoichiometry characteristics of Pinus sylvestris var. Mongolica plantation ecosystem in Horqin Sandy land, we used the space-temporal exchanging method and selected four forests with different stand ages (15, 25, 35, and 45 years) but with similar site condition as the objects. The contents of carbon, nitrogen, phosphorus, and the stoichiometry characteristics in the needle leaf, litter, and soil were analyzed, then their changing characteristics as stand age increasing and the relationships between them were explored. The results showed that:(1) The contents of C, N, and P were in order of needle leaf > litter > soil, C/N, C/P, and N/P were in order of litter > needle leaf > soil, whose differences were significant among needle leaf, litter, and soil. (2) There were significant differences for C, N, P concentrations, and C/N, C/P stoichiometry ratios among forests with different stand ages. The C, N, and P contents of leaf, litter, and soil were the highest in the 35-years-old forest. (3) Compared to other regions, the leaf and litter performed the same characteristic with higher C and P, lower N, higher C/N, higher C/P and lower N/P. (4) The N/P ratios of all forests with different ages were lower than 14, but there was no significant difference between them, which indicated that the P. sylvestris plantation was restricted by N, but the N limitation was not significant between forest ages. (5) There were significant correlations between the contents of C, N, P and C/N, N/P ratios of the leaf, litter and soil, which indicated that the C, N, P elements of P. sylvestris plantation were transferred between 3 libraries of the conifer, litter, and soil, but its internal maintenance mechanism needs further study.

Abstract:Application of Disc permeameter in field and sandbox-pressure chamber in door was used to determine hydraulic parameters and pore size distribution for soil samples of various aged plateau zokor mounds on Zoige grassland. Compared to the control grassland soil, the water content in structural pores (θ_str) of mounds increased, while the water content in soil textural pores (θ_txt) decreased from (0.14±0.02) cm³/cm³ to (0.10±0.02) cm³/cm³, indicating a potential of a quicker water infiltration through mound soil via soil structural pores. In soil with newly-formed mound and one-year-old mound, the effective porosity of soil pores with size r > 250 μm increased by 30% and 11%, and the saturated hydraulic conductivity increased by 38% and 21%, respectively, compared to the control soil. Therefore, it can be concluded that the excessive activity of zokor has changed soil pore structure, caused a decrease in soil's capacity to hold plant-available water and thus may accelerate the degradation and desertification of Zoige grassland.

Abstract:The field experiment with different planting patterns (maize monoculture, maize//soybean intercropping and maize//potato intercropping) of maize was carried out, and root exudates of total sugars and total organic acids and soil aggregates at jointing, bell-mouthed, and tasseling stages of maize growth were measured. The influence of intercropping on maize root exudates and soil aggregate stability was explored. The results showed that root exudates of total sugars and total organic acids increased with maize growth. Intercropping significantly increased maize root exudates of total sugars and total organic acids. Maize//potato intercropping was better than maize//soybean intercropping. Compared with maize monoculture, maize//soybean intercropping and maize//potato intercropping have increased >0.25 mm water stable aggregate (R_0.25) by 6.19% and 8.17%, mean weight diameter (MWD) by 5.04% and 10.08%, geometric mean diameter (GMD) by 6.12% and 12.24%, have significantly decreased fractal dimension (D) by 0.72% and 1.09%, and portion of aggregate destruction (PAD) by 16.77% and 26.08%, respectively at tasseling stage. At tasseling stage with maximum root exudates, total sugars content and total organic acids content were significantly correlated with R_0.25, GMD, D, and PAD (P<0.01). These results indicate that intercropping can enhance maize root exudates of total sugars and total organic acids and thus improve soil aggregate stability.

Abstract:This study evaluated the effects of artificial Haloxylon ammodendron plantation on the concentrations and storages of soil organic carbon (SOC), soil inorganic carbon (SIC), total nitrogen (TN) and total carbon (TC) by field investigation and laboratory analysis in Minqin desert regions. And the ages of H. ammodendron plantations were 4,13, and 36 years old, respectively. Results showed that the concentrations of SOC and TN in soils of 0-50 cm depth under shrubs and between shrubs both increased with the increasing of plantation age after afforestation, whereas the highest concentrations of SIC in 5-50 cm depth soil under shrubs were observed in 13-year-old plantations. Generally, the storages of SOC and TN were both higher under shrubs than those of between shrubs in 13- and 36-year-old plantations. However, the storage of SIC was less under shrubs than that between shrubs in 13-year-old plantations. And in the soils of 5-50 cm depth, the storages of SOC, SIC and TN were less under shrubs than those of between shrubs in 4-year-old plantations. In the soils of 0-50 cm depth, the storages of SOC, SIC and TN increased by 102.44%, 24.66% and 54.55%, respectively, after afforestation. Additionally, the storages of SOC and TN declined firstly and then increased with the increasing of soil depth in 36-year-old plantation, whereas the storages of SOC, SIC and TN all increased with the increasing of soil depth in shifting sandy land, 4- and 13-year-old plantations. Overall, the proportion of SOC to TC increased with increasing of afforestation age. Pearson's correlation analysis indicated that storages of SOC and TN were both significantly correlated with soil particle size distribution, soil bulk density, plantation ages and soil depth. Therefore, we concluded that afforestation in arid desert region largely improved the accumulation of soil organic carbon and total carbon pools, and the carbon storage of soil increased with the growth of forest age.

Abstract:The stability of soil aggregates provide physical protection for soil carbon, while soil carbon promotes the formation of soil aggregates. To evaluate the effects of long-term straw and quicklime application on soil aggregates stability and total carbon (TC) accumulation at aggregate, soils from plots amended with M (chicken manure), MR (chicken manure + straw), MCa (chicken manure + quicklime), MRCa (chicken manure + straw + quicklime) were collected compared with CK (no-fertilizer). Soil was separated into five size fractions (5~2, 2~1, 1~0.5, 0.5~0.25, < 0.25 mm) by wet-sieving. The results showed as follows:(1) Straw return or liming increased the distribution of > 0.25 mm size fractions, MR and MCa caused 123% and 37% increase relative to the M, respectively; while application of straw and quicklime together had a significant effect on the distribution of 5~2 mm size fraction, compared with MR, MCa and M, the MRCa caused 12%, 59% and 141% increase, respectively. (2) Application of straw and quicklime could increase the MWD, GMD and R_0.25. MR treatment had the highest MWD, GMD and R_0.25, followed by the MRCa treatment, MR and MRCa were significantly higher than those of MCa, M and CK. (3) Addition of straw and quicklime could increase the TC content, compared with MR, MCa and M, MRCa caused 20%, 40% and 55% increase, respectively; straw return and liming significantly increased the TC content of 5~2 mm size fraction; liming could increase the TC content of 0.5~0.25 mm size fraction; both straw and lime could significantly increase the contribution of TC in the >0.25 mm size fractions to the bulk soil TC. (4) TC content was positively correlated with the distribution of 5~2, 2~1, 1~0.5 mm size fractions, and negatively correlated with the distribution of < 0.25 mm size fraction. MWD, GMD and R_0.25 were positively correlated with the distribution of > 0.25 mm size fractions, and negatively correlated with the distribution of < 0.25 mm size fraction. Therefore, straw return and liming could improve the soil structure and carbon level. These findings were beneficial to alleviate the problem of soil structural fission caused by long-term continuous cropping in the agricultural production of greenhouse.

Abstract:In order to study the contents and dynamic characteristics of soil light and heavy fraction organic carbon during the vegetation degradation process, the filed and laboratory experiments were conducted in marsh meadow of Gahai wetland in Gannan state, Gansu province. The main results were as follows:The soil light fraction organic carbon contents in 0-20 cm layers varied in different stages of vegetation degradation of marsh meadow, following the order of UD (undegraded) > LD (lightly degraded) > HD (heavily degraded) > MD (moderately degraded). The soil light fraction organic carbon in 20-100 cm layer was less effected by vegetation degradation. The soil heavy fraction organic carbon contents HD and MD stages of vegetation degradation were significant higher than UD and LD in entire soil layer (P<0.05). With the increasing soil layers, all the soil light and heavy fraction organic carbon contents significantly decreased. The soil light and heavy fraction organic carbon showed the obvious dynamic characteristics with time in all stages of vegetation degradation. The soil light fraction organic carbon contents gave a trend of "down-up-down" in UD stages of vegetation degradation in 0-20 cm soil layer, i.e., the highest in May, the lowest in July and September. But the contents were reduced and stabilized in June in the other stages of vegetation degradation. The variations of soil light fraction organic carbon contents was small in 20-100 cm soil layers. The variations of soil heavy fraction organic carbon contents were consistent in all stages, giving linear decreases with time, the significant difference occurred between different months (P<0.05). These findings indicated that vegetation degradation could result in the decreases of soil light fraction organic carbon, and the increases of heavy fraction organic carbon. However, the main consumption of soil organic carbon is the light fraction, and the heavy fraction is relatively stable. Correlation analysis showed that the changes of underground biomass and soil moisture contents had significant influence on soil light and heavy fraction organic carbon.

Abstract:In order to provide a scientific basis for the promotion of soil fertility and the sustainable development of agriculture, a fixed site field experiment was conducted to investigate the changes of soil microbial biomass carbon, nitrogen and dissolved organic carbon after long-term (six years) straw return and urea application in a winter wheat-summer maize rotation system from Guanzhong Plain in Northwest China. The experiment was arranged in a split block design with two main treatments and three subplots, full maize straw return of previous crop (S+N) and no straw return (N) as main plots, and three chemical nitrogen treatments 0, 168 and 252 kg/hm² with four replicates as sub-plots. The results showed that with time soil MBC decreased from tillering stage to wintering stage, then increased until jointing stage and declined later. Soil DOC increased from tillering stage to jointing stage and decreased later with time, the dynamic change of soil MBN in the whole wheat growing season showed a decreased trend. Compared with no straw return treatments, straw return significantly increased the MBC and DOC content in the soil, and increased by 6.7% and 9.3% in average, respectively. MBN in straw return treatments were higher than no straw return treatments, but significantly increased only in wintering stage, jointing stage and maturity stage. With the increase of nitrogen rate, MBC and MBN significantly decreased. While with the increase of nitrogen rate, DOC significantly increased in straw return treatments, and increased by 11.8% in average, but the DOC in no straw return treatments showed an increased trend firstly and declined later. Overall, straw returning could obviously increase soil microbial biomass carbon, nitrogen and dissolved organic carbon, and the application of chemical nitrogen fertilizer promoted the decomposition of maize straw, but excessive application of chemical nitrogen fertilizer decreased the microbial biomass carbon and nitrogen, and will have negative effect on the growth of microorganism. So, straw returning with moderate nitrogen fertilizer is an effective measure to improve the soil fertility and realize the sustainable development of agriculture in the winter wheat-summer maize rotation system from Guanzhong Plain in Northwest China.

Abstract:Four different forest lands were chosen in the hill region of central Hunan, China. They were:Loropetalum chinense-Vaccinium bracteatum.-Rhododendron mariesii scrub-grass-land (LVR), L. chinense-Cunninghamia lanceolata-Quercus fabri shrubbery (LCQ), Pinus massoniana-Lithocarpus glaber-L. chinense coniferous-broad leaved mixed forest (PLL) and L. glaber-Cleyera japonica-Cyclobalanopsis glauca evergreen broad-leaved forest (LAG). In order to elucidate the effects of forest degradation on soil organic carbon, the soil partical-size fractionation method was adopted to study the changes of soil organic carbon (SOC) concentrations and their distributions in different particle-size fractions in the mid-subtropical zone of China. The result showed that the percentage of > 2 μm particles (sand, silt) increased, while that of < 2 μm clay particles decreased, and soil texture was coarse sand with the degradation of forest land. SOC concentration had the negative exponential function decreasing trend with the degradation of forest land. SOC pool was mainly composed of silt-C and clay-C in LAG, while those were dominated by silt-C and sand-C in PLL, LCQ and LVR. With the degradation of forest land, Concentrations of SOC in three partical-sized fractions were decline, the distribution proportion of sand-C concentrations increased obviously, but that of clay-C decreased obviously, and the ratio of POC/MOC increased, the SOC fixation, protective effect, stability decreased in the same layer. The changes of community species composition, biomass and soil particles composition with the degradation of forest land were the main factors leading to the decrease of SOC contents and stability of forestlands.

Abstract:To relieve the characteristic conflict that the extremely scarce water resource cannot satisfy the large water requirement for wheat and maize double cropping production in the North China Plain (NCP), a field experiment was conducted in Xinji County and Shenzhou County which are located in Hebei Plain and represent the northern part of the NCP. Under conventional (-PM) and SUPM (+PM) conditions, two cropping systems were set, which were a conventional annual winter wheat-summer maize double cropping system (W-M) and a winter wheat-summer maize-spring maize triple-cropping system over 2 years (W-M-M), respectively. The results indicated that under SUPM the average wheat grain yield decreased by 3.9%~4.8%, and that of summer maize increased by 5.1%~6.0% compared with un-mulching treatment. There was no significant difference between SUPM and no mulching in total yield in the 1st year. Compared with summer maize, the spring maize yield increased by 16.9%~24.6%. Howerer, in a 2-year cycle the triple cropping system sacrificed 13.4% of grain yield compared with the double cropping system. The average annual evapotranspiration (ET) of the conventional double cropping was 859.9 mm. Under the triple cropping system over 2 years, the ET was decreased by 15.5% and the water use efficiency (WUE) was not increased significantly due to its lower yield compared with the conventional double cropping. SUPM led to an annual ET decrease of 200 mm, and the WUE increased by 28.4%~36.0%. The results also demonstrated that SUPM was better at water saving in the winter wheat season than in the summer maize season. Reduced ET in the non-growing period (the gap from the previous summer maize harvest to subsequent spring maize sowing) was also the key factor for water saving under the triple cropping system. The field water deficit was 616.6~799.0 mm in the conventional double cropping over a 2-year cycle, and it was decreased by 38.6%~55.8% in the triple cropping without SUPM. Under SUPM the field water deficit was 56.8%~73.5% lower than that under non-SUPM treatments. In the triple cropping system under SUPM, both groundwater and field water balance were almost achieved with an average annual precipitation of over 560 mm. SUPM and reducing harvest frequency could balance the vertical distribution of soil water and reduce water loss near the soil surface. The triple cropping system under SUPM over 2 years could be regarded as a new method for sustainable agricultural water utilization and food production in NCP.

Abstract:To explore the unity use patterns of water and nutrients in Hani terrace, reveal the spatial and temporal variation of nitrogen, clarify the impact of land use on nitrogen concentration, and provide scientific basis for water environment protection and sustainable development, we used QuanFu zhuang watershed as the research object, analyzed the characteristics of spatial and temporal distribution of surface water nitrogen. The research showed that (1) Except for the strong variation of NO₃^--N concentration in summer and winter, the coefficients of variation of other N concentrations in different seasons were less than 100%, and showed a moderate variation. (2) The variations of the concentration of TN, NO₃^--N and NH₄⁺-N concentration in the lower part of the terraced fields were (0.103~0.849, 0.010~0.143, 0.052~0.446 mg/L) relatively large, and the variations of the concentration of TN, NO₃^--N and NH₄⁺-N concentration in forest surface water were (0.108~0.471, 0.003~0.102, 0.058~0.164 mg/L) relatively small. (3) The nugget coefficients of TN, NO₃^--N, and NH₄⁺-N were less than 50% in each season, and showed a strong spatial correlation in each season. The variation ranges of TN, NO₃^--N, and NH₄⁺-N were all within 1 000 m in each season, indicating that the variation was distributed continuously in different scales in each season and there was spatial autocorrelation. (4) Through Kriging interpolation, the overall TN, NO₃^--N, and NH₄⁺-N concentration in surface water of different seasons ranged as village > woodland > terrace > rivers.

Abstract:In order to clarify the effects of crab activities on the changes of available nutrients in wetland soils, soil DOC, MBC, NH₄⁺-N, NO₃^--N, Fe and their valence contents under the interference of crabs from different tidal flats in Minjiang River estuarine wetlands were measured. The results showed that the average contents of DOC and MBC in soil were 95.98 and 11.13 mg/kg, respectively in the crab group and 106.99 and 7.54 mg/kg in the control group, respectively (P<0.05). The content of MBC in soil of crab group was higher than that of control group (P<0.05). The highest and lowest values of the two contents appeared in summer and winter respectively, and were significantly higher in summer than in other seasons (P <0.05). The average values of soil NH₄⁺-N and soil NO₃^--N in the crab group were 22.45 and 1.08 mg/kg, respectively, and those in the control group were 23.65 and 1.44 mg/kg. The content of NH₄⁺-N in soil of crab group was lower than that of control group (P<0.05), while the content of NO₃^--N in soil of crab group was lower than that of control group (P<0.05). The contents of NH₄⁺-N and NO₃^--N in soil were significantly different in different seasons (P<0.01). The soil total iron content in crab group was slightly higher than that in control group (P>0.05). The content of Fe²⁺ in soil of crab group was significantly higher than that in control group (P<0.05). There was no significant difference in soil Fe³⁺ content between crab group and control group (P>0.05). In different seasons, soil total Fe, Fe²⁺ and Fe³⁺ contents were significantly different (P<0.01).

Abstract:In order to explore the temporal and spatial variation characteristics of soil nutrients and their ecological stoichiometry in different disturbed alpine grasslands in East Qilian Mountains. The soil nutrient content and its ecometrics characteristics of different disturbed alpine grasslands in Eastern Qilian Mountains in August 2017 were studied. Compared with the same sites in 2003 and 2011, the same research methods were used to compare the soil physical and chemical properties in this area. Results showed that:(1) Soil pH value, electroconductibility, water content, soil total amount and available nutrient all decreased with the depth of soil and varied with different soil layers in the same disturbed habitat. (2) The soil C/N ranged from 7.64 to 18.21 in different disturbed habitats, which was basically close to the average value (10~12) of land soils in China. The soil C/P and N/P that ranged from 109.16 to 144.79 and 7.52 to 15.65 respectively, was much higher than the average C/P of 52.7 and N/P of 3.9 in China. (3) The principal component analysis showed that the physical and chemical properties of soil (pH, electrical conductivity, water content, total phosphorus, total potassium, available phosphorus, organic matter, organic carbon and available nitrogen) and ecological stoichiometry ratio (C/N, C/P and N/P) in the soil could sensitively reflected the different disturbance on grassland soil quality. The comprehensive evaluation of soil quality showed that the difference of grassland soil quality under different disturbed habitat vary greatly, the perennial grassland soil quality is higher, and the grass quality outside the fence is the worst. At 0-20 cm and 20- 40 cm soil layer, soil quality ranged as perennial cultivated grassland> inside the fence grassland> Annual cultivated grassland> outside the fence grassland. (4) Compared with 2003 and 2011, the pH value and water content of four different disturbed alpine grasslands showed an overall upward trend, while the content of soil organic matter, total nitrogen and total phosphorus showed a significant downward trend. In summary, grazing disturbance and artificial planting had a great impact on the soil nutrient content of four disturbed grasslands in the eastern Qilian Mountains. Therefore, adequate attention should be paid to the utilization and conservation of the grassland in this area, and the grasslands should be rationally utilized and scientifically managed.

Abstract:The effects of different kinds of organic manures (compost manure, chicken manure, cow manure, and pig manure) application on organic carbon (C) concentrations and humus composition in bulk soil and its different size aggregate fractions were studied based on field location experiment in a black soil with organic fertilization at the Jilin Academy of Agricultural Sciences. The results showed that, compared with no fertilizer (CK) and single application of chemical fertilizers (NPK), the application of organic manures in combination with chemical fertilizers increased significantly (P < 0.05) the concentrations of organic C, humic acid C (HAC) and humin C (HUC) in bulk soil. Meanwhile, the concentrations of organic and humic C within different size aggregate fractions also increased after the combined application of organic manures with chemical fertilizers compared to CK and NPK treatments, with significant increase for organic C, HAC and HUC within different size aggregate fractions following compost manure application. Among the experimental organic manures, the concentrations of organic C, HAC and HUC were higher for compost manure than for other organic manures treatments, with significant difference between compost manure and cow manure treatments. With respect to other organic manures treatments, > 0.25 mm aggregate-associated organic C concentration was higher after the application of compost manure and cow manure, with significant difference between compost manure and cow manure with chicken manure treatment for 2~0.25 mm aggregate fraction. Moreover, the concentrations of HAC and HUC in 2~0.25 mm aggregate fraction were significantly higher for compost manure than for pig manure treatment, whereas the concentrations of HAC 0.25~0.053, <0.053 mm aggregate fraction were significantly lower for compost manure than for chicken manure treatment. The above results indicated that the combined application of organic manure with chemical fertilizers increased the concentrations of organic and humus C within soil aggregates, but the effects of different organic manures were distinct.

Abstract:Investigation of the influence of different tillage methods on soil water content and water use efficiency have important theoretical and practical significance for the utilization efficiency of natural precipitation and the increase of crop yield. The gravimetrie soil moisture that soil samples were stored in metal cans, and oven dried at 105℃ for 6 hours was applied to determine the soil water content of soil from different years, seasons, profiles, and freeze-thaw. The influence of different tillage methods on soil water content and water use efficiency was assessed. The results showed that soil water content of different tillage systems decreased with the increase of soil depth, and it was significant when the soil depth was under 40 cm. Moreover, soil water content of different tillage systems was influenced by the precipitation and changed with season. The seasonal freeze-thaw decreased the soil water content of different tillage systems, however, soil water content of spacing tillage was increased from 0.93% to 2.23% with comparison of other tillage systems. Meanwhile, soil water storage was increased firstly then decreased with change of seasons, and was higher in the beginning of crop growth than in the end of crop growth. Influence of different tillage systems was on water consumption and water use coefficient was not significant; however, spacing tillage enhanced water use efficiency significantly, and the correlation between yield and water use efficiency was significant (r=0.76^**). Spacing tillage is an effective tillage system to improve the soil structure, increase soil water content, and enhance water use efficiency. Therefore, this study will provide a theoretical basis for the application of the conservative tillage technology for deep loosening tillage in the Northeast rain farming area.

Abstract:In order to explore the effects of land use types with different slope aspects on soil properties, five land use types (different slope aspect) in Weibei highlands were selected to analyze the differences of soil physical, chemical and biological properties in different land use types. The results showed that:(1)Soil water content, soil total porosity, soil organic matter content, total nitrogen content, microbial biomass carbon and nitrogen content decreased with the increase of soil depth, soil bulk density was the opposite except soil pH and particle composition in different land use types. (2)In 0-30 cm soil layer, on the sunny slope, soil water content, clay content and pH were the highest, while silt and total nitrogen content were the lowest in farmland; sand and total nitrogen content were the highest, while clay content was the lowest in artificial grassland; soil total porosity, soil organic matter content, microbial biomass carbon and nitrogen content were the highest, while soil water content, soil bulk density and pH were the lowest in artificial forest; soil bulk density and silt content were the highest, while soil total porosity and sand content were the lowest in natural grassland; soil organic matter content, microbial biomass carbon and nitrogen content were the lowest in abandoned farmland. On the shady slope, soil water content, silt content and pH were the highest, while clay content and total nitrogen content were the lowest in farmland; soil bulk density, clay content and microbial biomass nitrogen content were the highest, while soil total porosity, silt, sand and soil organic matter content were the lowest in artificial grassland; soil organic matter content and microbial biomass carbon content were the highest in artificial forest; soil total porosity, sand and total nitrogen content were the highest, while soil bulk density and pH were the lowest in natural grassland; soil water content, microbial biomass carbon and nitrogen content were the lowest in abandoned farmland. (3)Among the 5 types of land use, soil bulk density, fine clay, coarse clay, fine silt, coarse sand, soil pH, soil organic matter content (except abandoned farmland) of sunny slope were higher than those of shady slope. Soil water content (except abandoned farmland and farmland), soil total porosity, the coarse silt, fine sand, soil texture coarsening degrees, soil total nitrogen content (except artificial grassland), soil microbial biomass carbon and nitrogen content of shady slope were higher than those of sunny slope.

Abstract:The field experiment has been conducted to investigate the effects of different tillage practices and straw treatments on dry matter accumulation, nitrogen accumulation, and water, nitrogen use efficiency of winter wheat in 2015-2017. The split-plot experiment design was adopted. The main plot was straw returning (S) and no straw returning (NS). The sub-plot was deep tillage (DT), rotation tillage (RT) and no tillage (NT). The results showed that, compared with NS treatment, S treatment significantly increased flag leaf SPAD, photosynthetic rate and aboveground biomass in mature stage of winter wheat, while the yield of winter wheat was not significantly increased. The yield of winter wheat was significantly influenced by tillage practices. Yield of RT was significantly higher than that of DT for 4.88% and 9.05% in 2015-2016 and 2016-2017 respectively, and it was significantly higher than that of NT for 3.64% in 2016-2017. Significant interaction existed between straw returning and tillage practices. Yield of S+RT was significantly higher than that of NS+DT for 8.68% and 16.98% in 2015-2016 and 2016-2017 respectively. Compared with NS treatment, S treatment significantly increased aboveground N accumulation and water use efficiency of winter wheat. RT treatment significantly increased water use efficiency, aboveground N accumulation, kernel N accumulation, nutritional organs N operation rate and N grain production efficiency. Water use efficiency of RT was significantly higher than that of NT for 8.45% and 8.92% in 2015-2016 and 2016-2017 respectively, and it was higher than that of DT for 5.24% in 2015-2016. The partial productivity of N fertilizer in RT was higher than in NT and DT for 3.68% and 9.16% respectively, and N grain production efficiency of RT was significantly higher than that of NT and DT for 10.60% and 4.78%. There was a small decline in SPAD after anthesis, higher photosynthesis rater in anthesis and mature stage of winter wheat existed in S+RT treatment, that yield, water use efficiency, N partial productivity were significantly higher than those of NS+DT and S+DT treatments for 12.58% and 8.53%, 7.95% and 4.11%, 19.79% and 11.44% respectively. Therefore, the treatment of straw returning with rotational tillage was suitable for Huang-Huai-Hai Plain as a water and N saving cultivation practice.

Abstract:In order to explore the reasonable ratio of topdressing gluten wheat with nitrogen fertilizer, the effect of basal nitrogen application rate, dressing rate at jointing stage and booting stage (10:0:0, 7:3:0, 7:2:1, 6:4:0, 6:2:2, 5:5:0 and 5:3:2) on the N accumulate and transfer and grain yield and quality of CA0547 (strong gluten wheat) were studied in the irrigated wheat field in central of Shanxi Province. The results showed:(1) Appropriate dressing N had a significant regulatory effect on accumulation and translocation of N and dry matter, yield and quality of CA0547. (2) Dressing nitrogen could significantly increase nitrogen content after jointing stage, N transfer amount pre-anthesis and N accumulation amount post-anthesis, promote accumulation of N in grain, increase dry matter transport pre-anthesis and dry matter accumulation post-anthesis, which provided a material basis for the increase of yield. (3) About 68.38%~75.18% of N in the grains came from nitrogen translocation pre-anthesis, and 55.12%~70.04% of yield came from dry matter accumulation post-anthesis. Dressing nitrogen increased yield by increasing the number of ears and per spike, and increased N absorption and production efficiency. (4) Dressing nitrogen could improve the contents of gliadin, gluten, protein and wet-gluten, improve the gluten index and starch content, improve glutenin/gliadin ratio and straight/branch ratio, and improve grain quality. Correlation analysis also showed that increase dry matter accumulation post- anthesis and pre-anthesis nitrogen translocation amount of vegetative organs could improve quality. (5) The effect of N application at jointing and booting stage was inferior to N application at jointing stage. Comprehensive analysis showed that N amount of 150 kg/hm², at nitrogen ratio of 6:4:0 (base fertilizer:jointing fertilizer:boosting fertilizer) could better coordinate the relationship between yield and quality.

Abstract:In order to get optimal fertilization model for cotton planting in saline-alkali soil, a field experiment was conducted in a moderate saline-alkali soil in Dongying, Shandong Province. Six fertilization treatments (including control without fertilization, conventional fertilization, optimized fertilization, one-time fertilization, chemical fertilizer reduction, chemical fertilizer reduction + organic fertilizer) were set up. The nutrient accumulation and yield of cotton were studied by sampling and analyzing the plant during the key growth periods. Results showed that compared with optimized fertilization treatment, dry matter yield and the nutrient contents of nitrogen and phosphorus in the organs for the one-time fertilization treatment were significantly increased. The total accumulations of nitrogen and phosphorus in the boll stage of one-time fertilization treatment were 23.39% and 13.97% higher than those of optimized fertilization treatment, respectively. Furthermore, these two increasing rates were 50.98% and 46.94% respectively compared with control. The treatment of chemical fertilizer reduction (N, P₂O₅, K₂O reduced 20%) + organic fertilizer had the highest cotton yield, which was 31.14% higher than control, 13.37% higher than conventional fertilization treatment, and the economic benefit was 1 925 Yuan/hm² higher than conventional fertilization. Cotton yield of one-time fertilization treatment was similar to that of custom fertilization treatment, and economic benefit was 279 Yuan/hm² higher than conventional fertilization Cotton yields were positively correlated with the contents of soil alkaline hydrolysable nitrogen and available phosphorus. In the moderate coastal saline soil, the chemical fertilizer reduction (N, P₂O₅, K₂O reduced 20%) + organic fertilizer and one-time fertilization measures would give the better performance in cost-saving and yield-increasing.

Abstract:Water resource deficiency and low nitrogen use efficiency are very common in Huang Huai-Hai Plain (HHP). In order to deal with these problems, the experiment, using SM15 as the tested winter wheat cultivar, with different water supplies and nitrogen fertilizer combinations (two types of fertilizers, two application rates, two water supply levels), was carried out in the lysimeters in 2015-2017. The photosynthetic characteristics of all the treatments showed the same variation pattern:the flag leaf photosynthetic rate, transpiration rate and leaf water use efficiency (LWUE) increased firstly and then decreased. The flag leaf photosynthetic rate of W1 water supply quantity of 500 mm was significantly higher than that of W2 (water supply quantily of 250 mm), and the flag leaf photosynthetic rate of 180 kg/hm² was significantly higher than that of nitrogen application of 90 kg/hm². Cormparing with the application of inorganic fertilizers, the application of organic fertilizer could ensure the higher growth rate of flag leaf photosynthesis. The grain yield and dry matter accumulation in the W1M1 (water supply quantity of 500 mm and application of organic manure with about 180 kg/hm² treatment) were significantly higher than those in other treatments in the two growing seasons. According to the photosynthetic characteristics and grain yields of winter wheat, the experiment areas with organic fertilizers got higher yield and the rate of increasing production than those with inorganic. W1M1 was the best treatment, which had the highest yield and better photosynthetic characteristics.

Abstract:As a result of the controlled release of nutrients, controlled release fertilizer (CRF), used once, can meet the nutrient demand of field crops for more than 4 months, which can realize the efficient use of fertilizer. Now it is applied successfully in field crops. For this reason, according to the law of tomato nutrient absorption in solar greenhouse, four kinds of different CRF treatments (A, B, C, D) were established through added different quantity of controlled release urea and potassium chloride into growth-bag substrate, the paper investigated the effects of different CRF treatments on the growth-bag substrate nutrient change, and the growth, yield and quality of tomato in solar greenhouse compared with no fertilizer (CK) and conventional fertilization (CKT). The experiment results showed that with the increase of CRF dosage, tomato plants growth and yield showed a change trend of first increase and then decrease. Among all treatments, the treatment C was the best, of which the substrate EC value was stable, the nutrient content of available nitrogen, phosphorus and potassium in growth-bag substrate of treatment C became slightly lower than that at the beginning; Compared with CK, the plant height increased by 21.75%, the stem width increased by 59.46%, the biomass accumulation increased by 75.12%, the yield increased by 226.36%, and the fruit quality was much improved. Compared with CKT, little nutrient was left in the substrate and the fruit yield increased by 24.48%. The experiment result indicates that CRF could increase the nutrient use efficiency and fruit yield for substrate growth-bag of tomato in solar greenhouse.

Abstract:In order to reveal the influence of irrigation methods and nitrogen fertilizer on characteristics of functional leaf's photosynthetic light response of direct-seeding rice in cold and black soil region, the test-pit experiments was carried out Two factors were set, including irrigation methods and nitrogen fertilizers. The characteristics of photosynthetic light curve of rice leaf with different water and nitrogen regulations in the tillering stage and the heading-and-flowering stage was studied by using comprehensive test design. The result showed that when nitrogen rate increased, photosynthetic light response curves of direct-seeding leaf rised, especially when the photosynthetic photon flux density was higher than 600 μmol/(m²·s). Parameters derived from non-rectangular hyperbola model indicated P_nmax (maximum photosynthesis rate), α (apparent quantum yield) and LSP (light saturation points) increased with the increase of the nitrogen rate, while LCP (light compensation points) reduced. P_nmax, α and LSP of controlled irrigation treatments were higher than those of flood irrigation treatments at the same nitrogen rate, while LCP was lower. In conclusion, higher nitrogen inputs, within the range of 0~135 kg/hm², and controlled irrigation method lead to the increase of photosynthetic capacity, enhancing the light use efficiency and the adaptability to both strong and weak light of rice leaf. These findings were helpful for improvement of photosynthetic light response curve and rice yield. It should be taken into full consideration for the effects different nitrogen levels and irrigation ways on leaf's photosynthetic light response curve in paddy of direct-seeding rice.

Abstract:The field experiment was carried out to study the effects of different growing stages and different gradient way of regulated deficit irrigation (RDI) on growth, photosynthetic characteristics, yield and quality in Isatis indigotica of the Hexi oasis. Field experiments were conducted from 2016 in the National Key Irrigation Experimental Station of Zhangye Water Resources Bureau in Central Hexi Corridor District, from numerous The Isatis indigotica seeds, bred by the Department of Chinese herbal medicine of Gansu Agricultural University, were used as tested materials. Two-factor randomized blocks were designed with nine treatments, including different growing periods and different gradient way of RDI. Each treatment had three plots as repeats in a completely random-sized design. In each growth period, the photosynthetic parameters of Isatis indigotica were determined, and after the harvest, yield and quality index were measured on fresh Radix Isatis. The results would provide a theoretical basis for reasonable planting and sustainable development of Isatis indigotica in Hexi oasis. The results showed that:(1) In the periods of vegetative stage and fleshy root growth, the water deficit significantly reduced the Isatis leaf net photosynthetic rate, transpiration rate and stomata conductance, and the declines increased with the raising water deficit regulation (WDR) level. (2) The highest yield was achieved under light WDR (7 342.05 kg/hm²) in the mature period of the regressed deficit, which was 5.32% lower than that of the full irrigation (P> 0.05). (3) The highest utilization efficiency of WDR (2.14 kg/m³), was followed by mild WDR in the flesh root maturity stage. (4) The quality of Isatis root was greatly improved especially in maturity period by mild WDR. The indigo, indirubin and (R,S)-goitrin content of Isatis root were improved by 0.09, 0.41 mg/kg and 0.007 8 mg/g,but content of polysaccharide reduced by 3.37 mg/g, respectively. Therefore, considering the yield, water use efficiency and quality, the fleshy root maturity could be implemented with RDI slightly, i.e., the relative water content of the soil was 60%~90% during this period, which could be used as the optimum way of cultivating irrigation.

Abstract:The combination of hyperspectral data and multi spectral image enables high-precision and large-area inversion of soil organic carbon content to be achieved. Taking the organic carbon content in 0-20 cm soil layer of Bao Dian mining area in Shandong Province as the study object, this study first applied the band averaging method to synthesize the hyperspectral narrow band into the wide band of GF-1 WFV, based on which the hyperspectral model of soil organic carbon content were established. Then the optimal hyperspectral model was corrected to the multispectral model through the ratio correction method, and the spatial distribution map of soil organic carbon content was obtained through decision tree classification. Finally, the distribution characteristics of soil organic carbon content were analyzed combined with the land use status map. The results showed:(1) The determination coefficient of the multi spectral model obtained by band fitting and ratio correction was 0.76, indicating that the soil organic carbon content could be retrieved steadily via the model. (2) The soil organic carbon content in the study area varied from 0.71 to 38.15 g/kg, with a mean value of 14.12 g/kg, which was at a medium level in general. The soil organic carbon content was mainly 11.60~17.40 g/kg, followed by 5.80~11.60 g/kg, occupying 48% and 29% respectively in the study area. (3) The soil organic carbon content of mining area, some roads and settlements was high. The soil organic carbon content of cultivated land was at medium level, and the content in woodland and grassland was relatively low. The content of organic carbon around the subsidence area was obviously lower than that in other land use types.

Abstract:The mixed applications of an eco-friendly soil absorbent polymer (SAP) and a compound microbial fertiliser (MF) in the aeolian sandy soil was studied for the improvement project of afforestation in Zhangbei County. The mixed applications with low, moderate or high SAP (20,40,60g/tree) and MF (150,300,450 g/tree) concentrations were used for the afforestation of Scots pine. Differences in field moisture capacities, available water contents, WSA percentages, microbial colony count and soil microbial biomass carbon/nitrogen (S_mbc/S_mbn) at different mixing ratios were analysed. The effects of SAP and MF on soil physical properties, soil microbes and survival rates of Scots pine were examined. The mixing ratio and amount applicable to afforestation in arid and semi-arid regions were explored. Results showed that SAP and MF could remarkably improve soil and increase survival rate, but the effects of the mixing ratio on these indicators varied with concentrations. When a single highly concentrated SAP was used, the field moisture capacity, available water content and WSA content were increased by 141%, 150% and 63.8% respectively compared with the control. The mixed application of moderate SAP concentration and MF significantly increased the microbial activity and microbial colony count. In particular, the microbial activity and microbial colony count of fungi/bacteria/actinomycetes increased by 77%, 108% and 93% compared with the control, respectively, and the S_mbc/S_mbn increased by 132%,178%. The application of SAP and MF significantly promoted plant growth. The plant height and basal diameter respectively increased by 6% and 12% compared with the control. The improvement of survival rate by single SAP was greater than that of the mixed application. The moderate SAP concentrations increased the survival rate of Scots pine. During afforestation in arid and semi-arid regions, the application of moderate SAP concentration mixed with MF could improve soil and increase survival rate of afforestation.

Abstract:The objectives of this study were to investigate the influences of different concentrations of zinc (Zn) application on cadmium (Cd) bioavailability in soil and Cd accumulation in rice grown in two Cd-polluted soils. Rice pot experiment was carried out and the rice variety was Weiyou 46. Application exogenous Cd and Zn,curing generated two Cd-polluted soil (0.72 and 5.26 mg/kg Cd) and four Zn-treated soil (0, 40, 80 and 160 mg/kg). Results showed that the application of Zn had an influence on the test indexes, while soil Cd concentration was the dominant factor affecting the soil Cd activity and the Cd accumulation in the rice plants. In the 0.72 mg/kg Cd treatment, the application of Zn reduced exchangeable Cd concentration in soil by 1.9%~17.0%, while increased the uptake and accumulation of Cd in the iron plaque, roots, and brown rice, the Cd concentration in brown rice was ranging from 0.09 to 0.17 mg/kg, furthermore, the Cd concentration in brown rice was linearly positively related to the exchangeable Zn concentration in soil. In the 5.26 mg/kg Cd treatment, the exchangeable Cd concentration in soil was increased by 2.1%~4.8%, the Cd concentration in various rice organs was decreased. Moreover, the Cd concentration in brown rice decreased to 0.12 mg/kg when the Zn concentration increased to 80 mg/kg, whereas it was 0.45 mg/kg at 0 mg/kg Zn, lower than the National Food Safety Standard of 0.2 mg/kg (GB 2762-2017). In addition, the correlations of the Cd concentration in brown rice and exchangeable Zn in soil were linear and negative. The experiment results also found that application of Zn increase the accumulation rate of Cd in the underground part of rice planed in two Cd-polluted soils, and then decreased the Cd accumulation rate of aerial part. A certain amount of Zn to reduce the Cd concentration in brown rice was feasible in the soil treated with 5.26 mg/kg Cd and the amount of Zn 80 mg/kg was the best applied in the experiment, while it increased the risk of Cd accumulation in the soil treated with 0.72 mg/kg.

Abstract:The effect of phosphate fertilization on the growth of Chlorophytum comosum and soil enzyme activities in Cd-contaminated soils were investigated. The results showed that C. comosum was able to grow well in Cd-contaminated soils contained 100 mg/kg Cd. The appropriate addition of P fertilization was capable of distinctly improving chlorophyll content, cell membrane permeability and antioxidase activities of C. comosum (p<0.01). The chlorophyll content, cell membrane permeability and antioxidase activities of C. comosum were promoted by low P level fertilization and inhibited by high P level fertilization. Both the chlorophyll content and the CAT activity increased to the maximum at 200 mg/kg of P. Election Conductivity and MDA content dropped to the minimum value at the same time. The POD activity started to rise when the P content were at 200 mg/kg. The results indicated that P addition could reduce the degree of damage to the cell membrane to the lowest level, and significantly enhance antioxidation. Simultaneously, the soil enzyme system in Cd-contaminated soils could also be improved by using phosphate fertilizer. The activities of catalase and urease were enhanced at low P content while they were decreased at high P content. The urease activity showed the opposite trend of the catalase and urease activities. The phosphatase activity was inhibited. Besides, the activities of catalase and urease were elevated to the maximum values while the sucrase activity was decreased to the minimum value at 200 mg/kg of P content. Moreover, the four soil enzyme were highly correlated with P concentration (p<0.05) and the correlation sequence of the four soil enzymes was urease > catalase > sucrose > phosphatase.

Abstract:Layered soil medium is a commonly existed soil layer structure. The accurate division of soil layers determines the accuracy of related researches on soil science. Therefore, it is of practical significance to study the techniques of fine soil layering. In order to classify the upper soil non-destructively in the field scale, the resistivity imaging technology was used. Based on the changes of the resistivity curve longitudinally, the stratification results were adopted to study the spatial variability of the soil resistivity. Results showed that:After finely classifying resistivity data using resistivity curve method, the result map could meet the need of visualization and fine expression in the research process. Using the Wenner quadrupole inversion resistivity curve method, the shallow soil in the research area were divided into four layers, including 5-13, 13-24, 24-50 and 50-70 cm, the prediction value and actual value were closest. I was found that the coefficient of variation of 5-13 cm (plough layer) was the highest (0.28) and the average resistivity value at 13-24 cm (plow bottom layer) was the lowest (17.35 Ω·m). The results conformed to the actual soil conditions in the test area, through this method, the soil condition could be obtained accurately, quickly and even non-destructively. The findings attained in this research provided technical support for the research on accurate agriculture and preferential flow of soil fracture.

Abstract:Based on the GF-1 satellite images, the study used five different methods including high-pass fusion, Ehlers transformation, Brovey transformation, Gram-Schmidt spectral sharpening, and principle components spectral sharpening to obtain an optimal method for image enhancement of production and construction projects. To access the performance of these fusion methods, the quality of the fused image was evaluated by the visual and statistical analyses. Moreover, the object-oriented classification method was used to examine the accuracy of extracting the disturbance information on production and construction projects in the central area. Results showed that the principle components and gram-schmidt fusion algorithm achieved better fusion of multispectral spectral information and panchromatic image spatial information, and therefore, higher spectral fidelity, richer spatial information and better visual effect were obtained. Quantitative analysis showed that the principle components transform preserved the spectral characteristics of the original multispectral image to the maximum extent. The gram-schmidt fusion algorithm had the advantage of gain, and the fused image had the largest amount of information and the most detailed texture. Overall, the principle components and Gram-Schmidt image fusion algorithms had great advantages in information extraction of disturbance information on production and construction projects. The extraction accuracy in the coal-covering area was 100%, and greater than 80% in the mixed area of bare land and construction land and the classification accuracy was 10% higher than that of the original multispectral image. This research provide a solid foundation for promoting the efficient application of domestic high-resolution remote sensing data in water and soil conservation regulation of production and construction projects, and is of great significance to advance the efficiency and informationization of soil and water conservation supervision on production and construction projects.

Abstract:Coal gangue is a potential resource. A large number of coal gangues not able to be disposed quickly due to the existing technical conditions occupied land and caused ecological environment problem, which has become a hot issue of ecological environment conservation in coal mining area. The vegetation restoration of coal gangue mountain is the best way for in-situ conservation and environmental protection. Humic acid (HA), as the main component of humus, has a positive effect on improving the unfavorable plant growth environment. To discuss the effects of HA on nutrient release from coal gangue, an experiment of incubator at constant temperature was conducted to study the characteristics of the pH and electrical conductivity (EC) of coal gangue and the release of alkali hydrolysable nitrogen (AN), available phosphorus (AP) and available potassium (AK) from gangues under different humic acid concentrations and incubation durations. Compared with treatment without HA (CK), the pH of coal gangue with HA increased significantly, the highest value reached 7.77, while the EC value decreased sharply, with an average of 126.13 μS/cm, dropped by 77.81% compared with the average EC value of CK. All the AP and AN of coal gangue added with HA increased greatly. The content of AP was 2.33 times that of CK, and the content of AN reached 1.94 times that of CK. The same is true of AK. The greater the concentration of humic acid added, the better the effect of promoting the release of nutrients from coal gangue. During the incubation, all the indicators for study presented a change characterized as "V" or "N", and in the later stage, the change gradually showed trend of stability. Coal gangue has a certain potential for nutrient supply, therefore, adding humic acid to coal gangue can improve the availability of plant nutrients.