Abstract:The spatial and temporal distribution of rainfall was an important factor influenced runoff and sediment yield. Based on the study about rainfall intensities and rainfall duration under the different moving rainfall directions, the relationship between runoff and sediment yield and its variation regularity was expected to be revealed. In this study, the indoor simulated moving rainfall experiments of 2 moving directions (up and down movement), 2 rainfall intensities (1.35 mm/min, 2.75 mm/min) and 2 rainfall durations (60 min, 120 min) were carried out in order to analyze the runoff and sediment characteristics under different moving rainfall directions, intensities and durations. The results showed as follows: (1)For the moving upstream rainfall, with the same rainfall duration (rainfall intensity), initial runoff time of heavy rain (long rainfall duration) was 140 s (240 s), 165 s (65 s) earlier than that of light rain (short rainfall duration). (2)For the moving downstream rainfall, the stronger rainfall intensity was and the shorter rainfall duration was, the steeper runoff and sediment yield curve was. The time of runoff and sediment arrived peak value was identical. (3)Compared with the moving upstream rainfall, the average time of initial rainfall runoff, runoff and sediment reached the peak lagged 2 210 s, 2 468 s, 2 948 s, respectively, in the moving downstream rainfall. The total of runoff and sediment yield reduced by 13.08%~74.90% and 42.95%~84.24%, respectively, but the peak value of runoff and sediment were not obvious change rules. (4)The function expressions of cumulative runoff and sediment yield were different under different moving rainfall directions.

Abstract:Rainfall characteristics and the effects of different types of rainfall on runoff and sediment of typical plant measures in rocky mountain areas of Taihang were studied based on the observation of rainfall, runoff and sediment of a standard runoff plots and four plant measures runoff plots nearly five years (2006—2010) in Baima small watershed Changzhi city, Shanxi Province. The results showed that: 1)Erosive rainfall mainly concentrated in May to August in rocky mountain areas of Taihang. The number of erosive rainfall accounted for 54.55% of the total number of erosive rainfall in July and August, the precipitation of erosive rainfall accounted for 61.19% of the total precipitation of erosive rainfall, so the period was the key to the prevention and control of soil and water loss; 2)Runoff (R) and precipitation (P), maximum 30 min rainfall intensity (I30), the product of precipitation and maximum 30 min rainfall intensity (PI30) had positive correlation and significant at the 0.01 level; Erosion (E) and maximum 30 min rainfall intensity (I30), runoff (R), the product of precipitation and maximum 30 min rainfall intensity (PI30) had positive correlation and significant at the 0.01 level. 3)Under the condition of different types of rainfall, the runoff reduction benefits of 4 kinds of typical plant measures between 17.18%~91.86%, difference was obvious; Under the condition of B type rainfall, the runoff reduction benefits of 4 kinds of typical plant measures was the lowest, arbor was 43.38%, shrubs was 24.44%, artificial grass was 26.59%, natural slope was 17.18%; Under the condition of E type rainfall, the runoff reduction benefits of 4 kinds of typical plant measures was the largest, arbor was 89.29%, shrubs was 91.86%, artificial grass was 75.56%, natural slope was 66.22%; 4)Under the condition of different types of rainfall, the sediment reduction benefits were: arbor>shrub>artificial grass>natural slope; The influence of the largest precipitation of A type rainfall and the biggest maximum 30 min rainfall intensity of B type rainfall on the sediment reduction benefits of plant measures was remarkable. In conclusion, under the condition of different types of rainfall, the runoff and sediment reduction benefits of 4 kinds of plant measures was obvious; Plant measures could effectively control soil and water loss in the region.

Abstract:To master the law of slope erosion in the hilly area of center southern of Shandong province and provide a theoretical basis for the prevention and control of water and soil loss in the area, this study took Yaoxiang small watershed in Tai'an as the research object, and explored the difference of runoff and sediment between different runoff plots with different measures and critical rainfall to cause runoff based on rainfall, runoff and sediment data of 4 runoff plots. The study also explored the relationship between runoff and sediment and rainfall using the correlation analysis method. The results were as follows: (1)The critical rainfall to cause runoff showed that bare land

Abstract:The Hulunbair sandy grassland was used as the research object, and studied the effects of different grazing systems on phosphorus characteristic and phosphorus loss in surface runoff in arid and semi-arid grassland. We simulated rainfall with different intensities to study phosphorus concentration changing of surface runoff under three types of grazing systems such as no grazing, rotation grazing and free grazing. The effective mixing depth model was used to simulate the process of phosphorus loss from soil. Conclusions were as follows: Under different rainfall intensities, phosphorus runoff loss of free grazing system was the highest; its phosphorus loss was 1.31 to 1.5 times for no grazing grassland and 1.59 to 1.74 times for rotation grazing grassland. Particulate phosphorus was the major form phosphorus in the runoff and its content was 2.2 to 3.7 times higher than dissolved phosphorus. According to the result of experimental data fitting, the incomplete mixing model was better than the complete mixing model, and the model could simulate accurately for the case of higher rainfall intensity. The different grazing systems had significant influences on phosphorus losses in runoff under the rainfall intensity less than 1.5 mm/min. The phosphorus losses in rotation grazing grassland were the lowest. So, if we gently changed the grazing systems from the free grazing to no grazing and rotation grazing, the phosphorus loss situation would be decreased, which also would be helped for ecologically sustainable development in grassland.

Abstract:Under the conditions of three different types humic acid on erosion and nutrient loss on loess slope experiment above the same amount of 18 L/min in the Chinese academy of sciences agricultural ecological experimental station of the loess plateau, analyzed the impact of different types humic acid (NHA, FA and BFA) and humic acid in different amount on soil erosion and nutrient loss. Results showed that the different amount of NHA treatment, runoff increased with time. Compared with the slope runoff of 500 g/㎡, NHA content of 150 g/㎡ and 300 g/㎡was 1.14 times, 1.08 times respectively. Sand content and concentration of Br- both decreased with the increase of time, cumulative runoff, sediment accumulation, the cumulative loss both decreased with the increase of dosage, slope cumulative runoff of 150 g/㎡, 300 g/㎡was 2.16 times, 1.87 times as much as 500 g/㎡, Br- cumulative loss was 1.38 times,1.23 times as much as 500 g/㎡. Dosage of 500 g/㎡ NHA to prevent soil erosion and nutrient loss was the best. Under different concentrations of FA, runoff increased with time, the cumulative runoff of concentration of 0.1%，0.03% was 1.19 times，1.33 times of 0.05% concentration, Br- concentration and rate of sand containing substantially reduced with increasing time, cumulative runoff, accumulated sediment and cumulative loss decreased firstly and then increased with increasing concentration, the sediment loss of the concentration of 0.1%, 0.03% was 3.03 times, 4.09 times as much as 0.05%, cumulative Br- loss was 1.1 times，1.26 times to the total loss of 0.05%Br-, and the effect of 0.5% FA concentration on soil erosion and nutrient loss was the best. Under different concentrations of BFA, runoff increased with time, slope cumulative runoff of BFA concentration of 0.1%, 0.05% was 1.15 times, 1.1times as much as 0.03%, sandy rate and Br- concentration decreased with increasing time. Cumulative runoff, sediment accumulation increased with the increase of the concentration,?however, cumulative runoff increased firstly and then decreased with the increase of concentration, the cumulative sediment of concentration of 0.1%, 0.05% was 1.36 times, 0.49 times as much as 0.03%. The total loss of 0.01%Br- and 0.03% Br-was 4.06 times, 3.5 times as much as 0.05%Br-, and the effect of 0.5% BFA concentration on soil erosion and nutrient loss was the best. Comprehensive consideration of the effect of three different types of humic acid to prevent erosion and nutrient loss on the slope was BFA>FA>NHA.

Abstract:To effectively control soil erosion and non-point source pollution of slope-farmland in purple hilly, the paper mainly studied the effect of different conservation measures on runoff, sediment and nutrient loss at natural rainfall conditions and crop yield of slope farmland by runoff plots location observation method, which deeply revealed the effect of biological carbon, poly propylene amide and straw mulching measures on controlling soil nutrient loss from slope farmland. Results indicated that: (1)Compared with the background value, the increase of soil nutrient content showed as SM (straw mulching)>PAM (polyacrylamide)>BC (biological carbon), which indicated that the corn straw mulching measures could improve soil nutrient best, followed by polyacrylamide. (2)The effects of different soil management measures to control the runoff and sediment yield changed in order as SM>PAM>BC. Measures of BC, PAM, SM could reduce runoff 0.00%-54.55%, 0.00%~85.79%, 0.00%~92.39%, respectively, and the amount of sediment yield decreased by 2.67%~47.78%, 5.87%~77.90%, 11.47%~90.17%. In the medium and heavy rain, the effect of protective measures on reducing runoff and sediment was significant, but it was waked in rainstorm. (3)The effect of soil management measures on controlling nitrogen loss was in order as SM>PAM>BC. Compared with CK, under medium and heavy rain conditions, the total nitrogen loss of protection measures was reduced by 16.24%~76.29%, and hydrolytic nitrogen loss was reduced by 6.21%~81.93%; under the rainstorm condition, nitrogen loss was reduced by （-11.74%）~11.99%; hydrolytic nitrogen loss was reduced by （-9.87%）~17.39%. The results showed that corn straw mulching was the best method to control nitrogen loss. (4)The effect of different soil management measures on controlling the phosphorus loss was different. Protective measures of BC, PAM and SM under middle and heavy rain conditions could control total phosphorus loss effectively (15.00%~81.44%), and the effect weakened ((-6.68%)~10.98%) under rainstorm condition. Compared with CK, the effect of protection measures on increasing corn grain yield was in order as SM (29.43%)>PAM (19.01%)>BC (12.66%). The soil management measures of biological carbon, polyacrylamide and straw mulching controlled soil nutrient loss from slope farmland effectively, and straw mulching measure controlled the best.

Abstract:In order to determine the effects of red soil aggregate in different particle-size (<0.25, 0.25～0.5, 0.5～1, 1～2, 2～5 mm) on splash erosion, a simulated rainfall experiment (75 mm/h rain rate and 45 min rain time) was conducted. Aggregate breakdown, splash rates change, net splashed particles and splash spatial distribution were chosen to analyze the splash regulation. The results showed that: (1)2～5 mm aggregate breakdown rate was as high as 96.06%, while <2 mm was less than 50.00%. The index of breakdown rate significantly decreased with the aggregate size increasing. (2)The splash rates of <0.25 mm aggregate skyrocketed at first, and soon collapsed to 0.08 g/min. This phenomenon, in this period, might attributed to soil crust, which was developed rapidly and completely; The splash rates of 0.25～0.5 mm aggregate, which could be clearly observed to become muddy after 18 min rainfall, also skyrocketed at first, but then decreased slowly. The splash rates of 0.5～5 mm aggregate kept a long time increase and also decreased slowly after 36～42 min. (3)There were the same trends for the quantity of total splashed particles, in upslope and downslope area, net splashed particles among different size of aggregate. Splash erosion quantity within 0.25～0.5 mm was the maximum, and then gradually reduced with the particle size increasing. (4)Almost all of splashed aggregates spread in the scope of 60 cm, and the mean weight distance (MWS) of small aggregate was larger than those of the bigger one. This study provided a new approach to reveal the rainfall splash erosion mechanism of red soil, which had great significant for perfection of the physical progress model of rainfall erosion.

Abstract:The characteristics of runoff and nitrogen loss in sloping cropland of purple soil during corn growth stages were carried out to provide a theoretical basis for the prediction and effective prevent of nitrogen loss in sloping cropland. Simulated rainfall combined with runoff plot experiments (1 m×2 m) was employed during each corn growth stage, including seedling stage, elongation stage, tasseling stage and maturity stage. The rainfall intensities were set as 1.0 mm/min, 1.5 mm/min and 2.0 mm/min. The results indicated that the runoff in soil surface and nitrogen loss increased with the increasing rainfall intensity during corn growth stages. Total runoff in the seedling stage was significantly higher than that in other growth stages. The average concentration of nitrogen loss in the elongation stage was up to 16.36 mg/L. The average amounts of nitrogen loss obtained the maximum value of 10.24 mg/m2 at the seedling stage, and the minimum value of 2.97 mg/m2 at the tasseling stage. For the nitrogen forms, ammonium nitrogen and nitratenitrogen accounted the greatest part of nitrogen loss at seedling stage and maturity stage of corn, respectively, and the loss of ammonium nitrogen and nitratenitrogen was the least at the tasseling stage of corn. During the whole growth stages of corn, nitratenitrogen was the main nitrogen form in the runoff of surface soil and accounted 77.98%~97.85% of the total nitrogen loss. The concentration of nitrogen loss was the highest in the elongation stage, and the nitrogen loss amount was the greatest in the elongation stage of corn. Nitrogen loss in the seeding and elongation stage of corn could easily lead to the eutrophication in waters. Thus, it was necessary to cut the application of base fertilizer and top dressing of nitrogen, and increase vegetation cover to reduce nitrogen loss in runoff.

Abstract:This paper took the soil characteristics between preferential flow and matrix of natural secondary forests at eastern mountainous region in Heilongjiang province as research object. By using the field dye tracer method and Image processing software .The results showed that: The phenomenon of soil preferential flow was very obviously in natural secondary forests at eastern mountain in Heilongjiang province. There were mainly macro pore flow, mean flow and pipe flow. The soil pore connectivity was unimpeded in surface. Water movement process became relatively uniform. So the preferential flow was not easy to occur. Within the range of 10—45 cm soil layer, the dyeing path was no longer a whole uniform diffusion. There was obviously preferential migration and certain surround characteristics. From surface to bottom of soil, the non-capillary porosity of staining region was 0.3%~2% higher than unstained area. Meanwhile, non-capillary porosity was considered as main reason for the generation of preferential flow. In the range of 0—40 cm soil layer, the water holding capacity, capillary capacity and field capacity in the dyeing area were higher than those of unstained area, the soil bulk density was on the contrary. The priority path was most obviously in 20—40 cm of soil in natural secondary forest. In this area, the infiltration rate of preferential flow area was significantly higher than that of matrix. And it proved that the difference of soil characteristic was the main reason of soil preferential flow of natural secondary forest at eastern mountain in Heilongjiang province.

Abstract:Effects of root system on soil fixation could reduce nutrient loss from the slope land. Assessment of root systems on soil nutrient loss in runoff under different cropping patterns could be used to evaluate different crops’ effect on soil and water conservation. This paper took the main crops, corn and potato, in Yunnan province as case study, the erosive events, runoff yield, soil loss, and nutrient loss in runoff during crop growth season under different cropping patterns as well as root characteristics of maize monoculture, potato monoculture and maize and potato intercropping were determined. Results showed that compared with monoculture, intercropping pattern could significantly decrease water and soil erosion under conventional management. The erosive events under maize-potato intercropping were 4 and 2 times less than those under potato monoculture and maize monoculture, respectively. In the flowering period, the runoff yield from intercropping reduced by 20.49% and 27.15%, compared with potato monoculture and maize monoculture, respectively. During mature period, intercropping reduced soil loss by 49.67% and 40.31% compared with potato and maize monocultures, respectively. Meanwhile, total phosphorusloss in runoff under intercropping pattern was smallest, which reduced by 78.06% and 73.98%, respectively compared with potato monoculture and maize monoculture. There was a significant difference (P<0.05) in maize and potato intercropping and monocultures in terms of root length, root surface area and root volume during mature period. Compared with potato and maize monocultures, root length with intercropping increased by 80.06% and 73.54%, respectively. The root length, root surface area and root volume of intercropping negatively correlated with total nitrogen loss in runoff, which indicated that intercropping had better root system and thus better control on nutrient loss.

Abstract:In order to understand the effects of different vegetation types and coverage on the ways of nutrient loss of gravel soil slope, the characteristics of nitrogen and phosphorus loss through surface runoff, interflow and erosion under six different vegetation patterns were studied by the method of simulating runoff plots rainfall. The results showed that nitrogen loss of vegetation patterns reduced 0.91~4.60 times than bare slope, while phosphorus loss reduced 6.25~63.9 times, and nutrient control effect on slopes with different vegetation listed as follows: Shrub-grass slope>herb slope>shrub slope>bare slope. There was remarkable difference nitrogen and phosphorus loss characteristics through surface runoff, interflow and erosion of six different vegetation patterns. The main way of nitrogen and phosphorus loss in bare slope was eroded sediment, the main way of shrub slope was surface runoff, however, herb slope and shrub-grass slope was surface runoff and interflow. The main way of phosphorus loss in slope of herb, shrub and shrub-grass was eroded sediment and surface runoff. Vegetation coverage measures had a significant interception in the nitrogen and phosphorus loss on the bare slope of gravel soil. The main loss way of nitrogen and phosphorus transformed erosion sediment to non-erosion sediment essentially. Shrub coverage had a significant positive correlation with nitrogen and phosphorus runoff loss by surface runoff, and had a significant negative correlation with nitrogen and phosphorus loss by interflow.

Abstract:In order to reveal the influences on the runoff producing and sediment on the hillslope which were exerted by different tillage measures in Karst region, the researchers used independent designed soil storehouse and indoor simulated rainfall measures, set particular rainfall intensity to study the features of runoff and the soil loss of the naked slope farmland in Karst region. The results showed: When the rainfall intensity was 63 mm/h and the declivity was less than 10°, ploughing measures could decrease the time of runoff producing of underground pores, and no-till could slow down its runoff producing, and its sediment yield was 66% of no-till. Otherwise, it conversed when the declivity was greater than 10°, and the sediment yield of ploughing were 16% and 6% of no-till separately. When the rainfall intensity was 100 mm/h and the declivity was less than 10°, the ploughing measures could speed up the confluence process of surface runoff on slopes, and the sediment yield of no-till was 41% of ploughing. Otherwise, it conversed when the declivity was greater than 10°, and the sediment yield of ploughing were 68% and 0.9% of no-till separately. In the circumstance of the same declivity and rainfall intensity, ploughing measures could decrease the loss of soil with surface runoff.

Abstract:The collapsing hill was a specific form of soil erosion in the granite red soil region of Southern China．It was one of the most important indications of serious soil erosion.As the material source of collapsing hill, the collapse of collapsing walls was the most active part of collapsing erosion. The soil disintegrating characteristics was an important indicator of the collapsing hill in southern China，and also the critical basis for soil conservation．In this paper, we used a combination of plot-based detailed representation and laboratory experiment based on broad field investigation to study the disintegration characteristics and the influence factors on different layers of collapsing wall. The results showed that: (1)The soil physico-chemical properties of the soil collapsing wall layer were closely related to the weathered degree of weathering mantle, and it showed some regularity. (2)At different levels of the initial soil moisture content, the order of the disintegration speedwas as the following：red soil layer

Abstract:In order to determine the index of soil shearing strength, soil moisture content, bulk density, dry density, total porosity, organic matter and soil aggregate MWD value (which containing dry and wet screening), five types of land use, including conifer and broad-leaved mixed forest, shrub forest, field, sloping farmland and wasteland, had been taken into consideration and the field survey and laboratory experiment under different grades (10°, 15°and 20°) were conducted, besides, the fuzzy close-degree analysis and stepwise regression analysis had both been used, for analyzing the influencing factors on soil shearing strength under those land use types. The results showed that in the same land use type, soil cohesion force increased firstly then decreased with slope degree increasing gradually. In conifer and broad-leaved mixed forest, the close degree was greatest between wet-screening MWD value and soil cohesion force, but this degree was comparatively greater between bulk density, dry density and this force in shrub forest, field and sloping farmland, in wasteland, this force was affected mostly by the organic matter. In conifer and broad-leaved mixed forest, shrub forest and wasteland, the calculating results of 4 kinds of close degrees showed that the main impacting factor on soil internal friction angle was total porosity, while in other two land use types, the main factors were bulk density and dry density. In conifer and broad-leaved mixed forest, the equations of soil shear strength based on dry density and bulk density were established (R2=0.865). In sloping farmland, the predicting model, which was based on dry density, bulk density and dry-screening MWD value, was established (R2=0.964). In shrub forest, field and wasteland, the factors affecting soil shear strength were dry density, dry-screening MWD value and bulk density.

Abstract:Aimed to reveal the mechanics of the soil reinforcement by root on the hedge of the sloping cultivated lands of purple soils in the Three Gorges Reservoir region, chosen three herbage hedge plants as the objects of this study. The root distribution and tensile strength of the three herbage hedge plants in the Three Gorges Reservoir region were compared. The results showed that the root biomass of Medicago sativa, Eulaliopsis binata and Pennisetum americanum × P. purpureum were （79.37±1.26）g/m2,（97.99±1.66）g/m2 and（71.76±1.96）g/m2, respectively. And the main root of Medicago sativa distributed in the 0 to 10 cm soil depth, the main root of Eulaliopsis binata distributed in the 10 to 20 cm soil depth and the main root of Pennisetum americanum × P. purpureum distributed deeper, in the 20 to 30 cm soil depth. The order of the average tensile resistance of the three herbage root were: Pennisetum americanum × P. purpureum (7.93 N)>Eulaliopsis binata (6.03 N)>Medicago sativa (5.40 N). There existed the power function relationship between the tensile resistance and root diameter, and there existed the highest correlation of Eulaliopsis binata roots. Meanwhile, the order of the tensile strength of the three herbage root were: Eulaliopsis binata (45.91 MPa)>Medicago sativa (19.68 MPa)> Pennisetum americanum × P. purpureum (15.28 MPa). There exited obviously significant difference of the tensile resistance and tensile strength among the three herbages roots（P<0.05）. The order of the soil anti-scouribility of the three herbage hedges were Eulaliopsis binata (85.28 L/(min·g))>Medicago sativa (69.47 L/(min·g))>Pennisetum americanum × P. purpureum (60.86 L/(min·g)), and there existed obviously significant difference among the soil anti-scouribility of the herbage hedges (P<0.05). While the value of the soil shear strength had the similar order, however, there did not existed obviously significant difference among the soil shear strength of the herbage hedges (P>0.05). The results showed that the Eulaliopsis binata hedge had the better soil reinforcement and soil conservation in this region. And the herbage reinforced the hedges was a new idea for the sloping cultivated lands harnessing in the Three Gorges Reservoir region.

Abstract:A precisely quantitative description of critical hydrodynamic characteristics of soil detachments was a important for developing physically based soil erosion model. In this study, the critical hydrodynamic characteristics of soil detachment on yellow soil slope were measured under different antecedent soil moisture contents（5%～23%）and slope gradients (1°～10°), the impacts of soil moisture content (3%～23%) on shear strength were also investigated. The study comprehensively analyzed the effects of different antecedent soil moisture contents, slope gradients and soil shear strengths on critical hydrodynamic characteristics. And the results showed that critical flow rate had power function relationship with slope gradient and antecedent soil moisture content. In this paper, an accurate equation was proposed, which reflected combined effect between the antecedent soil moisture content and slope gradient on critical hydraulic characteristics. A simplified power function could be used when the slope gradient was smaller than 5°. This equation could ignore the impact of the antecedent soil moisture content. Soil cohesion reached peak firstly and then fell down to stable with the increase of the antecedent soil moisture content. While the critical hydrodynamic characteristics of soil detachment showed a gradually decreasing trend.

Abstract:In order to reveal the influence of anti-erodibility in the cultivated land after returning farmland to forest, based on the field investigation and lab analysis, purple soil samples of 6-year Eucalyptus grandis plantations including pure Eucalyptus grandis, Eucalyptus grandis+grain crops, Eucalyptus grandis+fruits and farmlands were chosen as researching materials, the main physical and chemical indexes of soil anti-erodibility were analyzed by using principal component analysis method. Further, the coupling model of soil physical and chemical properties index and anti-erodibility index was built up by grey relational degree, and the corrosion resistance of different Eucalyptus grandis plantations was synthetically determined. The results showed that the main factors affecting soil anti-erodibility were >0.25 mm aggregate content, bulk density, organic matter, mean weight diameter, water stability index, available potassium and alkaline hydrolysis nitrogen, and >0.25 mm aggregate content was the most important factor to determine the level of soil anti-erodibility. There was a medium correlation between mean weight diameter and soil physical and chemical property indexes, there was a strong correlation between water stability index and soil physical and chemical property indexes. Effects of soil physical and chemical properties on soil anti-erodibility was followed by >0.25mm aggregate content>alkaline hydrolysis nitrogen>available phosphorus>organic matter>available potassium>bulk density. The system's overall level of coupling between soil anti-erodibility and soil physical and chemical properties was weak coordination. On a smaller scale, the coordination degree of system coupling was pure Eucalyptus grandis (moderate coordination)>farmlands (weak coordination)>Eucalyptus grandis+grain crops (mild incoordination)>Eucalyptus grandis+fruits (mild incoordination). Above all, the research conclusions could provide some theoretical basis for the evaluation of soil anti-erodibility in the cultivated land after returning farmland to Eucalyptus grandis plantations.

Abstract:Dye tracing method was used to observe the occurrence of preferential flow region under three kinds of land use patterns in Wangjiaqiao watershed in the Three Gorges Reservoir Area. Characteristics of preferential flow were obtained by figuring out the feature parameters of preferential flow. The results showed that the average volume content of rock fragment in different land use patterns was determined as follow: Garden land＞forest land＞farmland. The mean radius of soil macropores decreased with a increase of soil depth. The maximum preferential flow depth of forest land was up to 60 cm and the dying zone was distinctly irregular. In the farmland, the dying zone mainly distributed in 0-15 cm soil depth and the dying area was smaller than forest land. There existed a large portion of bypassing flow in the farmland. The dying area of garden land occupied a large part of soil profile and the connectivity of preferential pathway was good. The number of staining pathway was determined as follow: Garden land＞forest land＞farmland. It demonstrated the higher preferential flow dyed pattern differentiation degree was observed in the garden land. The staining pathway of subsurface flow in purple soil was largely consisted of ＜20 mm staining pathway width. The type of subsurface flow was mainly low interaction macropores flow. The process of soil water movement was influenced by both rock fragment and soil macropores.

Abstract:This article mainly targets on the investigated engineering spoils were typical of those placed during urban construction activities in Chongqing. Studied on physical and mechanical properties and infiltration characteristics of engineering accumulation body slope and determined the dangerous slip surface and safety factor of the slope of the engineering accumulation. The sampling points were arranged in the slope, the middle and the bottom and soil physical and mechanical properties were analyzed by collecting soil samples of the engineering accumulation, the infiltration process was studied by using the field double ring infiltration method, and the stability of the slope was analyzed by GEO-SLOPE software. The results showed as follows：(1)The grain size distribution of the engineering accumulation was not uniform, and the content of <2 mm particle size increased with the stacking time. The fractal dimension of each engineering accumulation varied from 2.04 to 2.47, and it showed up-slope>middle-slope>down-slope. (2) The saturated-water content of the engineering accumulation body gradually increases with the descending of the slope position; Infiltration rate with time showed three stages (rapid reduction, slow reduction, stable infiltration). The stable infiltration rates of the 2-month engineering accumulation (2 m), 2-year engineering accumulation (2 a) and 4-year engineering accumulation (4 a) were 4.53 mm/min, 3.17 mm/min and 7.02 mm/min, respectively. (3) The relationship between the shearing force and the shear displacement of the engineering accumulation in different stacking time is hardened; the cohesion values and internal frictional angles of all of the engineering accumulation were 16.43kPa ~31.88kPa and 2.23°~41.69°. The safety factors of the critical slip surfaces of the slopes underlain by the various engineering spoils were greater than 1.5, and the stability order is 2 years >2 months >4 years, the safety factor of the most dangerous sliding surface were 1.77, 2.23 and 1.66. By comparison, stacking 2 years of engineering accumulation body stability is the best, stacked in February of the second, stacked 4 years of accumulation of the worst stability.

Abstract:This study was aimed to determine the effects of forest types on characteristic of rainfall partitioning and its key factors. The yield of throughfall, stemflow in two forest types (secondary forest of Castanopsis carlesii and Chinese fir plantation) were measured based on field survey in Sanming, Fujian. We selected 3 sample plots (20 m× 20 m) in each forest, and the yield of throughfall and stemflow was measured in the field after each rainfall. Our results indicated that the annual precipitation was 1 706.6 mm, and there was no significantly difference between the yield of throughfall in secondary forest (1 204.0 mm, 70.6% of gross precipitation) and Chinese fir plantation (1 289.9 mm, 75.6% of gross precipitation). The yield of stemflow in secondary forest (4.8% of gross precipitation) was significantly higher than that in Chinese fir plantation (2.7% of gross precipitation). The canopy interception rate was 24.7% and 21.8% of gross precipitation in secondary forest and Chinese fir plantation, respectively. In addition, the yield of throughfall was negative correlated to the canopy density and leaf area index (LAI), suggesting the forest with higher canopy density and LAI lead to low throughfall yield. These results indicated that the differential of rainfall partition in secondary forest and Chinese fir plantation were influenced by the different canopy openness and tree bark structure of the two forests, thus tree species could significant alter the patterns of rainfall partitioning.

Abstract:It was vital to determine 18O value of evapotranspiration components and partition evapotranspiration (ET) into evaporation (E) and transpiration (T) of Platycladus orientalis forest in Beijing mountains area, it could provide important basis for the research of water-vapor exchange through the whole soil-plant-atmosphere continuum of regional area. 18O of atmospheric water vapor was obtained by a continuously water isotope analyze system, at the same time, branch and soil samples were collected and 18O of all samples were determined using a liquid isotope analyzer. Furthermore, we could estimate the oxygen isotopic composition of evapotranspiration vapor (δET) by a Keeling plot, and the oxygen isotopic composition of soil water vapor (δE) and transpiration vapor (δT) were determined by Craig-Gordon equation and the assumption of transpiration vapor had the same isotopic composition as stem water ( V= X), respectively. After obtaining these parameters, we calculated the contribution of transpiration to total evapotranspiration. The results showed that: (1)δE ranged between -20.26‰ and -17.48‰ during the four experimental days, S> V> E. It was concluded that δE depleted markedly in the process of evaporation. (2)δT increased from -7.31‰ to -2.09‰ during the four experimental days, and δET decreased from -3.84‰ to -8.21‰, which was calculated by Keeling plots and regression analysis showed that R2 for all experimental days were higher than 0.89, and E ET X. It showed that in the middle of the day at noon (we chose 12:00～14:00 as our sampling time), steady-state O18 isotopic composition could be satisfied. (3)The result of evapotranspiration partition demonstrated that the percent contribution of transpiration to total evapotranspiration ranged between 85.37% and 93.04%, the research results revealed that transpiration was the main component of total evapotranspiration, and water consumption of tree transpiration was much larger than that of soil evaporation.

Abstract:Chinese fir (Cunninghamia lanceolata) was the main tree species in afforestation in southern China. Evaluating the ability of carbon sequestration and conservation of water and soil of Chinese fir with different regeneration patterns was very important for scientific evaluation of forest ecosystem functions. Combining the field plot survey and laboratory chemical analysis method, Chinese fir seedling forest and sprout forest in southwest of Jiangxi were studied to reveal the carbon storage allocation characters of different stand ages and regeneration pattern, and to provide a scientific basis for the sustainable management of plantations. Our results showed that the carbon storage in tree layer of seedling plantation within different stand ages was generally higher than that of sprout forest. The carbon storage in tree layer of Chinese fir seedling forest within young, mid-mature, nearly mature, mature forest were 9.63 t/hm2, 42.14 t/hm2, 69.15 t/hm2 and 105.21 t/hm2, respectively, and the average annual amount of carbon sequestration were 1.69 t/hm2, 2.63 t/hm2, 3.01 t/hm2 and 3.39 t/hm2, and the trunk carbon storage of those accounted for 50.36%, 70.60%, 73.86% and 77.58% of the whole tree layer. The carbon storage in tree layer of Chinese fir sprout forest within young, mid-maturation, nearly mature, mature forest were 8.42 t/hm2, 23.58 t/hm2, 48.54 t/hm2, and 75.26 t/hm2, respectively, the annual average amount of carbon storage of those were 1.21 t/hm2, 1.57 t/hm2, 2.11 t/hm2 and 2.59 t/hm2, and the trunk carbon storage of those accounted for 54.28%, 66.12%, 71.92% and 73.70% of the whole tree layer. The lowest soil carbon sequestration of both Chinese fir seedling forest and sprout forest were found in young forest, and the highest of those were found in mature forest. The ranking order of soil carbon storage of Chinese fir seedling forest were mature forest (153.21 t/hm2)>nearly mature forest (138.17 t/hm2)＞young forest (128.30 t/hm2)>mid-maturation forest (113.11 t/hm2), while that of sprout forest were mature forest (154.03 t/hm2)>nearly mature forest (138.28 t/hm2)＞young forest (130.20 t/hm2)>mid-maturation forest (117.05 t/hm2). Under the condition of the same stand density, the total carbon storage of sprout forest was lower than that of seedling forest except for young forest. There were significant difference of carbon storage within different stand ages between Chinese fir seedling forest and sprout forest (P<0.05), however, the total carbon storage was not significantly different between the young and mid-mature forest, while significant difference was found between nearly and mature forest. Different growth rules and management caused different carbon storage allocation characters between Chinese fir seedling forest and sprout forest. In general, Chinese fir sprout forest were rich in understory species, and the ability for carbon sequestration of shrub, herb and litter layer were stronger, which were better than Chinese fir seedling forest in the aspect of soil and water conservation function.

Abstract:To explore the various degree water input influence on soil respiration in subtropical monsoon climate region, selected mixed broadleaf-conifer forest of Chongqing Jinyun Mountain Nature Reserves as the research object in 2014. The artificial blocking and increasing water were used to simulate different precipitation input, and then to analyze the impact (including 70% of saturated soil water content (addition 70%: 70%A), 100% (addition 100%: 100%A), 130% (addition 130%: 130%A), comparison (CK) and no precipitation (Z)). The result shows that: (1)All the diurnal changes of soil respiration formed a curve under the different water inputs, and it reached the maximum value during 12:00 to 14:00; and the same as monthly variation, it reached the maximum value in August and the minimum value in December; (2)Properly increased water could improve the Pearson correlation between soil respiration rate and soil temperature of 10 cm soil depth, but the best fitting of exponential model was comparison group. Reducing water and excessive increase water would reduce its correlation; the same as the temperature-sensitivity coefficient Q10; (3)The correlation of soil respiration rate and soil water content of 10 cm soil depth was low as a whole, but the influence was obvious. In addition to no precipitation showed significantly positive correlation, it almost off the mark between comparison and water content, and it negatively correlated between water addition and water content, especially the addition 130% was marked negative correlation; (4)In General, water addition 100% improved the soil respiration rate, expanded its excursion, water reduction reduced the soil respiration rate in the study region nature environment.

Abstract:Litter and soil hydrological properties of four types of Pinus koraiensis plantations in the South branch of the Songhua river-Ashi river’s Headstream were studied by using field investigation and experiment analysis method. It was shown that the litter total storage capacity in four types of plantations were in descending order of Pinus koreansis plantation (12.57 t/hm2), Fraxinus mandshurica-Pinus koreansis mixed plantation (9.96 t/hm2), Phellodendron amurense-Pinus koreansis mixed plantation (8.27 t/hm2) and Juglans mandshurica-Pinus koreansis mixed plantation (6.35 t/hm2). The maximum water-holding rate of litters ranged from 391.87% to 573.93%, the modified precipitation interception rate of litters ranged from 262.71% to 409.61%, both the ranking order as follow: Juglans mandshurica-Pinus koreansis mixed plantation, Phellodendron amurense-Pinus koreansis mixed plantation, Fraxinus mandshurica-Pinus koreansis mixed plantation and Pinus koreansis plantation. In four types of plantations, both water holding capacity and water holding rate had remarkable logarithmic correlation with soaking time, while the absorption rate and soaking time was a power function. In the soil layer of 0—30 cm, the average soil bulk density was the smallest in Juglans mandshurica-Pinus koreansis mixed plantation (0.99 g/cm3), while it was the largest in Pinus koreansis plantation (1.04 g/cm3). Juglans mandshurica-Pinus koreansis mixed plantation showed the maximum soil porosity (58.77%), whereas Pinus koreansis plantation demonstrated the minimum soil porosity (56.22%), and the non-capillary porosity ranged from 2.96% to 5.85%, being in descending order of Juglans mandshurica-Pinus koreansis mixed plantation, Fraxinus mandshurica-Pinus koreansis mixed plantation, Pinus koreansis plantation and Phellodendron amurense-Pinus koreansis mixed plantation. The maximum water-holding capacity and available water holding capacity per 10 cm soil depth were in Juglans mandshurica-Pinus koreansis mixed plantation, reached 587.67 t/hm2 and 58.47 t/hm2 respectively. The mean of its initial infiltration rate, stable infiltration rate, and infiltration coefficient were largest in Juglans mandshurica-Pinus koreansis mixed plantation too, reached 3.64 mm/min, 2.78 mm/min and 1.10 mm/min, respectively. Judging from the hydrologic properties of litter layer and soil layer, the water conservation and storage capacity was the strongest in Juglans mandshurica-Pinus koreansis mixed plantation, while it was the weakest in Pinus koreansis plantation. The research results could provide evidence for soil and water conservation.

Abstract:In order to investigate the beneficial regulations of soil and water conservation in different vegetation types of reclamation areas of open-cut coal mine dump, the research about the vegetation litter was carried out in the 5 typical vegetations of the reclaimed land, including Robinia pseudoacacia， Ulmus pumila， mixed forests (Robinia pseudoacacia and Ulmus pumila) , shrub and weeds, by means of cutting ring method. The results showed that the litter thickness and cumulated amount in 5 sample areas were in the order of forest>shrub>weeds land. The litter thickness was ranged from 0.8 cm to 1.64 cm, the cumulated litter amount was ranged from 0.72 t/hm2to 7.51 t/hm2; the maximum water holding capacity and water conservation ability of litter showed Robinia pseudoacacia maximum, the maximum water-holding rate of litter was 145.58%~206.58%, the maximum water-holding capacity was 13.11 t/hm2~123.98 t/hm2, the effective interception rate was 119.74%~166.05%, the effective interception was 10.09 t/hm2~98.76 t/hm2. The relationship of forest land between litter water-holding capacity and the immersion time was logarithmic function (Q=aln t+b). The litter water absorption rate reached the maximum value at first 0 h ~1 h, then the water absorption rate rapidly decreased in 1 h ~4 h, and finally decreased gradually. The relationship between litter absorption rate and immersion time was power function (V=atb). The study would provide reference for evaluating the water conservation efficiency of litter layer in different reclamation areas of open-cut coal mine dump, and provided scientific basis for the vegetation restoration and reconstruction of the dump.

Abstract:The analysis of temporal stability of soil moisture was a theoretical basis for obtaining accurate and reliable tempo-spatial distribution patterns of soil moisture and predicting the regional soil moisture. The volumetric soil moisture dynamics at different soil depth (0—20 cm, 0—40 cm, and 0—60 cm) on a Larix principis-rupprechtii plantation slope was measured by TRIME-PICO from May to November in 2015 in the small watershed of Xiangshuihe of Liupan Mountains. The temporal stability of soil moisture was analyzed by the cumulative probability functions, relative differences and Spearman rank correlation coefficients. The results showed that the soil moisture had a moderate variability both in time and space, and the degree of variation decreased gradually with increasing thickness of soil layers. The variability of cumulative probability for thicker soil layers (0—40 cm and 0—60 cm) was lower than that of the 0—20 cm soil layer under both dry and wet conditions. The mean relative differences of the soil moisture for the soil layers of 0—20 cm, 0—40 cm and 0—60 cm ranged from (－43.5%)~（47.9%）, (－42.9%)~（49.9%）and (－46.9%)~（40.0%）, respectively. The standard deviation of the mean relative differences (SDRD) decreased gradually with the increasing soil layer thickness. The SDRD of 0—20 cm, 0—40 cm and 0—60 cm soil layer were 11.1%, 8.3% and 7.8%, respectively. The soil moisture of all 3 soil thicknesses studied had a higher Spearman rank correlation coefficient (bigger than 0.7) and with a significant correlation, suggesting a higher temporal stability existed for the soil moisture of all the soil thickness studies. The representative points of the mean soil moisture of different soil layer thicknesses on the Larix principis-rupprechtii plantation slope were determined based on the temporal stability characteristic of soil moisture. With these representative points, the mean soil moisture of different soil layer thicknesses of the whole slope could be easily estimated.

Abstract:In order to effectively use and store rainfall in summer, and clear soil water dynamic change regularity with different planting system and soil tillage patterns in anniversary wheat field, it was implemented by using the method of field contrast in Linfen of Shanxi province, the effect of soil tillage patterns during the summer fallow period on soil water dynamics and water use efficiency of anniversary wheat field under multiple cropping millet in wheat stubble were studied. The results showed that, in little summer precipitation year, the soil water storage was minimum tillage>traditional tillage>no tillage in 0—200 cm soil layer at sowing period, and the soil water consumption was higher during whole millet growth period under multiple cropping millet in wheat stubble than that of the other three tillage patterns in summer fallow period. In great precipitation year, the soil water storage was millet stubble＜minimum tillage and traditional tillage in summer fallow period in 0—200 cm soil layer at green-turning and jointing stages, but it was opposite at filling and ripening stages. From sowing-returning green stages, the soil water consumption was lower in all soil layer under millet stubble than that of minimum tillage and traditional tillage in summer fallow period; and from returning green- jointing stages to filling and ripening stages, the soil water storage changed from accumulating to deficit in 0—200 cm soil layer; and from sowing-ripening stages, the soil water consumption was traditional tillage in summer fallow period>minimum tillage in summer fallow period>multiple cropping millet in wheat stubble in 0—200 cm soil layer. Throughout one year soil water accumulated at different degree under millet stubble, minimum tillage and traditional tillage in summer fallow period in 0-100 cm soil layer, and in 100—200 cm, 0—200 cm soil layer water saved under millet stubble, but minimum tillage and traditional tillage in summer fallow period were deficits. Water use efficiency was millet stubble>minimum tillage in summer fallow period>traditional tillage in summer fallow period. The study provided theoretical basis and technical support for correct planting of tillage system and soil tillage patterns in summer fallow period.

Abstract:In this paper, we evaluated the variations of soil water and explored the suitability of the soil water characteristic curve fitting model in interdune lowland at the southern edge of Gurbantunggut Desert. Using the pressure membrane apparatus, we measured the soil water characteristic curves at different soil depths (0—150 cm) in desert land. Combined with bulk density, grain size and saturated water content, the distributions of soil water characteristics and pore size in different soil layers were analyzed, and the applicability of Gardner model and van Genuchten model fitting was defined. Our data showed that the sandy soil release rate varied regularly with soil water suction rate in interdune lowland. Soil water characteristic curves in different soil layers showed a steep trend and strong water release in low suction range (0~100 kPa), while they presented a smooth and slow trend, with a high water holding ability in high suction range (100~1 500 kPa). The soil moisture characteristic curve was consistent with its physical properties. The distribution of soil pore size varied regularly, with increasing the proportion of large pores from the top to the bottom soil layer and the small pores held the biggest ratio in 20—40 cm soil layer, which was conducive to the rapid infiltration of the spring snow melt into the soil. In addition, our results found that both the two models fitted well with the measured data in this region. The VG model was better than G model in fitting the soil water characteristic curve in interdune lowland, but G model was simple in form, with few parameters and easy solving, which was much more convenient for practical application.

Abstract:Soil moisture and thermal condition were two key factors for crop production in Arid Region. The effects of different plastic film and tillage modes under mulched drip irrigation on the spatial variation of soil moisture and heat transfer were studied by the 2-year field experiment in Hetao Irrigation District. The experiment designed 4 treatments which included ridge tillage with full film mulching (LQ), ridge tillage with half film mulching (LB), flat tillage with full film mulching (PQ) and flat tillage with half film mulching (PB). Soil moisture in 0—120 cm profile was measured by drying method. Soil temperature was checked by ECH2O at the soil layer of 0—120 cm. The results showed that compared to LB, PQ and PB, LQ increased soil water contents by an average of 14.4%, 23.8% and 26.9% in 0—20 cm respectively at seedling stage. At jointing stage, LQ and PQ enhanced the same parameter by up to 32.6% and 5.8% than LB and PB in 0—40 cm respectively. The soil water content of ridge tillage in 0—60 cm was significantly higher than flat tillage during heading stage, however there was no significant different in 60—120 cm. Finally, LQ in 0—80 cm increased soil water content by 18.1%, 11.2% and 21.5% compared to LB, PQ and PB at maturing stage, respectively. Average soil temperature in 0—70 cm soil layers was significant higher in full film mulching than half film mulching. Compared to LB, PQ and PB, soil temperature of LQ increased 0.44 ℃ and 1.16 ℃, 0.93 ℃ and 0.22 ℃, 1.22 ℃ and 1.37 ℃ in 2014 and 2015 respectively. The changes of soil temperature were tented to be steady with increasing soil depth. Ridge tillage with full film mulching method could significantly increase soil temperature, enhance the soil water content and had obvious effects on restraining the loss of heat. It was clear that the optimal mulch and tillage strategies were beneficial to form better soil moisture and temperature environment and then increased crop yield.

Abstract:To ascertain the optimal urea-formaldehyde slow-release nitrogen (UFN) fertilization ratio, a wheat field experiment was conducted to study the effect of UFN on soil nutrients, grain production, nitrogen-use efficiency, and economic income in Huanghuaihai Plain. UFN treatments were set as five ratios with 30%, 40%, 50%, 60%, and 70% of total nitrogen fertilizer, abbreviated as UFN30, UFN40, UFN50, UFN60, and UFN70. The results were as follows, the trends for nitrogen release during the crop growth season showed as “raise-decline-raise-decline” under all UFN treatments. Relative to traditional urea fertilization treatment, both UFN40 and UFN50 treatments had the most favorable capacity that nitrogen was supplied to plants, which helped to maintain high nitrate, ammonium nitrogen, and alkaline nitrogen content in soils. This was beneficial to provide higher nitrogen nutrition for wheat growth. The grain yield in UFN40 and UFN50 was 11.36%~13.67% higher than that of conventional nitrogen fertilization treatment, respectively, while UFN30, UFN60, and UFN70 did not significantly change plant yield-related components. Nitrogen utilization efficiency increased by 13.65%~103.87% and-14.73%~75.47% with UFN application, as compared with urea basal fertilization and urea basal fertilization+ urea topdressing fertilization, respectively. UFN40 and UFN50 increased nitrogen-use efficiency and economic income by 31.83%~103.87% and 1 350 yuan~1 591 yuan per hectare, respectively. In a conclusion, urea-formaldehyde slow-release fertilizer taking as 40%~50% of total nitrogen should be recommended in wheat field.

Abstract:The effects of rice rotation in summer on the nitrification and ammonia volatilization of soil under greenhouse vegetable cultivation were studied based on the comparison of soil nitrification intensity, ammonia volatilization rate and the index about soil hydrothermal condition during greenhouse eggplant cultivation between two different crop rotation systems, greenhouse eggplant-rice rotation (GER) and greenhouse eggplant-summer fallow without plastic covering (GEF). The results showed as follows: (1)The soil nitrification intensity in GER was significantly higher than that in GEF during the different growth period of eggplant. The nitrification intensities of surface soil and rhizosphere soil on the seeding stage in GER were 56.6 mg/(kg·h) and 101.4 mg/(kg·h), with the increases of 34.8% and 42.4% compared with GER, respectively. (2)The soil ammonia volatilization rate and accumulative ammonia volatilization amount in GER were significantly lower than those in GEF. The gross ammonia volatilization amount of GER was 1.21 kg/hm2, with the decrease of 76.7% compared with GEF. (3)The NH4+-N amounts of surface soil and rhizosphere soil in GER were lower than those in GER during the different growth period of eggplant, whereas the NO3--N amounts in GER were higher than those in GEF. (4)The NH4+-N amounts of surface soil in GER and GEF after eggplant harvest were 30.4 mg/kg and 45.9 mg/kg, respectively, while the NO3--N amounts in GER and GEF were 265.4 mg/kg and 255.5 mg/kg, respectively, indicating the significant accumulation of nitrogen. The rice planting in summer alleviated the soil acidification and increased the pH, temperature and water content of soil during the greenhouse eggplant cultivation period. This also increased the nitrification intensity and decreased the loss of ammonia volatilization. However, the increase of nitrification intensity caused soil nitrate accumulation. This might lead to secondary salinization and nitrogen loss in soil. Therefore, the rational application of nitrogen fertilizer should be more concerned during the whole rotation period.

Abstract:Controlled-release urea (CRU) and urea (U) were used to investigate the effects of five proportions of controlled-release urea blended with urea (100% CRU, 25% U+75% CRU, 50% U+50% CRU, 75% U+25% CRU, 100% U) and two controls (no N fertilization , CK1), conventional fertilization (CK2, 60% U as basal and 40% U top-dressed ) on agronomic characters, dry matter accumulation and distribution, and yield in maize. Results were as follows: (1)Nitrogen supply could increase the plant height, ear height, and leaf area, compared to the CK2 treatment, the combination applications of controlled-release urea with urea could increase the plant height, ear height, stalk diameter, and leaf area, improvement effect of the mixing ratio of 75% treatments were the most strong among them. (2)Compared to the CK2 treatment, the combination applications of controlled-release urea with urea could meet demand of life on jointing stage, promote dry matter accumulation on silking stage, and dry matter quantity were improved finally, improvement effect of the mixing ratio of 50%-75% treatments were the most strong among them. (3)Compared to the CK2 treatment, the dry matter of the combination applications of controlled-release urea with urea were lower on distribution proportion of the stalk and leaf, however, the distribution proportion of grain increased, the most in the mixing ratio of 75% treatments. (4)With different ratio of controlled-release urea were always higher, the yield, 1 000-kernel weight, the grains per spike, ear length, and ear diameter increased firstly and then gradually decreased. The yield of the mixing ratio of 25%, 50%, 75%, and 100% increased by 3.70%, 8.83%, 11.23%, and 5.43% than the CK2. Therefore, applying controlled-release urea with a mixing ratio of 75% of basal dressing was most beneficial to meet the demand of life of maize, promote dry matter accumulation and distribution, and also could increase yield.

Abstract:From 2014 to 2015, set deep plowing with straw returning (DR) and rotary tillage with straw returning (RR), took rotary tillage without straw returning (CK) as the control, studied effect of current year and the following year with straw returning on soil available nutrients and microbial biomass under different tillage methods at Plain of Xi Liao River. The results showed that deep tillage with straw returning and rotary tillage with straw returning all could increase in various degrees of soil available nitrogen, potassium content and bacteria, fungi, actinomycetes number, straw returning with deep plowing had more obvious effect, the rotary tillage with straw returning had little effect on soil available phosphorus content. Straw returning the following year, according to average for 3 different soil layers at full ripe stage, compared with CK, the content of available nitrogen in DR and RR increased by 26.60% and 16.34% respectively, available phosphorus increased by 19.81% and 0.92%, available potassium increased by 23.95% and 12.53%, according to total of 3 different soil layers, the number of bacteria increased by 36.46% and 9.8%, the number of fungi increased by 22.10% and 21.90%, the number of actinomycetes increased by 23.55% and 17.38%. Compared with the current year and the following year, the growth rate of soil available nutrient was higher than that in the current year at jointing stage, and the growth rate of other periods was higher than that in the following year, the microbial biomass performance for the following year growth rate was higher than that in the current year. Compared with the control, the soil available nutrients and microbial biomass increased mainly in the 0—10 cm soil layer. Compared with the different growth stages, the soil available nutrients performance for full ripe stage was the biggest at the current year, and the following year at the jointing stage was the biggest.

Abstract:The spring wheat (Triticum aestivum longchun 27) selected as test material, a field experiment, which involved in three treatments were, 1)Whole field soil plastic mulching and irrigation (FMSI), 2)Whole field soil plastic mulching (FMS), and 3)Uncovered and bunch seeded (CK), had been conducted from 2012 to 2014 at Gansu Dingxi on northwest Loess Plateau (104°36′ E, 35°35′ N). The seasonal soil water content, biomass, yield and its components of spring wheat had been recorded, and the periodical water consumption, water consumption modulus coefficient, water consumption intensity, water use efficiency had been calculated, to reveal the water consumption characteristics of the whole field soil plastic mulching and bunch seeded spring wheat, and its effect on yield formation and water utilization. The average water consumption from sowing to jointing, jointing to heading, to Filling, and Filling to Maturity of FMSI in 2013 and 2014 were 159.5, 115.0 mm, 47.7 mm and 117.7 mm, the water consumption modulus coefficient were 39.7%，21.5%，13.8% and 25.0%, respectively, and there were no significant difference between 2013 and 2014. It’s indicated that the results could be served as the spring wheat water requirement pattern under whole field soil plastic mulching condition. The soil water storage in 0—300 cm soil profile of FMS was higher than CK in sowing, jointing and filling of spring wheat. From sowing to jointing, the water consumption intensity of FMS increased by 20.0%, 5.8%, but from filling to maturity, it decreased by 26.4%, 14.1% in 2013 and 2014 respectively, as compared with CK. The biomass of FMS was significantly higher than CK from 2012 to 2014. Especially, it increased by 95.7%, 42.8% and 108.7% than CK in maturity. The plant height, spike length, plant weight, spike weight, spike lets numbers, spike grain number, 1000-grain weight of FMS were significantly higher than CK, resulted in the increment of grain yield for 35.4%, 58.9 % and 61.9%, and increment of water use efficiency for 44.6%, 54.6% and 69.0% while without significantly increment of evapotranspiration from 2012 to 2014. Consequently, the FMS regulated the water consumption process in different precipitation year, improved the water consumption modulus coefficient and water consumption intensity in productive growth stage of spring wheat, this benefited to source development and resulted in increasing yield and WUE while decreasing evapotranspiration in filling .

Abstract:In southern Xinjiang oasis cotton fields, the river water was taken as control (CK), using salt water mixed with water, settings for 3 g/L and 5 g/L saline water, researched on the effect of saline water drip irrigation on water and salt transport features and cotton yield. The results showed that: Soil moisture content and soil salt content of 3 g/L and 5 g/L salinity in the whole growth period increased with the increase of salinity, before full-bloom stage (July 21) there was no significant difference of soil moisture content, but the highest soil salinity was CK, the soil salt content after full-bloom stage was 5 g/L>3 g/L>CK and its difference was significant (p<0.05). Vertical direction, soil moisture content increased with increasing soil depth, and with the increase of brackish water salinity, soil moisture content showed a trend of increase, which had a significant differences between treatment after full-bloom stage. With the increase of soil depth, the soil salt content showed the downtrend, the more times of drip irrigation, the more difference of different treatments, at full-boll stage (August 4) it reached significant level. Horizontal direction, the farther distance of water dropper head, the smaller soil moisture content, and the soil moisture content increased gradually with the increase of salinity. The soil salt content of 3 g/L and 5 g/L was lower than that of CK before full-bloom stage, after full-bloom stage the soil salt content declined along with the distance of water drops head, and was positive correlation with salinity. Lint yield of 3 g/L decreased by 2.1%, no obvious difference, but that of 5 g/L decreased by 9.6%, and there was significant difference. The main reason of declining lint yield was a significant reduction in the boll number per plant and single boll weight, but no significant effect on lint percentage. Therefore, before full-bloom stage cotton could use saline water for irrigation, and saline water salinity should not be more than 3 g/L.

Abstract:To study the effects of lower limit of saline water mulched drip irrigation on water salt transport and corn yield, a field experiment about mulched drip irrigation of corn with saline water was conducted in Changsheng experimental station. Tensiometer was used to guide irrigation, in each treatment the matric potential of soil 20?cm depth under the emitter was controlled higher than -10 kPa, -20 kPa, -30 kPa, -40?kPa, respectively. All treatments were repeated three times with the experimental plots following a complete randomized block design. Results showed that the shape of wetted body of mulched drip irrigation on sectional elevation of emitter which was perpendicular to the drip irrigation belt was approximated to semi-ellipsoidal. The water content of wetness soil layer would increase with increasing irrigation lower limit. The zone near maize root of all treatments appeared low salinity zone, surface layer out of the plastic film appeared high salinity area; -20?kPa and -30?kPa irrigation lower limit were moderate, they not only could leach surface soil salinity in the mulch more fully, but also did not lead to the salt in brackish water accumulation. All treatments 100?cm under the surface in and out of the mulch during growth of corn occurred salt?deposit. The depth of wetting layer of -10?kPa and -20?kPa irrigation limit were both about 60?cm. After maize harvest, all treatments occurred salt accumulation under the surface 100?cm, to ensure land salinity not accumulated year by year, massive irrigation to leaching large number of soil salinity in autumn or next spring was required. When irrigation frequency was too low, the maize yield decreased with decreasing irrigation frequency. Under the experimental conditions, the maize yield decreased with decreasing irrigation limits.

Abstract:To reveal the effects of artificial Mongolian pine forest on soil particle size parameters in southern Mu Us desert, soil samples (taken as two layers 0—20 cm and 20—40 cm) under different plant densities (925～2 700 plants/hm2) as well as the bare sand land (control check) were selected in Yulin rare desert plant protection base of Shaanxi Province. Soil particle size parameters such as average particle size, standard deviation, skewness, kurtosis and fractal dimension were identified and calculated by using laser diffraction technique. The results showed that in the study area, majority soil particle size was occupied by sand particles, followed by silt particles and then clay particles. Soil particle size parameters presented comparatively thick, poor sorting, positive skewness as well as middle or sharp kurtosis. Fractal dimension of soil was in range of 1.422～2.084. As affected by Mongolian pine plantation, the average particle size and fractal dimension values were continue to increase leading to constantly particle distribution optimization than that of bare sand land, especially in the top layer of soil profile, such effects were more obvious. Meanwhile, there were no obvious regularities in standard deviation and kurtosis along with the increase of stand density. And distribution of soil particles was not balance. The results indicated that stand density factor was not enough to cause the thickness distribution of soil particles toward the trend of balance.

Abstract:In order to investigate the effects of different maize planting densities and plastic film mulching on maize yield, soil water content and root growth in the rain-fed agriculture region of north-eastern China, the field experiment with different planting densities (67 500 plants/hm2, 82 500 plants/hm2，97 500 plants/hm2) and film mulching was conducted in the experimental field of Shenyang in 2014—2015. The results showed as follows：（1）In different growth stages of maize, mulching and planting densities had different effects on soil water content in different soil layers. In the upper soil layer of 0—20 cm, soil water content increased by 9.80%, 15.93% and 12.77% respectively for three stages (earlier stage, middle stage and later stage) with planning density of 6 7500 plants/hm2. In the soil layer of 20—40 cm, soil water content increased by 13.83% in the early growth stage of maize with planning density of 82 500 plants/hm2, and in the soil layer of 40-60 cm, soil water content (82 500 plants/hm2) increased by 15.47%, 4.11% and 8.96% respectively for three stages. (2)The effects of planning density on root length, root project area, root volume and root surface area were significant. This characteristic parameter showed a decreasing trend as the planting density increased. Root length, root project area, root volume and root surface area with the film mulching planting and planning density of 82 500 plants/hm2 increased by 44%，38%，38% and 33% respectively. (3)The grain yield decreased with the increase of planting density. When planting density was 67 500 plants/hm2, the 100-seed weight and grain yield were the highest. The highest 100-seed weight was 36.83 g, and the highest yield was 12 573.69 kg/hm2. These results showed that there was an optimal planning density of maize. Out of this density, the yield of maize decreased with the increase of the planning density. The research provided a theoretical basis for rational selection of optimal planting density and plastic film-mulching, which was also significant to improve rainwater use efficiency and maize yield in rainfed areas in Northeast China.

Abstract:Irrigation districted in low-lying areas of Ningxia, where drawing water from Yellow River, suffering from salinization and poor ecosystem problems. Aiming to construct vegetation rapidly in these areas, experiments of water and salt management that chose poplar (Populus) as target plant included five drip irrigation treatments, in which controlled soil matric potential (SMP) higher than -5 kPa, -10 kPa, -15 kPa, -20 kPa and -25 kPa respectively. Results showed low salinity zone, which enlarged as the irrigation water amount increased, appeared irregular oval. At the enhanced leaching stage that before the soil matric potential treatments was conducted, the salt leached rapidly with a decrease of 70.87% compared with the initial values and the water consumption per ECe unit (dS·m) decrease was 41.7 mm. As the soil matric potential (SMP) treatments conducted, the ECe and SAR from 0 to 40 cm depth soils had significant difference while significant difference was not showed in the whole depth soils. The ECe and SAR increased linearly as the soil matric potential controlled decreased. Principal component analysis of poplar’s growth factors，including height, crown width, stem diameter, diameter at breast height (DBH), and growth rate of treetop, showed the treatments of both -15 kPa and -5 kPa got scores higher than average value while others got lower scores than average value. Based on principle of efficient water use and the effect of salt leaching, the -15 kPa could be used as a controlled SMP value to instruct the poplar ecology forestry construction in this area.

Abstract:In situ simulation was performed on the corn stalks under the mode of planting and returning by nylon bag method. The experiment was conducted to compare the effects of different amounts of straw returning to field on soil total phosphorus, available phosphorus and different forms of organic phosphate. In the experiment, four levels of R0 (0%), R1 (0.44%), R2 (0.88%), R3 (1.32%) and three different returning depths of 0-15 cm, 15-30 cm and 30-45 cm were carried out. The results showed that the soil total phosphorus content did not change significantly with the increase of the amount of straw returning to field after 1 year. Compared with R0, the soil available phosphorus in R1, R2 and R3 increased by 27.0%, 49.3% and 64.1% respectively in 0-15 cm soil layer. The available phosphorus in 15-30 cm and 30-45 cm soil layers also showed a significant increase with increasing amount of straw returning to soil, and the increasing amount followed by the trend: 0-15 cm>15-30 cm>30-45 cm. Compared with R0, the contents of active organic phosphorus and high-stable organic phosphorus of R1, R2 and R3 in 0-15 cm soil layer showed no significant difference, and the middle active organic phosphorus decreased by 12.8%, 26.2% and 36.3% respectively, and the content of stable organic phosphorus increased by 25.1%, 53.5% and 61.6%. In 15-30 cm and 30-45 cm soil layers, soil moderate organic phosphorus increased respectively with the amount of straw returning and the content of moderate active organic phosphorus increased and the content of moderate stable organic phosphorus decreased, while there was no significant difference between active organic phosphorus and high stable organic phosphorus. The results showed that maize straw returning to field could increase the content of available phosphorus in soil by promoting the conversion of phosphorus from other forms of soil to available phosphorus. Maize straw returning could supply phosphorus source for direct use in the next season. Meanwhile, it could improve the moderate stability organic phosphorus content and reduce the moderate active organic phosphorus content in the soil.

Abstract:The effects of reclaimed land on soil aggregates under different land use patterns in the hilly-gully regions of Loess Plateau were studied to provide the scientific basis for improving soil stability and productive performance of reclaimed land. Five different land use types after reclamation of degraded cultivated land, included forestland (F treatment), rice (R treatment), maize (M treatment), vegetable (V treatment) and wasteland (CK treatment), were studied in the Nanniwan gully area of Yan'an, Shaanxi Province. The mean weight diameter (WMD), geometric mean diameter (GMD), aggregate processing damage rate (PAD) and fractal dimension (D) of >0.25 mm aggregates in wet sieve method and dry sieve of 0 ~ 40 cm soil layer soil were measured. The results showed that: (1)The number and size of soil aggregates in 0-40 cm soil layer were significantly better than those in CK treatment. The content of >0.25 mm aggregate (DR0.25) and (WR0.25) in 0-40 cm soil layer showed the opposite trend with the increase of soil depth. (2)The order of mean weight diameter (MWD) and geometric mean diameter (GMD) of soil treated by dry sieve method and wet sieve method was F treatment>R treatment>M treatment>V treatment>CK treatment, F treatment and R treatment on soil aggregates increased significantly than other treatments. (3)The results of wet sieve analysis showed that the PAD of soil aggregates in 0-40 cm soil layer showed similar Z-shaped trend, and the treatments were significantly lower than CK. (4)The fractal dimension (D) of each treatment was in the order of F treatment

Abstract:To understand variations in soil properties and the process of carbon uptake and store in arid areas under land reclamation interference, this paper was mainly through exploring the impact of reclamation age on physicochemical properties and soil inorganic carbon (SIC) in a depth of 0-200 cm soil profiles. Fubei farm of Sangong river catchment, a typical region with different reclamation history lands in Xinjiang province, was act as the study area. Soil profiles of lands in different reclamation years were used to analyze the variation of soil pH values, soil salt content and SIC. Our results showed that: (1)Soil pH enhanced with the increase of soil depth in farm lands. Besides, as the reclamation age extension, it was significantly decreased in 0-60 cm (P<0.05) but increased in 60-140 cm and 140-200 cm soil profiles. Soil salinity was accumulated in top soils that salt content distributed as a type of "S" in soil profiles. With the reclamation age extending, the accumulation layer of soil salt went down gradually and the average value of salt content in each section decreased. It indicated that the extension of cultivation history contributed to moving salt and alkali. (2)The values of SIC content and storage in 0-60 cm were significant less than those in 60-140 cm (P<0.05) and those in 140-200 cm soil profile (P<0.05). The percentage of SIC ascended in vertical direction. SIC content, SIC storage and the percentage of SIC in 0-60 cm increased after first decreased and then decreased again with the reclamation age extending. Comparing with that in original lands, SIC storage in 0-60 cm of fifty years reclamation age decreased by 55% and that in 0-200 cm increased by 11.74 kg/m2 and the percentage of SIC also decreased by 1.28%. (3)The significantly influence of reclamation age on soil pH, salt and SIC were in different soil depth, respectively, in 0-60 cm, 0-140 cm and 0-200 cm.

Abstract:Decomposition of agriculture waste materials in the soil needed a long time. In this paper, a five years pot experiment combined Bowman-Cole sequential extraction to determine organic phosphorous fractionation with application four kinds of agricultural waste materials to explore the long-term dynamic change law of the forms of organic phosphorus in black soil. The treatments included pig manure (PM), maize straw (MS), leaf manure (LM), mushroom dreg (MD) and chemical fertilizer only (NPK). The results showed that compared with applying chemical fertilizer only, concentration of organic P (L-OP) of PM treatment was significantly higher and continually reduced in 5 years, concentration of MS and LM treatments achieved the highest levels after 3 years, 2 years respectively. Application of pig manure, maize straw and mushroom dreg increased concentration of soil moderately labile organic P (ML-OP). The concentration of ML-OP continue decreased in 5 years after application of pig manure, while other treatments increased. The concentration of soil moderately resistant organic P (MR-OP) significantly increased but decreased year by year after applying agricultural waste materials, including straw treatment which was always higher than the rest. Soil highly resistant organic P (HR-OP) began to decrease from 2 years~3 years after application of agricultural waste materials. Applied pig manure significantly improved the active organic phosphorus forms for long time, ?leaves could decrease the content of HR-OP and fewer influence on the rest of the forms, maize straw and mushroom dreg had the similar trends, maize straw tended to increase the L-OP and MR-OP but mushroom dreg tended to increase the HR-OP content. Application agricultural waste materials could activate steady-state organic phosphorus in different extents. But apply chemical fertilizer only promoted MR-OP transform into HR-OP.

Abstract:In order to find out the adsorption characteristics of Mn (Ⅱ) and Ni (Ⅱ) in typical soil (browns soil and rice paddies sand ) in mining area of southern Shaanxi, and to provide certain theoretical basis for prevention and control pollution of manganese in the mining area, in this paper the adsorption behavior of Mn (Ⅱ) and Ni(Ⅱ) in typical soil was studied by using vibration batch equilibrium techniques, coupled with dynamics and thermodynamic absorption models and infrared spectroscopic (FTIR) analysis, it aimed to determine the mechanism and affecting factors of Mn (Ⅱ) and Ni (Ⅱ) absorption by the soil. The results showed that the absorptions of Mn (Ⅱ) and Ni (Ⅱ) by the two types soil achieved equilibrium within 120 min, the adsorption capacity of the metal on browns soil was much higher than the rice paddies sand, the maximum adsorption capacity of Mn (Ⅱ) and Ni (Ⅱ) on browns soil determined to be 2.12 mg/g and 1.19 mg/g，whereas on rice paddies sand reached 1.32 mg/g and 0.78 mg/g respectively. The adsorption kinetics process of Mn (Ⅱ) and Ni (Ⅱ) in the two kinds of soil could be well interpreted by three isotherm models (i.e., pseudo-first-order kinetic, bi-constant and intra-particle diffusion models), the alignment with the models for the browns soil of adsorption dynamics were higher than for the rice paddies sand. In two kinds of soil the adsorption isotherm of Mn (Ⅱ) and Ni (Ⅱ), Freundlich equation was superior to the Langmuir adsorption isotherm equation. Within the pH range in the study, pH value had little influence on the adsorption efficiency of Mn (Ⅱ) from aqueous solution, but had some influence on Ni (Ⅱ), whereas the desorption of the two kinds metal was affected by pH value, and metal could be desorbed from soil only when the pH value of solution was less than 3. The relation of basic physical and chemical properties of soil, adsorption parameters and FTIR analysis demonstrated that soil organic matter played an important role in adsorption of Mn (Ⅱ) and Ni (Ⅱ).

Abstract:Using the single variable laboratory experiment, the wetland sediment in tidal flats areas of Min river estuary were collected to research the effect of pH on the nitrification, denitrification and mineralization processes of the nitrogen (the pH conditions were setting at 2.5, 3.5, 4.5, 5.5, 6.5, respectively). The results suggested that: In the nitrification process, lower pH (the pH was 2.5) showed the obvious inhibition on the nitrification activity, however, at other pH conditions, the influence on the nitrification rate of the sediment varied little. Which indicated that the number and the activity of the nitrifying bacteria were typical limited under the strong acid surrounding. In the denitrification process, the denitrification rate of the sediment decreased with time but the denitrification activity increased. Besides, the strong acid condition (the pH was 2.5) in some degree had inhibitory effect on the denitrification activity. Results indicated that denitrifying bacteria in the sediment was not active or the acid resistance bacteria was rare under strong acid condition. Finally, mineralization of the nitrogen was researched and no universal?rule was found between the pH and the mineralization rate, which showed that the pH had no direct effect on the mineralization process of sediment in the wetland.

Abstract:Silicon (Si) was a basic element for many aquatic organisms and its biogeochemical cycle played an extremely important role in estuarine coastal ecosystems. Ecotone, as the across area of different typical vegetations, its ecological edge effect was obvious. However, little was known about the role of ecotone in these processes and most focus on typical vegetation, sediment and porewater. The Shanyutan wetland was the largest tidal wetland in the Min River estuary, southeast China. Yet the related researches had been only carried on about porewaters and sediments while little was known about Si distribution in typical vegetation communities and its ecotones. Two transects from land to sea were laid in July 2015 to analyze the spatial distribution of Si in plant-soil systems in typical vegetation communities and ecotones. Results showed that the biogenic silica content in vegetation of ecotones was higher than the vegetation of typical communities while the spatial distribution of different vegetations had significant differences (p>0.05), and the contents in Phragmites australis, Cyperus malaccensis, Spartina alterniflora and Cyperus compressus were 15.66 mg/g, 9.09 mg/g, 7.17 mg/g and 7.77 mg/g, respectively. The different vegetation tissues in high tide beach contained more biogenic silica than those in low tide beach. The aboveground parts of vegetation, such as litter, stem and leaf with the contents of 13.40 mg/g, 12.49 mg/g, 11.72 mg/g and 6.58 mg/g, respectively, had more biogenic silica contents than underground roots. Contrary to typical vegetations community, the allocation proportions of biogenic silica in underground tissues were higher than those in aboveground tissues in ecotones (P.australis and C.malaccensis) of the Min River estuary wetland. Biogenic silica contents in surface soil between two transects showed the same trend in low tide beach and the opposite trend in high tide beach. And the available silicon contents in surface soil between two transects showed a same trend from land to sea. This study found that the differences of ecological characteristics of different vegetations and its growth conditions, and discrepancies of topographic and hydrological conditions caused by tide might affect the accumulation, absorption and spatial distribution of silicon in wetland, this would be of great significance for studying the biogeochemistry of Si in estuarine tidal wetland.

Abstract:The purple soil was used as the test soil. An incubation experiment in the laboratory was conducted to explore the effects of sudden temperature change on soil organic carbon mineralization of the typical dry land soil (purple soil) sampled from the purple hilly region. Experiment consisted of three treatments, that was, treatment HW (constant temperature 20 ℃), treatment BW1 (a sudden cooling from 20 ℃ to 10 ℃) and treatment BW2 (a sudden warming from 20 ℃ to 30 ℃). In treatment BW1 and treatment BW2, the sudden temperature change both happened when soil organic carbon (SOC) mineralization rate was basically stable and maintained a relatively lower level at the temperature of 20 ℃(29th day). After the sudden temperature change, treatment BW1, treatment BW2 and treatment HW was cultivated for another 47d. The results showed that sudden temperature change had a notable effect on purple soil SOC mineralization (P <0.05). More specifically, treatment BW2 had significantly promoted soil SOC mineralization, however, treatment BW1 dramatically impaired that. Compared with the constant temperature (HW) treatment, the SOC mineralization rates of the two increased by 225.1% and decreased by 38.5%. There was a significant difference in the amount of SOC accumulated mineralization between each temperature treatment (P<0.05) within initial stage after sudden temperature change (30th ~44th d). And compared to accumulated soil SOC mineralization in treatment HW, that in treatment BW2 and treatment BW1 increased by 40.5% and decreased by 55.3% respectively. But with the extension of the culture time, the amount of SOC accumulation in each treatment did not find a significant difference. Indicated that the effect of sudden temperature change on purple soil SOC mineralization was time-bounded, which remained around two weeks. Combined with mineralization kinetic data, the results showed that sudden temperature change affected SOC mineralization by changing the labile SOC pool size.

Abstract:Effects of characteristics of soil particle composition, organic carbon content in different soil particles and the correlation between them were studied in Manasi county, Xinjiang province. Selected four years of reclamation of cultivated land as the research object, and soil samples collected from 0~300 cm soil layer, obtained the composition of soil particles by laser method, to investigate the long-term effects of tillage on soil particle composition and organic carbon content of different soil particles. Results showed that the research of regional soil particle composition in sand (about 21.0%~35.4%) and powder (about 46.0%~50.0%), lower significantly higher than the upper content, sand content and silt content was significantly lower than the upper and lower in the middle. With the increase of cultivated fixed number of year, the silty clay loam upper top layer (0~60 cm) was transformed into loam, the silt loam in 60~100 cm was transformed into loam, the soil texture in middle and lower (100~300 cm) had less change. The soil organic carbon content increased first and then decreased with the increasing of the year of cultivation, growth rate reached 71.8%, and the increasing of the length of the organic carbon increased the value of tillage. At the same time, the correlation between silt, sand and soil organic carbon content was not high, and the clay and organic carbon content showed significant positive correlation. The range of correlation coefficient (r) between soil clay and organic carbon content under unused (Y0), 20 years cultivation (Y20), 40 years cultivation (Y40) and 60 years cultivation (Y60) was (0.67*)~(0.75*), achieved significant difference (P<0.05). Human farming methods on the composition of soil particles and organic carbon content had an impact, so scientific and reasonable farming could increase soil carbon sequestration ability, had good protection effect on soil carbon cycle system.

Abstract:Slope cropland of purple soil was the main part of agricultural production in the hilly region of Sichuan basin, where there are large precipitation and concentration in summer and autumn. When the rainstorm occurred, the water and soil loses easily, which led to shallowing soil layer, decreasing the soil moisture and seasonal drought occurrence. Some researchers found that the straw, the biochar and the organic fertilizer were able to increase the soil porosity and enlarge the soil moisture, but there was rare in the slope cropland of purple soil. Thus, to investigate the effect of soil ameliorants on the composition and stability of soil aggregate and moisture storage capacity of slope cropland in purple hilly area, two-year filed experiment was conducted by employing five kinds of soil ameliorants including straw, organic fertilizer, biochar, carbonaceous ameliorant I and Ⅱ. The results showed that all these five carbonaceous ameliorants were also observed to have the ability on enhancing the sequestration and storage of soil for precipitation, which could further markedly increase the saturated soil moisture content and maximum effective water and flood detention storage and decrease the water content of wilting point. The effect of these five soil ameliorants on the maximum effective capacity followed the trend: Carbonaceous ameliorant Ⅱ>carbonaceous ameliorant I>biochar>manure>straw>CK. The soil bulk density and soil porosity also received valid improvement after applying these ameliorants (besides straw), which significantly decreased and increased, respectively. In addition, the mechanical stability and the water stable aggregate content of soil with particle size >0.25mm significantly increased after soil ameliorants applied, while the micro-aggregate (<0.25mm) content decreased, suggested that the soil ameliorant could promote the conversion of small aggregate to large aggregate with the best promotion observed for >5mm particle (increased 14.5 to 60.7% compared with the contrast). Employing these soil ameliorants had obvious effect (followed the trend: carbonaceous ameliorant I≈carbonaceous ameliorant Ⅱ>biochar>organic fertilizer>straw>control) on increasing the average weight diameter and stability index of aggregate. Correlative analysis showed that there was a positive correlation between total storage capacity, active storage capacity, flood detention storage capacity and total soil porosity, capillary porosity, content of large aggregate, and there was negative correlation with non-capillary porosity and content of small aggregate. Therefore, there was close relation between soil moisture preservation and soil porosity. Applying soil carbonaceous ameliorant was an important measure to improve the structure of purple soil and increase the ability of moisture holding and anti-erosion of purple sloping cropland by promoting the conversion of small aggregate to large one, decreasing the soil bulk density, increasing the soil porosity and enlarging the soil moisture holding and the soil effective water storage, which prevented sloping land from the damage of local seasonal drought. Moreover, the limiting factor of low soil moisture preservation in slope cropland of purple hilly area might be low organic matter content.

Abstract:Under low phosphorus stress, the benefits of Si application on improving Si accumulation, P accumulation and chlorophyll fluorescence parameters of maize during seedling stage were investigated using medium ZH2 and ZH115 by sand culture experiment. The treatments consisted of three P levels (0.01 mmol/L, 0.1 mmol/L and 1 mmol/L) and three Si (0 mmol/L, 0.75 mmol/L and 1.5 mmol/L). Maize seedlings were incubated for 28 days, then the items were measured, including chlorophyll fluorescence parameters of the first top fully expanded leaf, dry matter accumulation, Si content and accumulation, P content and accumulation. The main results were as follows: (1)The dry matter accumulation, Si and P accumulation amount of these two varieties (ZH2 and ZH115) reduced by 34.73% and 39.26%, 29.10% and 33.01%, 81.81% and 87.63% in average, meanwhile the open degree of PSⅡ reaction center, efficiency of lightcapture, efficiency of light energy transformation and electron transportation of the leaf all decreased significantly, and heat dissipation of the leaf also increased with P concentration from P3 to P2 and P1 in culture medium. (2)The dry matter accumulation, Si and P accumulation amount of these two varieties (ZH2 and ZH115) increased by 21.54% and 36.05%, 120.08% and 236.65%, 39.81% and 69.17% in average, meanwhile the open degree of PSⅡ reaction center, efficiency of lightcapture, efficiency of light energy transformation and electron transportation of leaf also increased significantly with Si concentration from Si1 to Si2 and Si3 in culture medium. (3)There were significantly positive correlation between P accumulation and Si accumulation in plant. Fv/Fm (XE), Fv′/Fm′ (XE′), Fq′/Fm′ (φPSⅡ), and ETR showed significantly positive correlation with P accumulation in plant, and the same with Si accumulation. When P concentration in culture medium was 1 mmol/L or 0.1 mmol/L, comparing to treatment of Si1, dry matter accumulation, Si accumulation, P accumulation, efficiency of light energy transformation and electron transportation of ZH2 and ZH115 all increased under the treatment of Si2 and Si3; but the treatment of Si2 and Si3 on improving above items was very weak when P concentration in culture medium was 0.01 mmol/L. In summary, the improvements in phosphorus deficiency tolerance of maize were resulted from increasing Si and P uptake and accumulation in plant, efficiency of light energy transformation and electron transportation of leaf, and decreasing in photo inhibition by Si application, even these benefit of it could be found more under normal P level.

Abstract:The nitrogen loss in farmland was one of the main reasons which led to agricultural non-point source pollution. The excessive nitrogen application rate and irrigation quota were two significant factors which led to the nitrogen loss in farmland. This research would be helpful to figure out the temporal-spatial distribution features of NO3--N in leaching water and the influence of two factors on NO3--N leaching loss with different water and nitrogen management patterns. Then made a safe and effective water-nitrogen management pattern. The experiment used a completely random split plot design method. The main plot was irrigation quota with three levels (W1: 525 m3/hm2, W2: 750 m3/hm2, W3: 975 m3/hm2). The split plot was nitrogen application with five levels (N0: 0 kg/hm2, N1: 80 kg/hm2, N2: 160 kg/hm2, N3: 240 kg/hm2, N4: 320 kg/hm2). Every irrigation quota had five treatments with different nitrogen application rate. There were fifteen treatments in total. The field experiment was carried out in 2014, 2015. Adopted the methods of porous PVC and soil auger to collect water and soil samples. Measured the concentration of NO3--N in leaching water and calculated the leaching loss of NO3--N. With the increase of nitrogen application, the two years’ average increase of NO3--N concentration by W1 was far below the two years’ average increase of NO3--N concentration by W2 and W3 within the soil depth of 0—40 cm. With the increase of irrigation quota, the average increase of NO3--N concentration by N1 and N2 were far below the average increase of NO3--N concentration by N3 and N4 within the soil depth of 0—40 cm. The largest average increase of NO3--N concentration was 52.5% which belonged to W3N3. The highest average concentration was 8.29 mg/L which belonged to W3N4. Compared with the treatments in 0—40 cm soil depth, the NO3--N concentration of treatments showed the overall declination within the soil depth of 40—80 cm. But the change trend of NO3--N concentration was consistent with the soil depth of 0—40 cm. Within the soil depth of 80—120 cm, the leaching loss of NO3--N was significantly influenced by the nitrogen application, irrigation quota, and the interaction of those two elements. When the irrigation quota was constant, the NO3--N leaching loss of 2014, 2015 would increase with the increase of nitrogen application. The NO3--N leaching rate of 2014, 2015 would decrease with the increase of nitrogen application. When the nitrogen application was constant, the NO3--N leaching loss and NO3--N leaching rate of 2014, 2015 would increase with the increase of irrigation quota. The crop needed sufficient NO3--N to absorb in root layer. The pollution of NO3--N leaching loss on the groundwater should be controlled in the safety range. Considering the two aspects above, this research recommended the W2N3 as the best water-nitrogen management pattern for experimental region.

Abstract:With climate change, meteorological drought threatens the development of agricultural economy.Using percentage of precipitation anomaly index to describe drought，with precipitation data from weather stations in 16 city in Shaanxi province，annual drought indices in the recent 50 years(from 1960 to 2012)were calculated. On this basis, analyzing the interannual variation of drought, the spatial distribution characteristics of drought intensity were analyzed by GIS10.1. Here we show that summer precipitation in Shaanxi province is more than that in winter. From northern part to southern part, the average annual precipitation increased. The number of drought event was 15, 17, 13, 16 of southern part, northern part, guanzhong area respectively during this 53 years. The average frequence of drought event was 28%. The average occurrence frequency of light, moderate, serious, extraordinary drought were 19%, 6%, 1%, 2%. Among them the occurrence frequency of drought in Suide city was the highest(39%).This research will provide a scientific basis for drought monitoring, evaluation, forecast and drought resistance strategy in Shaanxi Province.

Abstract:To explore the improvement effect of desertification soil by adding of dewatering sludge from sewage treatment plant as soil amendment and determine the appropriate adding amount of sludge, the soil structure, nutrition index, water retention character were tested under the dewatering sludge doping content of 5%,10%,15%, 10%,25%,30%,25%.Three kinds of soil which were suitable for farming were chose as control test sample. The results showed that density of soil particles and soil bulk density reduced（r=-0.99, r=-0.89），while soil porosity increased when the addition of sludge to the sandy soil (r=0.79). When the sludge adding amount was more than 10%, the improvement effects of soil bulk density and porosity reduced. However, organic matter content, moisture content and water-holding capacity appeared linear growth with mixing amount of sludge (r>0.99). The water retention ability of improved sandy soil was better than contrast soil. Amounts of nitrogen and phosphorus were significantly positive linear correlated with the adding amount of sludge.（r>0.95）. The content of total nitrogen and phosphorus of improved soil were closed to the comparative soil when the sludge amount was 15%~25%, while the content of total potassium was almost no changed. However, the effective potassium content of sludge effectively increased. The best blending amount was 10%~25% the physical and chemical properties of ameliorative desertification soil was closed to contrasted soil and suitable to vegetation growth.

Abstract:The double-ring infiltrometer was the most used and classic field method to measure soil water infiltration process and saturated hydraulic conductivity, and the sizes of inner and outer rings of the infiltrometer would affect the determination result. Seven groups of double-ring infiltrometers, with different inner and outer diameters, were laid out and conducted in the grassland flat field in the Heihe river upstream in Qilian mountains, to investigate effects of the size of the infiltrometers on the measurement of the infiltration process and saturated hydraulic conductivity. The results showed that if the inner diameters of double-ring infiltrometer were same, the larger the outer diameter, the smaller the stable infiltration rate and saturated hydraulic conductivity; and if the outer diameters were same, the smaller the inner diameter, the smaller the stable infiltration rate and saturated hydraulic conductivity. The stable infiltration rate and saturated hydraulic conductivity were significantly negative correlation with the buffer index of double-ring infiltrometers, but there was no clear correlation between the initial infiltration rate and the buffer index. Considering the simplicity of installation, water demand and apparatus accuracy, the double-ring infiltrometer with the diameters of 20 cm and 40 cm for the inner and outer rings was recommended to measure the soil water infiltration process and saturated hydraulic conductivity in the mountainous regions.

Abstract:In this study, we aimed to investigate the characteristic of seasonal snow at low hill area in Northeast. The time serials of snow parameters (snow depth, snow density and liquid water content) were discussed, based on the date collected by Snow Fork and ultrasonic snow deep sensor. The results showed that: The main period of snow cover was from November to February, and the correlative analysis showed that snow depth had a negative correlation with snow temperature and air temperature, while there was a positive correlation between it and snowfall. Most part of snow was melting at the period of 10:00 to 18:00. The snow depth had distinct positive relation to the snow temperature four hours ahead. At the beginning of snow covering (December 1st), the snow density of the bottom layer and the surface layer was 0.198 g/cm3 and 0.126 g/cm3 respectively. It decreased gradually from the bottom layer to the surface one, and the snow cover density of middle 5-10 cm layer was greater than the surface and bottom ones when the depth hoar was appeared within bottom snow layer. The average of snow liquid water content within 0-5 cm, 5-10 cm and 10-15 cm layer was 0.308%, 0.319% and 0.205% respectively. The liquid water content of snow cover, which showed a single-peak type with the variation of depth in each snow cover layer, within middle 5-10 cm layer was greater than that at the surface and bottom ones. There was a positive correlation between the liquid water content of snow cover and its density (r=0.866, p<0.05). This study could provide fundamental data for the?generation?of?snowmelt?runoff, snowmelt erosion prevention and the assessment?of ecosystem fuction in the area of seasonal snow cover.