Abstract:In order to research the impact of rainfall patterns on slope erosion in the rocky mountain area of North China,the loess cinnamon and the calcic cinnamon from this area were selected and indoor experiments were conducted. The experiment treatment included three patterns of simulated rainfalls with the same total rainfall and mean intensity,covering uniform type (60 mm/h),rising type (30~60~90 mm/h),and falling type (90~60~30 mm/h). The results indicated that: (1) The initial runoff generation time of different rainfall and patterns was negatively correlated with the rainfall intensity at the initial stage. The initial runoff generation time of the rising type slope was 1.98 and 4.15 times higher than that of the uniform and falling types,respectively. The order of total runoff and total erosion generated by different rainfall patterns was falling type > rising type > uniform type. The total runoff of the falling type was 1.05~1.12 times of other rainfall patterns,and the total erosion was 1.22 and 1.78 times of the rising and uniform types,respectively. (2) Under different rainfall patterns,the same rainfall intensity appeared in different rainfall stages,which made the processes of runoff and sediment production on the slope different. (3) The runoff and contribution rate of the same rainfall intensity at the initial stage of the rainfall pattern was smaller than that at the end stage. When the 30 mm/h rainfall intensity appeared at the beginning of the rainfall pattern,the erosion amount and contribution rate of the loess cinnamon was greater than that at the end stage,while the calcic cinnamon was the opposite.

Abstract:To clarify the influences of tillage and weeding and slope length on the losses of nitrogen (N) and phosphorous (P) under natural rainfall in purple soil area,9 plots combined with two land disturbances (tillage and weeding and natural restoration) and three slope lengths (20,40,and 60 m) were established to compare the runoff and sediment yield,and N and P losses. The results showed that slope length had no remarkable effect on the runoff and sediment yield under the same land condition (P>0.05),while tillage and weeding plots significantly differed the runoff and sediment yield from natural-restored plots under the same slope length (P<0.01). Natural-restored plots of 20,40,60 m respectively reduced runoff by 77.55%,62.62%,79.56%,and sediment yield by 85.21%,94.97%,96.25%,compared with the tillage and weeding plots. There were significant effects of land disturbance on runoff-related DN and DP losses under 20 and 60 m plots (P<0.05) and on sediment-related TN and TP losses across all plot lengths (P<0.01). Natural-restored plots could reduce the losses of DN and DP in runoff by 75.13% and 80.22%,and the losses of TN and TP in sediment by 96.07% and 96.38%,respectively. Rainfall intensity had significantly power relationship with runoff and sediment yield,and TN and TP losses with sediment-related under tillage and weeding plots,but there was no significant relationship under natural-restored plots. The results can provide theoretical reference for N and P losses and non-point source pollution control in the purple soil area.

Abstract:In order to study the erosion characteristics and hydraulic mechanism of cinnamon soil slope during long-term rainfall erosion,10 consecutive rainfall experiments were carried out under 60,90 mm/h rainfall intensity respectively by the mean of indoor simulated rainfall experiment. The characteristics of runoff and sediment discharge,hydraulic parameters change,and the relationship between runoff sediment concentration and hydraulic parameters were discussed. The results showed that: (1) Under the premise that the same rainfall intensity and rainfall event,the change of runoff was smaller with the increase of rainfall events number,but the sediment discharge of the sub-rainfall changed greatly. Under the rainfall intensity of 60,90 mm/h,the variation coefficient of sediment yield was 23.94% and 59.88%,and the sediment yield of the 10th rainfall was only 59.74% and 22.28% to the first rainfall. (2) The average sediment yield rate of each rainfall increased with the rainfall intensity,the runoff sediment concentration showed the decrease trend of power function with rainfall time. (3) Influenced by morphological changes of rills and soil coarsening on the slope of brown soil,the average flow velocity of 60,90 mm/h showed the descending trend of exponential function and power function in the process of erosion,respectively. Froude number showed the same trend with average flow velocity. The Darcy-weisbach resistance coefficient increased logarithmically in the process of erosion under 60,90 mm/h rainfall intensity. (4) The correlation relationship between runoff sediment concentration and average flow velocity,Froude number,Darcy-weisbach resistance coefficient and runoff power were extremely significant,respectively. The average flow velocity was the most closely related hydrodynamic parameter in the process of runoff sediment concentration change. The change of runoff sediment concentration is deeply affected by the dynamic process of average flow velocity of slope runoff.

Abstract:Soil erosion is a key process to alter landforms under modern geo-environmental conditions. It is also the main element to soil degradation,desertification and rocky desertification and is closely related to earth surface processes of soil,ecology and hydrology. The knowledge of climatology,geology,geomorphology,pedology,hydrology,and ecology are needed to analyze the dynamic mechanisms of soil erosion occurring and development. However,the boundaries of temporal and spatial scales need to be identified clearly. Soil erosion is closely related to soil and water conservation and they are stimulated to each other. The temporal scale of soil erosion research focuses on rainfall event,month,and year. The main topics are erosion processes of rainfall event,seasonal and inter-annual variations in soil erosion. The time scale should be less than 100 years. The spatial scale of soil erosion research should be focus on small watershed. Based on the vertical distribution of soil erosion in small watershed,site,hillslope,gully and small watershed are commonly selected to study soil erosion. Nevertheless,the contents and methods are quite different from different scales. Soil erosion includes three sub-processes of soil detachment,sediment transport and sediment deposition. The key influencing factors and the research accumulations of these sub-processes are significantly different. The studying topics change with the temporal and spatial scales. The detach-limited and transport-limited as well as their altering threshold conditions should be always remind in mind to understand your experimental results. The future studies should be enhanced on rill network and its temporal-spatial variations,sediment deposition,dynamic mechanism of gully formation and evolution,mechanism of gravity erosion development,process-based soil erosion model for small watershed.

Abstract:The hydraulic characteristics of rill erosion were studied by using runoff scouring experiment under the different steep Loess slope gradients(25°,30°,35°,40°,45°,50°) and the different flow discharges(0.6,1.0,1.5,2.0,2.5 L/min). The results showed that velocity decreased first,then kept smooth and steady as the scouring time. The Reynolds number of the flow varied between 199.996 and 873.482 in the erosion process. It was affected mainly by the flow discharge which was in a linear relationship with flow discharge. The Froude number of flow was larger than 1 in the whole experiments,which indicated that the rill flow belonged to the supercritical flow condition. Meanwhile,the Froude number of rill flow was in a reciprocal decreased relationship with flow. Darcy-weisbach resistance coefficient (f) was positively related to flow and was in a power function relationship with the Reynolds number.

Abstract:Field experiment was conducted in black soil region of Northeast China to reveal the effects of straw mulching on runoff,sediment and nitrogen and phosphorus loss in different slope experimental plots at different growth periods of corn. The results showed that,surface runoff,soil,nitrogen and phosphorus losses were increased with the increased slope. Under the condition of corn planting,rainfall was positively correlated with surface runoff,but not for soil loss. The reduction rate of straw mulching on soil loss increased with the decreasing slopes. The resistance control rate of straw mulching on surface runoff and soil loss both exceed 90%. Dissolved nitrogen was the main contributor in nitrogen loss in soil,which accounted for more than 60% of total nitrogen. The loss of phosphorus was mainly granular phosphorus is the dominant phosphorus form,which accounted for more than 80% of the total phosphorus. Straw mulching had a resistance control rate of more than 85% for total nitrogen and total phosphorus in soil,which was of positive significance for controlling soil erosion and reducing the risk of non-point source pollution.

Abstract:In order to increase crop yield,farmers usually improved soil texture by mixing soil with sand in the Chinese mollisol region. This study was conducted to analyze impacts of different proportions of soil mixed with sand (0,10%,20% and 30%) on slope erosion under three slope gradients (3°,5ånd 7°) based on simulated rainfall experiments. The results would provide scientific foundation for agricultural production and soil erosion control in this region. The results showed that the impacts of different proportions of soil and sand mixture on runoff were greater than those of slope gradients,which increased with the increase in slope gradient. As the proportion of sand mixed in the soil increased,the mean runoff velocities varied from 5.2~5.3 cm/s to 2.7~3.4 cm/s and runoff rates and total runoff also decreased with the minimum values occurred in the 30% treatments. Sediment rates first increased and then decreased with the increasing proportion of sand mixed in the soil and slope gradient. Similar trend was found in sediment yields and the 10% and 20% treatments had the greater values than others. It could be include that soil mixed with sand less than 20% could decrease the runoff but increase soil erosion. Therefore,the effects of soil mixed with sand cannot provide a comprise solution for preventing soil loss in Chinese mollisol region. However,a moderate proportion of sand mixed in the soil can be used as an altenative agriculture technical measure by considering its ecological and economic benefits.

Abstract:Taking the typical lime soil grasslands,returning farmland to grass,forest and grass intercropping in karst plateau canyon areas as research objects,hierarchical collection of the entire profile soil and the improved BCR extraction method through redundant analysis (RDA) were used to analyze the morphological characteristics of soil calcium and its influencing factors under different ecological restoration models. Studies showed that under different ecological restoration states,the soil calcium,water-soluble calcium,and acid-soluble calcium had the highest mass fractions in the intercropping forest and grass,and grassland soil had the highest exchangeable calcium mass fraction. The organic calcium content was not significantly different in soils under different ecological restoration models. The calcium form to total calcium exists in the order of exchange state > acid soluble state > organic state > water soluble state. In the vertical direction,the contents of total calcium,available calcium,and acid-soluble calcium in the cultivated land and returning cultivated land in surface layer were smaller than those in the bottom layer,but surface layer>bottom layer for the forest and grass intercropping land and grassland. The organic calcium content did not change much on the profile,and the average value was about 0.33 g/kg. Available calcium and acid-soluble calcium had spatial differences and surface aggregation under different ecological restorations. There were very significant positive correlations among the basic physical and chemical properties of the soil such as pH,organic matter,CEC,total nitrogen,and available nitrogen. Through redundant analysis,it could be concluded that soil CEC,nitrogen,and pH were the main factors affecting the distribution of calcium forms. These research results are helpful for understanding the rules of soil calcium migration and transformation in karst mountainous areas. It could provide scientific basis and theoretical guidance for the restoration and reconstruction of ecological environment and soil and water conservation in karst ecologically fragile areas.

Abstract:In order to deeply understand the soil erosion mechanism of ridged farmland on brown soil,this paper used a 1.60 m×0.53 m test soil trough and designed two rainfall types,namely,intensive-type (70~70~100~100 mm/h) and reduced-type (100~100~70~70 mm/h),and artificial simulated rainfall tests on 2 slopes (9° and 18°). Each rainfall type is divided into two phases (phase I,phase Ⅱ),and two sessions of rainfall of the same raininess at each stage,and each session of rainfall lasts 20 minutes. The results show: (1) Raininess has a significant effect on runoff (P <0.05). Runoff at 100 mm/h rain intensity is greater than 70 mm/h. Under the reduced rainfall type,the slope has a significant effect on runoff (P<0.05),while under the intensive rainfall type,the slope at different stages has different effects on runoff. (2) Raininess has a significant effect on sediment yield (P<0.05). During the rainfall of Phase I,the average sediment yield per minute at 9° and 18° slopes at 100 mm/h raininess was 23.98 times and 9.07 times of 70 mm/h raininess. Under 70 mm/h raininess,the slope has a significant effect on sediment yield (P<0.05),while under 100 mm/h raininess,the slope at different stages has different effects on runoff. (3) The time sequences of 100 mm/h raininess in different rainfall types has no significant effect on sediment yield (P>0.05); under 70 mm/h raininess,the overall sediment yield is smaller,basically below 15 g/min.The time sequences of the same raininess in different rainfall types had significant effects on runoff (P<0.05). (4) The total runoff is as follows: 9° reduced-type > 18° reduced-type > 9° intensive-type > 18° intensive-type; the total sediment production is in descending order: 18° intensive-type > 18° reduced-type > 9° reduced-type > 9° intensive-type. Under different rainfall type,after the change of rain intensity,the cumulative runoff and cumulative sediment yield increase rate and the change of rain intensity are consistent.

Abstract:In order to study the effect of different fertilizer concentration (Urea) on soil hydraulic parameters,the sandy loam of three-stage terrace and clay loam of the first terrace in Yangling District of Shaanxi Province are used as the test soil,the parameters of soil hydraulic under different fertilizer concentration were estimated by numerical inversion method,and analyzes the influence of the change of soil hydraulic parameters on the cumulative infiltration quantitatively,Finally,the estimation formula of soil hydraulic parameters considering the change of fertilizer concentration was established. The results showed that with the increasing of fertilizer concentration,the saturated water content (θ_s),shape coefficient (n) and saturated hydraulic conductivity (K_s) of soil is increasing,but the suction of intake reciprocal value (α) decreased with the increasing of fertilizer concentration. The sensitivity of soil hydraulic parameters to cumulative infiltration is n > θ_s > K_s > α,and the influence of α on cumulative infiltration is less than 10%. In this paper,the relationship between θ_s and K_s and the concentration of fertilizer solution is exponential function. Utilizing estimation result simulated the cumulative infiltration amount and water content of soil profile in the process of one-dimensional vertical infiltration,and compared with the measured value,the two are showing no difference,It shows that the formula of soil hydraulic characteristic parameters considering the change of fertilizer concentration is reliable,this study can provide theoretical basis for water and fertilizer management of farmland.

Abstract:To better explore the characteristics of nitrogen transportation in a small typical agricultural catchment,the water nitrogen form,concentration and loss fluxes were continuously monitored for one year. The results showed that: (1) During the observation period,the significant seasonal variations in water nitrogen concentrations were observed and the year-round average concentration of total nitrogen (TN),nitrate nitrogen (NO₃^-—N),ammonium nitrogen (NH₄⁺—N),and dissolved organic nitrogen (DON) are 2.14 mg/L,0.77 mg/L,0.25 mg/L,and 0.51 mg/L,respectively; the NO₃^-—N is the main form of transported N in the small catchment. (2) In the spring (March to May),the N transport fluxes contributed for 43.56% of the annual total nitrogen fluxes,while in autumn (September to November),the N transportation fluxes only accounted for 3.70% of annual total N transportation fluxes. (3) The run-off and human activity are the major drivers of the nitrogen transportation in the small agricultural watershed of hilly landscape.

Abstract:A one-year continuous field monitoring study at fixed observation positions was conducted on a sand belt site in the southeast edge of Mu Us desert land,with continuous monitoring of soil water potential and temperature. With the sand surface first reshaped into furrow-and-ridge form,the in-situ field test had 3 treatments,i.e.,the ridge section one was covered with plastic membrane plus weed-blocking geotextile (MB); section two covered with weed-blocking geotextile only (DB); and section three exposed or uncovered to serve as the blank contrast (CK). Soil water potential and temperature were monitored using MPS-6 probes at 5,15,30 cm below the furrow surface,at 30 minute intervals,along with meteorological data above the soil surface. Results showed that: (1) The daily variations of soil water potential under the 3 treatments all showed characteristics of a Cosmic function,the daily soil water potential at the 5 cm depth was the most varied in the three groups,varying between -600 and -120 kPa,and showing MB > CK > DB. At the 15 cm depth,the value was higher with smaller variation between -180 and -90 kPa,showing DB > CK > MB. At the 30 cm depth,the soil water potential is virtually stable,with high water potentials for MB and DB stabilized at about -100 kPa,and much lower stable potentials for CK at about -285 kPa; (2) The annual variation of soil water potential showed two valleys,including the freezing-thawing period in the winter and the strong evaporation period in the summer. The annual averages among the 3 groups show that: at 5 cm MB > CK > DB,at 15 cm DB > CK > MB,and at 30 cm MB=DB>CK. The main reasons are that under the condition of MB and DB,the accumulated heat in the soil during the day time is higher,and the upward temperature gradient at night is higher,then the soil water at 15 cm depth moves up and accumulates under the surface membrane and it would be evaporated without the membrane. Therefore,the water potential at 5 cm below the surface is larger,while the water potential at 15cm is smaller. At the same time,under the condition of MB,the rainfall infiltration depth is the largest,so is the surface water content; Under MB and DB conditions at 30 cm,the water potential is approximately the same,but both are larger than that under CK. The predominant reason is that the rainfall in this area is small,and most rainfall cannot infiltrate to 30 cm depth without mulching; (3) When the 3 groups were analyzed for the total 0-30 cm soil layer,the soil water potential was greatly affected by relative humidity and wind speed of the atmosphere during freezing-thawing period. In the non-freezing-thawing period,soil water potential was most influenced by wind speed,followed by atmospheric temperature and relative humidity. It can be concluded that the moisture retention effects at 5 cm soil depths was better with MB treatment,while DB was better for 15 cm soil depth,and both MB and DB were better for 30 cm soil depth. These results could be used as a reference for sand fixation and revegetation in the desert area.

Abstract:Using laboratory artificial simulation rainfall experiment,the runoff process was observed on the scale of runoff plot,and the change process of soil volume moisture content was observed with Watchdog 1400 soil moisture automatic monitoring station to study the water infiltration characteristics of the slope under litter cover. The results were as follows:(1) The lag time of soil infiltration increases with the increase of litter coverage,and the slope was 10°>5°; (2) The infiltration rate of soil increases with the increase of rainfall intensity and litter coverage,and decreases with the increase of slope; the soil water storage first increases and then decreases with the increase of coverage,and the rainfall intensity is 120 mm/h>60 mm/h; (3) Stepwise regression shows that the soil infiltration lag time,infiltration rate and water storage capacity are linearly related to the amount of litter coverage,the lag time,infiltration rate and litter coverage are positively correlated with each other,the water storage and coverage has a quadratic function. The results can provide a basis for the research on the water source conservation function of the low-efficiency forest litter of Pinus massoniana.

Abstract:In recent years,sediment load in many rivers around the world has undergone significant changes,which may greatly affect ecological environment and economic development of the basin. Exploring the evolution of sediment load in the Weihe River will provide a theoretical basis for the comprehensive management of the Weihe River Basin and the regulation of water and sediment relations. This study attempted to investigate the spatial and temporal variation of sediment load in 15 hydrological stations in the Weihe River basin during the period of 1961-2015. The results showed that the average sediment load in the Weihe River Basin from 1961 to 2015 showed a significantly decreasingtrend. The annual sediment load atXianyang,Zhuangtou and Zhangjiashan stations decreased at a rate of 0.039 0 billion t/a,0.017 4 billion t/a,and 0.041 4 billion t/a,respectively. Among the 15 hydrological stations,the annual sediment load atZhangcunyistation showed a significant increasing trend,while Hongde,Yuluoping and Qingyang stations showed no significant decreasing trend,and the remaining stations showed significant decreasing trends (P<0.05). Both correlation analysis and partial least squares regression were applied to quantify the relationship between sediment load and potential driving factors. The sediment loadhad good correlations with the Precipitation Concentration Index,Vegetation Coverage Index,Grassland Area Ratio,Minimum Elevation,and Average Slope.

Abstract:An artificial rainfall simulation experiment was conducted at the intensity of 90 mm/h,under different straw lengths and different straw coverage to study the characteristics of runoff and sediment production on the slope and the regularity of runoff and sediment production process. In order to quantify the effects of different wheat straw lengths and mulches on the characteristics and process mechanisms of slope runoff and sediment yield,as well as the benefits of water and sediment reduction efficiency under different straw conditions. Results showed that: (1) Under the same straw length,with the increase of straw coverage,the yield and sediment yield decreased significantly (p<0.01). At the same coverage level,with the increase of straw length,the yield increased significantly (p<0.05),and the yield of sand increased significantly under the coverage of 4.5 t / hm² (p<0.01). (2) The initial runoff time of the straw-covered slope surface was 6.23 times longer than that of the bare slope surface,and the average production flow rate decreased by 19.5%,the sediment yield decreased by 31.6%. Covering measures effectively inhibited the trend of trench erosion to cut trench erosion by protecting the structure of the soil. The process of runoff and sediment production is affected by the interaction of straw length and mulch. The effect is more prominent on the process of runoff. (3) With the increase of coverage,the benefits of water and sediment reduction increased significantly (p<0.01); with the increase of length,the benefits of water and sediment reduction decreased to 17.26% and 27.97% respectively. The slope runoff yield,sediment yield,water reduction,and sand reduction benefits under the different covering conditions have a binary linear relationship with straw length and straw coverage. (4) Under the experimental conditions,when the straw length is 3 ~ 5 cm,with the amount of 4.5 t/hm²,the optimal water and sediment reduction benefits are achieved.

Abstract:The simulated rainfall experiments were conducted to explore the loss rules of runoff,sediment,and nutrient on the loess vegetated sloping land under the coupling effects of different rainfall intensity (60 mm/h,90 mm/h,120 mm/h),slope (10°,15°,20°),and biochar content (0,3%,6%).The results showed that: (1) The loss of runoff,sediment,and PO₄^3-—P increases with the increase of rainfall intensity,and NO₃^-—N increases firstly and then decreases with the increase of rainfall intensity. The rules of runoff,nitrogen,and phosphorus with slope were not obvious. The influence of rainfall intensity was greater in the linear relationship between the rainfall intensity,slope,and the changing rate of k value (sediment yield rate coefficient). (2) The processes of runoff and sediment yield were similar,they both first rose and then stabilized with the progress of rainfall. The NO₃^-—N had a power function relationship with the rainfall duration. The ratio of the maximum concentration to the minimum concentration of PO₄^3-—P during loss was between 1 and 2. In the process of sediment yield and NO₃^-—N loss,the correlation between rainfall intensity and biochar was extremely significant. (3) The increase of biochar content (≥3%) could increase the sediment yield and loss of PO₄^3-—P. When the rainfall intensity was 60 mm/h and 90 mm/h,the amount of NO₃^-—N loss decreased firstly and then increased with the increase of biochar content. When the rainfall intensity was 120 mm/h,the amount of NO₃^-—N loss depended on the amount of added biochar. The results can provide scientific guidance for the management of soil and water resources in the loess hilly and gully region.

Abstract:Loess cave is closely related to other erosion processes,such as landslide and gully erosion,and aggravates the degree of soil and water loss in the loess plateau. However,the distribution characteristics and the erosion threshold of loess cave are not clear yet. This study uses unmanned aerial vehicle (UAV) to acquire the high resolution image and digital surface model (DSM) of the study area. Identifying the loess cave,collecting its land use type and measuring its average length based on image as well as extracting its terrain data such as slope,aspect,curvature and drainage area,we analyze the distribution characteristics of the loess cave. The results show that the average length of loess cave is mostly shorter than 4 m. The loess cave tends to develop in pasture area rather than in arable land and requires certain terrain,mostly develops in the concave slope with water converges. The number of loess caves that develop on shade slope is more than that on sunny slope. Also,the area exits loess cave is usually with the tangent value of slope between 0.4 to 1.0 and the drainage area less than 3 000 m². Drawing the erosion threshold of loess cave rely on the statistics data of the tangent value of slope and drainage area and comparing the erosion threshold of loess cave with that of shallow ephemeral gully and gully,the erosion threshold of loess cave can be applied as formulas SA^0.150=0.368 and SA^0.135=7.580,which is widely enough to cover the erosion threshold of shallow ephemeral gully and gully. The evolution of shallow ephemeral gully and gully is related to that of loess cave. The development and transformation of the shallow ephemeral gully and gully are promoted by the collapse and connection of the loess cave,thus aggravates the degree of soil and water loss in the loess plateau. This study quantifies the distribution characteristics of the loess cave and establishes the contact among loess cave,shallow ephemeral gully and gully. It deepens the understanding of the process of the loess cave.

Abstract:In order to investigate the response characteristics of soil infiltration on different boulder outcropping slopes to rainfall in karst area,the influence of four boulder outcropping conditions and five rain intensities on infiltration was studied. Field artificial rainfall simulation method was adopted. The results showed that: (1) When the rainfall intensity was 30 mm/h,the size of the boulder outcropping rate had no significant effect on infiltration. However,in the other rainfall intensities,the rate of boulder outcropping was 5.4%,which had little effect on infiltration; while the rate of boulder outcropping was 13.1%,which inhibited infiltration,and the rate of boulder outcropping was 42.9%,which promoted infiltration. In the early period of rainfall,the existence of boulder could promote the infiltration. (2) When the boulder outcropping rate and rainfall remained unchanged,the stronger the rain,the less the infiltration. While the average infiltration rate increased first,then decreased and then increased again. In the early period of rainfall,with the increases of rainfall intensities,the infiltration volume decreased first and then increased. And the early infiltration rate increased with the increases of rain intensities. In both cases,the inflection point occurred when the rain intensity was 90 mm/h. (3) After simulating the infiltration process,it was found that universal empirical model showed better fitting effect than Kostiakov model on the boulder outcropping slope.

Abstract:Amounts of anthropogenic intrusions are mixed into the urban green land soil with rapid urbanization,which lead to the alteration of solid-liquid-gas composition and porosity characteristics in soil system,but its effect on the infiltration process of soil is still unclear. The influence of typical anthropogenic intrusions (brick and concrete fragments) on soil infiltration characteristics in urban green land was studied according to the simulation experiments by one-dimensional vertical ponding infiltration in soil column. The results showed that: (1) Anthropogenic intrusions decreased the infiltration rate,cumulative infiltration amount,wetting front depth,and soil volumetric water content in urban green land,and more obvious inhibition on infiltration in green land soil was observed in concrete group than bricks group with the equal anthropogenic intrusions ratio (P<0.1). (2) With the anthropogenic intrusions ratios increasing from 10% to 20% in urban green land,the soil infiltration rate,cumulative infiltration amount,wetting front depth,and soil volumetric water content showed a continuous decreasing or slightly increasing trend,but all were not significant (P>0.1),which indicated that the inhibiting effect of anthropogenic intrusions on the soil infiltration was gradually weakened. (3) With different types and ratios of anthropogenic intrusions,Kostiakov model was mostly fitted to the relationship between cumulative infiltration amount and time. This research will provide scientific basis on the constructive establishment of sponge city in the future.

Abstract:To study the influence of protective farming methods on wind erosion in farmland and particulate emission in the surrounding areas of Beijing city,the wind erosion rates of farmland and the emission situations of TSP,PM₁₀,PM_2.5,and PM₁ under different wind speeds and different degrees of coverage were compared by wind tunnel experiments,and the proportions of these 4 kinds of particulates in Aeolian deposits were analyzed. The results showed that: (1) When the wind speed is less than 12 m/s,a mere 20% of straw coverage would significantly lower the wind erosion rate,and when the wind speed is greater than 16 m/s,a coverage rate of at least 40% could resist wind erosion effectively. (2) The relationship between the emissions of TSP,PM₁₀,PM_2.5,PM₁,and wind speed was a positive exponential function,and that with the coverage was a negative exponential function. As wind speed increases,the releasing abilities of 4 fine particulate matters could be represented like this: A > B1 > B2 > B3 > B4 > B5. When the coverage rate was less than 10% or greater than 60%,the differences of bust sizes of fine particulates decreased as wind speed rose,and when the rate upped to more than 60%,the bust size tended to be stable. (3) The proportions of 4 fine particulates in Aeolian deposits decreased as the wind speeds increased,and the numbers became stable when the coverage rate was greater than 60%.

Abstract:In order to reveal the relationship between the litter water-holding capacity of the main afforestation species and the soil physical properties under the forest in sandstone area,the water holding capacity of the litter layer under 6 forest types and the physical properties of the soil layer and the water holding capacity of the 0—50 cm soil layer in Jungar Banner sandstone area were investigated. The results showed: (1) The thickness of litter layer under 6 forest types in the sandstone area varied from 0.73 to 2.77 cm and the total volume varied from 1.47 to 7.93 t/hm². The total litter volume of different tree species was consistent with thickness in the order of Pinus tabulaeformis > Platycladus orientalis > Hippophae rhamnoides > Caragana korshinskii > Prunus sibirica > Abandoned land. It was found that the thickness of semi-decomposed layer of litter and its accumulation were significantly less than those of undecomposed layers by comparing the two layers of 6 types of forest stand litter. (2) The order of the maximum water holding ratio was Abandoned land < C. korshinskii < H. rhamnoides < P. sibirica < P. orientalis < P. tabulaeformis,among which the maximum water holding capacity of litter under P. tabulaeformis reached 267.32%,and the maximum water holding capacity in abandoned land was the smallest,and the minimum was about 149.48%. The maximum water holding capacity of the 6 forest stands was in the same order as the effective litter storage quantity,which was P. tabulaeformis > P. orientalis > P. sibirica > H. rhamnoides > C. korshinskii > Abandoned land. The effective interception volume of the undecomposed litter was greater than the semi-decomposition layer. (3) It was found that the water holding capacity,water absorption rate,and soaking time of the undecomposed layer and semi-decomposition layer displayed the logarithmic relationship of Q=kln t+b and the V=ktⁿ. (4) The soil bulk density of the 6 forest types showed little change. The total porosity changed in the order of P. tabulaeformis forest > H. rhamnoides forest > P. orientalis > C. korshinskii > Abandoned land > P. sibirica. The non-mathematical porosity was in the order of H. rhamnoides > P. orientalis > P. tabulaeformis > P. sibirica > abandoned land > C. korshinskii. The maximum water holding capacity was 17.43 mm in P. tabulaeformis forest. The minimum water holding capacity was 8.89 mm in P. sibirica forest. The order of the water holding capacity of the non-capillary followed the order of non-mathematical porosity of 6 forest stands.

Abstract:Aiming at the serious problem of soil erosion on the Loess Plateau,combined with the current situation of water shortage in the region,under the condition of limited vegetation measures,the convex slope was taken as the research object,and the grass belt was laid on 5 different positions on the upslope,and the indoor water discharge was used. The experiment studied the slope erosion process and sediment particle size fractionation characteristics under different vegetation spatial positions,and clarified that the vegetation can effectively exert the soil and water conservation effect,and primitively proposed the optimal position of soil and water conservation effects under low vegetation coverage. The results showed that: (1) The Cv value of the flow intensity of different vegetation spatial positions is between 10.26% and 15.50%,and the fluctuation of the runoff intensity is small. The runoff intensity of position A and the runoff of position B and position F were small. The intensity showed a significant difference (p<0.05),and the Cv value of the sediment yield in different vegetation spatial positions were above 26.00%. The sediment yield intensity of the position A showed significant difference with sediment yield of other positions (p<0.05). The effect of laying grass strips on the slope on the sediment production process was greater than the impact on the runoff process. (2) After planting vegetation on the upslope of the convex slope,the total runoff yield was reduced to a different extent compared with the bare slope (Position A),and the water reduction benefit of the position F was 19.65%. The sediment yield reduction benefit of position B was as high as 70% or more. (3) The average value of the average weight diameter (MWD) of sediment particles in different vegetation spatial position was: Position A > Position F > Position D > Position E > Position C > Substrate > Position B,the mean value of MWD gradually stabilized and approached the substrate with the prolongation of runoff generation time. Under the condition of hydraulic erosion with vegetation coverage,the erosion particles were mainly fine grains,the content of powder grains was higher,and the content of sand was relatively small. The farther the vegetation was from the top of the slope,the easier it was to erode 0.002~0.05 mm of powder. This study will help to deepen the understanding of the spatial distribution of vegetation on the mechanism of convex slope erosion and sediment production.

Abstract:In order to analyze the effect of air-permeable and water-proof soil on water infiltration and solute transport,an one-dimensional vertical soil column infiltration test was carried out with different bulk densities (1.40,1.45,1.50,1.60 g/cm³). The results showed that the air-permeable and water-proof (weak permeable) buried body could increase the cumulative infiltration of soil and promote the migration of wetting front. In a certain range,with the increases of the bulk densities of the air-permeable and water-proof (weak permeable) buried body,both the infiltration rate and the migration rate of wetting front increased. When the infiltration time was 600 min,the cumulative infiltration of soil increased by 7.42%~29.17%,and the depth of wetting front reached 27 cm. The infiltration time decreased by 26.97%~64.27% correspondingly. Compared with the control group,the amount of solute migration to the deep soil was reduced by different bulk densities of the air-permeable and water-proof (weak permeable) buried body. Both Philip model and algebraic model could describe the infiltration process of soil water in the air-permeable and water-proof (weak permeable) buried body,and the permeability s in Philip model and the comprehensive shape coefficient α in the algebraic model were positively correlated with the volume weight ratio and the volume weight ratio inside and outside the air-permeable and water-proof (weak permeable) buried body. The results showed that the air-permeable and water-proof (weak permeable) buried body could improve the water infiltration capacity and solute transport by changing the suction distribution of the upper soil,and realize the regulation and purification of urban rainwater runoff.

Abstract:In order to explore the impact of vegetation restoration on the water conservation function of litter layer and soil layer in degraded red soil region,and further reveal the functional effects of vegetation restoration in degraded ecosystems,water holding capacity of the litter layer and the 0—20 cm soil layer of three recovery modes (Schima superba Gardn. et Champ. pure forest,Pinus massoniana Lamb. pure forest,Pinus massoniana Lamb. replanted with Schima superba Gardn. et Champ) were measured by indoor flooding and cutting ring methods. The results showed that: (1) Pure Pinus massoniana. forest had the maximum litter accumulation (7.91 t/hm²) and water holding capacity (15.39 t/hm²),but lower maximum water holding rate than that of Schima superba. pure forest (246.69%).(2) The effective and the maximum storage capacity of litter layer in pure Pinus massoniana forest was the largest (7.75,and 10.02 t/hm²,respectively),while the smallest (3.83,5.36 t/hm²,respectively) was found in Schima superba pure forest. (3) The relationship between water holding capacity of litter layer and the immersion time followed the logarithmic function Q=aln(t)+b,R²>0.90; while the change of water holding rate of litter with the time of immersion fit the power function: V=at^b,R²>0.95,and the fitting is better. (4) The averaged maximum water retention of 0—20 cm soil layer in Pinus massonian are planted with Schima superba,Pinus massoniana pure forest and Schima superba pure forest were 10.49 mm,9.83 mm,and 8.28 mm,respectively. The mean value of soil maximum water absorption and storage capacity was higher in Schima superba (38.39 mm) than those in Pinus massoniana replanted with Schima superba (31.13 mm) and Pinus massoniana (30.35 mm). Therefore,it could be inferred that Pinus massoniana pure forest had the largest water conservation capacity,followed by Pinus massoniana replanted with Schima superb and then Schima superba pure forest. In the degraded red soil area where soil erosion is more serious,Pinus massoniana can provide a compromise solution for reducing soil erosion through the surface litter layer.

Abstract:Purple soil sloping farmland is an important cultivated land resource in southwest China. In order to explore the influence of soil management measures on the quality of eroded arable cultivated-layer of purple soil sloping farmland,the purple soil sloping farmland cultivated-layer soil is used as the research object,the soil erosion simulation plot was used to establish different erosion degree (erosion years) of sloping farmland location test,fertilizer management measure (F) and chemical fertilizer + biochar management measure (F + B) are set up,taking no fertilizer as a control (CK).Soil quality index method is used to analyze and evaluate the quality recovery effect of eroded cultivated-layer on purple soil sloping farmland and characteristics of indicator change with different management measures. Results show: (1) The effects of the two management measures on the physical and chemical properties of the soil cultivated-layer of purple soil sloping farmland were significant. F management measure can not improve soil structure,but can improve soil nutrient. Under B+F management measure,soil bulk density is minimal,soil total pores,capillary pores and saturated water content increase,and organic matter content is the highest,12.45 g/kg. Soil nutrient status is best. (2) Both F and B+F management measures can improve the shear strength of 0-10 cm soil layer,which makes the surface soil resist shear failure,which is conducive to soil erosion control,and the soil penetration resistance decreases under the other two management measures. Promote the growth and development of crop roots. (3) The two management measures improved the soil quality of the cultivated-layer of purple soil sloping farmland. The soil quality index was B+F (0.686),F(0.625) and CK(0.595),and the soil quality of B+F management measure was higher. Compared with CK (0.595),it increased by 15.3%,which was 9.8% higher than F (0.625). B+F management measure had the best effect on soil quality improvement of sloping farmland. B+F management measures can effectively improve soil structure and increase soil nutrient content,which is more suitable for quality restoration of cultivated-layer and soil erosion control in purple sloping farmland. The research results can provide suitable management measures for quality restoration of eroded cultivated-layer in purple soil sloping farmland. It is of great significance for the sustainable use of purple soil sloping farmland.

Abstract:The effects of zinc fertilizer and lime on double-season rice yield and soil nutrient characteristics were evaluated in a typical double-season rice growing area in southern China,in order to propose the best fertilization mode for fertilizing local soil and increasing rice yield. It is equipped with organic fertilizer + inorganic fertilizer (T1),zinc + organic fertilizer + inorganic fertilizer (T2),lime + organic fertilizer + inorganic fertilizer (T3),zinc + lime + organic fertilizer + inorganic fertilizer (T4),a total of 4 treatments. The indicators of soil available zinc,alkali nitrogen,available zinc,and pH were determined,and rice yield and soil comprehensive fertility were analyzed. The results showed that: (1) Compared with T1 treatment,T2 treatment significantly increased the 1000-grain weight and seed setting rate of early and late rice,and significantly increased yield by 8.7%. However,the application of lime (T3) in successive years was not conducive to stable yield of rice,significantly reduced 1000-grain weight,and significantly reduced yield in the second year (5.6%). The yield pattern exhibited by the T4 treatment was similar to that of the T3 treatment,and both showed a reduction in production in the second year. (2) The application of zinc fertilizer and lime was beneficial to increasing the content of available phosphorus and alkali nitrogen in soil. Lime could also significantly increase soil pH,but the effective zinc content in T3 and T4 treatments decreased significantly,which was 39.0% and 31.9% lower than that of T1 treatment. However,the application of zinc fertilizer for several years was conducive to the improvement of effective zinc. The effective zinc content of T2 was 22.2% higher than that of T1 treatment. (3) The soil comprehensive fertility was T2 > T4 > T1 > T3,the application of zinc fertilizer was more conducive to improving soil fertility than lime. In summary,the application of zinc fertilizer can significantly increase the soil available nutrient content,and increase production. However,the application of lime in successive years significantly reduced the effective zinc content in the soil. Therefore,lime should be applied cautiously in zinc-deficient soil,and for the long-term application of lime,attention should be paid to the supplement of exogenous zinc fertilizer. Based on comprehensive evaluation of soil nutrient content and rice yield,the fertilization mode of organic-inorganic + zinc fertilizer is the best fertilization mode.

Abstract:Using precipitation,air temperature,and runoff data from Xilinhot Meteorological Station and Hydrological Station from 1982 to 2018,the meteorological and hydrological drought index was calculated,and cross-wavelet analysis,cumulative anomaly,and run length theory were used to explore the hydrological drought evolution characteristics and leading factors in the Xilin River Basin. The results showed that from 1982 to 2016,the rainfall and potential evapotranspiration in the Xilin River Basin increased year by year,while the runoff depth showed a decreasing trend in each year. Due to the high drought level in upper reaches of Xilin River Basin in summer and winter,and the continuous drought in summer and winter since 2000,the high temperature and low temperature were the important reasons that may cause drought in the Xilin River Basin. Cross wavelet analysis found that the lagging relationship between meteorological drought and hydrological drought will be somewhat change,not all regions show that hydrological drought lags behind meteorological drought. The impact of human activities and climate change on the occurrence of hydrological drought in 1990—1998 and 1999—2016 was 67.7%,55.6% and 32.3%,44.4%,with a decreasing trend year by year.

Abstract:In order to solve the problems of the small lateral diffusion range of water in the soil and the leaching of nitrate nitrogen,the water regulator DY-ET100 was used as the test material,with the water and thirst as a control. The effects of nitrogen addition on the diffusion of water in different types of soil and nitrate nitrogen leaching and tomato yield and quality were studied. The results showed that the addition of moisture regulator DY-ET100 to sand-doped and non-sand-doped clay significantly increased the VC contents of tomato fruits by 12.50% and 20.51%,respectively. The treatment with DY-ET100 resulted in the more evenly distribution of water in soil of the 0~30 cm distance from the dripper. The water diffusion radius during drip irrigation were 22.53% and 12.33% higher than that of clear water and thirst. The accumulation of nitrate nitrogen in sand-doped and non-sand-doped clay was increased by 41.21% and 18.83% respectively compared with the water treatment. At the same time,the leaching loss of nitrate nitrogen was reduced by 7.53% and 8.07% respectively in sand-doped and un-sand-doped clays compared with the water treatment. This study provided data support for the promotion of water regulators.

Abstract:A field experiment was conducted to study the effects of regulated deficit irrigation on growth dynamics,yield and water use efficiency of Isatis indigotica under mulched drip irrigation in 2019 at Hexi oasis cold irrigation area of Yimin irrigation experimental station,Minle County. Under the condition of ensuring adequate water supply in seedling stage,full water supply in whole growth stage (75%~85% field water capacity) was taken as the control treatment. Mild,moderate and severe water deficit management was carried out in the vegetative stage,mild and moderate water deficit treatment was carried out in the fleshy root growth stage,and mild water deficit treatment was carried out in the fleshy root maturity stage. The periodical changes in agronomic traits,dry matter accumulation and distribution,yield and water use efficiency of I. indigotica were measured under different water deficit treatments. The results showed that the plant height,taproot length,taproot diameter and leaf area index of I. indigotica decreased significantly (P<0.05),on moderate and severe water deficit during vegetative stage and fleshy root growth stage and light water deficit during fleshy root maturity stage. There was no significant difference in plant height,taproot length,taproot diameter,and leaf area index with the control treatment between the vegetative stage and fleshy root growth stage under mild water deficit treatment (P>0.05). Moderate water deficit and severe water deficit in vegetative stage and fleshy root growth stage could reduce dry matter accumulation of I. indigotica. The decrease ranged from 3.11% to 15.67%. Mild water deficit treatment would not significantly affect dry matter accumulation. There was no significant difference between the economic yield of WT1 and WT4 with control treatment (P>0.05). Their values were 8 554.18 kg/hm² and 8 398.70 kg/hm². All other treatments reduced the economic output of I. indigotica. The decrease ranged from 6.89% to 18.33%. Water use efficiency (WUE) and irrigation water use efficiency (IWUE) in WT4 were the highest. Compared with the control treatment,it was improved by 7.91% and 7.39%. Therefore,applying continuous mild water deficit during the vegetative stage and the fleshy root growth stage and providing adequate water supply during the other growth stages is an optimal irrigation method with high efficiency,water saving,and high yield in the irrigation area of Hexi oasis cold irrigation area.

Abstract:To uncover the effect of mulched drip irrigation under water deficit on the yield and quality of onion in Hexi corridor,a field experiment was conducted taking "Hongbao 903" as study object. The experimental employed a two-factor randomized blocks design of mulched drip irrigation with different water deficit gradients in growth periods,which included nine treatments totally. Onion photosynthetic parameters in every growth period were measured,and the onion productivity and quality were determined after harvest. Results showed that: (1) Water deficiency (WD) in the development and bulbification stages obviously decreased net photosynthetic rate,transpiration rate and intercellular CO₂concentration,and the reduction increased with the raise of water deficiency. (2) WD decreased yield in different degree. Slight water deficit in ripening stage was the highest (47 940 kg/hm²),secondly in the establishment satge (46 521 kg/hm²),of which decreased by 5.93% and 8.71% (P>0.05) respectively compared with full irrigation. (3) Slight water deficit in the establishment period gave the highest irrigation efficiency (58.84 kg/m³),secondly in ripening stage (52.60 kg/m³),of which increased by 36.14% and 21.70% respectively compared with full irrigation. (4) The onion quality was the best under the treatments of slight water deficit in the establishment stage,indicated by the increased compactness,onion oil,soluble sugar,soluble protein,vitamin C and pyruvic acid,by 3.06%,2.50%,10.40%,17.57%,4.35% and 6.06% respectively,compared with full irrigation. Taking the productivity,water product efficiency,output value and fruits quality,etc. altogether,the principal component analysis was used for comprehensive evaluation. The slight water deficit in the establishment stage was an ideal stage for soil moisture regulation. There lative soil water content should be kept around 70%~75% in the establishment stage,and 80%~85% in others. These results could provide the theoretical and technical references for the water saving planting ofonion and its industrialization development.

Abstract:In order to provide a theoretical basis for high-quality,high-yield,and high-efficiency planting of edible sunflower in the cold-cool irrigation area of Hexi Oasis,a field trial of edible sunflower with drip irrigation deficit adjustment under film mulch was conducted in 2019,Zhangye City Yimin Irrigation Experimental Station to explore the influence of adequate irrigation at the bud,flowering,and grouting stages treatment,the seedling stage (mild) — maturity stage (mild and Moderate) water deficit treatment,the seedling stage (moderate) — maturity stage (mild and moderate) water deficit treatment,and the seedling stage (severe) — maturity stage (mild and moderate) water deficit treatment on water consumption,photosynthesis,quality,and yield of edible sunflower. The results showed that: (1) The water consumption,water consumption modulus,and daily water consumption intensity of edible sunflowers at the seedling stage and the mature stage decrease with the increase of water deficit. Compared with full irrigation,the water consumption,water modulus,and daily water intensity in the seedling stage decreased by 10.10%~46.08%,7.57%~34.58%,10.68%~46.60%,and in the maturing stage decreased by 5.50%~30.29%,2.93%~16.72%,5.56%~30.34%. The compensation effect of severe water regulation deficit during the later period was limited. (2) Severe water deficit at seedling stage and moderate water deficit at maturity stage significantly reduced net photosynthetic rate,stomatal conductance,and transpiration rate of edible sunflower leaves. Compared with full irrigation,the declines of severe water deficit adjustment at seedling stage were 40.30%~45.98%,43.99%~47.37%,38.20%~42.10%,the declines of moderate water deficit adjustment at maturing stage were 14.23%~32.07%,15.98%~51.23%,10.02%~28.45%.(3) The quality of mild water deficit in seedling stage—moderate water deficit in maturing stage was the best,and its crude fat content and crude protein content were 10.84% and 14.90% higher than those of full irrigation. (4) The yield of mild water deficit in seedling stage—moderate water deficit in maturing stage was 4145 kg/hm²,which is at the same level as the control CK. The yield was not significantly reduced. The treatment had the function of saving water and regulating quality. Taking indicators such as water consumption,photosynthetic characteristics and quality of edible sunflowers into account,under the conditions of full irrigation in other growth periods,moderate water deficit adjustment at the seedling stage and mild mature stage was adopted as the optimal water-saving deficit irrigation mode for local sunflowers.

Abstract:Using water balance method combined with GIS spatial analysis and linear regression method,this paper evaluated the water conservation functions of various ecosystems,basing on which the definition of the ecological protection red line was discussed. Results showed that: (1) Water conservation capacity was higher in the southern Shaanxi,followed by that in the north and central Shaanxi. Annual water conservation per square kilometer fluctuated between 0~800.90 mm,with significant spatial difference. From 2000 to 2014,the total water conservation capacity increased significantly and the area with increasing water conservation rose to 86.71% of the total area,and the total water conservation capacity characterized by "overall rise and partial decline". (2) Strong relationships were detected among climatic elements and water conservation. Meanwhile,the vegetation types also played certain roles in affecting the spatial patterns of water conservation. Among vegetation types,forest was the major contributor to the water conservation function in this region. The order of water conservation capacity in terms of forest ecosystems was evergreen broad-leaved forest > evergreen coniferous forest > deciduous broad-leaved forest > deciduous coniferous forest. (3) In the study area,the area with unit water conservation less than 200 mm accounts for 65.12% of the total area,indicating insignificant overall water conservation value. The red line areas of water conservation and ecological protection is comprehensively delimited to approximately 77 593.31 km²,37.70% of the total area,which was mainly distributed in the mountainous areas of the central and western Qinling Mountains,southern Hanshui Valley and northern Yanhe River Basin.

Abstract:The objective of this study was to explore whether the integration of row spacing ratio with planting density in one cropping system will increase water use efficiency of ‘Wugu 568’ maize at the Oasis Irrigation District. A field experiment was conducted at the Oasis experimental station from 2017 to 2018,to investigate the above objective. Three row spacing levels were used in the ratio; 7∶3 (L₁,56 cm wide∶24 cm narrow),6∶4 (L₂,48 cm wide∶32 cm narrow),and 5∶5 (L₃,equal row spacing 40cm); with five plant density levels,thus,82 500 plants / hm² (D₁),90 000 plants / hm² (D₂),97 500 plants / hm² (D₃),105 000 plants / hm² (D₄),112 500 plants / hm² (D₅). The primary objective of this research was to investigate the effect of different row spacing ratio and planting densities on water consumption,grain yield and water use efficiency of maize. The results showed that row spacing ratio of L₁ can effectively reduce the water consumption and increase the evaporation between rows and has no significant effect on E/ET. Among the treatments,L₁ can effectively reduce water consumption by 11.9% compared with L₃ in 2017,and there was no significant difference in 2018. Comparing the row spacing ratio,the L₁ row spacing ratio has the advantage of increasing grain yield by 5.2%~10.5%,and improving water use efficiency by 6.5%~8.7%. By comparing the density treatments,D₃ density can effectively reduce water consumption and the evaporation between rows,and E/ET as compared to the traditional density D₁. The treatment D₃ is 13.3% lower than that of the traditional density D₁ and promoted and increased corn yield and water use efficiency. In 2018,the difference was not significant; the evaporation between rows decreased by 7.1%~7.2%; E/ET decreased by 6.8%~ 19.2%; increased grain yield by 7.5%~17.1%; and also increased water use efficiency by 23.9%~ 46.2%. Comparing the traditional treatment L₃D₁ water consumption to L₁D₃ in two years,it reduced by 12.8%~30.6%. The evaporation between rows reduced by 8.5%~10.4%; E/ET reduced by 7.3%~7.5%; water use efficiency improved by 36.0%~41.2%,and increased the grain yield by 7.7%~25.5%. Therefore,7∶3 (L₁,56 cm wide∶24 cm narrow) row spacing ratio combined with 97 500 plants / hm² (D₃) plant density can effectively increase maize yield and improve maize water use efficiency in Hexi oasis irrigation area.

Abstract:To explore the effect of returning crop straw to the field structure improvement. In this experiment,we adopted in two factor split plot design that of main factor fertilization (F): F1 (NPK compound fertilizer),F0 (no fertilizer); and that of the auxiliary factor crops (B): B1 (rape),B2 (corn),B3 (potato),B4 (oats),B5 (buckwheat). Unplanted and without fertilization used as the control (CK). We measured several parameters that of soil bulk density,porosity,capillary porosity,field water holding capacity,aggregate size and MWD,GMD,D values. The results showed that straw mulching of 5 crops reduced soil bulk density,increased capillary porosity and field water retention in 0—60 cm soil layer,and 20—60 cm soil layer was the main improvement. At the same time,the content of soil >0.25 mm granular aggregates was increased,and the MWD and GMD values of aggregates in the 0—20 cm soil layer were increased,while the D values were decreased and the stability was increased. When straw was returned to the field with chemical fertilizer,the content of >0.25 mm granular aggregates in 0—60 cm soil decreased,MWD and GMD values decreased,and D values increased,and the stability decreased. We confirmed that rape straw returned treatment would improving soil density,porosity,filed water-holding capacity and aggregate stability,buckwheat straw returned treatment would increasing filed water-holding capacity,oat straw returned treatment would increasing soil aggregate stability. We concluded that returning crop straw to field would improving the soil structure and achieved different effects to differ crop types. In general,the rape straw returning to field is better improvement for soil structure.

Abstract:Soil moisture is an important factor restricting agricultural development in arid and semi-arid regions of northwest China. It is of great theoretical and practical significance to explore a scientific and reasonable relationship between nitrogen fertilizer,water and yield for promoting the sustainable development of regional agriculture. At the Changwu Loess Plateau Agro-ecological Experiment Station of the Chinese Academy of Sciences in Changwu County,Shaanxi Province,a nitrogen fertilizer decline test was performed. Based on the traditional nitrogen application of 250 kg/hm² (N6),it was reduced by 20% in order. Set CK,N1,N2,N3,N4,N5,N6 seven processes. The results showed that: (1) The soil water consumption during the growth period of spring corn increases with the increase of nitrogen fertilizer application. The soil water deficit mainly occurs below 80 cm of soil layer,and the degree of water deficiency increases with the increase of nitrogen fertilizer application. (2) Both the yield and water use efficiency of spring corn showed a second parabolic trend with the increase of nitrogen fertilizer use. The traditional nitrogen application rate of spring corn (N6,250 kg/hm²) has been severely excessive,and a reduction of 20% (N5,nitrogen application rate of 200 kg/hm²) can achieve higher yield and water use efficiency. Compared with N6,N5 grain output increased by 9.6% and 5.8%,and water use efficiency increased by 14.5% and 9.1%. Therefore,it is recommended to reduce nitrogen by 20% (N5,200 kg/hm² nitrogen application rate) as the recommended nitrogen application rate.

Abstract:In order to provide a scientific basis for the cultivation and breeding of wheat and the improvement of nitrogen utilization in central Shandong. "Tainong 18" "Linmai 4"and "Wennong 5"which are three high-quality wheat varieties with a wide cultivation area in central Shandong were selected and three nitrogen levels of 0,120,240 kg/hm² were set to study the response of yield and nitrogen utilization of different wheat varieties to nitrogen application rate with field experiment for 2 years. The results showed that the application of nitrogen fertilizer could increase the synthesis and accumulation of photosynthetic pigments in wheat leaves,promote photosynthesis,increase the dry matter accumulation of wheat and its transport to grain,facilitate the construction of wheat population and promote the formation of yield. The yields of three wheat varieties at the N120 and N240 level respectively increased by 0.67~2.10 times and 0.97~2.62 times compared with the N0 level. With the increase of nitrogen application rate,the responsiveness of wheat to nitrogen fertilizer decreased,nitrogen absorption and utilization efficiency,nitrogen fertilizer partial productivity and agronomic efficiency were significantly reduced. Variety differences have significant effects on wheat growth and yield formation. In this study,all indicators of wheat showed "Tainong 18" > "Linmai 4" > "Wennong 5". "Tainong 18" had the highest yield and better nitrogen absorption and utilization ability. "Wennong 5" was the most sensitive to nitrogen. Compared with "Linmai 4" and "Wennong 5",the yield of "Tainong 18" increased by 15.83%~26.42% and 34.50%~42.43% respectively under the N0 level,increased by 4.97%~5.05% and 12.23%~12.54% respectively under the N120 level,increased by 4.13%~5.75% and 8.49%~11.08% respectively under the N240 level. In summary,the optimum nitrogen application rate in central Shandong is 240 kg/hm² under the conditions of this experiment,"Tainong 18" is the most suitable wheat variety for promotion,and "Wennong 5" has great potential for increasing yield which can provide a scientific basis for wheat variety selection.

Abstract:The effects of green manuring rotations in summer fallow period on soil water and water use efficiency (WUE) in winter wheat were studied in extremely dry year during wheat growth period in different altitude-regions by large-scale field comparing method. The results showed that the soil water storage was higher at sowing date and mature date of wheat under different green manuring rotations at altitude of 998 m than that at 495 m,and the soil water storage difference in 0—100,100—200,and 200—300 cm was extremely significant between two altitudes,respectively. The soil water storage was decreased with green manuring date delay on same rotation in 0—100 cm and 100—200 cm at sowing date at all altitudes. The soil water storage difference in 0—100,100—200,and 200—300 cm was extremely significant,significant,and not significant between sowing date and mature date,respectively. The soil water storage proportion of mature date to sowing date was increased with soil layer increasing in 0—100,100—200,and 200—300 cm at altitude of 998 m,while the proportion was higher in 100—200 cm than that in 200—300 cm at altitude of 459 m. During wheat whole growth period in same green manuring stubble between high altitude and low altitude,soil water consumption showed extremely significant difference in 100—200 and 0—200 cm,significant difference 0—100 cm and 0—300,and no difference in 200—300 cm. The soil water consumption of different layer was correlative with the soil water storage in wheat sowing stage of same green manuring stubble at two altitudes. The wheat yield and water use efficiency at 998 m altitude were higher than those at 495 m in same green manuring stubble. The yield difference was extremely significant,while the water use efficiency showed no difference. The early corn green manuring stubble and deep tillage stubble had higher water use efficiency at 998 m and 495 m. The study provided theoretical foundation and technical support for improving farmland quality and soil water bearing capacity by green manuring in different regions.

Abstract:In order to reveal the application effect of machine-transplanting with side-deep fertilization of controlled-release blended fertilizer in the southern double cropping rice. Field experiment was conducted for early- and late-rice,and 4 treatments were set up: no nitrogen (N) fertilizer application,conventional fertilization,machine-transplanting with side-deep fertilization by reducing N of 30% and machine-transplanting with side-deep fertilization of controlled-release blended fertilizer by reducing N of 30%. The objective of this study was to compare the effect of machine-transplanting with side-deep fertilization of controlled-release blended fertilizer and conventional fertilization on yield,economic benefits and nutrient uptake and utilization of double-cropping rice,and its reducing potential. Results showed that the yield and economic benefit of machine-transplanting with side-deep fertilization reduced N by 30% of early-rice is higher than those of conventional fertilization by 20.2%~20.9% and 31.8%~32.4%,and its effective panicle,total spikelet and total grain increased by 6.2%~7.5%,20.5%~25.3%,and 27.6%~28.2%,respectively. The yield and economic benefit of machine-transplanting with side-deep fertilization reduced N by 30% of late rice increased by 3.9%~5.2% and 12.6%~13.8%,and its effective panicle,total spikelet,and total grain increased by 15.8%~17.8%,16.8%~18.6% and 14.0%~16.8%,respectively. Hence,the effect of the reduction of side-deep application of controlled-release blended fertilizer is better. Under the condition of machine-transplanting with side-deep fertilization with a N reduction of 30%,the N,P and K uptakes of early-rice with controlled-release blended fertilizer compare with conventional fertilization reduction at harvest time increased by 1.6%,2.5% and 7.9%,respectively,and those of late rice increased by 4.0%,1.1% and 0.9%,and those of early- and late- rice were increased in N recovery efficiency by 4.2% and 10.2%,in N agronomic efficiency by 3.3% and 1.2%,in N partial factor productivity by 0.6% and 1.2%. In conclusion,in the Dongting Lake area,machine-transplanting with side-deep fertilization of controlled-release blended fertilizer can effectively reduce N fertilizer application in the rice field,facilitate the formation of effective panicle,improve N,P,K accumulation and N fertilizer use efficiency,reduce N loss,and thus realize the production of double-cropping rice in terms of saving fertilizer,saving labor,increasing efficiency and increasing yield.

Abstract:Aiming at the problems of coastal saline soil paddy soil root growth under saline-alkali stress,low nutrient content and low availability. In this research,field experiment was conducted to studythe effects of combined application of phosphate fertilizer and silicon fertilizer on rice root growth,soilphosphorus content,the rice absorbs phosphorus,riceyield,and economic benefits of rice in coastal saline soil. The experiment has twofactors,including two phosphoruslevels: P1: 64 kg/hm²; P2: 128 kg/hm²; silicon fertilizer is divided into soil application and spray application,three levels of soil application:Si1,SiO₂ 0 kg/hm²,Si2,SiO₂ 60 kg/hm²; Si3,SiO₂ 120 kg /hm²; Spray is SiO₂ 15 kg/hm²,and applied with water-soluble multieffect silicon fertilizer (containing water-soluble SiO₂≥30%),which was diluted 500 times per 100 mL and sprayed with 50 L per hectare.The results indicate that the P2Si3 treatment’s total root length,total surface area and total root volume of rice were significantly higher than each other period andit was no significant difference with P2Si4 treatment. Meanwhile,phosphate fertilizer combined with silicon fertilizer can effectively improve the availability of phosphorus in coastal salinized rice soil,the content of available phosphorus in P2Si3 treatment was significantly higher than that in P1Si3 and P2Si1,respectively higher 35.16% and 27.47%; the total phosphorus content of soil treated with high phosphorus fertilizer was higher than that treated with low phosphorus fertilizer. Moreover,rice yield with P1Si3 and P2Si4 treatment was significantly higher than that P1Si1 and P1Si2 treatment,the yield of P2Si3 treatment was 9 547.5 kg/hm² there was no significant difference in the effective spike number of each treatment,P2Si3 treatment was the highest with 162.47 grains per panicle. P2Si3 treatment’s accumulation of p in rice grains and was significantly higher than other treatments,compared with P1Si3 and P2Si1,it was 8.46% and 9.68% higher respectively. Under low or high phosphorus level,P1Si4,P2Si4 treatment’s income reached 14 953.6 CNY/hm² and 14 323.2 CNY/hm².In conclusion,compared to the treatment without silicon fertilizer,the application of silicon fertilizer can significantly promote the root growth of rice,phosphorus availability,rice yield and economic benefit in coastal salinized soil,among them,P2Si3 treatment (silicon sprayed on the blade,P₂O₅ 64 kg/hm²) is the best treatment.

Abstract:NBPT (n-butyl thiophosphoryltriamide) and DMPP (3,4-dimethylpyrazolphosphate) were used as composite inhibitors. By optimizing the combination and using the drum spray process,a new type of composite inhibitor coated urea fertilizer was developed. The effect of coating was analyzed by SEM and EDS. Field experiments were conducted to systematically evaluate the effects of different nitrogen topdressing on nitrogen regulation. Five treatments were set up: (1) No N application (CK); (2) farmers’ habit of applying urea (CU); (3) optimization of applying urea (CUU); (4) optimization of applying inhibitor coated urea (CUY1); (5) optimization of applying inhibitor coated urea (CUY2). The field in-situ continuous dynamic observation was carried out within 15 days after applying urea at the ten leaf stage of summer maize and jointing stage of winter wheat. The composite inhibitor was uniformly coated on the surface of urea to form a thin,compact and smooth coating layer. The coating layer was evenly distributed with phosphorus and sulfur elements,which indicated that the composite inhibitor and urea had effectively combined. Compared with the common urea after the same N application,the ammonia volatilization of CUY1 and CUY2 in summer maize and winter wheat decreased by 55.19%,32.15% and 52.46%,39.43% respectively. After topdressing in summer maize season,the content of soil NO₃^--N in 0-20 cm soil lager in CU and CUU treatment reached the peak value at the 5th day,which was significantly higher than that of CUY1 and CUY2 treatment at the same period,and significantly lower than that of CUY1 and CUY2 treatment at the later stage. According to the trend of CUY1 treatment,the effect of CUY2 treatment on stabilizing NO₃^--N in 0-20 cm soil layer is better. After topdressing in winter wheat season,the content of soil NO₃^--N in CU and CUU treatment reached the peak value on the 5th and 3rd day,respectively. The content of soil NO₃^--N in CUY1 and CUY2 treatment increased slowly,and reached the peak value on the 11th day,which was 38.64%,36.08% and 43.65%,48.19% respectively lower than that of CU and CUU treatment. After the 11th day,the content of NO₃^--N was significantly higher than that of CUU with the same N application. At the same time of ensuring the yield and net income,urea coated with inhibitor significantly reduced the ammonia volatilization and leaching loss concentration of nitrogen,among which CUY1 treatment on winter wheat had better economic benefit,CUY2 on summer maize had the best effect of regulating nitrogen,and the effect of reducing leaching down was obvious.

Abstract:In order to evaluate the enhanced effect of soil organic carbon (SOC),total nitrogen (TN) and available nitrogen (AN) concentration under short-term restoration measures in erosion-degraded lands,we adopted the random stratified sampling strategy based on the theory of minimum detectable change (MDC),to eliminate spatial variability of SOC and nitrogen overtime. A typical erosion degraded forestland was selected,which located in the hilly red soil region of south China. 7 treatments were set up in this trial: No restoration measures (CT),tree and grass + fish scale pit (FG),tree and shrub + fish scale pit (FS),tree,shrub and grass + fish scale pit (FGS),tree and grass + small horizontal ditch (FGP),tree and shrub + small horizontal ditch (FSP),tree,shrub and grass + small horizontal ditch (FGSP). The results suggested that the vegetation coverage of each treatment increased significantly compared with those before the experiment,and the increase range was 7% to 50% after 18 months. Especially,the grass and shrub coverage significantly increased under each restoration measures. Except for FG and FS treatments,changes in SOC can be detected in all other treatments; except for FG treatment,changes in TN can be detected in all other treatments,while changes in AN can be detected in all treatments. The increase ranges of SOC,TN and AN content under each restoration measure were 0.10 to 2.08 g/kg,0.02 to 0.13 g/kg and 8.54 to 25.06 mg/kg,when compared with those before the experiment. The ranges of net increment of SOC,TN and AN were 34% to 101%,35% to 83% and 14% to 82%. The net increment of SOC in different treatments were in decreasing order of FGSP > FG > FGP > FGS > FSP > FS,while the net increment of TN showed as FS > FGS > FGSP > FGP > FSP > FG. The increment of SOC,TN and AN content in small horizontal ditch groups were significantly higher than those in fish scale pit groups. Near-surface grass and shrub vegetation coverage,is a key factor affecting changes in contents of SOC,TN and AN under erosion degraded forestland of red soil region. Local pioneer shrub plus grass with soil conservation engineering practices were the effective restoration measures for red soil erosion-degraded forest hillslope land and the improvement of SOC and nitrogen in the short term.

Abstract:In order to study the effects of granulated straw (JG) and fungus residue (JZ) amendments (6,12,18,24 t/hm²,respectively) on soil carbon pool of alpine sandy land in northwest Sichuan,a field location experiment was conducted. The results showed that the application of JG and JZ amendments could significantly improve the organic carbon,organic carbon storage,activated carbon,soil microbial biomass carbon,microbial entropy and carbon pool management index of desertification soil,and the enhancement effect on soil microbial biomass carbon and microbial entropy was the most significant. Compared with CK,the soil organic carbon,organic carbon storage,active organic carbon,and carbon storage management index of JG increased by 96.2%,100.0%,157.1%,169.4% on average,while those of JZ treatment increased by 69.2%,66.3%,85.7% and 81.7% in the second year after application amendments. Compared with CK,the microbial biomass carbon and microbial entropy of JG increased by 934.0%,433.0% respectively,while the microbial biomass carbon and microbial entropy of JZ increased by 956.2% and 546.4% on average. JG amendment had a better effect on the improvement of soil organic carbon storage components and carbon pool management index than JZ,while JZ amendment was beneficial to the improvement of soil microbial biomass carbon content and soil organic carbon turnover rate. Both granulated straw and fungus residues could increase the component content of soil organic carbon pool and improved the turnover rate of soil organic carbon and carbon pool management index,which also could fertilize the sandy soil rapidly.

Abstract:In order to investigate the relationship among soil organic carbon and small environment and lithology in different karst landforms that the Karst plateau (KG),Karts peak-cluster depression (KF),Karst canyon (KX),Karst virgin forests (KY) and Karst trough valley (KC) were taken from Puding,Xingyi,Guanling,Libo and Yinjiang in Guizhou province,respectively. The content of soil organic carbon in soil horizons (0-10,10-20,20-30 and 30-40 cm) and organic carbon in the critical surface between bottom soil layer and bedrock were was tested by the method of potassium dichromate,and then counting out the density and storage of Soil organic carbon,the spatial distribution characteristics of soil organic carbon in different karst landforms was analyzed. The results showed that the content,density and storage of soil organic carbon in different rocky desertification class were 113.18~163.98 g/kg,1.08~7.32 kg/m³ and 4.07~24.29 kg,respectively. The soil organic carbon is gradually reduce with the increasing of kasrt rocky desertification degree,and then the soil organic carbon concentration in stone trough is higher than other small environment types,and the content of soil organic carbon in the soil above on Limestone and Marl are more than other Lithology types as well. There is a large discrepancy of soil organic carbon among different karst landforms,in same ecology environment the soil organic carbon storage in KY and KC are more than other landform types. The soil organic carbon move along the evolution chain of Karst rocky desertification process,and the change of Small environment and Lithology in different karst landforms are play an important role in the spatial rebuild of soil organic carbon. The ecology environment of karst mountainous area is complex. If we want to get a more sensitive method to estimate the soil organic carbon in different karst landforms,further studies concerning soil organic carbon among different karst landforms were required.

Abstract:In order to understand the influence of ecological restoration models on the exchange and distribution of soil base ions in the karst mountain area,the typical yellow rendzina was taken as study object and the effects of ecological restoration pattern,which including arable land (AL),Grassland (GL),the intercropping system of forest and grass (ICS),and the grassland converted from cropland (CGL),on the cation exchange capacity (CEC) and the exchangeable base contents were studied. The results showed that the CEC vary between 26.52 and 44.90 cmol/kg and decreased with the increase of profile depth. CEC of each soil layer was significantly lower in CGL than in ICS,GL,and AL (P<0.05). The CEC of ICS was the highest in 0—10 cm and 10—20 cm soil layers. The size order of exchangeable base cations was Ca²⁺ > Mg²⁺ > K⁺ > Na⁺,and Ca²⁺,Mg²⁺ were the major exchangeable bases,because Ca²⁺,Mg²⁺,K⁺,and Na⁺ accounts for 91.92%,6.04%,1.03%,and 1.01% of the total content of exchangeable bases,respectively. The contents of Mg²⁺,K⁺,and Na⁺ were higher in the surface layer than those in deeper layers and decreased with the increase of soil depth regardless of restoration patterns. Under different ecological restoration modes,the content of each base ion in CGL was significantly lower than in ICS,Al and GL (P<0.05),but the content of each base ion varied with the soil depth. The distribution rule of soil total exchangeable base (TEB) was not obvious at the soil depth. The order of soil TEB in different ecological restoration modes was different with the increase of profile depth,in 0—10 cm,10—20 cm soil layer,and 40-60 cm (mother rock) layer,GL was the highest and CGL was the lowest. The soil base saturation (BS) in this area changed between 42.58% and 65.02% and gradually increased with the increase of soil depth. BS were the largest in GL,and followed by those in AL,ICS,and CGL. Correlation analysis showed that CEC,base ion content and organic matter,total nitrogen and alkaline nitrogen were all significantly and positively correlated. Redundancy analysis (RDA) shows that soil physical and chemical factors could only explain 45.3% of the changes in cation exchange. The changes in soil cation exchange were affected by other factors besides the basic physical and chemical factors. In general,CGL was significantly lower than other recovery models in the ability of fertilizer supply and buffer and GL had better performance. In the early stage of restoration,the soil fertility and buffer capacity decreased,but it will be improved gradually with the process of ecological restoration.

Abstract:In order to study the effects of the combined application of controlled-release urea (CRU) and controlled-release potassium chloride (CRK) on soil fertility and peony growth,and provide a theoretical basis for the controlled-release fertilizer (CRF) to replace traditional chemical fertilizers in peony large-scale cultivation,field experiments were arranged,normal urea with potassium chloride base-fertilizer and top-dressing which used by farmers was set as a control,fertilizers with different dosage of CRU (135,270,405 kg/hm²) and CRK (90,180,270 kg/hm²) were chosen,the effects of interactive one-time fertilization on soil nutrient supply capacity and peony growth of "Huang Cuiyu" variety were studied. The results showed that the cumulative nitrogen release rate of CRU reached 80% at 84 days in 25℃ still water extraction,and the release rate of CRK reached 80% at 112 days,which had superior stable and sustainable nutrient supply capacity. With the same amount of fertilization,compared with farmers' customary fertilization (Control),the content of nitrate nitrogen,ammonium nitrogen,and available potassium in soil 0—20 cm soil layer was significantly increased by 68.0%~157.8%,46.6%,and 16.1%~122.6%; the same amount of CRF treatment increased the peony plant height by 8.6%,the stem diameters were increased by 25.3%,the flowers per plant number increased by 25.1%. The CRU and CRK treatments had a significant interaction influence for the soil nitrate nitrogen content,peony leaves net photosynthetic rate,intercellular carbon dioxide concentration,and transpiration rate. The optimal amounts of CRU and CRK fertilization of this study were 270 and 90 kg/hm²,respectively. One-time application of CRU and CRK saves time and labor compared with customary fertilization,improves soil fertility,and promotes peony growth,which has higher promotion value in peony planting.

Abstract:Based on field experiment,the influence of controlled release urea (CRU) application on soil inorganic nitrogen distribution,nitrogen uptake and use characteristics of spring maize (Zea mays L.) was analyzed to provide theoretical basis and technical support for high-efficiency utilization of nitrogen fertilizer and high-yield maize in the southern mountain area of Ningxia. Xianyu 698 was used as experimental material. Five treatments that including No nitrogen was applied as the control (CK),conventional nitrogen supply UR (100% Urea (U),1/3 U base application,1/3 U flare opening period application),CRU1 (1/3 CRU + 1/3 U base application,1/3 U flare opening period application),CRU2 (2/3 CRU + 1/3 U base application),and CRU3 (100% CRU base application) were designed to explore the effects of CRU input on soil inorganic nitrogen distribution,nitrogen uptake,nitrogen use efficiency and yield of maize. The results showed that the soil nitrate nitrogen and ammonia nitrogen content in the mid-late stage of maize with the CRU treatments was significantly increased compared with those of UR treatment,with the highest increase in CRU2 treatment. CRU input could improve the yield and nitrogen utilization of spring maize. Compared with UR,the average yield of spring maize increased by 0.67 t/hm²,the nitrogen partial factor productivity (NPFP) increased by 2.92 kg/kg,and the nitrogen use efficiency (NUE) increased by 6.02%. Compared with CRU1 and CRU3 treatments,the yield,NPFP,and NUE in CRU2 treatment within two years were significantly increased by 0.10 t/hm² and 0.53 t/hm²,0.30 kg/kg and 2.23 kg/kg,2.49% and 9.44%,respectively,indicating that the positive responses of yield,NPFP,and NUE to CRU2 in all CRU treatments. Comprehensively,under reasonable distribution conditions,the blending of UR and CRU had a significant effect on increasing the soil nutrient supply and nitrogen absorption in spring maize. Therefore,we suggested that 2/3 CRU+1/3 U base application for rain-fed maize in Southern Ningxia.

Abstract:Based on two-year wheat/maize rotation field experiment on coastal salinized Fluvo-aquic soil,the effects of different soil amendments on soil aggregates distribution and stability,organic carbon content and the contribution rates of different size class aggregates to total organic carbon had been studied. The field experiment consisted of 3 treaments,no soil amendments (CK),organic soil amendments (OSA),and organic-inorganic compound soil amendments (CSA). Soil samples were collected for analysis of soil aggregates distribution,water-stable macro-aggregates (R_0.25),mean weight diameters (MWD),geometric mean diameters (GMD),fractal dimension (D),soil organic carbon storage (SOCS) and its distribution in aggregates. The results showed that the composition of soil aggregates in the coastal salinized Fluvo-aquic soil was dominated by <0.25 mm water-stable aggregates. The application of soil amendments significantly increased the number of large aggregates (>0.25 mm),and the effects on >5 mm and 2~5 mm aggregates were the highest among different aggregates. Compared with CK,the numbers of >5 mm and 2~5 mm aggregates under OSA treatment significantly increased by 167.38% and 59.00%,while those under CSA treatment significantly increased by 89.17% and 100.66%. The MWD and GMD were significantly increased under the OSA and CSA treatments,which suggested that the application of OSA and CSA increased the number and stability of large aggregates. The SOC content of all aggregates fractions under OSA and CSA treatments were higher than those under CK after two-year located trials,and the effects on 1~2 mm and 2~5 mm aggregates were the highest under the OSA and CSA treatment,respectively. As the application of soil amendments,SOC accumulated within macroaggregates,which has a relatively faster turnover rate. Compared with CK,the application of soil amendments significantly increased the contribution rate to the total SOC in >2 mm size of aggregate by 93.62%~109.76%,while it reduced or significantly reduced in <1 mm size aggregate by 20.55%~24.92%. Therefor,the application of soil amendments is the effective method to improve the stability of soil water-stable aggregates and increase the SOC content of macro-aggregates,as well as further promote the sequestration of organic carbon in wheat/maise rotation system.

Abstract:In order to achieve cost-effective synergy as well as alleviate the adverse environmental effects caused by large and multiple topdressing,the mid-late-maturing japonica rice "Yanfeng 47" as test material was used in this research,three experimental groups (conventional fertilizer,Zhongkehong stable compound fertilizer,and carbon-based fertilizer) and a blank control group were established to study the growth and nitrogen metabolism of rice treated with slow/controlled release fertilizers as well as their effect on yield. The results showed that there is no significant difference in yield when comparing the two slow/controlled release fertilizers against conventional fertilizer. The high yields of the Zhongkehong stable compound fertilizer group and conventional fertilizer group could mainly be attributed to a larger number of effective panicles,while carbon-based fertilizers increased yield due to the higher numbers of grains,higher seed set rate,and higher 1 000-grain weight. As for nitrogen metabolism,the two slow/controlled release fertilizers increased the activities of nitrate reductase (NR),glutamine synthase (GS),nitrite reductase (NiR),and soluble protein content in functional rice leaves during the heading stage,while glutamate synthase (GOGAT) activity was significantly higher when using conventional fertilizer compared to all other groups. Zhongkehong stable compound fertilizer contained nitrification inhibitors,urease inhibitors and other components that ensure a longer nutrient release cycle and improve nitrogen metabolism capacity during key stages of plant growth,especially toward the end of the heading stage in order to preserve the stem and increase the number of panicles. Carbon-based fertilizers employed biochar and other functional groups to improve soil nutrient retention and improved the extractable nutrient content and its effectiveness. Because of this,a balanced usage of Zhongkehong stable compound fertilizer and carbon-based fertilizer could reduce the amount of chemical fertilizer during stable rice production (reduction of 151.50,187.50 kg/hm² compared with conventional fertilizer) may have real-world value in the development of green sustainable agriculture cultivation in coastal saline-alkaline areas.

Abstract:With the promotion of green agricultural technology,the utilization of organic materials has been favored,but different types of organic materials have different effects on improving soil fertility. In order to explore the dynamic effect of organic materials application on the content of carbon and nitrogen in different forms and the enzyme activity in alluvial soil,a one-year culture test was conducted with treatments including add 10 g/kg of straw fungus residue (S),dendritic fungus residue (B),wheat straw (W),ryegrass straw (R),broad bean straw (BB),and Control (CK). The results showed that compared with CK,the application of organic materials significantly increased the carbon and nitrogen content in different forms and enzyme activity in soil. With the increase of the cultivation time,the organic matter and total nitrogen content showed increase trends with increases of 25.4% to 42.9% and 35% to 60%,respectively. The contents of easily oxidizable organic carbon and alkali-hydrolyzable nitrogen increased first and then decreased,and maximized at 2.80 and 43.26 mg/kg. Organic carbon,microbial biomass carbon and nitrogen,and enzyme activity showed a downward trend with the maximum values were 346 mg/kg,293 μg/g,and 23.08 μg/g. Organic material application could increase soil respiration rate by increasing soil enzyme activity. Through analysis of 7 hydrolytic enzymes at three sampling periods,the enzyme activity was: LAP > PHOS > NAG > BG > CB > AG > XYL,which indicating enzyme activity in the nitrogen cycle > enzyme activity in phosphorus cycle > enzyme activity in carbon cycle. Green manure straw mainly increased nitrogen cycle enzyme activity,and BB treatment had the highest enzyme activity. Mushroom residue mainly increased carbon cycle enzyme activity,the treatment activity of B was higher than that of S. Organic material application will affect soil enzyme activity and increase the content of different forms of carbon and nitrogen,but the increase varies depending on the types of organic material,and the response of the carbon and nitrogen components to the culture time is different. In general,wheat straw and broad bean straw showed the highest humification coefficient,and had the best effect on increasing the carbon and nitrogen content of different components.

Abstract:Based on the understanding of the spatial specificity of phytoremediation,aiming at the phenomena of eutrophication and black odor in water storage pond which is an important component of connecting the water system in Guanzhong area in recent years,three common floating-bed plants (canna,calamus,and Siberian iris) were selected to explore their purification effect for the raw water in the water storage pond by outdoor hydroponics test. The test lasted 35 days. The results showed that: (1) At the end of the experiment,the height and root length biomass of the three plants increased significantly,and the growth rate was as follows: canna > calamus > Siberian iris. (2) The average removal rates of TN in water bodies were 56.18%,52.17%,and 60.76%,respectively,which were higher than that of the control group (P<0.05). The average removal rates of TP in water bodies of canna and calamus were 55.42% and 58.32%,which were higher than the control group of 15.57% (P<0.05),but the Siberian iris group was not significantly different from the control group (P>0.05). In addition,canna and calamus could also adjust and improve pH and DO in the water. (3) The average removal rates of NH₃—N in water were 76.98%,65.71%,and 78.94%,respectively. The main removal pathways of NH₃—N in the canna and calamus were plant uptake and nitrification. The main removal route of NH₃—N in the Siberian iris group was mainly ammonia volatilization and nitrification,while the removal rate of NH₃—N in the control group was 60.55%,of which main removal reason was ammonia volatilization. The concentration of NO₃^-—N of plant group and control group increased with time,which was mainly related to the difference of water nitrification reaction and plant absorption efficiency in each experimental group. (4) Among the 3 floating-bed plants,calamus was suitable for the purification of the water of the point source pollution and non-point source pollution. The canna was only suitable for the purification of the water of non-point source,while the Siberian iris had poor purification ability and growth adaptation in both,which was not suitable for promotion as an aquatic floating-bed plant. The research results provide a reference for the selection of floating-bed plants for the restoration of polluted water bodies in water storage pond.

Abstract:In order to study the effect of different land use of saline-alkali soil on the soil salinization characteristics,the field investigation,sampling and indoor analysis were conducted. The morphological characteristics,soluble salt content,composition of salt ions,total alkalinity,pH,alkalinity and other indicators of soil profile were studied in six soil depths under five land use,namely,forest land,agricultural land,grassland,improved land and salt wasteland in Hetao plain. The results showed that there were significant differences in soil structure,color,root distribution,lime reaction and alkalinization of soil in different land use systems. The distribution of soluble salt and anion in soil profile was different due to different land use. Among them,grassland and forest land,were "olive",salt wasteland and improved land were "surface accumulation",and agricultural land was "bottom accumulation". The distribution characteristics of soil pH,alkalinity and total alkalinity in the profile were basically the same,showing an "S" pattern. The salinization degree and alkalinization degree of soil decreased with the different land use of saline-alkali soil,among which agricultural land was the most obvious. The total salinity,total pH alkalinity and ESP values of 0—20 cm soil decreased to 0.88 g/kg,7.83,0.17 cmol/kg and 12.54%,respectively,indicating that soda-saline and alkaline land was more conducive to soil desalination and dealkalization after agricultural use. Soil total salinity,Ca²⁺,Mg²⁺,SO₄^2-,total alkalinity and pH were the main factors of salinization in the studied area. These research results could provide technical reference for clarifying the salinization process and the improvement of salinized soil in Hetao plain.

Abstract:This research used the potted plant approach,BCR four steps work,flame atomic absorption method,and the method of dilution coated tablet to study the joint action of Rhodopseudanonas palustris and Bacillus subtilis,as well as the efficacy and safety,for remediation of cadmium pollution in farmland soil by Chinese cabbage in order to explore its effectiveness and to provide theoretical basis for application of the new type bio-bacterial manure. The results showed that either R. palustris or B. subtilis alone,or their combination could enhance the fixation of the metal in soil by increasing insoluble state cadmium and decreasing cadmium bioavailability. The combination of two bacteria significantly reduced cadmium bioavailability by 32.70%. All bacteria treatments showed significant influence on the number of soil microorganisms (P<0.05),and the amount of bacteria reached 10⁵ CFU/g. The treatments with various microorganisms all increased the plant height and fresh weight of cabbage,the content of chlorophyll a and b,and the ratio of chlorophyll a/b,meanwhile reduced the content of cadmium in the root and stem of cabbage with removal rate of 58.06%~71.37% and 73.66%~76.70%,respectively. The combination treatment group had the highest remediating effect with the biomass of Chinese cabbage increased by 18.13%~69.55%. The results demonstrated that the combination of R. spalustris and B. subtilis had a strong ability to remove cadmium from contaminated soil,could significantly promote the growth of Chinese cabbage,and showed the potential for remediation of heavy metal pollution in farmland soil.

Abstract:Based on soil salinization in vegetable fields of greenhouse,two bacteria (Bacillus mucilaginosus and B. megaterium that can dissolve the insoluble phosphate and potassium) were taken as study objects,microbial incubation and field experiments were conducted to investigate the effect of salt stress on the activity and the phosphate and potassium solubilization of two bacteria,and verify the effects of microbial inoculum application in lightly salinized greenhouse soil. The results showed that the maximum tolerated salt concentration was 10.5% NaCl and the optimum salt concentration of mixed bacteria was 0.5% NaCl,the available P and K concentrations dissolved from minerals were highest in growth medium with 0.5% NaCl and increased by 52.06% and 75.41%. The application of microbial inoculum in the vegetable field with high soil salinization significantly increased the levels of VC and soluble sugar in fruits of tomato,sweet melon,and water melon,and obtained greater yields with increment of 104.81%,23.72%,and 28.96% compared to the control. Moreover,the application of microbial inoculum significantly increased the concentrations of soil available phosphorus and potassium from the fields with tomato,sweet melon,and watermelon by 95.12%,22.83%,134.52%,and 92.71%,6.66%,117.46%,respectively,and significantly increased the number of soil bacteria (P<0.05). In conclusion,microbial inoculum with B. mucilaginosus and B. megaterium can colonize in slightly salinized soil,promote the release of te phosphorus and the potassium in the soil,increase vegetables yields,and improve the quality of vegetable fruits.

Abstract:To explore the physiological regulation of exogenous salicylic acid (SA) on Helianthus tuberosus under ClO₄^- stress,salt-tolerant Helianthus tuberosus L. from three different sites in Xuzhou,Weifang,and Nanjing were used as materials. The effects of exogenous SA on growth,root vitality,photosynthesis,and antioxidant capacity under 50 mmol/L NaClO₄ stress were studied by using foliar application and nutrient solution culture to cultivate plants. The results showed that ClO₄^- stress had different degrees of toxic effects on the growth and development of Helianthus tuberosus seedlings. Spraying exogenous SA could effectively reduce the stress damage to the plants,with similar change trend in Helianthus tuberosus L. from different sites. The biomass content,leaf area,plant height,and root length,as well as the chlorophyll content and fluorescence parameters of the leaves increased significantly,and achieved the maximum alleviation effect under SA spraying every day,while the root activity was better under the SA treatment every two days. At the same time,the content of H₂O₂ showed an increasing trend with the increases of SA spraying frequency. The increase in H₂O₂ content of each species was 47.69% when spraying SA every three days,while the increase rate was 50.93% for every two day,and 56.80% for every day. The activities of superoxide dismutase (SOD),peroxidase (POD) and catalase (CAT)were increased,and the content of both malondialdehyde (MDA) and free proline were significantly decreased (P<0.05),indicating that SA induced H₂O₂ to act as a signaling molecule to enhance the tolerance of plants in the ClO₄^- environment. The grey correlation analysis showed that the application of SA had the greatest influence on the chlorophyll fluorescence parameters and root activity of perchlorate stress. In summary,foliar application of 50 μmmol/L SA mainly affected the leaves and roots of Helianthus tuberosus. The ClO₄^- stress damage could be relieved by stimulating H₂O₂ to participate in the changes of antioxidant enzymes,and regulating the osmotic adjustment ability of plants to protect the photosynthesis and root activity. Spaying SA every day had the best effect. These findings would provide a basis for the further exploration of Helianthus tuberosus in ClO₄^- contaminated soil.