Abstract:[Objective]Amending soil with biochar and crop straw is an effective technique to improve soil quality and agricultural productivity.This paper investigates the long-term impact of continuous application of straw and biochar on soil aggregation and soil organic carbon(SOC)content in fluvo-aquic soil.[Method]A four-year(2019-2023)experiment was conducted in a winter wheat and summer maize rotation system in the western Shandong Plain.Biochar and maize straw were applied annually at the start of the winter wheat season.Straw was applied at rates of 3.80(S0.5),7.60(S1.0),11.40(S1.5),and 15.20 t/hm2(S2.0),while biochar was applied at rates of 1.14(B0.5),2.28(B1.0),3.42(B1.5),and 4.56 t/hm2(B2.0).The control treatment(CK)involved no soil amendment.After four years,we measured the changes in soil bulk density,aggregate stability,and SOC content in the 0-10 cm and 10-20 cm soil layers.[Result]Both straw and biochar applications reduced soil bulk density.The soil bulk density in the 0-10 cm soil layer under B2.0 treatment and in the 10-20 cm soil layer under B1.5 treatment decreased the most compared with the corresponding soil layers of CK,with significant reductions of 9.08%and 7.97%,respectively.Both of the two straw returning methods promoted the increase of soil aggregate to a certain extent,and the improvement effect was best for ˃5 mm soil aggregate,and worst for 1-2 mm soil aggregate.Compared with CK,the aggregate volume of ˃5 mm granular soil treated with B1.0 in 0-10 cm soil layer increased the most significantly by 107.35%,and that of ˃5 mm granular soil treated with S1.5 in 10-20 cm soil layer increased the most significantly by 106.63%.Except for SOC content in aggregates<0.25 mm in the 0-10 cm soil layer under S15.5 and aggregates of 1-2 mm in the 10-20 cm soil layer under B0.5,where SOC content decreased,biochar and straw application significantly increased SOC content in all other aggregate fractions and treatments.SOC content increased with the increase in biochar and straw application.[Conclusion]Annual applications of maize straw and biochar during the winter wheat season effectively improved soil quality by reducing bulk density,enhancing water-stable aggregates,and increasing SOC content in fluvo-aquic soil.For all treatments we compared,our results showed that applying 3.42-4.56 t/hm2 of biochar is most effective for improving soil quality in the studied region.

Abstract:[Objective]Soil conditioners are commonly used to improve quality and productivity of saline soils.This paper experimentally compares the effects of different soil conditioners on the physical and chemical properties of saline soils.[Method]The experiment was conducted in pots to simulate a rice-oilseed rape rotational cropping system.The soil was amended with calcium superphosphate at rates of 750 kg/hm2(G1)and 1 500 kg/hm2(G2);hydrolyzed poly(maleic anhydride)at rates of 900 kg/hm2(J1),1 200 kg/hm2(J2)and 1 500 kg/hm2(J3);and Bacillus megaterium at rates of 40 kg/hm2(W1),60 kg/hm2(W2),and 80 kg/hm2(W3).The control treatment(CK)was conventional fertilization without soil amendment.In each treatment,we measured physical soil properties and electrical conductivity of soil solution.[Result]Compared to CK,J2 increased soil total porosity,maximum water holding capacity,field water holding capacity,and capillary water holding capacity by 12.49%,13.60%,13.63%and 12.41%,respectively,while reducing electrical conductivity of the soil solution by 64.73%.W2 improved total soil porosity,maximum water holding capacity,field water holding capacity,and capillary water holding capacity by 8.59%,9.57%,9.01%,and 9.79%,respectively,while reducing electrical conductivity of the soil solution by 55.66%.W1 reduced soil bulk density by 4.20%,enhanced maximum water holding capacity,field water holding capacity,capillary water holding capacity and soil organic matter by 6.58%,9.02%,9.69%and 25.82%,respectively,while reducing electrical conductivity of soil solution by 8.97%.[Conclusion]Principal component analysis ranked the conditioners and their application rates in terms of their efficacy the following order:1 200 kg/hm2 of hydrolyzed poly(maleic anhydride)>60 kg/hm2 of Bacillus megaterium>40 kg/hm2 of Bacillus megaterium.These findings provide a guidance for practical application of soil amendment agents to improve properties and productivity of saline soils in the studied regions.

Abstract:[Objective]Water yield is a key parameter for assessing water productivity,with significant spatiotemporal variation.This study aims to analyze the spatiotemporal variation in water yield in the Gansu Section of the Yellow River Basin from 2000 to 2020.[Method]The InVEST model was employed to calculate water yield,while spatial pattern analysis,trend analysis,and hot-spot and cold-spot analysis were conducted to assess distribution patterns,temporal changes,and key areas of variation in water yield.[Result]Between 2000 and 2020,the average water yield in the Gansu Section of the Yellow River Basin increased from 295.09 mm to 442.12 mm.Water yield showed a strong correlation with elevation,with the highest water yield observed in Gannan Prefecture and the lowest in Baiyin and Qingyang.Land-use analysis revealed that liquid water bodies contributed the most to water yield,while contributions from snow and glaciers varied due to interannual climatic fluctuations.[Conclusion]From 2000 to 2020,the water yield in the Gansu Section of the Yellow River increased,with significant spatial variation.This variation was primarily influenced by elevation,climate conditions,and land-use types.These findings highlight the need for improved water resource management strategies in the region.

Abstract:[Objective]The Fuhe River Basin is an important food production region in Northwestern China.It is increasingly affected by droughts.This paper analyses the occurrence of droughts and their key determinants in this region.[Method]The analysis was based on modelling.We simulated the changes in monthly soil water content from 1962 to 2019 using the SWAT model.The resulting data were then used to calculate the standardized soil moisture index.The characteristics of agricultural droughts were analyzed using the theory of runs,and the key determinants of the droughts were analyzed using the geographical detector.[Result]① The coefficient of determination(R2)and the Nash efficiency coefficient(ENs)between the modelled and measured results in the calibration are both higher than 0.80;the coefficient of determination between the predicted soil moisture content and the measured soil moisture content is 0.52.② The duration of droughts in different regions in the basin varied from 3.60 to 4.31 months,and the drought intensity ranged from 4.91 to 5.61,both varying spatially,higher in the North and South and lower in the center.③ The influence of temperature,solar radiation,and wind speed on spatial variation in the droughts,characterized by the q-value,exceeds 0.30.Other environmental factors are nonlinearly interacted in their influence on the droughts.[Conclusion]The standardized soil moisture index can quantitatively characterize droughts in the Fuhe River Basin.Droughts in the basin vary spatially,with temperature,solar radiation and wind speed being the main contributing factors.

Abstract:[Objective]Soil anaerobicity is a common abiotic stress in fine-textured soils that adversely affects crop growth.Aerated irrigation,achieved by adding air bubbles to irrigation water,is a technique to mitigate soil anaerobicity.This study investigates the effect of regulated aerated irrigation on rice growth,physiological traits at different growth stages,as well as grain yield.[Method]The experiment was conducted in pots using the Zhongzao 39 rice variety as model plant.The controlled irrigation was implemented by keeping soil moisture at 80%-100%(T1)or 60%-80%(T3)of the field capacity during late-tillering stage;at 80%-100%at late-tillering and booting stage(T2);at 60%-80%during late-tillering stage and 80%-100%during booting stage(T4);at 80%-100%during middle and late tillering stages(T5),at 80%-100%from middle tillering stage to booting stage(T6),at 80%-100%during mid-tillering stage and 60%-80%during late tillering stage(T7),at 80%-100%during mid-tillering and booting stages and 60%-80%during later tillering stage.During non-controlled stages,all treatments kept a thin water layer at the depth of 0-30 cm on the soil surface.The control(CK)was conventional flooding irrigation by keeping a 0-30 cm of water layer on the soil surface.For each treatment,we measured abscisic acid(ABA),peroxidase activity(POD),pollen viability,OsFKF1 gene expression and grain yield.[Result]Compared with CK,the treatments significantly increased pollen viability,OsFKF1 expression at the heading and flowering stages,and grain yield.T3,T2 and T8 achieved the highest pollen viability(83.28%),OsFKF1 expression(2.96),and grain yield(83.908 g/plant),respectively.ABA activity in roots and leaves,and POD activity in leaves,at the mid-tillering stage differed significantly between treatments.Compared with CK,the treatments reduced ABA in roots at the mid-tillering stage by 16.73%-23.69%and POD activity in leaves at the late-tillering stage by 19.91%-66.70%;conversely,they increased ABA in roots at the booting stage by 1.37%-63.52%.At the mid-tillering stage,T1—T4 reduced POD activity in roots by 70.36%-71.55%,whereas T5—T8 increased POD activity in roots by 2.53%-7.00%.Multiple linear regression analysis showed that the treatments increased ABA in roots at the late-tillering stage,reduced ABA in leaves at the late-tillering and booting stages,and decreased POD activity in leaves at the mid-tillering and late-tillering stages.These enhanced pollen viability and OsFKF1 gene expression at the heading and flowering stages,thereby increasing grain yield.[Conclusion]Among all treatments,T3 was the most effective in regulating ABA and POD,enhancing pollen viability,and improving rice grain yield,which reached 82.18 g/plant.

Abstract:[Background]Soil salinization is a widespread abiotic stress that significantly impacts agricultural productivity and water resource management in the Yinbei region of Ningxia Province.This study explores the inter-annual dynamics of soil salinity and groundwater depth in areas within this region that use surface irrigation and subsurface drainage.[Method]Field investigations were conducted in Huinong,a representative area in northern Yinbei characterized by surface irrigation and subsurface drainage systems.Spatiotemporal variation of soil salinity and groundwater depth were analyzed using measured data with the help of correlation analysis and the inverse distance weighting(IDW)interpolation method.[Result]Temporally,areas with high soil salinity were accounting ting for 23.57％of the study region in April.In contrast,areas with soil salinity greater than 2 g/kg decreased by 52.99％in July and 26.3％in October,compared to April.Soil salinity decreased gradually with increasing groundwater depth,and the relationship between them was well fitted by a proposed model(R2＞0.82).[Conclusion]Soil salinity in the region peaks in spring and declines by summer,showing spatial variability influenced primarily by topography and irrigation practices.Salinity in the 40-100 cm soil layer was more responsive to groundwater depth than in the 0-40 cm layer.Maintaining a groundwater depth between 1.8 and 2.2 m can facilitate crop growth and reduce salinization risk.

Abstract:[Objective]Drought is a significant abiotic stress affecting agricultural production in many regions of China.This study investigates the spatiotemporal variations in drought during the growing seasons of summer maize in the Huaibei Plain.[Method]The analysis was based on the drought severity index(DSI)from 2010 to 2019 calculated using metrological data measured from weather stations across the region.We focused on the top 0-10 cm soil layer and the root zone from the soil surface to the depth of 50 cm.The M-K test and the Kriging spatial interpolation were used to analyze the spatiotemporal variation in droughts over the region at different time scales.[Result]① Since 2016,the severity and frequency of droughts have both significantly increased in the areas of Dangshan,Mengcheng,and Qiaocheng,while decreased in the area of Fuyang.In Suzhou,droughts mainly occurred in 2010-2012 and 2019.Compared to seasonal scale,some drought events exhibited greater severity and higher frequency at the ten-day scale with unpredictable onset.②The highest average annual drought index and frequency both occurred during the sowing-emergence stage,reaching moderate level or above,with the frequencies exceeding 40% .Severe droughts or worse at both timescales occurred in northern Dangshan and central Mengcheng and Suzhou.The frequency of the 0-10 cm soil-layer droughts was higher in the southwest,while the frequency of 0-50 cm soil-layer droughts was higher in the east and north than in other areas.③ At the ten-day scale,the periods with the highest drought severity in each growing season mostly started in the early stage of sowing-emergence,emergence-jointing,and the mid-stage of jointing-tasseling.Severe droughts occurred primarily in August and September.[Conclusion]Since 2016,there has been a significant increase in drought severity and frequency for summer maize in the Huaibei Plain,particularly during the sowing seedling stage.Severe droughts were observed at uncertain ten-day scales,with increased drought frequency.

Abstract:[Objective]The increase in atmospheric CO2 and the associated global warming is expected to affect plant growth and development.This paper investigates the spatiotemporal variation in vegetation phenological traits and peak NDVI of plants in Hetao Irrigation District in Inner Mongolia.[Method]The analysis was based on MOD13Q1 data from 2001 to 2021.The impact of climatic factors on spatiotemporal variation in the start of season SOS,the end of season(EOS),the length of season(LOS),the peak of season(POS),and the normalized difference vegetation index(NDVI)of the vegetations in the region was analyzed using the two-logistic and four-parameter model.[Result]The SOS started from the end of May to the middle of June,and ended from the middle of September to the beginning of October.The annual peak LOS and POS ranged from 95 to 116 days,and from 200 to 220 days,respectively.The annual peak NDVI ranged from 0.5-0.7.Climate change delayed the onset of SOS,reduced LOS,and elevated peak NDVI.Additionally,the delayed SOS contributed to the decrease in LOS.The changes in EOS and POS with climate were consistent.SOS,EOS and POS were negatively correlated to temperature and positively correlated to precipitation.The peak NDVI was positively correlated to temperature and precipitation.[Conclusion]The vegetation phenology and peak NDVI in the Hetao Irrigation District were spatially heterogeneous,and the impact of climatic factors on them also varied.

Abstract:[Objective]Acrylate polymer blended with poly(vinyl chloride)resin(ABR)is a composite material to make pipes.This paper investigates the pipe network manufactured by it for irrigation and drainage.[Method]The study was based on field experiments and CFD simulations.Based on performance of the network under different configurations,we optimized the system and applied it to dry-land chili pepper grown in Shandong plains in Northern China.[Result]①Compared with single-ring and tree-like pipe network configurations,the double-ring and equidistant pipe network configuration in the ABR system reduced the coefficient of variation of water discharge for each irrigation-drainage pile by 1.327 to 0.766,thereby enhancing water supply balance.②The suitable area for a single set of pipe network systems was 1.5 hm2,and the distance between the irrigation-drainage piles was 50 m.Under these conditions,water flow velocity at the outlet of each pile varied from 0.60 to 0.24 m/s,and each irrigation event can be completed in 12 h.③The drainage capacity of each pile was 28.8 m3/h,sufficient to alleviate waterlogging during heavy rainfalls.[Conclusion]The proposed irrigation-drainage system significantly improved irrigation and flooding-control for the chili pepper grown in the dryland in the study area.It has a wide implication and application for crop productions in other regions.

Abstract:[Objective]Evaluating evapotranspiration and soil salinization is critical for soil and water management but challenging on large scales.This paper investigates the feasibility of using remote sensing technologies and meteorological data to estimate evapotranspiration and soil salinization in irrigated areas.[Method]The study was conducted in the Manasi River Basin in Northeastern China.It was based on the Surface Energy Balance System(SEBS)model,using the Landsat-8 remote sensing data and field sampling to estimate spatial distribution of both evapotranspiration and soil salinity in the studied area.[Result]① The normalized vegetation index(R2=0.644 8),surface specific emissivity(R2=0.637 7),and surface temperature(R2=0.558 3)all showed a strong correlation with soil salinity,while surface albedo(R2=0.198 6)had a weaker correlation with soil salinity.② Daily evapotranspiration(ET)in the Manasi River Basin ranged from 0.024 to 5.403 mm,with an average of 3.866 mm.ET decreased from the Southern irrigation area to the Northern Gobi region.③ ET values less than 3.60 mm/d were associated with non-saline and moderate saline soils.For areas with ET between 3.60 mm/d and 4.05 mm/d,moderate soil salinity dominated.For areas with ET exceeding 4.05 mm/d,the proportion of severe soil salinity increased significantly.[Conclusion]Using remotely sensed satellite imagery,the SEBS model provides an accurate,high-resolution estimate of evapotranspiration in terrestrial systems.The evapotranspiration was positively correlated with soil salinity in the Manasi River Basin.These results can help improve land and water management in the region.

Abstract:[Objective]Agriculture is the main water consumer in many countries and regions,and improving agricultural water use efficiency is critical to sustainable development in these regions.A prerequisite for this is to understand the potential for water saving in the agricultural sector.This paper presents a method to evaluate agricultural water-saving potential in arid regions.[Method]The method considered the influence of desertification,soil erosion,and other environmental factors on water conservation.A total of 30 key factors,including agricultural water consumption,irrigated land area,irrigation water use efficiency,grain-to-economy ratio,and soil and water conservation rate,were considered in the evaluation.Using the Vensim PLE software,a system dynamic flow diagram model was developed to calculate agricultural water-saving potential.The model was applied to Inner Mongolia(excluding Dongsimeng City)to evaluate its agricultural water-saving potential at regional scales,in both the short term(up to 2035)and the long term(up to 2050).[Result]① Agricultural water-saving potential in Inner Mongolia was estimated to be 2.518 billion m3 in the short term(up to 2035)and 2.958 billion m3 in the long term(up to 2050).Among all areas in the province,Bayannur had the highest water-saving potential,while Wuhai had the least.② Engineering water-saving projects contributed the most to the water-saving potential(approximately 52.83%),while technical water-saving measures contributed the least(approximately 16.91%).The contribution of engineering water-saving projects to water savings is expected to increase over time.[Conclusion]Our results demonstrate that the system dynamic model can be used to estimate agricultural water-saving potential.The results obtained using this model are reliable and provide valuable technical support for formulating agricultural water-saving policies in arid regions.

Abstract:[Objective]Irrigating vegetables with biogas slurry is an environmentally friendly approach for recycling organic waste in urban fringe areas.This study investigates the effects of combining biogas slurry with chemical fertilizers on the yield of spring onion(Allium fistulosum L.),soil nutrient content,and the soil microbial community.[Method]The experiment was conducted from May to October 2022 using the Zhangqiu variety of spring onion.Five topdressing treatments were applied:no fertilization(NF),chemical fertilization(CF),biogas slurry alone(BS),biogas slurry combined with fertilizer 1(BSF1),and biogas slurry combined with fertilizer 2(BSF2).The effects of these treatments on onion yield,nutrient uptake and utilization,soil fertility,and soil bacterial community composition were measured and analyzed.[Result]Compared to NF,CF,BS,BSF1 and BSF2 increased onion yield by 37.48％,63.33％,92.53％,and 59.78％,respectively.Compared to CF,BS,BSF1 and BSF2 improved fertilizer utilization efficiency(FUE)by 50.63％to 71.06％;total organic carbon(TOC)by 17.90％to 28.51％;dissolved organic carbon(DOC)by 39.80％to 47.11％;and total nitrogen(TN)by 21.28％to 81.91％.BSF1 had the highest nitrogen use efficiency(NUE)and FUE,at 59.34％and 31.60％,respectively.Compared to CF,BS and BSF1 significantly increased the relative abundance of Chloroflexi while reducing that of Acidobacteria.CF notably reduced the α-diversity index of the soil bacterial community.[Conclusion]Compared to chemical fertilization alone,application of biogas slurry in combination with reduced chemical fertilization(BSF1)enhanced onion yield,nutrient use efficiency,soil carbon and nitrogen content,and improved the soil microbial community.Among all treatments,BSF1 proved most effective in enhancing both productivity and fertilizer use efficiency of the spring onion.

Abstract:[Objective]Environmental changes and human activities have significantly affected the ecological functions of the Poyang Lake Basin.Herein,we analyze the spatiotemporal variation in the resilience of water resources,economy and ecosystems in the basin,as well as the factors influencing them.[Method]The analysis covers 11 metropolitan regions within the basin.An evaluation index system based on the Pressure-State-Response(PSR)framework was developed,and the index weights were determined using the entropy weight method.Spatiotemporal variations in resilience across the pressure,state,and response dimensions were examined using a comprehensive evaluation approach.The geographic detector method was employed to identify the primary factors and their interactions that influence the economic and ecological resilience of water resources.[Result]① From 2010 to 2020,the pressure resilience,response resilience,and overall resilience indices had steadily increased,whereas the state resilience showed minimal change.Most areas in the basin continued to experience low resilience levels.② During this period,resilience levels among the 11 regions displayed an alternating high-low pattern.Spatially,pressure and overall resilience showed limited regional variation and remained generally high,while state and response resilience increased from the center toward the northern and southern parts of the basin.The overall resilience level across the basin requires improvement.③ Economic factors were found to be the dominant drivers of resilience in the water-economy-ecosystem system.Interactions between per capita GDP,industrial structure,and ecological background were found to have significant impact on system resilience.[Conclusion]Strengthening overall basin planning,improving water resources management and pollution control,and transforming agricultural practices can enhance economic and ecological resilience of water resources in the basin.These measures are crucial for sustainable use of water resource,economic development and ecological protection in the basin.

Abstract:[Objective]Maize-soybean intercropping is a common cultivation technique in Northwestern China.However,one challenge with this system is the uneven distribution of interspecific light energy and the inefficient use of light and irrigation water.This study proposes a strategy to enhance crop canopy cover and photosynthesis by controlling irrigation during the non-critical reproductive period of maize.The objective is to reduce the shading effect of maize on soybean while improving yield and light energy utilization efficiency.[Method]A field experiment was conducted with four irrigation treatments:① sufficient irrigation for both maize and soybean(IW1),②sufficient irrigation for maize and deficient irrigation(50%)for soybean(IW2),③ deficit irrigation for maize(50%)and sufficient irrigation for soybean(IW3),and ④ deficit irrigation(50%)for both maize and soybean(IW4).Soybean was intercropped with two maize varieties:Xianyu 335(C1)and Longdan(C2).A monocropping system served as the control,with two irrigation treatments:sufficient irrigation(MW1)and deficit irrigation(MW4).The experiment measured morphological indices,net photosynthetic rate(Pn),canopy changes,light energy interception,competition ratio(CR),land equivalent ratio(LER),and irrigation water use efficiency(iWUE)for both crops under each treatment.[Result]① Under the same irrigation treatment,soybean intercropped with C1 showed significantly higher Pn(26.90%),leaf area index(LAI)(5.38%),and aboveground biomass(5.42%)compared to intercropping with C2.Additionally,it reduced the intercepted photosynthetically active radiation(IPAR)of soybean by 6.25%while significantly improving the total radiation use efficiency(RUE)of the intercropping system.② Changes in irrigation had significant effects on Pn,plant height,LAI,and aboveground biomass for both crops.In particular,IW3 reduced irrigation requirements by 16.79%compared to IW2,significantly increased Pn,LAI,and biomass of soybean,and decreased IPAR by 10.43%.Intercropping improved total RUE by 2.42%.③ Under the same irrigation treatment,soybean intercropped with C1 had higher yield,iWUE,and CR compared to intercropping with C2.The total LER of C1 also increased by 2.38%.④ Compared to IW2,IW3 increased soybean yield by 19.95%,total iWUE by 15.17%,and total LER by 8.12%.[Conclusion]Among all treatments,IW3 combined with soybean intercropped with the maize variety Xianyu 335 significantly enhanced soybean growth and improved radiation use efficiency for both crops.This strategy offers a promising approach to optimizing resource use and increasing the productivity of the maize-soybean intercropping system.

Abstract:[Objective]Following China's mandate for zero growth in fertilizer use in agricultural production,improving fertilizer and irrigation water efficiency has become a key priority for sustainable agriculture.Astragalus mongholicus is an important medicinal herb grown in Northwestern China.This study investigates how reducing fertilizer application combined with fertigation(integrated fertilization and irrigation)influences the growth and yield of Astragalus mongholicus.[Method]The experiment was conducted on sandy soil in Horqin,Inner Mongolia,focusing on Astragalus mongholicus seedlings.It included five treatments:conventional fertilization combined with spraying irrigation(CS),conventional fertigation(CW),conventional fertigation with a 30%nitrogen reduction(TW),and conventional fertigation with a 50%nitrogen reduction(FW).During the experiment,plant growth parameters and fertilizer requirements were measured for each treatment.[Result]① Fertigation significantly improved plant growth traits,particularly root length and fresh root mass.② Between 83 and 118 days after seedling emergence,the plant exhibited the fastest dry matter accumulation and the highest demand for phosphorus and potassium absorption.③ Compared to conventional fertilization combined with micro-spraying irrigation,reducing nitrogen application by 30%combined with fertigation increased nitrogen and phosphorus use efficiency,crop yield by 15.93%,and water use efficiency by 33.33%,leading to a net income increase of 32 648.26 yuan/hm2.[Conclusion]Our results provide valuable insights for optimizing nitrogen,phosphorus,and water application in the intensive and sustainable cultivation of Astragalus mongholicus in the studied region.

Abstract:[Objective]Extreme weather events like drought are expected to become more frequent in the context of climate change.Studying and understanding its spatiotemporal variation and the underlying drivers is critical to mitigating its detrimental impact.This paper analyzes drought trends and their influencing factors in a representative region in Southwest China.[Method]The study region is the Jinsha-Yuan River dry-hot valley in Yunnan Province.Using land surface temperature and the normalized difference vegetation index,we constructed a temperature vegetation dryness Index(TVDI).We then integrated natural and anthropogenic factors,including annual mean temperature,precipitation,evapotranspiration,and nighttime light intensity,and applied piecewise linear regression,the Mann-Kendall test,Theil-Sen slope estimation,GeoDetector,and correlation analysis to investigate the spatiotemporal changes in TVDI from 2001 to 2020 in the region.[Result]Temporally,TVDI exhibited a generally decreasing trend though with fluctuations.However,a significant shift occurred in 2018,after which drought became worse.Spatially,48.1%of the area experienced moderate to severe drought,with Yuanmou,Huaping,Binchuan,and Yongren counties in the Jinsha River Basin and areas along the Yuan River identified as drought hotspots,which require priority monitoring and control.In contrast,there was less drought in Northeast and Northwest of the region.Temperature,altitude and evapotranspiration were the natural factors that affected drought variation the most,while human influence was relatively minor compared to natural factors.[Conclusion]From 2001 to 2020,drought conditions across the study area generally improved,though with notable spatial heterogeneity.Natural environmental variables played a key role in shaping drought dynamics,underscoring their importance in regional drought risk assessment and management.

Abstract:[Objective]Irrigation water use efficiency is an important parameter in irrigation design.It depends on various factors.In this paper,we compared irrigation water use efficiency calculated using the whole-process method and the head-tail method,from which we further studied the factors that influence water loss in irrigation districts.[Method]The study area was Zhongjiang County in Sichuan province.We divided the county into four regions(represented by TW,TH,ON and FO),each region having its typical canal systems and field conditions.The whole-process method calculated the irrigation water use efficiency in each region using a combination of hydrodynamic method,empirical formula and irrigation experiments.The head-tail method calculated the total irrigation amount in each region first by measuring the water flowing into and out of the region at the heads and tails,respectively,as well as other water sources flowing into and out of the region;these,along with the irrigation water consumed by crops,were used to calculate the irrigation water use efficiency.[Result]The canal water use efficiency in the largest TW regions was 0.596 and the smallest TH regions was 0.564,with a weight-average of 0.580.The water use coefficient in ON and TW regions in the north of the county was 0.90,thanks to their good hydraulic engineering projects.Affected by their topography,the water use coefficient in the TH and FO regions was 0.85.When the required irrigation guarantee was 75％,the irrigation water use efficiency calculated by the whole-process method was 0.503,compared to 0.492 calculated by the head-tail method.[Conclusion]The irrigation water use efficiency calculated by the two methods is comparable and their results are reasonable.The proposed method and the results can help to improve irrigation water use efficiency in regions where the irrigation water use efficiency is currently lower than the national average.

Abstract:[Objective]HYDRUS is a software widely used to simulate soil water movement,but it requires evapotranspiration which is difficult to obtain at large scales.In this paper,we investigated the feasibility of combining it with remote sensing to simulate spatiotemporal soil water dynamics at large scales.[Method]The experiment was conducted in a summer maize field in Daxing District,Beijing.The evapotranspiration estimated from the MODIS data and the surface energy balance system(SEBS)model was decoupled into soil-surface evaporation and plant transpiration,which were combined with the HYDRUS-1D to simulate spatiotemporal water dynamics in soil profile.Field-scale soil water dynamics was modelled by embedding the HYDRUS-RS model with the geographic information system(GIS)platform.The models were then applied to simulate spatiotemporal changes in soil water in the summer maize field during its growing season in 2018.[Result]The SEBS model was the best in modelling Rn,with the coefficient of determination(R2),bias and root mean square error(RMSE)being 0.81,11 W/m2,and 54.8 W/m2,respectively.In the experimental area,the estimated daily ET during the growing season of the maize in 2018 varied between 3 and 6 mm/d.This differed slightly from that directly estimated from the soil moistures measured from pre-defined sampling points,but their temporal variation trends were the same.During growing season of the summer maize,soil moisture simulated by the proposed HYDRUS-RS model for the 40-60 cm soil layer was accurate,with the bias,RMSE,and R2 being 0.2％,2.1％and 0.80,respectively.[Conclusion]Combining remote sensing with HYDRUS-1D provides a robust and accurate method for simulating large-scale soil water dynamics in agricultural lands.For the summer maize crop we studied,this integrated approach effectively predicts the changes in soil moisture,particularly in the 40-60 cm root zone.

Abstract:[Objective]The presence of undigested antibiotics used in livestock farming poses significant environmental concerns,as their disposal into water and soil can lead to contamination of the food chain.This paper presents the analysis of the distribution and concentration of these antibiotics in both soil and groundwater.[Method]Soil and groundwater samples were collected from an intensive livestock farming area in H county.Antibiotics and hormones in these samples were analysed using the high-performance liquid chromatography-triple quadrupole mass spectrometry.[Result]① On average,there was more sulfonamide(SAs)in soil than in groundwater.All but megestrone acetate hormones were found in soil and groundwater,although there were more in soil than in groundwater.② Sulfamethiazole,sulfonamide intermethacil,sulfonamide and sulfoamine were found in soil.In the groundwater,the concentrations of sulfonamide intermethacil and sulfamquinoxine were higher than the concentration of other antibiotics.③ The concentration of hormone KTY04 was higher in the 0-20 cm soil layer than in the 60-80 cm layer.In the studied area,adrenocorticoid,testosterone,and notestosterone were the dominant hormones,with their mass concentration reaching 325 ng/L.[Conclusion]Our study found higher mass concentrations of sulfonamides in soil than in groundwater,except estrogen whose concentration was high in groundwater and moderate in soil.The presence of antibiotics and hormones from livestock farming could lead to increased contamination of both soil and groundwater,particularly sulfonamides and estrogens.Continuous monitoring is needed to assess their potential impacts on ecosystems.

Abstract:[Objective]This paper is to propose a method to optimize ecological space zoning and develop scientific management strategies for watersheds.The focus is on clarifying the synergies and trade-offs among mountains,waters,forests,farmlands,lakes,and grasslands.[Method]The study takes the Hongfeng Lake watershed as a case study.It is a typical watershed consisting of mountains,water,forests,fields,lakes and grasses.Quantitative and qualitative methods were used to calculates synergies and trade-offs between these sub-ecosystems at both basin scale and local scale.The ecological zoning in the watershed was analyzed by considering the synergistic relationships between mountains,waters,forests,farmlands,lakes and grasslands.[Result]The study revealed significant spatial variation in ecological zones within the studied areas.It identified contrasting spatial relationships in the distribution of synergies and trade-offs,particularly between water and other subsystems,as defined by the water intersection line.Key findings include differentiated ecological protection roles of forests and grasslands,high pollution risks facing lakes,and the reliance on rainfall for agriculture outside regions where lakes effectively manage water storage.The watershed was classified into nine ecological control zones,including urban water source protection zones and ecological agricultural zones along the lake and its tributaries.Additionally,mountain areas were designated as ecological industrial development and conservation zones,water source conservation zones,and geo-hazard risk zones.[Conclusion]By analyzing the coordination and trade-offs among various ecological components,this study ensures the maximization of ecological diversity within each zoning type.The findings highlight the need for tailored management strategies across different zones to address their unique ecological needs and challenges.