Evaluation of water schemes for peanut,using CSM-CROPGRO-Peanut model

Drought stress is an important factor limiting the yield potential of peanut. In order to determine the effect of different irrigation scenarios on peanut production, field experiments were conducted in 2011 and 2012 growing seasons using factorial design with three replicates. On the other hand, the crop simulation models can be useful to predict crop yields and to investigate the impact of drought stress on plant growth and development. In this study, the Cropping System Model–Crop Growth (CSM-CROPGRO)-Peanut model was employed for the simulation of seed yield, pod yield, biomass, soil water balance components and water productivity for peanut in Astaneh-Ashrafiyeh, Iran. Results showed that the model was able to reasonably simulate seed yield, pod yield and final biomass for different irrigation scenarios (RMSEn < 20%, R² > 0.8 and d > 0.8). According to the results, irrigation depth and interval were important factors affecting yield and biomass. In general, model error increased as the amount of water applied decreased. The least amount of water applied (40 mm) resulted in yield reductions by 76%, 70% and 67% of the greatest amount of water applied (480 mm) for seed yield, pod yield and final biomass, respectively. For each irrigation interval, larger irrigation depth led to lower water productivity (WP) of irrigation (WP_I), but higher WP based on evapotranspiration (WP_ET) and transpiration (WP_T).The average amounts of WP_I, WP_ET, WP_T based on seed yield were 1.2, 0.63 and 1.01 kg m^?3, respectively.     

Evaluation of Water–Nitrogen Schemes for Rice in Iran,Using ORYZA2000 Model

The model ORYZA2000 simulates the growth and development of rice under conditions of potential production and water and nitrogen (N) limitations. Crop simulation models could provide an alternative, less time-consuming, and inexpensive means of determining the optimum crop N and irrigation requirements under varied irrigation and nitrogen conditions. Water productivity (WP) is a concept of partial productivity and denotes the amount or value of product over volume or value of water used. For the evaluated ORYZA2000 model in Iran, a study was carried out in a randomized complete block design between 2005 and 2007, with three replications at the Rice Research Institute of Iran, Rasht. Irrigation management (three regimes) was the main plot and N application (four levels) was the subplot. In this study, simulation modeling was used to quantify water productivity and water balance components of water and nitrogen interactions in rice. Evaluation simulated and measured total aboveground biomass and yield, by adjusted coefficient of correlation, T test of means, and absolute and normalized root mean square errors (RMSE). Results showed that with normalized root mean square errors (RMSE_n) of 5–28%, ORYZA2000 satisfactorily simulated crop biomass and yield that strongly varied among irrigation and nitrogen fertilizer conditions. Yield was simulated with an RMSE of 237–443 kg ha^?1 and a normalized RMSE of 5–11%. Results showed that the significant (28–56%) share of evaporation into evapotranspiration, using the actual yield (measured) and simulated water balance (ORYZA2000), the calculated average WP_ET was significantly lower than the average WP_T: 37%. The average WP_I, WP_I+R, WP_ET, WP_T, and WP_ETQ were 1.4, 1.07, 1.07, 1.57, and 0.82 kg m^?3. Results also showed that irrigation with 8-day intervals and 60 kg N ha^?1, nitrogen level was the optimum irrigation regime and nitrogen level.     

农田耗水构成、规律及影响因素分析

农业用水占总用水量的70%左右, 对农田耗水规律和过程的研究对发展区域节水农业有着非常重要的作用。本文通过回顾中国科学院栾城农业生态系统试验站建站以来在农田水分循环和节水方面的研究进展,对长期定位试验下不同灌溉水量的耗水规律、农田耗水过程及影响农田耗水的因素进行了分析。通过利用水量平衡法和大型蒸渗仪测定等方法确定蒸散量, 用小型蒸发器测定土壤蒸发。长期定位试验的结果表明: 在该区域冬小麦-夏玉米一年两作的种植方式下, 这两种作物耗水量相似, 随着灌溉量的增加, 农田耗水有增加的趋势; 冬小麦的农田耗水量在283~493 mm 之间, 灌溉水量较小处理的变异系数较大。利用大型称重式蒸渗仪和自制的微型蒸发器(MLS)测定的冬小麦和夏玉米季的棵间蒸发均占蒸散量的1/3。因此, 在此基础上可以利用秸秆覆盖减少土壤蒸发且效果非常明显, 20 年的试验表明秸秆覆盖每年可以减少土壤蒸发40~50 mm, 冬小麦秸秆覆盖夏玉米田可以抑制棵间蒸发的58.0%, 夏玉米秸秆覆盖冬小麦田可以抑制蒸发40.4%。长期耕作的定位试验表明: 不同耕作方式下的土壤蒸发也存在明显的差异, 免耕加秸秆覆盖处理的蒸发最小, 而深耕的最大。同时, 不同灌溉制度、种植方式和冠层结构均会对农田耗水产生影响。这些研究结果为以后的节水理论和技术发展提供了依据。     

Combined Effect of Poultry Manure and Soil Mulching on Soil Properties,Physiological Responses,Yields and Water-use Efficiencies of Sorghum Plants under Water Stress

ABSTRACT

The present investigation was planned to determine the effect of deficit irrigation, mulching and poultry manure application on sorghum grain, forage yield and water-use efficiencies. Two field experiments were conducted during 2016 and 2017 growing seasons at Demo farm, Fayoum, Egypt. Eighteen treatments comprising of two rates of rice straw as soil mulching (SM; zero and 10 ton per hectare), three irrigation treatments (I_100% = 100%, I_85% = 85% and I_70% = 70% of crop evapotranspiration (ETc) and three poultry manure (PM) levels (0, 24 and 36 ton per hectare) were studied under controlled surface irrigation system. Sorghum growth attributes (plant height, stem diameter, leave area), grain and forage yield, water-use efficiencies (G-WUE and F-WUE) were significantly (p < .05) affected by irrigation quantity and both soil mulch and poultry manure application. Poultry manure resulted in a significant decrease in soil bulk density, electrical conductivity (ECe), soil pH, hydraulic conductivity and total porosity, useful pores, and water holding pores were increased. The results showed that underwater scarcity, application of (I₈₅ × PM₃₆× SM₁₀) treatment was found to be favorable to save 15% of the applied irrigation water as compared to I₁₀₀, at the time produced the same sorghum yields.     

Nutrients uptake and water use efficiency of drip irrigated maize under deficit irrigation

Little is known about nutrient uptake during different growth stages of drip irrigated maize under deficit irrigation. A 2-year field study in the semi-arid region of Upper Egypt was carried out in a randomized complete block design with five replications during the summer of 2016 and 2017. Maize plants were irrigated with 100, 80, or 60% of water requirements. Maize growth was negatively affected by the lower water supply. Total uptake of nitrogen (N), phosphorus (P), and potassium (K) by maize irrigated with I₁₀₀ increased by 21, 25, and 21% compared to that irrigated with I₆₀. I₈₀ reduced the grain and straw yield by 8 and 17% compared to I₁₀₀. Under deficit irrigation water was used efficiently more than full water supply. NPK requirements of drip irrigated maize under deficit irrigation are less than those irrigated by full water supply thus help to sustain the environmental ecosystem and increased the economic returns.     

免耕旧膜再利用对玉米产量及灌溉水生产力的影响

在河西走廊中段边缘绿洲安排田间试验,明确保护性耕作地膜再利用栽培对玉米产量及灌溉水生产力的影响,探讨降低农田残膜污染、节本增效和可持续土地利用的耕作栽培管理方式。试验涉及3种不同质地与肥力水平的土壤,设3个处理:(1)传统耕作与冬灌、覆新膜栽培(NM);(2)免耕少冬灌、旧膜直播(RM);(3)免耕少冬灌、旧膜直播行间秸秆覆盖(RMS)。结果表明,在玉米播种后至拔节期前,日平均土壤温度2个免耕旧膜直播处理较传统覆新膜处理仅低0.6~1.0℃(5 cm土层)和0.5~0.8℃(15 cm土层),表明旧膜直播仍具地膜覆盖提高地温的效应。玉米产量免耕旧膜直播较覆新膜降低4.4%~10.6%,但节省了耕作和地膜投入,收益增加。免耕旧膜直播结合秸秆覆盖栽培方式玉米产量与新覆膜栽培持平,净收入提高12.5%~17.1%。免耕旧膜直播栽培减少了冬灌量,灌溉水生产力提高。土壤质地与肥力水平对作物吸氮量、灌溉水生产力影响显著。在水资源紧缺的干旱区绿洲,适时进行保护性耕作地膜再利用栽培技术是节本增效、土地可持续利用的一种选择。     

An evaluation and comparison of drip and conventional furrow irrigation methods on maize

A field study was conducted over two years on maize at Islam Abad Research Station at 34°7′42′′N and 46°27′23′′E and elevation of 1348 m a.s.l in Kermanshah Province, western Iran in order to compare the effects of different irrigation methods and treatments on irrigation water use efficiency, crop yield, yield response factor, pan and seasonal crop coefficients, and other maize parameters. The experiment was a complete randomized block design with three replicates. During the study, irrigation water was applied at 40, 60, 80 and 100% of the maize seasonal water requirement for different surface drip tape (SDT) treatments, and 100% only for conventional furrow irrigation treatments with and without soil and water monitoring. The results showed that by using the above-mentioned different drip tape and surface treatments with soil and water monitoring, maize seasonal irrigation water use savings of 81, 71, 61, 52 and 36% were achieved compared with local conventional furrow irrigation without any soil, water and root monitoring, respectively. The yield response factor (K _y), seasonal crop (K _c) and pan coefficient (K _p) for maize were 0.80, 0.76 and 0.97, respectively.     

农业技术和气候变化对农作物产量和蒸散量的影响

随着农业生产条件的改善、品种改进和有利的气象条件的变化, 世界各地的作物产量得到大幅度提高, 但作物的蒸散量却未出现大幅度提高。本文以石家庄气象站1955~2007 年的气象资料为基础, 分析了河北省冬小麦和夏玉米生长期间主要气象因素变化, 结合中国科学院栾城农业生态系统试验站长期定位灌溉试验的研究结果, 分析了农业生产条件和气象因子变化对冬小麦和夏玉米产量及耗水量的影响。结果表明,1955~2007 年冬小麦和夏玉米生长季的气象因子发生了变化, 日照时数、相对湿度、风速、气温日较差显著降低, 最低气温、平均气温和积温显著升高, 气象因子的变化对作物总蒸散量未产生明显影响, 但由于降水减少,作物生长期间的灌溉需水量呈增加趋势。长期灌溉试验结果表明, 随着农业生产条件的变化和品种的改良, 冬小麦和夏玉米的产量不断增加, 而耗水量的增加幅度小于产量增加幅度, 夏玉米的耗水量呈稳定状态。节水技术的推广和应用对维持耗水量稳定起着非常关键的作用。     

华北高产粮区基于种植制度调整和水氮优化的节水效应

冬小麦/夏玉米一年两熟是华北平原粮食作物主要的种植方式。冬小麦生育期降水少,春季灌溉是保证其高产的必要措施。基于上述问题,在华北平原高产粮区设置田间试验,研究了调整种植制度和水氮优化等措施下的节水效应。结果表明,将一年两熟的冬小麦套种夏玉米调整为冬小麦直播夏玉米,并结合水氮优化等措施,能降低作物耗水15%,提高灌溉水利用效率52%～54%,而产量并没有下降;而将一年两熟调整为两年三熟和一年一熟,尽管能降低作物耗水24%～31%,且能提高灌溉水利用效率58%～172%,但产量却下降16%～27%。综上所述,该区将现行的一年两熟制中的套种调整为直播,并加以水氮优化等措施,是目前较为适宜的种植方式。考虑到该区水资源严重短缺的现实,两年三熟制可能是未来的种植趋势,但需要挖掘其产量潜力。     

Effect of deficit irrigation on drip-irrigated wheat grown in semi-arid conditions of Upper Egypt

Shortage of water in arid and semi-arid regions increases the need of applying efficient drip irrigation system. A two-year field study in the semi-arid region of Upper Egypt was carried in randomized complete block design with four replicates. Wheat plants were irrigated by 100 or 75% of water requirements (I₁₀₀ = 5,370 and I₇₅ = 4,027 m³ ha^?1). Irrigation of wheat by I₁₀₀ increased growth and uptake of nitrogen, phosphorus, and potassium compared to low irrigation level. I₁₀₀ caused 14 and 5% increase in straw and biological yield, respectively, compared to I₇₅. Grain yield and water use efficiency (WUE) were higher by 20 and 59% in the case of I₇₅ compared to I₁₀₀. The use of deficit irrigation in drip-irrigated wheat under arid conditions is an effective tool to maximize efficiency of water use; moreover, 4,027 m³ ha^?1 is the optimum irrigation rate for maximum WUE and grain yield.     

覆膜方式和滴灌带布设对春玉米根区土壤水氮均匀度及根冠生长及产量的影响

为探求不同覆膜方式及滴灌带布设对作物产量及收获系数的影响,设置不同滴灌带间距(A1:1 m;A2:0.5 m)与覆膜方式(M1:全覆盖;M2:半膜覆盖),通过2年田间试验研究其对根区土壤水氮分布均匀度(CU_w, CU_N)及春玉米根冠生长及产量的影响。结果表明:膜下滴灌条件下,根区土壤含水率与其分布均匀度具有一致性;高频滴灌施肥虽提高根区土壤NO₃^-含量却降低其分布均匀度,表现出不一致性。提高土壤水、氮分布均匀度未显著影响作物根长密度,但增加地上部叶面积,从而降低作物根冠面积比。相比滴灌带布设,覆膜方式对春玉米产量和收获系数的影响更为显著。低频灌溉条件下,全膜覆盖处理提高春玉米根区土壤水分和NO₃^-含量及均匀度,其作物产量较部分覆膜处理提高37.4%;而高频灌溉下,部分覆膜处理的作物产量较全膜覆盖处理提高7.7%。当根表面积与叶面积之比(RSA/LA)趋于4时,作物产量和收获系数最高,RSA/LA过高或过低均会降低作物产量和收获系数。综合考虑作物产量、收获系数和滴灌带成本,低频灌溉下建议选择A1M1处理,高频充分灌溉条件下建议选择A1M2处理。     

Conservation farming strategies in East and Southern Africa: Yields and rain water productivity from on-farm action research

Improved agricultural productivity using conservation farming (CF) systems based on non-inversion tillage methods, have predominantly originated from farming systems in sub-humid to humid regions where water is not a key limiting factor for crop growth. This paper presents evidence of increased yields and improved water productivity using conservation farming in semi-arid and dry sub-humid locations in Ethiopia, Kenya, Tanzania and Zambia. Results are based on on-farm farmer and research managed experiments during the period 1999–2003. Grain yield of maize (Zea mays L.) and tef (Eragrostis Tef (Zucc)) from conventional (inversion) tillage are compared with CF with and without fertilizer. Rain water productivity (WP_rain) is assessed for the locations, treatments and seasons. Results indicate significantly higher yields (p < 0.05) for CF+ fertilizer treatments over conventional treatments in most locations, increasing from 1.2 to 2 t ha^?1 with 20–120% for maize. For tef in Ethiopian locations, the yield gains nearly doubled from 0.5–0.7 to 1.1 t ha^?1 for “best bet” CF+ fertilizer. WP_rain improved for CF+ fertilizer treatments with WP gains of 4500–6500 m³ rainwater per t maize grain yield in the lower yield range from 0 to 2.5 t ha^?1. This is explained by the large current unproductive water losses in the on-farm water balance. There was a tendency of improved WP_rain in drier locations, which can be explained by the water harvesting effect obtained in the CF treatments. The experiences from East and Southern Africa presented in this paper indicate that for smallholder farmers in savannah agro-ecosystems, conservation farming first and foremost constitutes a water harvesting strategy. It is thus a non-inversion tillage strategy for in situ moisture conservation, rather than solely aimed at minimum tillage with mulch cover. Challenges for the future adoption of CF in sub-Saharan Africa include how to improve farmer awareness of CF benefits, and how to efficiently incorporate green manure/cover crops and manage weeds.     

秸秆覆盖条件下夏玉米田蒸散、水分利用效率和作物系数研究

Maize （Zea mays L.）, a staple crop grown from June to September during the rainy season on the North China Plain, is usually inter-planted in winter wheat （Triticum aestivum L.） fields about one week before harvesting of the winter wheat. In order to improve irrigation efficiency in this region of serious water shortage, field studies in 1999 and 2001, two dry seasons with less than average seasonal rainfall, were conducted with up to five irrigation applications to determine evapotranspiration, calculate the crop coefficient, and optimize the irrigation schedule with maize under mulch, as well as to establish the effects of irrigation timing and the number of applications on grain yield and water use efficiency （WUE） of maize. Results showed that with grain production at about 8 000 kg ha^-1 the total evapotranspiration and WUE of irrigated maize under mulch were about 380-400 mm and 2.0-2.2 kg m^-3, respectively. Also in 2001 WUE of maize with mulch for the treatment with three irrigations was 11.8% better than that without mulch. In the 1999 and 2001 seasons, maize yield significantly improved （P = 0.05） with four irrigation applications, however, further increases were not significant. At the same time there were no significant differences for WUE with two to four irrigation applications. In the 2001 season mulch lead to a decrease of 50 mm in the total soil evaporation, and the maize crop coefficient under mulch varied between 0.3-1.3 with a seasonal average of 1.0.     

单作与间作的棵间蒸发量差异及其主要影响因子

在甘肃河西走廊区, 通过大田试验, 研究了不同供水水平下小麦间作玉米与单作小麦、单作玉米的耗水量和棵间蒸发量差异, 探讨了影响作物棵间蒸发量的关键因子。结果表明, 小麦间作玉米的耗水量较单作小麦、单作玉米耗水量的平均值增加了41.44%~47.15%; 间作全生育期的总棵间蒸发量显著大于单作, 但间作的日均棵间蒸发量显著低于单作玉米、高于单作小麦; 间作的棵间蒸发量占总耗水量的比重显著低于单作玉米, 说明间作可提高农田水分利用的有效性。随灌水水平的提高,间作总耗水量显著增加,单作相邻灌水处理间的差异不显著;灌水水平对单作玉米、间作棵间蒸发量的影响不显著,说明间作耗水量增加主要是由蒸腾作用造成的。作物的日均棵间蒸发量与0~30 cm的土壤含水量、0~25 cm的土壤温度、全生育期的平均叶面积指数均呈显著正相关关系。单作玉米日均棵间蒸发量较大的主要原因是0~30 cm的土壤含水量、0~25 cm的土壤温度均相对较高。小麦间作玉米可提高作物的土地利用率, 其水分利用效率较单作平均提高25%以上。     

Nutrient Utilization Indices of NPK and Drought Management in Groundnut under Sandy Soil Conditions

ABSTRACT

In arid zones, farmers are obligated to reduce water amounts used in irrigating their lands. Consequently, reduction in final yields is realized. Thus, dealing with such a case became a decisive act. We tried to investigate the acceptable degree of lowering irrigation water with sustaining the productivity of groundnut as a way for managing drought conditions. Therefore, in summer seasons of 2016 and 2017 at the Experimental Research and Production Station, National Research Centre, Egypt, field trials were conducted with growing groundnut plants under three irrigation levels, i.e., 50%, 75%, and 100% of crop evapotranspiration (ET_c), denoted as I₅₀, I₇₅, and I₁₀₀, respectively. N, P, and K contents in seed and shoot and their yields in addition to harvest and partitioning indices were estimated. In spite of irrigating groundnut plants by normal water amounts, I₁₀₀, caused the maximum weight of seed biomass yield ha?1 and seed N and P contents, I75 was similar to I₁₀₀ for producing shoot biomass yield ha?1 and seed K content. Moreover, N and P yields (for shoots and seeds) and k yield (for seeds) showed the maximum values with I₁₀₀. Differences in all nutrient harvest indices (NHI, PHI, and KHI) between I₁₀₀ and I75 were not significant. Furthermore, I75 statistically leveled with I₁₀₀ in nutrient partitioning indices, viz., NPI, PPI, and KPI. In conclusion, groundnut straw residues produced by 25% less water supply than normal may share in managing drought stress by releasing nutrients and saving irrigation water in arid areas.     

Performance Assessment of Chlorophyll Meter to Determine When to Irrigate Wheat under Different Soil Moisture Deficit Conditions: An Initial Study

ABSTRACT

Proper irrigation timing can minimize the negative impacts that reduce crop yields. Therefore, in an initial pot experimental study, we assessed the SPAD (Soil–Plant Analysis Development)-chlorophyll meter as a tool to determine proper irrigation timing of wheat under different soil water deficit conditions in a controlled-environment greenhouse. The treatments were controlled irrigation at 100% (T₁), 70% (T₂), 50% (T₃) and 30% (T₄) of soil water content at field capacity; and the growth stages were development, mid-season and late-season. SPAD readings were measured pre-irrigation events. The results indicated that the T₃ and T₂ achieved maximum grain yield per accumulated crop evapotranspiration, i.e. water productivity (0.82 and 0.76 kg m^?3), and were at par with T₁. Moreover, the SPAD readings had a high Pearson’s correlation coefficient with crop evapotranspiration (r = 0.95; P ≤ 0.001) and wheat grain yield (r = 0.90; P ≤ 0.001), indicating that SPAD reading could be used to reliably estimate when to irrigate wheat. Therefore, T₃ and T₂ SPAD readings were averaged to estimate a target limit at which irrigation should be applied. Accordingly, the target limit was defined as >44.76 for the development stage, >50.72 for the mid-season stage, and >37.64 for the late-season stage; readings below this target limit indicate that it is time to irrigate.     

Response of Leek (Allium porrum L.) to Different Irrigation Water Levels Under Rain Shelter

A pot experiment was conducted to investigate the effects of different water levels on water-use efficiency, yield and growth parameters of leek (Allium porrum L.) and was carried out in the practical research field of Ondokuz May?s University in Turkey. Different irrigation water levels were based on the weight changes of each pot and included 5 irrigation treatments [25% (I₂₅), 50% (I₅₀), 75% (I₇₅), 100% (I₁₀₀) and 118% (I₁₁₈) times of consumed water]. Decreases in irrigation water resulted in decreases in plant height, stem diameter, leaf and stem fresh weights, leaf and stem dry weights and leaf area, but did not significantly affect leaf number or chlorophyll content. A yield-response factor of 1.26 was obtained, implying that the leek crop was sensitive to water stress caused by deficit irrigation. Comprehensive analysis of yield, water use efficiency, and evapotranspiration, the I₇₅ treatment can be suggested for leek production in water-scarce regions.     

绿洲灌区小麦水分生产率在不同尺度上的变化

水分生产率是衡量农业生产水平和农业用水科学性与合理性的综合指标。文章根据民乐县洪水河灌区1995-2006年的气象、灌溉用水量、灌溉面积、作物产量资料,从田间、斗渠、干渠、灌区4个不同尺度分析了小麦灌溉水分生产率年份间的变化情况。结果表明：不同尺度上平均灌溉水分生产率不同,田间尺度为1.414 kg/m3,斗渠尺度为1.013 kg/m3,干渠尺度为1.089 kg/m3,灌区尺度为0.894 kg/m3,并且不同尺度上的灌溉水分生产率在年份间的差异也比较大。2001年洪水河灌区实施了节水灌溉工程,不同尺度上的平均灌溉水分生产率在2001-2006年较1995-2000年有所提高,田间、斗渠、干渠、灌区分别提高了7.9%、19.4%、16.5%、7.4%,说明目前斗渠、干渠尺度上节水力度大,节水效益明显,而灌区尺度还有较大的节水潜力,应成为未来农业节水研究的重点。     

Changes in soil properties and their effects on maize productivity following<Emphasis Type="Italic"> Sesbania sesban</Emphasis> and<Emphasis Type="Italic"> Cajanus cajan</Emphasis> improved fallow systems in eastern Zambia

Improved fallows with leguminous trees have been developed in Southern Africa as a viable alternative to inorganic fertilizers but the changes in soil properties that are responsible for crop productivity improvement and implications of mixing litter and fresh leaves from the same tree species on soil fertility are not fully understood. Our objectives were to quantify (1) some changes in soil properties that are responsible for crop production improvement under improved fallow systems; (2) the N mineralization patterns of mixtures of litter and fresh leaves from the same tree species. The treatments used in the study were 2-year planted Sesbania sesban (sesbania) and Cajanus cajan (cajanus) and controls of natural fallow, continuous fertilized and unfertilized maize. At fallow clearing sesbania contributed 56 kg N ha^–1 through litter and fresh leaves. Sesbania (fresh leaves + litter) showed high N mineralization after 10 weeks compared to the mixture of cajanus fresh leaves with litter. Maize yields were significantly correlated with preseason NO₃^–-N and total inorganic-N content of the top 20-cm soil layer. Soil penetrometer resistance at 4 weeks after planting was lowest in the sesbania land-use system (2.2 Mpa), whereas the highest percentage of water-stable aggregates at fallow clearing and crop harvest was in sesbania (83%) and cajanus (77%), respectively. The improved soil conditions and N contribution of sesbania and cajanus fallows to the subsequent maize crop was evidenced by increased maize yields of between 170–200% over maize without fertilizer.     

基于水氮管理与种植结构优化的作物丰产高效管理策略

河西走廊农业生产受到水资源短缺与农业资源利用效率低的限制,制约着该地区的种子、粮食生产与农业可持续发展战略。该研究构建了考虑作物水氮需求量、降雨量、土壤初始含氮量的水氮管理制度优化方法,并结合所构建的考虑空间尺度作物产量与水氮利用效率的多目标种植结构优化方法,为河西走廊制种玉米、大田玉米和小麦制定丰产高效的水氮管理与种植结构调整策略,从而实现作物产量和水氮利用效率的协同提升。结果显示：优化的水氮管理制度相比管理现状可减少单位面积灌水量9.1%～27.3%、施氮量26.6%～50.0%;以作物产量和水氮利用效率最大为目标,以种植面积、产量需求和水氮投入量为约束,调整制种玉米、大田玉米和小麦的种植面积与空间分布,优化后制种玉米和小麦种植面积减少、大田玉米种植面积增加,总种植面积减少4 874.8 hm2,且作物种植空间分布较优化前差异明显;水氮管理与种植结构优化协同作用可以在水氮用量分别减少0.29×109 m3和3.36×107 kg的情况下,作物总产量提升0.16×109 kg,区域灌溉水生产力和氮肥利用效率分别提升0.62 kg/m3和18.97 kg/kg。该研究可以为产粮区和缺水区的作物丰产高效和农业可持续发展提供科学指导与决策参考。