Using EPIC model to manage irrigated cotton and maize

Simulation models are becoming of interest as a decision support system for management and assessment of crop water use and of crop production. The Environmental Policy Integrated Climate (EPIC) model was used to evaluate its application as a decision support tool for irrigation management of cotton and maize under South Texas conditions. Simulation of the model was performed to determine crop yield, crop water use, and the relationships between the yield and crop water use parameters such as crop evapotranspiration (ETc) and water use efficiency (WUE). We measured actual ETc using a weighing lysimeter and crop yields by field sampling, and then calibrated the model. The measured variables were compared with simulated variables using EPIC. Simulated ETc agreed with the lysimeter, in general, but some simulated ETc were biased compared with measured ETc. EPIC also simulated the variability in crop yields at different irrigation regimes. Furthermore, EPIC was used to simulate yield responses at various irrigation regimes with farm fields’ data. Maize required ∼700 mm of water input and ∼650 mm of ETc to achieve a maximum yield of 8.5 Mg ha⁻¹ while cotton required between 700 and 900 mm of water input and between 650 and 750 mm of ETc to achieve a maximum yield of 2.0-2.5 Mg ha⁻¹. The simulation results demonstrate that the EPIC model can be used as a decision support tool for the crops under full and deficit irrigation conditions in South Texas. EPIC appears to be effective in making long-term and pre-season decisions for irrigation management of crops, while reference ET and phenologically based crop coefficients can be used for in-season irrigation management.     

Agronomic and economic response to furrow diking tillage in irrigated and non-irrigated cotton (Gossypium hirsutum L.)

The Southeast U.S. receives an average of 1300 mm annual rainfall, however poor seasonal distribution of rainfall often limits production. Irrigation is used during the growing season to supplement rainfall to sustain profitable crop production. Increased water capture would improve water use efficiency and reduce irrigation requirements. Furrow diking has been proposed as a cost effective management practice that is designed to create a series of storage basins in the furrow between crop rows to catch and retain rainfall and irrigation water. Furrow diking has received much attention in arid and semi-arid regions with mixed results, yet has not been adapted for cotton production in the Southeast U.S. Our objectives were to evaluate the agronomic response and economic feasibility of producing cotton with and without furrow diking in conventional tillage over a range of irrigation rates including no irrigation. Studies were conducted at two research sites each year from 2005 to 2007. Irrigation scheduling was based on Irrigator Pro for Cotton software. The use of furrow diking in these studies periodically reduced water consumption and improved yield and net returns. In 2006 and 2007, when irrigation scheduling was based on soil water status, an average of 76 mm ha⁻¹ of irrigation water was saved by furrow diking, producing similar cotton yield and net returns. Furrow diking improved cotton yield an average of 171 kg ha⁻¹ and net return by $245 ha⁻¹ over multiple irrigation rates, in 1 of 3 years. We conclude that furrow diking has the capability to reduce irrigation requirements and the costs associated with irrigation when rainfall is periodic and drought is not severe.     

亏缺灌溉对南疆棉花生长和水分利用的影响

针对南疆地区水资源短缺、作物水分利用效率低等问题,以棉花为试验材料进行田间小区试验,在棉花现蕾期、开花期以及结铃期分别设置3个亏缺灌溉水平(W₁:50%ET_c,W₂:65%ET_c,W₃:80%ET_c,ET_c为作物蒸发蒸腾量),以全生育期100%ET_c灌溉处理为对照(CK),研究膜下滴灌条件下,不同生育期亏缺灌溉对棉花生长、产量、氮素吸收和水分利用效率的影响.结果表明:现蕾期亏水对棉花株高、叶面积指数、地上干物质生长、氮素吸收和产量有不同程度的抑制效应,但复水后补偿效应显著,其中轻度亏水(W₃)在籽棉产量减少3.48%的条件下,WUE高达1.57 kg/m³,显著高于CK的1.48 kg/m³;开花期亏水,棉花的各项生长指标均有显著降低,复水后补偿效应不显著,不利于棉花生长发育;结铃期亏水对棉花地上干物质累积、氮素吸收和产量均有显著的抑制效应,但在W₂和W₃水平下,WUE均达1.51 kg/m³.综合考虑在保证棉花产量的同时达到节水增产的目的,可在棉花蕾期进行80%ET_c灌水,其他生育阶段实施充分灌溉,来控制营养生长,促进生殖生长,获得更高的水分利用效率.     

澳大利亚棉花地下滴灌技术

随着水资源的短缺以及人们对农业可持续发展的认识，地下滴灌(SDI)已经成为世界各国研究和应用的热点。目前，SDI在美国、法国、日本、澳大利亚等已有较大面积应用，在一些严重缺水的国家和地区，如中东地区的部分国家也得到应用，我国地下滴灌的研究刚刚起步。分别从地下滴灌的设计、安装、管理和经济效益角度，介绍了地下滴灌在澳大利亚棉花上应用情况。重点分析了滴灌带的布置方式、设计耗水强度、过滤器选择和出苗问题以及地下滴灌对棉花产量的影响。     

隔沟交替灌溉研究进展

隔沟交替灌溉是以通过改善作物根信号功能、光合作用、蒸腾作用和气孔导度等生理特性,进而提高作物产量为目的的一项高效节水灌溉技术。介绍了隔沟交替灌溉技术发展概况,系统阐述隔沟交替灌溉的作用机理,主要包括根系系统的吸收补偿功能、农田土壤水分消耗和水分利用效率变化3个方面,明确了该技术在作物栽培中的应用效果与发展前景。隔沟交替灌溉可显著提高作物产量和水分利用效率,在优质高产节水型农业生产中具有重要意义。      

Analysing farming practices to develop a numerical,operational model of farmers’ decision-making processes: An irrigated hay cropping system in France

Conventional water management in the Crau plain needs to be modified to ensure higher irrigation efficiency, better crop production and quality, and reduced environmental impacts. Because experimental approaches to test modifications of water management are difficult in relation to border irrigation, simulation may provide an alternative. We describe the development of a conceptual model of the decision-making process that determines the irrigation management of a cropping system, on which a simulation model is to be based. Interviews focused on water management were carried out, to understand how farmers manage their irrigation and how their decisions determine the technical system applied on the farm. These interviews were then analyzed using the “model for action” concept, to generate a conceptual model of the decision system, which is organized as a sequence of decision rules describing irrigation management. This model contains five elements: (1) spatial and temporal factors relevant to decision-making in terms of irrigation and hay cropping; (2) no interaction between the grassland cropping system and the sheep rearing system; (3) five rules to describe irrigation management in the cropping system; (4) major water distribution constraints; and (5) two inter-related operations, hay mowing and irrigation. The rules for irrigation decision-making are written as: “If <Indicator><Operator><Threshold> Then <Action1> Else <Action2>”. This conceptual model was used as the basis of a decision support system that includes models of grass growth and hydrology.     

利用气象资料指导膜下滴灌棉花灌溉的试验研究

利用气象资料指导膜下滴灌棉花灌溉的试验于2007年5~10月份在新疆生产建设兵团灌溉中心试验站的试验基地进行。试验共设置7个处理,分别按生育期ET0的不同比例进行灌水。试验结果表明,为了获得经济合理的产量,膜下滴灌棉花全生育期耗水量应控制在360~405 mm之间。用实时气象资料指导膜下滴灌棉花的灌溉具有很好的可行性,蕾期和花铃后期10 d灌1次水,灌水定额为60%ET0;花铃前期7 d灌1次水,灌水定额为75%ET0,是一种适宜北疆地区膜下滴灌棉花的灌水模式。     

灌水模式及下限对滴灌棉花产量和品质的影响

为探索滴灌条件下棉花优质高效灌溉指标,在新疆石河子研究了地下滴灌(SSDI)和膜下滴灌(SDI)条件下不同灌水控制下限对棉花耗水量、品质以及水分利用率的影响.结果表明,相同滴灌模式,棉花蕾期耗水量随灌水控制下限的提高而增加,花铃期水分胁迫处理的棉花阶段耗水量普遍低于对照处理;蕾期适度水分胁迫(灌水控制下限为60% FC)花铃期充分供水(灌水控制下限为75% FC)处理(SDI-7和SSDI-7)有利于籽棉产量的提高,与对照处理相比,籽棉产量提高了14.48%(SDI-7)和11.60%(SSDI-7);水分处理对棉花衣分、棉纤维整齐度的影响不明显,蕾期和花铃期水分胁迫对棉纤维上半部平均长度的影响随水分胁迫程度的加重而加剧,蕾期适度水分胁迫(灌水控制下限为60% FC)有利于棉纤维断裂比强度的提高.相同水分处理,地下滴灌棉花产量和灌溉水利用率均高于膜下滴灌棉花.与对照处理相比,蕾期和花铃期灌水控制下限分别为60% FC和75% FC,灌水定额为30 mm处理在节约灌溉水的同时提高了籽棉产量并改善了棉纤维品质,可作为石河子垦区滴灌棉花适宜的灌水指标.     

Yield and water use efficiency of wheat and cotton under alternate furrow and check-basin irrigation with canal and tube well water in Punjab, India

A 4-year field experiment was conducted in a semi-arid area to evaluate the response of each furrow and alternate furrow irrigation in wheat-cotton system using irrigation waters of different qualities in a calcareous soil. Irrigation was applied to each and alternate furrow of bed-planted wheat followed by ridge-planted cotton for comparison with standard check-basin method of irrigation to both the crops. These methods of irrigation were evaluated under three water qualities namely good quality canal water (CW), poor quality tube well water (TW) and pre-sowing irrigation to each crop with CW and all subsequent irrigations with TW (CWpsi + TW). The pooled results over 4 years revealed that wheat grain yield was not affected significantly with quality of irrigation water, but significant yield reduction was observed in alternate bed irrigation under canal water and tube well water irrigations. In cotton, poor quality tube well water significantly reduced the seed cotton yield in all the three methods of planting. The pre-sowing irrigation with canal water and all subsequent irrigations with tube well water improved the seed cotton yield when compared with tube well water alone. However, this yield increase was significant only in alternate furrow irrigation, and the yield obtained was on a par with yield under alternate furrow in CW. When compared to check-basin irrigation, each furrow and alternate furrow irrigation resulted in a saving of 30 and 49% of irrigation water in bed-planted wheat, whereas the corresponding savings in ridge-planted cotton were 20 and 42%, respectively. Reduced use of irrigation water under alternate furrow, without any significant reduction in yield, resulted in 28.1, 23.9 and 43.2% higher water use efficiency in wheat under CW, TW and CWpsi + TW, respectively. The corresponding increase under cotton was 8.2, 2.1 and 19.5%. The implementation of alternate furrow irrigation improved the water use efficiency without any loss in yield, thus reduced use of irrigation water especially under poor quality irrigation water with pre-sowing irrigation with canal water reduced the deteriorating effects on yield and soil under these calcareous soils.     

基于两线解码技术的水肥一体化云灌溉系统研究

针对传统设施农业水肥利用效率低、信息采集量少、数据挖掘利用弱等问题,设计了基于两线解码技术和云计算的设施农业水肥一体化智能云灌溉系统,包括智能云灌溉控制系统、全自动水肥一体机和高效节水灌溉系统3部分。该系统通过两线解码技术,利用各种传感器实时采集各单个设施农业作物生长环境的参数信息,并将各类采集数据及时传输和存储于数据管理云平台,根据设施农业种植区采取的环境信息和作物的需水需肥规律,利用云集群的计算和分析能力,科学确定设施农业中不同环境条件下作物生长的水肥需求和灌溉施肥制度,实现水肥一体化的智能控制。通过2个设施农业种植基地的应用实例表明,相比传统灌溉方式,水分和肥料的利用率分别提高了25%~40%和15%~35%,并且大幅度减少了劳动时间和劳动力。     

基于遥感的农业用水效率评价方法研究进展

遥感技术的发展为区域尺度蒸散发计算、作物分布识别及估产提供了一条有效途径,为基于遥感信息的灌区灌溉水利用效率及作物水分利用效率定量评价奠定了基础。回顾总结了遥感蒸散发模型、瞬时蒸散发升尺度方法、日蒸散发插值方法、作物分布识别方法及作物估产模型的研究进展,评述了遥感蒸散发及作物估产结果在灌区灌溉水利用效率及作物水分利用效率评价中的应用情况。提出了相关领域需要进一步研究的问题,包括适合非均匀下垫面特点且具有较强物理基础的灌区遥感蒸散发模型、日蒸散发插值中灌溉或降雨引起土壤含水量突变情况的处理、农田蒸散发中灌溉水有效消耗量的准确估算、能适应复杂种植结构并且适用于多年的作物分布遥感识别模型以及精度较高且可操作性强的遥感估产模型等。     

CPSP模型在华北井灌区农业水管理中的应用

为研究不同农业水管理措施对区域水平衡的影响,选择北京市大兴区为华北井灌区代表性研究区,以CPsP模型为技术支持,研究了提高灌溉水利用率、采用亏缺灌溉、改善农业种植结构及利用区外水源等不同水管理措施影响下区域水平衡、区域耗水、区域取水及用水指标的变化规律.结果表明,在资源型缺水区域,提高灌溉水利用率、采用非充分灌溉及改善农业种植结构在一定程度上能缓解区域水资源紧缺的压力,特别是采用非充分灌溉及改善作物种植结构能显著减少区域取水及耗水总量,并能减少地表水及地下水的补给量中回归水所占比例,在缓解区域水资源紧缺压力的同时也降低了区域水质遭受回归水污染风险.另外,在未来情景中,因经济快速发展及人口持续增长,工业及居民生活用水量增加,区域水资源供需矛盾将会加剧,为确保区域水资源良性循环,势必采取积极有效的水资源管理模式.     

A comparative analysis of water application and energy consumption at the irrigated field level

Most government policies and community perception of the irrigation sector promotes the conversion from gravity-fed to pressurised irrigation methods as a way of reducing water consumption by the irrigation sector. However, optimising for one aspect of a system can have unintended resource and environmental consequences e.g. an increase in energy consumption patterns of irrigated crops. Two Australian irrigation areas were studied: a surface-water supplied region in New South Wales; and a groundwater dependent region in South Australia. The water and energy budgets for crop production from land preparation to harvest were quantified on several farms. Converting from flood to pressurised systems resulted in a reduction in water application of between 10% and 66%. However, in the surface-water supplied region, it also resulted in energy consumption being increased by up to 163%. In the groundwater dependent region, energy consumption was reduced by 12% to 44%. There is potential to reduce energy consumption due to increased water use efficiency, resulting in less water being pumped due to efficiency gains. Therefore, to optimise energy and water use, it is recommended that pressurised irrigation systems be used in areas requiring pressurised extraction of groundwater, while efficient gravity based irrigation methods, coupled with good management practices, be promoted in surface-water supplied areas.     

Subsurface drip irrigation of onions: Effects of drip tape emitter spacing on yield and quality

Improved irrigation water use efficiency is an important component of sustainable agricultural production. Efficient water delivery systems such as subsurface drip irrigation (SDI) can contribute immensely towards improving crop water use efficiency and conserving water. However, critical management considerations such as choice of SDI tube, emitter spacing and installation depth are necessary to attain improved irrigation efficiencies and production benefits. In this study, we evaluated the effects of subsurface drip tape emitter spacing (15, 20 and 30 cm) on yield and quality of sweet onions grown at two locations in South Texas—Weslaco and Los Ebanos. Season-long cumulative crop evapotranspiration (ETc) was 513 mm in Weslaco and 407 mm at Los Ebanos. Total crop water input (rain + irrigation) at Weslaco was roughly equal to ETc (92% ETc) whereas at Los Ebanos, water inputs exceeded ETc by about 35%. Onion yields ranged from 58.5 to 70.3 t ha⁻¹ but were not affected by drip tube emitter spacing. Onion pungency (pyruvic acid development) and soluble solids concentration were also not significantly influenced by treatments. Crop water use efficiency was slightly higher at Weslaco (13.7 kg/m³) than at Los Ebanos (11.7 kg/m³) partly because of differences in total water inputs resulting from differences in irrigation management. The absence of any significant effects of drip tape emitter spacing on onion yield may be due to the fact that irrigation was managed to provide roughly similar irrigation amounts and optimum soil moisture conditions in all treatments.     

施氮对中国棉田产量和水分利用效率影响的Meta分析

为系统分析不同气候条件、土壤基础条件和农田管理措施条件下施氮对棉花产量和水分利用效率的影响,收集了国内外已发表的103篇中英文文献,筛选其中37篇文献,共获得301组产量和127组水分利用效率数据。基于Meta分析方法定量分析了不同生产条件下施氮对棉花产量和水分利用效率的影响,同时利用偏相关分析找出施氮条件下棉花产量和水分利用效率的主要影响因素。结果表明,以不施氮为对照,施氮能够显著提高棉花的产量和水分利用率。在年均降水量200～500 mm的地区施氮对产量和水分利用率的提高作用最为明显,效应量分别为34.02%和54.15%;施氮对产量和水分利用率的提高作用均随着日照时数的增大而增大。当土壤pH值为6～8时,施氮对棉花产量和水分利用效率的提高作用最为明显,效应量分别为28.52%和24.59%;在不同土壤质地中施氮对产量和水分利用效率的提高作用均表现为在砂土中效应量最大,分别为46.71%和26.29%;随着施肥频次的增加,施氮对棉花产量和水分利用率的提高作用逐渐增大;施氮对产量的提高作用随灌水量的增加而增加,对水分利用率的提高作用随灌水量的增加呈先增加后降低趋势。当施氮量为300～...     

A package of water management practices for sustainable growth and improved production of vegetable crop in labour and water scarce Sub-Saharan Africa

A package of water management practices including pitcher irrigation method and water conserving techniques of manure application and mulching is experimented for sustainable growth and improved production of cucumber crop in Makanya village in North Eastern Tanzania. The increase in total yield due to package of water management practices is 203 per cent and water use efficiency obtained is 12.06 kg m⁻³. The seasonal water requirement of cucumber crop under package of water management practices ranges from 146.30 to 198.10 mm, which is on an average 4.19 times less as compared to control treatment of can irrigation. The irrigation interval in package of water management practices is 4.9 times higher than the can irrigation method. The water and labour uses are reduced by 75.9 and 73 per cent, respectively in package of water management practices. The results showed that the self-regulative nature of pitchers and moisture retention by water conserving techniques is helpful in mitigating water stress in crop root zone. The moisture retention period in soil is increased assisting reduction of labour hours required in irrigation. In local context, the water management practices included in the package are easy to understand, adopt, operate and maintain.     

地面灌水技术优化组合节水高产机理研究

对不同地面灌水技术进行优化组合应用,根据全年作物连作的需水特点实施调亏灌溉使土壤水分消长过程在节水高产调控范围内,提高了水分效应,小麦和棉花水分生产效率达１．５３ｋｇ／ｍ３和０．４１ｋｇ／ｍ３的较高水平。同时还对其节水高产机理进行了探讨,为节水高产的地面灌水技术优化组合应用提供了科学依据。     

小流量微压滴灌条件下作物生长试验研究

通过盆栽线辣椒试验,研究了不同的滴头流量、灌水定额及灌水周期对线辣椒的株高、茎粗、叶绿素的相对含量、光合作用、产量及水分利用效率的影响,结果表明,小流量滴灌能提高线辣椒的叶绿素含量,促进光合作用,增加坐果数,并能提高其产量和水分利用效率;采用小灌水定额高频率灌溉对于抑制地表无效蒸发作用显著,节水效果明显,建议在小流量微压滴灌条件下,采用小定额高频率灌溉制度。     

膜下滴灌棉花田间需水规律研究

以田间试验为基础对膜下滴灌棉花的田间需水规律进行了对比研究 ,从土壤 -作物 -大气连续体的角度对该技术下影响棉花耗水的主要因素进行了分析 ,找到了膜下滴灌比沟灌省水的依据 ,同时发现对棉花采用膜下滴灌技术可改善需水量在各生育阶段的合理分配 ,提高叶面积指数 LAI,从生理上提高了作物水分利用率及增产潜力