Simulating the Impacts of Irrigation Levels on Soybean Production in Texas High Plains to Manage Diminishing Groundwater Levels

There is an increasing need to strategize and plan irrigation systems under varied climatic conditions to support efficient irrigation practices while maintaining and improving the sustainability of groundwater systems. This study was undertaken to simulate the growth and production of soybean [Glycine max (L.)] under different irrigation scenarios. The objectives of this study were to calibrate and validate the CROPGRO‐Soybean model under Texas High Plains’ (THP) climatic conditions and to apply the calibrated model to simulate the impacts of different irrigation levels and triggers on soybean production. The methodology involved combining short‐term experimental data with long‐term historical weather data (1951–2012), and use of mechanistic crop growth simulation algorithms to determine optimum irrigation management strategies. Irrigation was scheduled based on five different plant extractable water levels (irrigation threshold [ITHR]) set at 20%, 35%, 50%, 65%, and 80%. The calibrated model was able to satisfactorily reproduce measured leaf area index, biomass, and evapotranspiration for soybean, indicating it can be used for investigating different strategies for irrigating soybean in the THP. Calculations of crop water productivity for biomass and yield along with irrigation water use efficiency indicated soybean can be irrigated at ITHR set at 50% or 65% with minimal yield loss as compared to 80% ITHR, thus conserving water and contributing toward lower groundwater withdrawals. Editor's note: This paper is part of the featured series on Optimizing Ogallala Aquifer Water Use to Sustain Food Systems. See the February 2019 issue for the introduction and background to the series.     

OPTIMUM DESIGN OF BORDER IRRIGATION SYSTEM1

ABSTRACT: Border irrigation systems like most of the other surface irrigation systems, do not need too much energy and special equipment. Thus, many farmers have used this system for a long time. On the other hand, design of surface irrigation systems including border irrigation requires many input parameters, and need intensive engineering calculations. The burden of these requirements probably led the users to experimental design of the systems with low efficiencies. However, accurate design and high quality optimization of the border irrigation system that can result in a highly efficient system is possible. In this study, an optimization model for border irrigation system is presented. The Hook Jeev's pattern search optimization method in conjunction with a general mathematical model of border irrigation is used to maximize the irrigation application efficiency. The border irrigation storage and distribution efficiencies, border slope and length, inflow rate, cutoff time, and the Manning's roughness coefficient are selected as constraints. The model is applied to field-measured data. The results show that it is possible to select a suitable combination of the border system's parameters (border's length, inflow rate, and cutoff time) to obtain a maximum application efficiency.     

Valuing Improvements in The Water Rights System in South Africa: A Contingent Ranking Approach1

Speelman, Stijn, Stefano Farolfi, Aymen Frija, and Guido Van Huylenbroeck, 2010. Valuing Improvements in the Water Rights System in South Africa: A Contingent Ranking Approach. Journal of the American Water Resources Association (JAWRA) 46(6):1133–1144. DOI: 10.1111/j.1752-1688.2010.00480.x Abstract: In the context of increasing water scarcity, understanding is growing that irrigation water rights are important and that a lack of an effective water rights system constitutes a major reason for inefficient water management. This study carried out a contingent ranking experiment to study how smallholder irrigators in South Africa would value potential changes in water rights. Three specific dimensions of water rights, relevant for the South African case, are considered: duration, quality of title, and transferability. Results indicate that smallholder irrigators are prepared to pay considerably higher water prices if improvements are made in the water rights system. This implies that the proposed interventions in the water rights system would improve the efficiency and productivity of the small-scale irrigation sector. The increased willingness to pay could furthermore also assist the South African government to reach the objective of increased cost recovery.     

CONSTRAINTS IN WATER MANAGEMENT ON AGRICULTURAL LANDS1

ABSTRACT Whether the goal is minimizing water quality degradation in receiving streams or maximizing agricultural production on existing croplands; the solutions are identical - improved water management practices. Technology has succeeded in developing feasible solutions to improving irrigation water management, but the law has been slow to encourage or direct implementation. The villain of the western United States water problem is the property right concept of the appropriation doctrine. Improving water management also implies organizational improvements. Also, the so-called “human factor” involves questions of inefficiency and ineffectiveness, that when examined under the criteria of efficacy, may dictate a policy of continuing present practices in certain localities or regions with little technological intervention. The present effort for improving water quality management implies, therefore, a manyfold attack aimed at increasing project irrigation efficiency and effectiveness, under the larger rubric of efficacy and the achievement of larger social goals.     

Understanding farmer intentions to connect to a modernised delivery system in an Australian irrigation district: a reasoned action approach

Australian governments have sought to invest in irrigation infrastructure to improve the efficiency of water delivery to rural properties and improve water supply and on-farm efficiency. A programme of rationalising irrigation infrastructure has attracted criticism and doubts about its likely success. Attitude theory in the form of the Reasoned Action Model was applied to understand the intentions of landowners to connect to a ‘modernised’ irrigation system. Attitudes towards connecting to the system, social norms and perceptions of control over the behaviour provided an explanation of intentions to connect. Actual financial capability and other variables were important in discriminating a group of landowners who had already connected to the modernised system from farmers who had not.     

NEW METHODS OF MODELING WATER AVAILABILITY FOR AGRICULTURE UNDER CLIMATE CHANGE: THE U.S. CORNBELT1

ABSTRACT: This paper reports on new methods of linking climate change scenarios with hydrologic, agricultural an water planning models to study future water availability for agriculture, an essential element of sustainability. The study is based on the integration of models of water supply and demand, and of crop growth and irrigation management. Consistent modeling assumptions, available databases, and scenario simulations are used to capture a range of possible future conditions. The linked models include WATBAL for water supply; CERES, SOYGRO, and CROPWAT for crop and irrigation modeling; and WEAP for water demand forecasting, planning and evaluation. These models are applied to the U.S. Cornbelt using forecasts of climate change, agricultural production, population and GDP growth. Results suggest that, at least in the near term, the relative abundance of water for agriculture can be maintained under climate change conditions. However, increased water demands from urban growth, increases in reservoir evaporation and increases in crop consumptive use must be accommodated by timely improvements in crop, irrigation and drainage technology, water management, and institutions. These improvements are likely to require substantial resources and expertise. In the highly irrigated basins of the region, irrigation demand greatly exceeds industrial and municipal demands. When improvements in irrigation efficiency are tested, these basins respond by reducing demand and lessening environmental stress with an improvement in system reliability, effects particularly evident under a high technology scenario. Rain-fed lands in the Cornbelt are not forced to invest in irrigation, but there is some concern about increased water-logging during the spring and consequent required increased investment in agricultural drainage. One major water region in the Cornbelt also provides a useful caveat: change will not necessarily be continuous and monotonic. Under one GCM scenario for the 2010s, the region shows a significant decrease in system reliability, while the scenario for the 2020s shows an increase.     

Use of Predictive Weather Uncertainties in an Irrigation Scheduling Tool Part I: A Review of Metrics and Adjoint Methods

Irrigation management consists of many components. In this work we review and recommend rainfall forecast performance metrics and adjoint methodologies for the use of predictive weather data within the Colorado State University Water Irrigation Scheduler for Efficient Application (WISE). WISE estimates crop water uses to optimize irrigation scheduling. WISE and its components, input requirements, and related software design issues are discussed. The use of predictive weather allows WISE to consider economic opportunity‐costs of decisions to defer water application if rainfall is forecast. These capabilities require an assessment of the system uncertainties and use of weather prediction performance probabilities. Rainfall forecasts and verification performance metrics are reviewed. In addition, model data assimilation methods and adjoint sensitivity concepts are introduced. These assimilation methods make use of observational uncertainties and can link performance metrics to space and time considerations. We conclude with implementation guidance, summaries of available data sources, and recommend a novel adjoint method to address the complex physical linkages and model sensitivities between space and time within the irrigation scheduling physics as a function of soil depth. Such tool improvements can then be used to improve water management decision performance to better conserve and utilize limited water resources for productive use. Editor’s note : This paper is part of the featured series on Optimizing Ogallala Aquifer Water Use to Sustain Food Systems. See the February 2019 issue for the introduction and background to the series.     

PRIVATIZING GOVERNMENT IRRIGATION PROJECTS IN NEW ZEALAND1

ABSTRACT: This paper discusses the sale of the Government. owned irrigation projects in New Zealand, including the development of irrigation projects in New Zealand, the rationale behind the transfer of ownership to existing irrigators, the sale process, and the outcomes. The transfer of ownership to private entities was undertaken primarily to remove the Government from irrigation activities. However, the sales were also thought to have the poten. tial to improve the efficiency of the projects' operation. The sale process was a negotiated process so that maximizing revenues was not the primary objective of the government. In many cases the government paid irrigators to assume ownership of the schemes. Preliminary data suggest that schemes are being more efficiently operated under private ownership. However, additional data need to be collected on a systematic basis to determine the magnitude of any efficiency gains.     

POLLUTION OF SURFACE IRRIGATION WATERS BY PLANT PATHOGENIC ORGANISMS1

ABSTRACT: Systematic sampling of waterways and irrigation runoff from agricultural lands in the North Platte Project of Nebraska in July and August of 1972–1974 demonstrated that phytopathogenic organisms were disseminated. The organisms monitored included the bean common blight bacterium Xanthomonas phaseoli, the bean white mold fungus Whetzelinia sclerotiorum and various nematodes. Although many types of nematodes often were recovered from irrigation water, Heterodera sp. cysts which cause significant disease problems in the valley were found infrequently. Patterns of movement of the bacterial and fungal organisms were correlated with previous or current season infection of bean plants. The short-term survival of X. phaseoli in sterile deionized water may explain the detection of this organism only in runoff or ditches receiving runoff from common blight infected bean fields. Sclerotial bodies of W. sclerotiorum remained viable for at least 10–21 days in flowing water and were found throughout the irrigation waterways. Irrigation of beans with contaminated water can result in both common blight and white mold diseases. Dissemination of phytopathogenic organisms in irrigation reuse systems as well as agricultural land runoff should be considered in irrigation planning and system design.     

Alternate wet and dry irrigation technology as a sustainable water management and disease vector control tool

Rising population and demands for rice as a staple food have created severe stress on freshwater availability for paddy cultivation. The literature suggests that conventional irrigation techniques are inadequate to overcome the water constraints arising from drought and extreme weather conditions. In the past few decades, there is an upsurge of scientific exploration of agricultural techniques in reinventing traditional methods of irrigation. Recently, alternate wet and dry irrigation (AWDI) method has shown great promise regarding profitable rice cultivation with limited water supply. The AWDI method is a trending water management system, which inundates rice fields with intermittent wet conditions followed by a dry period. This not only ensures adequate water supply but increases crop yield and water productivity index (WPI). The AWDI also helps in reducing parasitic mosquito population in the rice fields by minimizing the field flooding period and curtailing a major part of their life cycles. This review proposes a novel approach of emphasizing AWDI method as an important agricultural tool for supplementing rice fields with limited freshwater, increasing crop yield, and monitoring parasitic mosquito populations. The major objective of this study is to report the state-of-the-art scenario of AWDI method, critically analyze the research gaps related to conventional methods of irrigation and appreciate the futuristic long-term benefits of AWDI method. Literature survey was performed using search engines like Scopus, PubMed, Google Scholar, Research Gate, Science Direct, and Google Scholar. Comprehensive appraisal of resources (both offline and online) and critical evaluation of AWDI technicalities revealed that the AWDI reduced water usage by 45%, enhanced crop yield and improved WPI in paddy fields in the Asian sub-continent. The AWDI also curtailed the propagation of lethal mosquito species (Cx. tritaenorhynchus, Cx. vishnui, and Cx pseudovishnui) in rice fields. Therefore, the current study endorses AWDI as a promising substitute of conventional irrigation and a novel approach towards fulfilling water constraints that may be practiced anywhere in the world.     

THE IMPORTANCE OF INSTITUTIONAL STRUCTURE IN CONTROLLING AGRICULTURAL RUNOFF1

Abstract: Agricultural runoff, such as dissolved mineral salts and selenium, creates pronounced downstream impacts to agricultural producers and to wildlife. The ability to manage these problems efficiently depends critically on the institutional pricing structure of irrigation water delivery agencies. An important characteristic of irrigation water delivery is whether irrigators pay per unit of water received or make one payment regardless of the quantity of water received. In this study we compare the effectiveness of agricultural runoff reduction policies in two regions that employ these different water pricing structures. We find that reduction policy is more effective and can be achieved at a lower cost when water is priced on a per unit basis and that growers have greater incentive to act on their own to reduce runoff problems. Operating under a per unit pricing system encourages water conservation and runoff reduction, which creates public benefits that are not achieved under the single-payment, fixed allotment method of irrigation water delivery.     

TECHNICAL AND INSTITUTIONAL ASPECTS OF SEWAGE EFFLUENT-IRRIGATION WATER EXCHANGE,TUCSON REGION1

ABSTRACT .Many growing municipalities near irrigated agriculture are advocating a transfer of water now utilized for irrigation to municipal use. Alternatives are presented whereby this water can be transferred to municipal use in exchange for treated sewage effluent. The irrigation water would in effect be cycled through the municipal system prior to use on the farms. A case study of the Tucson region illustrates the relevant legal, economic and technical aspects. Effluent could be delivered to irrigators in Avra Valley at a cost less than that now paid for water pumped from declining water tables. In return the City of Tucson could import ground water now being used for irrigation through an existing pipeline which presently cannot be used because of a court injunction obtained by the irrigators. It appears that such an exchange agreement could be made without modification of existing statutory law. Similar exchange arrangements may prove to be feasible in other regions containing irrigated agriculture. Increased efficiency of water use can be achieved avoiding external effects which commonly arise in a direct transfer and are difficult to evaluate. High quality water is allocated to municipal use whereas nutrient-rich sewage effluent is transferred to irrigation.     

A study on operation problems of hydropower plants integrated with irrigation schemes operated in Turkey

In this study, Hydroelectric Power Plants, which have been built and integrated with irrigation schemes by the State Hydraulic Works which is a government agency and private companies in Turkey, have been examined. Technical, environmental, structural and social problems encountered during their operation have been analyzed, and appropriate solution proposals have been presented in the study for a sustainable irrigation and Hydroelectric Power Plant operation. Consequently, Hydroelectric Power Plants which have been integrated with irrigation schemes should be operated efficiently and they should be operated in attenuation with the environment. However, when hydroelectric projects are developed without preparing their necessary integrated basin management plans, then this will cause environmental, operation and maintenance, administrative, monitoring and evaluation problems. In order to ensure sustainability of hydroelectricity production and also in order to use water resources more efficiently for irrigation; it is very important to find permanent solutions to these problems.     

渗灌——设施园艺先进的节水灌溉技术

渗灌具有降低室内湿度、改善土壤环境、节约灌溉用水、减少肥料用量、省工省时、价格适中等优点,是目前设施园艺先进的节水灌溉技术。详细介绍了渗灌系统的结构,渗灌管的种类以及使用维护方法。     

Performance analysis of on-farm irrigation tanks on agricultural drainage water reuse and treatment

Water reuse and pollutant removal efficiency analysis of the on-farm irrigation tanks (OFTs) was carried out in rice paddy field region of Zhanghe Irrigation District, Southern China through field experiments during the rice growing season of 2009–2011. Water flow measurements indicate that 20.6–68.9% of drainage water captured by OFTs was reused for supplemental irrigation. Rainfall was the most important factor that determines the water reuse efficiency (WRR) of OFTs, since higher rainfall resulted in higher surplus irrigation water draining out of OFTs without reuse, and thus decreased WRR. Fully using the storage capacity for storing return flow, and releasing totally for supplemental irrigation also enhanced WRR of OFTs. Water quality analysis shows that OFTs removed 47.2% of total phosphorous (TP) and 60.8% of total nitrogen (TN) of inflow and have a great effect on increasing sedimentation for return flow as the mean of removal efficiency of pollutant load (REL) for suspended solids (SS) amounted to 68.4%. For water treatment effectiveness of OFTs, high hydraulic retention time (HRT) is most beneficial to increase REL of TN whereas REL of TP is not sensitive to HRT. These results confirm that OFTs can effectively increase agricultural return flow reuse and remove pollutants. As the cascade OFTs irrigation system recycle return flow for several times, the irrigation water demand from outside of region was reduced significantly for rice production. Coupling with the effect of cyclic irrigation on the nutrients recycling by paddy fields, OFTs irrigation system also considerably mitigate the N and P off-site emission. Therefore, it is advisable to integrate the role of OFTs on water reuse and treatment for water saving irrigation and ecological management of paddy fields landscape.     

Deficit Irrigation Management of Maize in the High Plains Aquifer Region: A Review

Irrigated agriculture is a major economic contributor of the High Plains Region and it primarily relies on the High Plains Aquifer as a source of water. Over time, areas of the High Plains Aquifer have experienced drawdowns limiting its ability to supply sufficient water to sustain fully irrigated crop production. This among other reasons, including variable climatic factors and differences in state water policy, has resulted in some areas adopting and practicing deficit irrigation management. Considerable research has been conducted across the High Plains Aquifer region to identify locally appropriate deficit irrigation strategies. This review summarizes and discusses research conducted in Nebraska, Colorado, Kansas, and Texas, as well as highlights areas for future research. Editor's note : This paper is part of the featured series on Optimizing Ogallala Aquifer Water Use to Sustain Food Systems. See the February 2019 issue for the introduction and background to the series.     

ENERGY AND WATER CONSERVATION STRATEGIES IN IRRIGATED AGRICULTURE1

ABSTRACT: Growers in California used several energy and water conservation strategies in response to the drought conditions of 1976 and 1977. The strategies included an increased use of ground water, in creased irrigation efficiencies, and shifts in cropping patterns. Drought-related losses to irrigated agriculture were minimized as a result of these modifications. Some future problems may have been created, however, by obtaining the needed water supplies for 1976–77. These problems include the effects of extensive water pumping on ground water reservoirs and ground subsidence. In addition, reduced water application by less frequent irrigation and changes in irrigation methods may affect the total salt balance for future years. Several conservation strategies that have some potential application in California were identified as: maintaining and augmenting surface water supply, increasing power use efficiencies, and improving irrigation efficiencies. Electricity savings associated with water conservation have been estimated as high as 25 percent. Specific near term actions suggested for facilitating conservation included: an expanded irrigation management system, efficient water deliveries, and a continued effort on the part of the individual growers to use resources during periods of normal rainfall as they were used under drought conditions.     

WATER PROBLEMS IN THE INDUS FOOD MACHINE1

ABSTRACT: Examples are drawn from the Indus Basin to explain why on-farm water management problems restrict the output of agricultural products in many LDC's. Data is presented to illustrate the low level of water management knowledge of both the farmers and the current extension agents. Examples of the level of corruption and its effect on the operating system are illustrated. Several requirements that must be met before a large-scale irrigation scheme will actually increase the welfare of LDC's farmers are presented.     

MONITORING OPERATIONS PERFORMANCE IN LARGE-SCALE PUBLIC IRRIGATION SYSTEMS IN INDONESIA1

ABSTRACT: Different allocation and delivery performance ratios are used to assess operations performance in a large scale public irrigation system in Indonesia. Results from this analysis indicate that field management practices deviate substantially from the official operating procedures. The lack of application of a single, standardized procedure for planning water allocations represents a serious constraint to effective monitoring and evaluating system performance. Underestimated and unrealistic planned allocations becomes the justification for overdiversion of water, and has the effect of undermining the resolve of managers to see to it that actual flows meet planned flows. Miscalculating planned allocations, poor matches between planned flows and actual deliveries, overdiversion and misreporting have economic consequences as well. For example, strict adherence to the standard operating rule during the second dry season of 1987 would have resulted in 19,070,000 m³ less water diverted into the irrigation system from the Brantas River or, at a conservative estimate of $1.78 per 100 m³ water, a savings of $339,500. Scope exists for making improvements in management by closer adherence to the standard delivery rule, which will also facilitate proper monitoring and evaluation.