Improving Irrigation Efficiency Research Articles

Irrigation Efficiency Improvement for Sustainable Agriculture in Changing Climate: A Transboundary Watershed Between Iraq and Iran

Efficient water allocation for sustainable irrigated agriculture has become a growing concern, especially in transboundary river basins where the competition between upstream and downstream countries is substantially increasing. In this paper, the Diyala basin, one of the most water-stressed basins shared between Iraq and Iran, was used as an example case study. The water-stress situation is projected to get worse in the foreseeable future, as climate change adversely altered runoff at a time when demand for water is witnessing remarkable growth. Irrigated agriculture is the greatest consumer of the water supply, having a critical role for the efficiency of water use. The study aims at examining the sensitivity of irrigation demands to a set of potential improvements in irrigation efficiency (between 40 % and 60 %) in the riparian countries under different operational conditions. The investigation of the climate trends discloses that the area tends to be drier, with lower precipitation and higher rates of potential evapotranspiration. The possible impacts of climate change on water availability were examined through the simulation of various climatic scenarios with a rainfall-runoff model. Results show that the annual runoff may be reduced from 14 % to 30 %. It is estimated that such reduction can cause considerable water deficits, especially when there are small improvements in irrigation efficiency. This approach can support the development of a set of plausible scenarios to reduce irrigation water demand while maintaining a healthy agricultural sector.

Managing CO2 emission from groundwater pumping for irrigating major crops in trans indo-gangetic plains of India

Groundwater irrigation and energy played an important role in increasing agricultural production and food security in India; however, declining groundwater levels result in an increase of energy consumption and CO2 emission for lifting water. This, in the future, is expected to influence groundwater development and usage policy in India. This study was undertaken to assess the CO2 emission from groundwater irrigation in an agriculturally dominant district, Karnal of Haryana in India, and to explore the possibility of reducing CO2 emission through various management alternatives. This study indicates that the CO2 emission from groundwater irrigation for baseline scenario is the highest for sugarcane (93 kgCO2/ha/m) followed by rice (40 kgCO2/ha/m), wheat (28 kgCO2/ha/m), mustard (26 kgCO2/ha/m), pigeon pea (14 kgCO2/ha/m) and pearl millet (4 kgCO2/ha/m). However, on a district level, the total CO2 emission under the baseline scenario is highest for rice (140,655 Mt) followed by wheat (98,153 Mt) and sugarcane (18,416 Mt). Higher CO2 emissions from rice and wheat are due to more area under these crops. Results also indicate that CO2 emission can be reduced by 32 % by improving pump efficiency from 34.7 to 51 %. Results show that by improving irrigation efficiency in rice by 15 % and in other crops by 20 % over the baseline efficiency, CO2 emissions can be reduced by 23 % in rice and 25 % in other crops. By improving the pump set and irrigation efficiencies together up to the achievable level, CO2 emissions can be reduced up to 48 % for rice and other crops.

Integrated crop water management might sustainably halve the global food gap

As planetary boundaries are rapidly being approached, humanity has little room for additional expansion and conventional intensification of agriculture, while a growing world population further spreads the food gap. Ample evidence exists that improved on-farm water management can close water-related yield gaps to a considerable degree, but its global significance remains unclear. In this modeling study we investigate systematically to what extent integrated crop water management might contribute to closing the global food gap, constrained by the assumption that pressure on water resources and land does not increase. Using a process-based bio-/agrosphere model, we simulate the yield-increasing potential of elevated irrigation water productivity (including irrigation expansion with thus saved water) and optimized use of in situ precipitation water (alleviated soil evaporation, enhanced infiltration, water harvesting for supplemental irrigation) under current and projected future climate (from 20 climate models, with and without beneficial CO2 effects). Results show that irrigation efficiency improvements can save substantial amounts of water in many river basins (globally 48% of non-productive water consumption in an ‘ambitious’ scenario), and if rerouted to irrigate neighboring rainfed systems, can boost kcal production significantly (26% global increase). Low-tech solutions for small-scale farmers on water-limited croplands show the potential to increase rainfed yields to a similar extent. In combination, the ambitious yet achievable integrated water management strategies explored in this study could increase global production by 41% and close the water-related yield gap by 62%. Unabated climate change will have adverse effects on crop yields in many regions, but improvements in water management as analyzed here can buffer such effects to a significant degree.

Improvement of Continuous Deficit Irrigation Efficiency on Young Plum Tree Using Arbuscular Mycorrhizal Fungi

Improvement of Continuous Deficit Irrigation Efficiency on Young Plum Tree Using Arbuscular Mycorrhizal Fungi

Documenting Trends in Water Use and Conservation Practices on U.S. Golf Courses

Since an initial survey was conducted in 2006, U.S. golf courses have reduced their water use by 21.8%, from a projected 2.379 million acre‐feet/year to 1.859 million acre‐feet of water per year. Factors contributing to this decrease include voluntary reductions in number of irrigated acres, reductions in number of golf facilities, and water conservation practices. These practices allowed U.S. golf courses to use less water than predicted by reference evapotranspiration (ETo) values. There is dramatic regional variation in water use patterns across the United States. The median amount of water used by an 18‐hole golf course was highest in the Southwest (3.87 acre‐feet/acre per year) and lowest in the Transition zone (cool‐ to warm‐season grass adaption areas) (0.60 acre‐feet/acre per year), and water use ranged from no irrigation to >9 acre‐feet/acre per year on a course‐by‐course basis. Regional variation was most heavily influenced by climate, due to the broad range of ETo and precipitation values among the study's seven agronomic regions. Recycled water use has increased to approximately 25% of all water used on golf courses in 2013, from 14.7% in 2005. Future decreases in golf course water use will likely depend on further development of water budgeting and water management plans, adoption of monitoring technology, improved irrigation efficiency, and further reductions in irrigated acreages.

Evaluation of different soil water potential by field capacity threshold in combination with a triggered irrigation module

Irrigation efficiency improvement requires optimization of its parameters like irrigation scheduling, threshold and amount of water usage. If these parameters are not satisfactorily optimized, negative consequences for the plant-soil system can occur with decreased yield and hence economic viability of the agricultural production. Numerical modelling represents an efficient, i.e. simple and fast method for optimizing and testing different irrigation scenarios. In this study HYDRUS-1D model assuming single- and dual-porosity systems was used to evaluate a triggered irrigation module for irrigation scheduling in maize/soybean cropping trials. Irrigation treatment consisted of two irrigation regimes (A2 = 60-100% field capacity (FC) and A3 = 80-100% FC) and control plot (A1) without irrigation. The model showed a very good fit to the measured data with satisfactory model efficiency values of 0.77, 0.69, and 0.93 (single-porosity model) and 0.84, 0.67, and 0.92 (dual-porosity model) for A1, A2, and A3 plots, respectively. The single-porosity model gave a slightly better fit in the irrigated plots while the dual-porosity model gave better performance in the control plot. This inconsistency between the two approaches is due to the manual irrigation triggering and uncertainty in field data timing collection. Using the triggered irrigation module provided more irrigation events during maize and soybean crop rotation and consequently increased cumulative amounts of irrigated water. However, that increase resulted in more water available in the root zone during high evapotranspiration period. The HYDRUS code can be used to optimize irrigation threshold values further by assuming different scenarios (e.g. different irrigation threshold or scheduling) or a different crop.

Response of Maize Growth and Yield to Different Water and Nitrogen Schemes on Very Coarse Sandy Loam Soil Under Sprinkler Irrigation in the Semi‐Arid Region of China

AbstractFarmers are being encouraged to shift from conventional surface irrigation to sprinkler irrigation in the semi‐arid region where coarse‐textured soil is predominant in order to improve irrigation efficiency, but their irrigation and fertilization are currently scheduled by the traditional methods obtained from surface irrigation due to insufficient knowledge of the relatively new technology of sprinkler irrigation. This often results in an inefficient use of water and nutrients and a decreased crop yield. The objective of this paper was to quantify the response of maize growth, nitrogen uptake, yield, yield components, water productivity and nitrogen agronomic efficiency to different irrigation and nitrogen application rates under semi‐arid conditions and to determine an optimal irrigation and nitrogen regime for sprinkler irrigation. Field experiments were conducted on a very coarse sandy soil irrigated by a lateral move sprinkler system in the Inner Mongolia Autonomous Region in 2012 and 2013. Three irrigation levels of 40, 70 and 100% of evapotranspiration (ETc) and four nitrogen application rates of 80, 160, 240 and 320 kg ha‐1 were tested in 2012. Whereas in 2013, four irrigation levels of 40, 70, 100 and 130% of ETc and four nitrogen application rates similar to the 2012 experiments were used. For the very coarse soil tested, the irrigation level demonstrated a substantially more important influence on plant growth than nitrogen application rate. A higher irrigation level produced a significantly greater plant height, leaf area index (LAI), dry matter above ground, plant nitrogen uptake, yield and nitrogen agronomic efficiencies (NAE) when irrigation level was between 40 and 100% ETc. However, when the irrigation level exceeded 100% ETc, a reduced yield and NAE was observed. In 2012, the nitrogen application rate of 160 kg ha‐1 usually gave a slightly higher yield and irrigation water productivity (IWP). Whereas in 2013, the nitrogen application rate of 240 kg ha‐1 resulted in the greatest yield and IWP. No significant difference in yield, IWP and NAE was observed between the treatments with nitrogen application rates of 160 and 240 kg ha‐1 for both 2012 and 2013 experiments. A management practice of irrigation at 100% ETc, along with nitrogen application rate of 160 kg ha‐1, was therefore recommended. Copyright © 2015 John Wiley & Sons, Ltd.

Irrigation Control for Improving Irrigation Efficiency in Coir Substrate Hydroponic System

The objectives of this study were to determine optimal length of off-time between irrigation cycles to improve irrigation efficiency using a frequency domain reflectometry (FDR) sensor-automated irrigation (FAI) system for tomato (Solanum lycopersicum L.) cultivation aimed at minimizing effluent from coir substrate hydroponics. For treatments, the 5-minute off-time length between 3-minute run-times (defined as 3R5F), 10-minute off-time length between 3-minute run-times (defined as 3R10F), or 15-minute off-time length between 5-minute run-times (defined as 5R15F) were set. During the 3-minute or 5-minute run-time, a 60mL or 80mL of nutrient solution was irrigated to each plant, respectively. Until 62 days after transplant (DAT) during the autumn to winter cultivation, daily irrigation volume was in the order of 3R5F (858mL) ＞ 5R15F (409mL) ＞ 3R10F (306mL) treatment, and daily drainage ratio was in the order of 3R5F (44%) ＞ 5R15F (23%) ＞ 3R10F (14%). Between 63 and 102 DAT, daily irrigated volume was in the order of 5R15F (888mL) ＞ 3R5F (695mL) ＞ 3R10F (524mL) with the highest drainage ratio, 19% (±2.6), at the 5R15F treatment. During the spring to summer cultivation, daily irrigation volume and drainage ratio per plant was higher in the 3R5F treatment than that of the 3R10F treatment. For both cultivations, a higher water use efficiency (WUE) was observed under the 3R10F treatment. Integrated all the data suggest that the optimal off-time length is 10 minutes.

Optimizing irrigation efficiency improvements in the Aral Sea Basin

Water scarcity driven by climate change, growing demand, and inefficient management of water and related infrastructure is a serious threat to livelihoods in the Aral Sea Basin (ASB) of Central Asia. In recent decades, downstream water shortages have become increasingly common and inflows into the Aral Sea have become very limited. Meanwhile, water losses are enormous both at conveyance and field levels because of outdated infrastructure and the dominance of highly inefficient basin and furrow irrigation methods. Intensification and modernization of irrigation systems, while requiring investment of scarce capital resources, could thus substantially reduce non-beneficial water consumption and help in coping with increasing water scarcity. This study applies a hydro-economic model that solves for the investment in improved irrigation efficiency across the various irrigation sites in the ASB that delivers the highest economic gains. Improvement of the efficiency of irrigation canals and implementation of field efficiency investments and practices, such as drip irrigation, and alternate dry or short furrow irrigation (for rice), would substantially improve economic outcomes. Conveyance efficiency investments are particularly worthwhile in downstream regions where sandy soils are common and return flows largely feed saline lakes in tail-end depressions. Meanwhile, field-level efficiency should be fully upgraded in all rice-producing regions through the use of drip and alternate wet and dry irrigation, as well as with drip irrigation in the cotton-producing Ferghana Valley of the Syr Darya Basin. The value of these improvements increases with reduced water availability. Implementation of an optimal set of investments could increase basinwide benefits by 20% (from US$ 3.2 to 3.8 billion) under normal water availability and by 40% (from US$ 2.5 to 3.5 billion) under dry conditions (80% of normal supply).

Expert knowledge based modeling for integrated water resources planning and management in the Zayandehrud River Basin

Summary This study highlights the need for water resource planning and management using expert knowledge to model known extreme hydrologic variability in complex hydrologic systems with lack of data. The Zayandehrud River Basin in Iran is used as an example of complex water system; this study provides a comprehensive description of the basin, including its water demands (municipal, agricultural, industrial and environmental) and water supply resources (rivers, inter-basin water transfer and aquifers). The objective of this study is to evaluate near future conditions of the basin (from Oct./2015 to Sep./2019) considering the current water management policies and climate change conditions, referred as Baseline scenario. A planning model for the Zayandehrud basin was built to evaluate the Baseline scenario, the period of hydrologic analysis is 21 years, (from Oct./1991 to Sep./2011); it was calibrated for 17 years and validated for 4 years using a Historic scenario that considered historic water supply, infrastructure and hydrologic conditions. Because the Zayandehrud model is a planning model and not a hydrologic model (rainfall–runoff model), an Adaptive Network-based Fuzzy Inference System (ANFIS) is used to generate synthetic natural flows considering temperature and precipitation as inputs. This model is an expert knowledge and data based model which has the benefits of Artificial Neural Networks (ANN) and Fuzzy Inference Systems (FIS). Outputs of the ANFIS model were compared to the Historic scenario results and are used in the Baseline scenario. Three metrics are used to evaluate the goodness of fit of the ANFIS model. Water supply results of the Baseline scenario are analyzed using five performance criteria: time-based and volumetric reliability, resilience, vulnerability and maximum deficit. One index, the Water Resources Sustainability Index is used to summarize the performance criteria results and to facilitate comparison among trade-offs. Results for the Baseline scenario show that water demands will be supplied at the cost of depletion of surface and groundwater resource, making this scenario undesirable, unsustainable and with the potential of irreversible negative impact in water sources. Hence, the current water management policy is not viable; there is a need for additional water management policies that reduce water demand through improving irrigation efficiency and reduction of groundwater extraction for sustainable water resources management in the Zayandehrud basin.

Climate change effects on water availability

Climate isan important factor of agricultural productivity. In large parts of Asia, agricultural production is mainly dependent on monsoon rains. Climate change is characterized by alteration in temperature, precipitation and sea level rise. India will suffer severely from potential changes in temperature and precipitation. Adaptation options available to climate changes are: changing varieties/ crop, altering fertilizer rates to maintain rain or fruit quality and be more suited to the prevailing climate, water harvesting, conserve soil moisture and improving irrigation efficiency and use water more effectively.

Integrated Modeling of Water Supply and Demand under Management Options and Climate Change Scenarios in Chifeng City, China

AbstractWater resource management is becoming increasingly challenging in northern China because of the rapid increase in water demand and decline in water supply due to climate change. We provide a case study demonstrating the importance of integrated watershed management in sustaining water resources in Chifeng City, northern China. We examine the consequences of various climate change scenarios and adaptive management options on water supply by integrating the Soil and Water Assessment Tool and Water Evaluation and Planning models. We show how integrated modeling is useful in projecting the likely effects of management options using limited information. Our study indicates that constructing more reservoirs can alleviate the current water shortage and groundwater depletion problems. However, this option is not necessarily the most effective measure to solve water supply problems; instead, improving irrigation efficiency and changing cropping structure may be more effective. Furthermore, measures to increase water supply have limited effects on water availability under a continuous drought and a dry‐and‐warm climate scenario. We conclude that the combined measure of reducing water demand and increasing supply is the most effective and practical solution for the water shortage problems in the study area.

Forage grasses under drought stress in conditions of Poland

Crop performance and yield are the results of genotypic expression as modulated by continuous interaction with the environment. Among the environmental factors, water is one of the most important, which limits the crop production on a global basis. Water resources in the world are steadily diminishing, and in many areas, including Poland, more frequent periods of drought are observed. There are many problems that are specifically related to water scarcity: an extremely dynamic nature of plant water status, relationship to the severity of the effects of water, time stress during ontogeny of plants, and the interaction of water stress with other environmental variables. The paper presents a review of recent literature on the effect of the grasses to drought stress at the level of physiological processes and the possibility of yielding. A better understanding of how long-term growth and yield are affected by water stress should aid in improving irrigation efficiency and practices, in modifying plants for more efficient water use, and in developing effective dry-land agriculture.

An evaluation of the water utilization and grain production of irrigated and rain-fed croplands in China

Irrigation plays a major role in Chinese agricultural production, as China is experiencing water and food scarcity. Assessing water use (WU) and water productivity (WP) will contribute to regional water management and grain production improvement. This paper quantifies the water use and productivity in grain production for 31 Chinese provinces, autonomous regions and municipalities (PAMs) by distinguishing between irrigated and rain-fed farmland. An indicator of marginal productivity of blue water (MWPb) is established and calculated to evaluate irrigation profits. National water use (WUt) for grain cultivation from 1998 to 2010 was approximately 689.04Gm3 (42.26% blue water and 57.74% green water). The productive water proportions for irrigated and total croplands were 65.57% and 76.85%, respectively. Water use compositions from both blue–green and productive–unproductive perspectives changed slightly over time. The water use productivity (WPU) and water consumption productivity (WPC) for integrated grain products of China during the study period were 0.747 and 0.972kg/m3, respectively. The spatial distribution patterns of irrigated WPs (WPUI, WPCI) were consistent with those for total cropland. China has achieved sufficient food supply without increasing water use. The national MWPb was estimated to be 0.673kg/m3, revealing a higher increase in crop yield on irrigated land compared to rain-fed land. The northeast provinces urgently need to improve irrigation efficiency, and the North China Plain PAMs should promote rain-fed crop yield to increase grain production and control water use in the future.

Simulating Groundwater Dynamics Using Feflow‐3D Groundwater Model Under Complex Irrigation and Drainage Network of Dryland Ecosystems of Central Asia

AbstractSurface and groundwater resources are often conjunctively used to cope with water scarcity in irrigated agriculture. Farmers in the dryland ecosystems of central Asia also utilize shallow groundwater in addition to surface water withdrawn from rivers. This study modelled groundwater dynamics in an irrigation and drainage network in Khorezm region, Uzbekistan. The system, characterized by a vast, unlined channel network used to convey water mainly for flood irrigation and an open drainage system, is typical of Central Asian irrigated areas. Groundwater levels in the region are shallow—this contributes to crop water requirements but threatens crop production through secondary salinization. High losses during irrigation in fields and through the irrigation network are the main causes of these shallow groundwater levels. The main objective of this study was thus to simulate groundwater levels under improved irrigation efficiency scenarios. The FEFLOW‐3D model, applied in a case study to the water users’ association (WUA) of Shomakhulum in south‐west Khorezm, was used to quantify the impact of improved irrigation efficiency scenarios on groundwater dynamics. The modelled scenarios were: current irrigation efficiency (S‐A, our baseline), improved conveyance efficiency (S‐B), increased field application efficiency (S‐C), and improved conveyance and application efficiency (S‐D). Recharge rates were separately determined for six hydrological response units (differing in groundwater level and soil type) and introduced into the FEFLOW‐3D model. After successful model calibration (R2 = 0.94) and validation (R2 = 0.93), the simulations showed that improving irrigation efficiency under existing agro‐hydroclimatic conditions would lower groundwater levels from the baseline scenario (S‐A) in August (the peak irrigation period) on average by 12 cm in S‐B, 38 cm in S‐C and 44 cm in S‐D. Any interventions which would improve irrigation efficiency will lower the groundwater levels and hence policy makers should consider them and formulate the policy accordingly. Copyright © 2015 John Wiley & Sons, Ltd.

Soil water content assessment: critical issues concerning the operational application of the triangle method.

Knowledge of soil water content plays a key role in water management efforts to improve irrigation efficiency. Among the indirect estimation methods of soil water content via Earth Observation data is the triangle method, used to analyze optical and thermal features because these are primarily controlled by water content within the near-surface evaporation layer and root zone in bare and vegetated soils. Although the soil-vegetation-atmosphere transfer theory describes the ongoing processes, theoretical models reveal limits for operational use. When applying simplified empirical formulations, meteorological forcing could be replaced with alternative variables when the above-canopy temperature is unknown, to mitigate the effects of calibration inaccuracies or to account for the temporal admittance of the soil. However, if applied over a limited area, a characterization of both dry and wet edges could not be properly achieved; thus, a multi-temporal analysis can be exploited to include outer extremes in soil water content. A diachronic empirical approach introduces the need to assume a constancy of other meteorological forcing variables that control thermal features. Airborne images were acquired on a Sicilian vineyard during most of an entire irrigation period (fruit-set to ripening stages, vintage 2008), during which in situ soil water content was measured to set up the triangle method. Within this framework, we tested the triangle method by employing alternative thermal forcing. The results were inaccurate when air temperature at airborne acquisition was employed. Sonic and aerodynamic air temperatures confirmed and partially explained the limits of simultaneous meteorological forcing, and the use of proxy variables improved model accuracy. The analysis indicates that high spatial resolution does not necessarily imply higher accuracies.

Assessing potential water savings in agriculture on the Hai Basin plain, China

The Hai Basin in China exemplifies problems that are observed in many arid environments: excessive water consumption, depletion of aquifers, and damage to eco-systems. Progressively since the 1970s water resources in Hai Basin have been over-exploited, primarily for irrigation, while the water requirements of other sectors have increased. Water tables are falling and outflows to the sea are sporadic and heavily polluted. Current consumption of water in the basin is estimated to exceed the renewable supply from rainfall by 6.25×109m3yr−1. Traditional approaches—improving irrigation efficiency through structural works and on-farm technologies such as drip and sprinkler—have failed to restore a balance. Researchers have investigated various on-farm techniques to reduce consumption, including mulching, zero tillage, deficit irrigation, revised cropping patterns, and improved cultivars. We project the results of such experiments for winter wheat (Triticum aestivum L.), maize (Zea mays L.), and cotton (Gossypium spp.) to basin scale to assess their potential in restoring sustainable water consumption. Widespread adoption of mulching, which is the most promising option for farmers, would reduce the over-consumption by 25% (1.6×109m3yr−1). If water quotas are introduced, forcing a reduction in consumption, current production could be maintained while saving 4.1×109m3yr−1. Ending the remaining over-consumption of 2.15×109m3yr−1 would require reducing grain production by 4–7.8Mtyr−1.

Agricultural adaptation strategies to climate change impacts in Africa: a review

Climate change is expected to intensify existing problems and create new combinations of risks, particularly in Africa. The situation is made worst due to factor such as widespread poverty, over dependence on rain fed agriculture, inequitable land distribution, limited access to capital and technology, inadequate public infrastructure, such as roads, long term weather forecasts and inadequate research and extension. By lessening the severity of key damages to the agricultural sector, adaptation is the key defensive measure. Adaptation to climate change involves changes in agricultural management practices in response to changes in climate conditions. This paper reviews agricultural adaptation strategies employed by farmers in various countries in Africa in cushioning the effects of climate change. The common agricultural adaptation strategies used by farmers were the use of drought resistant varieties of crops, crop diversification, changes in cropping pattern and calendar of planting, conserving soil moisture through appropriate tillage methods, improving irrigation efficiency, and afforestation and agro-forestry. The paper concluded that improving and strengthening human capital through education, outreach programmes, extension services at all levels will improve capacity to adapt to climate change impact. DOI: http://dx.doi.org/10.3329/bjar.v39i3.21984 Bangladesh J. Agril. Res. 39(3): 407-418, September 2014

Is irrigation water price an effective leverage for water management? An empirical study in the middle reaches of the Heihe River basin

Serious water scarcity, low water-use efficiency, and over-exploitation of underground water have hindered socio-economic development and led to environmental degradation in the Heihe River basin, northwestern China. Price leveraging is an important tool in water demand management, and it is considered to be effective in promoting water conservation and improving water use efficiency on the premise that water demand is elastic. In the present study, we examine whether price is an effective and applicable instrument for restraining the increasing demand for agricultural irrigation water in the middle reaches of the Heihe River basin and how will it affect farmers’ decisions on irrigation and crop structure. Specifically, the price elasticity of agricultural water demand was estimated based on the irrigation water demand function. The results show that the agricultural irrigation water price is statistically significant, but its elasticity is very low under current low water price. Price leverage cannot play a significant role in the context of the current pricing regime and farmers’ response to price increase is intrinsically weak. To create incentives for conserving water and improving irrigation efficiency, price mechanism should be accompanied with clearly defined and legally enforceable water rights, restricted water quota measures, and reform of water authorities and water-user associations. Furthermore, increases of surface irrigation water price may lead to the over-withdrawal of groundwater, consequently, effective groundwater licensing and levying must take place to limit the total volume of groundwater withdrawal. In all, improving irrigation efficiency through better management and the adoption of water-saving technologies is the ultimate way to deal with the challenges facing irrigated agriculture in the middle reaches of the Heihe River basin.

Grower demand for sensor-controlled irrigation

Water scarcity is likely to increase in the coming years, making improvements in irrigation efficiency increasingly important. An emerging technology that promises to increase irrigation efficiency substantially is a wireless irrigation sensor network that uploads sensor data into irrigation management software, creating an integrated system that allows real-time monitoring and control of moisture status that has been shown in experimental settings to reduce irrigation costs, lower plant loss rates, shorten production times, decrease pesticide application, and increase yield, quality, and profit. We use an original survey to investigate likely initial acceptance, ceiling adoption rates, and profitability of this new sensor network technology in the nursery and greenhouse industry. We find that adoption rates for a base system and demand for expansion components are decreasing in price, as expected. The price elasticity of the probability of adoption suggests that sensor networks are likely to diffuse at a rate somewhat greater than that of drip irrigation. Adoption rates for a base system and demand for expansion components are increasing in specialization in ornamental production: growers earning greater shares of revenue from greenhouse and nursery operations are willing to pay more for a base system and are willing to purchase larger numbers of expansion components at any given price. We estimate that growers who are willing to purchase a sensor network expect investment in this technology to generate significant profit, consistent with findings from experimental studies.