Abstract
Agriculture faces the challenge of feeding a growing population with limited or depleting fresh water resources. Advances in irrigation systems and technologies allow site-specific application of irrigation water within the field to improve water use efficiency or reduce water usage for sustainable crop production, especially in arid and semi-arid regions. This paper discusses recent development of variable-rate irrigation (VRI) technologies, data and information for VRI application, and impacts of VRI, including profitability using this technology, with a focus on agronomic factors in precision water management. The development in sprinkler systems enabled irrigation application with greater precision at the scale of individual nozzle control. Further research is required to evaluate VRI prescription maps integrating different soil and crop characteristics in different environments. On-farm trials and whole-field studies are needed to provide support information for practical VRI applications. Future research also needs to address the adjustment of the spatial distribution of prescription zones in response to temporal variability in soil water status and crop growing conditions, which can be evaluated by incorporating remote and proximal sensing data. Comprehensive decision support tools are required to help the user decide where to apply how much irrigation water at different crop growth stages to optimize water use and crop production based on the regional climate conditions and cropping systems.
Highlights
Agriculture is the largest consumer of the world0 s available fresh water, as plant growth largely depends on the availability of water
This study showed that topographic indices, such as distance to flow accumulation lines (DFL), were negatively correlated with yield, could be used to evaluate spatial yield variability
The results showed that the spatial variability due to biological variables was similar in magnitude as compared to that exhibited by physicochemical parameters, which indicated the feasibility of site-specific management of biological variability in the field using management zones
Summary
Agriculture is the largest consumer of the world0 s available fresh water, as plant growth largely depends on the availability of water. Conventional farming practices manage an agricultural field uniformly without incorporating the intrinsic variability in topography, soil, crop growth conditions, and other agronomic factors This can result in nutrient leaching, environmental contamination, and reduced profitability especially when applying high inputs in low yielding areas and vice versa [6,7]. The variable rate technology provides the ability to site- apply irrigation water in the field to achieve potential water savings [18]. This enables the timely and accurate water application incorporating the spatial and temporal soil properties and plant demand at different growth stages [15]. The objective of this paper is to review the scientific background and technologies in precision water management, with the focus on agronomic factors and strategies for site-specific water management
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