Abstract
Precision irrigation optimizes the spatiotemporal application of water using evapotranspiration (ET) maps to assess water stress or soil apparent electrical conductivity (ECa) maps as a proxy for plant available water content. However, ET and ECa maps are rarely used together. We developed high-resolution ET and ECa maps for six irrigated fields in the Midwest United States between 2014–2016. Our research goals were to (1) validate ET maps developed using the High-Resolution Mapping of EvapoTranspiration (HRMET) model and aerial imagery via comparison with ground observations in potato, sweet corn, and pea agroecosystems; (2) characterize relationships between ET and ECa; and (3) identify potential precision irrigation benefits across rotations. We demonstrated the synergy of combined ET and ECa mapping for evaluating whether intrafield differences in ECa correspond to actual water use for different crop rotations. We found that ET and ECa have stronger relationships in sweet corn and potato rotations than field corn. Thus, sweet corn and potato crops may benefit more from precision irrigation than field corn, even when grown rotationally on the same field. We recommend that future research consider crop rotation, intrafield soil variability, and existing irrigation practices together when determining potential water use, savings, and yield gains from precision irrigation.
Highlights
Precision irrigation is an agricultural practice where irrigators optimize the spatiotemporal application of water to maximize yield and minimize environmental impacts, and can reduce water use by up to 50% compared to traditional irrigation systems [1,2]
Potential Precision Irrigation Benefits Depend on Crop Rotation
Our findings suggest that precision irrigation benefits will be crop-specific, even on the same agricultural field
Summary
Precision irrigation is an agricultural practice where irrigators optimize the spatiotemporal application of water to maximize yield and minimize environmental impacts, and can reduce water use by up to 50% compared to traditional irrigation systems [1,2]. Proximal surveys of ECa are conducted prior to tilling, planting, and fertilization on recently drained soils near field capacity [6,7,8]. Under these survey conditions, ECa has been demonstrated to predict soil hydraulic properties (e.g., field capacity, plant available water content) and expose water-limited yield gaps on a variety of soil types around the world [4,9,10,11,12,13,14,15]. To manage water more effectively, irrigators require information on crop water use dynamics throughout the growing season
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