Location: Sustainable Water Management ResearchTitle: Development and evaluation of a variable rate irrigation method in Mississippi Delta
Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/25/2020
Publication Date: N/A
Interpretive Summary: Soil properties and crop yield potential can vary considerably within a single field resulting in variability of water required for plant to grow. Variable rate irrigation (VRI) technology can site-specifically apply irrigation water at variable rates within a single field to account for the temporal and spatial variability in soil and plant characteristics. USDA ARS Scientists at Sustainable Water Management Research Unit at Stoneville, MS developed a VRI method and tested the method in Mississippi Delta for 5 crop-years. Results indicated the VRI management significantly reduced amount of irrigation water by 22% in corn and 11% in soybean. Adoption of the VRI management method could improve irrigation water use efficiency in the Mid-South.
Technical Abstract: Variable rate irrigation (VRI) allows the producers to site-specifically apply irrigation water at variable rates within a field to adjust the temporal and spatial variability in soil and plant characteristics. Developing practical VRI methods and documenting the benefits of VRI application are critical to accelerate the adoption of VRI technologies. Using apparent soil electrical conductivity (ECa) and soil moisture sensors, a VRI method was developed and evaluated with corn and soybean for five crop-years in Mississippi Delta. Soil ECa of the study fields was mapped and used to delineate VRI management zones and create VRI prescriptions. Irrigation was scheduled using soil volumetric water content measured by soil moisture sensors. A center pivot VRI system was employed to deliver irrigation water according to the VRI prescription. Grain yield, irrigation water use, and irrigation water productivity in the VRI treatment were determined and compared with that in the uniform rate irrigation (URI) treatment. Results showed that the grain yield and irrigation water productivity between the VRI and URI treatment were not statistically different (p = 0.29) with both corn and soybean crops. The VRI management significantly reduced amount of irrigation water by 22% in corn and 11% in soybean (p = 0.05). Adoption of the VRI management method could improve irrigation water use efficiency in the Mississippi Delta.