Combining Site Specific Data with Geospatial Analysis to Identify Variable Rate Irrigation Opportunities in Irrigated Agricultural Fields.

Abstract. Increasing demand for improving irrigation water use efficiency (IWUE) across irrigated croplands has producers looking for new opportunities to conserve water and maintain their crop production levels. Variable Rate Irrigation (VRI) technology may provide opportunities to enhance IWUE, but as with site-specific crop management of other crop inputs, all fields may not benefit from an approach which utilizes VRI. To consider the potential benefits of VRI, it will be necessary to examine multiple site-specific spatial data layers (e.g., crop yield, soil type/texture, and terrain) as well as the current conditions within a field using geospatial analysis techniques.

The goal of this study was to identify trends and valuable relationships among various spatial data layers collected throughout the growing season to determine if possible management zones can be defined. Location specific studies were conducted in summer of 2013 which resulted in soil classification and crop growing season volumetric water content of the soil profile. The result of this study provided information on the soil electrical conductivity (EC) relationship with soil properties including clay content and organic matter. Full-field data layers analyzed include soil EC, topographic wetness index (TWI), and crop yield to find any correlations that could be used to begin defining management zones throughout the field. For this specific field it has been determined that yield trends are closely related to EC trends. When comparing EC with soil properties the result was a positive relationship with clay content and inverse relationship with organic matter.