Application of Geo-refrenced Geophysical Measurements to Precision Agriculture

Authors: Corwin, Dennis; LESCH, SCOTT - UC RIVERSIDE

Submitted to: Fast Times: News for the Near Surface Geophysical Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/2008
Publication Date: 7/15/2008
Citation: Corwin, D.L., Lesch, S.M. 2008. Application of Geo-refrenced Geophysical Measurements to Precision Agriculture. Fast Times: News for the Near Surface Geophysical Sciences. Vol 13, No.2 29-37

Interpretive Summary: Crop yield varies within fields due to nonuniformity of a number of factors including climate, pests, disease, management, topography, and soil. Conventional farming manages a field uniformly; as a result, conventional farming tends to wastes resources and money, and tends to detrimentally impact the environment. One way of handling crop yield variability in a cost and resource effective manner is divide a field into management units based on the observed yield and soil variability so that each unit can be treated similarly in order to optimize yield, resource utilization, and profitability, and minimize detrimental environmental impacts. These site-specific management units or SSMUs are a key component of precision agriculture. It is the objective of this magazine article to provide an overview of the work by Corwin and colleagues (Corwin and Lesch, 2003, 2005b; Corwin et al., 2003) describing the equipment, methods, and techniques for delineating SSMUs using GPS-referenced apparent soil electrical conductivity (ECa) measurements. The approach uses ECa measurements to locate where soil samples are to be taken to characterize the variability of soil properties influencing the variation of cotton yield within the field. Maps of the SSMUs are created that provide a farmer with the vital information for variable-rate technology (i.e., site-specific fertilizer and irrigation water application).

Technical Abstract: Crop yield varies within a field because conventional farming manages fields uniformly with no consideration for spatial variability. Site-specific management units (SSMUs), a key component of precision agriculture, have been proposed as a means of handling the spatial variability of various factors (i.e., soil, climate, management, pests, etc.) influencing crop yield variation in order to increase crop productivity. It is the objective of this magazine article to provide an overview of the work by Corwin and colleagues (Corwin and Lesch, 2003, 2005b; Corwin et al., 2003) that lead to the delineation of SSMUs. Equipment, methods, and techniques are presented for delineating SSMUs using geo-referenced apparent soil electrical conductivity (ECa) measurements. The approach uses the ECa measurements to locate where soil samples are to be taken to characterize the variability of soil properties influencing the variation of cotton yield within a 32.4-ha field. A crop yield response model is developed and maps of SSMUs are prepared using a geographic information system of the spatial soil and crop yield information. The methodology for delineating SSMUs can be used whenever ECa correlates with yield. The ability to create maps of SSMUs provides the vital information for variable-rate technology (i.e., site-specific irrigation water application).