Delineating site-specific management units with proximal sensors

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

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 12/10/2009
Publication Date: 7/15/2010
Citation: Corwin, D.L., Lesch, S.M. 2010. Delineating site-specific management units with proximal sensors. In: Oliver, M. (ed.) Geostatistical applications in precision agriculture. New York, NY. Springer. p. 139-166.

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 book chapter to provide an overview of the work by Corwin and colleagues (Corwin and Lesch, 2003, 2005b; Corwin et al., 2003) describing the method for delineating SSMUs using proximal sensors (i.e., sensors that take measurements from within 2 m of the soil surface), with specific emphasis on the spatial statistics that are a fundamental aspect of the methodology. The approach uses spatial measurements of electrical conductivity to locate where soil samples are to be taken to characterize the variability of soil properties influencing the variation of crop yield within a field. Maps of the SSMUs are created that provide a farmer with the vital information for variable-rate technology (e.g., site-specific fertilizer and irrigation water application).

Technical Abstract: Conventional farming uniformly manages fields with no consideration for spatial variability. This causes reduced productivity, misuse of finite resources (e.g., water and fertilizer), and detriment impacts on the environment. Site-specific management units (SSMUs) 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. Mobile proximal sensors, such as those used to measure apparent soil electrical conductivity (ECa), can be used to characterize the spatial variability of soil properties influencing crop yield. It is the objective of this book chapter 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 based on edaphic and anthropogenic properties, with particular emphasis given to the geostatistical techniques needed to direct soil sampling to spatial characterize variability. The approach uses geospatial ECa measurements to locate where soil samples are to be taken to characterize the variability of soil properties influencing the variation of crop yield. 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 (e.g., site-specific fertilizer and irrigation water application).