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Title: Delineating site-specific management units using geospatial ECa measurements

Author
item Corwin, Dennis
item LESCH, SCOTT - UC RIVERSIDE, CA
item Shouse, Peter
item SOPPE, RICHARD - ALTERRA,WAGINENGEN,NETH
item Ayars, James

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 7/1/2007
Publication Date: 3/1/2008
Citation: Corwin, D.L., Lesch, S.M., Shouse, P.J., Soppe, R., Ayars, J.E. 2008. Delineating site-specific management units using geospatial ECa measurements. In: B.J. Allred, J.J. Daniels and M.R. Ehsani (editors) Handbook of Agricultural Geophysics. CRC Press. Boca Raton, FL. Chapter 16 pp: 247-254.

Interpretive Summary: Crop yield varies within fields due to nonuniformity in a number of factors including climate, pests, disease, management, topography, and soil. Conventional farming manages a field uniformly, so inputs and labor are expended to bring the least productive areas up to an acceptable productivity level. 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 to precision agriculture. It is the objective of this book chapter to present a case study for an irrigated cotton field that describes the equipment, methods, and techniques for delineating SSMUs using GPS-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 the field. Maps of the SSMUs are created that provide 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 book chapter in Handbook of Agricultural Geophysics to present a case study for an irrigated cotton field that describes the equipment, methods, and techniques for delineating SSMUs using GPS-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 the 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 fertilizer and irrigation water application).