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Site-Specific Productivity Zones Delineated Using Bulk Soil Electrical Conductivity

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Paper number  032340,  2003 ASAE Annual Meeting . (doi: 10.13031/2013.15322)
Authors:   Newell R. Kitchen, Kenneth A. Sudduth, Brent Myers, Scott T. Drummond, Suk Young Hong
Keywords:   soil electrical conductivity, productivity management; precision agriculture, sensors, EM38, Veris 3100, claypan soil

Efficient and cost-effective methods are needed for delineating sub-field productivity zones to improve soil and crop site-specific management. This investigation was conducted to answer the question of whether bulk soil electrical conductivity (ECa) and elevation could be used to delineate productivity zones (SPZ) for claypan soil fields that would agree with productivity zones delineated from yield map data (YPZ). Ten and seven years of combine-monitored yield maps were available for two Missouri claypan soil fields, designated Field 1 and Field 2, respectively. The fields were generally cropped in corn and soybean. Soil ECa data were collected with a non-contact, electromagnetic induction-based ECa sensor (Geonics EM38) and a coulter-based sensor (Veris 3100). Elevation data was collected using a real-time kinematic GPS. Unsupervised fuzzy c-means clustering was independently used both on yield data to delineate three YPZ and on combinations of ECa and/or elevation data to delineate three SPZ. Outcomes of YPZ and SPZ were matched and agreement calculated with an overall accuracy statistic and a statistical index called the Kappa coefficient. The five SPZ outcomes that gave the highest Kappa coefficient were reported. Best performing combinations of ECa and elevation variables gave 60 to 70% agreement between YPZ and SPZ. We consider this level of agreement promising, especially considering the fact that there were many other yield-limiting factors unrelated to ECa and elevation. Generally multiple variables of ECa and elevation were better than a single variable for generating SPZ. The specific combinations of ECa and/or elevation variables that gave highest agreement between YPZ and SPZ were field specific. Based on these findings, we conclude ECa and elevation measurements could be reliably used for creating productivity zones on claypan soil fields.

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