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ARS Home » Midwest Area » Columbia, Missouri » Cropping Systems and Water Quality Research » Research » Publications at this Location » Publication #91870

Title: SOIL ELECTRICAL CONDUCTIVITY AS A CLAYPAN-SOIL CROP PRODUCTIVITY INDEX

Author
item Kitchen, Newell
item Sudduth, Kenneth - Ken
item DRUMMOND, SCOTT

Submitted to: Geospatial Information in Agriculture and Forestry International Conference
Publication Type: Abstract Only
Publication Acceptance Date: 6/2/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Electromagnetic induction methods were used to map claypan soil (Udollic Ochraqualfs) electrical conductivity (EC) variations, and the relationship of these spatial EC measurements to crop production variations was evaluated on four Missouri claypan fields. Soil EC was measured using a Geonics EM38 sensor, while grain yield was measured with a commercial yield dmonitor. Linear correlation coefficients between yield and soil propertie (including EC) were generally low and were inconsistent across years and across fields. The nonlinear relationship between yield and EC was quantified using a "boundary line" established at the upper edge of the yield versus EC scatter plot obtained for each field-year. This boundary was assumed to represent the response of yield to EC when the yield limiting effects of other factors were minimal. Soil EC was strongly correlated to soil depth above the claypan, which in turn could be related to the amount of soil water available for crop production. Within a singl field in any given year, soil water available for crop production may be deficient, optimal, or excessive or may exhibit a combination of these conditions. The log-normal peak function was chosen to represent the boundary line because of its flexibility in fitting any combination of these three conditions. This function approximated the upper boundary particularly well (r**2 > 0.5) in 5 out of 13 field-years. During wet years, EC variations helped explain yield decreases due to both excessive (higher EC) and deficient (lower EC) soil water conditions. During dry years, soil water was generally deficient and yield increased with decreasing EC.