Characterization of nitrogen dynamics in a pasture soil by electromagnetic induction |
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| Authors: | Liesbet Cockx Marc Van Meirvenne Georges Hofman |
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| Institution: | (1) Department of Soil Management and Soil Care, Ghent University, Coupure 653, 9000 Ghent, Belgium |
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| Abstract: | The aim of this study was to investigate how electromagnetic induction can be used to improve the characterization of N dynamics in a 1.2 ha pasture. The soil apparent electrical conductivity (ECa) was measured by electromagnetic induction using an EM38DD. At 116 locations, soil samples were taken according to a clustered sampling design, three times during one winter, and analyzed for the NO3––N content in the topsoil (0–60 cm). Management zones were delineated using a fuzzy k-means classification of the interpolated ECa measurements. Two ECa zones were found, reflecting mainly differences in soil texture. Since the mean NO3––N content was different for the two ECa zones (24 and 65 kg/ha in November 2002), the residuals were interpolated using stratified simple kriging. This allowed evaluating the NO3– dynamics during the winter in both zones; one ECa zone showed a higher risk for NO3– losses than the other calling for a site-specific N management. As a validation, NO3––N was interpolated using ordinary kriging without stratification. This resulted in similar zones confirming the usefulness of the ECa measurements to assess N-specific management zones, even within small fields. |
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| Keywords: | Electromagnetic induction Geostatistics Management zones Nitrate dynamics |
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