Field scale variability of nitrogen and delta 15N in soil and plants
1997
Clay, D.E. | Chang, J. | Clay, S.A. | Ellsbury, M. | Carlson, C.G. | Malo, D.D. | Woodson, D. | DeSutter, T.
Understanding the factors that influence soil and plant nitrogen (N) spatial variability may improve our ability to develop management systems that maximize productivity and minimize environmental hazards. The objective of this study was to determine the field (65 ha) scale spatial variability of N and delta15N in soil and corn (Zea mays). Soil, grain, and stover samples were collected from grids that ranged in size from 30 by 30 m to 60 by 60 m. Plant samples, collected following physiological maturity in 1995, were analyzed for total N and delta15N. Soil samples, collected prior to planting in the spring of 1995 and 1996, were analyzed for inorganic-N, total N, and delta15N. All parameters showed strong spatial relationships. In an undrained portion of the field containing somewhat poorly and poorly drained soils there was a net loss of 95 kg N ha-1, while in an adjacent area that was tile drained there was a net gain of 98 kg N ha-1. Denitrification and N mineralization most likely were responsible for losses and gains, respectively. Differences between the N balances of these areas (193 kg N ha-1) provide a relative measure of the impact of tile drainage on plant N availability and greenhouse gas production in a wet year.
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