Soil Nitrogen Availability after Long-term Continuous No-tillage and Conventional Tillage Corn Production1
- C. W. Rice,
- M. S. Smith and
- R. L. Blevins2
Several short-term studies of no-tillage (NT) vs. conventional tillage (CT) have suggested that N availability is lower in NT. Less is known about the long-term effects of NT on soil processes and N availability. Recent observations of a NT vs. CT experiment, initiated in 1970 on a Maury silt loam (Typic Paleudalfs), are presented here. During the first 9 yr of this study corn (Zea mays L.) yields with no N fertilizer were consistently greater in CT than NT, but at high N rates yields were approximately equal. Since 1979, there have been no consistent differences between the tillage systems with regard to yield without N or in relative response to N. Inorganic soil N during 1981 and 1982 was usually equal but occasionally greater in NT compared to CT, in contrast to previous observations during the early years of this experiment. Soil N mineralization was estimated in 1982 by a laboratory soil core incubation technique and by observing dilution rates of labeled N added to field microplots. Both of these approaches suggested that N mineralization was at least as great in long-term NT plots as in long-term CT plots. We suggest that the lower availability of N frequently observed in NT soils, in some cases can be a transient effect. In this experiment availability of soil N in NT apparently approached that of CT after approximately 10 yr.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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