ABSTRACT:
Conservation of soil moisture is one of the major advantages of no-till crop production systems. In a long-term tillage study, higher soil moisture under no-till corn production was observed as compared with that under conventional tillage throughout the growing season. Significantly less evaporation occurred under no-till early in the growing season. This conservation of soil water may carry the no-till crop through short drought periods without severe moisture stresses developing in the plants. However, the extra water conserved under no-till can occasionally be detrimental under conditions in which excessive soil water contributes to denitrification losses. Soil compaction in no-tillage soils was not found to be a problem. Saturated hydraulic conductivity measurements suggest better water movement in no-tillage compared with conventional tillage. After 10 years of continuous no-till corn production, no deterioration of soil physical properties was observed. The most obvious chemical change was the rapid acidification of the soil surface when high nitrogen fertilizer rates were used. Associated with reduced soil pH were increased levels of exchangeable aluminum and manganeses. Exchangeahle calcium was sgnificantly lower for no-till at all soil depths and all nitrogen fertilizer rates compared with conventional tillage. Potassium was concentrated in the 0-to-5-centimeter soil layer under no-till and decreased with depth. Exchangeable magnesium in the 0-to-5-centimeter soil depth declined with increased nitrogen fertilizer and was lower in no-till than in conventional tillage. Organic matter was twice as high in the 0-to-5-centimeter soil depth compared with conventional tillage systems. This modified soil environment affects chemical reactions and the distribution and activity of microbes. It also has a significant effect on the fate of surface-applied nitrogen fertilizer. Methods and time of nitrogen fertilizer application may need some modification to reduce possible nitrogen losses by denitrification or temporary immobilization of nitrogen.
Footnotes
R. L. Blevins is a professor, M. S. Smith is an assistant professor, G. W. Thomas is a professor, and W. W. Frye is an associate professor of agronomy at the University of Kentucky, Lexington, 40546. Published as Journal Paper No. 83-3-40, with approval of the Director of the Kentucky Agricultural Experiment Station.
- Copyright 1983 by the Soil and Water Conservation Society
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