Summary: | An experiment was undertaken to determine the effect of tillage and fertilizer on silage and grain corn production and on soil properties as well as to develop a crop yield model. Conventional, reduced, and zero tillage treatments in combination with inorganic or organic (cattle dairy manure) fertilizer treatments were applied yearly on a clay and a sandy loam soil from 1982 to 1986. The best yields were obtained for the combination of zero or reduced-till and inorganic fertilizers. Zero-till resulted in increased soil density and soil water content and a slight accumulation of P and K in the surface layer of the clay soil. Manure improved soil physical properties especially when combined with zero-till, but resulted in lower N availability to the plants. The factors that limited plant yield in the clay site were plant population, soil nitrate content, bulk density and soil water content. Plant population was the only limiting factor in the sandy loam site. A simplified method for predicting corn yields under different management practices was developed.
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