Abstract
In a three-year study, cowpea and maize were grown in rotation annually on a heavy clay soil on the coast of Guyana with and without tillage. Cowpea was grown in the milder end-of-year rainy season; maize was grown during the heavier mid-year rainy season. There were no significant differences in crop yields in relation to tillage methods. The indications were that crop yields were more influenced by the prevailing rainfall and consequent soil moisture content than by tillage. Maize performance was adversely affected under no-till by excessive soil moisture. No-tillage increased soil moisture and decreased soil temperature in all the trials. Other soil physical differences were not consistent and tended to disappear soon after intense rainfall. After three years of no-tillage, there were visible changes in soil properties but most of the measured differences in physical and chemical properties were not statistically significant. Of particular importance was the development and persistence of soil cracks and the build-up of organic matter on the surface of no-till soil.
