Effects of Chromolaena and Tithonia Mulches on Soil Properties, Leaf Nutrient Composition, Growth and Yam Yield

Abstract

Plant materials differ in their chemical composition, rate of decomposition and suitability as mulch materials. Experiments were conducted on an Oxic Tropuldalf of southwestern Nigeria at Owo to study the effect of Chromolaena and Tithonia mulches applied at 0.0, 5.0, 7.5, 10.0 and 12.5 t ha-1 on soil chemical properties, leaf nutrient composition, growth and tuber yield of white yam (Dioscorea rotundata Poir). Both Chromolaena and Tithonia mulches reduced soil bulk density and temperature. They also increased concentrations of organic matter, N, P, K, Ca and Mg in the soil, and N, P, K, Ca and Mg in the leaves. The mulches also increased growth and yield of yam compared with the control. The values of soil organic matter, N and P, and leaf N and P concentrations increased with increasing mulch rate. Chromolaena mulch and Tithonia mulch applied at 10.0 and 7.5 t ha^-1, respectively, were found to be suitable for yam production. Tithonia mulch compared with Chromolaena mulch produced higher values of soil chemical properties, leaf nutrient concentrations, growth and yield of yam. Tithonia mulch produced 19% and 18% higher tuber yield compared with Chromolaena mulch in the first and second cropping seasons, respectively.