Abstract

A pot experiment was conducted to investigate the effect of soil fertility on the establishment of two improved grasses (Pennisetum purpureum and Cynodon nlemfluensis) and two legumes (Desmodium uncinatum andNeonotonia wightii) in soils collected from different fallow periods [0 to 2, 3 to 5, 6 to 10, 11 to 20 years and uncultivated field (control)] in Chivi district in south central Zimbabwe. Five soil samples per fallow period were characterized for soil fertility in terms of mineral Nitrogen (N), Potassium (K), Phosphorus (P), Calcium (Ca), Magnesium (Mg), Sodium (Na), pH and soil texture. A four by five factorial design replicated three times was used to assess the establishment of legumes as measured by percent emergence of legume seeds and grass species as measured by survivability of the grass cuttings at 4 weeks. The data was analyzed using a general linear model (GLM). Overall soil fertility was low. There was no significant difference (P > 0.05) across all the fallow periods. The rate of establishment of the grasses and legumes was not significantly different (P > 0.05) across fallow periods. There were, however, significant differences between species (P < 0.05). A 100% establishment was recorded for grasses, and 67.33 and 50.33% for D uncinatum and N wightii, respectively. The good establishment potential of both improved grasses and legumes indicated that this could be a viable way of improving the productivity of fallows in Chivi district and in similar areas in Zimbabwe.

Key words: Fallows, soil fertility, improved grasses, legumes, establishment.