Value of bush, grass or legume fallow in Ghana

Abstract

Abstract(1) Field studies compare the effects of different periods of bush or grass fallow and of different species of grass and legume in fallows, on the nutrient status of fallow plots and on the yields of subsequent crops.(2) Bush fallowing for 2 years was better than for 1 year, while a third year gave no advantage in respect of yield, and a 5‐ or 6‐year period gave yields no better than did a continuous cropping system.(3) Among grasses and legumes used as fallow cover crops, elephant grass followed, in order, by Guinea grass and pigeon pea were the most effective.(4) At two southerly stations maize yields were increased after fallow but this was not so in three more northerly stations. The difference may depend on the type of fallow, whether grass or legume, and on the availability of nitrogen in the soil. Andropogon grass fallow did not prove so successful in the nitrogen‐deficient soils of the north as did the elephant or Guinea grass in the rich soils of the southern area of forest. The pigeon pea which is less demanding on soil‐nitrogen than are the grasses gave good results at one of the stations in the Guinea Savannah.(5) The final cut of the grass burnt in situ and the burning of the surface soil affected the nutrient status of the soil, increasing chiefly the P, K and Mg; there was no significant difference between the three grass fallow treatments in this respect.Probably, the residues of grass in the 2‐ and 3‐year fallows incorporated in the soil improved the physical condition of soil, thus contributing to the superiority of these grass fallows over the 1‐year fallow in regard to yields of succeeding crops.