COMPARATIVE GROWTH AND YIELD RESPONSES OF RAPE (BRASSICA NAPUS L) TO DIFFERENT SOIL FERTILITY MANAGEMENT AMENDMENTS.

Poor soil fertility contributes to low vegetable yields under resource-poor smallholder farming conditions. Growers usually rely solely on organic soil amendments. This study compared growth and yield responses of B. napus to the recommended treatment and farmersʹ practices. A Completely Randomized Block Design with four treatments replicated three times was used. The treatments comprised poultry manure and inorganic fertilizers (RC); A. polyacantha green leaf manure (A. polyacantha); mixture of decomposing miombo leaf litter and soil (miombo) and the control. Fresh mass yield of B. napus harvested from the whole plot was measured three weeks after transplanting at ten-day intervals. Numbers of shoots and leaves per plant were counted prior to harvesting. Data was subjected to analysis of variance using SPSS for Windows (2003) Version 15.0. Fresh mass yield results were as follows: RC > A. polyacantha > control = miombo at p=0.05. Generally yield levels did not vary (p>0.05) with harvesting time. Treatments showed variation (p<0.05) in the number of shoots and leaves. It was concluded that use of biomass alone at current farmersʹ practices led to lower growth and yield responses of B. napus hence its application should be based on the N of P equivalent at agronomic rates.