Abstract
This study investigated the effect of animal manures from cattle, chicken, and horse; plant maures of sawdust, bagasse, grass, coconut coir, and coffee and rice hulls; and inorganic fertilizer, on soil physical and chemical properties and sweetpotato [lpomoea batatas (L.)] yields. Results showed that cv. A28/7 produced a significantly higher tuber yield (254 g plant-1) than cv. 049 (211 g plant-1) but there were no significant differences between cultivars in response to soil amendments. Animal manures, coffee and rice hulls, and inorganic fertilizer significantly increased tuber dry matter yields (241-442 g plant-1) compared to plant manures (35-240 g plant-1). Bulk density was improved with the addition of both animal and plant manures and coffee hull but not with rice hull or inorganic fertilizer. Incorporation of residues with high C:N ratios resulted in reduced yields. Bagasse showed markedly reduced plant growth with chlorotic leaves. These results suggest that animal manures and coffee hulls can improve soil physical and chemical properties and can have beneficial effects on sweetpotato tuber yields.
