Abstract

In Malawi, increasing human population and low productivity of cassava (Manihot esculenta [Crantz]), the second most important food crop after maize, necessitate the intensification of agronomic options for cassava production. A study was therefore conducted in 2012-2013 season on a chromic Luvisol at Bunda College (14° 35 S’; 33° 50 E’), Central Malawi, to evaluate the effects of inorganic fertilizer (kg ha^-1 N : P₂O₅ : K₂O : S at 0 and 46:42:0:8) and cattle manure (0, 5 and 10 t ha^-1) on cassava growth and yield in a 3 x 2 factorial randomized complete block design replicated four times. The sweet variety Mbundumali with 9-15 months maturity and potential yield of 25 t/ha was used. The study site’s inherent soil chemical characteristics in the 15-30 cm depth were: P = 102 ppm, K = 3.87 meq 100g^-1, N = 0.16%, pH = 5.4, organic matter = 1.79 and N = 0.064. From the results, tuber fresh yield was significantly increased by application of both cattle manure (P = 0.043) and inorganic fertilizer (P = 0.001) while there was no significant manure x inorganic fertilizer interaction. Tuber fresh yield was maximum at 27.6 t/ha with application of cattle manure at 5 t ha^-1, however increasing the rate of cattle manure to 10 tha^-1 did not increase the tuber yield further. Fresh tuber yield increased from 22.8 to 29.2 t ha^-1 with inorganic fertilizer application. Yield without fertility amendments was 21 t ha^-1, suggesting that appropriate amendments may raise yields above potential. There were also significant effects of inorganic fertilizer on branches per plant, tubers per plant and tuber length, while manure had no effect on these variables.

Key words: Cassava, cattle dung, integrated soil fertility management, cassava growth.