Cassava Yield and Economic Response to Fertilizer in Tanzania, Kenya and Ghana

2018

English

Cassava (Manihot esculenta Crantz) is a major food crop in Africa with little information of response to applied nutrients. Our objectives were to: determine cassava yield response to macronutrients for production areas in Ghana, Kenya and Tanzania; evaluate the effect Mg, S, Zn and B application; and determine agronomic efficiency (AE) and value cost ratio (VCR) for nutrient application. Fresh storage root yield with no fertilizer averaged 14.4 Mg ha–1 and mean yield increases due to 80 kg ha–1 N applied were 8.1, 6.5 and 9.0 Mg ha–1 in Ghana, Kenya and Tanzania. Storage root yield was increased 93% with P application for Aduma in Ghana and there was a curvilinear to plateau response to K at Wenchi Ghana. No other responses to P and K rates occurred, but an N × P synergism occurred in Tanzania. There were no responses to applied Mg, S, Zn, and B. The VCR for N at all sites was >2 indicating sufficient profit opportunity to make N application attractive to many financially constrained farmers. The mean soil organic C (SOC) was 8 g kg–1; the results may lose applicability with much higher SOC soils. Over all trials, application of 80 kg ha–1 N had, on average 8.44 Mg ha–1 increased yield with 105 kg kg–1 agronomic efficiency and 7.8 $ $–1 profit to cost ratio. The results indicate that cassava is efficient in P and K uptake with restricted and little profit potential for P and K application in these countries, respectively.

Senkoro, C. J.; Tetteh, F. M.; Kibunja, C. N.; Ndungu-Magiroi, K. W.; Quansah, G. W.; Marandu, A. E.; Ley, G. J.; Mwangi, T. J.; Wortmann, C. S.