The CocoaSoils nutrient offtake model: preliminary results from on-farm trials

Surprisingly little is known about the nutrient requirements and appropriate mineral nutrition of cocoa. In this paper we describe a cocoa offtake model, which was designed as part of the CocoaSoils project in order to calculate cocoa nutrient requirements based on nutrient offtake rates combined with expert opinions. In addition, we present preliminary results from 150 CocoaSoils Satellite Trials, in which the yield and profitability of nutrient recommendations derived from the offtake model are compared with national recommendations and with farmer practices (no nutrient applications). The offtake model estimates substantial requirements for N (60 kg ha−1 yr−1) and quantities of P and K that are two-three times higher than national recommendations. Preliminary yield results from the Satellite Trials show that fertiliser application increases yields in all countries but Nigeria, but variations between farms and countries are very large. Average yields across farms and treatments are around 1000 kg in Cameroon, 1300 in Côte d'Ivoire, 1200 in Ghana, and 600 kg in Nigeria. The offtake model recommendations lead to significantly improved yields compared with national recommendations in Côte d'Ivoire and Cameroon, but not in Ghana and Nigeria. The return on investment is positive in Ghana and Côte d'Ivoire, but these results are strongly dependent on cocoa and fertilizer prices. Our preliminary analysis show that the offtake model may be a useful too for estimating nutrient recommendations, and that improved fertilizer blends for cocoa farmers could be useful to improve productivity and profitability of cocoa farms in West Africa. 

Keywords: Theobroma cacao L. West Africa, fertilizer, yield, return on investment