Effet de l'application d'engrais minéral complet NPK et de biochar sur les performances de la culture pure du manioc et de l'association manioc - maïs dans les conditions du plateau des Batéké en République Démocratique du Congo (RDC)

Soil Characteristics Under Savanna and Natural Forest on the Bateke Plateau in the Democratic Republic of Congo. In order to develop a sustainable farming system adapted to the conditions of the Batéké plateau, a preliminary trial was conducted between January 2012 and March 2013 at the Ibi agro-forestry domain after a fallow of 10 years (the last three years without destruction of the vegetation by bush fires) in sandy soil according to a randomized complete block design with four replications. Five treatments were compared: the cassava sole cropping (Maribuata variety) with and without application of 40 kg N, 40 kg P2O5 and 40 kg K2O ha-1, cassava and maize (Samaru variety) intercropping with and without application of 40 kg N, 40 kg P2O5 and 40 kg K2O ha-1, and cassava and maize intercropping with application of 40 kg N, 40 kg P2O5, 40 kg K2O ha-1 and 15 t ha-1 of biochar. The results show that in the edaphic and climatic conditions of the test, the simultaneous installation of cassava and maize at the start of short rains provides a gross added value significantly higher than that of cassava sole cropping. The application of mineral fertilizers hardly improves the gross value added for cassava sole cropping while they however benefits to maize when it is associated with cassava in absence of biochar application. The combined application of mineral fertilizer and biochar make it possible to almost double cassava yield and triple the one of maize compared to the no-input control. Gross profit generated by the combination of cassava and maize with mineral fertilizers and biochar application is about twice higher than what is obtained for the control. The combined application of biochar and mineral fertilizer resulted in a significant increase in pH. This should have been accompanied by improved availability of Phosphorus, Calcium and Magnesium in the soil.