Effet du Di-ammonium Phosphate (DAP) sur la valeur fertilisante de la balle de riz (Oryza sativa L.)
Désiré Nimubona et Salvator Kaboneka
The present experimental pot study aimed at évaluating the fertilizer value of rice husks complemented with DAP (18-46-0). Addition of DAP was expected to boost mineralization and nutrient release from rice husks through C/N and C/P ratios reduction. The test crop was maize (Zea mays L.) harvested at the vegetative stage after 1 month after seed sowing. The experimental design was a completely randomized design with 3 replicates and 5 treatments. Rice husks (RH) was applied at an equivalent of 1 T/ha. Treatments under evaluation were: T1=Control, T2=RH+0 kg DAP/ha, T3=RH+27 kg DAP/ha, T4=RH+54 kg DAP/ha, T5=RH+81 kg DAP/ha. Three harvests were performed at 4 weeks interval. At each of the 3 harvests and their combination, an analysis of variance followed by a test of Newman-Keuls were performed on maize plant height, root, shoot and total dry biomss. Although the effect of DAP fertilizer application rates had disappeared at the third harvest, maize growth and biomass production followed the decreased order hereafter: T5 > T4 >T3 T2 >T1, without a clearly expressed proportionality of DAP application rates. In the end, the study indicates that rice husks could directly be used as organic manure provided they are complemented with mineral fertilizers. However, we advise that to be conclusive, our results are be tested under field conditions, with co-composted rice husks with mineral fertilizers or low C/N ratio organic residues.