Combined Inputs of Crop Residues and Fertiliser For Smallholder Maize Production in Southern Malawi

African Crop Science Journal, Vol. 7. No. 4, pp. 365-373, 1999 Combined Inputs of Crop Residues and Fertiliser For Smallholder Maize Production in Southern Malawi Code Number: CS99027 ABSTRACT: Chronic shortage of food exists in Southern Malawi because of low maize (Zea mays L.) yields due, in large part, to soil fertility depletion. An approach to ameliorating soil fertility is strategic use of crop residues and mineral fertilisers. An on-farm experiment was conducted in two contrasting locations, Kasonga (9 farms) and Songani (8 farms) that examined the effects and interactions of applying fertilisers and crop residues to soils. Crop residues consisted of maize stover and soybean (Glycine max (L) Merr.) trash of four cvs. Bossier, Ocepara 4, Kaleya and Magoye that were obtained from a previous crop at each farm. Average organic N inputs ranged between 15 kg N ha-1 for maize stover and 74 kg N ha-1 for soybeans and fertiliser N inputs were 0, 20, 40 and 60 kg N ha-1 with small amounts of accompanying P (0-13 kg P ha-1). ANOVA of maize grain yield revealed significant effects of location (P<0.001), fertiliser addition (P<0.001) and crop residue type (P=0.002). Overall grain yields were much larger at Songani (2374 kg ha-1) than Kasonga (812 kg ha-1). Fertilisation resulted in maize yields ranging between 901 kg ha-1 with no fertiliser to 1955 kg ha-1 with addition of 60 kg N and 13 kg P ha-1. ANOVA of total N uptake by maize revealed highly significant effects of location and fertilisation (P<0.001) and a significant effect of residue type (P=0.02). Overall N uptake by maize was 19.6 kg ha-1 at Kasonga and 62.7 kg ha-1 at Songani. The highest N uptake resulted from maximum fertilisation and with residues of soybean cvs. Bossier and Magoye. Use of fertilisers and soybean residues proved an effective strategy to increase maize yields but further studies that examine the economics of these interventions are necessary. KEYWORDS: Crop rotation, Glycine max, maize stover, nutrient recycling, smallholder farming systems, soil fertility Copyright 1999, African Crop Science Societ