Maize response to doubled-up legumes, compost manure and inorganic fertiliser on smallholder farms in Ntcheu district of Malawi

摘要

A study was carried out in 2011/2012 and 2012/2013 growing seasons in Kandeu and Manjawira Extension Planning Areas (EPAs) in Ntcheu district, Central Malawi, to determine maize response to crop residue incorporation from legume cropping systems and compost manure. In 2011/2012 growing season, maize with or without compost manure, sole and intercropped legumes (pigeon pea, groundnut, soyabean and cowpea) were planted.? In 2012/2013 growing season, maize was planted as a test crop to assess its response to residues from legumes after harvest and N fertiliser. The experiment was laid out in a randomised complete block design, replicated 38 times. Maize grain yields following incorporation of legume crop residues were 1000 kg higher than from continuous sole cropped maize in both Kandeu and Manjawira EPAs, (p <0.001). There was no significant difference in maize grain yield following sole and doubled-up legumes. Grain yield of sole-cropped unfertilised maize, maize with inorganic fertiliser and compost manure were significantly different (p<0.001) across farms in Kandeu EPA, with an average of 3159 kg for fertilised (92 kg N ha-1) maize. Grain yield following sole groundnuts and top dressed with 23 kg N ha-1 was higher (3542 kg) compared to maize fertilised with 92 kg N ha-1 (3159 kg) in Kandeu EPA. Risk assessment showed that maize grain yield from maize following sole cowpea, sole pigeonpea, sole soya bean, pigeonpea intercropped with cowpea and groundnut intercropped, and maize with compost manure was equal to or more than 1300 kg? ha-1 at 25% risk. This grain yield was above that of continuous maize with 92 kg N ha-1, and paused less risk of harvesting maize grain below the recommended grain requirement. This suggest that organic matter addition from various legume cropping system, supplemented with low nitrogen inputs from inorganic fertiliser, offer a viable option for improving maize grain yield rather than depending on inorganic fertiliser alone.