Effects of Maize-Legume Intercropping in Erosion and Soil Biodiversity

Abstract

Maize production with slash and burning crop residues for land preparation is detrimental to the environment. This research compared maize-legume intercrop systems on their effects on soil and nutrient losses, soil biodiversity with farmer’s practice of maize growing with residue burning in 2 experiments during 2013-2015. The first experiment evaluated soil biodiversity in maize intercropped with 4 legumes, namely, with lablab, rice bean, cowpea and mung bean, and farmer’s practice of slash and burn maize at the Royal Project Pang Da research station, Samoeng district, Chiang Mai province. The second experiment compared soil and N losses in maize-lablab intercrop with the farmer’s practice of slash and burn maize and maize without residue burning in at Santi-Suk district Nan province. The maize-legume intercrops produced significantly higher diversity index (H’), 3-4 times the number of individuals, and many more species of soil macrofauna than farmer’s slash and burn maize. Under slash and burn maize there was a soil loss of 12.4 t/rai in the first year and 8.4 t/rai in the second year of experiment. In the first year growing maize without residue burning and maize-lablab reduced soil loss to the same extent by 57%. In the second year soil loss under maize-lablab was reduced by 87% and maize without burning by 61%. These results exemplify how maize production in the highlands may be made more sustainable by intercropping maize with legumes without residue burning which greatly reduced soil and nutrient losses and encouraged soil biological activities and so enhancing fertility.