The effects of tillage, mulching and termite control strategies on termite activity and maize yield under conservation agriculture in Mozambique

Abstract

Conservation Agriculture (CA) is a farming system premised on minimum soil disturbance, provision of permanent soil cover and the use of crop rotation/associations. However, in central Mozambique, provision of permanent soil cover is threatened by termites which feed on the residues. This study investigated the effectiveness of tillage and mulch management in CA as well as termite control strategies including local natural indigenous techniques on termite activity, crop lodging and maize (Zea mays L.) yields. The study was carried out at a research site in Chimoio, Central Mozambique over two seasons, 2011/12 and 2012/13. The application of crop residues in CA significantly increased (p < 0.05) termite activity measured through surface area covered by termite galleries (termite activity) from 6.4 to 11.5% and termite numbers per litter bag from 78 to 138 in fields without and with residues, respectively. Residue application also reduced maize crop lodging due to termite attack as the termites preferentially fed on the maize residues. However, tillage effects alone on termite activity were not apparent. Maize yield increased significantly on switching from conventional tillage to minimum soil disturbance (no till) but not with residue application. With respect to the termite control methods tested, only the commercial insecticide fipronil (phenylpyrazole) proved to be effective in reducing termite consumption of residues and also significantly reduced lodging of maize plants at harvest. At least 1.5 t ha−1 of the residues remained in the system where fipronil was applied in comparison to 0.41–0.48 t ha−1 in the other treatments by November 2013. Maize grain yields were negatively correlated (p < 0.05) to crop lodging due to termite damage while crop lodging in turn declined significantly with application of surface residues. Termite activity was however not significantly correlated to crop lodging, suggesting that termite activity could increase without necessarily increasing crop lodging. Thus in cases where termite damage increases to pest proportions, commercial control insecticides such as fipronil, offer a possible solution to control termites but its economic and long term environmental effects need to be evaluated.