Effect of crop rotation on aflatoxin contamination in groundnuts

Aflatoxins are secondary metabolites primarily produced by the fungi Aspergillus flavus, A. parasiticus and, to a lesser extent, A. nomius. Good agricultural practices can aid in the reduction of aflatoxin contaminatio in the field. Well planned crop rotations can reduce A. flavus populations in the soil and hence reduce the risk of aflatoxin develepment in the kernels. The main objective of the study was to assess the effect of crop rotation on aflatoxin contamination in groundnuts. The trial was carried out for two growing seasons from 2014/ 15 to 2015/16 at Chitedze Agricultural Research Station (CARS) in Lilongwe district and Mwimba in Kasungu of Malawi. In both sites, crop rotation treatments were sorghum, maize, sunflower, groundnuts, pegion peas, cotton, finger millet and a fallow. The following crop rotation sequences were effective in reducing aflatoxin contamination in the subsequent crops: fallow (0 ppb) / groundnuts (3.6 ppb), followed by pigeonpea (34.02 ppb)/maize (3.73 ppb), cotton (18.75 ppb)/ groundnuts (7.6 pbb) and finger millet (4.39 pbb)/cotton (3.40 pbb). On the other hand, the following crop rotation sequences increased the contamination of subsequent crops: groundnuts (3.52 pbb)/maize (7.33), maize (2.07 pbb)/groundnuts (19.6 pbb), sorghum (35.75 pbb)/Cotton (40 ppb), and pigeonpea (2.70 pbb)/ pigeonpea(39.73 pbb). The results indicated that selected rotations can be used to reduce aflotoxin contamination.