Brown manuring optimization in maize: impacts on weeds, crop productivity and profitability

Field experiments were carried out in order to investigate if brown manuring (BM) using Sesbania plants can be used to control weeds in maize, especially Cyperus rotundus (Experiment I), and further to optimize the BM technology through appropriate Sesbania seed rate (S), 2,4-D application time (T) and dose (D) (Experiment II). Each BM treatment received a pre-emergence application of pendimethalin 1.0 kg a.i./ha. Experiment I showed that the BM practice using 15 kg/ha Sesbania seed and 2,4-D 0.50 kg a.i./ha applied at 25 DAS led to better control of weeds, especially C. rotundus and higher maize grain yield. Further optimization studies (Experiment II) indicated that among the factors S, T and D, the BM combination S25 kg/ha, D0.50 kg a.i./ha and T25 DAS (i.e. S25T25D0.50) resulted in lowest weed density (3.1/m(2)) and dry weight (3.8 g/m(2)) and highest weed control index (89.2%) at 60 days after sowing (DAS) which was at par with another BM practice S15T25D0.50. However, the later BM combination led to significantly higher maize productivity (5.25 t/ha) and profitability (net returns (NR) $878/ha), which were 103 and 280% higher, respectively, than the weedy check (WC). The Sesbania seed rate S15 kg/ha gave 7% higher maize grain yield and 12% higher NR than its corresponding level S25 kg/ha. Therefore, Sesbania BM with 15 kg seeds/ha and 2,4-D at 0.50 kg a.i/ha applied at 25 DAS can be recommended for effective and eco-friendly weed management in maize, which would provide higher maize grain yield and enhance farmers' profitability.