Weed seed bank size and composition in an arable crop mulched with pruningfrom three multipurpose trees in southwestern Nigeria

Weed seed bank size and composition were analysed in 1995 and 1996 in maize fields mulched with pruning from Gliricidia sepium, Leucaena leucocephala, and Senna siamea in South Western Nigeria. Plots mulched with pruning from the three trees had a lower weed seed bank in the first year of cropping t han unmulched plots. In the second year of cropping, the weed seed bank was higher than in the first year in the Gliricidia sepium, and Leucaena,la le ucocephala mulch treatments by 41 and 65 % respectively. Senna siamea had a lower seed bank at all times of sampling. Talinum triangulare, Sedges, Old enlandia corymbosa and Ageratum conyzoides were the dominant species in the seed bank of all treatments. Mulched plots had a low seed bank of Oldenlan dia corymbosa, and Ageratum conyzoides in all treatments but Talinum triang ulare and sedges remained largely unaffected. Future weed control strategie s with mulches in this area should therefore target the first named species . For weed management, Senna siamea mulch was the most effective in reducin g seed bank.