On-farm evaluation of integrated weed management in no-till rainfed crops in semi-arid Morocco

Abstract

Field studies were conducted from 2012-13 to 2014-15 to investigate the dynamics of germinable soil seedbank, density and community composition of weeds in crop rotations of barley (Hordeum vulgare L.) + pea (Pisum sativum L.) and bread wheat (Triticum aestivum L.) in Oued Zem, semi-arid Morocco. In September 2012, the initial seedbank in 6 fields was 2354 seeds m -². When herbicide-free barley + pea forage mixture (cut for hay) was followed by bread wheat, seedbank reductions were 35% after the two years. When bread wheat was followed by herbicide-free barley + pea forage mixture, seedbank reductions were only 5% in two years. Prior to wheat harvest, weed densities were 82, The seedbank prior to planting and weed density prior to harvesting were strongly influenced by the most recent crop. Integrated weed management combining glyphosate before no-till planting, post-emergence herbicide use in bread wheat, haying barley + pea mixture, within the crop rotation (barley + pea/bread wheat) reduced weed seedbank by up to 35%, species richness by up to 47%, and weed density prior to wheat harvest or forage haying by up to 83%. Such changes suggest that integrated weed management practices in no-till system must be continued for more than 3 growing seasons to drastically reduce weed seedbanks and weed densities.