Cover crops and mulches influence weed management and weed flora composition in strip-tilled tomato (Solanum lycopersicum)

This study was conducted in the Mediterranean environment of Central Italy from 2011 to 2013 in order to evaluate the effects of winter cover crops and their residues on the weed composition in a cover crop-tomato sequence. Treatments consisted in: 5 soil managements {3 cover crop species [hairy vetch, phacelia, white mustard]}, winter fallow mulched with barley straw before tomato transplanting, and conventionally tilled soil; 2 nitrogen fertilization levels [0 and 100 kg N ha-1]; and 2 weed management levels [weed-free and weedy] on tomato. Cover crop residues were left on the soil surface and arranged in strips which were used as beds for tomato seedlings transplanted in paired rows. Tomato was strip tilled between the tomato paired rows. At tomato harvesting, weed aboveground biomass and density was higher in tomato nitrogen fertilized than unfertilized tomato, except in hairy vetch and oat which showed similar values. Hairy vetch was the most suppressive species as cover crop and as dead mulch with the highest production of residues, while phacelia and mustard were not suitable for controlling weeds. Tomato yield increased in nitrogen fertilized and weed-free treatments, except in barley straw mulch which showed similar values among the weed management treatments. Strip mulches caused a change in weed species composition which was mainly composed of perennial ruderal weeds, while in tilled soil the weed flora was dominated by annual photoblastic weeds.3n