Weed Control with Crop Residues in Vegetable Cropping Systems

Summary Crop residues have many potential uses in cropping systems, among which are imparting weed control. The principal objective of this research was to evaluate residues from corn (Zea mays L.), soybean (Glycine max Merr.), and sunflower (Helianthus annuus L.) for their effects on weed control and on crop productivity of tomato (Lycopersicon esculentum Mill.) and summer squash (Cucumis pepo L. var. melopepo Alef.). In one experiment, residues were imported to the vegetable plots and applied as surface mulches or incorporated shallowly into the ground. In another experiment, the residues were grown on site as cover crops in the year preceding vegetable production and disked into the plots. Application of imported residues was more effective in weed control and yield enhancement than the cover crop residues. Imported residues were effective in control of early emerging weeds, whereas with the cover crops supplemental weed management was required for early weed control. Weed control did not differ substantially with species of residue, but control increased as amount of incorporated residues increased from 6 to 24 Mg/ha. Weed control with residue incorporation at 6 Mg/ha was as effective as a mulch of 24 Mg/ha. If weed control was imparted by the residues, crop yields with any residue treatment were equivalent to those from plots kept relatively weed-free by tillage. Yields did not vary with amounts of residues applied. Weed control by the residues was effective in growing seasons or months of growing seasons with below-normal or near-normal rainfall. High rainfall destroyed the weed-controlling potential of the mulched or incorporated imported residues or cover crop residues. This research demonstrated that crop residues impart weed control and that in years with adequate control, yields of crops will be equal to those in plots with rigorous control by tillage. In times of high rainfall during crop production or with use of residues from cover crops, supplemental weed management practices will be needed.