2018 ASHS Annual Conference

Weeds are a top management concern among organic vegetable farmers. Abrasive weeding is a newly developed non-chemical tactic that uses air-propelled abrasive grits to destroy weed seedlings within crop rows. Many different grit types are effective, but if organic fertilizers are used as abrasive grits it could allow farmers to integrate weed and nutrient management in one field pass. Our objective was to determine if abrasive weeding with organic fertilizer grits can be used in combination with agricultural mulches to increase weed suppression, yield, and profitability in organic vegetable systems. A two-year factorial experiment was conducted in organic red pepper (Capsicum annuum ‘Carmen’) at Urbana, IL with four replicates of five abrasive grit treatments (walnut shell grits, soybean meal fertilizer, Suståne composted turkey litter fertilizer, a weedy control, and a weed-free control) and four mulch treatments (straw mulch, bioplastic film, polyethylene plastic film, and a bare soil control). Abrasive weeding alone reduced in-row weed density by 35%, and mulch films alone reduced in-row weed density by 86%. Combining the two tactics reduced weed density by 94-98%, regardless of grit type. In-row weed biomass was greater in planting holes of films compared to bare soil, but abrasive weeding reduced that biomass by 77-87%. Films alone increased yield 6-fold, whereas films plus abrasive weeding increased yield 8-fold. Abrasive weeding combined with mulch films for weed control increased net income by an average of $29,260/ha, but that profit could be doubled if weed-free conditions are achieved via hand-weeding or two additional grit applications.