Profitability of abrasive weeding in organic grain and vegetable crops

Authors: WORTMAN, SAMUEL - University Of Nebraska; Forcella, Frank; LAMBE, DAVID - University Of Nebraska; CLAY, SHARON - South Dakota State University; HUMBURG, DANIEL - South Dakota State University

Submitted to: Renewable Agriculture and Food Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/26/2018
Publication Date: 9/21/2018
Citation: Wortman, S.E., Forcella, F., Lambe, D., Clay, S.A., Humburg, D. 2018. Profitability of abrasive weeding in organic grain and vegetable crops. Renewable Agriculture and Food Systems. 1-6. https://doi.org/10.1017/S1742170518000479.
DOI: https://doi.org/10.1017/S1742170518000479

Interpretive Summary: Organic farmers have limited options for controlling weeds. Excessive tillage harms soil and hand-weeding is expensive and increasingly unavailable. A new mechanical option for in-row weeding involves the use of abrasive grit. However, the profitability of abrasive grit-weeding never has been explored. Here we compare the profitability of grit-weeding to hand-weeding for organically grown but low-value grain (corn) and high-value vegetables (tomato, and green and red peppers). Grit-weeding was not profitable in organic grain corn compared to hand-weeding, although its economic viability could increase with improvements in this new technology. In contrast, grit-weeding was profitable in organic vegetables, with the greatest profits occurring in the highest-valued crop, red pepper. As costs of manual labor increase, and as its availability decreases, the profitability of grit-weeding may become more attractive, especially with improvements in equipment and the on-farm supply of gritty materials. These results will be of interest to organic farmers, crop advisors, extension educators, agricultural implement manufacturers.

Technical Abstract: Weed competition, especially within the crop row, limits the productivity and profitability of organic crop production. Abrasive weeding, a mechanical alternative to hand weeding, uses air-propelled grits to control small weed seedlings growing within the crop row. Recent research has demonstrated the successful use of abrasive weeding to reduce weed competition and increase yields in organic maize (Zea mays), tomato (Solanum lycopersicum), and green and red pepper crops (Capsicum annuum), but the profitability of this weed control tactic has not been assessed. Our objective was to determine the profitability of abrasive weeding using empirical yield data from three previously published studies, a range of crop prices and revenues, and a range of costs for wages, grit applicator ownership, tractor use, abrasive grits, and fuel. Results suggest that abrasive weeding is not profitable in organic maize production, and may reduce net income by $223 - $3,537 per ha depending largely on the cost of abrasive grits and the cost to own a four-row grit applicator ($736 - $2,105 per year). However, abrasive weeding was less expensive than hand weeding, especially as the scale of production increased. Abrasive weeding was profitable in tomato and pepper crops and increased net mean income by $12,251 to $33,265 per ha. However, abrasive weeding efficacy is not yet 100%, and hand weeding for weed-free conditions was always the most profitable approach to in-row weed management in vegetable crops. Profit potential of the hand-weeded, weed-free treatments demonstrates the importance of weed control in high-value specialty crops – even those grown in plastic mulch film. Despite the profit potential for hand weeding observed here, labor is increasingly difficult to source, retain, and afford, and abrasive weeding offers a mechanical alternative with 66% less labor required. Further research is needed to improve efficacy of abrasive weeding and to reduce the cost of abrasive grits and application.