Abrasive-weeding is a novel weed management tactic with potential to reduce tillage and hand-weeding
in organic agriculture. However, abrasive-weeding has not been tested in vegetable cropping systems
and growers are interested in the potential for using organic fertilizers as abrasive grits to control weeds
and supplement crop nutrition in one field pass. A two-year field study was conducted at the University
of Illinois Sustainable Student Farm to determine the effect of air-propelled abrasive grit type, including
organic fertilizers, and application frequency on weed density and biomass and crop yield and
marketability in organic tomato (Solanum lycopersicum L.) and pepper (Capsicum annuum L.) cropping
systems. Abrasive-grits, including granulated walnuts shells and maize cobs, greensand fertilizer, and
soybean meal, were applied via compressed air between one and four times within planting holes of
plastic mulch. Weed density was quantified 25 or 37 days after the first application and weed biomass
was harvested at the end of the growing season. Tomatoes and peppers were harvested ripe and graded
for marketability. Two applications of abrasive grits, regardless of grit type, reduced weed density by 63%
and 80% in tomato and pepper, respectively. Broadleaf weeds were more susceptible to abrasive-weeding
than grass weeds. Abrasive-weeding reduced final weed biomass by 69e97% compared with the weedy
control, regardless of grit type or application frequency. Total tomato yield was up to 44% greater in
treated plots compared with the weedy control, whereas total yield gains in pepper (up to 33%) were
only approaching significance (p ¼ 0.09). Yield and the marketability of fruit was not negatively affected
by grit application, despite minor stem and leaf tissue damage after applications. Organic fertilizers used
as abrasive grits in this study could contribute between 35 and 105 kg N ha1, which may improve the
functionality and economic feasibility of abrasive-weeding.