2017 ASHS Annual Conference

On small, diversified organic vegetable farms (<10 acres), growers need reduced tillage strategies that work across a range of crops and within a complex production system. These growers may effectively reduce tillage by dividing fields into permanent beds that restrict traffic and compaction to between-bed areas year after year. To further advance these systems, we are evaluating the agronomic, ecological and economic effects of different reduced tillage systems in permanent beds for organic vegetables in Freeville, NY and Monmouth, ME, over four years. In 2016 (second year) we managed winter squash with six levels of tillage intensity (high-deep rototilling to low-no-till). We compared two no-till systems, one with a tarp placed on the soil surface for six weeks prior to planting. These impermeable, durable black plastic covers suppress weeds between crops, either ahead of planting or after harvest, providing greater labor flexibility for crop management. Within each tillage system, we compared three surface mulch treatments: straw, compost or none. We monitored tillage and mulch effects on the soil environment (moisture, temperature, nutrients), weeds, time spent in all field operations (i.e. hand weeding, applying mulches), and crop quality and yield. At both locations, mulches significantly affected yields and compost was the most productive. In NY, straw had the lowest yields in part because plant numbers were reduced by pest pressure. In ME, straw improved yields compared to the un-mulched system. At both locations, shallow rototilling gave similar results to deep tillage. In both years, tarps killed emerged weeds and created weed-free planting conditions without soil disturbance, especially in the unmulched treatment. Tarped beds reduced hand labor for hand weeding to 1/3 of the time required for no-till without tarps (yr1). Tarping also dramatically reduced the amount of weeds present at crop harvest in the unmulched crop. Soil temperatures were greater under tarps for each of the mulches. When tarps were removed, the amount of soil nitrogen available to plants was over four times greater than the unmulched rototilled soil (yr2). Tarp effects on crop yields depended on the year and mulch used but were similar to or greater than the other tillage systems. Tarped beds yielded similar to (NY) or greater than (ME) the non-tarped no-till system. Tarping could be a valuable tool for organic farmers to effectively minimize tillage while improving weed control and crop productivity.