2017 ASHS Annual Conference

Conservation agriculture practices such as reduced tillage, cover cropping, and compost additions may help build soil organic matter and provide important services within vegetable cropping systems; however, these practices can also present management challenges, particularly in organic systems. A long-term field experiment was initiated in 2009 comparing full width conventional tillage (CT) to strip tillage (ST) under two rates of dairy compost addition (0 or approximately 3 dry ton ha^-1 yr^-1). The experiment was transitioned to organic management beginning in 2012, and in 2014 a 3-year organic sweet corn-broccoli-snap bean rotation was implemented via subplots within the main tillage and compost treatments. Vegetables were preceded in each year by cereal rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth; sweet corn and broccoli only) cover crops zonally planted to between-crop row and in-row areas, respectively. Effects on vegetable yield and quality, soils, and weed management were evaluated. Over the course of the experiment, ST resulted in equivalent or higher total yields of sweet corn and snap beans relative to CT, but resulted in equivalent or lower total yields of broccoli. In 2015, significantly higher total snap bean yields and marketable broccoli yields in ST were associated with reduced seed corn maggot damage in beans and lower incidence of brown bead in broccoli. Compost application resulted in equivalent or higher broccoli and bean yields, but equivalent or lower sweet corn yields (along with apparent nutrient deficiency symptoms). Potential soil organic matter benefits from ST were tempered by in-season reductions in soil inorganic N availability in some years. While cover crop residues in ST provided weed suppression, high residue conditions also presented occasional challenges for managing problematic summer annuals later in the season. Use of finger weeders in the crop row, and rolling cultivators between-row were tested and found useful for improving weed management where residue was present. Long-term investigations of the cumulative impacts of conservation practices within typical organic vegetable crop rotations are important for gaining a more complete understanding of potential on-farm outcomes over time.