2017 ASHS Annual Conference

In recent years, there has been a surge in organic vegetable production in Iowa, increasing to 1,264 acres, with $2.5 million in annual sales. Reduced tillage in vegetable operations provides multiple environmental benefits for soil conservation, as well as reducing machinery, labor and fuel costs. On organic farms, an innovative roller/crimper is used in lieu of herbicides to terminate cover crops. The objective of this research included an investigation of the feasibility of adopting conservation tillage practices for organic squash production. Cover crops of hairy vetch and rye were planted on October 18, 2015, at the ISU Neely-Kinyon Farm, Greenfield, Iowa, and terminated the following spring with a roller/crimper. Organic squash transplants (‘Delicata,’ Johnny’s Seed, Albion, ME) were planted on June 14, 2016. Cover crop biomass averaged 5,323 lb/acre across all plots. Treatments consisted of organic no-till and tilled cover crops, along with compost and mulch comparisons. At maturity, there was no difference in individual squash fruit weight or width among treatments, but fruit from no cover crop, compost, tilled, and mulched plots was greater in length than the other treatments. When yields from the two harvests were combined, yields from plots that received compost and were tilled were significantly greater than the other treatments, averaging 16,061 lb/acre. Squash yields from the treatment that contained no cover crop, compost, tilled, and no mulch, were equivalent to yields from plots with cover crops and compost, that were either no-till or tilled, which averaged 7,820 lb/acre. Soil results from previous years in the same treatments showed higher soil quality in no-till plots. Soil organic carbon, total nitrogen, and potential mineralizable nitrogen were higher in plots with cover crops. No-till plots had greater microaggregation and higher microbial biomass carbon compared to tilled plots. This shows that no-till is important for maintaining soil structure and enhancing soil microbial populations. The on-going challenge is to synchronize organic no-till vegetable crop growth with nitrogen release from cover crops to reap the full benefits form increased soil quality in organic no-till production.