2018 ASHS Annual Conference

Opinions on the “soil balancing” philosophy of soil management among growers and private- and public-sector grower advisors and researchers range wide and, so far, rarely achieve consensus. Proponents, including increasing numbers of specialty crop growers (many sustainable-organic) and some advisors, report that soil chemistry -- specifically, percentages and ratios of calcium, magnesium, and potassium – can be altered through applications of lime, gypsum, and other materials to improve soil physics (tilth) and biology and, thereby, crop yield and quality and weed control, also. Investigators and other advisors, however, report that soil balancing claims are unsupported by the data (at minimum) and potentially injurious to farms (at worst). That disconnect is both a problematic trend and important opportunity. As part of a larger effort to understand the use and outcomes of soil balancing as practitioners do while also providing needed data, eight certified-organic main plots (17.1 m x 18.3 m) were established in 2015-2018 at the OSU-OARDC in Wooster, OH. Main plots contained two (17.1 m x 9.1 m) subplots based on their having received an annual application of composted dairy manure every year since 2003 or no compost application. Three (5.3 m x 9.1 m) sub-subplots/subplot were created on June 11, 2015 by applying one of three soil amendment treatments: 1) gypsum (1681.5 kg ha^-1), 2) potassium sulfate (560.5 kg ha^-1), and 3) gypsum + potassium sulfate (same rates). Rock phosphate was also applied at 560.5 kg ha^-1 to minus-compost subplots. Treatment applications were repeated at the same locations each mid-May 2016-2018. Sub-subplots were direct seeded with four rows of both edamame soybean and dwarf popcorn on June 12, 2015, May 25, 2016, and May 23, 2017, with edamame being reseeded on June 21, 2016 and June 14, 2017. Two rows of butternut squash were also direct-seeded into each sub-subplot on June 18, 2015, May 31, 2016, and May 26, 2017. All crops received multiple applications of fish fertilizer (analysis of 2-4-1) each season either by hand (edamame, popcorn) or via fertigation (squash). Percent stand, above-ground canopy development, mass of mature leaves at the onset of reproductive growth, and crop yield (total, marketable) and quality were recorded each year along with measures of soil macro- and micronutrient levels. Treatments have resulted in few significant differences in either plant growth, or crop yield or quality to date. Weed seedbank analysis and comprehensive assessments of grower attitudes and farm economics are also underway.