2017 ASHS Annual Conference

Spinach production in the southeastern U.S. faces obstacles of high humidity and temperatures, leading to poor crop growth, high disease incidence, and premature bolting. As a short season crop, spinach can be advantageous for a grower’s rotation system. However, poor germination may lead to inadequate crop stands, with high soil temperatures exacerbating the issue. Compost can affect soil physical, chemical, and biological properties, leading to improved plant productivity and environmental quality. However, the use of compost in organic spinach production in Florida has not been well examined. Side-by-side open field and high tunnel organic spinach trials were conducted in fall 2016 (Citra, FL) in a split-split plot design with three replications of two amendment application treatments, broadcast and banded, and two cultivars, ‘Corvair’ and ‘Reflect’, to assess potential production impacts of the production systems and amendment treatments. Compost made from 50% food waste and 50% yard waste was applied at 44.8 MT/ha. The broadcast treatment was tilled while the banded treatment was raked. Seeds were sown directly into the banded compost or into the tilled, broadcast treatment. The banded treatment resulted in a full stand while the broadcast treatment resulted in sparse germination. The banded treatment also resulted in a faster growth rate, with harvests at days 33, 47, and 62 compared with harvests at days 39 and 60 for the broadcast treatment. Subsequent greenhouse and open air germination experiments of ‘Corvair’ were conducted in spring 2017 using a split-split plot design with four replications of two amendment treatments, broadcast and banded, and three seeding depths, 6.4 mm, 12.7 mm, and 19.1 mm. After the conclusion of the 15-day study, germination percentage in the banded treatment was significantly greater, at 92.5%, compared with 45.5% in the broadcast treatment, while planting depth effect was not significant. Temperature effects were shown as the cooler, open-air setting resulted in a significantly greater germination percentage than the warmer greenhouse. Moreover, no significant difference in banded treatments between settings was found, while the broadcast, open-air treatment showed significantly greater germination than the broadcast, greenhouse treatment. The results from the germination trial not only validate the effects observed in the field trial, but also indicate the potential for banded compost to alleviate high soil temperature effects on spinach germination and emergence.