Diversifying Organic Inputs to Improve Soils Supporting Organic Vegetables in Southeastern USA
Project Director
Rongzhong Ye
Year Funded
2020
Award Number
2020-51106-32363
Funded Institution
Clemson University
Grant Program
ORG (Organic Transitions)
USDA NIFA Report (alternate)
Project Overview
Field trials were conducted with a tomato-cucumber (double crop)-sweet corn-tomato rotation in Florence, SC (coastal plain) and Chattahoochee Hills, GA (piedmont) to determine whether diversified organic inputs and conservation tillage can build organic matter and fertility in the region’s challenging Ultisol soils. Factorial treatments included cover crops (rye, vetch, rye + vetch, or none), reduced vs full tillage, and with and without composted poultry manure (3-4-3) at 2.4 Mg/ha-yr. Data were collected on soil organic carbon (SOC) and nitrogen (N), microbial C, N, and P cycling, soil physical properties, and crop nutrient use efficiency, yield, and quality.
Farmer Takeaways
(1) Legume and non-legume cover crops, manure compost, and other organic amendments have distinct and complementary impacts on soil microbial communities, nutrient cycling, and soil fertility. Diversifying inputs can optimize soil health outcomes.
(2) Cover crops sustain soil life, enhance nutrient mineralization, mitigate tillage impacts on soil organic matter, and reduce nitrous oxide (N2O) emissions.
(3) Timely planting, sufficient duration, and fertilization when warranted can boost cover crop biomass and associated benefits.
(4) Concentrated organic N sources like poultry litter or legume green manure provide plant-available N but may not build soil organic matter and may reduce microbial diversity.
(5) Crop responses to cover crops and manure compost may vary with crop species, locale, and soil health status.
Project Outputs
Wang, Z., Saski, C., Williamson, C., Campbell, B., Ye, R., 2024. Crop cover and manure compost: Their varied effects on nitrogen availability and nitrogen cycling functional gene abundances in sandy soils for organic farming. Applied Soil Ecology 200, 105446.
Oliver, F. E., & Ye, R. 2023. Carbon and Nitrogen Cycling As Influenced By Tillage, Cover Crops, and Manure in Organic Agriculture. ASA, CSSA, SSSA International Annual Meeting, St. Louis, MO.
Wang, Z., Ye, R., & Saski, C. 2023. Hairy Vetch and Manure Compost Improved Soil Nitrogen Availability and Reduced Bacterial Diversity in Organic Vegetable Production ASA, CSSA, SSSA International Annual Meeting, St. Louis, MO.