Designing Farmers’ Goal-oriented Organic Grain Rotations to Optimize Agronomic, Economic, and Ecological Outcomes in Tennessee
Project Director
Sindhu Jagadamma
Year Funded
2020
Award Number
2020-51106-32362
Funded Institution
University of Tennessee
Grant Program
ORG (Organic Transitions)
USDA NIFA Report (alternate)
Project Overview
This project conducted field trials at two sites in Tennessee to compare four 3-year organic corn-soybean-wheat rotations with different farmer-identified goals:
- T1 – maximum production: full tillage, cover crops before and after corn, poultry litter (PL) 2 t/ac for wheat and 6 t/ac for corn, second soybean double-cropped after wheat.
- T2 – high production, reduced tillage, same as T1 except no-till soybean plantings.
- T3 – minimum tillage, 2 tillage passes in 3 years, cowpea cover in lieu of double-cropped soybean, PL as above.
- T4 – minimum tillage and inputs, 2 tillage passes, no PL, red clover + timothy interseeded into wheat ahead of corn.
System impacts on cover crop biomass, grain yields, weeds, pests, diseases, nutrient cycling, soil health, greenhouse gas (GHG) mitigation, and farm economics were documented. Systems T1 and T2 had the highest cover crop biomass and fewest weeds, while T4 had the lowest cover crop biomass and most weeds. T1, T2, and T3 gave similar yields, while omitting PL in T4 reduced yields. A problem with establishing no-till soybeans in heavy residues was corrected by using row-cleaners to ensure good seed-soil contact.
Active and total soil organic carbon (SOC) increased in all treatments, with the greatest accruals in T2 and T3. Cumulative (3 year) nitrous oxide (N2O) emissions were highest in T1, intermediate in T2 and T3, and lowest in T4 (~29, 19, and 7 kg N2O-N/ha). The high rate of PL on corn sustained corn yields and boosted cover crop biomass, but generated the most N2O, especially when PL was tilled in with cover crop residues.
Farmer Takeaways
- Cover crops, a diverse crop rotation, and organic inputs like poultry litter can build SOC and sustain soil health and organic crop yields, even in high tillage systems.
- High biomass cover crops reduce weeds and improve grain yields.
- Reducing intensity and frequency of tillage can enhance SOC accrual and reduce nitrous oxide (N2O) emissions without serious yield tradeoffs.
- High rates of poultry litter create N surplus and promote leaching and N2O emissions.
- Early maturity and double-crop soybean varieties enhance yield stability and reduce weather risks.
- Using row cleaners for no-till soybean planting into roll-crimped cover crops improves stand establishment and yield.
Project Outputs
Video Series: Bioformulations & Organic Grain Mastery
Neelipally, R. T., Saha, D., and Jagadamma, S. 2024. Defining boundaries and conceptual frameworks for ecologically focused agricultural systems. Journal of Soil and Water Conservation, 79(4), 61A-65A.
Neelipally, R. T., Saha, D., Cui, S., and Jagadamma, S. 2025. Agronomic responses from diverse tillage and cover crop integrated organic grain transitioning systems, Agronomy Journal 117(3).
Chhetri, A., Jagadamma, S., and Saha, D. 2023. The impact of organic grain production systems on soil-derived greenhouse gas emissions. ASA-CSSA-SSSA International Annual Meeting, Oct. 31-Nov. 1, Saint Louis, MO. (Oral).
Chhetri, A., Jagadamma, S., and Saha, D. 2024. Soil nitrous oxide (N2O) emissions and greenhouse gas budget from organic cropping systems. ASA-CSSA-SSSA International Annual Meeting, Nov. 10-Nov. 14, San Antonio, TX (Oral).
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