Agronomic responses of transitioning organic grain rotations employing multi-tactic tillage and cover cropping strategies

Abstract

The transition from conventional to organic farming presents challenges and opportunities for enhancing agricultural sustainability. This study evaluated the impacts of four organic grain cropping systems, varying in tillage, cover crops, fertility management, and rotational sequence, on cover crop biomass, grain yield, and weed suppression over a 3-year transition period. The cropping systems included (i) maximum yield system (MYS) for maximizing production; (ii) sustainable yield system (SYS) for balancing yield and ecological benefits; (iii) ecologically conscious system (ECS) for maximizing ecological benefits; and (iv) low input system (LIS) for sustaining the system without external fertility inputs. Implemented in a 3-year rotation of soybean (Glycine max), wheat (Triticum aestivum), and corn (Zea mays), these treatments utilized a full-entry design with all three cash crop phases repeated annually. The MYS and SYS treatments achieved the highest cover crop biomass (7–12 Mg ha⁻¹ Year⁻¹) and weed suppression, while LIS had the lowest biomass (0–6 Mg ha⁻¹ Year⁻¹) and highest weed pressure. Fertilized treatments (MYS, SYS, and ECS) consistently produced satisfactory yields, with Year 3 averages of 4.66 Mg ha⁻¹ for corn, 2.47 Mg ha⁻¹ for full-season soybean, 4.06 Mg ha⁻¹ for wheat, and 1.5 Mg ha⁻¹ for double-crop soybeans. Also, agronomic outcomes (biomass and grain yield) of less-tilled SYS and ECS were on par with the most-tilled MYS system. Thus, this research highlights the potential for reducing tillage intensity in organic grain farming without compromising agronomic outcomes in the southeastern United States.