Robert Gallagher1, Dennis Pittmann2, Amanda Snyder2, Rich Koenig2, Kathleen Painter2, Herbert Hinman2, E. Patrick Fuerst2, and Ian Burke2. (1) The Pennsylvania State University, Department of Crop and Soil Sciences, University Park, PA 16801, (2) Washington State University, Department of Crop and Soil Sciences, Pullman, WA 99164-6420
The organic transition phase is a three-year period when a cropping system must be free of the synthetic fertilizers and pesticides commonly used in conventional agriculture. During this transition period, the crops produced do not qualify as certified organic, and price premiums cannot be obtained. A farmer may also be vulnerable to economic losses due to weed and pest infestations, inadequate soil fertility, and dockage penalties due to poor crop quality. The objective of our study was to determine how utilizing crop rotations may reduce any economic losses during the transition period, while building soil fertility through the use of green manures to maximize gains when the farm becomes certified organic. Nine transitions systems were designed to integrate legumes or forages for fertility building (nitrogen), and to provide opportunities for mechanical weed management to control weeds and deplete the soil weed seed bank. In summary, our most successful transition was the forage (alfalfa + red clover + spring pea), resulting in the highest spring wheat yields, the fewest weeds, the highest earthworm populations and a small net economic gain after four years. The winter pea green manure systems were also effective at building soil fertility and controlling weeds, but resulted in economic losses. Systems that included spring pea grown for grain were prone to insect pests and weed infestations. A reduced tillage system consisting of sweep plow + rotary harrow + rotary hoe worked well to manage annual weeds, but did not effectively suppress perennial weeds such as field bindweed. Winter wheat yield data from year 5 of the study will also be presented.
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