Mechanical and Thermal Weed Control in Organic Tilled and No-till Production.

Effective weed control is one of the most yield-limiting factors in organic corn and soybean production. Additionally, the amount of tillage needed to control weeds in organic practice is often criticized for its negative impacts on soil quality. Previous research conducted at the University of Missouri as well as other institutions has shown that some early season weed control can be gained through the use of no-till planting into a crimped cover crop. Because weeds do eventually emerge through even thick cover crop residue, we are investigating methods to control these weeds and improve the success of organic no-till. The two secondary methods of weed control we are using are between-row mowing and hot water spray. When compared to cultivation, a crimped cover crop coupled with between-row mowing has led to improved weed control and higher yields in soybean. Although weed control in corn planted into a crimped cover crop with between-row mowing is similar to control in both cultivated and propane-flamed treatments, yield reductions from delayed emergence and nitrogen deficiency caused by the decaying cover crop residue make organic no-till less successful in corn. Hot water spray has proven to be effective weed control on very small weeds. Weeds that emerge through the crimped cover crop residue are generally already too large and vigorous for effective control with hot water.