Engine Exhaust Heat Device for Terminating Cover Crops in No-Till Vegetable Systems

Abstract

Abstract. Sustainable no-till practices utilize cover crops to protect the soil surface and to improve soil properties. Proper cover crop management is the key for successful planting of the main crop directly into cover crop residue without interfering with planting operations. In the Southern United States, the recommended time to plant cash crops into desiccated residue cover is typically three weeks after cover crop termination when the termination rate exceeds 90%; this minimizes nutrient competition between cover and cash crops. The standard method to manage cover crops is mechanical termination utilizing rollers/crimpers. This technique flattens and crimp plants to expedite termination. Another method that has been used in agriculture is to injure (desiccate) plants utilizing an external heat source. An example of utilizing an external heat source has been used in vegetable production for weed control. However, there is a need to evaluate another heat source such as exhaust heat generated by internal combustion engines (which otherwise is completely wasted) for cover crop termination effectiveness. To achieve cover crop termination with exhaust heat, a prototype was invented on board a walk-behind tractor powered by a single cylinder gasoline engine from which exhaust heat was funneled from the exhaust manifold to a perforated steel rectangular tube maintaining 204°C against a flattened cover crop to damage plant tissue. The heat pusher was equipped with electric heater strips to provide supplemental heating. Three electric heater strips (front, middle, back relative to the direction of travel) were supplied with electrical energy by a generator powered by the tractor’s PTO and generated temperatures of 379°C to 421°C with a temperature transfer efficiency of 83% to 91%. The performance of the unit with and without supplemental heating was compared with standard mechanical roller/crimper. Results demonstrated that using the exhaust heat concept can be a viable option to terminate cover crops. The exhaust heat transferring channel could be better insulated to exceed the lower 23% temperature transfer efficiency achieved by the device. Cover crop termination data during three weeks of evaluation indicated that the heat-based system was as effective as a mechanical roller/crimper. Keywords: Cereal rye, Cover crop termination, Crimson clover, Exhaust heat, Flattening cover crops, Heat transfer, Heater, Plant termination.