Engine exhaust heat device for terminating cover crops in no-till vegetable systems

Authors: Kornecki, Ted; Prior, Stephen - Steve

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/26/2019
Publication Date: 9/19/2019
Citation: Kornecki, T.S., Prior, S.A. 2019. Engine exhaust heat device for terminating cover crops in no-till vegetable systems. Applied Engineering in Agriculture. 35(5):787-793. https://doi.org/10.13031/aea.13101.
DOI: https://doi.org/10.13031/aea.13101

Interpretive Summary: An exhaust heat-based apparatus with a supplemental electric heat strips was developed to terminate a cover crop without herbicide use. Temperature transfer efficiency from exhaust manifold to steel delivery tube was 23% with a tube temperature of 399 degree F contacting the cover crop. In contrast, transfer efficiency of heater strips was much greater (83 to 91%) at 860 degree F. Shortening the flexible piping between the exhaust manifold and heat delivery tube, and improving the insulating material encasing the flexible pipe could increase heat transfer. Termination rates for cereal rye and crimson clover by exhaust heat and combining exhaust heat with supplemental heat strips were similar to traditional mechanical termination using roller/crimpers. This heat-based apparatus can be a viable option for cover crop termination or weed control in organic systems where commercial herbicides are not allowed and where effective cover crop termination is essential for an optimum cash crop growth.

Technical 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 US, 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 oC against a flattened cover crop to damage plant tissue. The exhaust heat pusher apparatus was supplement with heater strips to enhance the cover crop termination process. Three electric heater strips (front, middle, back in direction of travel) were supplied with electrical energy by a generator powered by the tractor’s PTO and generated temperatures of 379 oC to 421 oC with a transfer efficiency of 83% to 91%. Results demonstrated that using the exhaust heat concept can be a viable option to terminate cover crops and control weeds. The exhaust heat transferring channel could be better insulated to exceed the lower 23% temperature transfer efficiency achieved by the device. Termination data during three weeks of evaluation indicate that the heat-based system was as effective as a mechanical roller/crimper.