Reducing the Integrated Harrington Seed Destructor Power Requirements through Chaff Fraction Optimization

Abstract

Abstract. Mechanical weed seed destruction during harvest is an effective method of reducing viable weed seed inputs to the seedbank. The commercialized Integrated Harrington Seed Destructor (iHSD) was developed for destroying weed seeds contained in the chaff residue exiting the harvester. Considered state-of-the-art in harvest weed seed control (HWSC), weed seed destruction is achieved without crop residue loss (burning or removal) and therefore, the iHSD is well suited to use in conservation cropping systems. However, as the iHSD is powered directly by the harvester its power draw impacts harvester performance. The objectives of this study were to determine the iHSD mill power requirements for effective weed seed destruction and to identify opportunities for decreasing these requirements. Using a torque-arm arrangement, the power requirements of an iHSD mill test rig powered by a PTO drive were measured. Wheat chaff containing a known amount of annual ryegrass () seed was passed through decreasing aperture sized sieves to obtain chaff size and seed distributions. The standard power demand to process chaff was ~54 kW, restricting the use of this system to large capacity harvesters. It was found that annual ryegrass seeds were concentrated in the chaff fraction passing through a 3 mm sieve. The power demand for processing this refined fraction was reduced by approximately a third to ~36kW. Efficient mechanical means to refine the chaff fraction to focus on the weed seed portion should be investigated. Keywords: Agricultural engineering, Conservation cropping, Efficiency, Harvest weed seed control, Herbicide resistance, Mechanical weed seed destruction,