Precision method for measurement of characteristics during an electric weeding treatment : a thesis presented in partial fulfilment of the requirements of the degree of Master of Engineering (Mechatronics) at Massey University, Manawatu, New Zealand

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A method is proposed that allows measurement of electrical phenomena during an electric weeding discharge, to allow development of a viable non-herbicide weeding option for agriculture. Electric weeding – killing plants with high voltage electricity – has been researched since the 19th century, but the mechanism for plant death is not yet fully defined. There has also been little research into the localised electrical effects and how the treatment could be optimised based on the plant type and environmental conditions. The proposed method allows separation of the system into the ‘plant’ and the ‘root-soil’ sub-systems, and allows measurement of the division of the voltage and energy between them. For plants where the dimensions of the stem can be mechanically measured – such as many dicotyledon (broadleaf) weeds – the method allows calculation of the electric field strength, current density, and energy volume density within the plant tissue. It is suggested that these parameters can be associated with plant survival rates to develop understanding of the mechanism for death and to optimise the energy and time of electrical weeding systems that are developed in the future.
Figs 7 (=Diprose et al., 1980 Fig 5 & 8 (=Ellwanger et al., 1973 Fig 3 A&C have been removed for copyright reasons. Fig 1 is re-used under a Creative Commons Attribution 4.0 International (CC BY 4.0) license. Permission was obtained for re-use of Figs 6 A&B, 9 & 10.