Thomas P. Wilson, Miles C.E. Grafton
School of Agriculture and Environment, Massey University Private Bag 11 222, Palmerston North 4410, New Zealand

The New Zealand Spreadmark test which although proven to accurately measure the Coefficient of Variation (CV) of spreading equipment, entails a laborious procedure which is expensive to implement. This study aims to validate the accuracy of a newly developed test method based on the current one that hastens the process, making it increasingly cost effective. The proposed solution reduces the amount of trays used to collect and measure the fertiliser spread pattern. The proposed method reduces the number of trays by half, placing them one meter apart compared to the current industry standard of half a meter. An electronic tray weighing system developed by EuroAgri streamlines the process. This allows the scales to be, zeroed, after each pass by removing the need to empty trays. Collated data of previous Spreadmark tests sourced from certified Spreadmark testers. This had the support of the Fertiliser Quality Council that manages the scheme used in the study. Tray weights of each successive 0.5 and 1.0 metres were, averaged to imitate tray spaces of 1.0 metre. The 1.0 metre tray spacing showed a strong correlation to the 0.5 meter spaces, maintaining the normal distribution pattern of the spread fertilizer albeit in a slightly lower definition. Coupled with the electronic scales that reduces human error, this forms an accurate and efficient method of undertaking testing. This new system could have marked effects upon the future of spreader testing in New Zealand, including higher proportions of conforming spreaders (due to increased time and cost effectiveness) leading to lower field coefficient of variation (CV). As a result, fertiliser efficacy would increase, as would financial returns.
Keywords: Spreadmark test, tray spacing, weigh cells, coefficient of variation, CV, testing efficiency

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