Precision metering of Santalum spicatum (Australian Sandalwood) seeds

The development of a seed metering device to mechanise the seed-sowing process for sandalwood is reported. Amongst the mass flow and precision type seed meters considered, the 'vacuum disc' type precision meter was deemed most suitable. A vSets vacuum disc seed meter was modified to accommodate seeds whose diameter ranged from 13.5 to 23.5 mm. Nine custom made discs were tested over three vacuum levels. The discs were analysed for their ability to achieve a seed spacing of 200 mm at a ground speed of 4 km h(-1). Accuracy was measured using the performance indices from ISO 7256/1-1984(E) as well as a modified coefficient of precision (CP3) index. Tests of twenty seven unique configurations were conducted with a sample of three hundred seeds. It was found that more than half of the configurations could singulate the seeds to a singulation level of 94%. Discs with seven 10 mm or 12 mm diameter holes, run at 17 kPa were found to be the most accurate configurations for the conditions considered and demonstrate that mechanisation of sandalwood seed sowing is possible. (C) 2013 IAgrE. Published by Elsevier Ltd. All rights reserved.