Masarei, M, Guzzomi, AL, Merritt, DJ & Erickson, TE 2019, 'Improvements to mechanical direct seeder design guided by the optimal sowing depth of soft spinifex (Triodia pungens)', in AB Fourie & M Tibbett (eds), Mine Closure 2019: Proceedings of the 13th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 199-208, https://doi.org/10.36487/ACG_rep/1915_17_Masarei
(https://papers.acg.uwa.edu.au/p/1915_17_Masarei/)
Abstract: The ability to reliably and efficiently restore degraded ecosystems at scale is a major challenge. Restoration on a mine site typically consists of either the planting of cultivated nursery stock or the direct seeding of seed onto site to reinstate native plants and ecosystems. At scale, planting seedlings can be extremely costly and time consuming and therefore, restoration practitioners have moved towards mechanical direct seeding methods. In many circumstances, however, mechanical direct seeding is unreliable and most mechanisms lack the versatility needed to plant a variety of native species in a range of sowing environments. Results of a global survey of restoration practitioners uncovered that seeding depth precision and accuracy is extremely important when distributing many native seeds. In order to guide improvements to the design of native seeders that are used in the Pilbara region of Western Australia, we studied the maximum and optimal emergence depth of a species crucial to restoration in the region, Triodia pungens (soft spinifex). Results showed that the current practice of broadcasting seeds on the soil surface may be inadequate to facilitate germination, and that covering seeds to 5 mm yields optimal emergence. Seedling emergence dropped off considerably at 10 mm with almost no emergence occurring once seeds were sown to 30 mm. Most mechanical seeders currently in operation are unable to control depth to this level of precision, particularly on the rocky and uneven terrain associated with mine waste dumps. Future designs should focus on improving depth control in such conditions.

Keywords: restoration, direct seeding, mechanical seeders, Triodia pungens