Dobrowolski, MP 2019, 'Combining seed burial, land imprinting and an artificial soil crust dramatically increases the emergence of broadcast seed', in AB Fourie & M Tibbett (eds), Proceedings of the 13th International Conference on Mine Closure
, Australian Centre for Geomechanics, Perth, pp. 667-678.
Seedling emergence from broadcast seed is notoriously low in mining rehabilitation. At Iluka Resources’ Eneabba mine in the Mid West of Western Australia, eight-fold more seedlings emerged under ideal nursery conditions in 2015 than when that seed was broadcast in the field. Unlocking this potential in broadcast seed is critical to establish the desired plant density and species diversity of restored kwongan shrubland vegetation.
Erosion, both wind and water, is a major factor affecting seedling emergence in newly rehabilitated mines sites. To control wind erosion at Eneabba, Iluka applies a crust of dilute, non-toxic bitumen emulsion to the sandy soil surface. This crust degrades over a few years but does not inhibit germination. It allows seedlings to emerge and establish under windy conditions, common at Eneabba, holding the seed in the soil matrix for germination to occur and eliminating the sand-blasting that kills newly emerged seedlings. Combining this crust application with ripping-mounding to prevent water erosion in 2016 increased seedling establishment almost two-fold.
Land imprinting, a technique developed in the 1970s, reduces rainfall runoff and increases infiltration and nutrient/organic matter accumulation thereby improving seedling emergence and establishment. However, the imprints erode too quickly in sandy soils like those at Eneabba. A trial in 2017, combining land imprinting and bitumen emulsion crust increased seedling emergence more than two-fold for broadcast seed and three-fold for topsoil-derived seed.
Burial of the diverse sized and shaped seed, for improved germination, was achieved in 2018. This combined with land imprinting and crust application increased seedling emergence from broadcast seed by 50% on the 2017 trial.
Data from large-scale field trials of these rehabilitation practices and their innovative combination will be presented to illustrate their effectiveness and applicability in other projects. New, custom-built seeding, land imprinting and crust application equipment used in 2019 Eneabba rehabilitation will be unveiled.
Keywords: revegetation, land imprinting, mining rehabilitation, seed