Enhancing native seedling establishment on degraded agricultural land with topsoil pellets

Abstract

Background and aims Agricultural activities can degrade soils and promote weeds, posing challenges in restoring native plant species. Removing contaminated topsoil, a restoration method used in some agricultural systems, reduces soil nutrients, and eliminates weeds both aboveground and in soil seed bank before direct seeding. However, it also diminishes native soil seed banks and beneficial soil microbes. We investigated the potential of encasing seeds in pellets containing fresh topsoil to improve seedling performance and establishment on a degraded grassy woodland where topsoil had been removed. Methods We tested various pellet recipes, including one using commercial ingredients and three with different topsoil proportions (30%, 50%, and 70%). The study was conducted in a degraded grassy woodland in southeastern Australia, where topsoil was removed. We explored the effect of these pellet varieties on seedling emergence and growth of six native species common in this community, as well microbial activity in the soil. Results Pellets significantly improved the emergence of Chrysocephalum apiculatum, providing evidence of their effectiveness. However, pellets significantly reduced Arthropodium milleflorum and Glycine tabacina emergence. Linum marginale and Rytidosperma caespitosum emergence remained unaffected by pellets. One species, Bothriochloa macra, had insufficient emergence for analysis. The microbial activity of the soil surrounding Rytidosperma caespitosum seedlings was significantly improved by pellets, with no significant effects observed for other species. Conclusion Overall, our results demonstrate that using seed enhancement technologies in combination with direct seeding can improve the emergence of one native species on degraded agricultural soil, potentially facilitating the recovery of degraded ecosystems.