Hay mulching for revegetation of Alberta native grasslands

Dr. M. Anne Naeth | Professor and Director, Land Reclamation International Graduate School
Department of Renewable Resources
Faculty of Agricultural, Life & Environmental Sciences
University of Alberta

Dr. Naeth and co-investigator Dr. Federico Mollard (Post-Doctoral Fellow, Department of Renewable Resources) applied native hay and wheat straw to cultivated plots at the Mattheis Research Ranch to determine whether these techniques facilitate germination, emergence and establishment of seeded native forb and grass species. They found that hay mulching increased emergence of slender wheatgrass and blue flax seedlings relative to bare ground. Canadian milkvetch seedling emergence was more than ten times higher with hay mulch, and with low rates of straw mulch, than with bare ground. In general, low rates of straw mulch facilitated seedling emergence but had a neutral to negative effect when applied at high rates. High rates of mulch were detrimental to the reproductive success of blue grama grass. Overall, the results of this study showed that low mulch rates can increase native plant establishment during the critical first year of prairie reclamation as they were able to overcome microsite limitations. Mulching with straw or hay is an inexpensive method to conserve soil water and improve native grass and forb seedling establishment. Hay is a finer textured mulch than straw and is a safer option to improve seedling establishment if applying at higher rates. The reliability of seeding can be improved by adding species able to colonize bare ground – such as blue grama – to the seed mix.