Zink, T.A. and M.F. Allen
The effectiveness of organic mulch as a simple means of enhancing the restoration of disturbed lands by providing a competitive edge to native perennials, such as Artemisia californica (California sagebrush), over exotic annuals, such as Avena fatua (wild oat), was studied by investigating the effect of organic amendments on microbial activity and nitrogen immobilization through both soil analysis and aboveground plant growth. The addition of organic amendment resulted in an increase in microbial activity, a parallel increase in nitrogen immobilization, and no significant differences in total soil nitrogen. When the availability of nitrogen was reduced through increased immobilization, amended plots established an environment more conducive to native perennial shrubs, allowing them to out compete exotic annuals for water and nutrients. This simple procedure could have major implications for enhancing the restoration of disturbed lands.