Reducing crested wheatgrass (Agropyron cristatum (L.) Gaertn) and improving soil health to facilitate native plant restoration

Abstract

Land managers seek to restore diversity of native plant species to areas dominated by introduced crested wheatgrass (Agropyron cristatum (L.) Gaertn.; CWG). This study was initiated by the Bureau of Land Management (BLM) to find the most effective treatment or treatment combination in reducing CWG cover and enhancing soil for native species establishment. Our treatments used alone and in combination were tillage, herbicide, cover crops, and a soil amendment.

We found that CWG reduction was dependent on tillage or herbicide, with the highest reduction in their combination. The combination of these included the addition of cover crops and amendment but still led to the lowest total microbial abundances, along with the lowest fungal-to-bacterial ratio. Cover crop was highest in microbial abundances in the greenhouse and amendment was highest in the field. Herbicide led to increased soil nitrate and low labile carbon, but this was offset by cover crop addition.