Using a combination of field and greenhouse methods incorporating stable isotope tracing, this work aims to directly link crop cultivars, rhizodeposition, microbial activity, and nitrogen cycling. Our results may help inform breeding and farm management decisions, especially in soils without chemical fertilizers.

Soil organisms can improve soil aeration and water flow, as well as prey on crops pests and contribute to the maintenance of soil biodiversity. In collaboration with researchers at UC Davis, UC Berkeley, and California State, Fresno, we explored the effects of cover crops and reduced tillage on soil macroinvertebrates, and their relationship to soil health. Total species abundance increased 93% in rotations with winter cover crops, and 50% with no tillage. You can access the article here.

Cover crops have been shown to improve many aspects of soil health; however, dryland farming poses an extra challenge as crops compete for limited water. In collaboration with grain and cattle producers across Colorado, Kansas and Nebraska, our multi-institution team assessed the soil health and economic implications of short-term grazed cover crops. You can access the NRCS webinar presenting our findings here and find the one-page graphical summary here. Additional project information and related research in dryland agriculture can be found atdrylandag.org. The resulting article from this study is available here.

Can large soil organisms improve water capture in semi-arid croplands? Utilizing an long-term 32-year crop rotation study at multiple locations in eastern CO, USA, we measured soil macroinvertebrate populations and water infiltration metrics. We found marginal increases in soil invertebrate populations with less frequent bare soil, but even continuous cropping did not compare to the robust perennial grassland. Read the short magazine summary here and the full scientific publication here.

This project is in collaboration with the Aspen Center of Environmental Studies organic farm at Rock Bottom Ranch. We are evaluating the soil health impact of their complex grazing rotation system through a multi-year controlled experiment. Final field sampling in Fall 2021 will give us important data on the success of this unique grazing practice.

Utilizing meta-analysis techniques, we are exploring the effect of different soil amendment types on soil carbon formation into different soil fractions with different levels of stability. This work builds on the long-term agricultural research projects located across the globe and is an on-going project in collaboration with Erika Foster. The database created for this project is accessible here.