Managing Soil Biology to Increase the Sustainability of Conventional Farming Systems: Learning from Long Term Experiments.

Can the sustainability of conventionally managed cropping systems be increased by enhancing soil biology? Organic cropping systems commonly employ cover crops, legumes, livestock manure, and organic fertilizers; many of these practices increase soil biological activity and biodiversity. These practices not only increase the abundance and diversity of soil microbial communities, but can alter functional properties and promote creation of physical microenvironments supporting diverse microbial processes. Enhancing soil biological processes can increase agricultural sustainability by offsetting fossil-fuel based inputs of fertilizers and pesticides.

In the 20th year of the Century Experiment at the Russell Ranch Sustainable Agriculture Facility, UC Davis, we compare organic and conventional two year tomato-corn rotations, as well as a hybrid farming system that incorporates both conventional and organic practices. Sustainability is measured via long-term trends in yield, profitability, resource-use efficiency (such as water or energy), below ground biodiversity and environmental impacts.  The soil microbial community composition has diverged among the systems and inputs of compost and cover crops have led to higher soil microbial biomass.