Creating Climate Resilient Organic Systems by Enhancing Arbuscular Mycorrhizal Fungi Associations

While the majority of carrots are cultivated in California, recent droughts and water use restrictions may impact the success of future crops. Even in states such as Wisconsin, where water is more abundant, crops still must overcome oscillating soil moisture regimes due to differences in soil drainage, water-holding capacity, and microclimate conditions, as well as the anticipated drier summers which are predicted to increase with climate change.

Additionally, organic vegetable crops, especially in newly organic land where soil-building may not have yet been optimized, can be challenged by more slowly available soil nutrients. Symbiotic microbes such as arbuscular mycorrhizal fungi (AMF) increase plants’ access to vital nutrients like nitrogen (N) and phosphorus (P) as well as water, contributing improved crop yields and soil health. Although the importance of this association is widely understood, it is unknown whether different cultivars of a single crop differentially stimulate AMF populations.

We propose to study this cultivar-AMF interaction on working organic farms, evaluating the contribution to carrot growth as well as the contribution of potential cultivar-symbiont selectivity on AMF populations in a variety of soil types across organic farms in Wisconsin. Using replicated trials on the certified organic land at the University of Wisconsin West Madison Agricultural Research Station in combination with the working certified organic farms, we will correlate weather and soil variables and cultivar selection with detailed characterization of soil microbial profiles, with a specific focus on AMF. Results will be communicated at field days, farmer workshops, and conferences, and video and written results housed on appropriate UW websites.

Recommendations will focus on cultivar selection and crop rotation to build beneficial soil fungal communities. These best practices will also help buffer organic producers from perils of drought and flood, as healthy plants and thriving mycorrhizal networks enhance crop tolerance to stressful conditions.