The rising temperatures and changing rain patterns associated with climate change have created an urgent need to increase resiliency in our crop production systems. Organic Farming Research Foundation (OFRF) provided a research grant to Dr Erin Silva in the Department of Plant Pathology at the University of Wisconsin – Madison (UW-Madison) to examine the ability of Arbuscular Mycorrhizal Fungi (AMF) to enhance soil moisture retention and increase access to nutrients.
An important aim of organic production is to improve overall soil health. AMF form symbiotic relationships with the roots of host plants through which plants receive nutrients. AMF also indirectly promote plant health through their contribution to soil building. Thriving AMF communities increase the water-holding capacity of soils through the deposition of proteins. This project sought to determine whether the genetic variances between popular cultivars of carrot would promote the growth of different AMF communities over the growing season and alter the quantity of AMF-associated proteins in soils.
The researchers evaluated the role of carrot cultivar on AMF-related proteins, an important factor influencing soil health improvements related to AMF communities. The project was done in collaboration with six organic farmer members of the Fairshare Community Supported Agriculture (CSA) Coalition in Wisconsin during the 2017 and 2018 field seasons.
Silva’s recently submitted final report shows that while there were no obvious trends toward increases in AMF-associated soil proteins that correlated to any cultivar of carrot, most sites had moderate changes in protein quantities from spring to fall (with no clear pattern). One site had consistently increased fall quantities of AMF-associated proteins compared to spring quantities for all cultivars for both years (2017 and 2018). The research team also observed more intensive weed management at this site. Storm-related flooding impacted some farms during the project, causing considerable losses at multiple sites.
According to the research team, the project provided important preliminary data in two areas that warrant further research. First, particularly among open-pollinated cultivars, it would be beneficial to screen diverse genotypes for enhanced AMF colonisation, to be used either directly by farmers or included in breeding programs. Second, preliminary data shows some interesting interactions in the role of AMF in increasing soil proteins, with their role in enhanced soil aggregation in highly disturbed environments. The team suggests it be valuable to further investigate the role of cultivar selection and AMF inoculation on soil aggregation in heavily tilled/cultivated phases of the organic crop rotation, and in intensive vegetable production.
Outreach included reports to the farmer cooperators, as well as presentations at organic vegetable field days. As a follow up to this work, the researchers aim to use sequencing technology to identify the AMF community constituents present in samples obtained during this project. This data may be used to correlate species or genus abundance with soil protein quantities to identify whether specific communities contribute to greater protein deposits in agricultural soils.
