IS THERE A ROLE FOR MICROBIAL MANAGEMENT IN ORGANIC AGRICULTURE?

many organic farmers understand that soil microorganisms are important for soil function, but are unsure how to effectively manage microbial populations. soil microorganisms are increasingly important as farmers transition to organic agriculture, as microbial services need to replace benefits that would otherwise have been provided by chemical inputs. for example, microorganisms can transform nutrients from forms that are unavailable to plants to forms that are available to plants, which limits the need for fertilizer additions.attempts to directly manage microorganisms are common in organic agriculture. popular approaches include the development of compost that is expected to contain beneficial microorganisms, korean natural farming, and the application of live microbial products obtained commercially. this latter approach in particular is growing in popularity. for example, a substantial majority of organic farmers in ohio used microbial products in 2014, which was more than twice the proportion measured in 2009.however, microbial communities are incredibly diverse and complex, and to the farmer, invisible. this invisibility makes it hard for farmers to benchmark potential solutions, leaving them without a real framework for microbial management, and thus, no clear consensus on which approaches to apply. in this project, we will examine how soil type and farming practices interact with both passive and active microbial management, in collaboration with farmer partners, and within a long-term organic farming project at penn state.our research objectives are to:1) determine how location, existing management, and microbial re-seeding impact microbial colonization of soils. this will help farmers to understand the impact of including diverse plants in or around production areas on microbial diversity, and will also validate the impact of additional management treatments that they are using.2) link the establishment of omri-certified microbial products to soil traits, and determine whether on-farm conditioning can enhance product survival. microbial products have a long history of unpredictable effectiveness, and we aim to advance understanding of where products will be effective and why.3) evaluate the sensitivity of soil respiration, a widely used metric for microbial health, to microbial composition. many organic farmers pay to assess soil respiration, with the assumption that it reflects soil biological health; however, respiration readings are confounded by differences in soil characteristics. we aim to determine how sensitive this assay is to microbiological differences, and benchmark this against two other potential metrics of soil biological activity.our extension objectives are to work with farmers to understand the role of soil microorganisms in organic agriculture through annual meetings and farmer conferences, and make lasting contributions to their decision-making through extension publications that communicate our results and reveal the breadth of microbial management used by organic farmers.we believe that providing empirical guidance on microbial management is going to help organic and transitioning farmers assess the risks and rewards of investing in this area.