What we're doing

Our research is designed to improve our understanding of how plant-soil interactions influence nutrient cycling and availability in organic and limited-resource cropping systems, with an emphasis on the rhizobia-legume symbiosis.

A multi-regional approach for sustained soil health in organic high tunnels

Grant Cycle: 2016-2020

preparing high tunnel for cultivationSeason-extending high tunnel production has been expanding rapidly across the U.S., offering organic growers an exciting new option for production.  High-tunnel production is characterized by increased productivity, but due to intense cultivation strategies, high tunnels pose many challenges for sustainability, soil health, and environmental quality. The long term goal for this integrated project (Research, Education) is to develop a comprehensive and economically viable model to address soil health issues in high tunnels across a North-South range (with tunnels in MN-KS-KY), resulting in increased adoption of practices such as legume cover crop incorporation that promotes sustainable management of organic high tunnels and financial stability for farmers. In this project we are evaluating a range of farmer-selected rotations in these three distinct regions, building a predictive understanding of soil quality management and economics of season extension, and facilitating knowledge exchange with a focused emphasis on limited-resource farmers and historically underrepresented groups. 

This project is led by the Grossman lab and is a multi-state collaboration between Drs. Krista Jacobson at the University of Kentucky, Cary Rivard at Kansas State University, and Jessica Gutknecht and Hikaru Peterson at the University of Minnesota. It is supported by a USDA Organic Research and Extension Initiative (OREI) grant. ($1,5 Million).

Building Hmong Farmers’ Capacity and Self-efficacy To Tackle Soil Fertility Issues

Field day participants Rosemount MN 2017

Grant cycle: 2018-2019

Hmong farmers provide much of the locally grown fresh produce in the Twin Cities, yet often work on low fertility soils due to limited land tenure possibilities. Cover crops are useful alternatives to costly synthetic fertilizer options, and additionally provide a multitude of environmental benefits.  The goal of this project is to examine the effect of three modified zone till systems at the Hmong American Farming Association (HAFA) Farm on soil health and productivity. The project includes many education activities as well, including field days and farm tours for local Hmong youth. We expect results will increase Hmong farmers’ confidence in and ability to use legumes in zone tilled cropping systems for intensive vegetable production.

This project is a collaboration with the Hmong American Farming Association (HAFA) and is generously supported by a Healthy Foods Healthy Lives Community-University Partership Grant ($49,913).

Summer Cover-Cropping Strategies and Organic Vegetable Production for Beginning, Immigrant Farmers

MDA immigrant farmer grant Vivian in field

Grant cycle: 2016-2019

Farmers in the USA are becoming a more diverse population, especially those in vegetable production. Immigrant and minority farmers often face particular challenges of land tenure and soil quality due to legacies of inequity, which exacerbates their struggles with the challenge that all farmers have of how to manage tradeoffs that balance crop production with ecological sustainability. The Upper Midwest growing season for vegetables, many of which are not frost-tolerant, is fairly short, so much of the regionally-focused work on cover crops concerned those grown during the non-vegetable growing season. However, vegetable farmers often grow many different vegetables, some of which are planted and harvesting during the spring and fall, leaving bare, unused soil during the summer. Cover crops grown during this bare period could provide benefits to soil structure and nutrient status, inhibit weed growth during the long, hot days of summer, and protect soil from intense summer storms that are typical in the Upper Midwest. This farmer-driven project investigates the role that summer cover crops can play in enhancement of soil nutrients and overall health when grown for short periods of time.

This project is generously supported by the Minnesota Department of Agriculture (MDA) Specialty Crop Block Grant ($99,974).

Soil health and nutrient management training for immigrant and minority farming communities

Immigrant and minority farming communities

Photo credit: Shared Ground Farmer Cooperative

Grant cycle: 2015-2017

Immigrant farmers represent a growing population of food producers in Minnesota and elsewhere in the Upper Midwest. Feedback from these farmers demonstrates interest in learning how to calculate nutrient rates for organic crops, as well as manage inputs such as cover crops and organic fertilizers. Currently, there is no comprehensive resource for soil management training for either immigrant farming organization educators or farmers. This project will develop hands-on courses and online resources to teach soil and nutrient management to diverse audiences, with an emphasis on immigrant farmers. Soil science topics will include cover crops, nutrient management for small fruit and vegetable crops, signs of nutrient stress, soil test interpretation, irrigation/fertigation system design and operation, season extension, and tillage equipment operation and maintenance. We will partner with The Good Acre NGO, serving as a food hub to immigrant and low-resource farmers, to deliver experiential, on-site training to 40 agriculture leaders who work with immigrant farmers, including extension educators, NRCS personnel and immigrant farmer leaders. 

This project is funded through the Sustainable Agriculture Research and Education Professional Development Program (SARE-PDP; $74,760)

Bringing the benefits of legume cover cropping to northern Midwest climates

Vetch nodule

Grant cycle: 2014-2018

The purpose of this project is to provide legume cover crop options to growers in the upper Midwest by examining the key  microbial process of nitrogen fixation that regulates nitrogen (N) cycling in select winter-hardy legumes, and by designing an innovative set of educational tools showcasing exemplary farmers who successfully utilize legume cover crops in colder climates, or face challenges in doing so.  In particular we will investigate the need for legumes to be inoculated in midwestern soils that may already have competitive rhizobia strains present. Competitive indigenous populations of rhizobia present in farm soils have been shown in many regions to impact the success of rhizobia inoculants added at legume planting. Since rhizobia are present in almost all soils, we hypothesize that legumes may form relationships with indigenous rhizobia that may affect nitrogen fixation rates, either increasing or decreasing its performance.  We will develop a replicated field experiment assessing five legume cover crop species or mixes, and three inoculation treatments to determine if inoculation provides plant growth benefits to legume cover crops in Minnesota soils.

This project is a NC-SARE funded proejct ($114,000).

Understanding rhizobia ecology in legume cover crops

Year: Ongoing

BOXBiological nitrogen fixation (BNF) is the major source of new nitrogen in organic agriculture, yet there has been almost no research devoted to understanding how organic management practices impact this process. Furthermore, few widely used, temperate green manures have been characterized in terms of their nitrogen fixing traits and the ecology of the bacteria responsible for legume BNF, called rhizobia. The goal of this project is to improve understanding of biological nitrogen fixation and rhizobia ecology within organic cropping systems so that this process can be most effectively managed. We are using molecular techniques to ‘fingerprint’ and genetically characterize rhizobia strains that have been both extracted from nodules of legume cover crops and ‘trapped’ from NC farm soils. We are interested in how history of organic management affects the efficiency of rhizobia inoculants, commonly used when farmers plant legume cover crops. We hope that our research will show us how specific management practices are impacting the ecology of rhizobia found in symbiosis with commonly grown legumes in organic systems.