Getting to the Root of the Matter: Linking Root Traits to Soil Health

Soil organic matter (SOM) contains large stocks of C and N, represents a major source and sink of atmospheric greenhouse gases, and plays a key role in soil health and fertility. Because SOM content is positively associated with crop yield and yield stability, increasing SOM can benefit farmer income, food security, and resource use efficiency while providing ecosystem services like C sequestration. Most of the organic matter in soil is derived from roots, yet it is unclear how root architectural and chemical traits regulate the formation and stability of SOM. This proposal will advance our understanding of crop root system impacts on SOM. Our objectives are to: 1) quantify variation in root traits relevant to SOM storage among a diverse panel of maize cultivars, 2) determine how variation in belowground traits impact SOM stocks, and 3) determine the interactive effects of root characteristics and soil properties on the formation and stability of SOM. Using a diverse panel of 18 open-pollinated varieties and hybrids grown in the greenhouse, we propose to measure changes in exudate production, root architectural traits, and chemical composition due to breeding over the last ~100 years. We will select four hybrids with distinct root systems from this panel for a field study that will test the effects of hybrid, plant density, and aboveground residue removal on SOM storage using natural abundance 13C tracing. Lastly, we will perform a laboratory incubation study to investigate the effects of root chemical composition on the efficiency of SOM stabilization in different soil types. Through this research, we expect to identify root traits that promote the formation and stability of SOM.