N Cycling Team

Diagram describing relationship between cover crop properties and N cycling.
Photo credit: L. Canisares.

Observation

Corn and cotton are both fertilized with high rates of nitrogen (N) fertilizer, a portion of which can be lost to the environment. These losses contribute to greenhouse gas emissions and impaired water quality. Precise management of N inputs is an important component of Precision Sustainable Agriculture. Previous research suggests that cover crops can increase or decrease N fertilizer needs for the subsequent crop, depending on the cover crop species and production environment. However, we do not have sufficient data to recommend N fertilizer rate adjustments for corn and cotton following dominant cereal and legume cover crops in different regions of the U.S. The PSA partners who participate in our common experiment-1 (CE-1) protocols will work to identify the synchrony between N fertilizer inputs and crop uptake to reduce the agronomic optimum N rate.

Approach

Cover crops use excess nitrogen (N) in a system to fuel their growth, which prevents N from leaching into the environment. Legume cover crops have the additional benefit of fixing bioavailable N through root nodules. This N is then released from cover crops during decomposition and made available throughout the growing season to the following cash crop. Partners executing the CE-1 protocol will conduct a field-based experiment for 3 years in 15 different sites including the northern (IN, NE, NY, PA, VT and WI), middle (IL, KY, NC, MD, DE and KS) and southern (SC, LA and FL) U.S.

Data Collection

This study will seek to determine how cover crop parameters (e.g., chemical composition, N fixation, biomass production), soil properties (e.g., texture, soil organic C%), and weather (e.g., spring precipitation) interact to influence the optimum N fertilizer rate for corn and cotton following cereal, legume, and mixed cover crops. The results provided by this collaborative experiment will provide data to support farmer decision-making for site-specific cover crop and N management.