Soil Ecology Research Laboratory

Re-coupling carbon and nitrogen cycling to increase nutrient use efficiency in annual cropping systems

Project summary:

A significant amount of research in terrestrial ecosystems has focused on the interplay between carbon (C) and nitrogen (N) cycles. Understanding of these interactions is crucial if we are to fully comprehend the role of managed ecosystems in regulating global biogeochemical cycles. This is particularly important in the case of intensively managed annual cropping systems where 40-50% of the N applied is lost to the environment. The goal of the proposed research is to investigate the relationship between management practices that control the quantity and quality of C inputs, labile soil organic matter pools, microbial community function and N retention. Our central hypothesis is that the linkages between N and C can be intentionally managed to optimize N retention and reduce N losses from agroecosystems. Although we emphasize the relationship between carbon (C) and nitrogen (N) cycling in framing our questions, we include exploratory research aimed at investigating the influence of C flow on P balances and organic P pools.The research will be conducted on commercial farms ranging from corn monocultures to more complex grain-production systems with diversified rotations and organic N inputs. Three years of work are proposed, however our intention is to maintain these sites for 10-15 years and to make them available to other investigators once they are established

Objectives:

1. We will construct input-output nutrient budgets for the major nutrients that cycle with C as well as estimate total C inputs on 20 commercial farms.
2. We will determine the effects of management on SOC composition, organic N and P pools and microbial community structure and function on 12 of these farms.
3. We will use 15N to conduct detailed assessments of the internal cycling and retention of N on six of our farm sites.

Project staff:

Principal Investigator: Laurie E. Drinkwater, Cornell University
Co-Investigator: Janice E. Thies, Cornell University