Project Number: 3640-12000-007-00
Project Type: Appropriated

Start Date: Mar 25, 2006
End Date: Mar 24, 2011

Objective:
Quantify the impact of agricultural practices and environmental changes on surface/atmosphere exchange of greenhouse gases (GHG) in order to develop farming systems that reduce global warming potential (GWP) and promote soil C sequestration; Develop farming systems that permit the removal of biomass for energy production while protecting soil resources; Identify and overcome agronomic impediments to the adoption of farming practices, such as reduced tillage, cover crops, and companion crops, that are developed to reduce GWP and permit stover harvest.

Approach:
We will participate in a multi-location effort to identify farming practices that will help slow the increase in atmospheric concentrations of the greenhouse gases CO2, N2O, and CCH4. Our approach will include continuous, field-scale measurement of the surface/atmosphere exchange of all three gases in three adjacent fields under different management. Parallel plot-scale studies will be conducted with chamber-based gas exchange measurements to permit testing of a broader variety of tillage, nitrogen (N) fertility, and rotation strategies. In the second principal area of inquiry, we, again in cooperation with other ARS locations, will examine the soil sustainability of harvesting corn stover for ethanol production. Our goal is to test the hypothesis that cover or companion crops can fill the role of the removed stover in supplying carbon (C) compounds to maintain soil organic matter. We will explore the use of forage digestibility analyses to characterize the quality and quantity of C compounds contained in corn stover and in cereal rye, kura clover, and selected other cover crops. The third component of this project will focus on identifying and correcting practical, agronomic impediments to adoption of the practices mentioned above. In the upper Midwest, the major hindrance to wider use of cover crops, companion crops, and reduced tillage has been the perception that they will reduce the yield of the subsequent crop, due to such factors as cold, compacted spring seed bed conditions and adverse effects on N availability. We will test and refine theories describing near-surface heat and water flow and develop sensors to more easily measure soil bulk density. We will also conduct plot-scale studies of the effects of reduced tillage and cover crops on N losses by leaching and gaseous emissions. The results of this research will facilitate the development of better reduced tillage and cover crop systems for northern soils.