2011 Annual Report 1a.Objectives (from AD-416) Determine the amount of corn stover residue needed to maintain soil C content (soil quality) and crop productivity. 1b.Approach (from AD-416) The core, multi-location field experiment will include replicated plots established on a highly productive soil series using no tillage continuous corn and no tillage corn/soybean with rye cover crop rotation following standard agronomic management practices. The corn stover harvest treatments will consist of 0, ~50, and maximum possible residue removal. Corn will be grown using standard commercial practices including pre-emergence herbicides, NPK fertilization and insecticides as necessary. Soybeans will be grown using standard no-till commercial practices with post-emergent herbicides and insecticides as necessary. 3.Progress Report This multi-location project consists of both University and USDA-ARS collaborators at each site. The goal of the project is to determine the amount of corn stover residue needed to maintain soil C content (soil quality) and crop productivity. Cooperators are each responsible for managing the site within their region. Overall progress of the multi-location project was monitored through an annual meeting in Ames IA in March with the University Park progress monitored through periodic meetings, conference calls, site visits, and emails with University collaborator. We successfully established our main feedstock experiment, consisting of five rotation treatments. 1)continuous corn,. 2)continuous corn with rye cover crop,. 3)corn/soybean with rye cover crop,. 4)soybean/corn with rye cover crop, and. 5)continuous corn planted in twin rows with a higher plant population. For each these rotation treatments, there are three stover removal rates, 0, 50% and 100%. A summary of 2010 crop grain yield, corn stover biomass harvested, and nutrient analysis of corn grain and stover was completed