2007 Annual Report 1a.Objectives (from AD-416) Objective 1: Determine the role of spatial variability in affecting management outcomes in dryland and irrigated systems. a. Develop sensors for in-season nutrient management. b. Determine management zones for efficient use of inputs. c. Residue management to maintain or enhance critical soil functions. Objective 2: Improve understanding of N and C dynamics in cropping and tillage systems commonly used in the Western Corn Belt and Central Great Plains. a. N index - Assist NRCS efforts to develop a N index for identifying BMP's that minimize N losses in runoff and leaching. b. Develop an algorithm for in-season N management. c. Soil C dynamics to enhance C sequestration. Objective 3: Implement and expand the Soil Management Assessment Framework (SMAF) a. Develop additional scoring curves for the SMAF. b. Implement the SMAF. Objective 4: Determine the impact residue removal for biofuel production has on the soil resource. 1b.Approach (from AD-416) Objective 1 a. A network of field sites managed by ARS and University scientists will collect common types of data on corn and wheat receiving different rates and timings of N fertilizer. Guidelines and algorithms for producer use of sensors will be developed. b. Apparent electrical conductivity, aerial photography, and yield maps will be assessed for their potential in delineating spatial variability in soil properties that affect plant productivity, nutrient availability, and water status. c. Experiments with factors including tillage, crop sequence, nitrogen fertilizer application, and residue removal are being conducted under contrasting environments (dryland and irrigated); measures of biomass production, grain yield, N removal, change in soil organic carbon, and soil quality indicators will be used to estimate the impact of residue amount and placement on productivity and soil function. Objective 2 a. A team of ARS and University experts will evaluate existing models, develop a strategy, and build an N-Index based on documented requirements, intended delivery method, and applications described by NRCS. b. Chlorophyll meter and grain yield data from a long-term field experiment comparing irrigated cropping systems (continuous corn and corn-soybean rotation), corn hybrids, and N fertilizer rates conducted at the Nebraska Management Systems Evaluation Area (MSEA) will be integrated to develop the algorithm. c. Data on biomass production, grain yield, and change in soil organic carbon with time from an existing experiment with treatment factors of tillage and crop sequence will be used to estimate the impact of residue source and placement on productivity and soil function. Objective 3 a. Soil indicators have been identified and a protocol for creating scoring curves has been developed for use in expanding the SMAF. b.Studies measuring soil properties under various management practices will be identified and evaluated using the SMAF. Objective 4 Two experiments, one including factors of tillage and crop residue removal conducted under irrigation and a second with factors of crop (corn or switchgrass) and residue removal under rainfed conditions have been established. Data from this study and those of other CLEAR CRIS participating locations will be combined to create recommendations for residue retention based on cropping system, climate, and production level. 4.Accomplishments Title: Crop residue requirements for sustainable soil management. Problem: The amount of crop residue needed to sustain soil quality following biomass harvest for off-farm use is not known. Accomplishment: Factors affecting availability of stover for use as a biomass feedstock for ethanol production and the stover requirements for maintenance of soil organic C have been identified providing NRCS with information needed to produce technical notes for conservation practices used by producers harvesting crop residue for off-farm use. Impact: Appropriate conservation practices will be implemented on fields where crop residue is removed for off-farm use. This accomplishment addresses National Program 202 Soil Resource Management Problem Area 6: Impact on Soil of Residue Removal for Biofuel Production [Renewable Energy Assessment Project (REAP)] 5.Significant Activities that Support Special Target Populations None 6.Technology Transfer Number of non-peer reviewed presentations and proceedings 14 Number of newspaper articles and other presentations for non-science audiences 24 Review Publications Wienhold, B.J. 2007. Comparison of laboratory methods and an in situ method for estimating N-mineralization in an irrigated silt-loam soil. Communications in Soil Science and Plant Analysis 38:1721-1732. Grigera, M.S., Drijber, R., Wienhold, B.J. 2007. Redistribution of crop residues during row cultivation creates a biologically enhanced environment for soil microorganisms. Soil & Tillage Research. 94:550-554. Hoskinson, R., Karlen, D.L., Birrell, S.J., Radtke, C.W., Wilhelm, W.W. 2006. Engineering, nutrient removal, and feedstock conversion evaluations of four corn stover harvest scenarios. Biomass and Bioenergy. 31(2-3): 126-136. Available: http://www.sciencedirect.com/science? Johnson, J.M., Coleman, M.D., Gesch, R.W., Jaradat, A.A., Mitchell, R., Reicosky, D.C., Wilhelm, W.W. 2007. Biomass-bioenergy crops in the United States: A changing paradigm. The Americas Journal of Plant Science and Biotechnology. 1(1):1-28.