Start Date: Oct 01, 2006
End Date: Sep 30, 2011
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.