Improving Accuracy of Nutrient Removal Estimates

The overall objective of this project is to produce credible nutrient removal coefficients with a stated margin of error at spatial resolutions appropriate for a variety of common uses. This overall objective will be accomplished in two phases 1) a short-term phase (June 2011) and 2) a long-term phase (on-going).


Objectives

The specific objectives of Phase 1 are as follows:

1. Gather readily-available individual observations (raw data) of nutrient concentrations in corn, soybean, winter wheat, and spring wheat grain
2. Assemble these grain concentration data into a Microsoft Excel workbook as tables
3. Calculate nutrient removal coefficients in units of lb nutrient per bushel
4. Select appropriate statistics for central tendency and margin of error
5. Create a summary table for each crop that shows for each combination of nutrient and state:
1. The central tendency of the collected data
2. The margin of error of the collected data
3. National/regional feed data
4. The published nutrient removal coefficient currently used by the Extension Service in that state
6. Identify metadata that are required to properly characterize nutrient concentration data (i.e. sample preparation techniques, digestion methods, and detection instruments)

The objectives of Phase 2 are as follows:

1. Use Phase 1 to determine the feasibility of creating a shared, dynamic database that a community of interested people contribute to over time
2. Use Phase 1 to develop a database structure for storing raw nutrient concentration data for grain (either privately held or publicly available, based on objective 1)
3. Extend Phase 1 methods and database development to other crops:
1. more grain/oilseed crops
2. forage crops
3. specialty crops
4. Extend Phase 1 methods and database development to other data types:
1. Summarized data
2. Crop quality surveys
3. Councils
5. Create criteria for determining when a currently used removal coefficient should be adjusted

Methodology

Dr. Nathan will gather data for state-level assessments by contacting faculty working in the areas of soil fertility/nutrient management in both the North Central (NCERA-13) and Southern Regional Groups (SERA-IEG 6). The data requested will be grain nutrient concentration data for corn, soybean, winter wheat, and spring wheat. Data are expected to come from samples collected from farmer fields, research plots, State Dept. of Agriculture Grain Inspection Service Centers, grain elevators, and if possible, private laboratories. States to be contacted include MO, KS, IA, IN, IL, MN, NE, OH, SD, ND, OK, AR, KY, TN, AL, GA, LA and TX. Data will be input into Microsoft Excel spreadsheets to start building the statewide nutrient removal tables. Central tendency and margin of error statistics will be selected, and the data summarized into a table that compares, for each crop and state, the observed data with the nutrient removal coefficients currently used in each state.