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Nutrient Budgets For CNMPs. Nutrient Management Planners Training March 31, 2009 Bobby Smith County Extension Coordinator UGA Cooperative Extension Morgan County. Animal manures used for centuries as fertilizer. Benefits: micronutrients slow release of N an P SOM
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Nutrient Budgets For CNMPs Nutrient Management Planners Training March 31, 2009 Bobby Smith County Extension Coordinator UGA Cooperative Extension Morgan County
Animal manures used for centuries as fertilizer Benefits: micronutrients slow release of N an P SOM soil structure CEC carbon sink (global warming)
Nutrients in organic form N P K is not in same proportion that crops need – usually 1-2-2 instead of 3-2-1.
Balancing Manure nutrient inputs Crop needs
Nutrient Budgets • N-based budgets • Minimize NO3 leaching • Manures supply more P than crops need • Excess P leads to eutrophication • Will have P-based budgets • Determine priority nutrient
Nutrient Budgets • Two methods • Spreadsheets – QuattroPro & Excel • Ag Pollution Prevention page • http//www.agp2.org • Nutrient Management Planning in Georgia • CNMP Tools • Worksheet • In notebook
Nutrient Budgets Both methods are Field Scale • Calculate budgets for each field and sum for farm • Proper rate for each field • Simulate different scenarios
Three Steps • Determine crop needs • Determine nutrients supplied • Balance
Crop Needs • Need crops to use nutrients • Crops have to fit in production system • Crops needs vary • Table in Notebook • Crop recommendations • Based on SOIL TEST • Maintain nutrient balance • Maintain pH
Nutrients Available from Manure • Nutrients in organic form • Not all available to plants • Nitrogen • Mineralization • Waste characteristics, temperature, moisture • Losses to volatilization • pH, temperature, how applied
Nutrients Available from Manure • Definitions Total N = Organic N + NO3 + NH4 Plant available N % Organic N + NO3 + NH4 TKN (Total Kjeldalh N) Organic N + NH4
Example – Fresh Dairy Manure (wet basis) TKN = 10.4 lbs/ton NH4 = 1.9 lbs/ton NO3 = 0.03 lbs/ton What is Total N? TKN + NO3 = 10.4 lbs/ton What is PAN? (%mineralized*(TKN-NH4)) + NH4 + NO3 = 2.6 + 1.9 +0.03 = 4.53 lbs/ton
Nutrients Available • UGA manure test results give total nutrients • Determine Plant Available Nutrients • Use Availability Coefficients • Depends on manure and application method • Incorporates losses through volatilization and form of nutrient
Nutrients Available • UGA lab reports on wet basis • Dry basis need % solids • To use spreadsheet need results • Wet basis • Total N, P2O5, K2O
Balancing Needs Go to Spreadsheet
Summary • Manure • Improves Soil Organic Matter • Improves Soil Structure • Increases Cation Exchange Capacity • Provides Micronutrients • Not all nutrients are available to plants Manure is not in the correct ratio for crop use (usually 1-2-2 instead of 3-2-1)
Summary Continued • Nutrient Budgeting is balancing manure nutrients supplied with crop needs • Nutrient Budgets are field scale • Availability coefficients according to manure application and storage method determine percent available
AGRICULTURAL POLLUTION PREVENTION PROGRAM Sponsored by the GA Pollution Prevention Assistance Division-AgP2 Bobby Smith- rcsmith@uga.edu UGA Cooperative Extension Biological & Agricultural Engineering Dept. College of Agricultural & Environmental Sciences University of Georgia