Nutrient Budgets For CNMPs Nutrient Management Planners Training

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 NO 3 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 – Quattro. Pro & Excel • Ag Pollution Prevention page • http//www. agp 2. 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 p. H

Nutrients Available from Manure • Nutrients in organic form • Not all available to plants • Nitrogen – Mineralization • Waste characteristics, temperature, moisture – Losses to volatilization • p. H, temperature, how applied

Nutrients Available from Manure • Definitions Total N = Organic N + NO 3 + NH 4 Plant available N % Organic N + NO 3 + NH 4 TKN (Total Kjeldalh N) Organic N + NH 4

Example – Fresh Dairy Manure (wet basis) TKN = 10. 4 lbs/ton NH 4 = 1. 9 lbs/ton NO 3 = 0. 03 lbs/ton What is Total N? TKN + NO 3 = 10. 4 lbs/ton What is PAN? (%mineralized*(TKN-NH 4)) + NH 4 + NO 3 = 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, P 2 O 5, K 2 O

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. Ag. P 2 Bobby Smith- [email protected] edu UGA Cooperative Extension Biological & Agricultural Engineering Dept. College of Agricultural & Environmental Sciences University of Georgia