Balancing Manure Nutrient Inputs and Outputs BILL PAN AND HAIYING TAO DEPT CROP AND SOIL SCIENCES WASHINGTON STATE UNIVERSITY

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1 Balancing Manure Nutrient Inputs and Outputs BILL PAN AND HAIYING TAO DEPT CROP AND SOIL SCIENCES WASHINGTON STATE UNIVERSITY 2015 WA STATE AG STATISTICS Commodity $ value sold AG products %U.S. PRODUCTION US STATE RANK Apples Milk Wheat All WA Ag 9.1 NASS.USDA.GOV Dairy Farm Nutrient Balance MNB Hermanson et al., Other farms, energy Law of Mass Conservation Farm Nutrient Balance Mass can neither be created nor destroyed, although it may be rearranged in space, or it may be changed in form Mikhail Lomonosov, 1756 When the inflow of nutrients is greater than the outflow, nutrient losses and/or soil accumulation will occur farm nutrient balance 1

2 Three Scenarios County Scale Nutrient Balance (harvest removal/use) County N P 2 O 5 K 2 O Yakima Grant Whitman *IPNI, doesn t account for milk and manure exports in harvest removal Balancing Nutrients in Land Application Needed Input Information Manure testing or use standard values Soil test Other fertilizers Irrigation water Nutrient release from previous manure applications Balancing Nutrients in Land Application Outputs Crop removal: harvest wt x nutrient concentration Estimate of soil organic matter and nutrient buildup rate Excess nutrients escape into the environment Raw Manure? Example lagoon analysis, after solids separation 2

3 Compost NH 3 gas Estimating Organic N Inputs Organic Fertilizer Components: Ammonium N 70 Organic N 30 NH 4 NO 3 mineralized N remaining org. N Crop N Accumulation Uptake Efficiency Plant Available N Other Sources: 1. Soil OM mineralization 2.Carryover NO3, NH4 3.Legume or straw mineralization or immobilization 4. N in water 5. Nmin from previous organic amendments 6. Other fertilizers Percent of NH 4 -N lost after manure application Incorporated days after surface application Injection immediate 1 day 2 days 1 week No incorporation % Dairy lagoon water Dairy lagoon slurry thin Dairy lagoon sludge thick Solid dairy manure Separated solid Aerobically composted dairy manure Plant available N (PAN) from manure Manure type % of organic N mineralized to PAN Dry This Year 2 Year 3 Year 4 Years 5-9 matter season % %/year - Dairy lagoon water <1% Dairy lagoon slurry thin 1-5% Dairy lagoon sludge thick 5-10% Solid dairy manure >10% Mechanically separated dairy solids Aerobically composted dairy manure Know crop nutrient requirements, e.g. silage corn pnw0615 Alfalfa pnw0611 3

4 Manure Slurry Managing Organic Fertilizers: similar principles Biosolids Organic Amendments Feed Plants & Soil *Seattle biosolids doubled soil C and N in 20 yrs applied every 4 years to wheat fallow in Okanogan. *The buildup of the stable fraction could have originated in the biosolids. *No other fertilizer was required to produce equal grain. Compost MANURE INCREASES SOIL ORGANIC MATTTER Reactive OM: food for microbes Stable OM: won t readily breakdown *This path wasn t in our 95 MNB model Potential increase in water holding capacity with increased soil organic matter Assumes increase occurs in top 6 of soil Additional USDA resource: FSE_DOCUMENTS/nrcs142p2_ pdf Water Holding Capacity=Field Capacity Permanent Wilting Point Table 2.6. Range of water holding capacity for different soil textures N mineralization in soils e= &topicorder=10&maxto=10 4

5 N mineralization in soils collected in Yakima Valley Crop rotation: alfalfa-alfalfa-alfalfa-corn Sample date: May 2016 Sample size: 102 soil cores from 34 sites Manure type: 7 fields applied with separated dairy liquid 17 fields applied with composted dairy solid 10 adjacent uncultivated soils with no manure application. Mineralization Lab Study Collecting soil cores Dairy manure applications increased soil organic matter (SOM) Increased SOM Improves Soil Water Holding Capacity Soil organic matter (%) Uncultivated Sites Separated Dairy Liquid Separated Dairy Solid Soil water No manure manure % moisture Field capacity Wilting point Available water Source: Soil Fertility and Fertilizers, Havlin et al., 2005 Nitrate-N leached from soil soils (lbs/acre) Increased SOM Improves N supply Nitrate N leached during 60 day incubation period Mineralization rate=50 lbs/60 days Mineralization rate=56 lbs/60 days 91.2 Crop Fields 71.6 Uncultivated Sites Nitrate-N concentration (lbs/acre) Nitrate-N leached during incubation period In fields with history of separated dairy liquid vs solid Mineralization rate=48 lbs/60 days Separated Dairy Liquid Mineralization rate=52 lbs/60 days Separated Dairy Solid 5

6 End of season cornstalk nitrate N test (CSNT) Soil organic matter (SOM) contains about 5% N. During a single growing season 1 4% of the SOM is mineralized to inorganic N. 1% 2% mineralization 20 lbs N/acre 1% 4% mineralization 40 lbs N/acre This is one reason it is very difficult to accurately predict the N fertilizer requirement of a crop. The amount of N a crop will remove or uptake is fairly uniform from year to year, but the amount of N available to the crop from the soil changes from year to year. Critical levels for CSNT Summary Balance nutrient inputs and outputs Soils have limited water and nutrient carrying capacity Imbalances cause nutrient losses Account for all nutrient sources TEST: manure, soil, crops Lots of nutrient forms, reactions, pathways. N mineralization converts organic N to inorganic N. Computer model can do the math for you. 6