Ammonia Volatilization from Wet Animal Manures C.W. Wood, J.J. Meisinger, P.A. Moore, Jr., and R.B. Thompson Auburn University, USDA-ARS, Beltsville, MD and Fayetteville, AR

I. Problems With NH 3 Volatilization Acid Atmospheric Deposition –raises pH of rainwater, more SO 2 dissolves –ammonium sulfate forms - oxidizes soil –releases sulfuric & nitric acid Eutrophication –water and land Loss of N to farmers Lowers N:P

II. Sources of NH 3 on Livestock Farms Manure Application Animal Housing Manure Storage Grazing Fertilizer Application Crops Descending Order of Importance Bussink & Oenema, 1998

III. Nature and Handling

% DM LiquidSemisolidSolid Description Thin to Thick Slurry As DefecatedPartially Dried Considerable Drying Water Water AddedAs DefecatedWater Removed Handling PumpedScraped Liquid Handling Equipment Semisolid or Solid Handling Equipment Solid Handling Equipment Loehr, 1974

Travelling Gun

Tank Spreaders

IV. Factors Affecting NH 3 Volatilization From Liquid Manures A. Time

Pig Slurry; New Zealand; 368 kg N/ha applied 15.5% of NH 4 -N

IV. Factors Affecting NH 3 Volatilization From Liquid Manures B. Those That Affect Transfer of Gas Between Soil Solution and the Atmosphere

Solution/Atmosphere Interface Mattila (1998) - cattle slurry - 0 NH 3 v with injection; band < broadcast Sommer and Ersboll (1994) - cattle and swine slurry- NH 3 v from injected slurry in tilled soil was 30% of that from unworked soil; harrowing before surface application reduced NH 3 v by 50% Sharpe & Harper (1997) - swine effluent -13% of TAN lost via spray drift, 69% more after settling

Solution/Atmosphere Interface Sommer et al. (1997) - pig slurry - trail hose application resulted in 1/2 TAN loss of splash plate application; trail hose more effective under large plant canopy and low solar radiation

Air Velocity Sommer et al. (1991) - cattle slurry NH 3 v rate increased to 2.5 m/sec; no change between 2.5 and 4 m/sec crust formation with increased wind speed may increase liquid phase resistance

Rainfall/Soil Moisture Beauchamp et al. (1982) - cattle slurry –rainfall depressed volatilization temporarily difficult to distinguish from effect of temperature (rainfall = lower temperature) may leach soluble ammoniacal N into soil Sommer et al. (1991) - cattle slurry –frozen soil prevented infiltration –NH 3 v rate low, but constant - 6-day cumulative loss high

IV. Factors Affecting NH 3 Volatilization From Liquid Manures C. Those That Affect Rate of Chemical Reaction

[ammoniacal N]

NH 3L NH 3G K HN = [NH 3G ]/[NH 3L ] NH 4 + NH 3 + H + K = [NH 3 ]x[H + ]/[NH 4 + ] CO 2 + H 2 O HCO 3 + H + K = [HCO 3 ]x[H + ]/[CO 2 ] Basic Chemistry

Swine Waste TAN

Cattle Waste TAN

Poultry Waste TAN

[ammoniacal N] Brunke et al. (1988) - surface applied swine and dairy slurries –linear relationship between ammonia volatilization and [ammoniacal N] Frost (1994) - surface applied cattle slurry –amount of dilution water added was linearly and inversely related to volatilization dilution of :1 water:slurry lowered specific volatilization/unit slurry by 50%

[ammoniacal N] Stevens et al. (1992) - surface applied cattle slurry –50% decrease with separation through 10- mm mesh plus dilution with 86% by volume of water –75% decrease with separation through 5-mm mesh plus dilution with 100% by volume of water

Temperature

Micro-meteorological studies Two applications to arable land (corn stubble) December m 3 ha kg NH 4 + -N ha -1 April/May m 3 ha kg NH 4 + -N ha -1

Rate NH 3 loss (gN ha -1 hr -1 ) Air temp hours Ammonia Loss from Cattle Slurry applied 30 April Total 8 day loss = 71% of NH 4 + -N rate 38 m 3 ha -1, applied to corn stubble measured with MM

hours Rate NH 3 loss (gN ha -1 hr -1 ) Air temp { 26 mm RF 11 mm RF Total loss = 19% of NH 4 + -N Ammonia Loss from Cattle Slurry applied 5 December rate 88 m 3 ha -1, applied to corn stubble measured with MM

pH

AR swine manure; 150 kg N/ha

AR swine manure; 150 kg N/ha; AlCl %v

Other Factors Soil CEC - minimum of 25 meq/100 g (Sharpe & Harper, 1995) Soil pH Atmospheric [NH 3 ] Plant absorption

Summary NH 3 volatilization causes environmental problems and economic losses to farmers NH 3 volatilization from liquid animal manures is fast Exposure to the soil surface enhances NH 3 volatilization from liquid animal manures Environmental factors have a large influence [ammoniacal-N] probably has the greatest influence Dilution and acidification can help control NH 3 volatilization from surface applied wet animal manures

Research Needs A coordinated research program is needed on NH3v from wet manures that encompasses a wide range of manures, weather conditions, and soil-tillage systems. Databases developed from such a research program would contribute to improved estimates of NH3v and improved management techniques for wet manures. Research should include a continuum from source to atmosphere.