ARS | Publication request: Effect of Dietary Protein on Ammonia Emission from Dairy Manure

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 14, 2010
Publication Date: July 11, 2010
Citation: Lee, C., Hristov, A.N., Dell, C.J., Feyereisen, G.W., Kaye, J., Beegle, D. 2010. Effect of Dietary Protein on Ammonia Emission from Dairy Manure [abstract]. American Dairy Science Association Meeting Abstract. 93:690.

Technical Abstract: The objective of this experiment was to investigate the effect of dietary crude protein concentration on ammonia (NH3) volatilization from dairy cow manure. Two types of manure were prepared by feeding lactating dairy cows diets with 16% (DM basis; HighCP) or 14% CP (LowCP). The manure was used in 2 experiments. In Exp. 1, 400 g of each manure (1.7:1.0, feces:urine) were placed in sealed steady-state flux chambers connected to a photoacoustic infrared gas analyzer and incubated for 5 d at 25°C in duplicate to measure the NH3 emitting potential of manure. Ammonia emission rates were 202 and 132 (mg/h; P < 0.001) for HighCP and LowCP manure, respectively. Cumulative NH3 emission was 45% less (P < 0.001) for LowCP compared with HighCP manure. In Exp. 2, LowCP and HighCP manure was applied to 61 × 61 × 61 cm lysimeters collected from a Hagerstown silt loam (fine, mixed, mesic Typic Hapludalf) in a complete randomized design. Manure was applied to each lysimeter immediately after mixing feces and urine (as in Exp. 1). The application rate was 9.3 g of N/lysimeter, corresponding to a field application rate of 300 kg N/ha. The HighCP manure had higher N content (4.4 vs. 2.8%, DM basis) and proportion of ammonium and urea-N in total manure N (51.4 vs. 30.5%) than the LowCP manure. As a result, more LowCP than HighCP manure (2.36 vs. 1.65 kg) was applied to each lysimeter. After manure application, NH3 emissions were measured using a photoacoustic infrared gas analyzer at 3, 8, 23, 28, 50 and 100 h. Ammonia emission was greater (P < 0.05) from HighCP- than from LowCP-manure amended soil. The area under the cumulative (100 h) NH3 emission curve for HighCP was smaller than the area for LowCP manure (56.8 and 114.8 mg NH3/m2/min × h, respectively). In conclusion, manure from dairy cows fed a 14% CP diet had decreased NH3 emitting potential and resulted in 50% lower ammonia emission when applied to soil, compared to manure from cows fed a 16% CP diet.