MEASUREMENT AND MANAGEMENT OF AMMONIA VOLATILIZATION FROM DAIRY SLURRIES

Authors: THOMPSON, RODNEY - POST-DOC, ARS; Meisinger, John

Submitted to: Proceedings of Intl Symposium Addressing Animal Production and Environment
Publication Type: Proceedings
Publication Acceptance Date: 11/27/2001
Publication Date: 12/10/2001
Citation: THOMPSON, R.E., MEISINGER, J.J. MEASUREMENT AND MANAGEMENT OF AMMONIA VOLATILIZATION FROM DAIRY SLURRIES. PROCEEDINGS OF INTL SYMPOSIUM ADDRESSING ANIMAL PRODUCTION AND ENVIRONMENT. 2001.

Interpretive Summary: Large ammonia volatilization losses can occur following surface application of dairy slurry. Information is needed on field methods to measure ammonia volatilization and on losses as affected by management factors. A comparison was made of ammonia losses using a mass-balance micro-meteorology method and a wind-tunnel method. The wind tunnels gave qualitatively similar results to the mass-balance method, but losses were lower with wind tunnels the first day after application. The wind tunnels are well suited for studies comparing several treatments. A series of wind tunnel studies examined ammonia losses as affected by: soil-surface condition, tillage, and slurry total solids content. The soil-surface studies showed that the total ammonia loss was 50% greater from a grass surface than from bare soil, and that surface crusting did not effect losses. Studies comparing immediate incorporation by tillage showed that either the moldboard plow or the disk could reduce losses to less than 5%; compared to a 45% loss from unincorporated slurry. Chisel plow tillage resulted in a 10% loss. Studies comparing slurry total solids content showed that viscous slurries (greater than 10% solids) and liquid slurries (less than 10% solids) lost the same total amount of ammonia. However, viscous slurries lost more during the first 18 hours, while liquid slurries lost more after 18 hours. These results show that ammonia loss estimates can be improved by considering soil-surface conditions. Immediate incorporation is a very effective method to minimize losses.

Technical Abstract: Large ammonia (NH3) volatilization losses can occur following surface application of dairy slurry. Information is needed on field methods to measure NH3 volatilization and on NH3 losses as affected by management factors. A comparison was made of NH3 losses using the integrated horizontal flux (IHF) micro-meteorology method and the wind-tunnel (WT) method. The WT method gave qualitatively similar results to the IHF, but losses were lower with the WT immediately after application, due to lower WT wind speeds. The WT are well suited for replicated comparative studies, i.e. when treatment comparisons are the primary goal. A series of WT studies examined NH3 losses as affected by: soil-surface condition, tillage, and slurry total solids (TS) content. The soil-surface studies showed that the total NH3 loss was 50% greater from a grass surface than from bare soil. Surface crusting had no discernable effect on NH3 loss. Studies comparing immediate incorporation by tillage showed that either the moldboard plow or the tandom disk, could reduce NH3 losses to <5%; compared to a 45% loss from unincorporated slurry. Immediate incorporation with a chisel plow resulted in a 10% loss of NH3. Examinations of slurry TS content showed that viscous slurries (TS >100 g/kg) lost more NH3 than liquid slurries (TS <100 g/kg) during the first 18 hours, but liquid slurries lost more NH3 after 18 hours. Total NH3 loss was similar for both slurry types under the hot summer conditions of the study. These results show that NH3 volatilization can be a major problem for dairy slurries. Ammonia loss estimates can be improved by considering soil-surface conditions. Immediate soil incorporation is one of the most effective method to minimize NH3 losses.