Prevention and Control of Losses of Gaseous Nitrogen Compounds in Livestock Operations: A Review

Abstract

Nitrogen (N) losses from livestock houses and manure storage facilities contribute greatly to the total loss of N from livestock farms. Volatilisation of ammonia (NH₃) is the major process responsible for the loss of N in husbandry systems with slurry (where average dry matter content varies between 3 and 13%). Concerning this volatilisation of NH₃, the process parameters of pH and air temperature are crucial. During a period of approximately 10 years, systematic measurements of NH₃ losses originating from a large variety of different livestock houses were made. One of the problems with NH₃ emissions is the large variation in the measured data due to the season, the production of the animals, the manure treatment, type of livestock house, and the manure storage. Generally speaking, prevention and control of NH₃ emission can be done by control of N content in the manure, moisture content, pH, and temperature[1]. In houses for growing pigs, a combination of simple housing measures can be taken to greatly reduce NH₃3 emissions[2]. In houses for laying hens, the control of the manure drying process determines the emission of NH₃[1]. Monteny[3] has built an NH₃ production model with separate modules for the emission of the manure storage under the dairy house and the floor in the house. Manure spreading is also a major source of NH₃ emission and is dependent on slurry composition, environmental conditions, and farm management. The effects of these factors have been employed in a model[4]. Losses via NO, N₂O, and N₂ are important in husbandry systems with solid manure and straw. The number of experimental data is, however, very limited. As N₂O is an intermediate product of complex biochemical processes of nitrification and denitrification, optimal conditions are the key issues in N₂O reduction strategies. We may expect that in the near future the emission of greenhouse gases will get the same attention from policy makers as NH₃. Sustainable livestock production has to combine low emissions of gaseous N compounds with acceptable odour emissions, low emissions of greenhouse gases, and acceptable standards of animal welfare. For the entrepreneur, the strategy must be built on the regulations, the special conditions of his farm, and what is reasonably achievable.