Factors affecting the agronomic use of livestock wastes: Physico-chemical characteristics of the soil. Treatments carried out. Period of application and efficiency of use. Nitrogen in the soil: Nitrogen cycle. Reactions of nitrogen in soil. Nitrification. Denitrification. Immobilization. Mineralization. Nitrate pollution. Problem of nitrates. Eutrophication. Increase nutrient availability. Dissolved oxygen consumption. Indicators of eutrophication. Impact of livestock on greenhouse gases. Components of the atmosphere. CO2, CH4, N2O emissions. Total gaseous emissions from animal husbandry. Impact of odours from livestock farms: Olfactory pollution. Odour sources. Causes the emission of odours on farms. Main classes of odorous compounds. Concentration and odour threshold of perception. Techniques for measuring odours. Biogas and composting: Biomass waste from livestock. The different types of biological treatment. Biogas and anaerobic digestion. Composting and aerobic digestion.