Reducing nitrogen losses and improving its utilisation by crops requires a co-ordinated and multi-disciplinary research programme to develop the necessary strategies and techniques. Nitrogen losses during the storage, handling and spreading of slurries and solid manures may be influenced by several factors. To meet the research objectives, it is essential to identify the store design and management options which are likely to conserve nitrogen, whilst being acceptable to farmers. The general criterion of acceptability is that of cost neutrality, ie. the costs of conservation measures should be less than or equal to the nutrient value saved. This study will focus on identifying and developing mixing, aeration and covered storage to conserve nitrogen in solid manures and slurries, and will quantify rates of nutrient loss as functions of duration of storage. This project will comprise three stages: (1) farm-scale experiments to measure current nitrogen losses during typical storage periods, (2) laboratory experiments to quantify the effects of various management options, in an accelerated programme, and (3) the work will conclude with limited farm-scale trials of the best options. The work will contribute towards a quantifiaction of the nitrogen losses from an important part of livestock farming. In providing detailed measurements of leachate and emissions under known conditions, the results will not only contribute towards the development of improved farming systems, but will also complement other studies aimed at establishing reliable data on the overall pollution risks arising from the UK livestock farming sector.