Soil Use and Management (1999) 15, 56^61 Leaching and balances of phosphorus and other nutrients in lysimeters after application of organic manures or fertilizers B. Ule¨ n Abstract. A long-term lysimeter experiment with undisturbed monoliths studied leaching behaviour and bal- ances of phosphorus (P), potassium (K) and nitrogen (N) during a seven year crop rotation on four types of soil receiving inorganic fertilizers, manure and grass compost respectively. It was shown that application of manure did not lead to any direct change in nutrient leaching, unlike the application of fertilizers to soils of normal ferti- lity. However, soil type considerably affected the nutrient concentrations in the drainage water. Manure applied in amounts equal to the maximum animal density allowed by Swedish legislation slightly over- supplied P and N (0.5^3.5 and 18^38 kg ha 71 y 71 respectively) compared to the crop requirement and leaching losses for most of the soils. The relationship between lactate-soluble P in the topsoil and the concentrations of dissolved P in the drainage water was very strong. However the strength of this relationship was dependent on just one or two soils. P losses from a fertile sandy soil were large (1^11 kg ha 71 y 71 ) throughout the crop rotation and average crop removal (13 kg ha 71 y 71 ) plus the leaching losses were not balanced (average deficit 3^6kgha 71 y 71 ) by the addition of fertilizer, manure or grass compost. No decreasing trend was found in the P losses during seven years. However, the K deficit (average 26 kg ha 71 y 71 ) led to a significant reduction in the leaching trend from this soil.The other soils that had a smaller K deficit showed no significant reduction in the leaching of K. Keywords: Lysimetry, phosphorus, leaching, soil, nutrient balance, fertilizers, manures, composts, Sweden INTRODUCTION F arming using only manure or compost additives has increased during recent years as ecological farming has become more common. It is a Swedish government objective that by the year 2000, ten per cent of arable land should be cultivated ecologically; similar targets exist in other coun- tries within the European Union. A closed nutrient cycle is needed on such farms, although some input of nutrients may come from imported animal feedstuff. However, widespread use of nutrients in organic form may increase the risk of leaching losses through the soil. For example, organic coat- ings may modify the sorption properties of the mineral parti- cles causing increased P mobilization (House et al., 1998). Organic N has also been associated with large N losses (e.g. Kemppainen, 1995) as some of the applied N may be minera- lized at a time when it cannot be used by the crop. A sufficient supply of K may also be a problem in ecological farming, due to the high requirements of leys. Soil monoliths have been widely used to study the leaching behaviour of nutrients through the soil (e.g. Uhlen, 1994; Shepherd & Webb, 1996, Jensen et al., 1998, Meissner et al., 1998). A great advantage with this technique is that the trans- port in the unsaturated zone can be measured under con- trolled conditions and without any influence from groundwater. Drainage losses may be composed of two com- ponents (Ule¨ n et al., 1998); a rapid loss induced in the topsoil that is transported by preferential flow, and a slower loss via the soil matrix. Processes in the vicinity of the drainage pipes may also affect the leaching from fields but are not mea- sured in lysimeters. This was indicated by Sharpley et al. (1977) who found the phosphorus export in drainage water to be more closely correlated with extractable P at the depth of the pipe drains than in the topsoil. Moreover, leaching of dis- solved phosphate may be triggered by high groundwater levels or flooding causing reduced conditions in the soils (Sallade & Sims, 1997; Martin et al., 1997). However, the main source of P is usually the topsoil (Òygarden et al., 1997) and lysimeters may therefore give a good indication of the drai- nage losses. In addition, the potential risk of poor ground- water quality may also be evaluated with lysimeters. The aim of the present study was to investigate leaching behaviour and balances of P, K and N from different soil types which had received applications of fertilizers, manure or grass compost.The focus was on P, since this element may be the most difficult to balance in ecological farming and causes environmental problems when concentrated in inland water systems. Department of Soil Sciences, Division of Water Quality Management, Swed- ish University of Agricultural Sciences, Box 7072, SE-750 07 Uppsala, Sweden. Fax: 46 -18673430. E-mail: Barbro. Ulen@mv.slu.se 56 Leaching and nutrient balances