References
- Hook Presto, M., Algers, B., Persson, E., Andersson, H.K., 2008. Different roughages to organic/finishing pigs-Influence on activity behaviour and social interaction. Livest. Sci.
- Williams, J.R., Chambers, B.J., Hartley, A.R., Ellis, S., Guise, H.J., 2000. Nitrogen losses from outdoor pig farming systems. Soil Use Manage. 16: 237–243.
- Evans, R., 2004. Outdoor pigs and flooding: an English case study. Soil Use Manage 20:178–181.
- Brandt, M., Lehmann, B., Selinger, S., Wildhagen, H., 1995a. Untersuchungen zur Freilandhaltung von Mastschweinen. In: Beitrag zur 3: 61–64.
- Petersen, S.O., Kristensen, K., Eriksen, J., 2001. Denitrification losses from outdoor piglet production: spatial and temporal variability. J. Environ. Qual. 30:1051–1058.
- Sommer, S.G., Sogaard, H.T., Moller, H.B., Morsing, S., 2001. Ammonia volatilisation from sows on grassland. Atmos. Environ. 35: 2023–2032.
- Eriksen, J., 2001. Implication of grazing by sows for nitrate leaching from grassland and the succeeding cereal crop. Grass Forage Sci. 56:317–322.
- Ceccanti, B., Masciandaro, G. 2003. Stable humus-enzyme nucleus: the last barrier against soil desertification. In Preserving soil quality and soil biodiversity-The role of surrogate indicators. M.C. Lobo & J.J. Ibanez (eds.), pp. 77–82. CSIC-IMIA, Madrid.