Abstract One of the major problems in the efficient running of biogas plants is proper management of their slurry due to the increased volume of cattle dung from 1 to 1·6–1·7 times. Therefore, a laboratory study was undertaken to determine the contents of some plant nutrients in the liquid and semi-solid portions. A known weight of slurry was centrifuged at 6000 rpm for half an hour and the liquid and semi-solid portions were separated and weighed. The slurry as a whole, liquid and semi-solid portions, was analysed for its N, P, K, Zn, Cu, Mn and Fe content. It was observed that if the slurry from the biogas plant is collected directly into the underground manure pits and the excessive liquid is allowed to leach down, then the losses of K, Zn, N, Cu, Mn, Fe and P would be 36·5, 25·0, 21·5, 14·8, 5·9, 4·9 and 2·7%, respectively, Moreover, the slurry could be further decomposed and applied easily in the fields.