Characterising the volumes and chemical characteristics of dairy sheep effluent in New Zealand

Milking sheep produce an effluent stream from the milking parlour that is either applied directly to land from the sump via spray irrigators, or is stored in an effluent pond for later land application. In order to characterise this effluent stream, a monitoring programme was undertaken with effluent samples collected over two lactation seasons (2014/15 & 2015/16) from three case study sheep milking farms. Typical effluent volumes generated ranged between 4-10 L ewe-1 day-1. The mean physical and chemical attributes of these effluent samples were: 0.54% dry matter (DM), 220 g nitrogen (N) m-3, 32 g phosphorus (P) m-3, 150 g potassium (K) m-3 and 22 g sulphur (S) m-3. The mean nutrient concentrations of dairy sheep effluent are lower than values reported for dairy goat and dairy cow effluents. The current fertiliser N, P, K and S value of dairy sheep effluent represents the equivalent of $0.58 m-3, which is slightly lower than the $0.76 and $1.15 m-3 calculated for dairy goat and dairy cow effluents, respectively, based on 2016 fertiliser value data. The lower value for dairy sheep effluent was a result of the lower concentration of the most expensive nutrient, P.