Estimation of potassium losses from a grazed dairy farm in Taranaki

Abstract The potassium (K) lost through animal products (milk, calf and culled stock) and transfer of excretai K to the dairy shed and raceways, was estimated at 1.6 kg/stock unit (SU) for a dairy farmlet of small herd size, assuming the cows spend 5% of the year off the paddock. This loss increased to 2.5 kg K/SU if the cows spend 10% of the year off the paddock as is likely on a dairy farm with a larger number of cows. These values are lower than the 4 kg K/SU currently used by the Ministry of Agriculture and Fisheries as the animal loss factor (ALF) in their fertiliser advice scheme for dairying on flat-rolling country in New Zealand.