Model for calculating potassium requirements for grazed pastures

Abstract

A model has been developed for calculating the potassium (K) requirements of grazed pastures. It assesses K losses in animal products, in transfer from the grazing area, and in drainage, using knowledge of the type of stock, stocking rate, land slope, and mean annual rainfall. Potassium supplied by the soil from residual fertiliser K and through weathering of clay minerals is then subtracted from these losses to give the fertiliser required. An adjustment can be made for those areas which lose or receive extra K in hay or silage.

Keywords:

• fertilisers
• potassium requirement
• pastures
• nutrient cycling
• exchangeable potassium
• potassium reserves
• weathering
• leaching
• stock
• slopes