A modification of the ‘Superchoice’ phosphate maintenance model

Abstract

A modified version of the ‘Superchoice’ model for calculating maintenance phosphate fertiliser requirements of grazed pasture is presented. The modified version makes a judgement about the relative yield of pasture which should be grown for any given ratio of stocking rate: carrying capacity. This allows maintenance phosphate requirements to be calculated without direct assessment of pasture utilisation, thereby overcoming a major problem in applying the full ‘Superchoice’ model in hill country and extensive grazing situations. The modified version integrates well with the full ‘Superchoice’ model.

Keywords:

• phosphorus
• maintenance fertilisers
• grazed pastures
• nutrient modelling