Direct exports of phosphorus from fertilizers applied to grazed pastures in Australasia

The 4R concept was developed to help mitigate P exports. This review investigates the factors affecting P exports soon after the application of mineral fertilizers and studies quantifying its potential impact in different systems. Initially, P fertilizers and reactions that might affect their short-term P export potential are reviewed, along with P transport pathways. We then review studies quantifying the short-term impact of fertilizer application in different regions. Under poor management, recently applied fertilizer can contribute a considerable proportion (30–80%) of total farm P exports in drainage, but when fertilizer is well-managed, that figure is expected to be <10%. We use three model systems of varying hydrology common to Australasia to demonstrate the principles for selecting fertilizers that are likely to minimize P exports soon after their application.