Phosphorus status of pastoral soils where reactive phosphate rock fertilisers have been used.

摘要

The dissolution rate of Sechura phosphate rock (particle size 75-150 mum) was determined at 95 New Zealand sites with a range of soil and environmental properties. Rates ranged from 0 to 70% of the phosphate rock dissolved per year with an average dissolution rate of 31% /year. An initial model based on stepwise linear regression analysis indicated that the rate of dissolution was negatively associated with soil pH and positively associated with rainfall and exchangeable soil magnesium. There was also an effect of soil type and drainage. The amount of residual RPR accumulated from previous fertilizer application can be determined by a new soil test. This, together with the dissolution rate estimated from the nature of the RPR and the soil and sitefactors, can be used to indicate likely soil P status.