Phosphorus is an essential nutrient for clover growth and pasture production. One of the best sources of organic phosphorus is reactive phosphate rock (RPR). This phosphate-rich product is mined from rock deposits at various locations around the world, washed to remove excess salt, and ground to produce a consistent product.
RPRs differ from superphosphate products in that very little of the phosphate is in a highly soluble form. Typically, around 5% of the phosphate in RPR is water-soluble, compared to 85% in a superphosphate. RPRs have much higher proportions of slowly available phosphate. This phosphate is gradually released over a period of time, rather than all being available soon after application.
These characteristics mean that RPRs are ideal for use where environmental issues are a concern, as there is much less risk of phosphate run-off entering waterways. RPR products are also ideal to use as maintenance fertilisers. They are not so suited to use as capital fertilisers.
RPR can be applied to soils by itself, or it can be combined with other BioGro-certified materials to create products with a defined spectrum and concentration of nutrients.
The BioGro-certified phosphorus products available through Altum include: