In many acid soils in the world, soil fertility limitations constrain successful crop production. These soils usually are low in plant-available P and often have a high P-fixing capacity that results in low efficiency of water-soluble P (WSP) fertilizers such as triple superphosphate (TSP) or diammonium phosphate (DAP) by crops. Application of unprocessed PR to soil can be an attractive alternative to WSP fertilizers in such cases.
Also in Organic agricultural systems fertilisers like single super, MAP and DAP are unacceptable inputs, so P is often deficient for crop and pasture production on organic farms. A survey of organic farms in south-eastern Australia in 2005 reported available soil phosphate (Olsen P) levels that were frequently less than 6mgP/kg which indicated deficiencies. Improved P management, including developing a fertiliser that would suit organic farming regulations, is required to sustain and increase production on these farms. Rock phosphate (RPR) is a natural products, suitable for organic use similar to our mined gypsum products.
Elemental Sulphur blended in with the RPR can be required to overcome the constraint on the dissolution of RPR resulting from frequent periods of low soil moisture. From the 2005 study it was concluded that for the south-eastern cropping zone, co-treatment of ground-reactive rock phosphate with finely ground elemental S at ratios (RPR:S) of at least 2:1, depending on soil pH, is required for effective use of RPR even in strongly acidic soils. It was recommended that organic farmers may recover soil P fertility by applying RPR to their most acidic paddocks, postponing soil liming and managing the paddocks to conserve soil moisture.
REGYP’s Phosphate Rock products are an excellent natural source of phosphorus, calcium and many essential trace elements. Phosphate rock has up to one fifth the neutralizing power of lime.
Phosphate Rock (PR) can provide exceptional results and make P readily available for plants, especially if the soil is Acidic (pH 5 to 6) and low in calcium (Ca) and the soil has low levels of available P.
Phosphate Rock is a slow release fertilizer and continuously adds P to the soil over a longer period of time. The benefits to farmers are lower costs and lower labour requirements because Phosphate Rock does not have to be applied every year.
Rock phosphate, can mineralize the soil and improve the quality of crops and soil structure. However, its principal uses are to build phosphate fertility where levels are low and/or to increase rooting activity in transplants and sprouting seeds.
Unlike acidulated phosphates, such as triple super phosphate, Phosphate Rock offers a small per cent age of its total phosphate content as immediately available. Large quantities of available phosphate from acidulated phosphates tend to fix or bond to cation (positively charged ion) nutrients in the soil, rendering the phosphate itself unusable, and also locking up the cations.
All this occurs before plants have a chance to use much of this very important phosphate. The slow release nature of Phosphate Rock allows plants good opportunity for access before fixation can occur. Additionally, fewer cation nutrients (such as calcium, magnesium, and potassium) can be bound up by free phosphate ions. Applications of Phosphate Rock can last 5 years or longer, depending on soil conditions.
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