DAP fertiliser provides a good source of phosphorus (P) and nitrogen (N) for plant nutrition. It is highly soluble and therefore dissolves quickly in soil to release plant-available phosphate and ammonium. Although used by Landco Fertiliser, G-Phos (Guano) and SOA are preferred sources of P and N.
A notable property of DAP is the alkaline pH that develops around the dissolving granule. As ammonium is released from dissolving DAP granules, volatile ammonia can be harmful to sensitive plant seeds and plant roots in immediate proximity, this potential damage however is more common in high pH soils. To prevent the possibility of seedling damage, care should be taken to avoid placing high concentrations of DAP near germinating seeds unless pH is at acceptable levels (below 7 to be safe). The ammonium present in DAP is a good N source and will be gradually converted to nitrate by soil bacteria, resulting in a subsequent drop in pH. Therefore, the rise in soil pH surrounding DAP granules is a temporary effect. The initial rise in soil pH around DAP can influence the micro-site reactions of phosphate and soil organic matter.
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