All growing plants need phosphorus; however, regardless of how much phosphorus is added to the soil, only the water soluble portion can be utilized by the plant.
Agnihotra Ash and Water Soluble Phosphates
by Dr. Tung Ming Lai, Denver, Colorado, USA
I did some lab testing on Agnihotra ash.The results are interesting. 0.1g of ash was shaken with 25 ml of water for fortyeight hours and then the water-soluble phosphate content was measured. The same amount of ash was shaken with two different soils (5g) from Colorado (also 25 ml of water) and phosphate content was measured after forty-eight hours of being shaken.