Availability of Some Soil Phosphate Reaction Products

Six well characterized reaction products of phosphorus which are commonly found in soils were prepared and tested under greenhouse conditions as a source of phosphorus for maize (Zea mays) and urd (Phaseolus mungo). Apatite and monocalcium phosphates were also studied for their plant availability.

Maize and urd showed different trends of availability. Monocalcium phosphate and potassium taranakite provided better availability as compared to other products when maize was the test crop. Calcium ammonium phosphate (I), monocalcium phosphate and calcium ammonium phosphate (II) proved to be better urces of available phosphorus for urd.

Apatite (included as an insoluble calcium phosphate source) was unavailable to both the crop plants. Similarly, potassium iron phosphate and ammonium aluminium phosphate provided little response