Vertical Distribution of Phosphorus in the Soils of Western Rajasthan

The distribution of the different forms of soil phosphorus was studied in six soil profiles representing normal, alkali and saline alkali soils of western Rajasthan. The total P and other fractions of phosphorus, viz., organic, inorganic and available phosphorus were found to increase with the depth of the soil. Organic phosphorus was found to be positively correlated with organic carbon and clay. The inorganic phosphorus was found to be nearly 53.3 to 90.7 per cent of total P. The calcium phosphate was found to predominate in the soil profiles as compared to other fractions. The available phosphorus was found to be affected by the soil reaction and calcium carbonate content and, as such, a negative correlation was observed with pH and calcium carbonate content. The inorganic phosphorus fractions were found to affect the availability of phosphorus and a positive correlation was obtained between available P and Al-P and between Fe-P and available P.