PHOSPHORUS FORMS IN CALCAREOUS SOIL AS AFFECTED BY IRRIGATION WATER SALINITY

Öz

This study was carried out on five calcareous soils of Egypt characterized by different content (%) of calcium carbonate (CaCO3) and other physical and chemical properties to study their content of different forms of phosphorus and its affected by soil properties and irrigation water salinity. The tested calcareous soils were used in a greenhouse experiment, where these soils were planted by barley and irrigated by tap water and four sources of artificial saline water. The artificial saline water were prepared at 1000 and 2500 mg TSS/l (A1 and A2). Each level of TSS (total soluble salts) have one values (B1 or B2) of sodium adsorption ratio (SAR) of 6.31 and 23.26 for A1 and 9.97 and 36.11 for A2. Plants were harvested at harvesting stage. The dry matter yield of the harvested plants was measured and also its content of P was determined. Some chemical properties of the studied calcareous soils and the content of different P forms .i.e. total, available, organic, inorganic, calcium, aluminum and iron phosphate ( T-P,A-P, O-P, I-P, Ca-P, Al-P and Fe-P) were determined. Chemical properties .i.e. pH , EC and the content of soluble ions were increased with the increase of irrigation water salinity and sodicity . The found changes in these properties were varied from soil to another. Dry matter yield of barley plants (straw and grains) and its content of P were clearly decreased with the increase of soil content of CaCO3 and increase of irrigation water salinity and sodicity .The level of this negative effect on grains was high than that found with straw. Generally the studied calcareous soils characterized by low content of P. Most of this content was found in I- P form (>90% of T-P). The major fraction of I-P was Ca-P followed by Al-P. The content of different P-forms was related with the studied soil properties. Irrigation water salinity and sodicity have a clear effect on calcareous soils content of P-forms especially O-P, Al-P and Ca-P. The conclusion of this study is : under similar conditions some sources of saline water may be used in irrigation especially at the short-term of the earlier periods of calcareous soils reclamation.

Anahtar Kelimeler

• Calcareous soils, Salinity, Sodicity, Phosphorus, Barley