Four soil samples were collected from the surface layer of some cultivated and uncultivated calcareous soils located in the areas of Wadi El-Assiut and its interference zone with the Nile valley at Assiut to evaluate the application effects of certain organic materials on some chemical properties and the available Ca and P of these soils. The organic materials included 1) humic acid (HA) 2) vinasse (V) 3) clover straw (CS) and 4) ethyllyene diamine tetra acetic acid (EDTA). They were applied to the soil samples at levels of 2.5 and 5.0%. Soil samples treated with organic materials as well as the controls were moistened to the field capacity and then incubated at 24±2ºC for different time periods (30, 60 and 120 days).

El-Kharga oasis, New Valley governorate is a promising area for increasing the cultivated areas in Upper Egypt. This area has variations in soil physical .i.e. soil texture and chemical properties. Therefore, its contents of plant essential nutrients may become concerned. The aim of this study is to investigate the available phosphorus content of some soils of El-Kharga oasis and its relation with soil texture and some other soil properties. Thirty nine soil samples were collected from 13 soil profiles representing 5 different locations. Three soil samples from three layers (0-20, 20-40 and 40-60 cm) were collected from each profile.The results showed that the available soil phosphorus ranged from 4.40 to 34.54 mg kg -1 . Levels of available P were low (< 6 mgkg -1 ), medium (6 -10 mg kg -1 ) and high (>10 mg kg -1 ) in 10.26, 35.90 and 53.84% of the soil samples, respectively .The average available P level differed with soil texture. It was 16.38, 13.41, 12.13, 9.25 and 7.66 mg kg -1 in sand, loamy sand, sandy loam, sand clay loam and clay textured soil samples respectively. Insignificant negative correlations were obtained between the available P and most of the discussed soil properties (clay fraction, OM, SP, ECe, CaCO 3 , soluble Ca and soil depth) with r values of (-0.2729,-0.2074, -0.3257,-0.2121,-0.0985, -0.2047 and -0.3905) respectively, except soil pH, sand andsilt fractions which had positive significant correlation with available P (r= 0.0095, 0.2877 and 0.0055 respectively).