Testing Selected Soils from Bamyan Center Agricultural Research Farms for Initial Macro and Micro Nutrients with Focus on Phosphorus Availability

Phosphorus (P) and micronutrients deficiencies are common in alkaline soils. Alkaline soils make up some of the most productive agricultural lands in the Bamyan center of Bamyan province in central Afghanistan and little is known about the phosphorus fertility status of these soils. The objectives of this study were to determine the soil fertility status of 4 soils collected from the four research farms in Bamyan center and also to conduct P incubation studies on these soils to determine the fixation and availability of added P. The experimental design was a randomized complete block with 3 replications of each treatment. Soils used in this study had pH > 8.0, free CaCO3 contents of 9.3-10% and texture ranged from silty clay loam to sandy loam. Seven rates of P (0, 5.6, 10.9, 16.4, 21.8, 32.8, 43.7 mg kg-1) were added as monocalcium phosphate [Ca (H2PO4) ·2H2O]. Soils were incubated at approximately 0.03 MPa soil tension for 15, 30, 45, 60, 75 and 90 days at 25° C and the Mehlich 3 soil test was used to determine available P. Mehlich 3 extractable P did not change consistently with time so data were averaged over all 6 sampling periods to determine the effects of P rate on Mehlich 3 P soil test levels. Soils segregated into two groups of two soils each that responded similarly in their response to P applications. Approximately 70 percent of the applied P remained available in one group of soils, while in the other group of soils, approximately 50 percent of the applied P remained available.