The studies on the effect of buffer pH on soil phosphomonoesterase activity was carried out in laboratory conditions in alfisols using modified universal buffer with a pH range from 3-12. The pH of the MUB was adjusted to respective pH levels using 0.1 N HC1 or 0.IN NaOH respectively. The substrate p^_ nitrophenyl phosphate of 0.025 M concentration was prepared in MUB of corresponding pH and analyzed for phosphomonoesterase activity. The soils were also analyzed for the physicochemical properties like pH, EC, available nutrients, texture and organic carbon. The results indicated that there was significant increase in the activity of phosphomonoesterase in the pH from 3 to 6.5 and later a steady decrease till pH 12. Thus all the alfisols exhibited a single peak of phosphomonoesterase activity at pH 6.5. The mean activity of phosphomonoesterase at pH 6.5 was found to be 132 µg of 4-nitrophenol released g ^-1 soil h ^-1. The soils S-6, S-8 and S-10 recorded significantly higher activity of phosphomonoesterase at all the pH levels used in the study.

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