Alkaline phosphatase activity and kinetics in organic residues -- impacted soils.

Soil phosphmonoesterases play an important role in controlling phosphorus cycling for crops, especially in P- deficient soils. Phosphomonoesterases markedly affected by addition of organic residues depending on source, rate, and maturity and stability of these residues. An incubation experiment was conducted to evaluate alkaline phosphatase activity and kinetics of two soils (silty clay and loamy sand) after addition of different organic sources (cow residue, alfalfa leaves, wheat straw and poultry residue) at rate of 2 %. The experiment was set out in randomized complete design with three replicates. Amended and control soils were incubated at 30ºc for 30 days. Results showed that alkaline phosphatase activity of amended soils was significantly higher than that of control soil, except soil amended with wheat straw. Enzyme activity was differed according to the type of organic residue with superiority of poultry residue. Alkaline phosphatase activity of silty clay soil was significantly higher than that of loamy sand soil. Data also revealed that Vmax and Km values of amended soils were higher than these of unamended soil. Higher Vmax and Km value were associated with using of poultry residue. Estimated Vmax and Km values varied with the type of transformation used to linearize Mechaelis--Menten equation which followed the order: Hanes -- Wolf > Eadie -- Hofstee > Line Weaver -- Burk. [ABSTRACT FROM AUTHOR]