Effect of Temperature on Alkaline Phosphatase Activity in Alfisols and Vertisols of Andhra Pradesh

Abstract

Soil enzymes play an important role in catalyzing several important reactions necessary for the life processes of microorganisms in soils thereby stabilizing the soil structure, the decomposition of organic wastes, organic matter formation, and nutrient cycling. Alkaline phosphatase belongs to the group of Phosphomoesterases and helps in the mineralization of phosphorus from organic form. The activity of enzymes in soils is influenced by the temperature, moisture and pH of soil. The temperature increase caused by global warming have a profound influence on soil enzymes. Every enzyme has its optimum temperature below which the enzyme activity is less due to inactivation. Further, with an increase in temperature, the enzymes get denatured resulting in a decrease in nutrient availability and indirectly affecting productivity. To study the effect of temperature on soil enzyme activity, four alfisols and four vertisols were collected and laboratory incubation studies were carried out at different temperatures ranging from 20oC to 90oC. The alkaline phosphatase activity (µg of 4-nitrophenol g-1 soil h-1) ranged from 23.08 to 120.55 in alfisols while in vertisols the activity varied from 66.58 to 536.88. Temperature coefficient values (Q10) were calculated in the temperature range of 20 to 90oC. These values depend on the type of soil which varied from 0.31 to 1.88 in alfisols and 0.38 to 1.92 in vertisols