Annual Variation in Soil Enzyme Activity in a Paddy Field: Soil Temperature and Nutrient Availability Are Important for Controlling Enzyme Activities

Abstract EN

Annual variations in enzyme activities involved in carbon (C), nitrogen (N), phosphorus (P), and sulfur (S) cycling and soil physicochemical properties were examined in a Japanese paddy field.

All the enzyme activities determined at the field soil temperature (range, 2.2°C–28.3°C) increased exponentially with soil temperature (p<0.001).

Significant negative correlations were found between Bray-2P concentration and the ratio of acid phosphatase to β-D-glucosidase activity (Spearman r = −0.631, p = 0.005) and between total N and the ratio of L-asparaginase to β-D-glucosidase activity (r = −0.612, p=0.007), suggesting that in accordance with the resource allocation model, acid phosphatase and L-asparaginase were synthesized by microorganisms depending on the temporal changes in soil P and N availability.

These results suggest the significance of soil temperature in controlling in situ enzyme activities in paddy soil and also that the stoichiometry of enzyme activities associated with C, N, and P acquisition reflects the soil nutrient availability.