Soil enzyme activities can be used as potential indicators of nutrient cycling processes and fertility management, particularly in long-term organic and conventional farming systems .
Soil enzymes are considered sensitive to disturbances in paddy ecosystem. Their activities were increased to different degrees by organic manure incorporation and gave a significant and positive relationship of enzyme activity with organic C and total N . Conversely, the addition of heavy metal and phytotoxin to soils reduced C turnover and nutrient availability .