Soil Phosphatase and Urease Activities Impacted by Cropping Systems and Water Management.

Soil enzymes can play an important role in nutrient availability to plants. Consequently, soil enzyme measurements can provide useful information on soil fertility for crop production. We examined the impact of cropping system and water management on phosphatase, urease, and microbial biomass C in soils collected from potato fields. Activities of acid phosphatase, alkaline phosphatase, phosphodiesterase, and urease were 28, 80, 86, and 54% higher, respectively, in the soil improving cropping system than in the continuous potato system. Irrigation also increased these soil enzyme activities. Under rainfed management, microbial biomass C level was highly correlated with phosphatase and urease activities.  When measured under buffered conditions, urease activity was highly correlated with rainfed potato yield. To the extent that urease is an indicator of plant N availability, this may reflect the influence of N availability on yield. This study showed that both cropping system and water management influence the activities of several enzymes considered important for plant uptake of N and P.