Increases of soil phosphatase and urease activities in potato fields by cropping rotation practices

Author: Zhongqi He ^*, C. Wayne Honeycutt, Timothy S. Griffin, Robert P. Larkin, Modesto Olanya and John M. Halloran

Received 10 January 2010, accepted 7 April 2010.

Abstract

Soil phosphatase and urease activities which are responsible for P and N mineralization, respectively, could be indicators of soil health for nutrient availability. In this work, we measured the activities of acid phosphatase, alkaline phosphatase, phosphodiesterase, and non-buffered and buffered urease in soils under rainfed and irrigated potato with different crop rotation managements. Compared with continuous potato (Solanum tuberosum L.) production, three-year rotation practices increased all soil enzyme activities in rainfed condition by 10 to 86%. Irrigation increased alkaline phosphatase, phosphodiesterase, and both unbuffered and buffered urease activities, but decreased acid phosphatase activity compared with no irrigation. 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.

Key words: Phosphatase, urease, potato, cropping rotation, irrigation, soil enzymes, microbial biomass carbon.