Effect of flooding management on carbon content of soil and plant after cessation of paddy rice cultivation

Abstract

We measured soil carbon (C) and its stable isotopic composition in paddy fields that had received different fallow treatments for 6 years to investigate how management practices influenced the response of soil C. The experiment compared 4 fallow treatments in neighboring fields: mowing twice a year and no tillage (MN), mowing twice a year and puddling once a year (MP), and flooding to 5 or 15 cm and puddling (WP5, WP15) to prevent succession to wasteland and thus permit future cultivation. MN had the potential to increase soil C more than MP5 through larger root and shoot buildup. However, the total soil C content to a depth of 30 cm was significantly higher in WP5 (13.7 Mg C ha-1) than in MN (11.8 Mg C ha-1). The dry-fallow management increased plant growth while reducing soil C. The large root dry weight in MN and MP could have increased soil C through high root turnover, whereas land use change from flooding to dry-land masked the abundant C input. After cultivation stops, flooding plays a significant role in preventing root growth and C sequestration in fallow paddy fields. © 2013, ALÖKI Kft., Budapest, Hungary.