Input and distribution of photosynthesized carbon in a flooded rice soil

摘要: [1] Photosynthesis by terrestrial vegetations is the driving force for C cycling between Earth and atmosphere. To evaluate impacts of photosynthates on dynamics soil organic matter (SOM) in a rice-soil system, we conducted an isotopic pulse-chase labeling experiment microcosm system. Pulse 13C was performed to rice plants at varying ages. Destructive samplings soils were end growing season. The distribution aboveground mass increased from 45–52% net assimilation during tillering stage 78–90% that maturing rice, whereas proportion retained roots decreased 28 2%. About 1–5% incorporated into mean 19.5% lost presumably respirations microorganisms. percentage assimilates significantly exponentially correlated rate root growth. Over season, estimated plant input 200 kg ha−1. Most present as humin-like substances Rice also produced 865 ha−1 residues which after harvest. It was, therefore, considered totally about 1065 atmospheric CO2 fixed season plants. increase content, however, less than input, suggesting mineralization native SOM occurred concomitantly.