Abstract
Soil organic carbon (SOC) sequestration with enhanced stable carbon storage has been widely accepted as a very important ecosystem property. Yet, the link between carbon stability and bio-activity for ecosystem functioning with OC accumulation in field soils has not been characterized. We assessed the changes in microbial activity versus carbon stability along a paddy soil chronosequence shifting from salt marsh in East China. We used mean weight diameter, normalized enzyme activity (NEA) and carbon gain from straw amendment for addressing soil aggregation, microbial biochemical activity and potential C sequestration, respectively. In addition, a response ratio was employed to infer the changes in all analyzed parameters with prolonged rice cultivation. While stable carbon pools varied with total SOC accumulation, soil respiration and both bacterial and fungal diversity were relatively constant in the rice soils. Bacterial abundance and NEA were positively but highly correlated to total SOC accumulation, indicating an enhanced bio-activity with carbon stabilization. This could be linked to an enhancement of particulate organic carbon pool due to physical protection with enhanced soil aggregation in the rice soils under long-term rice cultivation. However, the mechanism underpinning these changes should be explored in future studies in rice soils where dynamic redox conditions exist.
Highlights
mean weight diameter (MWD) 86.46 ± 6.19c 109.52 ± 2.13b 110.80 ± 1.27b 125.77 ± 7.79a 132.24 ± 8.50a increase in crop yield, reduction in greenhouse gas emissions and pollutant immobilization as well as increased ability for crops to deal with environmental changes as well as accumulation of organic carbon[7]
We use a rice soil chronosequence shifted from salt marsh to rice cultivation approximately 700 years ago to explore the changes in soil microbial activity and soil functioning with Soil organic carbon (SOC) accumulation and stabilization under prolonged rice cultivation
Total SOC sharply increased from the uncultivated salt marsh at P0 to P50 and steadily increasing from P100 to P700 with prolonged rice cultivation
Summary
MWD (μm) 86.46 ± 6.19c 109.52 ± 2.13b 110.80 ± 1.27b 125.77 ± 7.79a 132.24 ± 8.50a increase in crop yield, reduction in greenhouse gas emissions and pollutant immobilization as well as increased ability for crops to deal with environmental changes as well as accumulation of organic carbon[7]. The changes in soil bio-activity for ecosystem functioning, microbial activity in particular, with carbon accumulation and stabilization have not yet been quantitatively assessed. Improved land management has resulted in carbon stabilization and sequestration in soil This process has been attributed to increased physical protection of the carbon[15] which reduces microbial access, chemical stabilization into a more recalcitrant form[16] and to changes in microbial community that result in lower rates of carbon transformation[17]. Little research has investigated if SOC stabilization with enhanced stable carbon storage would compromise soil bio-activity and/or soil ecosystem functioning in terms of reduced access to, or utilization of OM by, soil microbial community. The changes in soil microbial activity and functioning with SOC accumulation and stabilization have not yet been characterized for paddy soils under intensive rice cultivation. We try to fill the knowledge gap on carbon stability versus bio-activity for ecosystem functioning with OC stabilization in agricultural soils, taking rice soil as a particular case
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