Stimulation of nitrogen turnover due to nutrients release from aggregates affected by freeze-thaw in wetland soils

Publication date: Available online 29 December 2016 Source:Physics and Chemistry of the Earth, Parts A/B/C Author(s): Yang Song, Yuanchun Zou, Guoping Wang, Xiaofei Yu The freeze-thaw phenomenon will occur more frequently in mid-high latitude ecosystems under climate change which has a remarkable effect on biogeochemical processes in wetland soils. Here, we used a wet sieving procedure and a barometric process separation (BaPS) technique to examine the responses of wetland soil aggregates and related carbon and nitrogen turnover affected by the freeze-thaw treatment. Wetland soil samples were divided into a treatment group and a control group. The treatment group was incubated at temperatures fluctuating from 10°C to -10°C, whereas the control group was incubated at the constant temperature of 10°C. A 24 h process was set as the total freeze-thaw cycle, and the experiment had 20 continuous freeze-thaw cycles. In our results, the freeze-thaw process caused great destruction to the >2 mm water-stable aggregates (WSA) fraction and increased the <0.053 mm WSA fraction. The dissolved organic carbon (DOC) content was stimulated during the initial freeze-thaw cycles followed by a rapid decline, and then still increased during subsequent freeze-thaw cycles, which was mainly determined by the soil organic carbon (SOC). The NH4 + and NO3 - content, respiration rate and gross nitrification rate were all significantly improved by the freeze-thaw effect. Because the...
Source: Physics and Chemistry of the Earth, Parts ABC - Category: Science Source Type: research