Abstract
Adding gypsum and/or straw is a common practice for ameliorating saline-alkali soils. However, the effect of amendment on soil CO2 is poorly known. An incubation experiment was conducted for over two years in a saline-alkali soil of Yanqi Basin, which included four treatments: control, gypsum addition (Ca), wheat straw addition (S) and gypsum-wheat straw combination (Ca+S). We continuously monitored soil CO2 concentration, temperature and moisture at 15, 30, 45 and 60 cm. There was a clear seasonality in soil CO2 under all four treatments, which was generally similar to those in soil temperature and moisture. Straw addition led to a significant increase in soil CO2 over 0–60 cm in summer. While there was a significant increase of soil CO2 with gypsum addition only, soil CO2 significantly decreased with the addition of gypsum and straw (relative to straw addition only) during autumn and winter in 2014. Interestingly, integrated soil CO2 was lowest in soil profile under the Ca+S treatment during winter and spring. Our study implies that different amendments of organic matter and gypsum may result in various responses and interactions of biological, chemical and physical processes, with implications for the carbon cycle in saline-alkaline soils of arid region.
Highlights
Saline-alkali soil is widely distributed in arid and semiarid areas due to extremely low precipitation and strong evaporation[1,2]
The objective of this study is to evaluate the impacts of amelioration on soil CO2 dynamics, and to explore the underlying mechanisms regulating the variability of soil CO2 in an arid saline-alkali soil
The amelioration of saline-alkali soil with gypsum and/or wheat straw had a significant effect on soil CO2 in the arid region
Summary
Saline-alkali soil is widely distributed in arid and semiarid areas due to extremely low precipitation and strong evaporation[1,2]. Improvement of saline-alkali soil is one of the effective measures to enhance agricultural production. A number of studies have demonstrated that adding organic materials significantly increases organic carbon content and microbial activities, thereby enhancing soil CO2 production and emission[17,18]. Some studies indicated gypsum addition has no significant influence on soil CO2 emission, due to small change in labile carbon pool or soil microbial biomass[19,20]. Kaur et al.[21] found an increase of microbial biomass carbon in gypsum-amended soil as a result of improvement in soil physicochemical environment. There are limited studies of CO2 emission in saline-alkali soil with combination of organic matter and gypsum amendments. Studying the variability of soil CO2 is critical to understanding the influencing mechanisms of amelioration on the carbon cycle in saline-alkali soils
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