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| Organic carbon fixation by iron and aluminum reactive minerals in farmland soil |
| Received:October 28, 2020 |
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| KeyWord:farmland soil;iron and aluminum reactive minerals;carbon sequestration;soil type;tillage system |
| Author Name | Affiliation | E-mail | | LONG Juan | College of Resource&Environment, Southwest University, Chongqing 400716, China
Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716, China | | | LIAO Yu-qin | College of Resource&Environment, Southwest University, Chongqing 400716, China
Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716, China | | | WEN Shou-xin | College of Resource&Environment, Southwest University, Chongqing 400716, China
Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716, China | | | MU Zhi-jian | College of Resource&Environment, Southwest University, Chongqing 400716, China
Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716, China
Key Laboratory of Arable Land Conservation for Southwest China, Ministry of Agriculture, Chongqing 400716, China | muzj@swu.edu.cn | | YANG Zhi-min | College of Resource&Environment, Southwest University, Chongqing 400716, China
Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716, China | |
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| Abstract: |
| In order to understand the contribution of organic carbon retained by iron and aluminum reactive minerals in farmland soils, the amount of organic carbon fixed by the iron and aluminum reactive minerals(OCFe-Al) on the surface layer(0~30 cm), middle layer(30~60 cm), and bottom layer(60~100 cm) of 61 typical farmland soils of different soil types and farming systems in western Chongqing was quantified. The results showed that:OCFe-Al was in the following order:surface layer(mean 2.02 g·kg-1) > middle layer(mean 1.37 g·kg-1) > bottom layer(mean 1.19 g·kg-1), accounting for 12.8%~83.6% of the total soil organic carbon. The average OCFe-Al in the three soil layers was the highest in limestone soils(1.83 g·kg-1) and lowest in purplish soils(1.40 g·kg-1) among different soil types. The paddy-upland rotation crop displayed the highest OCFe-Al(1.65 g·kg-1) in different tillage systems, whereas the uplands had the lowest(1.50 g·kg-1). In terms of terrain, gentle-sloped and flat land had the highest OCFe-Al and steep-sloped land the lowest(1.54, 1.53 g·kg-1, and 0.97 g·kg-1, respectively). The carbon sequestration of iron- and aluminum-bearing reactive minerals was significantly positively correlated with Fe, Al, and soil total organic carbon contents(P<0.01) and negatively correlated with soil pH(P<0.01). In general, the carbon sequestration of iron and aluminum reactive minerals is an important mechanism for soil carbon sequestration and contributes more to the bottom soil carbon pool. Soil type and the farming system will affect the iron and aluminum reactive minerals' ability to fix soil organic carbon. |
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