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| Effect of Ammonium Sulfate Application on CO2 Emissions from Four Different Soils in Loess Plateau |
| Received:January 25, 2015 |
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| KeyWord:soil type;carbon emission;sterilization;inorganic carbon;mineral nitrogen;soil pH |
| Author Name | Affiliation | E-mail | | MENG Yan | College of Natural Resource and Environment, Northwest A&F University, Yangling 712100, China
Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling 712100, China | | | CAI Miao | College of Natural Resource and Environment, Northwest A&F University, Yangling 712100, China
Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling 712100, China | | | SHI Qian-yun | College of Natural Resource and Environment, Northwest A&F University, Yangling 712100, China
Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling 712100, China | | | ZHOU Jian-bin | College of Natural Resource and Environment, Northwest A&F University, Yangling 712100, China
Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling 712100, China | jbzhou@nwsuaf.edu.cn |
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| Abstract: |
| Large emissions of greenhouse gases have caused the global temperature increase. CO2 is one of the most important greenhouse gases. Calcareous soils are rich in calcium carbonate, which may release CO2. Soil pH and calcium carbonate content are often deemed to be important factors controlling soil inorganic carbon turnover. Here airtight culture method was adopted to evaluate the role of applying ammonium sulfate[(NH4)2SO4] fertilizer on CO2 emissions from four different calcareous soils from Loess Plateau. These soils are Lou soil, dark loessial soil, loessial soil and aeolian sandy soil varying in SOM, pH, texture and carbonate content. The soils were incubated under closed-jar conditions for 46 days at 25 ℃with and without 1000 mg·kg-1 mercury chloride(HgCl2) buffered by piperazine-1,4-bisethanesulfonic acid(PIPES). Under non-sterilized condition,(NH4)2SO4 application decreased soil pH and NH4+ content. However, sterilization effectively inhibited the nitrification process, thus alleviating soil pH reduction and resulting in NH4+ accumulations in soil. After 46 days of incubation, applying (NH4)2SO4 funder non-sterilized condition increased CO2 emissions by 26.9%, 19.5%, 68.8% and 46.1% for Lou soil, dark loessial soil, loessial soil, and aeolian sandy soil, respectively, compared to control soils(no fertilization). Sterilization obviously decreased CO2 releases, implying restrained soil organic mineralization. However,(NH4)2SO4 treatments still increased CO2 emissions from four sterilized soils by average 25.5% in comparison to no(NH4)2SO4 soils. Our results suggest that the main mechanism for CaCO3 dissolution was protons produced by nitrification under non-sterilized condition, while it was H2SO4 under sterilized conditions. The partial pressure of soil solution might also leads to release of CO2. Our study confirmed that CO2 released from calcareous soil during the incubation may be from both soil organic carbon and soil inorganic carbon. Ignoring this inorganic process would result in overestimation of mineralization of soil organic carbon. |
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