新疆奇台绿洲不同耕作年限荒漠灰钙土无机碳变化及其影响因素

Variation and influencing factors of desert-sierozem soil inorganic carbon in different tillage years in the Qitai Oasis,Xinjiang,China

荒漠灰钙土是天山北麓地带性土壤,富含碳酸盐和硫酸钙,是优质土地后备资源。本研究采用野外调查取样与室内实验相结合的方法,对新疆奇台绿洲不同耕作年限(<3 a、10 a、20 a、30 a、>40 a)荒漠灰钙土无机碳变化及其影响因素进行分析,探讨了土壤无机碳与土壤理化参数间的关系,特别是石膏对土壤无机碳的增汇作用。结果表明:①耕作层和犁底层的无机碳,对人类活动十分敏感。土壤无机碳随耕作年限先降低后升高,在耕作后的前10 a迅速下降表现为碳源,而后逐渐上升超过初始含量重新转为碳汇,耕作>40 a后土壤无机碳含量较耕作<3 a增加超过10 g·kg^(-1);②土壤无机碳的稳定性同位素δ^(13)C随着耕作年限的增加持续负向偏移,表现出具有截存现代大气CO_(2)的潜力;③荒漠灰钙土中含有极易风化且储量可观的石膏,为次生碳酸盐淀积提供了大量的钙源,这些Ca2+含量决定了研究区土壤无机碳库最终的储量大小。综上说明,富含石膏的荒漠灰钙土耕作后,具有较强的土壤无机碳增汇潜力,重视和准确估算这部分碳增汇潜力有助于我国“双碳”目标的实现。

The soil in the northern piedmont plain of the Tianshan Mountains is desert-sierozem soil,characterized by high levels of carbonate salt and calcium sulfate,is a high-quality land reserve resource.In this study,via field investigations and laboratory experiments,we analyzed the variations of,and factors influencing,soil inorganic carbon in desert-sierozem at different tillage years(<3 a,10 a,20 a,30 a,>40 a)in Qitai Oasis,Xinjiang.The relationship between soil inorganic carbon and soil physical and chemical parameters was discussed,especially,the effect of gypsum on the increase of soil inorganic carbon accumulation.The inorganic carbon in the arable and plow layers was found to be very sensitive to human farming activities.Soil inorganic carbon decreased rapidly after the first 10 a of tillage and then increased with the increase in tillage years,gradually shifting from a carbon source to a carbon sink.After tillage>40 a,the soil inorganic carbon content increased by more than 10 g·kg-1 compared with tillage<3 a.The levels of the stable isotopeδ13C of soil inorganic carbon continued to shift negatively with the increase in tillage years,showing the potential of this land to sequester modern atmospheric CO2.Desert-sierozem contained considerable quantities of easily weatherable gypsum,which provided a large amount of calcium for secondary carbonate deposition;the levels of Ca2+determined the final capacity of the soil inorganic carbon pool in the study area.In summary,gypsum-rich desert-sierozem soil has a strong potential for increasing soil inorganic carbon sequestration after cultivation.Accurately estimating the potential of such carbon sinks will contribute towards achieving China’s“dual-carbon”goal.