开垦年限对干旱区土壤理化性质及剖面无机碳的影响

为阐明开垦年限对土壤理化性质及无机碳的影响,进一步了解干旱区土地开垦进程中的土壤质量变化规律和碳吸收与存储过程,以开垦年限分明的典型区—新疆三工河流域阜北农场为研究区,调查、分析了不同开垦年限(已开垦0,1,3,5,15,30,50a)剖面土壤的pH值、盐分、无机碳含量与储量的分布特征、变化规律及开垦年限对它们的影响。结果表明:(1)已开垦土地的土壤pH值随土层深度的增加而升高;随开垦年限的延长,0—60cm(耕作层)的土壤pH值显著降低(P0.05),60—140,140—200cm土壤pH值则升高。不同开垦年限的土壤盐分在剖面上呈"S"型分布,研究区土壤盐分为表聚型;随着开垦年限的延长,土壤盐分聚集层逐渐下移,各剖面平均含盐量减少。开垦历史的延长,有助于排盐排碱。(2)不同开垦年限的土壤无机碳含量与储量:0—60cm显著低于60—140cm,60—140cm显著低于140—200cm(P0.05)。随着土层深度的增加,土壤无机碳储量占全碳的比例增大。随着开垦年限的延长,0—60cm耕作层土壤无机碳含量、储量呈"减少—增加—减少"的变化趋势,无机碳储量占全碳的比例减少。与原始荒地相比,开垦50a时,0—60cm耕作层的土壤无机碳储量减少了55%;0—200cm土壤无机碳储量增加了11.74kg/m~2,无机碳储量所占全碳的比例降低了1.28%。(3)开垦年限的延长对土壤pH、盐分及无机碳的显著影响深度不同,分别集中于0—60cm耕作层,0—140cm及整个研究深度范围内。

Effect of Land Reclamation Age on Soil Physicochemical Properties and Inorganic Carbon in Aarid Areas

To understand variations in soil properties and the process of carbon uptake and store in arid areas under land reclamation interference, this paper was mainly through exploring the impact of reclamation age on physicochemical properties and soil inorganic carbon (SIC) in a depth of 0-200 cm soil profiles. Fubei farm of Sangong river catchment, a typical region with different reclamation history lands in Xinjiang province, was act as the study area. Soil profiles of lands in different reclamation years were used to analyze the variation of soil pH values, soil salt content and SIC. Our results showed that: (1)Soil pH enhanced with the increase of soil depth in farm lands. Besides, as the reclamation age extension, it was significantly decreased in 0-60 cm (P<0.05) but increased in 60-140 cm and 140-200 cm soil profiles. Soil salinity was accumulated in top soils that salt content distributed as a type of "S" in soil profiles. With the reclamation age extending, the accumulation layer of soil salt went down gradually and the average value of salt content in each section decreased. It indicated that the extension of cultivation history contributed to moving salt and alkali. (2)The values of SIC content and storage in 0-60 cm were significant less than those in 60-140 cm (P<0.05) and those in 140-200 cm soil profile (P<0.05). The percentage of SIC ascended in vertical direction. SIC content, SIC storage and the percentage of SIC in 0-60 cm increased after first decreased and then decreased again with the reclamation age extending. Comparing with that in original lands, SIC storage in 0-60 cm of fifty years reclamation age decreased by 55% and that in 0-200 cm increased by 11.74 kg/m2 and the percentage of SIC also decreased by 1.28%. (3)The significantly influence of reclamation age on soil pH, salt and SIC were in different soil depth, respectively, in 0-60 cm, 0-140 cm and 0-200 cm.