塔里木盆地北缘绿洲不同连作年限棉田土壤有机碳、无机碳含量与环境因子的相关性

农田土壤碳库是土壤碳库的重要组成部分,易受人类活动调节且固碳减排潜力巨大,研究土壤有机碳、无机碳含量特征及其与环境因子的关系有助于深入理解土壤生态过程,为全球碳收支平衡研究提供理论支持.本文以塔里木盆地北缘绿洲为靶区,分析土壤碳库特征,结合冗余分析、通径分析,探究土壤有机碳、无机碳含量及其与环境因子的相关关系.结果表明:(1)同一土层不同连作年限棉田土壤有机碳、无机碳含量存在显著差异(P0.05),随连作年限增加,有机碳含量呈先增加后减少趋势,而无机碳含量呈先减少后增加趋势;同一连作年限棉田不同土层土壤有机碳、无机碳含量存在显著差异(P0.05),有机碳含量均在0~20 cm层达到最大值,而无机碳含量均在20~50 cm层达到最大值.(2)通过冗余分析得出环境因子对土壤碳库特征影响的重要性排序为:磷酸酶活性p H值蔗糖酶活性过氧化氢酶活性全氮速效磷速效钾土壤含水量脲酶活性电导率;磷酸酶活性、p H值、蔗糖酶活性、过氧化氢酶活性、全氮、速效磷、速效钾与土壤有机碳、无机碳含量呈极显著相关关系(P0.01);土壤含水量、脲酶活性与土壤有机碳、无机碳含量表现为显著相关(P0.05).(3)通径分析表明,速效钾对有机碳含量直接作用显著,是影响有机碳含量的主要因素,而脲酶活性对无机碳含量直接作用显著,是影响无机碳含量的主要因素.干旱半干旱区土壤有机碳、无机碳含量研究是评价农田生态系统土壤碳的"源/汇"效应的基础数据,对研究全球碳收支平衡和陆地碳循环机制具有重要意义.

Correlation Between Soil Organic and Inorganic Carbon and Environmental Factors in Cotton Fields in Different Continuous Cropping Years in the Oasis of the Northern Tarim Basin

Studying the characteristics of soil organic carbon (SOC) and soil inorganic carbon (SIC), and their relationship with environmental factors is helpful for understanding soil ecological processes, and providing theoretical support for research on the global carbon budget. Based on the oasis in the northern margin of Tarim Basin, this study analyzed the characteristics of the soil carbon pool, and, combined with redundancy and path analyses, explored the relationship between SOC and SIC, and their environmental factors. The results showed that there was a significant difference (P<0.05) in SOC and SIC contents in cotton fields with different continuous cropping years (P<0.05). With an increase in continuous cropping years, the SOC content increased firstly and then decreased, while the SIC content decreased firstly and then increased (P<0.05). The SOC content was the highest in the 0-20 cm layer, while the SIC content was the highest in the 20-50 cm layer. The importance of environmental factors on the characteristics of the soil carbon pool was deduced by redundancy analysis. The order of importance was phosphatase activity > pH > sucrase activity > catalase activity > total N > available P > available K > soil moisture content > urease activity > electrical conductivity (EC); phosphatase activity, pH value, invertase activity, catalase activity, total nitrogen, available phosphorus, and available potassium showed significant correlation with SOC and SIC (P<0.01). Soil moisture and urease activity showed significant correlation with SOC and SIC (P<0.05). The path analysis showed that available P had a direct effect on the SOC content; it was the main factor affecting it. The urease activity had a direct effect on SIC; it was the main factor affecting it. This study of soil carbon pools in arid and semiarid regions is the basis for evaluating the "source/sink" effect of soil carbon in farmland ecosystems, and is of great significance for studying the global carbon budget and land carbon cycle mechanism.