不同年限土地整治土壤碳分布特征

Effects of Different Land Renovation Years on Soil Carbon Fixation

为明晰土地整治年限对土壤碳固持的影响,进一步探索土地整治工程对土壤质量及碳吸收与存储的影响规律,以陕西省已开展沙地、盐碱地、废弃宅基地3类土地整治项目为例开展本研究,结果表明:风沙地整治能有效增加土壤碳含量,碳密度和碳含量的变化较为一致,在整治初期因工程措施的扰动,风沙地表层有机碳降低,但因作物收获需求表层无机碳增高,随着种植年限的增长,整治后6年,沙地总碳、有机碳、无机碳密度则比整治前和整治2年后都呈显著上升趋势,各土层增幅都在30%以上;废弃宅基地整治前土壤质量较好,整治前后土壤碳含量的变化不显著,但随着种植年限的延长,整治7年后,总碳密度在0—10,10—20 cm处分别增高40%,34%;有机碳密度在0—10 cm,10—20 cm处分别增高83%,53%,碳储量随整治年限逐渐增加;盐碱地整治后表层覆沙中富含碳酸盐,随着碳酸盐向深层淋溶,深层无机碳增加,随着种植年限的增加,表层无机碳含量显著增加,剖面无机碳储量也显著增加,有机碳储量波动不大,总碳储量显著增高。风沙地、废弃宅基地、盐碱地整治对于土壤碳固持能力都有一定改善作用,且这种作用在作物种植与工程措施实施两方面的综合效应下,会随着整治年限的延长,更加明显。

In order to analyze the impact of land consolidation on soil carbon sequestration and further explore the impact of land remediation projects on soil quality and carbon sequestration and storage, we took three types of land remediation projects such as sandy land, saline-alkaline land and abandoned housing sites as the examples. The results of this study showed that the improvement of soil carbon content in windy sandy land remediation could effectively increase the carbon density and carbon content. In the initial stage of remediation, due to disturbance of engineering measures, the organic carbon in the surface layer of sandy land decreased;but due to the crop harvesting demand, surface inorganic carbon increased with the increase in the number of years of cultivation, the total carbon, organic carbon, and inorganic carbon density in the sandy land were significantly higher than those before the remediation and two years after the remediation, and the growth of all soil layers was more than 30%. The quality of soil before treatment of abandoned housing plots was good, and the soil carbon content did not change significantly before and after remediation, but with the extension of planting years, the total carbon density increased by 40% in 0—10 cm layer and 34% in 10—20 cm layer after 7 years of remediation;organic carbon density increased by 83% and 53% in 0—10 cm layer and 10—20 cm layer, respectively, and carbon storage gradually increased with the years of remediation;carbon enrichment in surface sedimentation after saline-alkali soil remediation salts, as carbonates leached towards the deeper layers, inorganic carbons increased in deeper layers. With the increase of planting years, the surface inorganic carbon content increased significantly, the profile inorganic carbon reserves also increased significantly, the organic carbon reserves fluctuated little, and the total carbon reserves significantly increased. The wind-sand, abandoned homestead, and saline-alkali land remediation have a certain improvement effect on soil carbon retentive capacity, and the effect will be more obvious with the extension of the remediation period under the combined effects of crop planting and engineering measures.