长期梨树种植土壤团聚体组成及有机碳分布特征

为探究长期梨树种植土壤团聚体结构及其对土壤有机碳的影响，以砀山县良梨镇共12个年限的梨树土壤为研究对象，以果园附近农田土壤为对照，分析不同梨树种植年限土壤(0～20 cm)的团聚体粒级分布、土壤及各团聚体组分有机碳含量的动态特征。研究结果表明：随着种植年限的增加，土壤大团聚体(>0.25 mm)含量呈先上升后略有下降并趋于稳定的趋势，种植150 a处取得最大值达到798.8 g/kg。梨园土壤总有机碳含量、大团聚体有机碳含量相较对照农田土壤显著提高(P<0.05)，分别提高了1.45倍和2.24倍，而微团聚体(<0.25mm)有机碳含量显著下降。各个年限梨园土壤有机碳主要由大团聚体贡献，贡献率为68.06%～98.78%，相较农田土壤(39.76%)贡献率提高28.3%～59.02%；微团聚体的贡献率随着年限的增加而下降，表明梨园的长期种植促使有机碳从微团聚体向大团聚体分配。土壤大团聚体含量与有机碳含量呈极显著正相关(P<0.01)，均随着种植年限的增加先上升后下降至稳定趋势。表明梨园种植有利于改善土壤结构，增加土壤的固碳潜力。

Aggregate Composition and Organic Carbon Distribution in Long-term Pear Planting Soil

In order to explore aggregate structure of long-term pear planting soil and its effect on soil organic carbon, pear planting soils in Liangli Town, Dangshan County, which has a total of 12 years from 10 to 300 years, were used as the research object, and the farmland soil near pear orchard was used as a control. Soil aggregate size distribution (0-20 cm), organic carbon contents in soils and aggregates were studied in order to explore the correlation between soil aggregates and organic carbon for long-term pear planting. The results showed that with the increase of planting years, the content of soil macro-aggregates (>0.25 mm) increased first, then decreased slightly and tended to stabilize, reached a maximum value (798.8 g/kg) in 150 years. The contents of soil total organic carbon and organic carbon of macro-aggregates significantly increased by 1.45 times and 2.24 times respectively compared with the control (P<0.05), while organic carbon content of micro-aggregates (<0.25 mm) decreased significantly. Soil organic carbon was mainly contributed by large aggregates, with the contribution rate of 68.06%-98.78%, which was 28.3%-59.02% higher than that of control (39.76%). The contribution rate of micro-aggregate decreased with year, indicating that the long-term pear planting promoted the distribution of organic carbon from micro-aggregate to macro-aggregate. There was a significant positive correlation between the contents of macro-aggregates and organic carbon (P<0.01), and they all increased first and then decreased to a stable trend with year. It shows that pear planting is beneficial to improve soil structure and increase carbon sequestration potential of the soil.