长期梨树种植土壤团聚体组成及有机碳分布特征

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

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(<0.25 mm)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。

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.