不同恢复年限对土壤有机碳组分及团聚体稳定性的影响

EFFECTS OF RECLAMATION HISTORY OF DESERTED SALINIZED FARMLANDS ON ORGANIC CARBON COMPOSITION AND AGGREGATE STABILITY OF THE SOILS

通过干旱区典型内陆河玛纳斯河流域绿洲田间定位实验，研究了盐渍化弃耕地不同复垦年限对土壤活性有机碳组分及对团聚体稳定性的影响。结果表明，恢复初期降低了土壤微生物生物量碳（MBC）和易氧化有机碳（LOC）的含量，降低幅度小。随着恢复年限的增加，土壤有机碳（SOC）含量增加，显著提高了土壤MBC和LOC的含量以及土壤水溶性有机碳（WSOC）和土壤热水溶性有机碳（HWSOC）的含量和分配比例，其中恢复1年、5年和10年的土壤HWSOC分别较弃耕地高61．04％、143．5％和152．4％。连续人工种植后SOC和大团聚体（〉0．25mm）含量增加，土壤团聚体稳定性增强，其中恢复10年0～5cm、5～10cm土层〉0．25mm团聚体占57．30％和56．50％，团粒指数下降至43．00％。相关分析表明，〉0．25mm水稳性团聚体的含量与土壤有机碳（SOC）和土壤HWSOC达到显著正相关，干旱区盐渍化绿洲农田土壤HWSOC对维持土壤团聚体稳定性的贡献明显。

A stationary field experiment was conducted in an oasis along the Manas River, which is a typical inland river in the arid region of Northwest China to study effects of reclamation history of deserted salinized farmlands on labile organic carbon composition and aggregate stability of the soils. Results show that soil microbial biomass C （MBC） and soil labile carbon （LOC） decreased somewhat in content in the first years after the reclamation. And then soil organic carbon （ SOC ）, especially MBC and LOC, increased in content and soil water soluble organic carbon （ WSOC ） and hot-water sol- uble organic carbon （HWSOC） in content and in proportion as well, in the years that followed. In the 1st, 5th, and 10th year after the reclamation, soil hot-water soluble organic carbon （HWSOC） in the field was 61.04% , 143.5% and 132.4% , respectively, higher than that in the control. After years of continuous cultivation, SOC and soil maeroaggregate （ 〉0.25 mm） increased in content and the latter in stability, too. In the field 10 years old in reclamation history, soil ag- gregate （ 〉0.25 mm） accounted for 57.30% and 56.50% , respectively, in the 0 -5 cm and 5 - 10 em soil layer, but the aggregate index decreased to 43.00%. Correlation analysis shows that the content of soil water-stable aggregate （ 〉 0.25 mm ） was significantly positively related to SOC and HWSOC and the contribution of the latter is significant to main- taining the stability of soil aggregates in salinized oasis farm fields in the arid region.