【目的】东北黑土区是我国重要的商品粮生产基地,长期传统机械作业破坏土壤结构、降低土壤团聚体稳定性,加剧了土壤侵蚀和退化。探讨外源有机物料添加对农田黑土团聚体稳定性的影响,为侵蚀退化黑土的修复提供依据。【方法】以东北黑土区开垦60 a的耕地土壤为研究对象,设计3种常见有机物料(生物炭、秸秆、猪粪肥)、3个添加量梯度[少量(常规量的50%)、实际还田量(常规量的10%)、大量(常规量的200%)]的室内恒温恒湿培养实验,采用恒质量补充水分法置于25 ℃的培养箱中培养180 d。利用 Le Bissonnais 法的3种团聚体破坏机制[快速湿润(FW)、慢速湿润(SW)和预湿润后振动(WS)]模拟暴雨/大雨、小雨和径流冲刷的田间环境条件,以此来探究不同降雨条件下土壤团聚体组成及稳定性对各种类和添加量有机物料的响应差异。【结果】①3种破坏机制中,添加少量、实际还田量及大量的生物炭、秸秆、猪粪肥均能增加土壤大团聚体含量、增大平均质量直径(MWD)、减小团聚体破坏率(PAD)进而提高其稳定性,但是作用效果不同:FW机制下少量添加时,添加生物炭改善团聚体的效果最好,实际还田量和大量添加时,添加秸秆效果更佳;SW机制下少量添加时,添加猪粪肥作用效果最优,实际还田量和大量添加时,添加秸秆效果最好;WS机制下各添加量均以添加猪粪肥改善土壤团聚体的作用效果最佳。②添加外源有机物料未改变土壤团聚体破碎机制,FW的崩解作用为主导因素,其次是WS的机械分解作用,SW的黏粒膨胀作用对团聚体的破坏作用最小。【结论】总体而言,在暴雨/大雨、小雨和径流冲刷的田间环境条件下,添加生物炭、秸秆、猪粪肥均能不同程度改善土壤团聚体状况,提高土壤抗蚀能力,有效修复退化黑土;综合考虑黑土区自然条件和物料成本,以猪粪肥改良黑土的效果相对更优。

【Objective】The black soil region of northeast China is an important commercial grain production base in China, however, long-term traditional mechanical production has destroyed the soil structure and decreased aggregate stability, intensifying soil erosion and degradation. The aim of this study is to determine the effects of exogenous organic materials on the aggregate stability of farmland black soil and provide a basis for the restoration of eroded and degraded black soil.【Method】A constant temperature-humidity culture experiment was conducted by adding three kinds of exogenous organic materials (straw, biochar and swine manure) with different content gradients (small, actual returning and large amounts) to black soil cultivated for 60 years in northeast China, and the constant mass-supplementation water method was used in a 25 ℃ incubator for 180 days. Soil aggregate distributions and stability differences caused by three aggregate disintegration mechanisms [fast wetting (FW), slow wetting (SW) and wet stirring (WS)] were compared using the Le Bissonnais method for different types and amounts of organic materials. FW, SW and WS based on the Le Bissonnais method, were adopted to simulate the field environmental conditions of rainstorms, heavy and light rain, and runoff, respectively.【Result】(1) The three disintegration mechanisms of adding small, actual returning and large amounts of biochar, straw and swine manure could significantly improve soil aggregate stability by increasing large aggregate proportion, improving the average weight diameter (MWD) and reducing the percentage of aggregate destruction (PAD); however, improvement efficiency differed: for FW, adding biochar in small amounts and straw in actual returning and large amounts was the best; for SW, adding swine manure in small amounts and straw in actual returning and large amounts was the best; for WS, adding swine manure in any amount was always the best.(2) Exogenous organic materials cannot change the aggregate disintegration mechanisms; FW disintegration was the predominant mechanism, followed by the mechanical disintegration of WS, and SW mechanical disintegration characterized by clay expansion had the least destructive effect on aggregates.【Conclusion】During the field environmental conditions of rainstorms or heavy as well as light rain, runoff, biochar, straw and swine manure can improve soil aggregate stability and anti-erodibility to different degrees, effectively restoring degraded black soil. Considering the natural conditions and material capitalized costs, swine manure was most appropriate for black soil restoration.