Soil compaction by farm machinery may persist for decades, hampering soil productivity and functioning. Assessing compaction costs and guiding recovery strategies are hindered by paucity of data on soil structure recovery rates. A long-term Soil Structure Observatory was established on a loamy soil in Switzerland to monitor soil structure recovery after prescribed compaction, and to better assess the roles of natural processes (vegetation, macrofauna, and shrink–swell cycles) on recovery patterns. The aim of this study was to quantify short-term soil structure recovery under natural conditions in the presence and absence of plant cover (ley and bare soil). We measured soil porosity and gas and water transport capabilities at 0.1 and 0.3 m depth. Two years after the compaction event, soil physical properties have not recovered to precompaction levels, even within the topsoil. Surprisingly, no differences were observed in the recovery patterns of ley and bare soil treatments. Measurements show that recovery rates differ among soil properties with the most severely affected properties by compaction (permeability) exhibiting highest recovery rates. Total soil porosity shows no recovery trend, suggesting lack of soil decompaction. Improved soil functions and decompaction are distinct aspects of soil structure recovery, with the latter requiring net upward transport of soil mass. We suggest that soil structure recovery proceeds at two fronts: from the soil surface downward, and expanding around local biologically-active pockets (marked by biopores) into the compacted soil volumes. This concept could be tested with additional data of longer time series at our site as well as in other soils and climates.

中文翻译：

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压实后土壤结构恢复：壤土中土壤物理性质的短期演变

农业机械造成的土壤压实可能会持续数十年，从而阻碍土壤生产力和功能。由于缺乏土壤结构恢复率的数据，评估压实成本和指导恢复策略受到阻碍。在瑞士的肥沃土壤上建立了一个长期土壤结构观测站，以监测规定压实后土壤结构的恢复情况，并更好地评估自然过程（植被、大型动物和收缩-膨胀循环）对恢复模式的作用。本研究的目的是量化自然条件下在有和没有植物覆盖（麦地和裸土）的情况下的短期土壤结构恢复。我们测量了 0.1 和 0.3 m 深度的土壤孔隙度以及气体和水的输送能力。压实事件两年后，即使在表土中，土壤物理特性也没有恢复到预压实水平。令人惊讶的是，在麦地和裸土处理的恢复模式中没有观察到差异。测量表明，不同土壤性质的恢复率不同，受压实（渗透性）影响最严重的性质表现出最高的恢复率。土壤总孔隙度没有恢复趋势，表明土壤没有分解。改善土壤功能和分解是土壤结构恢复的不同方面，后者需要土壤质量的净向上传输。我们建议土壤结构恢复在两个方面进行：从土壤表面向下，并在局部生物活性口袋（以生物孔为标志）周围扩展到压实的土壤体积。