Abstract—

Soil formation on the human time scale is immensely time consuming, although it can be significantly accelerated through the effects of vegetation. The content of water-stable aggregates (WSAs) is a useful indicator for determining both the soil development level and the soil quality. However, in severely degraded soils, especially in the Baltic pedoclimatic region, the effects of vegetation on the aggregate stability have been poorly studied. Therefore, to obtain more knowledge about the impact of vegetation on WSA, and thereby knowing how to improve it, this study was conducted on a long-term soil formation experiment in Estonia near Tartu. In 1964, the initial soil from an area of 20 × 8 m down to 100 cm depth was replaced with a sandy loam calcareous glacial till. The experiment started on April 26, 1965, when plants were sown on the plot. The topsoil (0–20 cm) samples were analyzed in 1966, 2000, 2007, and 2014. The study indicated that perennial grasses (meadow fescue and common meadow-grass) fertilized with P₄₀K₇₅, compared to N₁₅₀P₄₀K₇₅, decreased the WSA content, as well at the accumulation rate of soil organic carbon (SOC) and the total nitrogen content (N_tot). The hybrid alfalfa treatment resulted in the significantly highest SOC and N_tot accumulation, but not in the overall highest WSA content. Under barley, manure positively affected the WSA and SOC, though many other physical properties were not improved. Compared to the initial till under bare fallow, the SOC and N_tot contents were significantly higher under grown crops, but the WSA content remained the same. In addition, regardless of the grown crops, the WSA of larger (0.25–2 mm) aggregates was substantially higher than that of smaller (0.25–1 mm) aggregates. Also, as the relationship between WSA and SOC in the study was linear, the soil was far from C saturation and still in development. Overall, it can be concluded that the cultivation of perennial grasses and hybrid alfalfa on the severely eroded soil is the most rational option to improve the water stability of aggregates and increase the SOC and N_tot contents. However, because of the complexity of the aggregation process, further research is still needed.

中文翻译：

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钙质冰川耕作50年土壤形成试验中土壤团聚体的水稳定性

摘要-

尽管可以通过植被的作用大大加速土壤形成，但在人类时间尺度上却非常耗时。耐水骨料（WSA）的含量是确定土壤发育水平和土壤质量的有用指标。然而，在严重退化的土壤中，尤其是在波罗的海的古气候区域，植被对集聚体稳定性的影响研究很少。因此，为了获得有关植被对WSA的影响的更多知识，从而知道如何改善WSA，本研究是在塔尔图附近的爱沙尼亚进行的一项长期土壤形成实验。1964年，最初的土壤从20×8 m的区域下降到100 cm深度，被砂壤性钙质冰川土所代替。该实验始于1965年4月26日，当时在该地块上播种了植物。₄₀ ķ ₇₅相比，到N ₁₅₀ P ₄₀ ķ ₇₅时，WSA内容，以及在土壤有机碳（SOC）和总氮含量（N的累积率降低_TOT）。混合苜蓿处理导致SOC和N _tot积累显着最高，但总体WSA含量最高。在大麦下，粪肥对WSA和SOC产生了积极影响，尽管许多其他物理性能没有改善。与初始休耕相比，SOC和N _tot种植的农作物中的含量明显更高，但WSA含量保持不变。此外，无论种植哪种作物，较大（0.25-2 mm）骨料的WSA均明显高于较小（0.25-1 mm）骨料的WSA。另外，由于研究中WSA和SOC之间的关系是线性的，因此土壤远未达到C饱和，并且仍在发育中。总体而言，可以得出结论，多年生牧草和混合苜蓿对严重侵蚀土壤的培育是提高聚集体的水稳定性和提高SOC和N最合理的选择_TOT内容。但是，由于聚合过程的复杂性，仍需要进一步的研究。