Impacts of different ecological types of earthworm on aggregate distribution and stability in typical latosolic red and red soils

Objective  To comprehensively analyze the effects of different ecological types of earthworm on soil aggregate distribution, water stability of aggregate and percentage of aggregate disruption (PAD) in South China, and provide scientific basis and theoretical support for utilizing earthworms to improve soil structure.

Method  The laboratory culture experiment was carried out in this study. Eisenia fetida, Pontoscolex corethrurus, Amynthas robustus and A. aspergillum were added in typical latosolic red soil and red soil in South China to study the impacts of different ecological species of earthworm on soil structure.

Result  Compared with the blank control, the addition of P. corethrurus, A. robustus and A. aspergillum significantly promoted the formation of large-aggregates (d > 2 000 μm) in two soil types ( P < 0.05), The large-aggregate proportion in latosolic red soil increased respectively by 35.20%, 44.81% and 37.88%, and increased respectively by 14.92%, 25.31% and 20.18% in red soil. A. robustus significantly reduced the contents of water stable large-aggregates (d > 2 000 μm) and small-aggregates (250 μm≤ d≤2 000 μm) in latosolic red soil, but significantly increased the proportion of water stable micro-aggregates (d < 250 μm, P < 0.05), which was 37.84% higher than that of the blank control. The addition of four types of earthworms significantly increased PAD values in both two soil types ( P < 0.05), and the PAD value in adding A. aspergillum treatment was the lowest. The results of principal component analysis showed that there were significant differences in the distributions and stabilities of soil aggregates under the action of different earthworms in two different soils (P < 0.05).

Conclusion  The impacts of different earthworm types in South China on latosolic red soil and red soil aggregate distribution and stability are different. The endogenic earthworm (P. corethrurus and A. robustus) has the best impact on the improvement of soil structure. The endo-anecic (A. aspergillum) had the least destructive impact on water stable soil aggregate.