Effects of Non-burning Management on Soil Aggregate Nutrients and Stability in Eucalyptus Plantations

  Objective  Burning, as a traditional land preparation method, is accelerating soil nutrients loss and soil compaction in Eucalyptus plantations in southern China. Oppositely, replacing burning with non-burning can improve the growth environment of Eucalyptus and can have a positive impact on soil nutrients and structure. However, from the perspective of soil aggregates, the reasons for improving soil structure and nutrients content in Eucalyptus plantations with non-burning management remain unclear and need to be further explored.

  Method  In this study, Eucalyptus plantations after 2-year burning and retaining logging residues were selected as the research objects, and the local evergreen broad-leaved forest was used as the control. The average diameter at breast height, average tree height and volume of Eucalyptus under two different afforestation modes were investigated, and the particle size distribution of soil aggregates (> 2 mm, 2-0.25 mm, 0.25-0.053 mm and < 0.053 mm), the contents of organic carbon, total nitrogen, and total phosphorus in all stands were further determined.

  Result  Compared with burning, non-burning significantly promoted soil aggregation and increased the contents of organic carbon, total nitrogen and total phosphorus in aggregates of all different sizes. Correlation analysis showed that total nitrogen and total phosphorus in soil aggregates across 2-0.25 mm and 0.25-0.053 mm were significantly correlated with mean weight diameter and geometric mean diameter of aggregates. Principal component analysis and linear regression analysis showed that the soil aggregate stability was significantly positively correlated with the average diameter at breast height, average tree height and volume of Eucalyptus. Additionally, the soil aggregate stability of non-burning had far exceeded that of the traditional burning in two years, but in the surface soil it still could not reach the level of evergreen broad-leaved forest in the short term.

  Conclusion  Non-burning can improve the contents of organic carbon, total nitrogen and total phosphorus of soil aggregates in Eucalyptus plantations. It can also improve the soil aggregate stability, and ultimately has a positive impact on the growth of Eucalyptus. The results can provide a theoretical basis for strengthening the management and utilization of logging residues in the sustainable management of Eucalyptus plantations.