Fertilization and Residue Management Improved Soil Quality of Eucalyptus Plantations

Abstract

The problem of soil degradation caused by continuous planting of Eucalyptus has a long history in southwest China. It is of great significance to explore reasonable management methods to improve soil quality and forest productivity in Eucalyptus plantations. In this study, the third-generation Eucalyptus plantation in the Qipo state-owned forest farm of Shangsi County, Guangxi Autonomous Region, was used as the research object to explore the effects of fertilization and residue management on soil quality. Therefore, a cross-over test between fertilization (In-O, inorganic fertilizer; O, organic fertilizer; M, mixed fertilizer) and residue management (T, residues were tiled; R, residues were removed; S, residues were stacked) was designed. One-way ANOVA was used to detect the difference in each soil indicator between the three fertilization groups or between the three residue management groups, and two-way ANOVA was used to test whether the indicators were affected by the interaction of these two variables. The soil quality of Eucalyptus plantations was evaluated by principal component analysis (PCA) and the minimum data set (MDS). The results showed that inorganic fertilizer significantly increased the soil nutrient content, such as N, P and K, while organic fertilizer significantly increased soil enzyme activity. Compared with Group R, the retention of residues (T, S) improved the soil pore structure and promoted soil biochemical reactions. The order of soil quality indexing (SQI) was O × T (0.697) > M × T (0.618) > In-O × T (0.557) > O × S (0.490) > M × S (0.439) > O × R (0.362) > In-O × S (0.324) > M × R (0.290) > In-O × R (0.138). Fertilization, residue management and their interaction had significant effects on the soil quality index; among them, residue management was the main factor in the variation of SQI, with a variance contribution rate of 41.6%. In the management of Eucalyptus plantations, soil quality can be improved by applying organic fertilizer and tiling plant residues.