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Urban greening produces a large amount of garden waste, and the pyrolysis of garden waste into biochar is an effective waste management technology. Biochar has a large specific surface area and soil remediation ability. However, the knowledge about the co-recycling of sewage sludge and garden waste biochar to improve the growth of Monstera deliciosa needs to be highlighted. Therefore, we conducted a pot experiment by applying Ficus altissima litter-derived biochar (FB) at rates of 0, 1.5, and 3.0% (w/w, CK, FB1.5, and FB3) in soil amended with sewage sludge at 50% (w/w), to improve the soil properties, and further analyzed the effects of FB on growth and heavy metals (HMs) uptake of landscape plant M. deliciosa. Results showed in comparison with control setups, the addition of 3% FB treatment in sewage sludge amended soil improved the soil properties and significantly increased M. deliciosa dry weight (86.75%), root: shoot ratio (73.23%), N (99.44%), P (116.13%), K (124.40%), Pb (78.81%), and Cu (159.01%) accumulation respectively. In summary, FB3 treatment achieved the best effects in promoting plant growth and soil remediation. These findings revealed that sewage sludge and garden waste biochar could be recycled as amendments for poor acid soils under restoration, a sustainable development path for urban waste disposal.

Vegetation succession can change the function and quality of the soil. Exploring the changes in soil properties during secondary forest restoration is of great significance to promote forest restoration and improve the ecological service function of subtropical ecosystems in South China. In this study, we chose three typical forests in subtropical China as restoration sequences, broadleaf–conifer mixed forest (EF), broad-leaved forest (MF), and old-growth forest (LF), to study the changes in soil physico-chemical and biological properties and the changes of soil comprehensive quality during the secondary succession of subtropical forest. The results showed that the soil physical structure was optimized with the progress of forest succession. The soil bulk density decreased gradually with the progress of forest restoration, which was significantly affected by soil organic carbon (p

Phosphorus (P) is the primary factor limiting soil organic matter (SOM) decomposition and carbon (C) storage in the tropical P-deficient plantations. However, the mineralization of SOM derived from N-fixing and non-N-fixing plantations may respond differently to P addition within the laboratoryor field-based incubation experiment. In this study, the effects of P addition (+P) combined with glucose (+Glu) on soil N mineralization within Eucalyptus urophylla (EU) and Acacia auriculiformis (AA) plantations were evaluated using a 60-d laboratory aerobic incubation assay in subtropical China. The results showed that Glu addition significantly affected the net N mineralization and nitrification in both EU and AA plantations. In the 7th day incubation, +Glu treatment enhanced the N mineralization, whereas +Glu+P dramatically accelerated the N immobilization in EU plantation. However, +Glu+P treatment increased N mineralization while +Glu enhanced N immobilization in AA plantation, suggesting that P addition greatly affected the direction of N transformation within different plantations under the labile C input in the early stage of incubation. However, in the 15th day incubation, +Glu increased while +Glu+P greatly reduced the N immobilization in EU plantation. On the contrary, +Glu promoted while +Glu+P further accelerated the N immobilization in AA plantations, indicating that P addition had the contrasting effects on N immobilization within EU and AA plantations. After the 15th day incubation, Glu addition further facilitated the N immobilization in two plantations. Although +Glu increased the fungi and bacteria PLFA biomass, +Glu+P significantly increased F/B ratios, which may contribute to the direction and magnitude of N transformations in two plantations. However, in these two plantation forests with low soil P availability, single P addition would not significantly alter the N mineralization mediated by microbe in the laboratory incubation experiment without the labile C input. Therefore, the significant effects of P addition on the N mineralization or immobilization varied with the incubation stage and plantation types. We recommend that the P availability has profound implications on SOM decomposition and C sequestration in subtropical plantations. [ABSTRACT FROM AUTHOR]