This study uses the tree stumps of the three representative trees in Taiwan (Leucaena leucocephala, Syzygium samarangense, and Ziziphus jujuba) as the material source and recyclable oyster shell powder as an activator. A carbonization process for upgrading and recycling the tree stumps was developed with our homemade, digital-controlled, energy-saving carbonization system. First, the tree stumps are carbonized at a medium temperature of 500 °C and then heated to 900 °C for high-temperature carbonization, followed by the activation procedure as required. With our method, we can produce biochar with a high proportion of fixed carbon and a high proportion of meso- and macropores while maximizing the yield of wood vinegar. The specific surface area of the meso- and macropores can reach up to 70 m²/g or more. The effect of different activation materials on the pore characteristics and specific surface area of biochar was carefully examined. It was found that both KOH and oyster shell powder is the ideal activator for producing biochar with a high proportion of meso- and macropores. The FTIR spectrum, CEC, and contents of the ordinary elements and heavy metals of the biochar were also reported. It is clear from the FTIR data that the absorption peaks of the overall spectrum of the three types of biochar after carbonization at high temperature are cleaner than those of biochar carbonized at low temperature. This research can promote the recycling of agricultural residues, enhance soil carbon sequestration, preserve fertilizers, and suppress diseases and pests, moving towards approaching the goal of net-zero carbon emissions.

To develop composite materials of biochar micro-coated soil beneficial microorganisms, soil samples were collected from the saline-alkali land of the Penghu in Taiwan. After isolation, purification and identification, a total of one Bacillus amyloliquefaciens and two Bacillus megaterium were identified as the source of beneficial microorganisms. The agricultural waste is collected and initially crushed, and then made into biochar through a series of thermal cracking processes. The specific surface area of biochar is more than 100 m²/g, the fixed carbon is more than 80%, the proportion of medium and large pores is more than 30%, the pH after adjustment is 7.3 ± 0.2, and the pore size of beneficial microorganisms grows inward, which is one of the beneficial microorganisms. The biochar micro-coated soil-beneficial microorganism composite material developed in this experiment can indeed help crops to overcome the stress of salt damage to a certain extent, and Bacillus amyloliquefaciens can indeed promote plant growth and help crops effects of over-salting adversity.

T he objective of this study was to investigate the chlorine-related challenges in Automotive Shredder Residue (ASR) by developing a de-chlorination strategy and formulating Solid Recovered Fuel (SRF) pellets with improved environmental and fuel quality. A ternary blending approach was employed using Fe–Ca-based inorganic dechlorinating agents and thorny bamboo biomass as co-materials with ASR. The de-chlorination efficiency, calorific value, and ash content of the resulting SRF were evaluated. Results indicated that the optimal dechlorinating formulation reduced the chlorine content of PVC from 43.26 wt% to 0.59 wt%, achieving a de-chlorination efficiency of 97.23%. A second-order polynomial regression model （ η_DeCl = –1.5277x² + 2.5519x – 0.0225 ， R² = 0.9347 ） was developed to predict the de-chlorination performance based on the blending ratio of dechlorinating agent to ASR, demonstrating behavior consistent with first-order reaction kinetics observed in pyrolytic de-chlorination. The final ternary formulation—comprising 55% thorny bamboo, 37.5% ASR, and 7.5% dechlorinating agent—produced SRF pellets with improved overall quality, demonstrating effective chlorine control, reasonable ash content, and enhanced thermal properties suitable for regulatory compliance and practical application. S uch findings meet the criteria set by EN ISO 21640:2021 (Class 2), JIS Z7311 (Grade A), and forthcoming Taiwanese SRF regulations. B ased on the findings in this work it can be stated that the high de-chlorination potential of Fe–Ca-based additives for chlorine-rich waste and introduces a predictive formulation model that supports both resource circularity and clean fuel production.

The authors would like to make the following corrections about the published paper

Increasing fertilizer costs, climate-related stresses, and soil degradation caused by the prolonged use of chemical fertilizers threaten the sustainability of agricultural production. Organic soil amendments offer a promising approach to restoring soil health while reducing dependence on synthetic inputs. This study evaluated the combined effects of biochar and organic fertilizer on soil health and soybean (Glycine max L.) productivity under acidic soil conditions. During the 2024 growing season, a greenhouse pot experiment was conducted using a completely randomized design (CRD) comprising seven treatments. Each treatment was replicated three times, resulting in a total of 21 pots. The treatments consisted of different combinations of biochar (B) and organic fertilizer (F), applied at rates of grams per 10.5 kg of soil: control (B0F0), B35F70, B35F105, B35F140, B70F70, B70F105, and B70F140. Treatment means were compared using the Least Significant Difference (LSD) test at p < 0.05. The results showed that the highest soil pH value (5.41) was recorded under the B35F70 treatment at 45 days after amendment of the acidic soil. Application of the B35F140 treatment resulted in a significant increase (p < 0.05) in electrical conductivity (0.23 mS cm⁻¹) compared with the control. Soil organic matter and available phosphorus reached their highest values under B70F140, at 5.25% and 13.87 mg kg⁻¹, respectively, and were significantly greater than those in the control treatment. Soil available iron (Fe) and manganese (Mn) concentrations also increased significantly (p < 0.05) compared with the control, with the B35F70 and B70F70 treatments resulting in the highest Fe (371.29 mg kg⁻¹) and Mn (37.77 mg kg⁻¹) concentrations, respectively. At 100 days after amendment of the reddish-brown acidic soil, exploratory Pearson correlation analyses were conducted to examine relationships between soil health indicators and soybean performance. Soil available phosphorus and potassium exhibited positive associations with soil pH (r = 0.69 and r = 0.65, respectively; p < 0.01). Soybean growth traits, including plant height and number of leaves, were positively associated with seed yield (r = 0.56 and r = 0.77, respectively; p < 0.01). Furthermore, seed yield was positively correlated with SPAD values (r = 0.80, p < 0.01), soil pH (r = 0.56, p < 0.01), available K (r = 0.68, p < 0.01), and Mg (r = 0.47, p < 0.05). Principal component analysis (PCA) further demonstrated clear treatment clustering and consistent positive relationships among soil properties, plant growth traits, and soybean yield variables. The control treatment was clearly separated from all biochar-organic fertilizer treatments along PC1. Among all treatments, B35F140 (3.33 g biochar kg⁻¹ soil + 13.33 g organic fertilizer kg⁻¹ soil) showed the strongest positive association with soil health and plant growth and produced the highest soybean seed yield (10.77 g plant⁻¹). Overall, the combined use of biochar and organic fertilizer improved soil health, soybean growth, and yield, demonstrating its potential as a sustainable strategy for enhancing soybean productivity under acidic soil conditions.

Mycorrhizae are symbiotic associations between the roots of vascular plants and fungi that facilitate the uptake of water and nutrients by host plants. However, current arbuscular mycorrhizal fungi (AMF) cultivation methods including sand culture, root organ culture, and aeroponics are complex and time-consuming. Moreover, these methods produce low spore yields hindering large-scale production and sustainable application of MF in agriculture. This study systematically evaluated the effects of biochar amendment on the propagation of AMF spores in sandy soils, focusing on how different biochar application rates influence AMF spore density and related soil physicochemical properties. The results showed that increasing biochar concentration led to higher soil pH and EC, suggesting enhanced microbial activity and dynamic adjustments in soil chemical conditions. A typical biphasic response was observed. At low biochar concentrations (approximately 1–1.8%), soil porosity, organic carbon content, and trace element availability were improved, thereby promoting AMF spore formation and hyphal growth. However, concentrations exceeding 2.5% induced physicochemical stress that inhibited fungal propagation. Polynomial regression analysis (R² = 0.996) confirmed a strong correlation between biochar concentration and AMF spore density, clearly capturing a promotion–plateau–inhibition pattern. In addition, SEM imaging revealed that AMF hyphae adhered to the porous surface of biochar, forming stable hyphal networks that enhance nutrient transport and contribute to rhizosphere microenvironmental stability.