Search Results (197)

In a greenhouse experiment, we examined the behavior of biochar in arable soil to demonstrate that these supplements can boost soil carbon storage, as well as to track changes in microbial biomass and identify the microbial communities that use these biochars. In order to ascertain if biochar can consistently alter soil microbial activities, we studied the impact of biochar combination treatments on 16S rRNA gene diversity. In soil treated with biochar, there was a rise in the relative abundance of taxa belonging to the phyla Actinobacteria and Gemmatimonadetes, despite the overall diversity decreasing with biochar addition. According to all of these observations, pyrogenic carbon has a major effect on the composition of the soil microbial community and enriches keystone taxa within the parent soil microbial community. Certain species experienced increases throughout the biochar-amended incubation period, despite the total diversity declining following biochar amendments. The phyla Actinobacteria and Gemmatimonadetes increased in the relative abundance of bacteria in soil treated with biochar, according to DNA sequencing of these species. In summary, these findings show that biochar significantly impacts the constitution and composition of the soil microbial community and enriches important taxa within the parent soil microbial community. Full article

As a carbon-rich material with sufficient inorganic nutrients, biochar is potentially an inexpensive and suitable additive to improve the quality of soil and achieve sustainable agriculture. However, the addition of biochar generally increases pesticide adsorption in soil because of the well-maintained porous structure, and the specific effects of the properties of biochar, soil, and pesticides on the adsorption capacity of pesticides remain unknown. In this study, a meta-analysis was conducted to investigate the effects of biochar addition on pesticide adsorption in soils, focusing on characteristics such as the biochar addition dosage, biochar properties (pH, specific surface area (SSA), pore diameter, (O+N)/C, H/C), and soil properties (texture, initial pH, cation exchange capacity). Overall, wood-derived biochar that was treated at ≥700 °C for 2–4 h, with a pH of 9–10 and a 2–4% addition rate led to the greatest enhancement in the pesticide adsorption capacity of soil. Additionally, the pyrolysis temperature of the biochar, the biochar’s pore diameter, and the soil’s pH significantly influenced the adsorption capacity. Based on this meta-analysis, we conclude that the (O+N)/C ratio of biochar is the most influential predictor of soil’s pesticide adsorption capacity. Full article

Biochar has emerged as a promising soil amendment for mitigating heavy metal contamination in agricultural systems. This study investigates the effects of biochar on cadmium (Cd) and copper (Cu) uptake, plant growth, oxidative stress, and physiological responses in lettuce (Lactuca sativa L.) plants exposed to different metal concentrations. Results indicate that biochar significantly influenced Cd bioavailability, reducing its accumulation in plant tissues by up to 31.9% and alleviating oxidative stress, with malondialdehyde and proline levels decreasing by up to 51.0% and 60.2%, particularly at higher application rates (5%). Cd-exposed plants treated with biochar exhibited an improved fresh weight (+22.6%), lower malondialdehyde and proline levels, and enhanced the chlorophyll content (+14.9% to 24.1%) compared to untreated plants. The bioaccumulation factor for Cd decreased (up to 31.8%) while the immobilization index (II) increased, confirming the role of biochar in limiting Cd mobility in soil. In contrast, Cu uptake remained consistently low across all treatments, with a significant reduction observed only at higher contamination levels (up to −34.2%). Biochar contributed to Cu immobilization, reflected in increased II values, and enhanced the plant biomass and chlorophyll content under Cu exposure (+15.4% and up to +24.1%, respectively), suggesting a partial alleviation of Cu toxicity. These findings highlight biochar’s potential in heavy metal remediation, particularly for Cd, by reducing bioavailability and improving plant resilience. However, its role in Cu-contaminated soils is mainly through immobilization rather than uptake reduction. Full article

The amount of waste generated by society is constantly increasing. Consequently, there is a need to develop new and better methods of treating it. A significant part of municipal waste is biowaste, which can be treated as a source of valuable resources such as nutrients, organic matter, and energy. The present work aims to determine the properties of the tested household biowaste and the possibility of using it as feedstock in slow pyrolysis to obtain biochar. The slow pyrolysis process of the biowaste was carried out in an electrically heated Horizontal Tube Furnace (HTF) at temperatures of 400 °C, 500 °C, and 600 °C in a nitrogen atmosphere. The analysis showed that depending on the type and composition of the biowaste, its properties are different. All the biowaste tested has a high moisture content (between 63.51% and 81.53%), which means that the biowaste needs to be dried before the slow pyrolysis process. The characteristics of kitchen biowaste are similar to those of food waste studied by other researchers in different regions of the world. In addition, the properties of kitchen biowaste are similar to those of the typical biomasses used to produce biochar via slow pyrolysis, such as wood, almond shells, and rice husks. Both kinds of garden biowaste tested may have been contaminated (soil, rocks) during collection, which affected the high ash content of spring (17.75%) and autumn (43.83%) biowaste. This, in turn, affected all the properties of the garden biowaste, which differed significantly from both the literature data of other garden wastes and from the properties of typical biomass feedstocks used to produce biochar in slow pyrolysis. For all biowaste tested, it was shown that as the pyrolysis temperature increases, the yield of biochar decreases. The maximum mass yield of biochar for kitchen, spring garden, and autumn garden biowaste was 36.64%, 66.53%, and 66.99%, respectively. Comparing the characteristics of biowaste before slow pyrolysis, biochar obtained from kitchen biowaste had a high carbon content, fixed carbon, and a higher HHV. In contrast, biochar obtained from garden biowaste had a lower carbon content and a lower HHV. Full article

The application of animal manure and organic soil amendments as an alternative to expensive inorganic fertilizers is becoming more prevalent in the USA and worldwide. A field experiment was conducted on Bluegrass–Maury silty loam soil at the Kentucky State University Research Farm using the Kennebec variety of white potato (Solanum tuberosum) under Kentucky climatic conditions. The study involved 12 soil treatments in a randomized complete block design. The treatments included four types of animal manures (cow manure, chicken manure, vermicompost, and sewage sludge), biochar at three application rates (5%, 10%, and 20%), and native soil as control plots. Additionally, animal manures were supplemented with 10% biochar to assess the influence of combining biochar with animal manure on the accumulation of heavy metals in potato tubers. The study aimed to (1) determine the concentration of seven heavy metals (Cd, Cr, Ni, Pb, Mn, Zn, Cu) and two essential nutrients (K and Mg) in soils treated with biochar and animal manure, and (2) assess metal mobility from soil to potato tubers at harvest by determining the bioaccumulation factor (BAF). The results revealed that Cd, Pb, Ni, Cr, and Mn concentrations in potato tubers exceeded the FAO/WHO allowable limits. Whereas the BAF values varied among the soil treatments, with Cd, Cu, and Zn having high BAF values (>1), and Pb, Ni, Cr, and Mn having low BAF values (<1). This observation demonstrates that potato tubers can remediate Cd, Cu, and Zn when grown under the soil amended with biochar and animal manure. Full article

Soil degradation and water scarcity pose major challenges to sustainable agriculture in semiarid regions, requiring innovative strategies to enhance water use efficiency (WUE) and soil fertility. This study assessed the effects of sewage sludge biochar (SSB) on soil properties, WUE, and common bean yield through a small-scale controlled field experiment under rainfed conditions in Northeast Brazil. Four SSB application rates (5, 10, 20, and 40 t ha⁻¹) were compared with conventional NPK fertilization, treated sewage sludge (SS), and chicken manure (CM). The application of 20 t ha⁻¹ (B20) significantly improved soil organic carbon, nitrogen content, water retention, and microbial biomass. B20 also increased WUE by 148% and grain yield by 146% relative to NPK, while maintaining safe levels of potentially toxic elements (PTE) in bean grains. Although 40 t ha⁻¹ (B40) enhanced soil fertility further, it posed a risk of PTE accumulation, reinforcing the advantage of B20 as an optimal and safe dose. These results highlight the potential of SSB to replace or complement conventional fertilizers, especially in sandy soils with limited water retention. The study supports SSB application as a sustainable soil management practice that aligns with circular economy principles, offering a viable solution for improving productivity and environmental resilience in semiarid agriculture. Full article

Heavy metal (HM) contamination poses a major threat to environmental health, agriculture and human well-being, requiring effective and sustainable remediation strategies. Phytoremediation, an eco-friendly and cost-effective approach, is widely used for the remediation of HM-contaminated soils. Although phytoremediation holds considerable potential in the extraction, stabilisation and degradation of HMs, its effectiveness is often constrained by limited metal bioavailability, plant stress under toxic conditions and slow metal uptake rates. To address these limitations, this review examines the integration of various soil amendments—the application of biochar, compost, plant exudates, microbial agents and chelating agents—to enhance phytoremediation efficiency. This review critically evaluates empirical evidence on the effectiveness, scalability, economic feasibility and environmental impact of these amendments. By synthesising recent studies, this review advances the understanding of amendment-assisted phytoremediation as a viable solution for treating HM-contaminated soils. In addition, this review identifies practical applications, discusses limitations and explores the potential synergies of these amendments to optimise phytoremediation strategies, ultimately contributing to more effective and sustainable environmental cleanup efforts. Full article

Soil salinization presents a significant challenge, driven by factors such as inadequate drainage, shallow aquifers, and high evaporation rates, threatening global food security. The sunflower emerges as a key cash crop in such areas, providing the opportunity to convert its straw into biochar, which offers additional agronomic and environmental benefits. This study investigates the effectiveness of biochar interlayers in enhancing salt leaching and suppressing upward salt migration through integrated laboratory and field experiments. The effectiveness of varying biochar interlayer application rates was assessed in promoting salt leaching, decreasing soil electrical conductivity (EC), and enhancing crop performance in saline soils through a systematic approach that combines laboratory and field experiments. The biochar treatments included a control (CK) and different applications of 20 (BL20), 40 (BL40), 60 (BL60), and 80 (BL80) tons of biochar per hectare, all applied below a depth of 20 cm, with each treatment replicated three times. The laboratory and field experimental setups maintained consistency in terms of biochar treatments and interlayer placement methodology. During the laboratory column experiments, the soil columns were treated with deionized water, and their leachates were analyzed for EC and major ionic components. The results showed that columns with biochar interlayers exhibited significantly higher efflux rates compared to those of the control and notably accelerated the time required for the effluent EC to decrease to 2 dS m⁻¹. The CK required 43 days for full discharge and 38 days for EC stabilization below 2 dS m⁻¹. In contrast, biochar treatments notably reduced these times, with BL80 achieving discharge in just 7 days and EC stabilization in 10 days. Elution events occurred 20–36 days earlier in the biochar-treated columns, confirming biochar’s effectiveness in enhancing leaching efficiency in saline soils. The field experiment results supported the laboratory findings, indicating that increased biochar application rates significantly reduced soil EC and ion concentrations at depths of 0–20 cm and 20–40 cm, lowering the EC from 7.12 to 2.25 dS m⁻¹ and from 6.30 to 2.41 dS m⁻¹ in their respective layers. The application of biochar interlayers resulted in significant reductions in Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl⁻, SO₄²⁻, and HCO₃⁻ concentrations across both soil layers. In the 0–20 cm layer, Na⁺ decreased from 3.44 to 2.75 mg·g⁻¹, K⁺ from 0.24 to 0.11 mg·g⁻¹, Ca²⁺ from 0.35 to 0.20 mg·g⁻¹, Mg²⁺ from 0.31 to 0.24 mg·g⁻¹, Cl⁻ from 1.22 to 0.88 mg·g⁻¹, SO₄²⁻ from 1.91 to 1.30 mg·g⁻¹ and HCO₃⁻ from 0.39 to 0.18 mg·g⁻¹, respectively. Similarly, in the 20–40 cm layer, Na⁺ declined from 3.62 to 3.05 mg·g⁻¹, K⁺ from 0.28 to 0.12 mg·g⁻¹, Ca²⁺ from 0.39 to 0.26 mg·g⁻¹, Mg²⁺ from 0.36 to 0.27 mg·g⁻¹, Cl⁻ from 1.18 to 0.80 mg·g⁻¹, SO₄²⁻ from 1.95 to 1.33 mg·g⁻¹ and HCO₃⁻ from 0.42 to 0.21 mg·g⁻¹ under increasing biochar rates. Moreover, the use of biochar interlayers significantly improved the physiological traits of sunflowers, including their photosynthesis rates, stomatal conductance, and transpiration efficiency, thereby boosting biomass and achene yield. These results highlight the potential of biochar interlayers as a sustainable strategy for soil desalination, water conservation, and enhanced crop productivity. This approach is especially promising for managing salt-affected soils in regions like California, where soil salinization represents a considerable threat to agricultural sustainability. Full article

Mercury (Hg) contamination in soils poses significant environmental risks. In response, various nature-based solutions (NbSs) have been developed and studied in the past to treat mercury along with other heavy metals from both point and nonpoint sources. However, various land uses present uncertainties in mercury mobility and treatment efficiency, affecting the scalability of NbS systems. In this study, a systematic review of peer-reviewed articles addressing mercury pollution in NbS soils was conducted. Results revealed that lakeside environments and mining areas are key Hg accumulation zones due to hydrological connectivity and anthropogenic pressures. Constructed wetlands were the most studied NbSs, where those with Acorus calamus and Aquarius palifolius as the main vegetation achieved >90% Hg removal efficiencies. Although NbSs achieved high Hg removal, anaerobic conditions were found to promote MeHg formation, a critical drawback. Moreover, biochar demonstrated potential for immobilizing Hg and reducing bioavailability, though certain types increased MeHg formation under specific redox conditions. Overall, the study highlighted the need for site-specific design, long-term field evaluation, and multidisciplinary strategies to optimize NbS performance for mercury removal. Furthermore, future research on the scalability of mercury-treating NbSs across diverse land uses is recommended to address mercury risks and improve effectiveness. Full article

Biochar may represent a sustainable and eco-friendly strategy to recycle agroforestry wastes, sequester carbon and improve soil health. With the aim of proving these benefits in a real scenario, we treated several soil parcels with 0 (CTRL), 1 (LOW) and 3 (HIGH) kg/m² of wood biochar, in open-field trials. The heterotrophic soil respiration (SR) was monitored continuously for two months via a Closed Dynamic Chamber (CDC) associated with an innovative pilot system, and the most important soil chemical parameters were measured 9 and 54 days after biochar application. Biochar induced an immediate dose-dependent increase in organic matter content and CEC (up to 41.6% and 36.8% more than CTRL, respectively), which tended to slightly and gradually decrease after 54 days. In all cases, biochar induced a more pronounced SR, although the most enhanced microbial response was detected for the LOW parcel (19.3% higher than CTRL). Fennels were grown in treated soils and only LOW microplots gave a significantly better response (weight and size). Finally, NMR, FT-IR and Pyr-GC/MS analyses of LOW SOM extracts revealed a relevant impact on the composition, which was accompanied by a higher content of carbohydrates, indole-based compounds and FAME species correlating with enhanced microbial activity. Our findings demonstrate that the proper biochar dose improves soil fertility by creating an environment favorable to plants and promoting microbial activity. Full article

The effective management of produced water (PW), a by-product of oil extraction in Oman, is essential for sustainable water use and environmental protection. PW contains petroleum residues, heavy metals, and salts, which require treatment before safe reuse. In the Nimr oil field, PW undergoes partial treatment in constructed wetlands vegetated with buffelgrass (Cenchrus ciliaris). This study investigated the reuse potential of treated PW for irrigation through two parallel field experiments conducted at Sultan Qaboos University (SQU) and the Nimr wetlands site. At the SQU site, native halophytic plants were irrigated with three water sources: treated municipal wastewater, underground water (from an on-site well), and treated produced water. At the Nimr site, irrigation was conducted using underground water and treated PW. Two soil types were used: well-draining control soil and Nimr soil from southern Oman. The treatments included: (i) PW + control soil, (ii) PW + Nimr soil, (iii) PW + gypsum (3.5 g/kg soil), (iv) PW + biochar (10 g/kg soil), (v) underground water + control soil, and (vi) treated municipal wastewater + control soil. Biochar, produced from locally sourced buffelgrass via low-temperature pyrolysis (300 °C for 3 h), and gypsum (46.57% acid-extractable sulfate) were mixed into the soil before sowing. The impact of each treatment was assessed in terms of soil quality (salinity, boron, major cations), plant physiological responses, and mineral accumulation. PW irrigation (TDS ~ 6500–7000 mg/L) led to a sixfold increase in soil sodium and raised boron levels in plant tissues to over 200 mg/kg, exceeding livestock feed safety limits. Copper remained within acceptable thresholds (≤9.5 mg/kg). Biochar reduced boron uptake, but gypsum showed limited benefit. Neither amendment improved plant growth under PW irrigation. These findings highlight the need for regulated PW reuse, emphasizing the importance of soil management strategies and alternating water sources to mitigate salinity stress. Full article

Aiming at the remediation of soil in mining areas caused by mining activities, pot experiments were conducted using water jet-loom sludge (WJLS) and biochar as soil amendments to evaluate their potential for enhancing soil fertility and microbial communities of degraded mining soils. Six treatments with varying WJLS (0%, 5%, 15%) and biochar (0%, 3%) application rates were evaluated. Results showed that WJLS can significantly improve soil organic carbon (OC), total nitrogen (TN), total phosphorus (TP), and microbial biomass, while reducing soil pH and enhancing ryegrass biomass by 1.6–4.1 times. However, a 3% biochar addition may increase the soil sodium absorption ratio (SAR). Moreover, the role of biochar was mainly reflected in the microbiological properties. The combining of WJLS and biochar increased the soil microbial biomass and obviously improved the diversity and abundance of bacteria and fungi in the soil (p < 0.05) after the amendment, especially in the biochar addition groups. At the phylum level, the relative abundance of Proteobacteria, Firmicutes, and Actinobacteriota accounted for 72.4%~84.2% of soil bacteria in all treatments, while the fungi were dominated by Ascomycota (58.30%~95.36%) and Fungi_unclassified (1.26%~38.97%), all of which were significantly related to enhanced soil properties especially OC, TN, TP, and cation exchange capacity (CEC). Overall, WJLS and biochar demonstrate strong potential as sustainable amendments for improving soil fertility and biological quality in the reclamation of mining-affected lands. Full article

Tomato is a major crop, and efforts are ongoing to enhance its resilience to biotic and abiotic stresses. Weed management remains a key challenge, prompting the search for sustainable alternatives to reduce the impact of excessive herbicide use. Biochar is a promising alternative, as it enriches the soil, improves its water retention capacity, promotes its regeneration and increased fertility, delays nutrient leaching, and improves fertilizer use efficiency. This study aimed to investigate the efficiency of biochar use in mitigating stress caused by different herbicides. Two different biochar materials, Douglas fir and rice husk, were used. Tomato seeds were sown in pots and arranged in a randomized design. At the 4V stage (28 days after sowing), the herbicides S-metolachlor, metribuzin, and halosulfuron were applied. Plant length, injury, antioxidant enzyme activity, ascorbate peroxidase (APX), catalase (CAT), guaiacol peroxidase (GPOD), glutathione reductase (GR), and hydrogen peroxide content (H₂O₂) were assessed 7 and 14 days after herbicide application. Plants treated with biochar and submitted to herbicide treatments showed significantly higher growth parameters and fewer injuries when compared to plants treated with herbicides without biochar. The antioxidant response of the plants followed the same trend; smaller plants with more injuries showed greater H₂O₂ accumulation and significantly higher antioxidant enzyme activity. These findings highlight the protective effect of biochar, particularly Douglas fir biochar, as it effectively mitigated herbicide-induced oxidative stress and helped maintain plant growth and structural integrity under treatment conditions. Full article

Tropical acidic soils exhibit inherently low fertility and reduced microbial activity, driven by low pH and accelerated organic matter mineralization, phosphorus (P) fixation, and aluminum (Al³⁺) and iron (Fe³⁺) toxicity. These constraints limit agricultural productivity, necessitating sustainable and low-cost soil amendments essential for improving the soil fertility in such regions. This study investigated the effects of biochar, kitchen stove ash (KSA), and their combined application on the soil chemical properties, nutrient dynamics, and microbial functions in a tropical acidic soil. The treatment included the unamended control and two doses of 0.25% w/w (B₁₀) and 0.5% w/w (B₂₀) corncob biochar, 0.03% w/w kitchen stove ash (A_sh), and 0.027% w/w commercial-grade calcium carbonate (L_ime). Each biochar dose was added alone or in combination with either ash (A_sh + B₁₀ and A_sh + B₂₀) or calcium carbonate (L_ime + B₁₀ and L_ime + B₂₀). After eight weeks of laboratory incubation at 20 °C, the soil pH, N and P bioavailability, microbial biomass, and extracellular enzyme activities were measured. The combined application of 0.5% w/w biochar with 0.03% w/w KSA (A_sh + B₂₀) resulted in the most significant improvements in all of the examined soil fertility indicators than the individual amendments. Specifically, the soil pH was increased by 40% (+1.9 pH units) compared with the unamended control. Available phosphorus, mineral nitrogen, and total potassium were increased by 49%, 22%, and 36%, respectively, compared with the unamended control. Regarding the microbial parameters, the A_sh + B₂₀-treated soil showed the highest microbial respiration (+56%), microbial biomass (+45%), and extracellular C- and N-cycling enzyme activities compared with the unamended soil. The ash supplied minerals (P, K, and Mg) provided a more beneficial effect on the soil’s nutrient content and microbial functions than the calcium carbonate. The study demonstrated that underutilized kitchen ash may supplement biochar’s liming and nutrient supply potentials, even at a lower application rate, to improve the fertility of weathered acidic soil. Full article

The accumulation of heavy metal cadmium (Cd) in farmland soil in edible parts of crops seriously threatens plant growth, human health, and even the global ecological environment. Finding stabilization remediation technology is an important means to treat Cd-contaminated soil. This study comprehensively evaluated the synergistic effects of independent or combined application of biochar (BC) (10, 30 g kg⁻¹) and nano zero-valent iron (nZVI) (0.1% w/w) on soil properties and morphological and physiological traits of pakchoi (Brassica rapa L. subsp. chinensis) under Cd (1, 3 mg kg⁻¹) stress by pot experiments. It was shown that Cd toxicity negatively affected soil properties, reduced pakchoi biomass and total chlorophyll content, and increased oxidative stress levels. On the contrary, the combined application of BC (30 g kg⁻¹) and nZVI (0.1%, w/w) reduced the Cd accumulation in the shoot parts of pakchoi from 0.78 mg·kg⁻¹ to 0.11 mg·kg⁻¹, which was lower than the Cd limit standard of leafy vegetables (0.20 mg kg⁻¹) in GB 2762-2017 “National Food Safety Standard”. Compared with the control, the treatment group achieved a 61.66% increase in biomass and a 105.56% increase in total chlorophyll content. At the same time, the activities of catalase (CAT) and superoxide dismutase (SOD) increased by 34.86% and 44.57%, respectively, and the content of malondialdehyde (MDA) decreased by 71.27%. In addition, the application of BC alone (30 g·kg⁻¹) increased the soil pH value by 0.43 units and the organic carbon (SOC) content by 37.82%. Overall, the synergistic effect of BC (30 g kg⁻¹) and nZVI (0.1% w/w) helped to restore soil homeostasis and inhibit the biotoxicity of Cd, which provided a new option for soil heavy metal remediation and crop toxicity mitigation. Full article