Search Results (624)

This study investigated the mechanism underlying how the integration of chemical fertilizer and maize straw-derived organic amendments affects different potassium (K) pools, K saturation, K fixation characteristics, and non-exchangeable potassium (NEK) release kinetics in black soil. A field experiment involving five treatments was conducted: no fertilizer (CK), chemical fertilizer alone (NPK), chemical fertilizer plus maize straw (NPK+ST), chemical fertilizer plus straw compost (NPK+CP), and chemical fertilizer plus straw biochar (NPK+BR). The findings demonstrated remarkably increased contents of different K pools and K saturation in the black soil following the combined application of straw-derived organic amendments, with NPK+CP exhibiting the most significant effect. Exogenous K fixation simulation tests indicated that the amount of K fixation in the black soil increased with the incorporation of exogenous K, while the fixation rate showed the opposite trend. The quadratic regression model well fitted the relationship between the amount of K fixation and the addition of exogenous K; the treatments were ranked according to the soil K fixation capacity as follows: CK > NPK > NPK+BR > NPK+ST > NPK+CP. The simplified Elovich model well fitted the NEK release process in the black soil under different treatments. Significant differences in total cumulative NEK release and apparent release rate coefficients were observed among the treatments, which showed an identical trend: NPK+CP > NPK+BR > NPK+ST > NPK > CK. The application of straw-derived organic amendments could effectively reduce the K fixation capacity of black soil and promote NEK release. In this study, chemical fertilizer combined with straw compost was the optimal measure for improving black soil’s potassium availability. Full article

Environmental concerns with petroleum-based polymers have accelerated the development of biodegradable alternatives, making poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) a promising candidate for sustainable packaging. However, its functional performance necessitates modification through blending. In this study, blends containing 65–85 wt.% polylactide (PLA) were investigated to establish structure–property relationships relevant to compostable packaging. The results reveal partial miscibility of the blends and pronouncedcomposition-dependent changes in morphology and thermal behavior, characterized by an increase in glass transition temperature and a decrease in PLA melting temperature. Increasing PLA content (≥80 wt.%) enhanced thermal stability, increasing the degradation temperature to 288.0 °C. In contrast, higher PHBV content (≥25 wt.%) significantly improved barrier properties of PLA, reducing oxygen and water vapor transmission rates to 74.47 cm³ m⁻² day⁻¹ and 29.11 g m⁻² day⁻¹, respectively. Biodegradation behavior revealed complete degradation of PHBV after 56 days, whereas PLA showed only 1.29% mass loss under identical conditions. In the blends, biodegradation proceeded preferentially through the PHBV phase, resulting in composition-dependent mass loss. Among the investigated compositions, PLA65/PHBV provided the most balanced combination of barrier performance, mechanical behavior, and biodegradation response. Overall, these findings demonstrate that tailoring composition enables the design of polymer systems for sustainable packaging applications. Full article

In arid and semi-arid regions, severe salinity imposes strong abiotic constraints on farmland restoration. This study evaluated the one-season effects of organic amendments on soil quality, maize productivity, and short-term ecosystem multifunctionality (EMF) responses under severe salinity stress. We conducted a field experiment with biofertilizer (targeting plant–soil biological regulation) and composted manure (targeting direct soil amelioration) applied at different rates. The high-rate composted manure treatment (T6) showed the largest short-term improvements: compared with the chemical-fertilizer-only control under the same irrigation and plastic-mulch management (CK; soil quality index (SQI) = 0.716, yield = 6.657 t ha⁻¹, EMF_a = 0.456), SQI increased by 165%, maize yield increased by 41%, and EMF_a increased by 104% relative to CK within one growing season. Partial least squares path modeling (PLS-PM) suggested that under biofertilizer treatments, a plant-related association pathway was observed but relatively weak (β = 0.215), whereas under composted manure treatments, EMF variation was mainly associated with soil quality improvement (β = 0.992). Overall, these short-term results suggest that, under the tested application rates and severe salinity stress, high-rate composted manure can more effectively improve baseline soil conditions than biofertilizers during the initial season. These findings offer a preliminary conceptual perspective for a phased management strategy, serving strictly as a preliminary hypothesis where priority is given to soil amelioration in the initial phase and gradual integration of biologically oriented interventions as baseline conditions improve. However, future multi-year and multi-site studies are strictly required to validate the long-term viability of this proposed framework and to test whether these association patterns persist across longer time scales and broader regional contexts. Full article

Compost offers high potential for sustainable agriculture, but its agronomic outcomes vary. This critical review combines qualitative evidence with literature-derived quantitative benchmarks for compost maturity, salinity, nutrient loading, application-rate classes and monitoring triggers. Evidence demonstrates that mature, stable composts consistently improve soil health, including aggregation, water-holding capacity, soil organic carbon (SOC), and nutrient availability while boosting crop yield and establishment. These high-quality composts are characterized by low phytotoxicity, moderate C:N ratios, acceptable EC levels, and pathogen compliance. However, benefits are not universal. Immature or poorly stabilized compost poses risks of phytotoxicity, ammonia toxicity, and nitrogen immobilization. Excessive application rates are associated with nutrient imbalances, increased salinity, nitrate leaching, phosphorus runoff, greenhouse-gas trade-offs, and cumulative contaminant loading. To enhance the precision of rate recommendations, this review categorizes applications into four distinct tiers: starter or maintenance (2–5 Mg dry matter ha⁻¹), common agronomic (5–20 Mg ha⁻¹), rehabilitation (20–35 Mg ha⁻¹), and high-risk (>35 Mg ha⁻¹). It posits that the final application rate must be dictated by the most limiting factors, such as crop nitrogen requirements, soil-test phosphorus levels, salinity tolerance, contaminant thresholds, hydrologic risk, or specific management objectives. In conclusion, while manure-based composts enhance short-term fertility, they introduce significant risks of phosphorus accumulation and salinity compared to green-waste alternatives. This review, therefore, redefines compost not as a generic organic amendment, but as a quality-controlled, rate-sensitive input essential for precision nutrient management. Full article

Aquaculture solid waste (ASW) from intensive farming poses significant environmental challenges, yet its potential as a composting feedstock remains insufficiently evaluated. This study systematically assessed the feasibility of aerobic composting for ASW valorization through integrated feedstock characterization, composting process monitoring, microbial community analysis, and pot experiment validation. ASW collected from intensive aquaculture facilities was characterized by high phosphorus (mean TP: 6.80 mg/g), potassium (TK generally >10 mg/g), and iron (mean Fe: 49,112 mg/kg) content but low organic matter (17.60%) and total nitrogen (0.72%). Composted with rice straw powder, meat and bone meal, and mineral amendments, ASW was successfully converted into mature compost, with the thermophilic phase (>50 °C) lasting only 4 days and the seed germination index exceeding the 80% safety threshold within 15 days. The composting process exhibited an organic matter degradation rate of approximately 20.82%, along with low electrical conductivity and stable pH in the final product. Microbial community analysis revealed that ASW addition significantly altered bacterial and fungal community structure, enriching functional taxa associated with organic matter decomposition and nutrient transformation. Pot experiments conducted under equal nutrient input conditions demonstrated that the ASW-derived compost supported satisfactory crop growth, with the fresh weight of Fast-growing Cabbage reaching 106.95 g per plant. The compost also improved soil properties, including reduced electrical conductivity (72.8% lower than urea), increased soil organic matter (17.8% increase over original soil), and enhanced available phosphorus (93.0% increase over original soil). These results indicate that aerobic composting is a technically viable pathway for converting ASW into a qualified organic fertilizer, providing a preliminary scientific basis for future waste management strategy for the sustainable development of the aquaculture industry. Full article

Sustainable phosphorus (P) management in agriculture requires a circular economy approach through the use of so-called bio-based fertilizers (BBFs). The properties of BBFs vary widely depending on raw materials and production processes. However, it is still unknown how these properties, and particularly the dominant P compounds determine not only the efficiency of BBFs in supplying P to crops, but also their effects on soil functioning and crop quality. This study aimed to evaluate the efficiency of a representative set of BBFs, and relate this efficiency to their composition and dominant P compounds. To this end, 14 BBFs were studied: four from water purification (struvite, vivianite, and sewage sludge with and without composting), four composts (municipal solid waste (MSW), vineyard residues, and two using olive husks), three vermicomposts (two homemade and one commercial), fish meal, digestate, and a commercial organic fertilizer. Phosphorus forms in BBFs were determined using ³¹P nuclear magnetic resonance spectroscopy (P-NMR). The BBFs were compared to a single superphosphate (SSP) in a pot experiment growing wheat in two different alkaline soils, one rich in iron (Fe) oxides and one rich in carbonates. The effects on critical elements in grain [magnesium, Fe, zinc (Zn), manganese, and copper] and enzyme activities related to soil functioning and P cycling were also assessed. The dominant P compound in the BBFs was orthophosphate (73.8–89.5% of the total P in the NaOH–EDTA extracts). The MSW had the highest polyphosphate content (4.1%), a complex inorganic P compound. The organic P content ranged from 9.2% (fish meal) to 25.5% (Moge). Sewage sludge and composted sludge contributed high levels of phosphonates (4.1 and 5.6% of extracted P). The most abundant organic P compound class was inositol hexakisphosphates (IHPs), and myo-IHP (phytate) was the dominant IHP stereoisomer (1.2–6.4%) followed by D-chiro-IHP and scyllo-IHP. Plant dry matter and grain yield with most BBFs were not significantly different from that of SSP in both soils, likely due to the high concentrations of phosphate in relatively soluble forms in most of the BBFs. Vivianite and sewage sludge resulted in significantly higher grain yield than SSP (43% and 40%, respectively) in the carbonate-rich soil, likely due to progressive phosphate dissolution, which decreased the precipitation rate of insoluble calcium (Ca) phosphates. The highest P recoveries were obtained with horse manure vermicompost (65% and 15% higher than SSP in the Fe oxide-rich and in the carbonate-rich soil, respectively), partially attributed to the decreased precipitation rate of insoluble Ca phosphates with the added organic matter. Some BBFs increased micronutrient concentrations in grains and most decreased the P-to-Zn ratio relative to SSP. Overall, phosphatase and β-glucosidase activities increased with carbon-rich BBFs. Most of the studied BBFs could effectively replace fertilizers from non-renewable sources, in some cases with better crop P recoveries. Furthermore, some BBFs could provide additional benefits to grain quality, in terms of micronutrient supply for humans, and soil functioning. Full article

Thermophilic microbial inoculant (CI) has been demonstrated to optimize the green waste composting (GWC) process. The pathways through which it enhances lignocellulose degradation remain unclear. This study evaluated composting performance under four treatments: CI, effective microorganisms (EM), Phanerochaete chrysosporium (WF), and natural composting (CK). To elucidate the biological differences between efficient lignocellulose-degrading systems and CK, metagenomic analyses were conducted on CI and CK based on lignocellulose degradation rates. The results indicated that CI inoculation did not negatively affect the compost heating process and produced a nitrogen-rich, safe, and mature compost product. Compared to other treatments, CI increased the lignocellulose degradation rate by 3.66% to 31.8%. Metagenomic analysis revealed that CI inoculation enriched genes encoding glycoside hydrolases (GHs), glycosyl transferases (GTs), carbohydrate esterases (CEs), and carbohydrate-binding modules (CBMs) across multiple composting phases, positively impacting dominant carbohydrate-active enzyme (CAZyme) families including AA3, CE1, and CE7. CI inoculation also elevated the relative abundance of lignocellulose-degrading microorganisms (0.70~2.73%), simplified microbial network structure, and strengthened microbial cooperation. Within the microbial network, Chryseolinea, Protaetiibacter, and unclassified_f__Burkholderiaceae were identified as core taxa involved in lignocellulose degradation. Redundancy analysis (RDA) identified temperature as the primary factor influencing biological factors, with CI improving composting efficiency by optimizing the microenvironment. Collectively, this work provides a novel strategy for microbial inoculant application in composting and offers new perspectives for identifying core taxa, contributing to advancing composting efficiency. Full article

The deposition of volcanic ash in areas affected by erupting volcanoes can contaminate the soil with heavy metals, thereby jeopardizing food security and public health. This study focused on the use of compost for the bioremediation of this type of contaminated soil and on evaluating the effectiveness of this remediation technique in a horticultural crop. To this end, composts made from organic waste generated in the areas with volcanic-ash-affected soil, such as crop residues, cow manure, and cheese whey, were used. The design and optimization of the composting process for these wastes were described using three piles with the same proportion of crop residues and cow manure but different doses of whey (pile 1: without whey, pile 2: whey diluted with water (1:2 (v:v)); and pile 3: with undiluted whey) and by monitoring the evolution of physicochemical and biological parameters throughout the compositing process. The effectiveness of the composts obtained for soil remediation was evaluated by assessing the physiological response of a lettuce crop in pots. Five treatments were used: control soil without fertilization, inorganic fertilization, and the three composts obtained. The main agronomic properties of the soil and heavy metal availability were measured, along with the physiological and chemical parameters of the lettuce, including growth and macronutrient and heavy metal content. The results obtained in the composting experiment showed that the addition of cheese whey only affected the rate of organic matter degradation and the salt content of the final composts, without negatively affecting the stability and humification of their organic matter or their plant nutrient content. In the pot experiment, all composts improved soil fertility and reduced the availability of Ni, As, Cd, and Pb, but this did not consistently reduce uptake into lettuce, except in the case of Pb. Therefore, it is advisable to adjust the compost application rate and optimize crop selection to minimize the impact of heavy metals on the food chain, thereby ensuring safe production. Full article

Animal manure represents a critical reservoir that facilitates the dissemination of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs). However, the current understanding of ARG evolution during extensive composting remains insufficient. This study systematically investigated two common aerobic composting techniques: push-flow trough composting (FC) and membrane-covered composting (FM). Results indicated that both processes demonstrated substantial antibiotic removal capacities, achieving total removal rates of 88.89% (FC) and 79.20% (FM). Nevertheless, their effectiveness in removing ARGs varied considerably. During the 31 days of composting, the total removal rates of ARGs were 59.97% (FC) and 76.11% (FM), while the removal rates for class 1 integron (intI1) were 2.31% (FC) and 69.13% (FM). With the exception of tetX, tetG, and tetW, all other ARGs exhibited a rebound during the later stage of the FC process. In contrast, the FM process effectively reduced the risk of ARG rebound during this phase, which can be attributed to its extended thermophilic period and the physical barrier effect of the semi-permeable membrane. Network analysis indicated that ARGs were primarily associated with Bacillota and Pseudomonadota. The Partial Least Squares Path Model (PLS-PM) revealed that the bacterial community was the main factor influencing ARG dynamics in FC, while in FM, both the bacterial community and intI1 were the primary drivers. This study provides critical insights for optimizing composting strategies to prevent the dissemination of antibiotic resistance. Full article

Bioaerosol emissions from biological treatment processes like composting, livestock operations, and wastewater plants pose notable occupational and environmental health risks. Biofiltration is a common mitigation measure for gaseous pollutants, but its effectiveness in controlling bioaerosols is less studied. This review synthesizes current evidence on biofiltration for the removal of bioaerosols. Findings indicate that biofiltration can significantly reduce emissions from waste-related biological processes, although results vary widely and depend heavily on design and operational factors. In composting, agricultural, and wastewater treatment contexts, fungal bioaerosols are consistently removed with high efficiency, often over 90%. Conversely, bacterial removal shows greater variability, from negligible to above 90%, influenced primarily by airflow rate, bed depth, and media stability. Systems with residence times of tens of seconds and bed depths of at least 1 m tend to reliably reduce bacterial counts, whereas undersized, high-flow systems experience marked efficiency losses. The choice of packing material is also crucial; mature, stable media maintain performance, whereas nutrient-rich or unstable substrates can lead to fungal emissions, turning the biofilter into a secondary source. Data on endotoxin removal are limited and remain insufficient for firm design recommendations. Overall, biofiltration’s effectiveness depends on complex interactions among physical retention, biological stability, and design. These insights emphasize the need for future research to focus on standardized, performance-based design criteria supported by consistent reporting and full-scale validation. Full article

Strawberry cultivation generates substantial amounts of agricultural by-products, including spent substrates and plant residues, particularly in hydroponic production systems. However, information on the occurrence and management of these by-products remains limited. This study investigated the generation, disposal practices, and chemical characteristics of by-products from hydroponic strawberry cultivation in two major strawberry-producing regions of Republic of Korea, Nonsan and Jinju. Based on national statistics and field surveys, annual by-product generation was estimated at 605,400 m³ of spent substrates and approximately 25,729 t fresh weight and 6003 t dry weight of plant residues. Disposal practices varied regionally: in Jinju, over 80% of by-products were recycled as compost or feed, whereas in Nonsan, recycling rates were lower and a considerable portion remained untreated or were improperly disposed of. Analyses of 463 pesticides and seven heavy metals (Zn, Cu, Ni, Pb, As, Cd, and Hg) confirmed concentrations below the permissible limits, supporting their chemical suitability for potential recycling use. Inorganic analyses revealed high levels of N, Ca, P, and K, suggesting their potential as alternative nutrient sources and as raw materials for recycled fertilizer or soil amendment. Because strawberry by-products are generated continuously throughout the cultivation cycle, their management requires decentralized and long-term strategies. These results provide the first comprehensive assessment of the generation scale, disposal practices, and chemical characteristics of strawberry by-products in Republic of Korea, suggesting their potential as alternative nutrient resources or raw materials for recycled fertilizer or soil amendment under appropriate pretreatment and management. Full article

Inadequate Municipal Solid Waste (MSW) management constitutes a critical environmental challenge, as approximately 40% of waste reaches uncontrolled disposal sites where open-air incineration generates significant air, soil, and water pollution. The objective of this study was to evaluate the MSW Environmental Management System (EMS) in Chilpancingo de los Bravo, Guerrero, Mexico, through sustainability indicators and applicable Mexican environmental regulations to identify operational and structural deficiencies that guide a comprehensive improvement in its management. The methodology comprised an analysis of the EMS via the Municipal Development Plan, the identification of environmental indicators and applicable Mexican standards, and an evaluation of the EMS through waste characterization and sustainability metrics. A sample of 208 kg was defined in accordance with standards NMX-AA-015-1985 and NMX-AA-022-1985. The results indicate a generation rate of approximately 350 tons per day (1.2 kg/capita/day), with municipal collection coverage of 70% of the territory across 24 daily routes operated by 30 vehicles. Indicators revealed a recycling rate of 4.86%, collection coverage of 79.66%, a 0% treatment rate due to the absence of composting or material recovery facilities, and 95% of waste directed to the Final Disposal Site (FDS). These findings demonstrate substantial deficiencies in the current EMS, highlighting that the systematic application of indicators is an effective diagnostic tool for identifying gaps and guiding evidence-based improvements in MSW governance. Full article

Cadmium is an element that is unnecessary for the functioning of plant and animal organisms, and its widespread presence in the environment poses a serious threat to human and animal health. Therefore, effective methods are being sought to remediate soils contaminated with this element, including through the enrichment of degraded soils with organic matter. To this end, the effectiveness of selected organic sorbents, including starch, fermented bark, compost and humic acids, in mitigating the transfer of cadmium and other heavy metals from soil to plants was assessed. Model studies compared the effects of 15 and 30 mg of cadmium (Cd) per kg of soil with an uncontaminated control sample. The sorbents were applied on a carbon basis at a rate of 3 g C per kg of soil. The test plant was Zea mays. Cadmium was found to significantly impair plant growth, causing reductions of 21%, 85%, and 77% in leaf greenness, aboveground biomass and root biomass, respectively. Excess cadmium increased the translocation of lead, chromium, copper, nickel, zinc, iron, and manganese from the roots to the aboveground parts of the plant, while simultaneously limiting their uptake. All of the organic sorbents tested reduced the negative impact of cadmium on leaf greenness, except starch. Compost and HumiAgra significantly improved the condition of Zea mays plants weakened by cadmium exposure. Cadmium contamination increased soil acidification. pH was positively correlated with maize yield and the SPAD leaf greenness index and negatively correlated with the cadmium translocation index and cadmium content in the aboveground parts of maize. Compost and humic acids are among the most effective and practically feasible approaches for reducing cadmium bioavailability in soil and its accumulation in Zea mays, and are therefore recommended for the remediation of cadmium-contaminated soils. Full article

Accurate prediction of compost maturity is vital for ensuring quality, safety, minimum substrate weight loss and agronomic performance of compost products. In this study, eight supervised machine learning (ML) classification models including Random Forest, Logistic Regression, Decision Tree, Gaussian and Multinomial Naive Bayes, K-Nearest Neighbors, Support Vector Machine, and AdaBoost were systematically evaluated for their ability to predict compost maturity using three key indicators: cation exchange capacity (CEC), carbon to nitrogen ratio (C/N), and humic acid (HA) content. A dataset comprising 756 samples (4 composting/vermicomposting systems × 7 treatments × 9 time points × 3 replicates) was generated. To reduce replicate-induced variability and ensure robust machine learning analysis, triplicates were averaged at each time point, resulting in 252 effective observations used for model development. Pearson correlation and heatmap analysis indicated strong interdependencies among CEC, HA, total nitrogen (TN) and organic matter (OM) content, confirming their collective utility in compost maturity classification. Model performance was assessed based on classification metrics (accuracy, precision, recall, F₁-score) and regression-based error indicators, including mean absolute error (MAE), mean squared error (MSE), root mean squared error (RMSE), and coefficient of determination (R²). Ensemble models, particularly RF and AdaBoost, showed the highest predictive accuracy (up to 0.98) and lowest error rates (e.g., MAE < 0.05, RMSE < 0.1, R² > 0.95) when predicting CEC and C/N-based maturity classes. HA-based predictions showed slightly lower precision and higher variance across models. Full article

The large-scale use of compost in arable cropping systems is often limited by the large quantities required to meet the crop’s nutritional needs. Palletization can increase the nutrient density of organic fertilizers and improve their logistical feasibility by reducing storage, transport and application costs. This study evaluated the agronomic and environmental performance of compost pellets derived from pig slurry solids and olive pomace, using them as an alternative nitrogen source for wheat (Triticum aestivum L.) cultivated under Mediterranean conditions. A field experiment was conducted during the 2022–2023 growing season, with four treatments arranged in 24 m² replicated plots: an unfertilized control (C); pelletized compost (PSCOP); fresh pig slurry (PS); and mineral fertilization based on monoammonium phosphate and urea (IN). Excluding the control treatment, all fertilized plots received a uniform nitrogen rate of 150 kg N ha⁻¹. Soil chemical properties and nutrient availability (Pext, NH₄⁺-N and NO₃⁻-N) were evaluated at the beginning and end of the experiment, while wheat yield and grain quality were assessed at harvest. Greenhouse gas (GHG) emissions were monitored throughout the cropping season to evaluate environmental impacts. The results showed that the wheat yields achieved with PSCOP were comparable to those obtained with PS, although they remained lower than those achieved with mineral fertilization. Grain quality was not adversely affected by the application of PSCOP. Furthermore, PSCOP resulted in lower GHG emissions than mineral fertilization, with values closer to those observed in the unfertilized control. These findings suggest that pelletized organic fertilizers such as PSCOP may be a promising way to enhance nutrient circularity and reduce reliance on synthetic fertilizers and maintain crop productivity and limit environmental impact in Mediterranean agricultural systems. Full article