Search Results (747)

Soil health is typically evaluated using physical, chemical, and biological parameters. However, identifying cost-effective and interpretable metrics remains a challenge. The effectiveness of ecological outcome verification (EOV) in predicting soil health in grazing lands was assessed at 22 ranches. Sixty-four soil samples were analyzed using the Haney soil health test (HSHT) and phospholipid fatty acid (PLFA). Of 104 variables, 13 were retained following principal component analysis (PCA), including variables associated with plant community, carbon dynamics, and microbial community structure. Soils with enriched microbial and organic matter (SOM) characteristics supported a healthier ecological status, as corroborated by greater EOV scores. Water-extractable organic carbon (WEOC) was positively correlated to plant functional groups, whereas SOM was positively correlated with plant biodiversity and functional groups. Total bacteria were positively correlated with all EOV parameters. Microbial biomass (MB) was positively correlated with both water and energy cycle indexes, whereas arbuscular mycorrhizal fungi (AMF) was positively correlated with the water cycle. From the multiple regression analyses, water infiltration emerged as a key predictor of soil respiration and WEOC. Overall, the ecological outcomes measured by EOV have the potential to serve as a proxy for soil health, providing a practical tool for producers to make informed land management decisions. Full article

Microplastics currently pose a serious threat to aquatic and terrestrial ecosystems. The high mobility of particles and their diversity in size, material and shape lets them spread widely. Further complicating matters is the ever-expanding plastics industry and modifications to its manufacturing processes. To date, many cases of negative, often toxic effects of microplastics on various species such as fish, birds and mammals have been documented. The methodology for measuring and determining the effects of microplastics on soil organisms is still an area of little understanding and certainly requires further study. In our conducted experiment, we reported the effects of selected microplastics in soil (polyethylene, polyethylene terephthalate, polystyrene, polyamide and a mixture of these plastics) at concentrations of 0.1% w/v and 1% w/v at two time intervals, one and three months, on five different earthworm species, identifying the species-related microplastic response. This study investigated the effects of different microplastics on biological parameters such as survival and respiration and biochemical parameters such as effects on glutathione s-transferase (GST), a marker of detoxification and adaptive response in earthworm species Eisenia andrei, Eisenia fetida, Lumbricus terrestris, Apporectoda caliginosa and Dendrobena veneta. The choices of species and the types of microplastic selected are intended to map the occurrence of microplastic contamination in the soil and determine the adaptation of earthworms to changing environmental conditions, considering their ecological significance and functional diversity in soil ecosystems. Full article

Crop production in plastic greenhouses is one of the major sources of plastic pollution worldwide. The main hypothesis of this study is that the regular use of mulch film in greenhouses leads to the cumulative accumulation of microplastic particles (MPs) in the soil, which ultimately leads to changes in the soil properties. Therefore, the main objective of this study was to identify the possible changes in the physical, chemical, and biological properties of soil in greenhouses in three regions of Serbia. The following chemical parameters were determined: electrical conductivity, soil acidity, cation exchange capacity (CEC), total carbon (TC) and nitrogen (TN) content, plant-available phosphorus and potassium content, and trace element content. The following physical parameters were determined: particle size distribution, volumetric mass, specific mass, and porosity; the biological parameters that were determined were microbial respiration and labile carbon. The obtained data were processed using network analysis (NA) to identify the complex relationships between MP content and soil parameters. The NA results support the main findings that the presence of microplastics leads to the destruction of soil structure, which reduces bulk density and increases soil porosity. A strong positive correlation of MPs with soil particles < 0.02 mm and a negative correlation with CEC were found. In the Danube Valley, soil respiration was 78% higher in the open ground compared to a plastic greenhouse. The results contribute to a better understanding of the influence of MPs on soil properties and its ecological functions. Full article

Biochar application as a soil amendment is gaining attention as a stable, long-term carbon sequestration strategy for the mitigation of climate change. However, biochar applied to the soil may increase soil carbon efflux. This study aimed to determine the long-term (8 years) effects of biochar application to the forest floor on soil carbon effluxes (soil respiration [SR] and heterotrophic respiration [HR]) in a warm–temperate oak forest. Biochar was applied at the rate of 0, 5, or 10 Mg ha⁻¹ to 20 m × 20 m plots (n = 4). The SR and HR rates were determined using the closed chamber method and the trenching method. The annual SR tended to increase over 8 years following biochar application, whereas a significant increase in the annual HR (+31%–37%) was observed in the short term (<3 years). The increased HR likely included CO₂ emissions from the decomposition of the labile fraction of biochar carbon and from the microbial decomposition of the original soil organic matter stimulated through changes in the soil physicochemical environment, such as soil moisture and pH. The results suggest that a short-term increase in HR should be considered in the evaluation of carbon sequestration in response to biochar addition to forest ecosystems. Full article

Background and Methods: We assessed the prokaryotic and eukaryotic diversity present in non-vegetated and vegetated soils on King George Island, Maritime Antarctic, in combination with measurements of carbon dioxide fluxes. Results: For prokaryotes, 381 amplicon sequence variants (ASVs) were assigned, dominated by the phyla Actinobacteriota, Acidobacteriota, Pseudomonadota, Chloroflexota, and Verrucomicrobiota. A total of 432 eukaryotic ASVs were assigned, including representatives from seven kingdoms and 21 phyla. Fungi dominated the eukaryotic communities, followed by Viridiplantae. Non-vegetated soils had higher diversity indices compared with vegetated soils. The dominant prokaryotic ASV in non-vegetated soils was Pyrinomonadaceae sp., while Pseudarthrobacter sp. dominated vegetated soils. Mortierella antarctica (Fungi) and Meyerella sp. (Viridiplantae) were dominant eukaryotic taxa in the non-vegetated soils, while Lachnum sp. (Fungi) and Polytrichaceae sp. (Viridiplantae) were dominant in the vegetated soils. Measured CO₂ fluxes indicated that the net ecosystem exchange values measured in vegetated soils were lower than ecosystem respiration in non-vegetated soils. However, the total flux values indicated that the region displayed positive ecosystem respiration values, suggesting that the soils may represent a source of CO₂ in the atmosphere. Conclusions: Our study revealed the presence of rich and complex communities of prokaryotic and eukaryotic organisms in both soil types. Although non-vegetated soils demonstrated the highest levels of diversity, they had lower CO₂ fluxes than vegetated soils, likely reflecting the significant biomass of photosynthetically active plants (mainly dense moss carpets) and their resident organisms. The greater diversity detected in exposed soils may influence future changes in CO₂ flux in the studied region, for which comparisons of non-vegetated and vegetated soils with different microbial diversities are needed. This reinforces the necessity for studies to monitor the impact of resident biota on CO₂ flux in different areas of Maritime Antarctica, a region strongly impacted by climatic changes. Full article

Biochar (BCH) amendments represent a valuable strategy for increasing forest carbon stock, but their effects on soil respiration of beech forests under climate change are largely unknown. We conducted a short-term mesocosm experiment investigating the impact of BCH applications (0%, 10%, 20%, and 50%, v/v) on respiration of a European beech forest soil in N-Italy. The experiment, carried out in Parma, was conducted under both ambient and modified climatic conditions, involving higher soil temperatures (c. +1 K) and reduced precipitation (−50%). The experiment was performed during autumn 2022 and repeated in spring 2023, periods representing late and early summer, respectively. Soil respiration significantly increased with BCH applications when compared to controls, irrespective of the percentage applied. The highest values were recorded in the 20% amendment, while values were significantly lower in BCH 50%, similar to those recorded in BCH 10%. Although soil respiration and soil temperature were positively correlated, no effect of simulated warming was observed. No effects of precipitation reduction were also found, despite respiration being significantly influenced by soil moisture. These results provide an initial insight into the potentially negligible impact of BCH applications on soil respiration in European beech forests under both current and future climate scenarios. Full article

Carbon dioxide (CO₂) efflux from soil (or soil respiration, SR) is one of the most important yet variable characteristics of soil. When evaluating large areas, CO₂ efflux modeling serves as a viable alternative to direct measurements. This research aims to identify site-specific differences and their effects on empirical CO₂ efflux modeling. The experimental data from 25 years of field observations were utilized to identify the optimal site- and weather-specific models, parameterized for normal, wet, and dry years, for the forest and grassland ecosystems located on similar Entic Podzols (Arenic) in the same bioclimatic coniferous–deciduous forest zone. The following parameters were considered in the examined models: mean monthly soil or air temperatures (Tsoil and Tair), amount of precipitation during the current (P) and the previous (PP) months, and the storage of soil organic carbon (SOC) in the top 20 cm of soil. The weighted non-linear regression method was employed to estimate the model parameters for the normal, wet, and dry years. To increase the magnitude of the model resolutions, we controlled the slope and intercept of the linear model comparison between the measured and modeled data through the change in R₀—CO₂ efflux at Tsoil = 0 °C. The mean bias error (MBE), root-mean-square error (RMSE), and determination coefficient (R²) were employed to assess the quality of the model’s performance. The measured Tsoil, Tair, and P, as well as the litter (for forest) or sod (for grassland) horizon (modeled by the Soil SCLmate Statistical Simulator (SCLISS)), and soil temperatures (Tlit_m, Tsoil_m) and moistures (Mlit_m, Msoil_m), were used for SR simulation. For the CO₂ efflux in the forest ecosystem with the lower SOC availability for mineralization, the direct Tsoil and Tair measurements in combination with SOC storage provided better parameterization for the empirical TPPC model. For the CO₂ efflux in the grassland ecosystem with the high SOC availability for mineralization, the temperature became the governing factor, and the TPPrh model provided better performance over all the considered models. The model’s performance was the best for the wet years, and the worst for the dry years for both ecosystems. For forest ecosystems, the model performance for average precipitation years was equivalent to that in wet years. For grassland ecosystems, however, the model performance was equivalent to that in dry years due to differing exposure and hydrothermal regimes. The wet-year R₀ obtained for both forest and grassland ecosystems differed from the normal- and dry-year values. The measured SR values relevant for the R₀ estimations distribute along the precipitation range for the forest and along the temperature range for the grassland. The SCLISS-modeled Tlit_m and Mlit_m provide good alternatives to direct atmospheric measurements, and can be used as initial temperature and moisture data for CO₂ efflux modeling when direct soil and moisture observations are not available on site. Full article

Phytostabilization of metals involves the inactivation of metals in the soil through the use of various materials as soil amendments, which reduces the bioavailability of metals, and then the introduction of vegetation. There are limited data comparing the effectiveness of different phytostabilization amendments under the same soil and environmental conditions. Therefore, the aim of this research was to compare the effectiveness of a range of soil amendments on reducing the extractability of metals, metal uptake by plants, microbial activity in soil and nutrient availability to plants. Eight materials potentially limiting metal availability were used in a pot experiment: two composts (CG, CM), municipal biosolids (SB), bentonite (BEN), phosphorus fertilizer (PF), amorphous iron oxide (FE), waste rock material (WR), calcium carbonate (LM); and these materials were compared with typical fertilization (NPK) and an untreated soil as the control (CTL). The following trace metal-contaminated soils were used in the pot experiment: soil taken from the area of strong dust fall from the zinc and lead smelter (soil P); soil taken from an outcrop of ore-bearing rocks near a smelter waste heap (soil H); soil artificially polluted through smelter dust spill in the 1990s (soil S). In general, the greatest yields of plants (oat and white mustard) were recorded for compost-treated soils. Changes in the solubility of zinc (Zn) and cadmium (Cd) after the application of various amendments largely reflected changes in soil pH. Biosolids caused a significant increase in extractable Zn and Cd, which was related to the decrease in soil pH, while a significant reduction in Cd extractability was observed across soils after the application of both composts, especially the compost characterized by alkaline pH. Interestingly, low extractability of Cd in the soil with the addition of another compost was observed, despite the pH decrease, as compared to the control pots. This fact proves the high sorption capacity of the compost towards Cd. The microbiological analyses revealed the highly beneficial effect of composts for dehydrogenases and nitrification activities, and for soil respiration, whereas soil amendment with iron oxide caused an increase in respiration activity across soils. Full article

Over time, the vegetation of abandoned rice paddy fields is succeeded by communities of willow (Salix pierotii Miq.). This study was carried out to confirm the potential for future carbon farming by evaluating the carbon absorption capacity of willow communities restored passively in abandoned rice paddy fields. The net primary productivity (NPP) of willow communities established in abandoned rice paddy fields in three areas of central Korea (Cheongju, Andong, and Buyeo) was determined. The NPP was obtained by combining the diameter growth of willow individuals and the density of willow stands, yielding 24.36, 19.74, and 38.69 tons·ha⁻¹·yr⁻¹, respectively, and the average NPP of the three sites was 27.62 tons·ha⁻¹·yr⁻¹. The carbon-based NPP calculated from the average NPP at the three sites was 13.81 tons·C·ha⁻¹·yr⁻¹, and the amount of heterotrophic respiration, which is the respiration of microorganisms and animals in the soil, measured in abandoned rice paddy fields in Cheongju was 5.25 tons·C·ha⁻¹·yr⁻¹. As a result, the net ecosystem production (NEP) of the willow communities established in the abandoned rice paddy fields was calculated as 8.56 tons·C·ha⁻¹·yr⁻¹. By substituting this NEP value into the area of abandoned rice paddy fields so far, the carbon dioxide absorption capacity of abandoned rice paddy fields was estimated to exceed 19 million·tons·yr⁻¹. This amount is high enough to account for 77% of the total forecasted carbon absorption capacity in 2050, which is the year Korea aims to achieve carbon neutrality. In this regard, carbon farming using abandoned rice paddy fields is evaluated as a promising project. Full article

The weathering of carbonate rocks consumes significant amounts of soil CO₂, contributing to both direct source reduction and to the enhancement of carbon sinks. This process holds substantial potential as a carbon sink, making it a critical strategy for achieving carbon neutrality and mitigating climate change. However, the control mechanisms for the reverse assessment of karst carbon sinks, with soil CO₂ as the core at the input end of karstification, are unclear. By comparing soil respiration and its δ¹³C values between karst and non-karst regions, we analyzed the impact of karstification on soil respiration. In this study, we examined the karst grassland (KG), woodland (KW), and non-karst woodland (NKW) in the karst region with identical climate conditions as the research subject, analyzing the differences in soil respiration rate (RS), flux (SRF), and isotope δ¹³C under different land-use types, and comparing them with the non-karst region to reveal the carbon sink potential of karstification in reducing carbon emissions. The results showed that after the land-use change from KG to KW in the karst region, the annual mean values of the RS and SRF increased by 55.50% and 20.94%, respectively. Additionally, the annual mean values of the soil respiration contribution to carbonate weathering in KG were approximately 8.2% higher than those in KW. In contrast, the annual mean values of RS and SRF in KW were 25.14% and 41.80% lower than those in NKW, respectively. Furthermore, the soil respiration participation in carbonate weathering in KW was about 8.9% of that in NKW. Land use change can significantly influence karst carbon sinks, with the KG exhibiting the highest carbon sink capacity. Karst soils play a crucial role in reducing atmospheric CO₂ levels and facilitating regional carbon neutralization. Therefore, the karst systems play a pivotal role in mitigating the “land use change term” (source term, E_LUC) in the global carbon balance. Full article

Iron ore extraction can lead to significant environmental degradation, particularly due to the generation of tailings during the beneficiation process. This issue was highlighted by the B1 dam collapse in Brumadinho, Brazil, in 2019. Therefore, the study and monitoring of affected areas is essential to assess soil quality throughout the rehabilitation process, whether through natural recovery or active rehabilitation practices. Microbial indicators can serve as valuable tools to track the recovery of these areas, given their high sensitivity and rapid response to environmental changes. The aim of this study was to evaluate soil microbial indicators, such as enzyme activity, microbial biomass carbon, microbial basal respiration and microbial diversity, and to select microbial approaches for monitoring the area affected by mining tailings in Brumadinho. The results indicated that the reference area initially outperformed the affected area on all evaluated bioindicators, highlighting environmental stress in the affected zone. Over the course of the study, the two areas began to show greater similarity, suggesting a natural recovery of the soil together with the return of natural vegetation. Indicators such as microbial carbon biomass went from values close to 50 mg of C Kg of soil⁻¹ in the affected area, to around 200, statistically equal to the reference. qCO₂ also varied in the affected area to values statistically equal to those of the reference over time, variated in the first collection to 0.25 mg of C-CO₂ mg of C⁻¹ h⁻¹ in the affected area against 0.1 in the reference area; in the last collection, both areas presented values close to 0.2. Enzymatic activity had superior values in the reference area about the affected area, being urease, and arylsulfatase more sensitive to show differences between areas over time. The metataxonomic data again revealed indicator species for each environment, including genera such as Bacillus, Mycobacterium, Acidibacter, and Burkholderia representative of the reference, and the genera Ramlibacter, Sinomonas, Psedarthrobacter, and Knoellia indicators of the affected area. By the end of this study, the applicability of microbial indicators for monitoring soil microbiota and its ecosystem services was successfully demonstrated. In addition, specific microbial indicators were proposed for monitoring areas affected by iron mining tailings. Full article

Zanthoxylum planispinum var. Dingtanensis (hereafter Z. planispinum) has excellent characteristics, including Ca and drought tolerance. It can flourish in stony soils, and it is used as a pioneer plant in karst rocky desertification control. However, soil degradation, coupled with the removal of nutrients absorbed from the soil by Z. planispinum’s fruit harvesting, exacerbates nutrient deficiency. The effects of fertilization on soil nutrient utilization and microbial limiting factors remain unclear. Here, we established a long-term (3 year) field experiment of no fertilization (CK), organic fertilizer + chemical fertilizer + sprinkler irrigation (T1), chemical fertilizer + sprinkler irrigation (T2), chemical fertilizer treatment (T3), and leguminous (soybean) + chemical fertilizer + sprinkler irrigation (T4). Our findings indicate that fertilization significantly improved the nutrient uptake efficiency of Z. planispinum, and it also enhanced urease activity compared with CK. T1 increased soil respiration and improved water transport, and the soil nutrient content retained in T1 was relatively high. It delayed the mineralization rate of organic matter, promoted nutrient balance, and enhanced enzyme activity related to the carbon and nitrogen cycle. T4 caused soil acidification, reducing the activity of peroxidase (POD) and polyphenol oxidase (PPO). The soil microbial community in the Z. planispinum plantation was limited by carbon and phosphorus, and T1 mitigated this limitation. This study indicated that soil nutrient content regulated enzymatic activity by influencing microbial resource limitation, with organic carbon being the dominant factor. Overall, we recommend T1 as the optimal fertilization strategy for Z. planispinum plantations. Full article

Accurately partitioning evapotranspiration (ET) of cropland into productive plant transpiration (T) and non-productive soil evaporation (E) is important for improving crop water use efficiency. Many methods, including machine learning methods, have been developed for ET partitioning. However, the applicability of machine learning models in cropland ET partitioning with diverse crop rotations is not clear. In this study, machine learning models are used to predict E, and T is obtained by calculating the difference between ET and E, leading to the derivation of the ratio of transpiration to evapotranspiration (T/ET). We evaluated six machine learning models (i.e., artificial neural networks (ANN), extremely randomized trees (ExtraTrees), gradient boosting decision tree (GBDT), light gradient boosting machine (LightGBM), random forest (RF), and extreme gradient boosting (XGBoost)) on partitioning ET at 16 cropland flux sites during the period from 2000 to 2020. The evaluation results showed that the XGBoost model had the best performance (R = 0.88, RMSE = 6.87 W/m², NSE = 0.77, and MAE = 3.41 W/m²) when considering the meteorological data, ecosystem sensible heat flux, ecosystem respiration, soil water content, and remote sensing vegetation indices as input variables. Due to the unavailability of observed E or T data at the 16 cropland sites, we used three other widely used ET partitioning methods to indirectly validate the accuracy of our ET partitioning results based on XGBoost. The results showed that our T estimation results were highly consistent with their T estimation results (R = 0.83–0.91). Moreover, based on the XGBoost model and the three other ET partitioning methods, we estimated the ratio of transpiration to evapotranspiration (T/ET) for different crops. On average, maize had the highest T/ET of 0.619 ± 0.119, followed by soybean (0.618 ± 0.085), winter wheat (0.614 ± 0.08), and sugar beet (0.611 ± 0.065). Lower T/ET was found for paddy rice (0.505 ± 0.055), winter barley (0.590 ± 0.058), potato (0.540 ± 0.088), and rapeseed (0.522 ± 0.107). These results suggest the machine learning models are easy and applicable for cropland T/ET estimation with different crop rotations and reveal obvious differences in water use among different crops, which is crucial for the sustainability of water resources and improvements in cropland water use efficiency. Full article

Global climate change is closely tied to CO₂ emissions, and implementing conservation-agricultural systems can help mitigate emissions in the Amazon. By maintaining forest cover and integrating sustainable agricultural practices in pasture, these systems help mitigate climate change and preserve the carbon stocks in Amazon forest soils. In addition, these systems improve soil health, microclimate regulation, and promote sustainable agricultural practices in the Amazon region. This study aimed to evaluate the CO₂ emission dynamics and its relationship with soil attributes under different uses in the Amazon. The experiment consisted of four treatments (Degraded Pasture—DP; Managed Pasture—MP; Native Forest—NF; and Livestock Forest Integration—LF), with 25 replications. Soil CO₂ emission (FCO₂), soil temperature, and soil moisture were evaluated over a period of 114 days, and the chemical, physical, and biological attributes of the soil were measured at the end of this period. The mean FCO₂ reached values of 4.44, 3.88, 3.80, and 3.14 µmol m⁻² s⁻¹ in DP, MP, NF, and LF, respectively. In addition to the direct relationship between soil CO₂ emissions and soil temperature for all land uses, soil bulk density indirectly influenced emissions in NF. The amount of humic acid induced the highest emission in DP. Soil organic carbon and carbon stock were higher in MP and LF. These values demonstrate that FCO₂ was influenced by the Amazon land uses and highlight LF as a low CO₂ emission system with a higher potential for carbon stock in the soil. Full article

Plastic pollution has become a major environmental problem, while the products of its degradation, microplastics (MPs), appear everywhere on Earth. Data on MPs in agricultural soils have appeared lately, but a significant knowledge gap exists regarding forest soils. In Serbia, municipal waste is often dumped in forests, creating environmental problems that have not been documented. To explore the impact of waste dumping and MPs on forest fluvisols, we evaluated MPs from topsoils of three waste dumps and adequate visibly plastic non-contaminated forest sites located in alluviums of the largest rivers in Serbia. For assessing the influence of environmental factors on soil MPs, samples were taken in three forest vegetational seasons, in two years. The impact of MPs on soil structure, chemistry, and microbial respiration (MR) was examined. Undisturbed soil columns from uncontaminated sites with added known MP particles were used to estimate the dynamic of MP transfer through the topsoil. Large aggregate formation, soil coarse sand content, specific mass, porosity, and available P, but not MR were affected by contamination. Seasonal and annual environmental changes significantly influenced the behavior of MPs in forest luvisols. MPs effectively penetrated the deeper layers of soil columns within 3 months, with strong accumulation in the 0–10 cm layer. Full article