Soil Recovery Research Articles

Sustainable Restoration of Soil Functionality in PTE-Affected Environments: Biochar Impact on Soil Chemistry, Microbiology, Biochemistry, and Plant Growth

Biochar can be useful for the functional recovery of soils contaminated with potentially toxic elements (PTEs), even if its effectiveness is variable and sometimes limited, and conflicting results have been recently reported. To shed some light on this regard, softwood-derived biochar was added at 2.5 (2.5-Bio) and 5.0% w/w (5.0-Bio) rates to an acidic (pH 5.74) soil contaminated by Cd (28 mg kg−1), Pb (10,625 mg kg−1), and Zn (3407 mg kg−1). Biochar addition increased soil pH, available P and CEC, and reduced labile Cd, Pb, and Zn (e.g., by 27, 37, and 46% in 5.0-Bio vs. the unamended soil). The addition of biochar did not change the number of total heterotrophic bacteria, actinomycetes, and fungi, while it reduced the number of Pseudomonas spp. and soil microbial biomass. Dehydrogenase activity was reduced in amended soils (e.g., by ~60 and 75% in 2.5- and 5.0-Bio, respectively), while in the same soils, urease increased by 48 and 78%. Approximately 16S rRNA gene amplicon sequencing and the Biolog community-level physiological profile highlighted a significant biochar impact (especially at a 5% rate) on soil bacterial diversity. Tomato (but not triticale) yield increased in the amended soils, especially in 2.5-Bio. This biochar rate was also the most effective at reducing Cd and Pb concentrations in shoots. Overall, these results demonstrate that 2.5% (but not 5.0%) biochar can be useful to restore the soil chemical fertility of PTE-polluted soils with limited (or null) impact on soil microbial and biochemical parameters.

Biological Application of the Allopathic Characteristics of the Genus Maclura: A Review.

Maclura is a plant genus little known and used, species of which have been mainly used in the recovery of soils, for medicinal purposes such as dental infection treatments, and as wood for making furniture and construction. The overexploitation of this genus has placed certain species in endangered extinction status in some countries, such as Brazil. In addition, the scarce research and information limit the development, cultivation, and management of its species regarding their biochemical composition, which includes bioactive compounds such as the phenolic and flavonoid compounds found in some species such as M. pomifera, M. cochinchinensis, and M. tinctoria. The plants' antioxidant, antimicrobial, anticancer, anti-inflammatory, and antiproliferative activities have been attributed to these compounds. Other biochemical components such as ashes, insoluble lignin, holocellulose, and the high content of lipids and carbohydrates have been identified to be used to produce biofuels, with characteristics very similar to fuels derived from petroleum. This review aims to analyze the current knowledge on the plant genus Maclura, exploring its biochemical compounds and potential applications, including as a food additive, antioxidant supplement, in agriculture, for therapeutic purposes, aquaculture, and the cosmetic and industrial sector.

Surface soil recovery occurs within 25 years for skid trails in the Brazilian Amazon

Each year, thousands of km2 of humid tropical forest are logged in the Brazilian Amazon. Many of these areas are underlain by clay soils dominated by non-expansive kaolinite. Logging operations often entail the use of heavy machinery to drag logs through the forest on skid trails, which causes substantial soil disturbance. Therefore, the objective of this study was to investigate if soil recovery occurs over time in the studied Ferralsol. The hypothesis is that soil recovery has indeed occurred and that the trend of recovery is observable. In this endeavor, a chronosequence was established composed of four logging units that were logged 13, 19, 23, and 26 years ago, as well as a control in undisturbed old-growth forest. Samples in the upper topsoil were collected for soil bulk density (BD), fine root biomass (FRB) and various soil chemical properties. Results indicated a sequential recovery. Prior to the study period of 13–26 years after logging operations, FRB recovered. The predicted recovery of the cation exchange capacity was at approximately 15 years, which was followed by soil organic carbon at 20 years. Lastly, BD was recovered within 25 years. Overall, soil organic carbon demonstrated the greatest associations with recovery variables as it accumulated over time. Although surface soils in skid trails did indeed recover, it was a lengthy process that occurred over several decades. In this context, skid trails should be planned to minimize soil disturbance in the logging area to the greatest extent feasible.

Facile microplastic recovery in soil using temperature-driven phase transition of saturated fat: Optimization and evaluation

Extracting microplastics (MPs) from soil matrices is challenging due to their heterogeneous distribution and the lack of standardized recovery techniques. Addressing this, we introduce a cost-effective and eco-friendly method utilizing the temperature-driven phase transitions of saturated fats for efficient and accurate MP separation. Among the evaluated saturated fats - butter, lard, and coconut oil - coconut oil demonstrated a 100% recovery of five MP types (LDPE, PP, PS, PET, and PTFE) from soil across three consecutive cycles, owing to its solidification characteristics. The process was further examined by exploring the effects of agitation force and soil texture (sea sand and agricultural soil), where agitation force impacted efficiency, while soil texture remained insignificant. The technique utilizing coconut oil demonstrated high matrix retaining efficiencies for both soil matrices, signifying its ability to separate MPs without soil contamination. To ensure MPs' integrity, isopropanol was used for solidified coconut oil removal, which did not alter the MPs' pristine state, as validated by microscopy, FTIR spectroscopy, and Py-GC/MS. In comparison to prior methods, our approach significantly reduces both operating costs and environmental impact. Overall, our study paves the way for a sustainable and affordable solution to MP contamination in soils.

Cultivation of Melilotus officinalis as a source of bioactive compounds in association with soil recovery practices.

Melilotus officinalis is a Leguminosae with relevant applications in medicine and soil recovery. This study reports the application of Melilotus officinalis plants in soil recovery and as a source of bioactive compounds. Plants were cultivated in semiarid soil under four different fertilizer treatments, urban waste compost at 10 t/ha and 20 t/ha, inorganic fertilizer and a control (no fertilizer). Agronomic properties of soil (pH, EC, soil respiration, C content, macro- and microelements) were analyzed before and after treatment. Also, germination, biomass, element contents, and physiological response were evaluated. Metabolite composition of plants was analyzed through Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Results showed a significant enhancement of the soil microbial activity in planted soils amended with compost, though there were no other clear effects on the soil physicochemical and chemical characteristics during the short experimental period. An improvement in M. officinalis germination and growth was observed in soils with compost amendment. Metabolite composition of plants was analyzed through Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Principal Component and Agglomerative Hierarchical Clustering models suggest that there is a clear separation of the metabolome of four groups of plants grown under different soil treatments. The five most important discriminative metabolites (annotated) were oleamide, palmitic acid, stearic acid, 3-hydroxy-cis-5-octenoylcarnitine, and 6-hydroxynon-7- enoylcarnitine. This study provides information on how the metabolome of Melilotus might be altered by fertilizer application in poor soil regions. These metabolome changes might have repercussions for the application of this plant in medicine and pharmacology. The results support the profitability of Melilotus officinalis cultivation for bioactive compounds production in association with soil recovery practices.

Microbial attributes as structural quality index for physical health of an Oxisol under compaction levels

Microbial activity is a sensitive indicator of soil structure improvement provided by plant species in the physical recovery of compacted soils. This study aimed to assess the impacts of crop species on soil aggregate classes for soil recovery after compaction and identify which microbial attributes best describe the structural quality index for soil physical health in an Oxisol under no-tillage. The experiment comprised three crop species—maize, ruzigrass, and black oats—cultivated under four degrees of compactness produced by chiseling or machine traffic under long-term no-tillage. Soil aggregates were separated by dry sieving into five diameter classes to assess the basal respiration, microbial biomass carbon, metabolic quotient for CO2 (qCO2), labile carbon, cellulase activity, and total organic carbon. The values of microbial indicators for the bulk soil were estimated as a weighted mean of each attribute using aggregate size distribution. The lowest values for total organic carbon, labile carbon, and microbial biomass carbon were observed in aggregates > 4 mm. The basal respiration values increased from 8.2 µg C-CO2 g d−1 in the aggregates > 4 mm, to 22.1 µg C-CO2 g soil d−1 in the aggregates < 0.5 mm (+170%). Similarly, the cellulase activity increased approximately four times comparing aggregates > 4 mm (38 µg glucose g−1 d−1) to those < 1 mm (181 µg glucose g−1 d−1). The total organic carbon and microbial biomass carbon were found to be little affected by crops. However, the plots cultivated with black oats or ruzigrass exhibited higher cellulase activity, basal respiration, and qCO2 in comparison with maize, primarily due to the greater content of labile carbon. Increasing the mean weight diameter from 3 mm to 8 mm led to a decrease in the labile carbon (−27.4%), microbial biomass carbon (−25.5%), cellulase activity (−70%), and basal respiration (−21.6%), thereby revealing negative effects of soil compaction on microbial attributes. The degree of compactness did not influence the values of total organic carbon and qCO2. The response of the microbial indicators depends on the aggregate diameter classes. The results of this study indicate that cultivation of cover crops decreases the negative impacts of soil structure degradation on soil microbial quality. Cellulase activity and labile carbon were considered as new potential indicators of soil compaction for soil physical health studies—highly sensitive and quickly responsive to managements that induce soil structure changes in an Oxisol.

The effects of terrestrial dissolved organic matter on phytoplankton biomass and productivity in boreal lakes

Abstract Allochthonous dissolved organic matter (DOM) structures many physical, chemical, and biological properties of lakes including key variables that control productivity at the base of freshwater food webs. A growing number of studies have documented increasing DOM concentrations within lakes across Europe and North America, including boreal lakes. Such increases are associated with the recovery of catchment soils from acid rain and rising precipitation linked to climate change. We examined phytoplankton biomass, productivity, and their drivers across eight pristine boreal lakes with DOM ranging from 3.5 to 9.5 mg dissolved organic carbon/L. Physical and chemical properties were assessed using standard limnological methods. Phytoplankton biomass was assessed using both chlorophyll a (Chl‐a) and via microscopy. Phytoplankton productivity was assessed using change in partial pressure of carbon dioxide within in vitro incubations. Increases in DOM were associated with significant increases in epilimnetic nitrogen, phosphorus and Chl‐a concentrations suggesting that nutrients associated with DOM stimulated phytoplankton biomass and productivity. Such results were misleading; there was no significant relationship between Chl‐a and phytoplankton biomass. Chl‐a:biomass and Chl‐a:carbon ratios indicated that increases in Chl‐a with DOM were driven by photo‐acclimation to declining light availability. Further, results presented as epilimnetic concentrations would not account for concurrent declines in thermocline depth or euphotic depth driven by DOM. Increases in DOM led to large declines in thermocline (c. 50%) and euphotic (c. 75%) depths, and depth‐integrated phytoplankton biomass (c. 70%) and primary production (c. 70%). Our results indicate that DOM plays a structuring role for key physical, chemical, and biological properties of lakes, including productivity, at a landscape level. Further, practitioners should be cautious when using Chl‐a as an indicator of phytoplankton biomass in studies using DOM or water clarity gradients, report results using depth integrated units due to changes in volumes of thermal layers induced by DOM, and incorporate estimates of sub‐epilimnetic productivity when evaluating DOM effects.

Temporal and Spatial Dynamics of Bacterial and Fungal Microbiomes in Nursery Soils Post-Steaming

A major concern for plant nurseries and land stewards is managing pathogens that induce soilborne diseases. Plant diseases cost nurseries millions of dollars in lost revenue and plant pathogens spread into the environment from nursery soil used for out-plantings. Recent research shows that steaming soil at high temperatures can effectively kill plant pathogens; however, few studies have investigated the influence of steaming on the soil microbiome, an essential component of plant health. We conducted a controlled experiment where nursery soil underwent a steaming event within a rectangular mesocosm (2.04 × 3.55 × 0.25 m) located at the National Ornamentals Research Site at Dominican University (NORS-DUC) (San Rafael, CA, U.S.A.). Soil samples were collected at four time points post-steaming. Thirty-two soil samples were used for DNA extraction and 18 for chemical analysis. The 16S rRNA gene and ITS genetic markers were used for amplicon-based sequencing to identify the bacterial and fungal soil communities. Results indicate that microbial diversity and composition shifted over time but that soil depth was not an important factor. Important bacterial taxa were the Firmicutes, especially 1 day post-steaming, and common fungal taxa included Aspergillus sp., Cladosporium sp., and Pseudallescheria sp. Plant nutrients such as B, C, Cl, K, Mg, SO4, and Zn, in addition to essential soil properties such as CEC, gypsum, moisture, and SAR, changed significantly with soil recovery. These results can help nursery practitioners make informed decisions for biotic and nutrient amendments post-steaming to promote soil and plant health. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Short-term responses of the soil microbiome and its environment indicate an uncertain future of restored peatland forests

Restoring peatland ecosystems involves significant uncertainty due to complex ecological and socio-economic feedbacks as well as alternative stable ecological states. The primary aim of this study was to investigate to what extent the natural functioning of drainage-affected peat soils can be restored, and to examine role of soil microbiota in this recovery process. To address these questions, a large-scale before-after-control-impact (BACI) experiment was conducted in drained peatland forests in Estonia. The restoration treatments included ditch closure and partial tree cutting to raise the water table and restore stand structure. Soil samples and environmental data were collected before and 3–4 years after the treatments; the samples were subjected to metabarcoding to assess fungal and bacterial communities and analysed for their chemical properties. The study revealed some indicators of a shift toward the reference state (natural mixotrophic bog-forests): the spatial heterogeneity in soil fungi and bacteria increased, as well as the relative abundance of saprotrophic fungi; while nitrogen content in the soil decreased significantly. However, a general stability of other physico-chemical properties (including pH remaining elevated by ca. one unit) and annual fluctuations in the microbiome suggested that soil recovery will remain incomplete and patchy for decades. The main implication is the necessity to manage hydrologically restored peatland forests while explicitly considering an uncertain future and diverse outcomes. This includes their continuous monitoring and the adoption of a precautionary approach to prevent further damage both to these ecosystems and to surrounding intact peatlands.

Application of a Soil Quality Index to a Mediterranean Mountain with Post-Fire Treatments

In Mediterranean areas, fire has increased soil degradation and erosion. For this reason, the application of soil quality indices can help to determine soil recovery and degradation levels. By using a multiparameter soil quality index fitted to undisturbed forest soils, we can show the right information on soil functionality. In this study, the objectives were to evaluate soil functionality after suffering a fire, to subsequently treat with various soil treatments (wood mulching), and then check a soil quality index (SQI) to assess the soil quality recovery in burned Pinus nigra stands. For this purpose, a burned area was selected in the Cuenca Mountain range (Spain) under a Mediterranean climate. Experimental plots were established in the study area, with three slope gradients and applying three methods of covering soil using: (1) wood chips; (2) piles of branches; and (3) trunks of contour-felled logs. The experiment was conducted for 4 years. Results showed that the properties of soil were enhanced under wood chips and logs as a surface-covering material, and in a short time (less of 3 years). In consequence, the values of the SQI index were higher after applying these two treatments, thus reflecting the effectiveness of the SQI for monitoring post-fire recovery.

Nitrogen dynamics after slurry application as affected by anaerobic digestion, biochar and a nitrification inhibitor

AbstractAnimal manures are valuable multi‐nutrient fertilizers, but their short‐term nitrogen (N) use efficiency (NUE) by plants is low, bearing the potential of harmful N losses to the environment, such as nitrate () leaching. To develop strategies to increase the NUE of cattle slurry, a comprehensive understanding of slurry N dynamics in the soil–plant system is needed. In a 57‐day microcosm experiment in the greenhouse, we assessed the effect of different slurry treatments on slurry N turnover in the soil and its uptake by ryegrass (Lolium multiflorumvar. Westerwoldicum). Employing a two‐factorial design,15N cattle slurry (SLU),15N anaerobically digested cattle slurry (SLA), and15N anaerobically digested cattle slurry plus biochar (SLA+) were combined with and without the nitrification inhibitor 3,4‐dimethyl‐1H‐pyrazole monophosphate (DMPP). As references, a mineral fertilizer (MIN) and an unfertilised treatment (N0) were included. The15N recovery, hence NUE, in plant biomass was higher for SLA than for SLU, while recovery in soil at 55 days after set‐up showed an opposite trend, with over 45% of N from SLU still being recovered in soil. DMPP and biochar only marginally affected NUE and fertilizer N recovery in soil. Although15N recovery in soil was highest for SLU, residual N leaching from SLU was low (&lt;1% of added N). We attribute this to the limited presence of slurry N in mineral forms at this point of time, with the majority being stored in the non‐microbial organic soil N pool. Leaching of residual N from MIN was significantly higher for MIN than for SLU, while SLA and SLA+ ranged in between. Overall, anaerobic digestion appeared suitable for increasing NUE of cattle slurry, but further investigations under field conditions are necessary in order to assess its potential to reduce nitrate leaching in the long‐term.

Индикаторы эколого-биологического состояния нефтезагрязненной дерново-подзолистой почвы

Oil pollution adversely affects the ability of soils to perform ecological functions. An experiment was conducted that simulated the contamination of Umbric albeluvisols with crude oil, followed by reclamation for three months against the background of loosening, liming and application of biologics. The content of residual oil products, pH, amount of mobile phosphorus and potassium compounds, catalase and urease activity were analyzed in the soil. The reaction of watercress to the soil condition was traced by changes in the length and weight of the above-ground part, protein accumulation, and redox activity. The phytotesting data correlated with the content of residual oil products and can serve as indicators of the contaminated soil recovery process. The integral ecological and biological indicator of the soil is calculated on the basis of the mathematical optimization method; the most successful recovery of ecological functions of oil-contaminated soil developed on the background of loosening and liming. Keywords: SOIL QUALITY, INDICATORS OIL POLLUTION, RECULTIVATION, PHYTOTESTING, UMBRIC ALBELUVISOLS

Combined Use of a Bacterial Consortium and Early-Colonizing Plants as a Treatment for Soil Recovery after Fire: A Model Based on Los Guájares (Granada, Spain) Wildfire.

During 2022, intense heat waves, together with particularly extreme dry conditions, created a propitious scenario for wildfires, resulting in the area of vegetation consumed in Europe doubling. Mediterranean countries have been particularly affected, reaching 293,155 hectares in Spain, the worst data in the last 15 years. The effects on the vegetation and the soil are devastating, so knowing the recovery factors is essential for after-fire management. Resilient microorganisms play a fundamental role in rapid nutrient recycling, soil structure, and plant colonization in fire-affected soils. In this present work, we have studied emergent microbial communities in the case of the Los Guájares (Granada, Spain) fire, one of the most extensive of the year, to evaluate their role in the recovery of soil and vegetation cover. We aim to discern which are the main actors in order to formulate a new treatment that helps in the ecosystem recovery. Thus, we have found the relevant loss in phosphorous and potassium solubilizers, as well as siderophores or biofilm producers. Here, we decided to use the strains Pseudomonas koreensis AC, Peribacillus frigoritolerans CB, Pseudomonas fluorescens DC, Paenibacillus lautus C, Bacillus toyonensis CD, and Paenarthrobacter nitroguajacolicus AI as a consortium, as they showed most of the capacities required in a regenerative treatment. On the other hand, the microcosm test showed an enhanced pattern of germination of the emerging model plant, Bituminaria bituminosa, as well as a more aggregated structure for soil. This new approach can create a relevant approach in order to recover fire-affected soils in the future.

First assessment of soil mesofauna, microbiota, and humic substances associations in a minesoil revegetated with four grasses in Brazil: An 18-year field study

Moving away from coal protects our environment and soil. However, coal use in 2022 exceeded all previous years, systematically generating minesoils. The reestablishment of vegetation and organisms in minesoils is jeopardized by excessive soil compaction, eventual acidity, and depletion of soil organic matter (SOM), fauna, and microbial communities. Therefore, monitoring the recovery of soil attributes and functions as influenced by revegetation species is crucial to understanding the processes and time of ecological restoration. We aimed to verify if 18 years of revegetation with perennial grasses (Hemarthria altissima, Paspalum notatum, Cynodon dactylon, Urochloa brizantha) transformed the minesoil a habitat for mites, springtails and other invertebrates as well as for soil microorganisms. Moreover, we investigated associations between these biological indicators with soil humic substances (HS) content. The minesoil is located in Candiota (Brazil), and was constructed in 2003, when revegetation with the grasses started. In 2021, soil samples (0.10 m depth) were collected to determine mites and springtails abundance, microbial respiration, carbon and metabolic quotient, soil, HS content, pH, bases, and aluminum saturation. In order to monitor the soil attributes recovery by the perennial grasses, the means of treatments were compared to the control using percentage differences (positive or negative), as the control was not part of the experimental design. The relationship between the biological variables and the soil variables was assessed using Spearman correlation, and the Canonical Correspondence Analysis was used to identify the performance of each grass in relation to the dataset. The associations observed confirm that the minesoil recovery process is still in its initial, mainly between soil biological functions with SOM humification. Positive associations occurred between mites and microbial respiration and accumulation of humin, especially with Urochloa brizantha revegetation.

Microbial, physical and chemical indicators together reveal soil health changes related to land cover types in the southern European sites under desertification risk

Soil microbial communities, which play a key role in the provision of essential ecosystem services, are significantly influenced by several physical and chemical soil properties that may change with land management. This study explores the effect of different land cover types (coniferous tree stands, broad-leaved stands, shrublands, pastures/grasslands and croplands) on physical, chemical and microbial properties (all contributing to soil health) in southern European areas under moderate-high desertification risk selected in Italy, Spain and Portugal. In sites that differ in land cover, we determined microbial biomass (Cmic), activity and indices of microbial metabolism including Cmic/Corg ratio, metabolic quotient (qCO2) and quotient of mineralization (qM). Soil physical and chemical properties were also measured, comprising bulk density (BD), water content (WC), pH, cation exchange capacity (CEC), total organic C (Corg) and some of its labile fractions, extractable C (Cext) and mineralizable C (Cmin), total N content and C/N. Results showed that land cover type played a strong role in determining magnitude of microbial variables with biomass and activity being higher under coniferous tree cover than in other land covers, according to trends in WC, CEC, Corg, Cext, Cmin, N, C/N. Compared to land cover, aridity index had lower effect on investigated variables. In comparison to sites with higher Corg content, sites with lower Corg content (most croplands) tended to lose C more rapidly, as suggested by high qM values, except for Spanish acidic soils. Therefore, urgent actions must be taken to counteract the tendency of C-poorer soils to lose C, promoting land cover types that facilitate soil recovery by ensuring denser and more continuous soil cover over time. We also identified a minimum set of soil variables that provide information on soil health changes in both short term (microbial variables) and longer term (physical and chemical variables) in areas under desertification risk.

Effects of sample mass and suspension salinity on particle size distribution in predominantly medium to heavy textured soils using the hydrometer method

AbstractBackgroundParticle size distribution (PSD) is a fundamental soil measurement that is crucial for agriculture, engineering, hydrological, and environmental applications as well as in basic research such as in developing water release curves in flow and transport modeling. The accurate determination of PSD, particularly clay content, is especially critical in ascertaining the magnitude and rates of many physical, chemical, and hydrological processes in soils. The accuracy of the hydrometer method for PSD, which relies on the settling velocity of soil particles in a soil suspension, could be affected by the density of the suspension, which in turn, depends on the initial sample mass, texture, and mineralogy of the soil.AimsWe hypothesized that (1) initial mass determines the concentration and the physical interaction of particles in a soil suspension and affects particle settlement, recovery, and the accuracy of the hydrometer method, and (2) the widely used initial air‐dry mass of 50 g underestimates the clay percentage of medium to heavy textured tropical soils. The objective of this study was to investigate the effect of mass and KCl on clay recovery in tropical soils with varying texture and mineralogy using the hydrometer method.MethodsThe experiment comprised seven soils, four soil masses (10, 20, 30, 50 g), and two KCl treatments in a 7 × 4 × 2 factorial design replicated three times.ResultsResults showed a general trend of increasing estimates of clay % as the soil mass decreased from 50 to 10 g and the KCl concentration increased from 0 to 0.0025 M. This implies that using an initial sample mass of 50 g in sedimentation methods, underestimates, and 10 g overestimates the clay % in predominantly medium to heavy textured tropical soils. Interestingly, there was a drastic change in texture for most of the soils as the sample mass decreased to 10 g.ConclusionsWe conclude that the initial air‐dry mass affects the clay recovery of medium to heavy textured humid tropical soils. Results suggest that the ideal initial mass for these soils lies between 20 and 30 g. Furthermore, the mechanistic pathway that drives the observed decrease in clay recovery as soil sample mass increase could be due to the flocculating tendency of KCl.

Acidity of Soil and Water Decreases in Acid-Sensitive Forests of Tropical China.

Acid deposition in China has been declining since the 2000s. While this may help mitigate acidification in forest soils and water, little is known about the recovery of soils and water from previous severe acidification in tropical China. Here, we assessed the chemistry of mineral soils, water, and acid gases (SO2 and NOx) from three successional forest types in tropical China from 2000 to 2022. Our results showed that soil pH increased synchronously from 3.9 (2000-2015) to 4.2 (2016-2022) across all three forest types, with exchangeable acid initially decreasing and thereafter stabilizing. Surface and ground water pH also gradually increased throughout the monitoring period. Soil pH recovery was stronger in the primary than in the planted forest. However, soil pH recovery lagged behind the increase in rainfall pH by approximately a decade. The recovery of soil pH was likely related to the positive effects of the dissolution of Al/Fe-hydroxysulfate mineral and subsequent sulfur desorption on soil acid-neutralizing capacity, increased soil organic matter, and climate warming, but was likely moderated by increased exchangeable aluminum and potentially proton-producing hydroxysulfate mineral dissolution that caused the lagged soil pH recovery. Surface and ground water pH recovery was attributed to increased water acid-neutralizing capacity. Our study reports the potential for the recovery of acidified soil and water following decreased acid deposition and provides new insights into the functional recovery of acid-sensitive forests.

Rendzinas of the Russian Northwest: Diversity, Genesis, and Ecosystem Functions: A Review

Rendzinas in the taiga zone are intrazonal soils; moreover, all of their processes occur in ways that are different from podzolic soil formation, which is typical for the zonal taiga boreal ecosystem. At the same time, the habitats of carbonate soils are known as places in which there is a concentration of biodiversity in the more southern regions, as they are drier, are insolated, and have a higher trophic state than zonal podzols. The biotopes on carbonate soils are becoming more southern and are dominated by nemoralis species of flora, including abundant calciphilous plant species. Carbonate soils regulate biogeochemical processes within their distribution and in the geochemically subordinate landscapes of Northwest Russia. They are associated with the existence of a number of specially protected natural areas, as well as the implementation of a number of important ecosystem services. Carbonate soils of the southern taiga are endangered and require special protection. The belt of the carbonate soils in the northwestern Russian and Baltic regions extends to Poland and is the basis for the formation of a special landscape–ecological framework with specific biodiverse, biogeochemical, and geographical characteristics. The intensive extraction of limestone from quarries leads to the destruction of rendzinas, which makes them increasingly rare and extremely vulnerable. The rate of recovery of rendzina soils after technogenic impacts is much slower than the regeneration of zonal podzols; therefore, they are an almost non-renewable resource. Thus, rendzinas are an important component of the Northwest Russian soil cover, where all factors of soil formation “refract” and acquire specificity, leading to radical changes not only in the soil-forming potential of the environment but in all of the components of terrestrial ecosystems. In other words, the island of alkaline rocks inherited from the ancient seas is currently pedogeochemically actualized in the soil cover of vast taiga areas.

Evaluating How Enhanced Efficiency Nitrogen Fertilizers Improve Agricultural Sustainability: Greenhouse Multi-Phase Tracking System

The vast consumption of nitrogen-based fertilizers is a significant source of environmental pollutants in all phases. While enhanced-efficiency nitrogen fertilizers (EENFs) improve N-use efficiency and reduce environmental impact, their performance depends on local conditions. Here, we present a relatively simple soil–fertilizer–plants greenhouse setup for the multi-phase tracking of N species of the effects of EENFs. We compared the environmental and agronomic performance of three urea-based EENFs (urea embedded with urease inhibitors, 2-month, and 4-month controlled release urea) and the common split surface application of the granulated urea. We tested the fertilizer applications on basil seedlings for three consecutive growing cycles. The analyses carried out included nitrogen recovery in plant biomass, soil, drainage, and NH3 and N2O emissions. This multi-phase research indicates that tested EENFs perform better than the standard surface-applied urea. The four-month controlled-release urea fertilizer matched the basil N demand the best, significantly increasing yield and improving nitrogen use efficiency while reducing NO3− leaching and NH3 and N2O emissions. The presented soil–fertilizer–plants experimental setup provides a relatively easy-to-handle system for the comprehensive tracking of N dynamics, including plant response. It allows stakeholders to estimate and improve fertilization sustainability.

Post-fire wood mulch negatively affects the moss biocrust cover and its positive effects on microbial diversity in a semi-arid Mediterranean forest

Mulches are highly effective in mitigating the risk of erosion generated after wildfires in fire-prone ecosystems. Despite being a technique commonly used, it remains completely unexplored how mulches interact with the positive effects of the emergent moss biocrust on the recovery and resilience of soils and their microbial communities. For this purpose, the effects of wood-based mulch were assayed on the soil stability and moisture improvement, the nutrient inputs, and the response of microbial biomass, activity, composition, and diversity. Soils were studied after one year of wood mulch application at two rates representing possible scenarios, “Rate 1” (65 % of soil cover), and “Rate 2” (100 % of cover), and “Control” soils without mulch. The biocrust development had a positive impact on soil aggregate stability and moisture retention before mulch application. However, one year after the mulch application the biocrust cover was drastically inhibited, especially at the highest rate of mulch. Independently of the biocrust presence, soils at Rate 1 registered a tendency to higher nitrogen content, available phosphorous, basal respiration, and microbial biomass carbon, suggesting an incipient recovery of soil conditions and soil functionality. However, the microbial community composition became more homogeneous and less diverse under the mulch presence (regardless of the application rate), and the positive effect of moss biocrust emergence on the microbial diversity was diluted after one year. The fungal community was particularly sensitive to the wood mulch presence, increasing in richness in response to fresh wood incorporation to soils, in particular saprotrophs and yeasts. The fungal and bacterial compositional shifts after the mulch application reveal an incipient wood decomposition stage, but the transitory loss in beta diversity after the moss biocrust suppression warns about the necessity of including the microbial diversity information into post-fire management planning. Studying the effects of forest management on the above and belowground soil communities is essential to understanding the resistance and resilience of semi-arid forests to the increasing intensity and severity of wildfires.