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The acidic soils of western Newfoundland require liming for successful production of most crops. Locally sourced paper mill waste wood ash (WA) and paper sludge (SL) have potential as cheaper alternatives to limestone (LIME). Two greenhouse experiments evaluated WA and SL as liming and soil conditioning amendments for annual ryegrass (Lolium multiflorum) production. At 55 days after seeding, soil pH in WA (6.2 and 6.3) and wood ash and paper sludge (WASL) (6.0 and 6.3) were not different from that in LIME (6.0 and 6.5) for Experiments 1 and 2, respectively. However, pH in SL was 0.4 and 0.3 points lower than in LIME. Compared to LIME, WA, SL, and WASL produced 31%–52% and 57%–74% greater biomass yield in Experiments 1 and 2, respectively. N uptake was greater in WA (60 and 129 kg N ha−1) and WASL (51 and 97 kg N ha−1) compared to LIME (40 and 85 kg N ha−1), in Experiments 1 and 2, respectively. SL did not differ from LIME in Experiment 1, but reduced N uptake by 57% in Experiment 2. The results show significant potential of WA as an alternative amendment for liming and yield improvement of annual ryegrass grown in NL podzolic soils. However, SL has limited potential due to the risk of increasing N immobilization and residual soil mineral N when growing conditions are limiting. Combining SL with WA or biochar seemed to alleviate these risks. Overall, the adoption of these amendments for field production systems warrants serious consideration, following supplemental field studies to determine optimal application rates and timing. Core Ideas: The podzolic soils of Newfoundland have low pH and fertility, hence require liming.Locally sourced wastes, such as paper mill wood ash (WA) and sludge (SL), could be used as liming and nutrient sources.WA was equivalent to limestone (LIME) in improving and sustaining optimal soil pH.WA produced 52% and 74% greater annual ryegrass yield than conventional LIME application in podzolic soils. [ABSTRACT FROM AUTHOR]

Land-use change in the boreal forest region leads to agriculture to be carried out on acid, shallow and low fertility soils. To correct soil fertility and promote crop productivity, manure and inorganic fertilizers are added, increasing the risk for greenhouse gas emissions (GHGE). To reduce the reliance on synthetic soil amendments while taking advantage of locally relevant industrial by-products, wood ash (WA) and paper sludge (SL) have been proposed as soil amendments for a range of soil types. We posited that amending soils with WA , SL and biochar will improve soil health parameters and fertility of boreal soils. Microbial activity resulting to nitrogen losses and availability were assessed. WA had a stronger ameliorative effect on acid boreal soils compared to SL. Both WA and SL increased soil microbial biomass and basal respiration resulting in higher net mineralization and thus significant increases in CO 2 emissions. Co-application of urea with WA or SL further increased net mineralization compared to when used independently. Conversely, the biochar's effect was short-lived and not significant. Nevertheless, addition of biochar was shown to reduce CO 2 emissions in all cases except in WA amended soils. No significant differences were observed in CH 4 emissions across all treatments. WA and SL may improve soil fertility and quality but could also contribute significantly to GHG emissions in acid boreal soils. Further research is recommended to assess the mitigating effect of various biochar feedstocks on GHG emissions when co-applied with WA and SL. • The effect of wood ash and paper sludge on acid soils was tested in incubation tests. • Both increased the soil microbial biomass, respiration, and net mineralization. • Greenhouse gas emissions were larger for paper sludge amended soils. • Supplementing biochar to wood ash increased soil CO 2 fluxes. • Supplementing biochar to paper sludge or limestone ash reduced soil CO 2 fluxes. [ABSTRACT FROM AUTHOR]

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 (C mic), activity and indices of microbial metabolism including C mic /C org ratio, metabolic quotient (qCO 2) 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 (C org) and some of its labile fractions, extractable C (C ext) and mineralizable C (C min), 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, C org , C ext , C min , N, C/N. Compared to land cover, aridity index had lower effect on investigated variables. In comparison to sites with higher C org content, sites with lower C org 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. [Display omitted] • Land cover is a key factor affecting soil health in areas at desertification risk. • Coniferous cover had the best effect on soil microbial, physical and chemical variables. • Croplands, grasslands, shrublands and broad-leaved soils differed at a lesser extent. • Soils poorer in organic C tended to lose C more rapidly than richer soils. • A minimum data set of soil health indicators was proposed. [ABSTRACT FROM AUTHOR]

Soil biochar is a kind of organic matter rich in carbon, which is of great significance in soil fertility improvement, fertilizer type innovation and greenhouse gas emission reduction. In this paper, Mg-modified biochar was prepared by thermal cracking using rice straw and corn straw as raw materials. The Mg-modified biochar and unmodified biochar were fully mixed with prepared soil samples at the addition amounts of 0.5% (w/w), 1% (w/w) and 2% (w/w), respectively, and then simulated indoor soil cultivation experiments were carried out. The effects of magnesium ion-modified biochar and non-modified biochar on soil chemical properties and the effects of different amounts of biochar on soil properties were studied. The results showed that the yield of Mg-modified biochar from rice straw and corn straw, prepared by pyrolysis, was 65%, and the ash content was large. The pH of MG-modified corn stalk biochar (MCBC) is weakly basic (8.55), while the pH of MG-modified rice stalk biochar (MRBC) is basic (10.1), and their internal structures are slightly different. After the application of biochar prepared from rice straw and maize stover, soil indicators were determined. Compared to the control, the chemical properties of the treated soil samples were significantly improved, with an increase in soil pH, an increase in the content of effective nutrients, such as fast-acting potassium, fast-acting phosphorus and alkaline dissolved nitrogen, and an increase in the content of the total phosphorus and total nitrogen, as well as an increase in the content of organic matter. The Mg-modified biochar was generally superior to the unmodified biochar in improving soil fertility, at the same addition level. It was also found that the rice-straw biochar performed better than the corn-stover biochar and had a more obvious effect on soil improvement in terms of fast-acting potassium, ammonium nitrogen, nitrate nitrogen, total phosphorus and total nitrogen contents. [ABSTRACT FROM AUTHOR]

Acid soils cover about 30% of the total ice-free land area. Based on this, the study aimed to evaluate soil acidity correction, focusing on identifying studies on limestone recommendations and corrective measures in agricultural systems. To do so, a systematic literature review (SLR) was carried out, composed of: 1) a systematic literature mapping (SLM), which identifies studies using topic-specific keywords and database automatic search; 2) Snowballing, technique that expands the initial selection using references of the selected studies; and 3) a SLR to synthesize the selected papers. First, 169 scientific papers were selected, of which 116 by SLM, 26 by backward Snowballing, and 27 by forward Snowballing. Most of the papers were about lime requirement (LR) methods (43%) and liming effects on soil and plants (19%). A total of 26 LR methods were found in the papers, of which most were base saturation and Shoemaker-McLean-Pratt methods. Calcium and magnesium carbonates, as well as dolomite, were the main sources of soil acidity correction. In brief, the study provided a critical and constructive analysis of the existing literature on soil acidity correction; the findings showed that liming is the most used and effective method to neutralize soil acidity. [ABSTRACT FROM AUTHOR]

Background and aims: The frequent occurrence of extreme rainfall events results in soils experiencing drying–rewetting (DRW) cycles. Such rewetting can lead to a surge in soil CO2 emissions; however, the main regulatory factors involved in this priming effect are unclear. Methods: In this study, we conducted a meta-analysis using data extracted from 43 published papers, to determine the direct regulatory factors involved in the priming effect of soil CO2. Results: The results indicated that the priming effect of rewetting on soil CO2 emissions was influenced by ecosystem type, soil properties, climatic factors, and the number of DRW cycles. The priming effect was the highest in cropland but the lowest in grassland when taking flux values observed before rewetting as the control group. It was also greater in acidic soils (pH < 6.5) and soils with a high clay fraction (clay ≥ 30%) than in other soils. The effect size (lnRR) of soil CO2 emissions was exponentially related to the mean annual precipitation (MAP), and decreased with increases in MAP. In DRW experiments, the priming effect of the first rewetting on soil CO2 emissions was the largest, an effect that gradually decreased with the number of DRW cycles, before disappearing completely. Most importantly, soil moisture influenced the peak time and the pulse time of the priming effect: the greater the change in soil moisture, the longer the peak time duration; the higher the maximum soil moisture content after rewetting, the longer the pulse time duration; and the lower the initial soil moisture content, the bigger the priming effect. Conclusion: Generally, physical mechanisms, especially soil moisture, directly regulate the CO2 priming effect during DRW cycles. Thus, this study provides a theoretical basis for assessing and predicting the impact of future precipitation changes on soil carbon cycling. Future studies should also carefully monitor any changes in soil microorganisms in response to changes in soil moisture during DRW cycles, because these appear to be significantly involved in CO2 release from soils. [ABSTRACT FROM AUTHOR]

Agriculture is the main economic activity of Mozambique and there is a lack of information about the quality of agricultural soils. In this paper, five soils from the Manica and Sussundenga districts (Manica province) sampled in the years 2021/2022 and 2022/2023 (before and after the rainy seasons) were subjected to an agronomical and environmental chemical analysis to assess their quality, from the fertility and environmental contamination points of view. Standard analytical methodologies from external certified laboratories and local X-ray fluorescence measurements were used. All the studied soils were acidic (pH ranging from 4.5 to 5.4), had no salinity problems (conductivity ranging from 4.2 to 11.8 mS/m), and had a low amount of soil organic matter (0.90% to 1.81%). Soils from the Sussundenga district had a very low cation exchange capacity (CEC) (average of 3.33 cmolc/kg), while that of those from the Manica district ranged from very low to average CEC (3.59 to 13.11 cmolc/kg). Sussundenga soils also had a phosphorous deficiency (values ranging from <20 to 38.5 mg/kg) and there were deficiencies and/or excesses of some macro and micronutrients in all soil samples. Manica soils were contaminated, apparently from geogenic origin, with Cr (280 to 1400 mg/kg), Co (80 mg/kg), Ni (78 to 680 mg/kg) and V (86 mg/kg). Agricultural soil monitoring must be fostered in Mozambique in order to improve food quality and quantity to ensure economic and environmental sustainability. [ABSTRACT FROM AUTHOR]

Research on the military-technogenic burden on the natural environment as a result of international conflicts is relevant since military operations cause catastrophic consequences for the environment and natural resources, which can lead to irreversible disturbances in ecosystems. The study is devoted to the examination of the impact of military-technogenic loads on the soils of military training grounds. The paper considers methods of soil sampling and their analysis for the content of heavy metals and other chemical compounds and determines the impact of this load on the ecosystem and possible consequences for human health. The influence of military activity on the soil quality of military training grounds, in particular in the Cherkasy region, is analysed. The study includes the determination by X-ray fluorescence and atomic emission method of the content of various elements in the soil. The results showed a substantial iron content, which may be due to the use of explosives in military exercises. It is noted that despite the fact that exceeding the norms of maximum permissible content concentration, no heavy metals were recorded in the examined soils, and the maximum lead content approached the maximum permissible concentration, which requires further monitoring and control of this parameter. Ph determination showed a slightly acidic soil condition in combat exercise sites, which can affect plant fertility and growth. The content of nitrogen, phosphorus, potassium, and boron was assessed, and the results showed a lack of these nutrients for normal plant development. It is established that soil damage as a result of military operations can have a long-term negative impact and pose a threat to residents and territories. The results of the tests indicate a slight technogenic load at the sites of military exercises. The detected contamination of the examined samples is insubstantial, which indicates that the impact of military activities on the soil condition is limited. The results of the study will help to understand the possible health risks for people living near military training grounds and respond appropriately to protect their health. [ABSTRACT FROM AUTHOR]

Volcanic tuffs rich in chabazite zeolites have been extensively examined for their potential to enhance soil properties and increase fertilizer efficiency, both in their natural state and when enriched with nitrogen (N). However, there is a scarcity of data regarding their utilization in acidic sandy soil, particularly when used alongside organic fertilizers. This paper presents the findings of a 50-day laboratory incubation study that investigated the dynamics of N pools in an acidic sandy-loam agricultural soil treated with various N sources. These sources included urea, N-enriched chabazite zeolite tuff, and pelleted composted manure applied at a rate of 170 kg N/ha. Additionally, the N sources were tested in combination with chabazite zeolite tuff mixed into the soil to assess its role as a soil conditioner. The results revealed distinct behaviours among the tested N sources, primarily impacting soil pH and N dynamics. Soil fertilized with manure exhibited slow N mineralization, whereas N-enriched zeolite displayed a more balanced behaviour concerning net NO3−-N production and NH4+-N consumption. Both N-enriched zeolite and urea temporarily altered the soil pH, resembling a "liming" effect, while pelleted manure facilitated a prolonged shift towards neutral pH values. Considering the water adsorption capacity of zeolite minerals, caution is advised when adjusting water content and employing combustion methods to measure soil organic matter in zeolite-treated soil to avoid potential inaccuracies. In summary, N-enriched chabazite zeolite tuff emerged as a valuable N source in acidic sandy-loam soil, offering a promising alternative to synthetic fertilizers and showcasing a sustainable means of N recycling. [ABSTRACT FROM AUTHOR]

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The aim of this paper is to justify the strategic priorities of financial provisions for sustainable soil management in agriculture of Ukraine. In conditions of limited financial resources, there is a need to identify the top priorities of sustainable soil management. The study found that the most important priority of financial support for sustainable soil management is to suspend the decrease of the content of humus and achieve its deficit-free balance (global priority - 0.556); the second position is occupied by the protection of soils from erosion (priority - 0.274); third place - enrichment of soils with nutrients substances (priority - 0.101); fourth place - amelioration of acid and solonets soils (priority - 0.069). In the context of identification of priorities of financial support for practical implementation of the proposed conception of sustainable soil management this paper also addresses the empirical expert evaluation of the relative importance (significance) of the principles of sustainable soil management, as well as the level of adherence (compliance) of these principles in agricultural enterprises of Ukraine. The obtained results demonstrate the state of compliance with the principles of sustainable soil management in agricultural enterprises, the availability of opportunities and reserves for improving the situation for their implementation, and as well due to which this should be carried out. Thus, 77.8 % of the principles were implemented at a low level, the rest (22.2 %) - at a very low level, so there are significant reserves to improve the situation. [ABSTRACT FROM AUTHOR]

The application of biochar (the by-product of biomass pyrolysis), as a soil amendment has been accepted as a sustainable solution to improve soil quality. The current study aims to establish a decision support tool for characterizing, ranking, and selecting biochars of different origins for soil improvement, thereby contributing to the development of a systematic approach, which lacks in the existing literature. The development of a Multi-Criteria Decision Support Approach applying a banded and weighted rating and scoring system allowed the selection and ranking of various biochars suitable for improving sandy soils before application. First, 14 selected, different biochar products (produced from industrial by-products, herbaceous, wood-based and manure-based feedstocks) were characterized with several physicochemical, biological and ecotoxicological methods taking into account both the technological and the environmental efficiency aspects of biochar utilization. Then, a system for the assessment and ranking of biochars for acidic, and calcareous neutral sandy soil improvement was developed, which could be flexibly adapted to different soil problems as well. Based on their performance in the tests, scores from (-5) to (+5) were assigned to each biochar. As a result, the grain husks and paper fiber sludge biochar was ranked as the most suitable for both acidic and neutral calcareous sandy soil improvement, with 55 and 43 scores, respectively (from the maximum 100). The applicability of this innovative multicriteria scoring-ranking system, as a tool for potential biochar users, was verified in microcosms and field-scale experiments, demonstrating the positive influence of this biochar on the acidic sandy soil. [ABSTRACT FROM AUTHOR]

This paper describes a wireless and battery‐free soil pH sensor made entirely of degradable materials. Soil pH monitoring is significant for precision agriculture and environmental conservation because soil health can be estimated by measuring soil pH. Soil pH can be measured by collecting soil samples and analyzing them in a laboratory environment or by inserting an electrode‐type sensor into the soil and measuring soil pH on site. However, neither method is suitable for wide‐area soil pH sensing for precision agriculture or environmental conservation. Herein, a fully biodegradable wireless pH sensor is presented that can be dispersed to outdoor environment to detect soil acidity. The sensor is operated wirelessly through split‐ring resonators (SRRs) that consist of patterned octacalcium phosphate (OCP)‐coated magnesium (Mg) on a poly‐lactic acid (PLA) sheet. At acidic soil pH, the degradation of each SRR results in a change in the electromagnetic response of the sensor. The operation of the sensor in six different types of acidic soils is demonstrated to distinguish the acidic soil wirelessly. It is expected that the biodegradable sensor can be applied to low‐cost, easy‐to‐use, and environmentally friendly monitoring of soil pH. [ABSTRACT FROM AUTHOR]

Purpose: High-silicon chromium iron (HSCI) has been used in ground grids in southern China, while there was a lack of study on its corrosion behavior in this soil environment. The purpose of this paper is to discover the corrosion of HSCI in acidic and alkaline soil solutions. Design/methodology/approach: The original defects on the HSCI surface were observed using optical microscopy, and the corrosion behavior of the HSCI in the acidic and alkaline soil solutions were jointly detected using electrochemical measurements and scanning electron microscopy/energy dispersive spectrometer. Findings: The results showed the corrosion rates of the HSCI in the acidic and alkaline soil solutions were limited, and the high contents of Cr and Si in matrix was responsible for its high corrosion resistance. The HSCI showed a similar corrosion tendency in the two solutions, while its corrosion rate in the acid soil solution was higher than that in the alkaline soil solution. The corrosion pits on the specimen surface were originated from the original defects in matrix, and the edges of the corrosion pits were more rounded than the original defects after 720 h immersion in the two solutions. The original defects in the HSCI matrix played a significant role in the corrosion process. Originality/value: The paper discovered the corrosion evolution of HSCI in the acidic and alkaline soil solutions. What is more, the acceleration role of the original defects on the corrosion of the HSCI in the acidic and alkaline soil solutions was discovered in the paper. The results are beneficial for the material selection of ground grid equipment in engineering. [ABSTRACT FROM AUTHOR]

The paper hereby focuses on the essential field of soil evolution in relation to the effect of long-term fertilization on plant yields and the essential, evolutionary, and impactful changes in their fertility. NP fertilization (by application of ammonium nitrate and concentrated superphosphate) causes a change in soil reaction over time through acidification with increasing N doses, while phosphorus is able to partially mitigate this process. Acidic soil—the typical preluvosol—as a result of adsorbed acidity activation, solubilizes Al ions and may become interested in calcic amendment. Acidification tendencies are also maintained in the amended variants, but to a lesser extent due to the neutralizing capacity of the amendment and the presence of calcium ions. Complex NP fertilization in acid soil (preluvosol) cultivated with wheat can maintain a relatively constant humus content (%), but calcium amendment can cause a reduction of this indicator. In contrast, under maize, due to the effects of conventional tillage and intensive tillage, fertilization contributes to a reduction in this indicator, which is more active against the background of limestone amendment. The phenomenon can be explained by potentiation through the mineralization of the organic component of the soil. This effect is diminished in alluvial mollisol with a higher humus content, saturated in bases, and a buffering capacity. Organic and organo-mineral fertilization can control the modeling of soil humus content and its agrochemical status. The regime of essential elements (N, P, and K) becomes active in mobile forms, and the precarious supply conditions of the initial stage tend to improve. Applied superphosphate evolves, differentiated from the applied dose and pH, into non-occluded mineral forms (P-Al, P-Fe, and P-Ca), which supply the mobile forms in the soil solution for the plants, with the importance of maintaining, more of these forms at the level required by plants. In the case of potassium, the dynamics of its forms in the soil (unchangeable and exchangeable) control the soil supply state of this element and the effect of its application to plants. The data presented show that long-term experiments can effectively support the study of soil fertility through the soil-plant relationship. [ABSTRACT FROM AUTHOR]

Biochar is important for soil improvement, fertilizer innovation, and greenhouse gas reduction. In this paper, Mg-modified biochar was prepared from rice and corn straw and mixed with soil at a 1% (w/w) addition in an indoor soil simulation experiment to study the effect of Mg-modified biochar on the chemical properties of acidic soil. The results showed that the addition of Mg-modified biochar reduced soil acidity and improved soil fertility. Compared with the control group, the Mg-modified biochar treatment significantly increased the concentrations of available potassium, available phosphorus, total phosphorus, organic carbon and exchangeable calcium and magnesium in the soil, and effectively increased the concentration of total nitrogen. Rice straw Mg-modified biochar treatment was more effective in increasing the soil-available potassium, available phosphorus, total phosphorus and exchangeable magnesium concentration, while corn straw Mg-modified biochar was more effective in increasing the soil organic carbon and exchangeable calcium concentration. In addition, the high pyrolysis temperature of Mg-modified biochar was more effective in promoting the soil-available potassium, available phosphorus and total nitrogen concentration, while the low pyrolysis temperature of Mg-modified biochar was more effective in promoting soil alkaline nitrogen, exchangeable calcium and magnesium. [ABSTRACT FROM AUTHOR]

Established international soil classification systems have not properly accommodated acid sulfate soils (ASS) and soil materials in Finland and Sweden because: (1) in these soils some diagnostic ASS properties are too deep to meet the depth requirements, and (2) there is a lack of defined diagnostic soil classification criteria for acidic and potentially acidic soil materials that do not completely fulfill the diagnostic pH-criterion of pH < 4.0. In this paper, two new ASS materials are introduced with the prefix "para" for parasulfuric material (oxidized material) and parahypersulfidic material (reduced material). These materials have diagnostic pH-criteria of pH 4.0-4.5 and 3.0-3.5 (field-pH for parasulfuric material and incubation-pH for parahypersulfidic material) for mineral and organic soil materials (here defined as > 20% organic matter; peat and gyttja), respectively. The term "para-acid sulfate soil (para-ASS) material" is introduced for soil materials which may have a considerable environmental impact due to mobilization of acidity and dissolved metals. Because organic acids may lower pH to values below the established pH-value of < 4.0 for ASS materials, a pH of < 3.0 is used in the Finnish-Swedish ASS classification for organic soil materials. These changes and new additions to existing diagnostic ASS materials have consequently also led to a slight modification of the required field-pH values of the existing terms "hypersulfidic material" and "sulfuric material". The Finnish-Swedish ASS classification further includes a systematic way for classification of the entire soil profile and no depth requirements for diagnostic ASS materials are present; what matters is the current or potential environmental impact that the soil has or may have. It is proposed that the Finnish-Swedish ASS classification may serve as a framework for establishing a unified ASS classification globally and that the new diagnostic ASS materials are included in relevant international soil classification systems. [ABSTRACT FROM AUTHOR]

Since the first issue of JSS in March 2001, the journal has developed into one of the largest (in terms of the number of papers published) and most respected (as indicated by its journal impact factor) journals in its subject area. The journal was established, in part, because of a recognition that soils and sediments had to date been treated as individual environmental compartments, and there was a lack of journals - and thus publications - that looked at the link between the two. 15 Li Y, Yu S, Strong J, Wang H. Are the biogeochemical cycles of carbon, nitrogen, sulfur, and phosphorus driven by the Fe-III-Fe-II redox wheel in dynamic redox environments? 27 Zhang Z, Solaiman ZM, Meney K, Murphy DV, Rengel Z. Biochars immobilize soil cadmium, but do not improve growth of emergent wetland species Juncus subsecundus in cadmium-contaminated soil. [Extracted from the article]

Perennial ryegrass (Lolium perenne L.) has potential in the phytoremediation of cadmium (Cd)-contaminated soil due to its strong Cd accumulation capacity and high biomass. In this study, we investigated the growth physiology, Cd accumulation, and metabolites of L. perenne roots under different soil acid stress levels (pH 4.0, 4.5, 5.0 and 6.0) and Cd concentrations (100 and 0 mg/kg) after 90 days of growth. The results showed that soil acid stress significantly impacts the remediation capability and physiological metabolic properties of L. perenne. Based on root Cd content and enrichment coefficient, soil pH between 4.5 and 5.0 was more conducive to Cd accumulation. The growth physiology and Cd accumulation of L. perenne were inhibited under high soil acid stress (pH 4.0). High soil acid stress caused a decrease in root length, root volume, and root biomass of L. perenne. Root malondialdehyde (MDA) content and the activity of antioxidant enzymes (catalase (CAT) and peroxidase (POD)) increased significantly in response to high soil acid stress to enhance tolerance. Metabolomics analysis revealed that acid stress resulted in significant changes in certain metabolites. Tartaric acid, fructose and amino acids (glutamate and lysine) in the roots of L. perenne were compatible solutes under acid stress. This study indicated that L. perenne has strong physiological and metabolic tolerance, as well as Cd accumulation ability, in response to soil acid stress. [ABSTRACT FROM AUTHOR]

This work aimed to evaluate the influence of soil characteristics and the applied amount of nicosulfuron on the degradation rate in soil. Soil samples were collected at three localities in Bosnia and Herzegovina -- Manjača, Kosjerovo and Tunjice. The experiment was carried out under controlled laboratory conditions. Plant protection product based on nicosulfuron (40 g a.s./L, OD) was applied in concentrations of 0.075, 0.15, and 0.30 mg a.s./kg of soil. Nicosulfuron residues were analysed by the modified QuEChERS method, followed by LC-MS/MS. Soils are classified as silty loams, with variations in mechanical composition and chemical properties. In slightly alkaline soil, the half-life (DT50) of nicosulfuron has increased (43.31 days) compared with DT50 (9.43-16.13 days) in acidic soils. The results indicate that soil characteristics and applied concentration significantly influence nicosulfuron persistence. Hence, it can be considered that nicosulfuron, applied to silty loam soils of Bosnia and Herzegovina, poses a low risk to subsequent crops and the environment. [ABSTRACT FROM AUTHOR]

Simple Summary: This paper focuses on the role of synergistic removal effects of earthworms and plants on two types of chromium-contaminated soils and their biological responses. We firstly examined the synergistic removal rate of chromium from contaminated acidic and alkaline soils via earthworms and plants, and then analyzed the speciation characteristics of chromium in soil after the experiment. Additionally, we also explored the accumulation of chromium in organisms and the earthworm intestinal bacterial community to reveal the biological responses. The main contribution of this study was to successfully prove that the combined use of Eisenia fetida and ryegrass had the best effect on removing chromium pollution from soil, and acidic soil exerted stronger pressure on earthworms which finally unbalanced the intestinal bacterial phyla. In future studies, we should consider not only the removal effect of heavy metals on soil via organisms, but also the stress effect on organisms themselves, and weigh up the advantages and disadvantages, which would be more conducive to the sustainable development of the ecological environment. Soil heavy metal pollution has become one of the major environmental issues of global concern and solving this problem is a major scientific and technological need for today's socio-economic development. Environmentally friendly bioremediation methods are currently the most commonly used for soil heavy metal pollution remediation. Via controlled experiments, the removal characteristics of chromium from contaminated soil were studied using earthworms (Eisenia fetida and Pheretima guillelmi) and plants (ryegrass and maize) at different chromium concentrations (15 mg/kg and 50 mg/kg) in acidic and alkaline soils. The effects of chromium contamination on biomass, chromium bioaccumulation, and earthworm gut microbial communities were also analyzed. The results showed that E. fetida had a relatively stronger ability to remove chromium from acidic and alkaline soil than P. guillelmi, and ryegrass had a significantly better ability to remove chromium from acidic and alkaline soil than maize. The combined use of E. fetida and ryegrass showed the best effect of removing chromium from contaminated soils, wih the highest removal rate (63.23%) in acidic soil at low Cr concentrations. After soil ingestion by earthworms, the content of stable chromium (residual and oxidizable forms) in the soil decreased significantly, while the content of active chromium (acid-extractable and reducible forms) increased significantly, thus promoting the enrichment of chromium in plants. The diversity in gut bacterial communities in earthworms decreased significantly following the ingestion of chromium-polluted soil, and their composition differences were significantly correlated with soil acidity and alkalinity. Bacillales, Chryseobacterium, and Citrobacter may have strong abilities to resist chromium and enhance chromium activity in acidic and alkaline soils. There was also a significant correlation between changes in enzyme activity in earthworms and their gut bacterial communities. The bacterial communities, including Pseudomonas and Verminephrobacter, were closely related to the bioavailability of chromium in soil and the degree of chromium stress in earthworms. This study provides insights into the differences in bioremediation for chromium-contaminated soils with different properties and its biological responses. [ABSTRACT FROM AUTHOR]

The effect of soil fixation and anti-scour instability of slope vegetation generally depends on the strength and anti-disintegration ability of slope soil due to increase of root system. Therefore, it is particularly necessary to study the disintegration characteristics of expansive soil related to slope instability under acidic conditions (simulated acid rain). In this paper, the response surface method (RSM) was used with the pH value, root diameter, root length, root coefficient, and distribution as independent variables, and the disintegration amount of root-soil (DARS) after 60min as the response value. Then X-ray diffractometer (XRD) was used to analyze the mineral composition changes of the sample under this environment. Simultaneously, the plasticity index of expansive soil at different values of pH was studied to discuss the disintegration mechanism of root compound expansive soil in an acid environments. The results show that the root system improves the anti-disintegration characteristics of the root-soil, and the effects of various factors on the amount of disintegration were as follows: root length > pH value > root distribution > root amount > root diameter. The DARS with a length of 20mm increased by 26.67% and 41.56% compared to the 30mm and 40mm. Compared to the horizontal distribution and horizontal + slant distribution, the DARS with slant distribution was increases by 11.39% and 20.24% respectively. The DARS with 2 roots is increased by 9.92% and 16.75% compared to 4 and 6 roots respectively. The 1mm diameter DARS is 6.65% and 15.49% higher than the 2mm and 3mm, respectively. In addition, an acidic environments can lead to an increase in the amount of disintegration or rate of disintegration. The disintegration at pH = 4.2 was increased by 11.4% and 22.4% compared to pH = 5.6 and pH = 7, respectively. The acidity affects soil disintegration is due to the hydrophilic minerals in the expansive soil react with H+ ion in the acid solution to form soluble salts. Due to the dissociation and leaching of free quartz and metal oxides in the soil to varying degrees, the ability of expansive soil to accumulate is reduced. The intensity of erosion and leaching decreases with increasing pH. In addition, the pH value can affects the plasticity index of the soil, which increases with the increasing pH, thus affects the disintegration properties of the expansive soil. [ABSTRACT FROM AUTHOR]

The phosphate precipitation of heavy metal induced by microorganisms plays an important role in immobilising heavy metal in soil. However, there is little knowledge about the effect of coexisting metal ions on the induction of Cu phosphate mineral and its stability. In this paper, the Cu phosphate precipitations, coexisting with Pb2+ or Ca2+ induced by strain LRP3, were characterised, and the stabilisation of the induced phosphate precipitates was also studied. The coexistence of Cu with Pb or Ca decreased the removal efficiency of Cu2+ by 17.18% and 9.78%, respectively, indicating the competitive adsorption between cations. Strain LRP3 could induce a new phosphate mineral of CuCa10(PO4)7 when coexisting with Ca and also generate the phosphate minerals of Pb(H2PO4)2 and Cu3(PO4)2 when coexisting with Pb. The Cu-Ca coprecipitate could enhance the stability of Cu in dilute acid solution and soil with or without a plant, whiles the Cu-Pb one showed the opposite effect. Also, the Cu-induced phosphate precipitates were relatively stable and not easy to be absorbed by Pakchoi (Brassica rapa var. chinensis). The results showed that the influence of coexisting metal ions should be considered when phosphate mineralisation technology is used to immobilise heavy metals in the environment. [ABSTRACT FROM AUTHOR]

The remediation of cadmium (Cd)–contaminated soil has gained much attention recently because Cd in soil threatens human health through the food chain. Although tremendous progress has been made in the remediation of Cd-contaminated soil in rice acid soil system, the mechanism and effects of Cd-contaminated soil remediation under these amendments in wheat weak alkaline soil are still limited. In this study, the remediation effect and related mechanism of Cd in weakly alkaline soil were carried out using zeolite, diatomite, and sodium bentonite as the main remediation components, supplemented by calcium dihydrogen phosphate and fulvic acid. The results of field experiments showed that the concentration of Cd reduced by 27.3 ~ 31.2% in rhizosphere soil and 34.3 ~ 54.2% in non-rhizosphere soil, and the maximum reduction rate of Cd concentration in wheat grain was 25.5%. The main factors affecting the concentration of Cd in wheat grains include the change in exchangeable Cd, the absorption capacity of wheat root, and the inhibitory effect on Cd transport from stem to grain in this paper. In general, this work provides a new potential management feasible pathway to alleviate the Cd toxicity of weakly alkaline soil and wheat grain. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to study the corrosion behavior of Q235 steel in the bentonite-based resistance-reducing agent (RRA) with different infiltration rates of underground water. Design/methodology/approach: The corrosion behavior of the steel in underground water was assessed by weight loss experiment, electrochemical impedance spectroscopy and polarization curve. Findings: The results showed that the corrosion rate of the steel in the RRA pastes was much lower than that in the original acidic soil. The underground water infiltration slightly accelerated the corrosion rate of the steel in the RRA pastes, but the acceleration role is weak. The bentonite-based RRA can be compatibly applied in the acidic soil. Originality/value: The bentonite-based RRA can significantly reduce the corrosion rate of the steel and is suitable to compatibly apply in the acidic soil. [ABSTRACT FROM AUTHOR]

In the current context of the increase in the amount of municipal solid waste as a result of the development of urbanization, in this paper we have analyzed the impact of the use of fly ash obtained from the incineration of municipal solid waste in agriculture on the development of plants as an improver of acidic soils due to the nutrients it contains. We presented ash treatment methods to reduce the content of heavy metals and salts. Based on the studies in the literature, it was found that by adding certain concentrations of fly ash to degraded soils, the quality, porosity, and texture of the soil are improved; the yield of certain crops increases; the water retention capacity of the soil and soil aeration are improved; the density of the soil bulk; the compactness of the soil is reduced; the pH value is optimized; the electrical conductivity of the soil is increased; the crust formation is reduced; and it provides micronutrients to the soil. In the context of the circular economy, by using fly ash as an organic fertilizer in agriculture, the amount of chemical fertilizers harmful to agricultural crops is reduced, the problem of ash storage is solved, and thus it no longer pollutes the environment. [ABSTRACT FROM AUTHOR]

This paper aims to assess the durability of one-part geopolymer (OPG) pastes exposed to acidic environments. Two different acids (HCl and H2SO4) with different pH values (pH of 2, 4, and 6) were used to simulate the acidic environment in the current study. Acid resistance of the OPG paste activated by sodium hydroxide [NaOH (NH)] and sodium metasilicate [ Na2SiO3 (NS)], respectively, was assessed in terms of pH variation, mass change, visual appearance, deterioration depth, and compressive strength loss for varied immersion periods (∼120 days). The scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDS) and mercury intrusion porosimetry (MIP) tests were employed to investigate the evolution of porosity, morphological change, and hydrate composition for the varied immersion times. The experimental results revealed that due to the formation of a dense structure, the NS-activated OPG paste had better resistance to the acid attack compared with the NH-activated paste. It was also found that the gypsum crystals formed in the sample immersed in H2SO4 solution could fill the open pores and adhere to the surface of the sample, which reduced the further acid attack to some extent. However, the expansion properties of gypsums would lead to a loss of mechanical performance at the later immersion period. Furthermore, higher porosity of the OPG paste developed as the pH value of the acid solution decreased, thereby inducing the loss of mass and compressive strength and the increase of deterioration depth. Finally, as the immersion age and acid concentration increased, decalcification in the sample tended to occur, which caused a greater loss of compressive strength and a higher porosity. The outcome of this study could provide guidance for the application of the novel material in acid soil layer improvements or acid-resistant geotechnical structures. [ABSTRACT FROM AUTHOR]

Liming is one of the key agronomic practices to improve crop yields in acid soils because, among other things, it reduces aluminum toxicity and creates favorable conditions for crop growth. For an effective liming program, the methods to determine lime requirement should be as precise as possible. This paper reviews the existing lime requirement methods and discusses the potential of a new one suitable for routine use in the laboratory to test most agricultural soils. The most widely used lime requirement methods can be categorized into four groups: titration, incubation, buffer, and field methods. Other methods such as spectroscopy method or the use of empirical equations have also been adopted. Although some methods are highly reliable, they are not optimal for routine use because they are inconvenient during the laboratory procedures or cannot be validated for all conditions. Based on the linearity between soil pH and the added base in the pH range from 4.5–6.5 in most agricultural soils, a titration‐based method on 1:1 soil:0.01 M CaCl2 slurry of a single sample appears to be a promising candidate for routine use. In further studies, this generally applicable method should be evaluated to provide a better comparison to established methods for lime requirement determination. [ABSTRACT FROM AUTHOR]

Microscopic remains of plants, hairs, blood, bone, and sinew have been detected on Stone Age implements as evidence of the ways the tools were used. Together with use-wear analysis, microresidues enable us to obtain additional information of artefact biographies. However, the preservation of residues is not a straightforward issue. Although bones, plant matter, and wood have a tendency to decompose rapidly in acidic podzol soils, the acidity favours the preservation of keratinous tissues such as hairs and feathers. Because the analysis of microresidues has not been applied on Finnish quartz artefacts, this paper presents a preliminary testing of the method in a Late Stone Age settlement site in Kraakanmäki 3, western Finland. As a result, we found microscopic remains of hairs, feathers, and plants, which enable us to speak for the careful handling of quartz and stone tools at the excavations for further analyses. [ABSTRACT FROM AUTHOR]

Ultisols are acidic soils found in humid climates and are known for poor fertility. Crude oil impacted ultisols, therefore, require special treatment measures to account for nutrient loss during treatment. In this paper, we report the utilization of a food waste, aqueous extracts of waterleaf (Talinum triangulare), as a plant-derived surfactant to wash simulated crude oil-contaminated soils. The soils before and after washing were monitored for microbial loads, nutrient parameters, physicochemical characteristics, total petroleum hydrocarbons (TPHs) and polycyclic aromatic hydrocarbons (PAHs). Although higher amounts of PAHs (up to 100%) were removed compared to TPHs (up to 95.7%), the results revealed that the efficiency of the waterleaf extracts was comparable to that of a commercial surfactant sodium dodecyl sulphate. However, soils washed with the waterleaf extracts retained some significant amounts of nutrients and favourable pH moderation. In both surfactants, soil microbial loads reduced significantly. Overall, the aqueous waterleaf extracts showed potential as ecofriendly surfactants and nutrients retainer during soil washing of contaminated ultisols. [ABSTRACT FROM AUTHOR]

Selenium is an important element for human health. Many studies have identified selenium deficiency in soil and water as an important factor in causing Keshan Disease (KD) in Northeast China. Previous studies have mainly focused on soil selenium content, staple food selenium content, and human selenium level, but there are few systematic studies on soil selenium's existing forms and their migration from soil to crops and the human body. This paper focused on inferring the barrier factors in the migration of selenium from soil to crop and the human body and transformation of its compounds. It provides a reference basis for the etiological analysis, prevention, control, and elimination of KD. The study used 121 183 samples of topsoil (0−20 cm), 30 295 soil parent samples of selenium and other geochemical indices in northeast China, and crop seeds and human hair samples from the KD endemic area. The surface soil selenium was dominantly selenium-sufficient in Northeast China. However, the soil selenium levels were generally low. The average topsoil selenium in Northeast China was 0.20 mg/kg, significantly lower than the world's average soil selenium content (0.4 mg/kg) and slightly lower than the Chinese average soil selenium content (0.24 mg/kg). Soil selenium mainly existed in strongly bounding by organic bound, with humic acid, and residue forms. The amount of selenium available to plants was sufficient in the selenium-sufficient and KD-endemic areas. However, the average selenium content of human hair was deficient, on average, with 0.16 mg/kg in KD endemic area. We assume that lower soil selenium content may be the basic factor influencing the biogeochemical deficiency of selenium in Northeast China. The sequestration of selenium by clay chemical constituents, such as iron and aluminum oxides and soil organic matter, especially in acidic soils, is another direct contributing factor to the low selenium content in biogeochemical food chain, which increases the risk of KD in the population. [ABSTRACT FROM AUTHOR]

Aggregates are the basic structural units of soil; therefore, understanding the distribution and speciation of heavy metals (HMs) in soil aggregates is crucial for the clarification of the environmental behaviour of HMs. In this paper, seven soil profiles from different climatic type regions were sampled and grouped into six size aggregates (>2, 2–1, 1–0.6, 0.6–0.25, 0.25–0.053, <0.053 mm) to determine the distribution and chemical speciation of Cd, Cu, Mn and Pb. The results showed that the vertical distribution of Cd, Cu, Mn and Pb was differed, and the content of total Cd and Pb was ranked in the same order at both subsoil and parent material layer. Although the proportion of <0.053 mm size aggregate was lowest in bulk soil, fine particles showed higher content of total HMs and higher per cent of labile form distribution. However, the contents of total HMs were not always positively correlated with the content of acid soluble or potentially labile fractions of HMs. Total contents of Cu and Mn in aggregates from acidic soils were high, but these two HMs only posed light ecological risk according to the risk assessment code values. Soil organic matter (SOM) and soil pH were involved in the speciation of HMs. Acid exchangeable fraction of Mn in aggregates showed a decreasing trend from alkaline to acidic soils, and SOM positively correlated with the content of oxidisable fraction. For Cd, Cu and Pb, the content of potentially labile fraction of Cu positively associated with the content of Pb potentially labile fraction, and the content of residual fraction of Cd were negatively correlated with the content of Cu residual fraction. [ABSTRACT FROM AUTHOR]

: Despite the determination of zinc (Zn) isotope in soil being undertaken by several laboratories worldwide, sample preparation steps are varied due to diverse soil properties and compositions. This paper proposes a widely applicable soil acid digestion procedure that has been thoroughly evaluated for both soil and geological reference materials. To ensure the general applicability of this method to large varieties of soil samples, synthetic multi‐element solutions of high matrix element: Zn ratios (M/Zn) were prepared by embracing all possible elemental compositions of forty‐three certified reference materials; the chemical preparation procedure was then tested and optimised using these synthetic solutions. Results show that the recovery rate of Zn could reach 99–100% after the pre‐treatment. Based on this method, the δ66/64Zn data relative to JMC‐Lyon 3‐0749L Zn of previously uncharacterised NIST reference materials (including SRM 2709a San Joaquin soil, SRM 2710a Montana Soil and SRM 2711 Montana Soil) and Chinese certified reference materials (GSS‐1a, GSS‐7a, GSS‐5, GSS‐8, GSS‐14, GSS‐18, GSS‐20, GSS‐24, GSS‐31) were measured using MC‐ICP‐MS with a range from ‐0.08‰ to 0.35‰. The Zn isotope compositions of twenty‐nine soil samples from twenty‐one provinces/municipalities across China were also analysed and were found to fall within typical ranges from ‐0.09‰ to 0.28‰. The intermediate precision of several pure Zn standard solutions was better than ± 0.05‰ (2s) over 22 months of measurement. This method and results are useful for comparison and calibration of data between laboratories as well as providing a solid reference soil dataset for future studies dealing with Zn isotopes. [ABSTRACT FROM AUTHOR]

In boreal forests in Canada, broadleaf stands are characterized by generally well-drained soils and a humus-rich layer. In contrast, spruce-moss stands are often characterized by more poorly drained soils and acidic humus layer. However, presence of these two forest types in various degrees of mixture in stands can be beneficial to spruce seedlings productivity. It was hypothesized that leaf litter and humus from pure spruces-moss stands, pure broadleaf stands, and mixed stand may influence Black spruce (Picea mariana (Mill.) BSP) seedling growth and development differently. A greenhouse experiment was carried out to evaluate the effect of different leaf litter and different humus on spruces seedlings. Our results suggest better development for seedlings grown in humus from mixed stands and pure broadleaf stands compared to humus from pure B. spruce or standard forest nursery substrate. Furthermore, leaf litter from broadleaf trees species, such as species Speckle alder (Alnus rugosa (Du Roi) R.T. Clausen), T. aspen (Populus tremuloides Michx), Willows (Salix spp.) and Paper birch (Betula papyrifera Marsh.), has shown distinct results in the growth and development of B. spruce seedlings in greenhouse. Furthermore, promotion of mixed stand can increase B. spruce productivity by improving the physicochemical composition of the forest floor. [ABSTRACT FROM AUTHOR]

In order to solve the problem of solid waste soda residue (SR) environmental pollution and resourceful utilization, lime soil modified by high content soda residue (LSMHCSR) is prepared by solid waste SR, lime and soil. In this paper, the basic characteristics of SR and the mechanical properties of LSMHCSR were tested, and the enhancement mechanism of LSMHCSR was analyzed. The test results showed that: (1) SR is mainly composed of CaCO3, Ca(OH)2 and CaCl2, with high natural moisture content, which is not recommended as a separate engineering filler; (2) As the SR content gradually increased, the optimum moisture content of LSMHCSR gradually increased, with the maximum dry density first increasing and then decreasing; (3) With SR content in the range of 10% to 30%, both 7d and 28d UCS of LSMHCSR increased first and then decreased, reaching the maximum under 15% SR, with the increase as high as 36.9% and 37.2%, respectively. The optimal material mix ratio was SR:lime:soil = 15%:6%:85%; (4) An appropriate amount of SR could effectively promote the physical filling, cementation, crystallization and carbonization, and pozzolanic reactions of the material, and the resulting cementing substances, such as CaCO3 crystals, C-H-S and N-A-S-H, could improve the material strength. However, under excessive SR amounts, the excess SR did not react, with the material strength reduced. Based on the engineering benefit analysis of the test section, lime soil modified by high content SR can effectively alleviate the road material supply shortage, soil erosion and solid waste pollution problems, demonstrating remarkable technical, economic and social benefits and enjoying a good prospect of application and promotion. [ABSTRACT FROM AUTHOR]

Soil acidification is a natural phenomenon that human activity can accelerate or manage. Acid soils limit plant growth by reducing nutrient availability and causing aluminum toxicity, significantly reducing crop production. Liming has proven efficient for increasing crop yield on acidic soils. Knowledge is required on the effect of liming on the soil pH dynamics to find the suitable material, application rate, timing, and method. The objective of this study was to develop a prediction model of soil pH temporal variations after lime application using data from the literature. A database was built from research results extracted from 16 scientific papers that provided data on soil acidity changes over time under different liming treatments. Machine learning (ML) was used to predict soil pH dynamics from eight predictive parameters: rate of application, time since application, neutralizing value (CCE), grind fineness (D50), pH measurement depth, soil acidity (pH prior to liming), the type of solution used for pH measurement (water or CaCl 2) and the soil:solution ratio used to measure pH. Since soil pH fluctuates with seasons, all pH values were expressed as difference between the actual pH value and that of an unlimed control (ΔpH). The Random Forest (RF) algorithm was tested to predict ΔpH over time. On testing, we obtained an R2 between measured and predicted ΔpH values of 0.881 and an RMSE of 0.230. These results are excellent, considering the heterogeneity in soils, liming materials, and pedoclimatic conditions found in the 16 papers. The primary factors influencing ΔpH, ranked by their impact are application rate, time elapsed post-application, and lime characteristics including its grind fineness and neutralizing value. • Random Forest robustly predicts soil pH change over time following lime application. • The predictors are: rate, neutralizing value, particle size, depth, and initial pH. • The model predicts that, on average, lime increases soil pH for 82 weeks. • Machine learning models are promising tools in managing liming practices. [ABSTRACT FROM AUTHOR]

This paper is aimed to evaluate the behaviour of 25 winter barley genotypes, tested on the acid soils at ARDS Livada, during the 2016-2018 period, in two ways of sowing: one at a distance of 12.5 cm between the rows and the other one at the distance of 25cm. The variance analysis led to the fact that the sowing distance (D), as a variation source, does not significantly influence the yield. On the other hand, the variety (S) and the interaction of distance and years between the barley varieties, had a significant influence on the yield. The regression analysis and the variation coefficient led to the identification of the most productive, stable and adaptable genotypes, specific to this area (Ametist, Cardinal, Artemis, Smarald). The larger sowing distance positively influenced the thousand grain weight, the hectolitre mass and the number and weight of the barley grains/ears. The attacks of the pathogen agents have been reduced (with 3-6%) and the resistance to lodging has been increased (with over 30%). [ABSTRACT FROM AUTHOR]

Methods used to compare the effectiveness of liming materials (e.g., relative neutralizing value, RNV; effective calcium carbonate equivalent, ECCE) were developed for ground limestone. This method is relatively untested on industrial byproducts that could be used when limestone is expensive or unavailable. The objective was to determine if RNV applies to both ground limestones and industrial byproducts. A 42-d incubation study was performed on three acid soils with 11 ground limestones and 9 different byproducts at four rates based on titration and the modified Adams-Evans buffer method. Overall effectiveness, assessed as RNV compared to Ca(OH)2, averaged 101.5 ± 0.9% for all the evaluated liming materials, except the paper sludge and dolomitic marble. Thus, RNV was a good estimate of neutralizing ability when particle size was accurate. Addition of RNV to packaging would facilitate the commercial use of byproducts as liming materials allowing consumers to compare products by price and properties. [ABSTRACT FROM AUTHOR]

This paper is intended to probe into the mechanism and environmental effects of modified chitosan, a kind of new materials, on heavy-metal contaminated soil under acid rain condition. Thereby, a leaching experiment of soil-column with simulated acid-rain trickling was conducted, leachate being collected from the soil-column, and ephehydrin modified chitosan-biochar composite (ECS-B) and protochitosan were used as stabilizers. The parameters of pH, conductivity and heavy metals (Cu, Pb, Zn and CD) of the leachate were analyzed in terms of contents and morphological change, and an accumulation-release model of heavy metals under leaching condition were put forward. The results of the experiment showed that compared with the control group, the pH value of leachae increased by 1.32 when ECS-B stabilizer had been added. EC changed significantly, rising up to 1.75 times of that of the control group; compared with the control group, the accumulative contents of Cu, Pb, Zn and Cd were decreased by 82.35%, 71.47%, 61.88% and 90.44%, respectively; and after leaching, the residual state of each heavy metal was 2.59 times higher than that of the control group. As to the study on the release of heavy metals from soil, it was considered involving a complex reaction process controlled by a variety of diffusion mechanisms. Besides, ECS-B stabilizer can inhibit the acid-rain leaching of heavy metals in soil by the increase of soil base ions, and the actions of surface complexation, precipitation and ion exchange, thus effectively reducing the ecological environment risk. [ABSTRACT FROM AUTHOR]

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The paper aimed at evaluating the effects of biochar (BC) produced by slow pyrolysis of vine pruning residue on soil physicochemical properties and tomato plant growth. A greenhouse experiment was conducted for 66 days, applying different treatments for 3 soil types, i.e., foliar fertilizer, BC (at a volumetric ratio between BC and soil of 20/80), BC + foliar fertilizer, and no treatments. Strongly alkaline BC (pH = 9.89 ± 0.01) had a significant beneficial effect on the growth performance of tomato plants sown in a strongly acidic soil (pH = 5.40 ± 0.02). The mean values of height, number of leaves, and collar diameter of plants grown in BC-amended soil without foliar treatment were up to 50% higher than those of plants grown in soil with the other treatments. This positive effect of BC on plant growth is due to the changes in the soil properties. The addition of BC led to increased values of electrical conductivity, pH, soluble and available nutrient concentration. Moreover, BC reduced soil bulk density by about 50%, resulting in improved plant root development and thus enhanced water and nutrient uptake. Accordingly, BC derived from vine pruning residues can improve soil quality and tomato plant growth, as well as reduce biomass residues. [ABSTRACT FROM AUTHOR]

Nitrification inhibitor (NI) is often claimed to be efficient in mitigating nitrogen (N) losses from agricultural production systems by slowing down nitrification. Increasing evidence suggests that ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) have the genetic potential to produce nitrous oxide (N2O) and perform the first step of nitrification, but their contribution to N2O and nitrification remains unclear. Furthermore, both AOA and AOB are probably targets for NIs, but a quantitative synthesis is lacking to identify the "indicator microbe" as the best predictor of NI efficiency under different environmental conditions. In this present study, a meta-analysis to assess the response characteristics of AOB and AOA to NI application was conducted and the relationship between NI efficiency and the AOA and AOB amoA genes response under different conditions was evaluated. The dataset consisted of 48 papers (214 observations). This study showed that NIs on average reduced 58.1% of N2O emissions and increased 71.4% of soil NHC4 concentrations, respectively. When 3, 4-dimethylpyrazole phosphate (DMPP) was applied with both organic and inorganic fertilizers in alkaline medium soils, it had higher efficacy of decreasing N2O emissions than in acidic soils. The abundance of AOB amoA genes was dramatically reduced by about 50% with NI application in most soil types. Decrease in N2O emissions with NI addition was significantly correlated with AOB changes (R² = 0.135, n = 110, P < 0.01) rather than changes in AOA, and there was an obvious correlation between the changes in NHC4 concentration and AOB amoA gene abundance after NI application (R² = 0.037, n = 136, P = 0.014). The results indicated the principal role of AOB in nitrification, furthermore, AOB would be the best predictor of NI efficiency. [ABSTRACT FROM AUTHOR]

In the present study, eight rhizobial strains (RH-1 to RH- 8) were isolated from root nodules of cowpea which grows in acidic soils of Wayanad. They were characterized based on morphological, physiological, biochemical and molecular characteristics. The results on plant growth promoting traits showed all isolates positive to IAA production, four positive to ammonia production and five positive for in vitro siderophore production. Three isolates exhibited antagonistic activity and none of them showed volatile cyanogen production. The 16S rRNA gene sequence analysis revealed all the isolates to show similarity to Rhizobium sp. While rhizobia generally have a pH range of 6.5-7.5 for optimum growth, the isolates RH-1. RH-2, RH-4 and RH-8 grew in a liquid yeast extract - mannitol agar medium at pH-4, suggesting acid tolerance in the strain of Rhizobium. The isolates were authenticated for their nodulation and growth promotion of cowpea in a paper cup experiment and four isolates (RH-2, RH-3, RH-4 and RH-5) were evaluated for their growth promotion in cowpea under field condition. It was observed that inoculation of Rhizobium increased nodulation, growth parameters and yield of cowpea compared to uninoculated control. This study showed that these rhizobial isolates with plant growth promoting traits can be used to promote the growth and yield of cow peain acidic soils of Kerala. [ABSTRACT FROM AUTHOR]