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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 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]

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]

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]

Abstract: This study was conducted under greenhouse conditions to evaluate the potential use of SPS as a fertilizer, amendment and/or liming agent for wheat (Triticum aestivum L.). Two representative Mediterranean agricultural soils, a Cambic Arenosol (cmAR) and a Cromic Cambisol (crCM) were used. Treatments included four sludge rates ranging from 0 to 40gkg−1 (equivalent of 0, 38, 88 and 120Mgha−1). A significant increment in soil pH, organic carbon, N total, available P and exchangeable K were observed in both soils. Sludge application significantly increased N and decreased Zn, Mn and Cu concentrations in wheat. Wheat grain yields were reduced by 33% and 37% when 120MgSPSha−1 was applied to cmAR and crCM soils, respectively, due apparently to unavailability of Mg. However, straw yields, with much lower Mg requirements, increased significantly with SPS rates. Secondary pulp mill sludge seems to be a potential source of organic matter, N, P, K and a potential soil amendment liming agent for acid soils, when appropriate supplemental fertilizer was provided. For grain crops grown in these soils, addition of Mg is required for proper nutrient balance. [Copyright &y& Elsevier]

Abstract: In the last few years solidification/stabilisation of acidic soils polluted by heavy metals with low-cost sorbents has been investigated. Paper mill sludges are produced in large amounts and their disposal is a serious environmental problem. The possibility was therefore studied of using paper mill sludge as a stabilizer to reduce the bioavailable metal forms in polluted soils and thus the transferability of metals to plants (barley). We first investigated the sorbing properties of paper mill sludge for Zn(II) and Pb(II) and then their fractionation both in a polluted soil and in the same soil amended with paper mill sludge in order to check the decrease in mobile forms. Finally in both soils we tested the uptake of two metals by common barley in order to assess the performance of soil remediation from an ecological point of view. The addition of paper mill sludge to a soil contaminated by lead and zinc induces a decrease in the mobile forms of both metals, probably due to the presence in sludge of organic matter and kaolinite, which are able to bind the metals very strongly. The decrease in the mobile forms, which are the most readily available for uptake by plants, corresponds to a decrease in plant uptake. [Copyright &y& Elsevier]

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]

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]

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]

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]

Acid sulfate soils (ASS) are rich in Fe, low in available P, and low in soil pH. In acid soils, low P availability is associated with high Fe concentration, which has a high capability in P retention. The reactivity of Fe oxyhydroxides turns large proportions of soil P into insoluble or unavailable form. This review paper is addressed to provide new insights into the Fe and P relationship as the P source for rice (Oryza sativa L.) in ASS. Fertilizer application did not significantly alter P solubility in soil solution due to high reactivity and retention power of Fe mineral in ASS, but rice cultivation practice such as water management and soil amelioration has influenced formation, crystallization and character of Fe mineral. Subsequently determining adsorption and desorption of P. Soil waterlogging and drying alternately during rice cultivation have change soil pH and redox potential (Eh), causing dissolution of P from vivianite and reduction of Fe(III)-P to Fe(II)-P. We summarize that Fe-P pools (amorphous-Fe-P) in the rice fields in ASS are categorized as readily available or labile P fraction. [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]

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]

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]

In the course of highway construction and use in loess area, subgrade settlement disease is common and has great destructiveness. The cone penetration test (CPT), especially the pore pressure cone penetration test, can provide three continuous readings along the exploration depth cone tip resistance, lateral friction resistance and excess pore water pressure. In this paper, CPT tests are carried out in the losses areas in Shanxi, China. Some data and curves are obtained by using CPT, which are quite different from those obtained by conventional drilling, reflecting the soil layer characteristics of the subgrade section, in order to provide a reference for similar projects. The results showed that CPT has a strong advantage in the analysis of the effect of compacted pile in the treatment of pile length and the improvement and reduction of indicators of different layers along the depth direction. However, the correlation between the static penetration and the compaction coefficient commonly used in the current norms still needs to be further studied to enhance the correlation analysis with detection parameters. [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]

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]

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]

Aluminum toxicity in acidic soil has become one of the main factors limiting crop growth and yield. Rapeseed is an important oil crop in China, which is mainly planted in the provinces and regions of the Yangtze River Basin where soil acidification is more serious. Rapeseed is one of the crops sensitive to aluminum toxicity, but the mechanisms of aluminum tolerance are still poorly understood. This paper reviewed the production of aluminum toxicity, the effect of aluminum toxicity on crop growth, the mechanism of crop aluminum tolerance, and the research progress on aluminum tolerance of rapeseed, and provide reference for the cultivation of new varieties of aluminum tolerant and high yielding rapeseed. [ABSTRACT FROM AUTHOR]

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]

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]

The use of peracetic acid (PAA) in advanced oxidation processes has gained significant attention recently, but the knowledge of activating PAA to degrade polycyclic aromatic hydrocarbons (PAHs) is limited due to the variety and selectivity of reactive substances in PAA oxidation system. This paper presented the first systemically study on the degradation of PAHs by PAA activation in soil. It was found that heat-activated peracetic acid (heat/PAA) was capable of degrading phenanthrene (PHE) efficiently with degradation efficiency > 90 % within 30 min. Experimental results demonstrated that a series of reactive oxygen species (ROS) including organic radicals (RO•), hydroxyl radicals (HO•) and singlet oxygen (1O 2) were generated, while acetylperoxyl (CH 3 C(O)OO•) and acetyloxyl (CH 3 C(O)O•) radicals were primarily responsible for PHE degradation in soil. Further analysis shows that polymerization products such as diphenic acid, 2′-formyl-2-biphenylcarboxylic acid and other macromolecules were dominant products of PHE degradation, suggesting polymerization driving PHE degradation instead of the conventional mineralization process. Toxicity analysis shows that most of the polymerization products had less toxicity than that of PHE. These results indicate that PAA activation was a highly effective remediation method for PAHs contaminated soil, which also provided a novel mechanism for pollutant degradation with the PAA activation process for environmental remediation. [Display omitted] • The degradation of PAHs in soil by heat-activated peracetic acid was systematically studied. • Heat-activated peracetic acid was capable of degrading phenanthrene efficiently within 30 min. • CH 3 C(O)OO• and CH 3 C(O)O• were primarily responsible for phenanthrene degradation in soil. • Polymerization products and other macromolecules were dominant products of phenanthrene degradation. [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 presents a possible modality of improving the fertility of acid soil by treating it with alkaline compounds, containing essential and trace elements, resulted in the industrial process of manufacturing magnesium carbonate and oxide from dolomites. The two mineral sources have resulted from the magnesium products industry and contain in their composition significant contents of magnesium and calcium as well as low contents of trace elements such as iron, copper, manganese and zinc. The difference between the two waste types lies in the double magnesium content, established for the crusts deposits. Because of their alkaline reaction and nutritive elements content, the two waste types can be revaluated in agriculture as amendment on acid soils. The experiment pursueds the effects of soil treatment with 2 waste types applied in different doses.The obtained results show a buffer effect on the acid soil reaction and an increase of the essential and trace elements content of the treated soil. The pH buffering process and the enrichment of essential and trace elements in soil by alkaline waste supplies establishes in soil the enhancement of global soil fertility. The paper shows the effects of soil treatment with four different doses of industrial waste concerning the soil reaction and calcium- magnesium content. The obtained results indicate that soil reaction turns from acid to neutral, while the established increase for calcium soil content reached 51% and 26% for magnesium content, both generated by the highest experimented waste dose. The originality of this paper consists in the utilization of these waste, resulted from the magnesium products industry in agriculture as soil amendment. The importance of this study lies in the fact that, on the basis of the obtained results, a new amendment technology can be conceived by specifying the suitable dose of waste, usage manner and application frequency. [ABSTRACT FROM AUTHOR]

To explore the differences and change rules of soil nutrients and enzyme activities in Larix gmelinii forest in the cold temperate zone, so as to provide scientific basis and data basis for in-depth understanding of forest ecosystem functions and future development trends in the cold temperate forest ecotone in China. In this paper, four different types of larch forest (Betula platyphylla -Larix gmelinii, Rhododendron dauricum-Larix gmelinii, Larix gmelinii, and Larix gmelinii plantation) in Heilongjiang Zhongyangzhan Black-Billed Capercaillie Nature Reserve were selected as the research objects. Sampling was carried out by season, and the soil. chemical properties and enzyme activities ( catalase, acid phosphatase, urease, sucrase and cellulase) were determined in different seasons, and the dynamic changes with seasons were also explored. Results showed that: (1) Soil chemical properties and enzyme activities were significantly different in different forest types and seasons, and the changing trends were also different to some extent. (2)Soil acid phosphatase was significantly affected by the contents of soil total P, total N and available K. Soil catalase was significantly positively correlated with the contents of total N, available N, available K and available P. Soil sucrase was mainly affected by the contents of available P and available N. Soil urease and cellulase were most affected by soil organic carbon content. (3)The principal component analysis showed that there were significant differences in soil enzyme activities and soil chemical properties among the four forest types, and first principal component 1 could explain more than 50% of the variance variables. The soil chemical properties and enzyme activities in different Larix gmelinii were significantly different with the seasons, which were related to the accumulation of litter and the difference of vegetation types. Soil enzyme activities were correlated with soil chemical properties to varying degrees. [ABSTRACT FROM AUTHOR]

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]

Aluminium (Al) toxicity is a major limiting factor of crop production in acidic soils. The objective of the current study was to evaluate the development of lucerne (Medicago sativa L.) cultivars and their response to mobile Al toxicity. Three screening methods: filter paper-based, hydroponic and soil-based, were used to assess 13 M. sativa cultivars for their tolerance of mobile Al. Major biological indicators used to analyse mobile Al tolerance were hypocotyl length, root length and root and hypocotyl tolerance index. Toxic effects of mobile Al manifested themselves on all the biological indicators tested, which was shown by the correlations between the biological indicators and screening methods. Under filter paper-based method, the root and hypocotyl tolerance index ranged from 0.0% to 23.2% and from 0.0% to 37.2%, respectively at 16 mM AlCl3 (aluminium chloride). Greater differences in M. sativa cultivars' tolerance to mobile Al toxicity were identified between the hydroponic and soil-based methods. In the hydroponic method, the root and hypocotyl tolerance index ranged from 41.0% to 78.2% and from 62.1% to 90.2%, respectively at 50 µM AlCl3. Under the soil-based method, hypocotyls were more damaged by Al toxicity compared with roots at soil pH 4.5 and 4.3. The root and hypocotyl tolerance index at pH 4.5 was 73.5% and 39.3%, at pH 4.3 - 35.6% and 26.3%, respectively. The cultivars 'Mriia odes'ka', 'Romagnola', 'Kunsmme' and 'Juurlu' were distinguished by the highest root and hypocotyl tolerance index under hydroponic and soil-based methods. 'Žydrūnė', 'Birutė', 'Magnat', 'Viktoria' and 'Magda' were distinguished by root and hypocotyl tolerance index under hydroponic method. The root tolerance index of these cultivars was the highest under filter paper-based method. These cultivars are considered as tolerant accessions and may be used as donors in breeding for Al toxicity tolerance. [ABSTRACT FROM AUTHOR]

The aim of the paper is to give an overview on the chemistry of soil organic carbon (SOC) affecting nutrient availability, the emission of greenhouse gases and detoxifying harmful substances in soil. Humic substances represent the stable part of SOC, accounting for between 50 and more than 80% of organically bound carbon in soil. Humic substances strongly affect the soil solution concentration of several plant nutrients and may increase P-, Fe-, and Cu- solubility, thereby increasing their plant availability. Soil organic carbon, mainly humic substances, can detoxify monomeric Al in acid soils, can strongly bind toxic heavy metals, making them unavailable to the plant roots, and may strongly bind a vast variety of harmful organic pollutants. Increasing SOC is an important goal in agriculture. The inclusion of mixtures of semi-perennial plant species and cultivars may strongly increase SOC and humic substance content in soils. To increase SOC, farmyard manure and its rotted or composted forms are superior compared to the separate application of straw and slurry to soil. The storage of carbon, mainly in organic form, in soils is very important in the context of the emission of greenhouse gases. Worldwide, soils release about 10 times more greenhouse gases compared to fossil fuel combustion. Small increments in SOC worldwide will strongly affect the concentration of atmospheric CO2. The public discussion on soil fertility and greenhouse gas emissionshas been politically controlled in a way that leaves the important and positive contribution of soil organic carbon and mainly humic substances partly misinterpreted and partly underestimated. [ABSTRACT FROM AUTHOR]

Although litter can regulate the global climate by influencing soil N2O fluxes, there is no consensus on the major drivers or their relative importance and how these impact at the global scale. In this paper, we conducted a meta-analysis of 21 global studies to quantify the impact of litter removal and litter doubling on soil N2O fluxes from forests. Overall, our results showed that litter removal significantly reduced soil N2O fluxes (−19.0%), while a doubling of the amount of litter significantly increased soil N2O fluxes (30.3%), based on the results of a small number of studies. Litter removal decreased the N2O fluxes from tropical forest and temperate forest. The warmer the climate, the greater the soil acidity, and the larger the soil C:N ratio, the greater the impact on N2O emissions, which was particularly evident in tropical forest ecosystems. The decreases in soil N2O fluxes associated with litter removal were greater in acid soils (pH < 6.5) or soils with a C:N > 15. Litter removal decreased soil N2O fluxes from coniferous forests (−21.8%) and broad-leaved forests (−17.2%) but had no significant effect in mixed forests. Soil N2O fluxes were significantly reduced in experiments where the duration of litter removal was <1 year. These results showed that modifications in ecosystem N2O fluxes due to changes in the ground litter vary with forest type and need to be considered when evaluating current and future greenhouse gas budgets. [ABSTRACT FROM AUTHOR]

Degraded soils (including salinized, eroded, and low organic matter) resulting from natural and human effects are universal in arid and semi-arid regions all over the world. Bentonite and humic acid (BHA) are increasingly being tested to remediate these degraded lands, with potential benefits on crop production and soil health. A field study was conducted to quantify the effects of BHA application at six rates (0, 6, 12, 18, 24, and 30 Mg ha−1) on (i) dynamic changes in soil properties and (ii) oat crop productivity parameters in a dryland farming ecosystem. The specific objective of this paper was to determine the residual effects four to five years after a one-time BHA application on soil health and crop performance. The findings demonstrated that with the increasing rates of one-time BHA application, soil profile water storage displayed a piecewise linear plus plateau increase, whereas soil electrical conductivity, pH, and bulk density were all reduced significantly (p < 0.05) in the 0–20 cm and 20–60 cm layers. The improved soil environments gave rise to an increased activity of soil enzymes urease, invertase, and catalase that, respectively, reached peak values of 97%, 37%, and 32% of the control at the rates of 18 to 24 Mg BHA ha−1. In turn, this boosted soil nutrient turnover, leading to a 40% higher soil available P. Compared with the control treatment, application of BHA at the estimated optimum rate (roughly 24 Mg ha−1) increased grain yield by 20%, protein yield by 62%, water use efficiency by 41%, and partial factor productivity of N by 20%. The results of this study indicated for the first time that a one-time BHA application would be a new and effective strategy to combat land degradation and drought, and promote a sustainable soil micro-ecological environment in dryland agroecosystems under a varying climate scenario. [ABSTRACT FROM AUTHOR]

This paper presents a deep analysis of the accessory genome of an economically promising strain of Ensifer (Sinorhizobium) meliloti, L6-AK89, obtained as a result of next-generation high-throughput sequencing (MiSeq, MinIon). Strain L6-AK89 is a StrR mutant of the native strain CIAM1775, a symbiont of Medicago lupulina that adapted to a saline and arid habitat in NW Kazakhstan. CIAM1775 is an effective inoculant of M. lupulina cv. Mira (fodder type standard), cultivated on moderately acid soils in the NW agricultural region of Russia. Strain L6-AK89 makes it possible to obtain the expected high (>150%) increases in dry mass of the same plant variety in plant tests. The L6-AK89 genome has an increased proportion of sequences related to the accessory elements relative to reference strain Rm1021, 7.4% versus 4.8%. A set of 53 nod/noe/nol/nif/fdx/fix genes and 32 genes involved in stress tolerance together with 16S rRNA and recA–atpD–glnII–gyrB–dnaJ were evaluated. The high symbiotic efficiency of L6-АК89 with hop clover is most likely due to unique features of its genome, in combination with structural differences in its nod and stress-related genes, as well as unique clusters of quorum-sensing genes and osmoprotector synthesis. [ABSTRACT FROM AUTHOR]

The current opinion and position paper highlights (1) correct assignation of indicator phospholipid fatty acids (PLFA), (2) specificity and recycling of PLFA in microorganisms, and (3) complete extraction and detection of PLFA. The straight-chain PLFA 14:0, 15:0, 16:0, and 17:0 occur in all microorganisms, i.e., also in fungi and not only in bacteria. If the phylum Actinobacteria is excluded from the group of Gram-positive bacteria, all remaining bacteria belong to the bacterial phylum Firmicutes, which should be considered. The PLFA 16:1ω5 should be used as an indicator for the biomass of arbuscular mycorrhizal fungi (AMF) as there is no experimental evidence that they occur in marked amounts in Gram-negative bacteria. Fungal PLFA should embrace the AMF-specific 16:1ω5. In the presence of plants, ergosterol should be used instead of the PLFA 18:2ω6,9 and 18:1ω9 as fungal indicators for Mucoromycotina, Ascomycota, and Basidiomycota. The majority of indicator PLFA are not fully specific for a certain microbial group. This problem might be intensified by recycling processes during decomposition to an unknown extent. Soil handling and extraction conditions should be further optimized. The reliability and accuracy of gas chromatographic separation need to be regularly checked against unintentional variations. PLFA analysis will still be of interest over the next decades as an important independent control of DNA-based methods. [ABSTRACT FROM AUTHOR]

The paper deals with of the relations between the forest ecosystem, calcareous rocks and content and composition of soil organic matter in the Golo Bardo area in West Bulgaria. In that area Rendzinas are used mainly for forestry, viticulture and pastures. A specific study based on the accumulation of soil organic matter according to the data on the composition of the soil organic acids. The research on the soil organic matter composition provided information on the course of the humification processes in studied soils. Soil organic matter accumulation in Rendzinas depends on different factors, such as land use and climatic conditions. Soil has rapid transformations of organic residues and strongly decomposed plant tissue predominates. There are often signs of active work of the soil mesofauna. Studied soils have good reserves of organic carbon high degree of humification. The organic carbon content varies in a wide range from 0.8 to 7.2 %. The humic acids prevail over fulvic acids, and the degree of humification is higher in deeper horizons. According to the C/N ratio the humus type is Mull in almost all horizons. Studied soils are biologically active that have favorable impact over the soil structure and vegetation. Rendzinas have high potential of organic carbon sequestration. [ABSTRACT FROM AUTHOR]

The paper presents a synthesis of the research consisting in a complex capitalization of a brucitic limestone deposit from Romania, in environmental protection, respectively of the complex processing possibilities for using the final products could in a very well defined direction such as: the getting of MgO with 99% purity from a brucitic concentrate with 38-40% MgO content; the getting of a fertilizer containing struvite, limestone and microelements with benefit effects on the acid soils amelioration and on plants growth. The research allowed the establishing of a complex system of three technologies, respectively, one of brucitic limestone processing, the second of magnesia obtaining by brucitic concentrate leaching with carbon dioxide and the third, that of getting a double-role agricultural fertilizer (manure for plants growth and acid soils neutralizer). [ABSTRACT FROM AUTHOR]

[Objectives] This paper was aimed to study the remediation effects of phosphate-solubilizing fungi and bone char in different soils. [Methods] Three different types of lead-contaminated soils (neutral yellow brown soil, alkaline sand soil and acidic red soil)were mixed with the bone char sintered at different temperatures. We measured the contents of phosphorus and lead, and the remediation differences of different soils. The Pb bioavailability of lead-contaminated soil was then determined by planting non-heading Chinese cabbage. The application potential of compound remediation materials was confirmed by adding compound remediation agents to the soil with the best remediation effect. [Results] The bone char had the best effect of promoting the release of phosphorus in yellow brown soil, and the available phosphorus content was 64 times higher than that of the control, showing a high potential of lead remediation. The pH of yellow brown soil was neutral, and the available P in the soil would not be fixed by Ca, Fe, Al, etc., thus increasing the probability of its reaction with Pb. When bone char was solely used, the material treated at 200-300 ℃ had qualified remediation effect. We planted non-heading Chinese cabbage to verify the bioavailability of lead in yellow brown soil after bone char application. It was observed that addition of a certain proportion of bone char to yellow brown soil (the initial mass ratio of bone char to lead was over 0.5:1) could not only increase the absorption of phosphorus by 2.0 to 3.5 times, but also reduce the absorption of lead by non-heading Chinese cabbage(content of lead in pakchoi leaves was reduced by 70% to 80% compared with blank treatment). A composite of bone char and Aspergillus niger was further applied to yellow brown soil, and the effective lead was reduced to 14.36 mg·kg-1. In particular, the growth of the A. niger proved the remediation potential of the composite. [Conclusions] The composite of bone char and A. niger was suitable for lead remediation in neutral soils, and the suitable heating temperature for preparing bone char was 200-300 ℃. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to explore the effects of manganese stress on acid soil nitrogen conversion, enzyme activity and sugarcane nitrogen absorption and utilization, and provide a reference for the rational fertilization of sugarcane on acid soil. [Method JSimula- ted acidic soil manganese stress cultivation experiment in the indoor, and the sugarcane pot experiment in the glasshouse were carried out, and the difference of soil nitrogen component content, pH and soil enzyme activity under manganese stress and its relationship with sugarcane nitrogen absorption and accumulation relationship were measyured and analyed. [Result] Manganese stress significantly increased soil ammonium nitrogen content and net ammonification rate(P < 0. 05,the same as below), significantly reduced soil nitrate nitrogen content and net nitrification rate, and significantly increased soil net mineralization rate. At the same time, manganese stress significantly reduced soil urease activity and significantly increased soil invertase activity, but had no significant effect on soil protease activity (P >0. 05). The results of correlation analysis showed that soil urease activity was significantly and extremely (P < 0. 01, the same as below) positively correlated with soil ammonium nitrogen content and pH, soil protease activity was significantly positively correlated with soil ammonium nitrogen content, and extremely and significantly negatively correlated with soil nitrate nitrogen content and net nitrification rate respectively. Under manganese stress, sugarcane plant height, biomass, plant nitrogen accumulation and nitrogen absorption efficiency were significantly reduced. [Conclusion] Manganese stress can inhibit the nitrification of acid soils, reduce the conversion of ammonium nitrogen to nitrate nitrogen, and at the same time reduce the activity of soil urease and increase the activity of soil invertase, thereby reducing the available nitrogen content of sugar- cane in acid soil, reducing the absorption and utilization of nitrogen by sugarcane. [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]

Biochar is produced from organic materials by pyrolysis specifically for soil improvement. Interactions with beneficial outcomes between biochar and soil can arise within a short time but it is uncertain whether the effects are similar in all soil types and at different time-scale. The objective of this study was to evaluate the short-term and mid-term effects of biochars from different feedstocks (grain husks and paper fibre sludge, post-treated grain husks and paper fibre sludge, woodscreenings) on the soil physico-chemical, biological and ecotoxicological properties. As part of a complete scale-up technology, aiming improvement of an acidic sandy soil, a 12-month microcosm experiment was conducted with combined application of biochars, compost and fertilizer. The applied multiparameter approach made possible the selection of the most optimal treatment. All the three biochars had favourable influence on the soil, but the effects were different in terms of extent and time. Although the biochar from woodscreenings had not the most promising short-term effects, but combined with fertilizer at 0.5 w/w% biochar rate it was the most favourable treatment after 12 months. The grain husk and the paper fibre sludge biochar at 1 w/w% rate could also efficiently improve soil parameters and functions. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of de-inking paper sludge (DPS) and sewage sludge (SS) application on soil properties, and durum wheat growth and yield. A pot experiment was performed on Calcaric cambisol (clCM) and Cromic Luvisol (coLV) soils. Three DPS rates (0, 30, and 60 Mg ha−1) were studied with and without nitrogen fertilizer (280 kg NH4NO3 ha−1). DPS was also mixed with SS at two rates (5 and 10 Mg ha−1) to highlight the benefits of organic nitrogen compared to mineral nitrogen. DPS improved total organic carbon and nitrogen, mineral nitrogen, and soils cation exchange capacity, the 30% rate provided the greatest improvement in both soils. DPS increased grain and root P, K, Ca, and Mg contents in both soils. It also increased wheat straw N, P, Mg, and Ca for the same soil compared to the control. Mixed DPS treatments with nitrogen fertilizer enhanced grain yield by up to 38% and increased root biomass in the studied soils. Thus, DPS is a potential source of organic matter and a liming agent for acid soils when appropriate supplemental fertilizer is provided. [ABSTRACT FROM AUTHOR]

A three-year field experiment was conducted to analyze the effects of straw enrichment and deep incorporation on the humus composition and the structure of humic acid (HA) in black soil. The differences in the HA structure between different straw returning methods were detected by three-dimensional fluorescence spectroscopy and 13C NMR technology. The purpose of this paper is to provide a theoretical basis and data support for improving the straw returning system. Four different treatments, including no straw applied (CK), straw mulching (SCR), straw deep ploughing (MBR), and straw enrichment and deep incorporation (SEDI: harvested the corn straw from four rows together with a finger-plate rake and then crushed and buried them in one row in the 20∼40 cm deep level in the subsoil with a wind-driven input cylindrical plough), were used in this study. Our results showed that compared to CK treatment, SEDI significantly increased the contents of organic carbon (SOC), soil humic acid carbon (HAC), fulvic acid carbon (FAC), and humin C content (HM-C) in the subsurface soil layer by 27.47%, 34.33%, 19.66%, and 31.49%, respectively. Among all the straw returning treatments, SEDI treatment had the most significant effect in increasing the contents of HEC, HAC, and FAC. Straw returning not only reduced the degree of condensation and oxidation of the HA structure but also increased the proportion of alkyl C and enhanced the hydrophobicity of the HA structure in subsurface soil. Moreover, SEDI treatment significantly increased the proportion of aliphatic C/aromatic C of the HA structure in subsurface soil and improved the aliphatic property of HA, which had a significant effect on the HA structure compared to other treatments. [ABSTRACT FROM AUTHOR]

The study shows the impact of soil treatment with industrial waste on the nutrient content and growth process of green oat plants. The industrial process of carbon dioxide leaching from dolomites produces magnesium carbonate and oxide and calcium carbonate as waste. Both waste types result in the industrial processes of manufacturing magnesium compounds from dolomites as waste product and deposits on the industrial equipment. Besides calcium carbonate the waste contains magnesium carbonate. The difference between the two waste types lies in the double magnesium content, established for the crusts deposits. The research pursues the result of treating soil with industrial waste, managed as four different doses, on soil features like reaction and calcium-, magnesium content as well as on the nutrition process of oat plants, stand out as growth process and calcium- magnesium uptake. The experimental alternatives consists of treating soil with four different waste doses. The results praise that, after soil treatment with several doses of waste, acid soil becomes neutral, while an increase for calcium and magnesium content in soil was also observed. For green oat plants, the growth process by mean of some vegetation characteristics and essential elements uptake was studied. The impact of soil treatment with waste as fertilizer on plant content differs depending on the pursuit nutrient element. The results show that calcium uptake increased by 117% and 72% for magnesium uptake was established. The consequence on the development of green oat plants reveals a positive effect on germination and risen plants, simultaneous with dry matter content decrease. The originality of this paper consists in the revaluation of this industrial waste in agriculture both as a fertilizer and an amendment for acid soils. The importance of this study lies in establishing a new technology that can be used in agriculture by specifying the suitable dose of waste, usage manner and application frequency. [ABSTRACT FROM AUTHOR]

Public concerns over environmental protection have increased after Fukushima accident. The soil-plant transfer factor (Fv) is a critical parameter for environmental risk assessment. 137Cs Fv values determined in acid Brazilian soils could be two orders of magnitude higher than Fv values measured in soils affected by the Chernobyl accident. This paper studied the behaviour of 90Sr in Brazilian soils where very few 90Sr Fv data is available. All classes of studied soils (Ferralsol, Acrisol and Nitisol) showed that more than 80% of total 90Sr in soils remains potentially mobile, mainly at the bioavailable phase, more than 2 years after soil contamination in an experiment conducted in lysimeters. Higher 90Sr Fv for maize and cabbage was observed in the acid soils with low content of exchangeable Ca, lower Fv values occurred at Nitisol, the subtropical soil type. It seems that the behaviour of 90Sr in these soils are mainly controlled by ionic competition mechanisms occurring for root uptake and sorption sites, with stable Sr and major nutrients (Ca, Mg and K). The mineralogy also seems to play a relevant role, since goethite rich clay soil presented 90Sr Fv values higher one or two orders of magnitude than 90Sr Fv values observed at clayed soil goethite rich with trace of vermiculite, for all studied crops. The high rate of 90Sr migration down the soil profiles observed for the studied soils during the 2 first years after contamination suggests a high rate of transfer to groundwater, even transfer to leafy crop group can be also a relevant pathway. In the present study, maize, among other plant species, presented the lowest Fv values, even when compared with maize cultivated in temperate soil. Our results suggest that stable Sr may not be a very good analogue of 90Sr for determining plant Fv values: geometric mean of stable Sr Fv for maize was Fv maize = 6.3E-1 ± 2.1E0 (n = 8) and for 90Sr was Fv maize = 1.8E-2 ± 2.5E0 (n = 16), geometric mean of stable Sr Fv for cabbage was Fv cabbage = 1.4E0 ± 3.9E0 (n = 17) and for 90Sr was Fv cabbage = 7.9E-1 ± 4.4E0 (n = 18). [Display omitted] • Transfer of 90Sr and stable-Sr was studied in Brazilian soils. • 90Sr in Brazilian soils (Ferralsol, Nitisol, Acrisol) had a high potential mobility. • Mineralogy plays a key role in determining 90Sr availability for plant uptake. • Stable-Sr is not a good analogue for 90Sr plant uptake. • A high rate of 90Sr migration down the soil profile was observed. [ABSTRACT FROM AUTHOR]