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Biochar is widely used to maintain crop yields and the sustainability of agroecosystems due to its characteristics. However, its effect on vegetable yield and quality in southern acidic soils has not been fully elucidated. The effects of two kinds of biochar application rates (3 t ha−1 and 12 t ha−1) on the nutrient availability, nutrient absorption, yield, and fruit quality of sandy acid oxide soil in South China were studied in a 2-year field experiment using two varieties of wax gourd (Tiezhu No. 2 and Dadao). The results showed that optimized fertilization (OPT, nitrogen, phosphorus, and potassium were reduced by 20.0%, 20.6%, and 21.1%, respectively) did not reduce the yield of the different varieties of wax gourd compared to FP (farmer practice). On the basis of the OPT treatment, the application of biochar increased the yield of Tiezhu No. 2 and Dadao wax gourd by 16.0–27.3% and 7.7–13.3%, respectively. The increase in yield was attributed to the improvement in soil organic carbon content which increased by 4.5–19.7%, nutrient effectiveness (NO3−-N and Olsen-P content enhanced by 23.7–27.0% and 15.3–23.4% in Tiezhu No. 2), and nutrient uptake (N, P, K, Ca, and Mg accumulation increased significantly by 21.1%, 46.1%, 36.8%, 25.7%, and 31.9%, respectively) by the plant after the biochar application. Different types of biochar also have some differences in these three aspects. Specifically, under the same dosage, rice biochar has a more significant effect on increasing the yield of winter melon, and has a better effect on the improvement of soil physical and chemical properties, while sawdust biochar has a more significant effect on nutrient absorption. In addition, the commercial quality, namely hardness and glossiness, and the nutritional quality, namely soluble sugar, soluble protein, VC content, and sugar–acid ratio of wax gourd fruits, were significantly improved after the biochar application. In summary, biochar application on acidic soils in South China could achieve a win–win situation in terms of increasing soil nutrient effectiveness to improve vegetable yield and quality while reducing chemical fertilizer. [ABSTRACT FROM AUTHOR]

Exploring the effects of different additives on the improvement of newly cultivated farmland in mountainous areas can provide rational soil fertilization plans for regions lacking means of production. We conducted a paddy planting experiment in Ankang City, Shaanxi Province. Six treatments were set up, including sole chemical fertilizer (CK); fertilizer + bacteria agent (NB); chemical fertilizer + alginate bio-organic fertilizer (NO); fertilizer + fulvic acid biomass nutrient solution (NF); chemical fertilizer + acid soil conditioner (NC); fertilizer + silicon–calcium–magnesium–potassium fertilizer (NSi). We collected topsoil samples after paddy harvest, analyzed their physical, chemical, and biological properties, and selected indicators to construct a Total Data Set (TDS) and a Minimum Data Set (MDS). The Soil Quality Index (SQI) was used to evaluate the soil improvement effects after different fertilization regimes. The SQI calculated by the TDS and the MDS showed that the SQI after NF treatment was higher than that under other treatments. The SQI based on the TDS (SQITDS) and the SQI based on the MDS (SQIMDS) were significantly positively correlated with yield. The SQI calculated based on both the TDS and the MDS can objectively reflect the soil fertility quality. The paddy yield and total dry matter accumulation were the highest under the NF treatment, and the SQI was the largest. Thus, the effect of chemical fertilizer combined with fulvic acid biomass nutrient solution on soil fertility was the most significant. [ABSTRACT FROM AUTHOR]

Aluminum (Al) toxicity is one of the major constraints for crop production in acid soils, Al-ACTIVATED MALATE TRANSPORTER1 (ALMT1)-dependent malate exudation from roots is essential for Al resistance in Arabidopsis, in which the C2H2-type transcription factor SENSITIVE TO PROTONRHIZOTOXICITY1 (STOP1) play a critical role. In this study, we reveal that the RAE1-GL2-STOP1-RHD6 protein module regulated the ALMT1-mediated Al resistance. GL2, STOP1 and RHD6 directly target the promoter of ALMT1 to suppress or activate its transcriptional expression, respectively, and mutually influence their action on the promoter of ALMT1 by forming a protein complex. STOP1 mediates the expression of RHD6 and RHD6-regulated root growth inhibition, while GL2 and STOP1 suppress each other's expression at the transcriptional and translational level and regulate Al-inhibited root growth. F-box protein RAE1 degrades RHD6 via the 26S proteasome, leading to suppressed activity of the ALMT1 promoter. RHD6 inhibits the transcriptional expression of RAE1 by directly targeting its promoter. Unlike RHD6, RAE1 promotes the GL2 expression at the protein level and GL2 activates the expression of RAE1 at the transcriptional level by directly targeting its promoter. The study provides insights into the transcriptional regulation of ALMT1, revealing its significance in Al resistance and highlighting the crucial role of the STOP1-associated regulatory networks. This study has identified new regulators, such as RHD6 and GL2, involved in the regulation of the RAE1-STOP1-ALMT1 module, contributing to Al resistance. It has also established a complex transcriptional network that controls STOP1-dependent ALMT1 expression, offering new insights into Al resistance and signaling. [ABSTRACT FROM AUTHOR]

Background: Striga asiatica (L.) O. Kuntze is a traditional medicinal plant rich in flavonoids, which has various pharmacological effects such as anti-hepatitis and antioxidant activities. However, there is a scarcity of resources, and artificial cultivation has not yet been achieved. This study explored the association between flavonoid metabolites and soil physicochemical properties and trace elements in different habitats, with the aim of offering theoretical guidance for the high-quality artificial cultivation of S. asiatica. Results: The results showed that S. asiatica has low requirements for soil fertility and prefers to grow in acidic soil with high contents of potassium and available potassium, while low contents of phosphorus, nitrogen and alkali hydrolyzed nitrogen. Additionally, 1592 kinds of metabolites were identified from S. asiatica, including 78 flavonoids. Conclusions: The flavonoid metabolites were strongly related to soil factors. Reasonable application of nitrogen and potassium fertilizers as well as controlling the contents of sodium, manganese and boron in the soil, can promote the synthesis of flavonoid metabolites in the plant. Moreover, kaempferide, glycitein, luteolin, apigenin and genistein may be the metabolic markers for identifying different regions. [ABSTRACT FROM AUTHOR]

Three successive vegetable pot experiments were conducted to assess the effects on the long-term immobilization of heavy metals in soil and crop yield improvement after the addition of peanut shell biochar and an alkaline mineral to an acidic soil contaminated with lead and cadmium. Compared with the CK treatment, the change rates of biomass in the edible parts of the three types of vegetables treated with B0.3, B1, B3, B9, R0.2 and B1R0.2 were −15.43%~123.30%, 35.10%~269.09%, 40.77%~929.31%, −26.08%~711.99%, 44.14%~1067.12% and 53.09%~1139.06%, respectively. The cadmium contents in the edible parts of the three vegetables treated with these six additives reduced by 2.08%~13.21%, 9.56%~24.78%, 9.96%~35.61%, 41.96%~78.42%, −4.19%~57.07% and 12.43%~65.92%, respectively, while the lead contents in the edible parts reduced by −15.70%~59.47%, 6.55%~70.75%, 3.40%~80.10%, 55.26%~89.79%, 11.05%~70.15% and 50.35%~79.25%, respectively. Due to the increases in soil pH, soil cation-exchange capacity and soil organic carbon content, the accumulation of Cd and Pb in the vegetables was most notably reduced with a high dosage of 9% peanut shell biochar alone, followed by the addition of a low dosage of 1% peanut shell biochar blended with 0.2% alkaline mineral. Therefore, the addition of a low dosage of 1% peanut shell biochar blended with 0.2% alkaline mineral was the best additive in increasing the vegetable biomass, whereas the addition of 9% peanut shell biochar alone was the worst. Evidently, the addition of 0.2% alkaline mineral can significantly reduce the amount of peanut shell needed for passivating heavy metals in soil, while it also achieves the effect of increasing the vegetable yield. [ABSTRACT FROM AUTHOR]

Humus materials are considered complex organic substances generated through a chain of chemical reactions and responsible for many processes in soil that ultimately govern soil health. The structural and functional characteristics of humus depend upon the location, quality, and microbial abundance of the soils. However, the differential characteristics of soil organic matter, seasonal changes, parent rock, plant cover, microbial abundance, and anthropogenic activities majorly affect it. The present study has aimed toward the extraction of humus from five different locations in the Delhi region of India and their characteristics were investigated through elemental analysis, Fourier Transform infrared (FT-IR) spectroscopy, and UV spectroscopy. The results showed that there was a higher degree of unsaturation detected in the Forest soil sample. The results of FT-IR showed the presence of characteristic peaks of humus in the samples however the intensity of bands was weak in sample disposable site soil sample and clayey soil sample due to the variation in soil physicochemical properties. The study also aimed to assess the growth of Oryza sativa (rice) plants observed in the hydroponics system. The significant finding was observed with the forest soil sample in 1000 mgL-1 and treatment in which the growth was minimum in clayey soil of 1500 mgL-1. Our investigation infers the diverse nature of humus in different soils and its implications for plant growth, highlighting the importance of understanding soil organic matter for sustainable agriculture and soil health management. [ABSTRACT FROM AUTHOR]

Tobacco, a pivotal economic crop in China, faces the challenge of securing high-quality raw materials for its industry due to unbalanced and inefficient nitrogen (N) application. To assess the impact of fertilizer management and soil factors on the yield and quality of flue-cured tobacco (FCT), a meta-analysis was conducted across 82 peer-reviewed research studies. The findings demonstrated that both fertilizer management and soil properties exerted a significantly greater influence on yield (63.13% and 62.05%, respectively) than the proportion of superior and medium tobacco (PSMT) (23.57% and 23.83%, respectively). Multiple models were conducted to analyze the N application rate for maximum yield and PSMT, respectively, resulting in an optimum range from 90 to 100 kg N ha−1. The highest yield and PSMT increments were observed with fertilizer timing (FT) applied twice, a basal fertilizer ratio (BFR) exceeding 50%, and a soil pH below 6.5. The nicotine content escalated with increasing N application rates (NR) and soil nitrogen content, peaking at NR over 120 kg N ha−1 and soil total nitrogen (TN) above 2 g kg−1. Stepwise regression modeling indicated that nicotine content was positively influenced by fertilizer management factors (including NR, fertilizer timing, and BFR), as well as initial soil nitrogen content (AN and TN). However, it was negatively correlated with available potassium (AK). Therefore, the results of this meta-analysis suggest that effective fertilizer management, slightly acidic soils enriched with AK, and lower N supply capacity are crucial for enhancing leaf quality while reducing nicotine content. This approach promises improved economic and environmental returns for the tobacco industry in China. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Red mud is a solid waste of bauxite processing by Bayer process which involves caustic digestion of Al-containing mineral for alumina production. The global inventory of red mud waste reached an estimated amount of 4 billion tons in 2015, increasing at an approximate rate of 120 million tons per year. Therefore, its management is becoming a global environmental issue for the protection of environment, and the need for awareness in this regard is becoming crucial. Although red mud is not considered as a hazardous material in many countries, its high alkalinity and fine particle size may pose significant environmental threat, and it is found to be an interesting material for environmental remediation purposes due to rich iron content. This paper provides a review of possible remedial applications of red mud in various environmental compartments. Modification of red mud creates novel opportunities for cost-effective and efficient removal of metal ions, inorganic anions, dyes, and phenols from wastewater and acid mine drainage. Re-vegetation of red mud disposal sites, treatment of metal-contaminated acidic soils presents the usefulness of this material but less research has been done so far to investigate its use in the stabilization of polluted sediments. On the other hand, leaching and eco-toxicological tests have also revealed that red mud does not pose high toxicity to the environment making it suitable for the treatment of contaminated media. Nevertheless, neutralization of red mud is recommended for its safe disposal and secure application in any environmental media. [ABSTRACT FROM AUTHOR]

The molecular structure of humus acids remains one of the most challenging issues in the soil science. The focus of the current research lies in defining the molecular and supramolecular structure of soil humus acids. This paper provides a brief review of the current understanding of the problem and shares findings of the elemental and X‐ray structural analysis of humic and fulvic acids extracted from Chernozems and Chestnut soils in the Rostov region. This region occupies a large area of the South‐European Russia. Humic acids in the studied soils have reduced carbon content compared to average parameters for these soil types. The supramolecular organization of humic acids in three‐dimensional space contains two to four layers of condensed aromatic systems supplemented by a network of chain fragments of different regularity and length. Parameters of this structure vary for soils of different genesis and genetic horizons. However, interplanar distances are fixed in the range of 0.349 to 0.371 nm. Thickness of the carbon network band increases with the benzoidicity level of humic acids. The obtained results confirm the specific matrix structure of humic acid molecules. Considering currently available scarce data these findings are valuable and unique. Our findings are consistent with the general hypothesis about the supramolecular nature of humic substances. [ABSTRACT FROM AUTHOR]

In order to investigate the function of, biochar and fulvic acid on improving coastal salty, alkalinity land, this paper adopted field corn planting experimental method in June 2015, and set up 6 treatments: CK, BC1, BC2, FA, BC1+FA, BC2+FA,applying biochar 7.5 t/ hm² (BC1), 30 t/ hm² (BC2), fulvic acid 1.5 t/ hm² (FA) and their combinations, and studied the effects of additional materials on characteristic indexes of important soil sanility, alkalinity situation. The results indicated that BC2 treatment could reduce soil bulk density, but soil bulk density was not reduced under treatment of low biochar application quantity (BC1), and soil in research area showed a gradual degradation state of natural hardening. With the increase of biochar applying quantity, soil water holding capacity showed a degeneration tendency. Applycation of biochar and fulvic acid significantly improved the organic matter contents in soil, which was the highest level under BC2+FA condition, reaching 6.31 g/ kg. Among all treatment, the phenomenon of periodic desalting and accumulation of salt in the surface soil showed an identical rule, but the salt accumulation under BC1+FA and BC2+FA treatments was obviousely lower than that of the other treatments. The results indicated that applycation of biochar and fulvic acid could increase soil fertility, improve soil structure, restrain salt accumulation and was in favour of remoulding coastal beach saline, alkali land for rapid arable land utilization. The treatment of 30 t/ hm² biochar combined with 1.5 t/ hm² fulvic acid had the best result. [ABSTRACT FROM AUTHOR]

Super-resolution technology is a method of reconstructing corresponding high-resolution images from observed low-resolution images. It has important application value in monitoring equipment, satellite images and medical images. In this paper, the author analyzes the quorum sensing and image simulation of plant rhizosphere microorganisms based on image compression sensing. By constructing an image algorithm based on compressed sensing, the performance of image recognition and analysis can be effectively improved. Quorum sensing (QS) is the physiological behavior of bacteria that can be regulated by gene expression through the proliferation of small molecule tautological signal molecules to perceive cell population density changes. On this basis, the population induction effect of acid red soil on plant rhizosphere microorganisms was analyzed. The results include: (1) The dynamic changes of Awls content in rhizosphere soils of different plant species in acid soils at different growth stages were studied. (2) The molecular mechanism of plant-soil-microorganism interaction under acid stress was explored. (3) The effects of environmental factors on the diversity of bacterial communities of animals and plants were explained by rank sum test. The results of this study can be used for reference in analyzing the symbiotic mechanism of plant rhizosphere microorganisms in soil. [ABSTRACT FROM AUTHOR]

Vascular vegetation experiments were carried out with a universal grass mix (Lolium perenne rosemary 30%, Lolium perenne esquire 25%, Festuca rubra casanova 25%, Festuca rubra gondolin 20%). In this study were used mineral waste with a strong acid reaction and soils from three regions - Sofia, Chelopech and Gorubliane. The soils had different contents of humus, nitrogen, mechanical composition and soil reaction. The plants had the best growth on the soil from Sofia, which had the highest humus and nitrogen content. The differences in fresh and dry weight of above-ground biomass of plants growing on different soils in June and July were much more significant than those obtained in October. Biomass data for the autumn season suggests that higher clay content and higher soil reaction of soil from Gorubliane significantly reduced the amount of bioavailable for plants pollutants fraction. The second part of this paper focuses on measurements and analysis of thermal processes in the active layer. The objectives are to determine the soil thermal properties, heat transfer processes and to use a thermal model, determine soil surface heat flow under atmospheric forcing. This model is validated using soil temperature and micrometeorological data from a field measurements. [ABSTRACT FROM AUTHOR]

The use of various types of biomass for energy production provides great prospects for reducing the consumption of fossil fuels and the negative impact on the environment. However, the use of biomass, in particular agromass for this purpose, results in relatively large amounts of bottom ashes and fly ashes, the composition and properties of which also raise a number of additional environmental problems. The composition and properties of fly ash are investigated in the paper, taking into account the possibilities of utilizing them for soil fertilization and other applications. Fly ash samples were collected from bunkers of flue gas cleaning equipment (electrostatic precipitator and cyclones) installed after water heating boilers, which are firing wood chips and chuffed straw. The composition of fly ash was determined using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS) while particle size distribution was obtained using scattered-light aerosol spectrometer. Electrical Low Pressure Impactor (ELPI) was used to separate fly ash into 14 groups by particle diameter, and the analysis of their composition showed differences in the composition of the fly ash collected in cyclones and Electrostatic Precipitators (ESP). An analysis of the composition of samples in regard to the existing heavy metals norms and considering concentrations of elements beneficial to the growth of plants, enables to prepare recommendations for fertilization. The determined alkalinity of fly ash pH 13 confirms the possibility of their use for reducing soil acidity. The analysis of fly ash composition has shown that they contain elements, important for plant growth (Ca, Mg, K, P, N, S), and their concentrations determine the further use for soil quality improvement because the amount of these elements in the acid soils is reduced. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central European Agriculture is the property of Journal of Central European Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

BACKGROUND AND OBJECTIVES: To meet the needs of the global population (9.7 billion people) until 2050, a 45 percent increase in corn production is required. Efforts to enhance corn production may be informed, among others, by precise nitrogen management. The objective of this study is to investigate nitrogen dynamics and accurate nitrogen nutrient management in corn farming through the utilization of a leaf chlorophyll meter and nitrogen response assessments in order to forecast corn yield in tropical upland acid soils. METHODS: The current study was conducted in an Ultisol and verified in an Oxisol. The trial was arranged in a randomized completely block design with eight treatments: 0, 45, 90, 135, 180, 225, 270, and 315 kilograms of nitrogen per hectare, repeated three times. The chlorophyll content of corn leaves was measured at 45 and 60 days after planting, using a chlorophyll meter. An analysis was conducted on the vegetative growth and yield, along with the nitrogen content in the soil, leaf, and grains. FINDINGS: The study found that the application of nitrogen fertilizer at the rate of 180 kilograms per hectare can alter nitrate concentrations in soil and significantly increase nitrogen uptake, growth, and corn yield. The nitrogen fertilizer application reached its peak at 274.5 kilograms per hectare, resulting in chlorophyll meter readings of 52.8 and a corn yield of 8.58 tons per hectare. The corn yield at the rate of maximum nitrogen fertilizer (8.58 tons per hectare) was not significantly different from that at the rate of 180 kilogrammes nitrogen per hectare (8.54 tons per hectare). A robust relationship was observed between corn yields and chlorophyll meter values, exhibiting a correlation coefficient 0.92. CONCLUSION: The study revealed that applying nitrogen fertilizer at the medium rate of 180 kilograms per hectare can increase in nitrogen uptake, growth, and corn yield on tropical upland acid soils. The corn yield did not show a notable variance between the nitrogen fertilization rate of 180 kilograms per hectare and the highest rate of 274.5 kilograms per hectare. In terms of sustainable agriculture management, the medium rate of 180 kilograms of nitrogen is recommended for maximizing crop yield on the upland acid soils and minimizing potential environmental impacts associated with the excessive use of fertilizers. A significant relationship exists between leaf chlorophyll meter measurements and corn yield, indicating that the chlorophyll meter can be utilized as a dependable instrument in the research area for establishing the most effective fertilizer levels. [ABSTRACT FROM AUTHOR]

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Acidic soils hamper maize (Zea mays L.) production, causing yield losses of up to 69%. Low pH acidic soils can lead to aluminum (Al), manganese (Mn), or iron (Fe) toxicities. Genetic variability for tolerance to low soil pH exists among maize genotypes, which can be exploited in developing high-yielding acid-tolerant maize genotypes. In this paper, we review some of the most recent applications of conventional and molecular breeding approaches for improving maize yield under acidic soils. The gaps in breeding maize for tolerance to low soil pH are highlighted and an emphasis is placed on promoting the adoption of the numerous existing acid soil-tolerant genotypes. While progress has been made in breeding for tolerance to Al toxicity, little has been done on Mn and Fe toxicities. More research inputs are therefore required in: (1) developing screening methods for tolerance to manganese and iron toxicities; (2) elucidating the mechanisms of maize tolerance to Mn and Fe toxicities; and, (3) identifying the quantitative trait loci (QTL) responsible for Mn and Fe tolerance in maize cultivars. There is also a need to raise farmers' and other stakeholders' awareness of the problem of Al, Mn, and Fe soil toxicities to improve the adoption rate of the available acid-tolerant maize genotypes. Maize breeders should work more closely with farmers at the early stages of the release process of a new variety to facilitate its adoption level. Researchers are encouraged to strengthen their collaboration and exchange low soil pH-tolerant maize germplasm. [ABSTRACT FROM AUTHOR]

Copyright of Zemdirbyste-Agriculture is the property of Lithuanian Research Centre for Agriculture & Forestry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Romanian Journal of Materials / Revista Romana de Materiale is the property of Foundation for Materials Science & Engineering Serban Solacolu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Soils exhibit undesirable volume changes when exposed to high concentrations of acids, which is manifested most frequently in the beds of foundations of industrial establishments associated with their production or use. However, control of this phenomenon has received less attention than it deserves. This paper aims to investigate the mineralogical and micro-structural changes occurred during the volume change behavior of phosphogypsum treated clayey soils contaminated with sulfuric acid and phosphoric acid solutions. Oedometer test results showed high swelling and low compressibility for acid contaminated soils than that of water. The change in microstructure towards flocculated fabric along with mineralogical transformations are responsible for the volume changes in soils. The mineralogical changes that affected the volume change behavior are discussed with FT-IR, XRD and SEM analysis. Phosphogypsum treatment was found to be effective in controlling volume changes in soils with phosphoric acid, whereas in the case of sulfuric acid found to be futile. [ABSTRACT FROM AUTHOR]

Arnica montana is an endemic species in Europe, widely spread in hundreds of sites. The populations of arnica are stable in some countries and endangered in others. The reasons of this decline are represented by its harvesting for medicinal purposes and, to some extent, by the habitat diminishing. The species is keen to the alpine and subalpine meadows, and to the acidic soils rich in nutrients. The arnica's preservation status is a favourable one in Romania due to its abundance. Nevertheless, in the near future its status should be thoroughly monitored as the specific habitats will begin their decline. The purpose of this scientific paper is to analyze the distribution area of this species within the investigated site, the types of habitats in which the species were identified, the relation between arnica and the environment, the identification of the possible menaces, and the new management regulations for a sustainable preservation. [ABSTRACT FROM AUTHOR]

This paper presents the results of experiments performed to determine how the quantity of the binder (bentonite) and the parameters of the laboratory roll press affect the quality of the briquettes obtained from limestone powder. These experiments aim to examine the conditions in which limestone briquettes are formed and to determine their use for agricultural purposes. During the experiments various mass fractions of bentonite was added to limestone (from 1 to 10 %), while the force of roll press drums ranged from 2 to 25 kN. The briquettes have been tested by applying scanning electron microscopy (SEM), differential thermal and thermogravimetric (DTA/TG) analyses, X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). Bentonite distribution was found to be uniform within the compact briquette structure. Formation of new compounds was not evidenced. The experiments also demonstrated that during briquetting, limestone properties remain unchanged, the changes are only physical, water solubility is not reduced, mechanical properties (impact resistance, compressive strength and abrasion resistance) are satisfactory by the transport and storage terms if the binder mass fraction is over 5% and the briquetting force exceeds 10kN and finally there is no loss due to wind dispersal during application. The only downside of the “green” briquettes obtained is the time required for their complete disintegration if totally immersed in water. [ABSTRACT FROM AUTHOR]

The concept of the soil phosphorus storage capacity (SPSC) was successfully used to evaluate the phosphorus (P) loss risk and the P retention capacity of acidic soil. This study extended the concept of SPSC from acidic soil to neutral or alkaline soil. A total of 95 surfaces (0-10 cm) soil samples were collected from the Yellow River Delta (YRD) for use in this study. Batch sorption experiments, correlation analysis, stepwise regression, and a split--line model were used to calculate the threshold value of the degree of P saturation (DPS). The SPSC was developed based on the DPS threshold value. Based on a DPS threshold value of 11.5%, we developed the following equation for calculating the SPSC: SPSC = (11.5% - soil DPS) × (0.113 × SOM (soil organic matter) + 1.343 × CaCO3). In the continuous system in this watershed, from wetland to farmland, the SPSC for vegetable fields (-94.7 ± 79.1 mg/kg) was lowest and that of the restored wetland (76.3 ± 26.1 mg/kg) was the highest. Along the transition zone in the YRD, both the natural soil development and human alternations significantly affected the soil P loss/retention capacity. In terms of P storage, the restored wetlands are the highlands for P retention and the vegetable fields contribute significantly to the P loss in the YRD. As a result, we strongly recommend that the restored wetlands be fully utilised for P retention and that P fertiliser no longer be applied to the vegetable fields to prevent P loss into the watershed. [ABSTRACT FROM AUTHOR]

Rhododendron delavayi Franch. predominantly thrives in broad-leaved evergreen forests and bushes at altitudes of 1,200–3,200 meters. It favors a cool, moist climate and thrives in acidic soils. Due to its high ornamental, medicinal, and scientific values, understanding its ecological needs and optimal cultivation ranges is crucial. This study analyzing the key environmental factors and their thresholds affecting its distribution and predicts the future potential habitats of R. delavayi using existing distribution data alongside current and projected climate data. The results indicate that the primary environmental influencers are soil pH (4.9–5.4), precipitation in the driest month (10–20 mm), and altitude, contributing 41.8, 24.1, and 18.3%, respectively. It also shows a declining trend in suitable habitats: from 27.75 × 104 km² under current conditions, to 3.69 × 104 km² by the 2050s, and further to 2.65 × 104 km² by the 2070s. [ABSTRACT FROM AUTHOR]

Limited knowledge is available regarding biochar (BC) obtained from beach-cast seaweed, which needs to be characterized to better prospect its potential applications. Beach-cast seaweed BCs were produced at two temperatures (300 and 600 °C) and two residence times (1 and 3 h). First, an extensive characterization of feedstock and their derived BCs was performed. Then, an incubation experiment was conducted to investigate the potential of these BCs as ameliorants in two acidic soils, classified as Umbrisols. Proximate and elemental analyses suggested the presence of more stable C structures in BCs at 600 °C with a high C, fixed carbon (FC) and low H, O and volatile matter (VM); additionally, thermogravimetric graphics showed less weight loss. Some features from the raw material were present in biochars obtained at 300 °C but absent at 600 °C. Dissolved organic carbon was much lower in BCs pyrolyzed at 600 °C than at 300 °C, suggesting the higher aromaticity of the former, allowing more resistance to water extraction. The breakdown of proteinaceous soluble materials after pyrolysis was revealed by fluorescence. Residence time caused minor effects in biochar properties compared to temperature. The soil pH and macronutrient availability of the two studied soils increased after beach-cast seaweed biochar addition. [ABSTRACT FROM AUTHOR]

This study investigated the effect of magnesium application on peanut growth and yield under two nitrogen (N) application rates in acidic soil in southern China. The chlorophyll content, net photosynthetic rate and dry matter accumulation of the N-sensitive cultivar decreased under reduced N treatments, whereas no effect was observed on the relevant indicators in the N-insensitive variety GH1026. Mg application increased the net photosynthetic rate by increasing the expression of genes involved in chlorophyll synthesis and Rubisco activity in the leaves during the pegging stage under 50%N treatment, while no effect on the net photosynthetic rate was observed under the 100%N treatment. The rate of dry matter accumulation at the early growth stage, total dry matter accumulation and pod yield at harvest increased after Mg application under 50%N treatment by increasing the transportation of assimilates from stems and leaves to pods in both peanut varieties, whereas no effect was found under 100%N treatment. Moreover, Mg application increased the NUE under 50%N treatment. No improvement of NUE in either peanut variety was found under 100%N treatment, while Mg application under the 50%N treatment can obtain a higher economic benefit than the 100%N treatment. In acidic soil, application of 307.5 kg ha-1 of Mg sulfate fertilizer under 50% reduced nitrogen application is a suitable fertilizer management measure for improving carbon assimilation, NUE and achieve high peanut yields in southern China. [ABSTRACT FROM AUTHOR]

Boron (B) is a micronutrient crucial for the growth, development, productivity, and quality of crops. However, in areas characterized by acid soil (pHwater < 5.0) and high rainfall, soil B concentration tends to decrease, leading to insufficient supply to crops. This study was aimed at determining the optimal rate of B fertilization to enhance Vaccinium corymbosum L. performance in acid conditions. One-year-old cultivars with contrasting Al resistance (Al-sensitive Star and Al-resistant Cargo) were used. Plants were conditioned in plastic pots containing 18 L of half-ionic-strength Hoagland solution (pH 4.5) for 2 weeks. Thereafter, the following B treatments were applied foliarly: control, without B application (distilled water), 200, 400, and 800 mg L−1 of B as Solubor® for up to 72 h. Photosynthetic performance, root and shoot B levels, antioxidants, and oxidative stress were evaluated. Root and shoot B concentrations increased with the increasing B application, being higher in leaves than in roots of both cultivars. Net photosynthesis decreased at 800 mg L−1 B supply and effective quantum yield of PSII at 72 h in all B treatments. Lipid peroxidation increased in both cultivars at 800 mg L−1 B treatment. Antioxidant activity increased in all B treatments in both cultivars; while, at 400 and 800 mg L−1 B, total phenols increased in leaves of cultivar Star and decreased in cultivar Cargo. In conclusion, optimal B foliar application for highbush blueberry appears to be around 400 mg L−1 B. The appropriate B foliar application could help mitigate potential stress-induced problems in highbush blueberry cultivation. However, the optimal foliar B application should be confirmed in field experiments to help the farmers manage B nutrition. [ABSTRACT FROM AUTHOR]

Food crop productivity is still low because of the decline of soil fertility in Ethiopia, particularly in north‐western Amhara. Fine‐tuning the source and rate of nutrients is required to solve soil fertility problems along landscape positions. Therefore, this study was initiated to investigate the need to apply selected nutrients to tef and wheat in acidic soils. This nutrient omission study was conducted in 74 farmers' fields of Gozamen and Machakel districts. The omitted nutrients were sulfur (S), zinc (Zn), and boron (B). Potassium (K) was added, consisting of N, P, K, S, Zn, and B (All+K). Nitrogen plus phosphorus (NP) and no fertilizer treatments were used as positive and negative controls, respectively. Furthermore, 50% and 150% of the All+K treatments were also included. The finding revealed that the application of different nutrient types at variable rates had a significant role in the grain and biomass yield of both test crops in the acidic soils. No tef yield and the lowest yield of bread wheat were obtained from the no fertilizer application treatment. The application of All+K had no significant yield advantage compared to NP fertilizer alone. This implies that N and P are the most yield‐limiting nutrients to produce tef and bread wheat, whereas KSZnB nutrients are not yield limiting. Therefore, refining the rates of N and P in acidic soils is needed for the economical use of fertilizers. Finally, applying blended fertilizers without empirical evidence is not recommended for smallholder farmers in the study area. Core Ideas: Right nutrient management maximizes crop yield.Identifying yield‐limiting nutrients in acidic soils is crucial.Understanding micronutrients' role boosts tef and wheat productivity.Major nutrients for tef and wheat production are identified in acidic soils.Assessing yield‐limiting nutrients is vital, with or without lime amendment. [ABSTRACT FROM AUTHOR]

Objective: Natural humic substances (HS) make up a significant part of the organic carbon of the biosphere. Considering the numerous significant ecological functions of HS, the lack of consensus either on the mechanisms of their formation or on the main features of their structure is somewhat paradoxical. Methods: Transmission electron microscopy (TEM) with contrast staining by uranyl acetate solution was used first time to study the morphological differences between soil humic acids (HAs) and fractions obtained by coupling preparative low-pressure size-exclusion chromatography and analytical polyacrylamide gel electrophoresis. Results and Discussion: Significant morphological differences between the fractions were observed and could be associated with their composition, established previously using several physicochemical methods. The Car (165–108 ppm)/Calk (108–0 ppm) ratio, or aromaticity index, calculated from the 13C NMR data, could be one of the indicators of the formation of various morphological structures. Conclusions: The obtained TEM results clearly confirm the supramolecular organization of soil HAs. [ABSTRACT FROM AUTHOR]

Vietnam's Mekong Delta region contains a sizable amount of acid-sulfate soil, which has properties that harm plants, such as low pH, aluminum and iron toxicity, hydrogen sulfide and sulfate acid. The study aims to gather helpful information about the problems with acid sulfate soils' chemical makeup so that suggestions can be made for improving these soils in the Mekong Delta. These methods mainly review studies and projects on the properties, constraints and management improvement of acid-sulfate soils and recommend the proper methods for sustainable use. The Mekong Delta contains many sulfidic or acid-sulfate-producing materials. Soils that contain acid sulfate are especially vulnerable to the consequences of climate change. Therefore, evaluating and predicting how acidic soil impacts soil quality and the affected factors such as drought, water scarcity, rainstorms, floods and saltwater intrusion are essential. Selecting cultivars that can withstand acid sulfate or salt is easy and inexpensive. Designing appropriate farming models is necessary in the interim. To correctly manage and exploit acid sulfate soils in the current situation, one must also be aware of their distribution, physicochemical makeup and biological properties. [ABSTRACT FROM AUTHOR]

Phosphorus availability is a serious problem for plants growing and grown in acidic soils of bogs, poor in macronutrients. The application of phosphorus fertilizers to such soils is unprofitable because of the physical and chemical properties of these soils, where phosphate is firmly bound to organic and inorganic compounds and becomes inaccessible to plants. Plants of the Vaccinium genus both from natural stands and commercial plantations may suffer from phosphorus deficiency, so they need to have a number of adaptations that allow them to efficiently extract phosphorus. This review addresses the following issues in relation to plants of the Vaccinium genus: sources of phosphorus for plants; the release of phosphate ions from soil components; the transport of phosphate ions into plants; and the importance of mycorrhiza in supplying phosphorus to plants. Thus, we sought to draw researchers' attention to sources and routes of phosphorus supply of plants of the Vaccinium genus and its unexplored aspects. [ABSTRACT FROM AUTHOR]

Amino acids aid in the growth and development of plants. Soil microbes outcompete plants for amino acids because they are great source of carbon and nitrogen for microbes. To overcome this problem, new agricultural practices are required. Due to minimal integration and ecological environmental preservation, polyethylene glycol is used as a soil-stabilizer to study its stabilization effect on soil. Six soil samples (0%-5% Polyethylene Glycol) were prepared to study the effect of polymer on soil-amino acid interaction. Five non-polar amino acids, viz., glycine, alanine, 2-aminobutyric acid, leucine and methionine, on soil were studied with soil thin layer chromatography. Scanning electron microscopy and X-ray diffraction studies successfully marked the presence of Polyethylene Glycol in the soil. Mobility of amino acid is positively correlated with the concentration of Polyethylene Glycol in the soil. The effect of polymer on soil-amino acid interaction could be applied as a new reference for polymer-improved soil engineering. [ABSTRACT FROM AUTHOR]

Davidia involucrata is a woody perennial and the only living species in the Genus Davidia. It is native to southern China where it holds cultural and scientific importance. However, D. involucrata is now an endangered species and its natural range includes low pH soils which are increasingly impacted by acid rain, nitrogen deposition and imbalanced nutrient cycling. The combination of these stresses also poses the additional risk of aluminum (Al) toxicity. Since the responses of D. involucrata to low pH and aluminum toxicity have not been investigated previously, a hydroponic experiment was conducted to examine the growth of one year old D. involucrata saplings after 50 d growth in a range of pH and Al conditions. Plant biomass, morphology, antioxidant enzyme activity, mineral concentrations and plant ecological strategy were compared at pH 5.8 and pH 4.0 without added Al (AlCl3) and in 0.1, 0.2 and 0.5 mM Al at pH 4.0. Our results showed that compared with pH 5.8, pH 4.0 (without added Al) not only inhibited root and shoot growth but also limited accumulation of nitrogen (N) and phosphorus (P) in leaves of D. involucrate. However, low Al concentrations (0.1 and 0.2 mM Al) at pH 4.0 partially restored the aboveground growth and leaf N concentrations, suggesting an alleviation of H+ toxicity by low Al concentrations. Compared with low Al concentrations, 0.5 mM Al treatment decreased plant growth and concentrations of N, P, and magnesium (Mg) in the leaves, which demonstrated the toxicity of high Al concentration. The results based on plant ecological strategy showed that D. involucrate decreased the competitiveness and favored its stress tolerance as pH changed from 5.8 to 4.0. Meanwhile, the competitiveness and stress tolerance of D. involucrata increased and decreased at low Al concentrations, respectively, and decreased and increased at high Al concentration, respectively. These trade-offs in ecological strategy were consistent with the responses of growth and antioxidant enzyme activity, reflecting a sensitive adaptation of D. involucrata to acid and Al stresses, which may aid in sustaining population dynamics. These findings are meaningful for understanding the population dynamics of D. involucrata in response to aluminum toxicity in acid soils. [ABSTRACT FROM AUTHOR]

Selenium (Se) is a crucial micronutrient for human health. Plants are the primary source of Se for humans. Selenium in the soil serves as the primary source of Se for plants. The soil contains high total Se content in large areas in Guangxi, China. However, the available Se is low, hindering Se uptake by plants. Microorganisms play a pivotal role in the activation of Se in the soil, thereby enhancing its uptake by plants. In this study, selenobacteria were isolated from Se-rich soils in Guangxi. Then two selenobacteria strains, YLB1-6 and YLB2-1, representing the highest (30,000 mg/mL) and lowest (10,000 mg/mL) Se tolerance levels among the Se-tolerant bacteria, were selected for subsequent analysis. Although the two selenobacteria exhibited distinct effects, they can significantly transform Se species, resulting in a decrease in the soil residual Se (RES-Se) content while concurrently increasing the available Se (AVA-Se) content. Selenobacteria also enhance the transformation of Se valencies, with a significant increase observed in soluble Se6+ (SOL-Se6+). Additionally, selenobacteria can elevate the pH of acidic soil. Selenobacteria also promote the uptake of Se into plants. After treatment with YLB1-6 and YLB2-1, the Se content in the aboveground part of Chinese flowering cabbage increased by 1.96 times and 1.77 times, respectively, while the Se accumulation in the aboveground part of the plant significantly increased by 104.36% and 81.69%, respectively, compared to the control. Further whole-genome sequencing revealed the genetic difference between the two selenobacteria. Additionally, 46 and 38 candidate genes related to selenium utilization were identified from YLB1-6 and YLB2-1, respectively. This work accelerates our understanding of the potential molecular mechanism of Se biofortification by selenobacteria. It also provides microorganisms and gene targets for improving crop varieties or microorganisms to exploit the rich Se source in soil. [ABSTRACT FROM AUTHOR]

Ludwigia ravenii (G1G2) is a wetland-obligate perennial, endemic to the Atlantic Coastal Plain. The species appears to be relegated to roadside ditches and ruts, and is under review for federal listing. The objectives of this study were to quantitatively assess biotic and abiotic habitat characteristics of extant populations and augment knowledge of the species ecology. Two congeners were selected for comparative analysis: L. alternifolia and L. pilosa. Over two field seasons, data were collected from 108 1 m2 quadrats and variable length transects across the species range. All 17 element occurrences of L. ravenii on record during the 2020--2021 sampling period were visited and 15 (nplots=62) were sampled. Forty-six plots at 14 sites were collectively sampled for the target congeners (L. alternifolia, nplots=27; L. pilosa, nplots=19). Variables assessed included: physical ditch dimensions, aspect, elevation, canopy cover, abiotic and vegetative cover, and edaphic variables (nutrient composition and pH). Data were visualized using NMS and PCA, and analyzed using ANOVA and post-hoc tests. Only PCA showed distinct clustering of quadrats of L. ravenii along soil fertility gradients. Quadrats of L. ravenii exhibited median values compared to congeners in many measured variables, including canopy cover, species richness, and Shannon's diversity index. Quadrats of L. ravenii differed most strongly from congeners by more acidic mean soil pH (4.68±0.05). Although no single species emerged as an ideal indicator, the combination of L. linearis and Kellochloa verrucosa was found highly suggestive of suitable habitat for L. ravenii. [ABSTRACT FROM AUTHOR]

Background: French bean is one of the most precious and highly relished widely grown short duration legume vegetable. This investigation is intended to assess the integrated manner of nutrient management for higher productivity of French bean under acidic soil condition in subtropical humid zone of Nagaland. Methods: The experiment was carried out during three consecutive years (2017-2018, 2018-2019 and 2019-2020) of rabi season on French bean at Horticultural Research Farm, School of Agricultural Sciences and Rural Development, Medziphema, Nagaland University with the combination of eight treatments. The experiment was laid out in randomized block design with three replications using the variety Arka Komal. Result: The pooled results of three years revealed that the highest growth, quality and yield parameters were observed in treatment T3 (75% NPK through inorganic + 25% N through vermicompost) with maximum plant height (35.68 cm), no. of pods per plant (27.77), no. of seeds per pod (7.01), length of pod (13.96 cm), width of pod (10.58 mm), fresh weight of pod (4.22 g), fresh yield (153.61 q ha-1), crude protein content (28.83%) and benefit cost ratio (4.06) of French bean which was found significantly superior over other treatments. [ABSTRACT FROM AUTHOR]

Copyright of Tropical Grasslands / Forrajes Tropicales is the property of International Centre for Tropical Agriculture - CIAT and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aluminum (Al) toxicity and phosphorus (P) deficiency are widely recognized as major constraints to agricultural productivity in acidic soils. Under this scenario, the development of ryegrass plants with enhanced P use efficiency and Al resistance is a promising approach by which to maintain pasture production. In this study, we assessed the contribution of growth traits, P efficiency, organic acid anion (OA) exudation, and the expression of Al-responsive genes in improving tolerance to concurrent low-P and Al stress in ryegrass (Lolium perenne L.). Ryegrass plants were hydroponically grown under optimal (0.1 mM) or low-P (0.01 mM) conditions for 21 days, and further supplied with Al (0 and 0.2 mM) for 3 h, 24 h and 7 days. Accordingly, higher Al accumulation in the roots and lower Al translocation to the shoots were found in ryegrass exposed to both stresses. Aluminum toxicity and P limitation did not change the OA exudation pattern exhibited by roots. However, an improvement in the root growth traits and P accumulation was found, suggesting an enhancement in Al tolerance and P efficiency under combined Al and low-P stress. Al-responsive genes were highly upregulated by Al stress and P limitation, and also closely related to P utilization efficiency. Overall, our results provide evidence of the specific strategies used by ryegrass to co-adapt to multiple stresses in acid soils. [ABSTRACT FROM AUTHOR]

Acid phosphatases belong to the group of enzymes, phosphomonoesterases, which play a major role in the mineralization of soil organic P. Substrate concentration of enzyme is one of the factors that affect the enzyme kinetics. To study the role of substrate concentration on soil enzyme activity in alfisols, twenty-five surface soil samples were collected and assayed for the activity of soil acid phosphatase. The acid phosphatase activity as expressed in terms of µg of 4-nitrophenol released g-1 soil h-1 in these soils varied from 16.9 to 268.4 with a mean value of 58.8 in surface soils. Among them, ten soil samples were selected to study enzyme kinetics with thirteen substrate concentrations under laboratory incubation studies with three replications. Soil acid phosphatase increased with an increase in substrate concentration up to 20mM and almost reached a plateau at a substrate concentration of more than 15mM. The enzyme activity remained almost constant in all the ten alfisols with further increase in substrate concentration, minimal change in enzyme activity was observed. Characteristics of enzyme activities like maximum enzyme reaction velocity (Vmax) and Michaelis constant (Km) were determined using the Michaelis-Menten equation similar to those determined in a homogenous system. The maximum reaction velocity of soil acid phosphatase for soils under study were calculated (µg of 4-nitrophenol g-1 soil h-1) and varied from 30.0 to 434.8 and the soils S6, S8, S9 and S10 recorded higher values using Line weaver-Burk plot. The values compared well with Hanes-Wolf transformation 25.5 to 364.7 and the soils S6, S8, S7 and S9 recorded higher values. Under Eadie - Hofstee transformation the values varied from 27.7 to 390.3 and higher values were recorded by S6, S8, S9 and S10. Michaelis constant (Km) of the soil acid phosphatase was calculated using Line weaver-Burk transformation plot, varied from 4.9 to 9.6 mM and the higher values were recorded by S6, S8, S1 and S10. The values compared well with those obtained from Hanes-Wolf 2.6 to 6.8 and soils S6, S8, S4 and S7 recorded higher values. In Eadie-Hofstee plots the values ranged from 3.7 to 7.8 and higher values were found in the soils S6, S8, S10 and S4. It was concluded that the linear transformation of Line-weaver Burk values was superior for estimating Km and Vmax values of enzymes in soil. However significant differences were noticed when Km and Vmax were calculated from the linear transformation of Michaelis plot. [ABSTRACT FROM AUTHOR]

Soil health is seriously threatened by the overuse of chemical fertilizers in agricultural management. Biogas slurry is often seen as an organic fertilizer resource that is rich in nutrients, and its use has the goal of lowering the amount of chemical fertilizers used while preserving crop yields and soil health. However, the application of continuous biogas slurry has not yet been studied for its long-term impact on soil nutrients and microbial communities in a rotation system of annual ryegrass-silage maize (Zea mays). This study aimed to investigate the impacts on the chemical properties and microbial community of farmland soils to which chemical fertilizer (NPK) (225 kg ha−1), biogas slurry (150 t ha−1), and a combination (49.5 t ha−1 biogas slurry + 150 kg ha−1 chemical fertilizer) were applied for five years. The results indicated that compared to the control group, the long-term application of biogas slurry significantly increased the SOC, TN, AP, and AK values by 45.93%, 39.52%, 174.73%, and 161.54%, respectively; it neutralized acidic soil and increased the soil pH. TN, SOC, pH, and AP are all important environmental factors that influence the structural composition of the soil's bacterial and fungal communities. Chemical fertilizer application significantly increased the diversity of the bacterial community. Variation was observed in the composition of soil bacterial and fungal communities among the different treatments. The structure and diversity of soil microbes are affected by different methods of fertilization; the application of biogas slurry not only increases the contents of soil nutrients but also regulates the soil's bacterial and fungal community structures. Therefore, biogas slurry can serve as a sustainable management measure and offers an alternative to the application of chemical fertilizers for sustainable intensification. [ABSTRACT FROM AUTHOR]

Acid-sulphate soils are of major environmental concern in many wetlands. Severe acidification episodes have occurred worldwide because of the oxidation of iron sulphides to sulphuric acid by human activities, and diverse techniques have been set up to determine the presence of acid-sulphate soils. This paper evaluates the usefulness of four common easy-to-apply field survey tests for potential acid-sulphate diagnosis in some Histosols and Entisols in wetlands: incomplete oxidation by fast air-drying, incubation, fast oxidation with hydrogen peroxide, and the indirect determination of sulphide with lead acetate. Samples of 227 surface-organic and underlying mineral soils of poorly drained Histosols and Entisols of the Orinoco river delta plain were tested. Results showed that for highly organic samples the interpretation of results obtained from the acid-sulphate soil tests may be misleading, because they cannot be unambiguously related to the production of sulphuric acid derived from pyrite oxidation. Mineral samples yielded more reliable results. The incomplete oxidation by fast air-drying test did not induce significant acidification either in organic or in mineral samples; the final pH values were dependent on the original pH values. The fast oxidation with hydrogen peroxide test was effective with mineral samples. During the incubation test, the slower rate of pH decrease and the final values obtained with the organic samples suggested retardation in the rate and amount of acid generation by pyrite oxidation because of the concurrent oxygen consumption by organic matter and bacterial activity. The indirect determination of sulphide with lead acetate yielded only qualitative results in organic samples, but worked well in mineral samples, indicating a higher content of pyrite intermediates. Effective estimation of the actual presence and potential for acidification of soil is important, in order to avoid excessive or inappropriate amelioration techniques to prevent acid production. [ABSTRACT FROM AUTHOR]

Farmland soil samples from the northern and southern banks of the Wangbeng section of the Huaihe River Basin, China, were collected and treated with three different low-molecular-weight organic acids (LMWOAs) (malic acid, citric acid, oxalic acid). This study aimed to determine how these acids affect soil phosphorus activation. The results showed that the average activation rate of total phosphorus, inorganic phosphorus, Fe/Al-P and Ca-P in soil samples from the southern bank treated with malic and citric acid was above 162%, except for organic phosphorus, with the highest at 192.04%. The three organic acids displayed significantly greater phosphorus activation in the northern bank soil samples than those of the southern bank. However, the overall average activation rate in the northern bank soils was lower than that of the southern bank. The four factors of phosphorus species, acid species, acid concentration, and treatment time had significant effects on phosphorus activation in the soils from both banks. This study showed that the three organic acids significantly activated inert phosphorus in the soil. Among them, malic acid and citric acid had a stronger effect on activating soil phosphorus and increased the available soil phosphorus utilisation rate. [ABSTRACT FROM AUTHOR]

Discusses academic papers that present biological and chemical perspectives of ecosystem disturbance. Algal growth physiology in eutrophic estuaries; Nutrient availability and colonization in acidic lakes with respect to the importance of chemical buffering; Chemistry and microbiology of abandoned coal and metal mines; Metal cycling and the processes controlling alkalinity generation in acidic impacted lake sediments.

Research on acidic forest soils typically uses unbuffered salt solutions as extractants for exchangeable cations. Our lab uses 1 M NH[SUB4]C1 extractant for exchangeable cations (Ca, K, Mg, and Na) and 1 M KCl for exchangeable aluminum. The resulting high dissolved salt solutions presented chronic analytical problems on flame atomic absorption spectrophotometer (AAS) and direct current plasma spectrometer (DCP). More recently, the analyses completed on a simultaneous, axial inductively coupled plasmaatomic emission spectrometer (ICP-AES) have continued to be problematic. Although ICP manufacturers provide application notes that list some precautions to help minimize the salt effect, such issues are seldom mentioned in published articles and can be misleading when interpreting results. This paper describes various modifications that have been tried to eliminate the effects of high dissolved salts when using ICP. Adjustable parameters such as gas flow rates, sample introduction rates, dilution rates, and accessories were tested. Results of each modification were evaluated by comparing method detection limits, recovery rates, and carry-over values to determine the most effective operating ICP system. For example, a 15 second increase of sample uptake and rinse times for the KC1 method decreased the method detection limit (MDL) by 12%, recovery rate by 12%, and carry-over by 25%. [ABSTRACT FROM AUTHOR]

This paper aims at establishing the influence of acidic and alkaline pore fluids on the swell behaviour of an expansive soil. A series of laboratory one dimensional free swell tests were performed to study the behaviour of soil in acidic and alkaline environment. Three different concentrations of sodium hydroxide and sulphuric acid solutions were used as pore fluids to understand the influence of variable concentrations on the swell behaviour of soil. Results showed that, the swelling of soil that interacted with sodium hydroxide solution initially increased at lower concentration and then decreased with increase in concentration. In contrast, the swelling initially decreased at lower concentration of sulphuric acid and then increased with increase in concentration of solution. The complexity in the swell behaviour of contaminated soil was assessed by thoroughly investigating the mineralogy and microstructure alterations by carrying out X-ray diffraction analysis, Scanning electron microscopy and Energy dispersive analysis of X-ray at the end of interaction. [ABSTRACT FROM AUTHOR]

Copyright of Romanian Journal of Materials / Revista Romana de Materiale is the property of Foundation for Materials Science & Engineering Serban Solacolu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)