Extreme Acid Research Articles

Isolation, identification and characterization of biopotential cyclic lipopeptides from Bacillus subtilis strain JN005 and its antifungal activity against rice pathogen Magnaporthe oryzae

In the present study, the cyclic lipopeptides extracted from Bacillus subtilis strain JN005 showed inhibition activity against the rice phytopathogenic fungus Magnaporthe oryzae. The isolated cyclic lipopeptides tolerated high temperature, extreme acidity, extreme alkalinity and ultraviolet radiation. The growth of the mycelium and conidia of the rice phytopathogenic fungus M. oryzae was abnormal after cyclic lipopeptide treatment. In vitro inoculation revealed that cyclic lipopeptide treatment reduced disease incidence by 17.78 ± 2.72% and 22.22 ± 3.51% in the curative and preventive groups, respectively, controlling rice leaf blast. Whole genome sequencing showed that B. subtilis strain JN005 had a circular chromosome with a length of 4,167,853 bp, an average G + C content of 43.86% and 4294 coding DNA sequences. Six gene clusters were identified based on genome analysis encoding for secondary metabolite synthesis of surfactin, fengycin, bacillibactin, bacillaene, subtilosin and bacilysin. Ultra performance liquid chromatography-quadrupole-time of flight-mass spectrometry and ultra performance liquid chromatography-quadrupole-time of flight-mass/mass spectrometry analyses of cyclic lipopeptides further demonstrated the production of surfactin and fengycin derivatives by B. subtilis strain JN005. This study provides insight into the biocontrol potential of B. subtilis strain JN005 and will facilitate its application for the management of rice blast disease caused by M. oryzae.

Facile fabrication of a low-cost, room-temperature curable superhydrophobic coating with excellent stability

SiO2 based superhydrophobic coating has been widely studied as a promising material to extend the service life of various materials. However, the simple preparation of a robust superhydrophobic coatings with room temperature curing capability at low cost is still a challenge in this field. In this work, the fluorinated SiO2 is made from inexpensive industrial water glass by a simple sol-gel method, and the coating is produced by a two-step brushing process and cured at room temperature. The stability of superhydrophobic coatings was verified by wear resistance, chemical stability, and high temperature resistance. Under the ideal preparation conditions obtained by hydrophobic characterizations, the contact angle can be as high as 158.9°, the slide angle is only 3.2°, and it has outstanding self-cleaning properties. The SiO2-EP superhydrophobic coatings notably possess exceptional wear resistance in both smooth glass and rough cement mortar surfaces. Especially on the glass, it can maintain to be superhydrophobic after being worn 50 cycles with 100 g load and 35 cycles with 200 g load on 600-mesh sandpaper. In addition, it maintains excellent superhydrophobic properties even under high temperatures of 300 °C and extreme acid and alkaline corrosive environments. This offers a broad range of application prospects for the application of superhydrophobic coatings for use on various substrates and in extreme environments.

Prevalence, Clinical and Demographic Characteristics of Helicobacter pylori in Patients Undergoing Esophagogastroduodenoscopy in Specialized Health Centers in Two Departments of the Colombian Coffee Growing Axis

Helicobacter pylori is a Gram-negative, microaerophilic bacterium with the ability to survive in extreme acid environments, with pH below 4.0. It is estimated that more than half of the world’s population is infected with this bacterium. Objective: To determine the prevalence, clinical and demographic characteristics of Helicobacter pylori infection in patients undergoing esophagogastroduodenoscopy in two specialized centers of the Coffee Growing Axis in Pereira and Manizales from February to October 2018. Method: Cross-sectional descriptive observational study in which the proportion of positivity to Helicobacter pylori in a period of time was determined. Results: The study included 94 patients; the prevalence of positivity to Helicobacter pylori was 86.1% (81/94), 56 (59.5%) of which were diagnosed by culture and 52 (55.3%) by histology. In the histological study, of the 24 (25.5%) subjects who presented precursor lesions of malignancy, 9 (9.5%) were positive for Helicobacter pylori, while in the 70 subjects (74.5%) without precursor lesions of malignancy, 43 (45.7%) were positive. The significant variables for Helicobacter pylori infection were: Histological response for precursor lesions of malignancy: OR of 0.3808 (95% CI: 0.1408-0.9907) p=0.04 and epigastric pain: OR 0.09489 (95% CI: 0.01928-0.3637) p=0.001. Conclusion: The frequency of Helicobacter pylori infection in the Departments of Risaralda and Caldas is high, and does not discriminate against gender, age, race or origin of the study subjects; Epigastric pain continues to be the most relevant symptom in the diagnosis of Helicobacter pylori infection and the combination of diagnostic tests improves the diagnosis of Helicobacter pylori infection.

Synthesis of Visible Light Excitable Carbon Dot Phosphor-Al2 O3 Hybrids for Anti-Counterfeiting and Information Encryption.

The preparation of room temperature phosphorescent carbon dots still faces great challenges, especially in the case of carbon dots endowed of visible-light excitable room temperature phosphorescence (RTP). To date, a limited number of substrates have been exploited to synthesize room temperature phosphorescent carbon dots, and most of them can emit RTP only in solid state. Here, the synthesis of a composite obtained from the calcination of green carbon dots (g-CDs) blended with aluminum hydroxide (Al(OH)3 ) is reported. The resultant hybrid material g-CDs@Al2 O3 exhibits blue fluorescence and green RTP emissions in an on/off switch process at 365nm. Notably, this composite manifests strong resistance to extreme acid and basic conditions up to 30 days of treatment. The dense structure of Al2 O3 formed by calcination contributes to the phosphorescent emission of g-CDs. Surprisingly, g-CDs@Al2 O3 can also emit yellow RTP under irradiation with white light. The multicolor emissions can be employed for anti-counterfeiting and information encryption. This work provides a straightforward approach to produce room temperature phosphorescent carbon dots for a wide range of applications.

Properties of sandy soil and allelochemical compounds of heath forest in Rantau Abang, Terengganu, Malaysia: Implication for ecological sustainability and biodiversity conservation

Kerangas or heath forests are found on podzolised siliceous sands (spodosols), where gradually decomposing organic matter occurs on the soil’s surface. Changes in the extent of podzol development, soil consistency, and poor nutrient contents signify the unique properties of sandy soil in the heath forest at Rantau Abang, Terengganu, Malaysia. Unfortunately, the sandy soil’s chemical and physical properties are in critical condition due to human activities such as cutting and burning, impacting the sustainability of this ecosystem and its ground cover of shrubs, sparse grass and sedge. Therefore, it is crucial to study the properties of sandy soils in heath forests before their extinction. This analyzed the physical and chemical attributes of heath forest sandy soils regarding heavy metal toxicity, pH, concentrations of carbon, nitrogen, available phosphorus, cation exchange capacity (CEC), allelochemical compounds, total phenolic content in the soil, soil colour, and soil texture. The solid was found to be nutrient-deprived due to its extreme acidity and toxicity. The results showed that allelochemical matters were higher in plants but not in the soil attributes and the water bodies, along with a highly active response in young plant tissues due to their sources of phenolic content. Remarkably, the overall phenolic content was observed to be considerably high in the semi-mature phase of vegetation.

PH-shifting alters textural, thermal, and microstructural properties of mung bean starch-flaxseed protein composite gels.

The objective of this study was to investigate the effect of pH-shifting on the textural and microstructural properties of mung bean starch (MBS)-flaxseed protein (FP) composite gels. Results showed that different pH-shifting treatments caused changes in hydrogen bond interactions and secondary structures in composite gels, leading to the formation of loose or compact gel networks. The pH2-shifting modified protein and starch molecules with shorter chains tended to form smaller intermolecular aggregates, resulting in the formation of a looser gel network. For pH 12-shifting treatment, conformational change of FP caused the unfolding of protein and the exposure of more hydrophobic groups, which enhanced the hydrogen bond and hydrophobic interactions between polymers, contributing to the formation of a compact gel network. Furthermore, pH 12-shifting improved the water-holding capacity (WHC), storage modulus, and strength of gels, while pH2-treated gels exhibited lower WHC, hardness, and gumminess due to the degradation of MBS and denaturation of FP caused by extreme acid condition. These findings suggest that pH-shifting can alter the gel properties of bi-polymeric starch-protein composite systems by affecting the secondary structures of proteins and the hydrogen bonding between the polymers, and provide a promising way for a wide application of FP in soft gel-type food production.

Extreme acidity in a cynipid gall: a potential new defensive strategy against natural enemies.

The morphology of insect-induced galls contributes to defences of the gall-inducing insect species against its natural enemies. In terms of gall chemistry, the only defensive compounds thus far identified in galls are tannins that accumulate in many galls, preventing damage by herbivores. Intrigued by the fruit-like appearance of the translucent oak gall (TOG; Amphibolips nubilipennis, Cynipidae, Hymenoptera) induced on red oak (Quercus rubra), we hypothesized that its chemical composition may deviate from other galls. We found that the pH of the gall is between 2 and 3, making it among the lowest pH levels found in plant tissues. We examined the organic acid content of TOG and compared it to fruits and other galls using high-performance liquid chromatography and gas chromatography-mass spectrometry. Malic acid, an acid with particularly high abundance in apples, represents 66% of the organic acid detected in TOGs. The concentration of malic acid was two times higher than in other galls and in apples. Gall histology showed that the acid-containing cells were enlarged and vacuolized just like fruits mesocarp cells. Accumulation of organic acid in gall tissues is convergent with fruit morphology and may constitute a new defensive strategy against predators and parasitoids.

Exploring the Extreme Acid Tolerance of a Dynamic Protein Nanocage.

Encapsulins are microbial protein nanocages capable of efficient self-assembly and cargo enzyme encapsulation. Due to their favorable properties, including high thermostability, protease resistance, and robust heterologous expression, encapsulins have become popular bioengineering tools for applications in medicine, catalysis, and nanotechnology. Resistance against physicochemical extremes like high temperature and low pH is a highly desirable feature for many biotechnological applications. However, no systematic search for acid-stable encapsulins has been carried out, while the influence of pH on encapsulin shells has so far not been thoroughly explored. Here, we report on a newly identified encapsulin nanocage from the acid-tolerant bacterium Acidipropionibacterium acidipropionici. Using transmission electron microscopy, dynamic light scattering, and proteolytic assays, we demonstrate its extreme acid tolerance and resilience against proteases. We structurally characterize the novel nanocage using cryo-electron microscopy, revealing a dynamic five-fold pore that displays distinct "closed" and "open" states at neutral pH but only a singular "closed" state under strongly acidic conditions. Further, the "open" state exhibits the largest pore in an encapsulin shell reported to date. Non-native protein encapsulation capabilities are demonstrated, and the influence of external pH on internalized cargo is explored. Our results expand the biotechnological application range of encapsulin nanocages toward potential uses under strongly acidic conditions and highlight pH-responsive encapsulin pore dynamics.

Cellulose-Based Fluorescent Material for Extreme pH Sensing and Smart Printing Applications.

Environment-responsive fluorescence materials are being widely investigated for instrument-free determination of various environmental factors. However, developing an eco-friendly cellulose-based fluorescent pH sensor for sensing extreme acidity and alkalinity is still challenging. Herein, a highly fluorescent and multifunctional material is developed from biopolymer-based cellulose acetate. A biopolymer-based structure containing responsive functional groups such as -C═O and -NH is constructed by chemically bonding 5-amino-2,3-dihydrophthalazine-1,4-dione (luminol) onto cellulose acetate using 4,4'-diphenylmethane diisocyanate (MDI) as a cross-linking agent. The prepared material (Lum-MDI-CA) is characterized by UV-vis, Fourier transform infrared, 1H NMR, 13C NMR spectroscopies, and fluorescence techniques. The material exhibits excellent aqua blue fluorescence and demonstrates extreme pH sensing applications. Interesting results are further revealed after adding a pH-unresponsive dye such as MTPP as the reference to develop the ratiometric method. The ratiometric system clearly differentiates the extreme acidic pH 1 from pH 2 and extreme alkaline pH 12, 13, and 14 by visual and fluorescence color change response under a narrow pH range. In addition, the material is fabricated into transparent flexible fluorescent films which demonstrate an outstanding UV shielding, security printing, and haze properties for smart food packaging and printing applications.

Quantitative systems pharmacology (QSP) analysis predicts that olipudase alfa treatment of patients with extreme acid sphingomyelinase deficiencies can result in meaningful debulking of visceral tissue sphingomyelin

Quantitative systems pharmacology (QSP) analysis predicts that olipudase alfa treatment of patients with extreme acid sphingomyelinase deficiencies can result in meaningful debulking of visceral tissue sphingomyelin

The Combination of Dolomite and Hydrated Lime with Different Compositions in Sulfuric Acid Soil for Fish Culture Ponds

Highlight Research Sulfuric acid soil causes extreme acidity of the water (pH<3) and is unsuitable for fish culture Well management for sulfuric acid soil reduce the high risk of soil and water acidity The use of an appropriate combination of different liming is better than the single material to solve the very low pH Combination of dolomite and hydrated lime increased the pH and alkalinity Abstract The application of liming material should consider the amount and quality of chemicals related to cost expenditure and target of expected soil properties since it is usually done with an incorrect number’s estimation and expected soil-water quality which produces unsuccessful results. This study aimed to analyze the effect of different percentages from each combination of dolomite and hydrated lime (DH); DH1 (75:25), DH2 (50:50), and DH3 (25:75), which used five replications to the soil and water quality. The soil samples were taken from the earthen pond of semi-intensive tilapia fish (Oreochromis niloticus) culture in Lat Bua Luang, Rangsit, Thailand, placed into 50 plastic pots (volume = 1.5 L), and mixed with lime of different compositions. Based on the results, the mixture of dolomite and hydrated lime (DH) increased the soil and water pH into the desirable ranges (7.4-8.6). The alkalinity of DH treatments was not higher than that of the single dolomite (DA) or hydrated lime (HA). However, the value was still sufficient (>75 mg/L as CaCO3) to buffer water quality changes. Several depletions of the toxic materials (total aluminum, iron, and manganese) caused by sulfuric acid (FeS2) had been observed in combination treatment, especially in DH1. On the contrary, the essential base cations, calcium, and magnesium increased beyond the single treatment, either dolomite (DA) or hydrated lime (HA). A combination of dolomite and hydrated lime (DH1) as an alternative treatment to remedy aquaculture ponds in acid-containing soil is suggested in terms of efficiency and possible cost-effectiveness.

Multishell Colloidosome Platform with Sequential Gastrointestinal Resistance for On-Demand Probiotic Delivery.

Probiotic-based oral therapy can potentially prevent and treat diseases by regulating the balance of intestinal flora. However, significant loss of viability and bioactivity of probiotics before reaching the colon results in low delivery efficiency and therapeutic effects, which limits their clinical applications. Here, this work proposes a multishell colloidosome (MSC) platform with sequential gastrointestinal resistance for on-demand probiotic delivery based on biomimetic mineralization and microfluidic technology. Notably, the viability of the decorated probiotics increases 280-fold compared to that of free bacteria during preservation. Because of the sequential gastrointestinal resistance of MSC, encapsulated probiotics exhibit high viability (61%) under continuous exposure to extreme acidity, bile salt erosion, and enzymatic action, whereas free bacteria have a viability of 0%. Moreover, in vitro and in vivo studies reveal that MSC mainly releases probiotics in the colon and improves colonic colonization by probiotics to maintain the integrity of the intestinal barrier and regulate the balance of intestinal flora. Consequently, MSC significantly improves the therapeutic effect on colitis in mice. The MSC platform provides a promising delivery strategy to enhance the efficacy of orally administered probiotics.

Convergent Community Assembly among Globally Separated Acidic Cave Biofilms.

Acidophilic bacteria and archaea inhabit extreme geochemical "islands" that can tell us when and how geographic barriers affect the biogeography of microorganisms. Here, we describe microbial communities from extremely acidic (pH 0 to 1) biofilms, known as snottites, from hydrogen sulfide-rich caves. Given the extreme acidity and subsurface location of these biofilms, and in light of earlier work showing strong geographic patterns among snottite Acidithiobacillus populations, we investigated their structure and diversity in order to understand how geography might impact community assembly. We used 16S rRNA gene cloning and fluorescence in situ hybridization (FISH) to investigate 26 snottite samples from four sulfidic caves in Italy and Mexico. All samples had very low biodiversity and were dominated by sulfur-oxidizing bacteria in the genus Acidithiobacillus. Ferroplasma and other archaea in the Thermoplasmatales ranged from 0 to 50% of total cells, and relatives of the bacterial genera Acidimicrobium and Ferrimicrobium were up to 15% of total cells. Rare phylotypes included Sulfobacillus spp. and members of the phyla "Candidatus Dependentiae" and "Candidatus Saccharibacteria" (formerly TM6 and TM7). Although the same genera of acidophiles occurred in snottites on separate continents, most members of those genera represent substantially divergent populations, with 16S rRNA genes that are only 95 to 98% similar. Our findings are consistent with a model of community assembly where sulfidic caves are stochastically colonized by microorganisms from local sources, which are strongly filtered through environmental selection for extreme acid tolerance, and these different colonization histories are maintained by dispersal restrictions within and among caves. IMPORTANCE Microorganisms that are adapted to extremely acidic conditions, known as extreme acidophiles, are catalysts for rock weathering, metal cycling, and mineral formation in naturally acidic environments. They are also important drivers of large-scale industrial processes such as biomining and contaminant remediation. Understanding the factors that govern their ecology and distribution can help us better predict and utilize their activities in natural and engineered systems. However, extremely acidic habitats are unusual in that they are almost always isolated within circumneutral landscapes. So where did their acid-adapted inhabitants come from, and how do new colonists arrive and become established? In this study, we took advantage of a unique natural experiment in Earth's subsurface to show how isolation may have played a role in the colonization history, community assembly, and diversity of highly acidic microbial biofilms.

Morphologic, Radiographic, and Stereomicroscopic Evaluation of Teeth Subjected to High Temperatures: An In vitro Forensic Study

Abstract Background To evaluate morphologic, radiographic, and stereomicroscopic changes of teeth when subjected to specific high temperatures in both direct heat and gradual heat and to compare the changes among two heat groups and also among different types of teeth. Materials and Methods An in vitro study was conducted on 90 healthy extracted human teeth, in which the teeth were divided into two groups. Group 1 (45) was subjected to direct heat and Group 2 (45) was subjected to gradual heat. Group 1 and Group 2 were further subdivided into three subgroups (A) anteriors, (B) premolars, and (C) molars each consisting of 15 teeth. Teeth were subjected to temperatures of 200°C, 400°C, 600°C, 800°C, and 1000°C in a muffle electric furnace. The color changes were noted using the Revised Munsell soil color chart and the radiographic and stereomicroscopic changes were evaluated. The results obtained were subjected to statistical analysis. Results Teeth in direct heat showed more destructive changes at lower temperatures, i.e., 400°C and 600°C when compared to gradual heat where changes are observed at 600°C and 800°C. Among different types of teeth, anteriors and premolars showed more changes when compared to molars. Interpretation and Conclusion It can be concluded that dental evidence may provide clues to solve the mystery in fire investigations as dental structures are the last to be destroyed under extreme conditions, whether temperature, acid, or putrefaction.

The potential use of plant growth promoting Rhizobacteria (PGPR) for Tea Plant Cultivation in Assam: A Review

Plant growth promoting bacteria (PGPR) have been found to be highly beneficial for plants as they help defend against fungal diseases commonly found in soil. They play an important role in plant growth, health and productivity. They increase seedling tolerance to drought, high temperatures, toxic heavy metals, high or low pH and even extreme soil acidity. The use of PGPR has proven to be an environmentally best way to increase the crop yield by facilitating plant growth through either a direct or indirect mechanism. Tea is grown all over the Assam and cultivated in major areas where chemical fertilizers are used. So, the use of PGPR can minimise the application of chemical fertilizer for the production of organic tea. This review highlights the future research works which are needed in many areas of Assam by the use of beneficial strains of PGPR to reduce the use of pesticide for commercial production of organic tea for healthy consumption by the people at large

Different volumes of acetic acid affect the oxygen production of spinach leaves during photosynthesis

The burning of fossil fuels, leading to an increased amount of carbon emissions, is the main cause of acid rain. Acid rain is precipitation that has elevated levels of hydrogen ions due to the formation of carbonic acid. Acid rain affects the process of photosynthesis, which makes the topic valuable to investigate. In the course of chemistry, our group has learned the background information about acid and bases with its properties. With the passion of biology, our group determined to create a lab that consists of both knowledge of chemistry and biology. 
 In 1990, the implementation of the Clean Air Act aimed to limit the amount of carbon emission that causes acid rain with a total annual loss of a hundred 97 million dollars in commercial forest. With such findings, our group utilizes plants to further investigate the relationship between pH value and photosynthesis. In this experiment, our group hypothesized that rain with a lower pH will decrease the rate of photosynthesis, causing less oxygen to be produced in the reaction. Extreme acidity destroys chloroplast structure, decreases chloroplast ATP synthase activity, and reduces photosynthesis and plant growth. However, by conducting an experiment with spinach and utilizing a syringe to collect the amount of oxygen produced during the experiment, we discovered a breakthrough in which a slightly acidic environment can foster photosynthesis until it reaches a pH level less than two.

High luminescent N,S,P co-doped carbon dots for the fluorescence sensing of extreme acidity and folic acid.

Carbon dots are popular luminescent materials because of their excellent fluorescence properties, but the low quantum yield limits their application. Heteroatom doping is a more convenient and popular approach to increase the quantum yield of carbon dots. Here, novel N,S,P heteroatom co-doped carbon dots (N,S,P-CDs) were synthesized by a simple one-step hydrothermal method using m-phenylenediamine, L-cysteine and phosphoric acid as raw materials. The as-prepared N,S,P-CDs showed excellent photoluminescence properties with a fluorescence quantum yield of up to 41%, which greatly encourages their application in fluorescence sensing. The N,S,P-CDs exhibited good fluorescence stability under salt solution, xenon lamp irradiation and ultraviolet lamp irradiation except for a high sensitivity to extreme acidity. The fluorescence intensity of the N,S,P-CDs can be decreased by as much as 85% when the pH of the solution changes from 2.50 to 4.75, that is, a small fluctuation in pH can cause an intense response of the fluorescence of the N,S,P-CDs. Therefore, an excellent fluorescence sensing platform for accurately monitoring the pH of extreme acidity has been constructed. In addition, the N,S,P-CDs can be applied for quantitative detection of folic acid based on the strong quenching effect of folic acid on the fluorescence of the N,S,P-CDs. Good linearity was obtained in the concentration range of 4.85-82.45 μM, with a detection limit of 0.148 μM. The constructed sensing platform was used for the determination of folic acid in actual samples of orange juice, oatmeal and tablets with satisfactory results.

Fabrication of Polyarylate-Based Porous Membranes from Nonsolvent-Induced Phase Separation Process and Related Permeability and Filterability Characterizations

The stability demand of polymeric membrane separation systems used in harsh environments, including high temperature, high pressure, extreme acid, and high salinity, makes the role of polyarylate (PAR) porous membranes more and more crucial. Herein, the PAR ultrafiltration membrane is fabricated from the nonsolvent-induced phase separation (NIPS) method in a simple, high-efficiency way. In order to study the evolution mechanism of cross-sectional pore morphologies during the NIPS process, different coagulation conditions, including the PAR concentration in casting solution, the coagulation temperature, and the addition of different hydrophilic additives (PEG400, PEG4000, PEG20000, and PVP), are applied. Next, the morphologies and membrane performances of various PAR membranes are analyzed by scanning electron microscopy, porosity measurement, N2 isotherm adsorption–desorption measurement, water flux measurement, bovine serum albumin (BSA) separation measurement, and mechanical test. Based on these measurements, the formation rule of different pore morphologies in the cross section of PAR membrane was clarified, and the effects of different cross-sectional morphologies on the permeability, filterability, and mechanical properties of the resultant membranes are pointed out. The viscosity effect from a higher PAR concentration and a higher hydrophilic additive concentration in a casting solution can delay the formation of the outer layer and limit the nucleation growth process of the nonsolvent, then allowing the formation of near-surface sponge-like pores and fewer inner macropores. Moreover, not only the increase of the bath temperature but also the strengthening hydrophilicity of the casting solution can accelerate the double-diffusion rate and the growth process of nuclei, thereby promoting the formation of near-surface finger-like pores and more inner macropores. Combined with the enhancement of membrane hydrophilicity, these pores as channels can accelerate the passage of water through the PAR membrane. For the PAR16–PVP10-30 membrane, not only a 120 L·m–2·h–1·bar–1 of water flux but also a close to 100% of BSA rejection ratio is obtained. Although the formation of near-surface sponge-like pores and fewer inner macropores deteriorate the membrane’s permeability, the high BSA rejection ratio and the improved mechanical property can be maintained. Finally, the optimization component of the casting solution for fabricating a PAR ultrafiltration membrane with enough permeability, high selectivity, and suitable mechanical property adds 10 wt % PVP in the solution of 16 wt % PAR, ensuring the solid hydrophilic effect and moderate viscosity effect.

Soil Acidification in Nutrient-Enriched Soils Reduces the Growth, Nutrient Concentrations, and Nitrogen-Use Efficiencies of Vachellia sieberiana (DC.) Kyal. & Boatwr Saplings.

Nitrogen (N) and phosphorus (P) nutrient enrichment is important for grasslands. This study aimed to determine how soils enriched with N and P influenced soil concentration correlations and affected the growth kinetics, mineral nutrition, and nitrogen-use efficiencies of Vachellia sieberiana grown in a greenhouse experiment. The soils used as the growth substrate were analysed and showed extreme acidity (low soil pH, 3.9). Nitrogen-enriched soils were more acidic than P-enriched soils. Exchangeable acidity was strongly negatively correlated with an increase in soil pH, with soil pH between 3.9 and 4.1 units showing the strongest decline. Plant saplings showed increased root biomass, shoot biomass, total biomass, and plant N and P concentrations when grown in soils with high soil P concentrations. Extreme soil acidification in N-enriched soil was one of the main factors causing P unavailability, decreasing sapling growth. Extreme soil acidification increased concentrations of toxic heavy metals, such as Al which may be alleviated by adding lime to the extremely acidic soils. Research implications suggest that soil pH is an important chemical property of the soil and plays a significant role in legume plant growth. Legume species that are unable to tolerate acidic soils may acquire different strategies for growth and functioning.

Problems, Management, and Prospects of Acid Sulphate Soils in the Ganges Delta

Soil is a finite natural resource and is indispensable for human civilization because it is the medium for food production for the biosphere. Continued soil degradation is a forerunner of catastrophe for the living world. The protection of healthy soils and the restoration of problem soils are strongly needed in the current agricultural scenario as competition for urbanization and other human needs for land resources limits the scope for the further availability of land for agriculture. Naturally occurring degraded soils, such as acid sulphate soils, can be restored with scientific interventions and advanced management strategies. The Ganges Delta is a densely populated region, where the inhabitants’ major livelihood is agriculture. Soil acidity and salinity restrict crop performance in this coastal region, particularly the acid sulphate soils (ASSs) posing a risk to agriculture. ASSs are developed from land-use changes from mangrove forest to agricultural land in this region. There is no systematic study on these soil types covering Bangladesh and India. This paper unfolds several aspects related to the characteristics, problems, and detailed management strategies of ASSs relevant to the Gangetic Delta region where these soils continue to be used for intensive agriculture to meet the livelihood needs. Crop yields are very poor in the unmanaged ASSs due to a very low soil pH (<3.5), hampering the growth and development of crops due to nutrient deficiencies and/or toxicities, coupled with soil salinity. There is toxicity of water-soluble Fe, Al, and Mn. The phosphorus nutrition of crops in these soils is affected owing to a high soil P fixation capacity. A deficiency of micronutrients, such as Zn and Cu, was also observed; however, K availability is variable in the soil. The soil acidity is a general problem throughout the soil profile; however, extreme acidity (pH < 3.5) in particular soil horizons is a typical soil characteristic, which creates problems for its efficient management. Specific operations, such as the selective use of soil layers with good properties for crop root growth, major and minor nutrient applications, and soil amendments, including green manuring, application of biofertilizers, and soil microbes, are gradually improving the properties of these soils and bringing back the potential for good crop production. Scientific water/drainage management is needed to gain an agronomic advantage. Evidence of increased crop yields in these soils observed from green manuring, lime, basic slag, and rock phosphate application are presented.