The necessity to saline and sodic waters is sometimes used for irrigating agricultural activities under certain circumstances, but it is important to note that the use of these waters comes with specific consideration...The necessity to saline and sodic waters is sometimes used for irrigating agricultural activities under certain circumstances, but it is important to note that the use of these waters comes with specific considerations and limitations. One way to decrease undesirable effects of sodic waters on the physical and chemical properties of soils is to apply organic and chemical amendments within the soil. This study aimed to assess the effectiveness of saline water on soil acidity, alkalinity and nutrients leaching in sandy loamy soil at Bella flower farm, in Rwamagana District, Rwanda. The water used was from the Muhazi Lake which is classified as Class I (Saline water quality). Column leaching experiments using treated soils were then conducted under saturated conditions. The soil under experimental was first analyzed for its textural classification, soil properties and is classified as sandy loamy soil. The t-test was taken at 1%, 5% and 10% levels of statistical significance compared to control soil. The results indicated that the application of saline water to soils caused an increase in some soil nutrients like increase of Phosphorus (P), Potassium (K<sup>+</sup>), Magnesium (Mg2<sup>+</sup>), Sulphur (S), CN ratio and Sodium (Na<sup>+</sup>) and decreased soil texture, physical and chemical properties and remained soil nutrients. Consequently, the intensive addition of saline water leachates to soil in PVC pipes led to decreased of soil EC through leaching and a raiser Soluble Sodium Percentage (SSP). The rate of saline water application affected the increase accumulation of SAR and Na% in the top soil layers. The study indicated that saline water is an inefficient amendment for sandy soil with saline water irrigation. The study recommends further studies with similar topic with saline water irrigation, as it accentuated the alkalinity levels.展开更多
The surfaces of red soils have an apparent amphotenc character, carrying titratable acidity and titratable alkalinity simultaneously. The titratable acidity arises from deprotonation of hydroxyl groups of hydrous oxid...The surfaces of red soils have an apparent amphotenc character, carrying titratable acidity and titratable alkalinity simultaneously. The titratable acidity arises from deprotonation of hydroxyl groups of hydrous oxide-type surfaces and dissociation of weak-acid functional groups of soil organic matter, while the titratable alkalinity is derived from release of hydroxyl groups of hydrous oxide-type surfaces. The titratable acidity and titratable alkalinity mainly depended on the composition and content of iron and aluminum oxides in the soils. The results showed that the titratable acidity and titratable alkalinity were in significantly positive correlation not only with the content of amorphous aluminum oxide(Alo) and iron oxide(Feo) extracted with acid ammonium oxalate solution, free iron ox-ide(Fed) extracted with sodium dithionite-citrate-bicarbonate (DCB) and clays, but also with the zero point of charge (ZPC) of the samples. Organic matter made an important contribution to the titratable acidity. The titratable alkalinity was closely correlated with the amount of fluoride ions adsorbed. The titratable acidity and titratable alkalinity of red soils were influenced by parent materials, being in the order of red soil derived from basalt > that from tuff > that from granite. The titratable acidity and titratable alkalinity were closely related with origination of the variable charges of red soils, and to a certain extent were responsible for variable negative and positive charges of the soils.展开更多
Pyrrolizidine alkaloids(PAs)and their N-oxides(PANOs)are phytotoxins produced by various plant species and have been emerged as environmental pollutants.The sorption/desorption behaviors of PAs/PANOs in soil are cruci...Pyrrolizidine alkaloids(PAs)and their N-oxides(PANOs)are phytotoxins produced by various plant species and have been emerged as environmental pollutants.The sorption/desorption behaviors of PAs/PANOs in soil are crucial due to the horizontal transfer of these natural products from PA-producing plants to soil and subsequently absorbed by plant roots.This study firstly investigated the sorption/desorption behaviors of PAs/PANOs in tea plantation soils with distinct characteristics.Sorption amounts for seneciphylline(Sp)and seneciphylline-N-oxide(SpNO)in three acidic soils ranged from 2.9 to 5.9μg/g and 1.7 to 2.8μg/g,respectively.Desorption percentages for Sp and SpNO were from 22.2%to 30.5%and 36.1%to 43.9%.In the mixed PAs/PANOs systems,stronger sorption of PAs over PANOs was occurred in tested soils.Additionally,the Freundlich models more precisely described the sorption/desorption isotherms.Cation exchange capacity,sand content and total nitrogen were identified as major influencing factors by linear regression models.Overall,the soils exhibiting higher sorption capacities for compounds with greater hydrophobicity.PANOs were more likely to migrate within soils and be absorbed by tea plants.It contributes to the understanding of environmental fate of PAs/PANOs in tea plantations and provides basic data and clues for the development of PAs/PANOs reduction technology.展开更多
Bentonite is a very useful material for improving soil properties,which enhances the ability of plants to grow and produce in different conditions.The experiment was carried out in an agricultural nursery in one of th...Bentonite is a very useful material for improving soil properties,which enhances the ability of plants to grow and produce in different conditions.The experiment was carried out in an agricultural nursery in one of the areas of the City of Diwaniyah,in a house covered with green netting,with a shade rate of 25%,to study the effect of bentonite and humic acid on the growth and flowering of a Catharanthus roseus L.plant in sandy soil.The experiment included two factors:the first factor was bentonite clay,and the second factor was humic acid.Using a randomized complete block design(R.C.B.D)with three replications,data were analyzed using the analysis of variance(ANOVA)method,and comparison was made according to the least significant difference(L.S.D)test at a probability level of 0.05.The experiment consisted of adding bentonite clay at 0,2,6,and 8 g L-1,humic acid at 0,0.5,1,and 10 g L-1.The results showed that adding bentonite clay and humic acid to sandy soil can have a significant positive effect on the growth and flowering of the Catharanthus roseus plant grown in poor sandy soil conditions.Bentonite,clay and humic acid were added at concentrations of 8 and 10 g L-1,which led to an increase in plant height and number of leaves and leaf area.They reached 30.07,23.84 cm2,76.62,63.42 cm2 for leaf-1 and 24.73,20.22 cm2 for leaf-1,respectively.The results also showed an increase in the content of nitrogen(N),phosphorus(P),and potassium(K)in leaves by 2.27,1.92,1.99%and 1.51,1.22,1.77%.This also led to an increase in chlorophyll pigment and anthocyanin at the highest concentration and gave the highest value.Therefore,adding bentonite and humic acid together gave the highest values in vegetative and chemical characteristics,compared to treatments without addition.展开更多
Prolonged lack of rain and high-temperature lead to soil water deficits,inhibiting cereal crop growth in early ontogenesis and reducing grain quality and yield.Rye(Secale cereale L.)is a key grain crop,particularly in...Prolonged lack of rain and high-temperature lead to soil water deficits,inhibiting cereal crop growth in early ontogenesis and reducing grain quality and yield.Rye(Secale cereale L.)is a key grain crop,particularly in regions where wheat cultivation is challenging or unfeasible.To clarify its drought adaptation mechanisms,we analyzed the effects of moderate soil drought on growth,hormonal homeostasis,and the dynamics and distribution of free amino acids and phenolic compounds in rye at early vegetative stages and post-recovery.Drought triggered both general and organ-specific changes in endogenous phytohormones.A nonspecific response involved the accumulation of stress hormones abscisic acid(ABA)and salicylic acid(SA),alongside the suppression of growth hormones indole-3-acetic acid(IAA)and gibberellins.However,hormone dynamics and localization varied across plant organs.ABA and SA levels significantly increased in shoots of drought-stressed and recovered plants,corresponding with inhibited growth.Prolonged drought further enhanced ABA accumulation in both shoots and roots of recovered plants,while SA levels declined in roots but remained elevated in shoots.Drought also caused a substantial reduction in IAA,particularly in shoots,while gibberellins(GA_(3)+GA_(4))significantly decreased in roots.GA_(3)was predominant in most samples,except in the shoots of 2-day-old control plants.Post-recovery,IAA levels increased but remained below control values,while GA_(4)accumulation in roots led to a rise in total gibberellin levels.In contrast,shoot GA_(3)+GA_(4)levels declined,primarily due to GA_(3)reduction.The dominant free amino acids:aspartic acid,glutamic acid,glycine,alanine,and leucinedecreased significantly,underscoring their key role in stress adaptation.Increased flavonoid accumulation,especially in roots,suggests their involvement in antioxidant defense against oxidative stress.A significant increase in ABA and SA levels,along with a marked reduction in IAA and GA content in stressed rye plants occurred alongside a reduction in free amino acid content,accumulation of phenolic compounds,and an increase in flavonoid levels.These findings indicate distinct adaptation strategies in rye shoots and roots undermoderate soil drought.They provide a foundation for further research on drought resistance mechanisms in cereals and the development of strategies to enhance their adaptive potential.展开更多
The environmental impacts of acid mine drainage(AMD)from open-pit mining are profoundly detrimental,yet knowledge about its effects on paddy soil microbial communities,especially at greater depths,remains limited.In t...The environmental impacts of acid mine drainage(AMD)from open-pit mining are profoundly detrimental,yet knowledge about its effects on paddy soil microbial communities,especially at greater depths,remains limited.In this investigation,we compared soils affected by AMD versus unaffected soil depth profiles in terms of bacterial diversity and community assembly.The profiles in AMD-polluted soils exhibited tight geochemical gradients,characterized by increased acidity,SO_(4)^(2-),NO_(3)^(-),and heavy metal content compared to unpolluted soils.Notably,AMD significantly diminished soil bacterial biodiversity.A depthwise analysis showed distinct microbial stratification,with certain bacteria like Candidatus_Solibacter and Candidatus_Koribacter predominated in polluted soils,while others like Haliangium and Nitrospira were more prevalent in control soils.Interestingly,despite variable soil conditions,predictedmetabolic pathways,particularly those involving carbon,nitrogen,and sulfur,showed relative stability.AMD pollution induced the upregulation of methylcoenzyme M reductase and sulfate reductase genes.Bacterial communities were more responsive to pH and nutrient content rather than heavy metals,with pH and SO_(4)^(2-)being the primary drivers of microbial diversity and distribution.Additionally,pHwas identified as the most significant influence on the predicted methane,sulfur,and nitrogen metabolism.Furthermore,deterministic processes played a more significant role in community assembly of polluted soils,while heterogeneous selection gained importance with increasing depth in control soils.Additionally,microbial co-occurrences,particularly positive interactions,were more prevalent in the polluted soils with reduced network modularity and keystone taxa.These findings offer insights into sustaining microbial diversity in extreme environments.展开更多
Water scarcity and soil salinization pose significant challenges to agriculture in the West Liaohe Plain,eastern Inner Mongolia,China.Shallow-buried drip irrigation can improve soil water use efficiency to alleviate w...Water scarcity and soil salinization pose significant challenges to agriculture in the West Liaohe Plain,eastern Inner Mongolia,China.Shallow-buried drip irrigation can improve soil water use efficiency to alleviate water shortage in agriculture and the application of lignite humic acid reduces the adverse effects of soil salinization.However,further research is needed to investigate the effects of different application rates of lignite humic acid and humic acid-based combined amendment on soil physicochemical properties,nutrient contents,and crop yield in saline-sodic farmlands under shallow-buried drip irrigation.A two-year field experiment was conducted with control without any amendment(CK),three treatments amended with 3 t/ha(H1),6 t/ha(H2),and 12 t/ha(H3)lignite humic acid,and three application rates with 15 t/ha(T1),22.5 t/ha(T2),and 30 t/ha(T3)lignite humic acid-based combined amendment in 2021 and2022.The results showed that H3 reduced soil bulk density,p H,electrical conductivity,and total alkalinity,while increasing the contents of soil organic matter,total nitrogen,and available potassium in the two-year experiment.Moreover,the maize yield in H3 increased by an average of 35.5%.T2 decreased soil bulk density,p H,total alkalinity,and increased maize yield by 16.2%,compared to the first year.These results suggest that T2 consistently improved both soil quality and crop yield.Correlation analyses showed that lignite humic acid and its complexes promote maize growth and increase yield by increasing soil organic matter and total nitrogen while reducing soil salinity and total alkalinity.Based on the comprehensive analysis of the field data and the results of the comprehensive evaluation of soil quality,it was determined that the appropriate improvement measures for saline-sodic farmlands under shallow-buried drip irrigation are the application of 12 t/ha of lignite humic acid and 22.5 t/ha of lignite humic acid-based combined amendment.This study demonstrates the effectiveness of lignite humic acid and its combined amendment in mitigating the constraints of saline-sodic farmlands and enhancing crop yields,providing a sustainable solution for improving saline-sodic farmlands in the West Liaohe Plain.展开更多
A pot experiment was catried out to study alleviation of soil acidity and Al toxicity by applying analkaline-stabilised sewage sludge product (biosolids) to an acid clay sandy loam (pH 5.7) and a strongly acidsandy lo...A pot experiment was catried out to study alleviation of soil acidity and Al toxicity by applying analkaline-stabilised sewage sludge product (biosolids) to an acid clay sandy loam (pH 5.7) and a strongly acidsandy loam (pH 4.5). Barley (Hondeum vulgare L. cv. Forrester) was used as a test crop and was grownin the sewage sludge-amended (33.5 t sludge DM ha-1) and unamended soils. The results showed that thealka1ine biosloids increased soil pH from 5.7 to 6.9 for the clay sandy loam and from 4.5 to 6.0 for the sandyloam. The sludge product decreased KCl-extractable Al from 0.1 to 0.0 cmol kg-1 for the former soil andfrom 4.0 to 0.1 cmol kg-1 for the latter soil. As a result, barley plants grew much better and grain yieldincreased greatly in the amended treatments compared with the unamended controls. These observationsindicate that alkaline-stabilised biosolids can be used as a liming material for remedying Al phytotoxicity instrongly acid soils by increasing soil pH and lowering Al bioavailability.展开更多
In this decade,coal fly ash(CFA)is considered a potential secondary source of rare earth elements(REEs).However,most REEs in coal fly ash are encapsulated in aluminosilicate glass,making it challenging to recover them...In this decade,coal fly ash(CFA)is considered a potential secondary source of rare earth elements(REEs).However,most REEs in coal fly ash are encapsulated in aluminosilicate glass,making it challenging to recover them through acid leaching.In this study,a sequential alkaline-organic acid leaching was developed for the recovery of REEs from CFA.The effect of alkaline leaching using NaOH solution on the destructive ability of aluminosilicate glass,as well as the mineralogy and morphology changes of the resulting coal fly ash,was first studied.Furthermore,the effectiveness of alkaline leaching on the recovery ability of REEs through organic acid leaching was evaluated.The results show that the maximum leaching efficiency for Si and Al,which was obtained at the optimum alkaline leaching conditions,namely NaOH concentration of 10 mol/L,reaction temperature of 65℃,liquid/solid(L/S)ratio of 10 mL/g,and reaction time of 90 min,is 28%and 32%,respectively.The digestion reaction with NaOH lixiviants also causes coal fly ash to become more porous,making it advantageous in the organic acid-leaching process at the REEs recovery stage.The utilization of the desilicated residue produced from the digestion process in acid leaching effectively increases the overall REEs recovery from 32.2%to 77.6%.展开更多
The digestibility of cadmium(Cd)in brown rice is directly related to amino acid metabolism in rice and human health.In our field study,three kinds of alkaline calcium-rich soil inorganic amendments(SIAs)at three dosag...The digestibility of cadmium(Cd)in brown rice is directly related to amino acid metabolism in rice and human health.In our field study,three kinds of alkaline calcium-rich soil inorganic amendments(SIAs)at three dosages were applied to produce safe rice and improve the quality of rice in Cd-contaminated paddy.With the increased application of SIA,Cd content in iron plaque on rice root significantly increased,the transfer of Cd from rice root to grain significantly decreased,and then Cd content in brown rice decreased synchronously.The vitro digestibility of Cd in brown rice was estimated by a physiologically based extraction test.Results showed that more than 70%of Cd in brown rice could be digested by simulated gastrointestinal juice.Based on the total and digestible Cd contents in brown rice to evaluate the health risk,the application of 2.25 ton SIA/ha could produce safe rice in acidic slightly Cd-contaminated paddy soils.The amino acids(AAs)in brown rice were determined by high-performance liquid chromatography.The contents of 5 key AAs(KAAs)that actively respond to environmental changes increased significantly with the increased application of SIA.The structural equation model indicated that KAAs could be affected by the Cd translocation capacity from rice root to grain,and consequently altered the ratio of indigestible Cd in brown rice.The formation of indigestible KAAs-Cd complexes by combining KAAs(phenylalanine,leucine,histidine,glutamine,and asparagine)with Cd in brown rice could be considered a potential mechanism for reducing the digestibility of Cd.展开更多
It is imperative to choose some low cost, available and effective ameliorants to correct soil acidity in southern China for sustainable agriculture. The present investigation dealt with the possible role of industrial...It is imperative to choose some low cost, available and effective ameliorants to correct soil acidity in southern China for sustainable agriculture. The present investigation dealt with the possible role of industrial byproducts, i.e., coal fly ash （CFA）, alkaline slag （AS）, red mud （RM） and phosphogypsum （PG） in correcting acidity and aluminum （Al） toxicity of soils under tea plantation using an indoor incubation experiment. Results indicated that CFA, AS and RM increased soil pH, while PG decreased the pHs of an Ultisol and an Alfisol. The increment of soil pH followed the order of RM 〉 AS 〉 CFA. All the industrial byproducts invariably decreased exchangeable Al and hence increased exchangeable Ca, Mg, K and Na and effective cation exchange capacity. RM, AS and lime decreased total soluble Al, exchangeable Al and organically bound Al. Formation and retention of hydroxyl-Al polymers were the principal mechanism through which Al phytotoxicity was alleviated by application of these amendments. In addition, the heavy metal contents in the four industrial byproducts constituted a limited environmental hazard in a short time at the rates normally used in agriculture. Therefore, the short-term use of the byproducts, especially AS and RM, as amendments for soil acidity and AI toxicity in acid soils may be a potential alternative to the traditional use of mined gypsum and lime.展开更多
Extensive acidic soils,which suffer from accelerated soil acidification,are found in southern China.Soil acidity,aluminum toxicity,and nutrient deficiencies severely limited crop productivity in acidic soils.It has be...Extensive acidic soils,which suffer from accelerated soil acidification,are found in southern China.Soil acidity,aluminum toxicity,and nutrient deficiencies severely limited crop productivity in acidic soils.It has been widely reported that crop residue biochars can ameliorate acidic soils and increase crop productivity.Here,we summarized the positive effects and mechanisms involved in the correction of soil acidity,the alleviation of aluminum toxicity and the increase of soil pH buffering capacity by crop residue biochars.The carbonate,oxygen-containing functional groups and silicates in biochars are the major components responsible for their efficacy in amending acidic soils and resisting soil re-acidification.We conclude that application of crop residue biochars may be a better option than traditional liming to ameliorate acidic soils.Nonetheless,further researches into soil acidification are still required to address some issues that are controversial and poorly understood.展开更多
Strongly acidic soils （pH 〈 5.0） are detrimental to tea （Camellia sinensis） production and quality. Little information exists on the ability of surface amendments to ameliorate subsoil acidity in the tea garden s...Strongly acidic soils （pH 〈 5.0） are detrimental to tea （Camellia sinensis） production and quality. Little information exists on the ability of surface amendments to ameliorate subsoil acidity in the tea garden soils. A 120-d glasshouse column leaching experiment was conducted using commonly available soil ameliorants. Alkaline slag （AS） and organic residues, pig manure （PM） and rapeseed cake （RC） differing in ash alkalinity and C/N ratio were incorporated alone and in combination into the surface （0-15 cm） of soil columns （10 cm internal diameter x 50 cm long） packed with soil from the acidic soil layer （15-30 cm） of an Ultisol （initial pH -- 4.4）. During the 120-d experiment, the soil columns were watered （about 127 mm over 9 applications） according to the long-term mean annual rainfall （1 143 mm） and the leachates were collected and analyzed. At the end of the experiment, soil columns were partitioned into various depths and the chemical properties of soil were measured. The PM with a higher C/N ratio increased subsoil pH, whereas the RC with a lower C/N ratio decreased subsoil pH. However, combined amendments had a greater ability to reduce subsoil acidity than either of the amendments alone. The increases in pH of the subsoil were mainly ascribed to decreased base cation concentrations and the decomposition of organic anions present in dissolved organic carbon （DOC） and immobilization of nitrate that had been leached down from the amended layer. A significant （P 〈 0.05） correlation between alkalinity production （reduced exchangeable acidity - N-cycle alkalinity） and alkalinity balance （net alkalinity production - N-cycle alkalinity） was observed at the end of the experiment. Additionally, combined amendments significantly increased （P ~ 0.05） subsoil cation concentrations and decreased subsoil A1 saturation （P 〈 0.05）. Combined applications of AS with organic amendments to surface soils are effective in reducing subsoil acidity in high-rainfall areas. Further investigations under field conditions and over longer timeframes are needed to fully understand their practical effectiveness in ameliorating acidity of deeper soil layers under naturally occurring leaching regimes.展开更多
Burying a straw layer and applying flue gas desulphurization(FGD)gypsum are effective practices to ameliorate soil salinization or alkalization and to increase crop yield;however,little information exists on the effec...Burying a straw layer and applying flue gas desulphurization(FGD)gypsum are effective practices to ameliorate soil salinization or alkalization and to increase crop yield;however,little information exists on the effects of such integration in saline-alkali soils.A soil column experiment was conducted to investigate the effects of a straw layer plus FGD gypsum on soil salinity and alkalinity.We placed a straw layer(5 cm thick)at a depth of 30 cm and mixed FGD gypsum into the 0–20 cm soil layer at application rates of 7.5,15.0,22.5,and 30.0 t ha^-1,with no straw layer and FGD gypsum as a control(CK).The soil water content in the 0–30 cm soil layer was significantly higher(>7.8%)in the treated soil profiles after infiltration than in the CK,but decreased after evaporation.The electrical conductivity(EC)of the 10–30 cm soil layer was 230.2%and 104.9%higher in the treated soil profiles than in the CK after infiltration and evaporation,respectively,and increased with increasing rates of FGD gypsum application,with Ca^2+and SO4^2-being the main dissolved salts.Compared to those in the CK,the concentrations of Na^+,Cl^-,and HCO3-decreased in the treated soil profiles at depths above 55 cm,but the other soluble ions increased,after infiltration.A similar trend occurred after evaporation for all soluble ions except for HCO3-.The p H and exchangeable sodium percentage in the treated soil profiles were significantly lower than those in the CK over the entire profile,and decreased with increasing FGD gypsum application rates.Therefore,the incorporation of a straw layer plus FGD gypsum can reduce salinity and alkalinity,but the quantity of FGD gypsum should be controlled in saline-alkali soils.展开更多
This investigation was conducted by using alkaline slag and crop straw biochars to reduce acidity of an acidic Ultisol through incubation and pot experiments with lime as a comparison. The soil was amended with differ...This investigation was conducted by using alkaline slag and crop straw biochars to reduce acidity of an acidic Ultisol through incubation and pot experiments with lime as a comparison. The soil was amended with different liming materials: lime(1 g kg-1),alkaline slag(2 and 4 g kg-1), peanut straw biochar(10 and 20 g kg-1), canola straw biochar(10 and 20 g kg-1) and combinations of alkaline slag(2 g kg-1) and biochars(10 g kg-1) in the incubation study. A pot experiment was also conducted to observe the soybean growth responses to the above treatments. The results showed that all the liming materials increased soil p H and decreased soil exchangeable acidity. The higher the rates of alkaline slag, biochars, and alkaline slag combined with biochars, the greater the increase in soil p H and the reduction in soil exchangeable acidity. All the amendments increased the levels of one or more soil exchangeable base cations. The lime treatment increased soil exchangeable Ca2+, the alkaline slag treatment increased exchangeable Ca2+and Mg2+levels, and the biochars and combined applications of alkaline slag with biochars increased soil exchangeable Ca2+, Mg2+and K+and soil available P. The amendments enhanced the uptake of one or more nutrients of N, P, K, Ca and Mg by soybean in the pot experiment. Of the different amendments, the combined application of alkaline slag with crop straw biochars was the best choice for increasing base saturation and reducing soil acidity of the acidic Ultisol. The combined application of alkaline slag with biochars led to the greatest reduction in soil acidity, increased soil Ca, Mg, K and P levels, and enhanced the uptake of Ca, Mg, K and P by soybean plants.展开更多
The sorption of a triazol derivative, 1-(4-chlorophenyl)- 4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)penten-3-ol with a common name of S3307D, on fifteen soils and three H_2O_2-treated soils was investigated. The sorption ...The sorption of a triazol derivative, 1-(4-chlorophenyl)- 4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)penten-3-ol with a common name of S3307D, on fifteen soils and three H_2O_2-treated soils was investigated. The sorption isotherm for each untreated and treated soil was non-linear, and was best fitted to Freundlich sorption equation. Soils containing high amount of clay content or organic matter or both sorbed much higher amounts of the chemical than soils that had low contents of these soil constituents. H_2O_2-treated soils showed considerable sorptive affinity for S3307D. It was concluded that both organic matter and mineral fraction in natural soils contributed to the sorption of the basic compound. Sorption by the H_2O_2 treated soils increased as suspension pH decreased, but all suspension pHs exceeded the pKa of the compound by more than two units. This implies that organic base protonation can occur on surfaces of soil components, and surface acidity (exchangeable acidity ) is important in sorption process of the organic base rather than suspension pH.展开更多
An extremely acidified acid sulfate soil (ASS) was investigated to characterize its soluble and exchangeableacidity. The results showed that soluble acidity of a sample determined by titration with a KOH solutionwas m...An extremely acidified acid sulfate soil (ASS) was investigated to characterize its soluble and exchangeableacidity. The results showed that soluble acidity of a sample determined by titration with a KOH solutionwas much significantly greater than that indicated by pH measured using a PH meter, particularly for theextremely acidic soil samples. This is because the total soluble acidity of the extremely acidic soil sampleswas mainly composed of various soluble Al and Fe species, possibly in forms of Al sulfate complexes (e.g.,AISO4) and ferrous Fe (Fe2+). It is therefore suggested not to use pH alone as an indicator of soluble acidityin ASS, particularly for extremely acidic ASS. It is also likely that AISO4+ actively pericipated in cationexchange reactions. It appears that the possible involvement of this Al sulfate canon in the canon adsorptionhas significant effect on increasing the amount of acidity being adsorbed by the soils.展开更多
The acidity regimes of representative soils on the north slope of the Changbai Mountains were examined through determinations of PH and pCa of the soil paste as well as in-site determinations. For soils under broad-le...The acidity regimes of representative soils on the north slope of the Changbai Mountains were examined through determinations of PH and pCa of the soil paste as well as in-site determinations. For soils under broad-leaf forest or broad-leaf-Korean pine forest, the pH decreased from the litter to lower layers gradually until it did not change or decreased further slightly. For soils under coniferous forest or Ermans birch forest,there was a minimum in pH at a depth of 3～6 cm where the content of humus was high. The pCa increased gradually from the soil surface downward to a constant value. The lime potential (pH-0.5pCa) showed a similar trend as the PH in its distribution. For a given soil, the measured pH value of the thick paste, ranging from 4.5 to 5.5, was lower by about 0.5 units than the value determined by the conventional method with a water to soil ratio of 5:1. The PH determined in site was even lower. It was found that there was a fairly close relationship between soil acidity and the type of vegetation. The pH showed a trend of decreasing from soils under broad-leaf forest through broad-leaf-conifer mixed forest and coniferous forest to Ermans birch forest, and the pCa showed an opposite trend in variation.展开更多
Some Inceptisols representing the Singla catchment area in Karimgaungedistrict of Assam, India, were studied for lime requirement as influenced by the nature of soilacidity. The electrostatically bonded (EB)-H^+ and E...Some Inceptisols representing the Singla catchment area in Karimgaungedistrict of Assam, India, were studied for lime requirement as influenced by the nature of soilacidity. The electrostatically bonded (EB)-H^+ and EB-Al^(3+) acidities constituted 33 and 67percent of exchangeable acidity while EB-H^+, EB-Al^(3+), exchangeable and pH-dependent aciditiescomprised 6, 14, 20 and 80 percent of total potential acidity. The pH-dependent acidity made a majorcontribution towards the total potential acidity (67%～84%). Grand mean of lime requirementdetermined by the laboratory incubation method and estimated by the methods of New Woodruff,Woodruff and Peech as expressed in MgCaCO_3 ha^(-1) was in the order: Woodruff (15.6) > New Woodruff(14.9) > Peech (5.1) > incubation (5.0). Correlations analysis among different forms of acidity andlime requirement methods with selected soil properties showed that pH in three media, namely water,1 mol L^(-1) KC1 and 0.01 mol L^(-1) CaCl_2, had a significant negative correlation with differentforms of acidity and lime requirement methods. Exchangeable Fe and Al showed significant positivecorrelations with EB-Al^(3+) acidity, exchangeable acidity, pH-dependent acidity and total potentialacidity, and also lime requirement methods. Extractable Al showed positive correlations withdifferent forms of acidity except EB-H^+ and EB-Al^(3+) acidities. The lime requirement by differentmethods depended upon the extractable aluminium. Significant positive correlations existed betweenlime requirements and different forms of acidity of the soils except EB-H^+ acidity and incubationmethod. The nature of soil acidity was mostly pH-dependent. Statistically, the Woodruff method didslightly better than the New Woodruff, incubation and Peech methods at estimating lime requirementand hence the Woodruff procedure may be recommended for routine soil testing because of its speedand simplicity.展开更多
Soil aggregate is the basic structural unit of soil,which is the foundation for supporting ecosystem functions,while its composition and stability is significantly affected by the external environment.This study was c...Soil aggregate is the basic structural unit of soil,which is the foundation for supporting ecosystem functions,while its composition and stability is significantly affected by the external environment.This study was conducted to explore the effect of external environment(wetting-drying cycles and acidic conditions)on the soil aggregate distribution and stability and identify the key soil physicochemical factors that affect the soil aggregate stability.The yellow‒brown soil from the Three Gorges Reservoir area(TGRA)was used,and 8 wetting-drying conditions(0,1,2,3,4,5,10 and 15 cycles)were simulated under 4 acidic conditions(pH=3,4,5 and 7).The particle size distribution and soil aggregate stability were determined by wet sieving method,the contribution of environmental factors(acid condition,wetting-drying cycle and their combined action)to the soil aggregate stability was clarified and the key soil physicochemical factors that affect the soil aggregate stability under wetting-drying cycles and acidic conditions were determined by using the Pearson’s correlation analysis,Partial least squares path modeling(PLS‒PM)and multiple linear regression analysis.The results indicate that wetting-drying cycles and acidic conditions have significant effects on the stability of soil aggregates,the soil aggregate stability gradually decreases with increasing number of wetting-drying cycles and it obviously decreases with the increase of acidity.Moreover,the combination of wetting-drying cycles and acidic conditions aggravate the reduction in the soil aggregate stability.The wetting-drying cycles,acidic conditions and their combined effect imposes significant impact on the soil aggregate stability,and the wetting-drying cycles exert the greatest influence.The soil aggregate stability is significantly correlated with the pH,Ca^(2+),Mg^(2+),maximum disintegration index(MDI)and soil bulk density(SBD).The PLS‒PM and multiple linear regression analysis further reveal that the soil aggregate stability is primarily influenced by SBD,Ca^(2+),and MDI.These results offer a scientific basis for understanding the soil aggregate breakdown mechanism and are helpful for clarifying the coupled effect of wetting-drying cycles and acid rain on terrestrial ecosystems in the TGRA.展开更多
文摘The necessity to saline and sodic waters is sometimes used for irrigating agricultural activities under certain circumstances, but it is important to note that the use of these waters comes with specific considerations and limitations. One way to decrease undesirable effects of sodic waters on the physical and chemical properties of soils is to apply organic and chemical amendments within the soil. This study aimed to assess the effectiveness of saline water on soil acidity, alkalinity and nutrients leaching in sandy loamy soil at Bella flower farm, in Rwamagana District, Rwanda. The water used was from the Muhazi Lake which is classified as Class I (Saline water quality). Column leaching experiments using treated soils were then conducted under saturated conditions. The soil under experimental was first analyzed for its textural classification, soil properties and is classified as sandy loamy soil. The t-test was taken at 1%, 5% and 10% levels of statistical significance compared to control soil. The results indicated that the application of saline water to soils caused an increase in some soil nutrients like increase of Phosphorus (P), Potassium (K<sup>+</sup>), Magnesium (Mg2<sup>+</sup>), Sulphur (S), CN ratio and Sodium (Na<sup>+</sup>) and decreased soil texture, physical and chemical properties and remained soil nutrients. Consequently, the intensive addition of saline water leachates to soil in PVC pipes led to decreased of soil EC through leaching and a raiser Soluble Sodium Percentage (SSP). The rate of saline water application affected the increase accumulation of SAR and Na% in the top soil layers. The study indicated that saline water is an inefficient amendment for sandy soil with saline water irrigation. The study recommends further studies with similar topic with saline water irrigation, as it accentuated the alkalinity levels.
基金Project supported by the National Natural Science Foundation of China.
文摘The surfaces of red soils have an apparent amphotenc character, carrying titratable acidity and titratable alkalinity simultaneously. The titratable acidity arises from deprotonation of hydroxyl groups of hydrous oxide-type surfaces and dissociation of weak-acid functional groups of soil organic matter, while the titratable alkalinity is derived from release of hydroxyl groups of hydrous oxide-type surfaces. The titratable acidity and titratable alkalinity mainly depended on the composition and content of iron and aluminum oxides in the soils. The results showed that the titratable acidity and titratable alkalinity were in significantly positive correlation not only with the content of amorphous aluminum oxide(Alo) and iron oxide(Feo) extracted with acid ammonium oxalate solution, free iron ox-ide(Fed) extracted with sodium dithionite-citrate-bicarbonate (DCB) and clays, but also with the zero point of charge (ZPC) of the samples. Organic matter made an important contribution to the titratable acidity. The titratable alkalinity was closely correlated with the amount of fluoride ions adsorbed. The titratable acidity and titratable alkalinity of red soils were influenced by parent materials, being in the order of red soil derived from basalt > that from tuff > that from granite. The titratable acidity and titratable alkalinity were closely related with origination of the variable charges of red soils, and to a certain extent were responsible for variable negative and positive charges of the soils.
基金supported by the earmarked fund for the Modern Agro-Industry Technology Research System (No.CARS-19)the Innovative Research Team in Chinese Academy of Agricultural Sciences (No.CAAS ASTIP-2014-TRICAAS).
文摘Pyrrolizidine alkaloids(PAs)and their N-oxides(PANOs)are phytotoxins produced by various plant species and have been emerged as environmental pollutants.The sorption/desorption behaviors of PAs/PANOs in soil are crucial due to the horizontal transfer of these natural products from PA-producing plants to soil and subsequently absorbed by plant roots.This study firstly investigated the sorption/desorption behaviors of PAs/PANOs in tea plantation soils with distinct characteristics.Sorption amounts for seneciphylline(Sp)and seneciphylline-N-oxide(SpNO)in three acidic soils ranged from 2.9 to 5.9μg/g and 1.7 to 2.8μg/g,respectively.Desorption percentages for Sp and SpNO were from 22.2%to 30.5%and 36.1%to 43.9%.In the mixed PAs/PANOs systems,stronger sorption of PAs over PANOs was occurred in tested soils.Additionally,the Freundlich models more precisely described the sorption/desorption isotherms.Cation exchange capacity,sand content and total nitrogen were identified as major influencing factors by linear regression models.Overall,the soils exhibiting higher sorption capacities for compounds with greater hydrophobicity.PANOs were more likely to migrate within soils and be absorbed by tea plants.It contributes to the understanding of environmental fate of PAs/PANOs in tea plantations and provides basic data and clues for the development of PAs/PANOs reduction technology.
文摘Bentonite is a very useful material for improving soil properties,which enhances the ability of plants to grow and produce in different conditions.The experiment was carried out in an agricultural nursery in one of the areas of the City of Diwaniyah,in a house covered with green netting,with a shade rate of 25%,to study the effect of bentonite and humic acid on the growth and flowering of a Catharanthus roseus L.plant in sandy soil.The experiment included two factors:the first factor was bentonite clay,and the second factor was humic acid.Using a randomized complete block design(R.C.B.D)with three replications,data were analyzed using the analysis of variance(ANOVA)method,and comparison was made according to the least significant difference(L.S.D)test at a probability level of 0.05.The experiment consisted of adding bentonite clay at 0,2,6,and 8 g L-1,humic acid at 0,0.5,1,and 10 g L-1.The results showed that adding bentonite clay and humic acid to sandy soil can have a significant positive effect on the growth and flowering of the Catharanthus roseus plant grown in poor sandy soil conditions.Bentonite,clay and humic acid were added at concentrations of 8 and 10 g L-1,which led to an increase in plant height and number of leaves and leaf area.They reached 30.07,23.84 cm2,76.62,63.42 cm2 for leaf-1 and 24.73,20.22 cm2 for leaf-1,respectively.The results also showed an increase in the content of nitrogen(N),phosphorus(P),and potassium(K)in leaves by 2.27,1.92,1.99%and 1.51,1.22,1.77%.This also led to an increase in chlorophyll pigment and anthocyanin at the highest concentration and gave the highest value.Therefore,adding bentonite and humic acid together gave the highest values in vegetative and chemical characteristics,compared to treatments without addition.
基金This publication presents findings from research conducted under Project No.III-99-24.489Natural Growth Regulators in the Induction of Resistance of Cereal Plants to HeavyMetals(2024-2028)funded by the NationalAcademy of Sciences of Ukraine.
文摘Prolonged lack of rain and high-temperature lead to soil water deficits,inhibiting cereal crop growth in early ontogenesis and reducing grain quality and yield.Rye(Secale cereale L.)is a key grain crop,particularly in regions where wheat cultivation is challenging or unfeasible.To clarify its drought adaptation mechanisms,we analyzed the effects of moderate soil drought on growth,hormonal homeostasis,and the dynamics and distribution of free amino acids and phenolic compounds in rye at early vegetative stages and post-recovery.Drought triggered both general and organ-specific changes in endogenous phytohormones.A nonspecific response involved the accumulation of stress hormones abscisic acid(ABA)and salicylic acid(SA),alongside the suppression of growth hormones indole-3-acetic acid(IAA)and gibberellins.However,hormone dynamics and localization varied across plant organs.ABA and SA levels significantly increased in shoots of drought-stressed and recovered plants,corresponding with inhibited growth.Prolonged drought further enhanced ABA accumulation in both shoots and roots of recovered plants,while SA levels declined in roots but remained elevated in shoots.Drought also caused a substantial reduction in IAA,particularly in shoots,while gibberellins(GA_(3)+GA_(4))significantly decreased in roots.GA_(3)was predominant in most samples,except in the shoots of 2-day-old control plants.Post-recovery,IAA levels increased but remained below control values,while GA_(4)accumulation in roots led to a rise in total gibberellin levels.In contrast,shoot GA_(3)+GA_(4)levels declined,primarily due to GA_(3)reduction.The dominant free amino acids:aspartic acid,glutamic acid,glycine,alanine,and leucinedecreased significantly,underscoring their key role in stress adaptation.Increased flavonoid accumulation,especially in roots,suggests their involvement in antioxidant defense against oxidative stress.A significant increase in ABA and SA levels,along with a marked reduction in IAA and GA content in stressed rye plants occurred alongside a reduction in free amino acid content,accumulation of phenolic compounds,and an increase in flavonoid levels.These findings indicate distinct adaptation strategies in rye shoots and roots undermoderate soil drought.They provide a foundation for further research on drought resistance mechanisms in cereals and the development of strategies to enhance their adaptive potential.
基金supported by the Educational Commission of Anhui Province of China(No.KJ2021A0168)the Research Fund of Anhui Agricultural University(No.rc422112).
文摘The environmental impacts of acid mine drainage(AMD)from open-pit mining are profoundly detrimental,yet knowledge about its effects on paddy soil microbial communities,especially at greater depths,remains limited.In this investigation,we compared soils affected by AMD versus unaffected soil depth profiles in terms of bacterial diversity and community assembly.The profiles in AMD-polluted soils exhibited tight geochemical gradients,characterized by increased acidity,SO_(4)^(2-),NO_(3)^(-),and heavy metal content compared to unpolluted soils.Notably,AMD significantly diminished soil bacterial biodiversity.A depthwise analysis showed distinct microbial stratification,with certain bacteria like Candidatus_Solibacter and Candidatus_Koribacter predominated in polluted soils,while others like Haliangium and Nitrospira were more prevalent in control soils.Interestingly,despite variable soil conditions,predictedmetabolic pathways,particularly those involving carbon,nitrogen,and sulfur,showed relative stability.AMD pollution induced the upregulation of methylcoenzyme M reductase and sulfate reductase genes.Bacterial communities were more responsive to pH and nutrient content rather than heavy metals,with pH and SO_(4)^(2-)being the primary drivers of microbial diversity and distribution.Additionally,pHwas identified as the most significant influence on the predicted methane,sulfur,and nitrogen metabolism.Furthermore,deterministic processes played a more significant role in community assembly of polluted soils,while heterogeneous selection gained importance with increasing depth in control soils.Additionally,microbial co-occurrences,particularly positive interactions,were more prevalent in the polluted soils with reduced network modularity and keystone taxa.These findings offer insights into sustaining microbial diversity in extreme environments.
基金Under the auspices of the National Key Research and Development Program of China(No.2022YFD1500501)the Innovation Team Project of Northeast Institute of Geography and Agroecology,Chinese Academy of Sciences(No.2023CXTD02)+2 种基金the National Natural Science Foundation of China(No.41971066)the Key Laboratory Foundation of Mollisols Agroecology(No.2020ZKHT-03)the High Tech Fund Project of S&T Cooperation between Jilin Province and Chinese Academy of Sciences(No.2022SYHZ0018)。
文摘Water scarcity and soil salinization pose significant challenges to agriculture in the West Liaohe Plain,eastern Inner Mongolia,China.Shallow-buried drip irrigation can improve soil water use efficiency to alleviate water shortage in agriculture and the application of lignite humic acid reduces the adverse effects of soil salinization.However,further research is needed to investigate the effects of different application rates of lignite humic acid and humic acid-based combined amendment on soil physicochemical properties,nutrient contents,and crop yield in saline-sodic farmlands under shallow-buried drip irrigation.A two-year field experiment was conducted with control without any amendment(CK),three treatments amended with 3 t/ha(H1),6 t/ha(H2),and 12 t/ha(H3)lignite humic acid,and three application rates with 15 t/ha(T1),22.5 t/ha(T2),and 30 t/ha(T3)lignite humic acid-based combined amendment in 2021 and2022.The results showed that H3 reduced soil bulk density,p H,electrical conductivity,and total alkalinity,while increasing the contents of soil organic matter,total nitrogen,and available potassium in the two-year experiment.Moreover,the maize yield in H3 increased by an average of 35.5%.T2 decreased soil bulk density,p H,total alkalinity,and increased maize yield by 16.2%,compared to the first year.These results suggest that T2 consistently improved both soil quality and crop yield.Correlation analyses showed that lignite humic acid and its complexes promote maize growth and increase yield by increasing soil organic matter and total nitrogen while reducing soil salinity and total alkalinity.Based on the comprehensive analysis of the field data and the results of the comprehensive evaluation of soil quality,it was determined that the appropriate improvement measures for saline-sodic farmlands under shallow-buried drip irrigation are the application of 12 t/ha of lignite humic acid and 22.5 t/ha of lignite humic acid-based combined amendment.This study demonstrates the effectiveness of lignite humic acid and its combined amendment in mitigating the constraints of saline-sodic farmlands and enhancing crop yields,providing a sustainable solution for improving saline-sodic farmlands in the West Liaohe Plain.
基金National Natural Science Foundation of China(Nos.49831070 and 40125005)theNational Key Basic Research Support Foundation of China(No.G1999011807) the Jiangsu Provincial Foundation for Young Scientists(No.BQ98050).
文摘A pot experiment was catried out to study alleviation of soil acidity and Al toxicity by applying analkaline-stabilised sewage sludge product (biosolids) to an acid clay sandy loam (pH 5.7) and a strongly acidsandy loam (pH 4.5). Barley (Hondeum vulgare L. cv. Forrester) was used as a test crop and was grownin the sewage sludge-amended (33.5 t sludge DM ha-1) and unamended soils. The results showed that thealka1ine biosloids increased soil pH from 5.7 to 6.9 for the clay sandy loam and from 4.5 to 6.0 for the sandyloam. The sludge product decreased KCl-extractable Al from 0.1 to 0.0 cmol kg-1 for the former soil andfrom 4.0 to 0.1 cmol kg-1 for the latter soil. As a result, barley plants grew much better and grain yieldincreased greatly in the amended treatments compared with the unamended controls. These observationsindicate that alkaline-stabilised biosolids can be used as a liming material for remedying Al phytotoxicity instrongly acid soils by increasing soil pH and lowering Al bioavailability.
基金Project supported by the Ministry of Research,Technology and Higher Education,Republic of Indonesia(0386/E4/BP/2021)Universitas Gadjah Mada(1501407/UN1.FTK/SK/HK/2022)。
文摘In this decade,coal fly ash(CFA)is considered a potential secondary source of rare earth elements(REEs).However,most REEs in coal fly ash are encapsulated in aluminosilicate glass,making it challenging to recover them through acid leaching.In this study,a sequential alkaline-organic acid leaching was developed for the recovery of REEs from CFA.The effect of alkaline leaching using NaOH solution on the destructive ability of aluminosilicate glass,as well as the mineralogy and morphology changes of the resulting coal fly ash,was first studied.Furthermore,the effectiveness of alkaline leaching on the recovery ability of REEs through organic acid leaching was evaluated.The results show that the maximum leaching efficiency for Si and Al,which was obtained at the optimum alkaline leaching conditions,namely NaOH concentration of 10 mol/L,reaction temperature of 65℃,liquid/solid(L/S)ratio of 10 mL/g,and reaction time of 90 min,is 28%and 32%,respectively.The digestion reaction with NaOH lixiviants also causes coal fly ash to become more porous,making it advantageous in the organic acid-leaching process at the REEs recovery stage.The utilization of the desilicated residue produced from the digestion process in acid leaching effectively increases the overall REEs recovery from 32.2%to 77.6%.
基金supported by the National Key R&D Program of China (No.2019YFC1803704)。
文摘The digestibility of cadmium(Cd)in brown rice is directly related to amino acid metabolism in rice and human health.In our field study,three kinds of alkaline calcium-rich soil inorganic amendments(SIAs)at three dosages were applied to produce safe rice and improve the quality of rice in Cd-contaminated paddy.With the increased application of SIA,Cd content in iron plaque on rice root significantly increased,the transfer of Cd from rice root to grain significantly decreased,and then Cd content in brown rice decreased synchronously.The vitro digestibility of Cd in brown rice was estimated by a physiologically based extraction test.Results showed that more than 70%of Cd in brown rice could be digested by simulated gastrointestinal juice.Based on the total and digestible Cd contents in brown rice to evaluate the health risk,the application of 2.25 ton SIA/ha could produce safe rice in acidic slightly Cd-contaminated paddy soils.The amino acids(AAs)in brown rice were determined by high-performance liquid chromatography.The contents of 5 key AAs(KAAs)that actively respond to environmental changes increased significantly with the increased application of SIA.The structural equation model indicated that KAAs could be affected by the Cd translocation capacity from rice root to grain,and consequently altered the ratio of indigestible Cd in brown rice.The formation of indigestible KAAs-Cd complexes by combining KAAs(phenylalanine,leucine,histidine,glutamine,and asparagine)with Cd in brown rice could be considered a potential mechanism for reducing the digestibility of Cd.
基金Supported by the International Foundation of Science(No.C/4073-1)the National"Eleventh Five Years Plan"Key Project on Science and Technology of China(Nos.2006BAD05B02 and 2009BADC6B02)
文摘It is imperative to choose some low cost, available and effective ameliorants to correct soil acidity in southern China for sustainable agriculture. The present investigation dealt with the possible role of industrial byproducts, i.e., coal fly ash （CFA）, alkaline slag （AS）, red mud （RM） and phosphogypsum （PG） in correcting acidity and aluminum （Al） toxicity of soils under tea plantation using an indoor incubation experiment. Results indicated that CFA, AS and RM increased soil pH, while PG decreased the pHs of an Ultisol and an Alfisol. The increment of soil pH followed the order of RM 〉 AS 〉 CFA. All the industrial byproducts invariably decreased exchangeable Al and hence increased exchangeable Ca, Mg, K and Na and effective cation exchange capacity. RM, AS and lime decreased total soluble Al, exchangeable Al and organically bound Al. Formation and retention of hydroxyl-Al polymers were the principal mechanism through which Al phytotoxicity was alleviated by application of these amendments. In addition, the heavy metal contents in the four industrial byproducts constituted a limited environmental hazard in a short time at the rates normally used in agriculture. Therefore, the short-term use of the byproducts, especially AS and RM, as amendments for soil acidity and AI toxicity in acid soils may be a potential alternative to the traditional use of mined gypsum and lime.
基金funded by the National Key Research and Development of China(2016YFD0200302)the National Key Basic Research Program of China(2014CB441003)
文摘Extensive acidic soils,which suffer from accelerated soil acidification,are found in southern China.Soil acidity,aluminum toxicity,and nutrient deficiencies severely limited crop productivity in acidic soils.It has been widely reported that crop residue biochars can ameliorate acidic soils and increase crop productivity.Here,we summarized the positive effects and mechanisms involved in the correction of soil acidity,the alleviation of aluminum toxicity and the increase of soil pH buffering capacity by crop residue biochars.The carbonate,oxygen-containing functional groups and silicates in biochars are the major components responsible for their efficacy in amending acidic soils and resisting soil re-acidification.We conclude that application of crop residue biochars may be a better option than traditional liming to ameliorate acidic soils.Nonetheless,further researches into soil acidification are still required to address some issues that are controversial and poorly understood.
基金This study was supported by the National Natural Science Foundation of China （No. 41401336）, the Na- tural Science Foundation of Jiangsu Province, China （No. BK20130105）, the State Key Laboratory of Soil and Sustainable Agriculture, Chinese Academy of Sci-ence （No. Y412201452）, and the Environmental Pro- tection Public Benefit Research Foundation of China （No. 201309036）. We thank the three anonymous refe- rees for their helpful comments.
文摘Strongly acidic soils （pH 〈 5.0） are detrimental to tea （Camellia sinensis） production and quality. Little information exists on the ability of surface amendments to ameliorate subsoil acidity in the tea garden soils. A 120-d glasshouse column leaching experiment was conducted using commonly available soil ameliorants. Alkaline slag （AS） and organic residues, pig manure （PM） and rapeseed cake （RC） differing in ash alkalinity and C/N ratio were incorporated alone and in combination into the surface （0-15 cm） of soil columns （10 cm internal diameter x 50 cm long） packed with soil from the acidic soil layer （15-30 cm） of an Ultisol （initial pH -- 4.4）. During the 120-d experiment, the soil columns were watered （about 127 mm over 9 applications） according to the long-term mean annual rainfall （1 143 mm） and the leachates were collected and analyzed. At the end of the experiment, soil columns were partitioned into various depths and the chemical properties of soil were measured. The PM with a higher C/N ratio increased subsoil pH, whereas the RC with a lower C/N ratio decreased subsoil pH. However, combined amendments had a greater ability to reduce subsoil acidity than either of the amendments alone. The increases in pH of the subsoil were mainly ascribed to decreased base cation concentrations and the decomposition of organic anions present in dissolved organic carbon （DOC） and immobilization of nitrate that had been leached down from the amended layer. A significant （P 〈 0.05） correlation between alkalinity production （reduced exchangeable acidity - N-cycle alkalinity） and alkalinity balance （net alkalinity production - N-cycle alkalinity） was observed at the end of the experiment. Additionally, combined amendments significantly increased （P ~ 0.05） subsoil cation concentrations and decreased subsoil A1 saturation （P 〈 0.05）. Combined applications of AS with organic amendments to surface soils are effective in reducing subsoil acidity in high-rainfall areas. Further investigations under field conditions and over longer timeframes are needed to fully understand their practical effectiveness in ameliorating acidity of deeper soil layers under naturally occurring leaching regimes.
基金supported by the Chinese Postdoctoral Science Foundation(No.2015M580110)the National Key Research and Development Program of China(No.2016YFC0501306)。
文摘Burying a straw layer and applying flue gas desulphurization(FGD)gypsum are effective practices to ameliorate soil salinization or alkalization and to increase crop yield;however,little information exists on the effects of such integration in saline-alkali soils.A soil column experiment was conducted to investigate the effects of a straw layer plus FGD gypsum on soil salinity and alkalinity.We placed a straw layer(5 cm thick)at a depth of 30 cm and mixed FGD gypsum into the 0–20 cm soil layer at application rates of 7.5,15.0,22.5,and 30.0 t ha^-1,with no straw layer and FGD gypsum as a control(CK).The soil water content in the 0–30 cm soil layer was significantly higher(>7.8%)in the treated soil profiles after infiltration than in the CK,but decreased after evaporation.The electrical conductivity(EC)of the 10–30 cm soil layer was 230.2%and 104.9%higher in the treated soil profiles than in the CK after infiltration and evaporation,respectively,and increased with increasing rates of FGD gypsum application,with Ca^2+and SO4^2-being the main dissolved salts.Compared to those in the CK,the concentrations of Na^+,Cl^-,and HCO3-decreased in the treated soil profiles at depths above 55 cm,but the other soluble ions increased,after infiltration.A similar trend occurred after evaporation for all soluble ions except for HCO3-.The p H and exchangeable sodium percentage in the treated soil profiles were significantly lower than those in the CK over the entire profile,and decreased with increasing FGD gypsum application rates.Therefore,the incorporation of a straw layer plus FGD gypsum can reduce salinity and alkalinity,but the quantity of FGD gypsum should be controlled in saline-alkali soils.
基金Supported by the National Basic Research Program(973 Program)of China(No.2014CB441003)the National Natural Science Foundation of China(No.41271010)
文摘This investigation was conducted by using alkaline slag and crop straw biochars to reduce acidity of an acidic Ultisol through incubation and pot experiments with lime as a comparison. The soil was amended with different liming materials: lime(1 g kg-1),alkaline slag(2 and 4 g kg-1), peanut straw biochar(10 and 20 g kg-1), canola straw biochar(10 and 20 g kg-1) and combinations of alkaline slag(2 g kg-1) and biochars(10 g kg-1) in the incubation study. A pot experiment was also conducted to observe the soybean growth responses to the above treatments. The results showed that all the liming materials increased soil p H and decreased soil exchangeable acidity. The higher the rates of alkaline slag, biochars, and alkaline slag combined with biochars, the greater the increase in soil p H and the reduction in soil exchangeable acidity. All the amendments increased the levels of one or more soil exchangeable base cations. The lime treatment increased soil exchangeable Ca2+, the alkaline slag treatment increased exchangeable Ca2+and Mg2+levels, and the biochars and combined applications of alkaline slag with biochars increased soil exchangeable Ca2+, Mg2+and K+and soil available P. The amendments enhanced the uptake of one or more nutrients of N, P, K, Ca and Mg by soybean in the pot experiment. Of the different amendments, the combined application of alkaline slag with crop straw biochars was the best choice for increasing base saturation and reducing soil acidity of the acidic Ultisol. The combined application of alkaline slag with biochars led to the greatest reduction in soil acidity, increased soil Ca, Mg, K and P levels, and enhanced the uptake of Ca, Mg, K and P by soybean plants.
文摘The sorption of a triazol derivative, 1-(4-chlorophenyl)- 4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl)penten-3-ol with a common name of S3307D, on fifteen soils and three H_2O_2-treated soils was investigated. The sorption isotherm for each untreated and treated soil was non-linear, and was best fitted to Freundlich sorption equation. Soils containing high amount of clay content or organic matter or both sorbed much higher amounts of the chemical than soils that had low contents of these soil constituents. H_2O_2-treated soils showed considerable sorptive affinity for S3307D. It was concluded that both organic matter and mineral fraction in natural soils contributed to the sorption of the basic compound. Sorption by the H_2O_2 treated soils increased as suspension pH decreased, but all suspension pHs exceeded the pKa of the compound by more than two units. This implies that organic base protonation can occur on surfaces of soil components, and surface acidity (exchangeable acidity ) is important in sorption process of the organic base rather than suspension pH.
文摘An extremely acidified acid sulfate soil (ASS) was investigated to characterize its soluble and exchangeableacidity. The results showed that soluble acidity of a sample determined by titration with a KOH solutionwas much significantly greater than that indicated by pH measured using a PH meter, particularly for theextremely acidic soil samples. This is because the total soluble acidity of the extremely acidic soil sampleswas mainly composed of various soluble Al and Fe species, possibly in forms of Al sulfate complexes (e.g.,AISO4) and ferrous Fe (Fe2+). It is therefore suggested not to use pH alone as an indicator of soluble acidityin ASS, particularly for extremely acidic ASS. It is also likely that AISO4+ actively pericipated in cationexchange reactions. It appears that the possible involvement of this Al sulfate canon in the canon adsorptionhas significant effect on increasing the amount of acidity being adsorbed by the soils.
文摘The acidity regimes of representative soils on the north slope of the Changbai Mountains were examined through determinations of PH and pCa of the soil paste as well as in-site determinations. For soils under broad-leaf forest or broad-leaf-Korean pine forest, the pH decreased from the litter to lower layers gradually until it did not change or decreased further slightly. For soils under coniferous forest or Ermans birch forest,there was a minimum in pH at a depth of 3～6 cm where the content of humus was high. The pCa increased gradually from the soil surface downward to a constant value. The lime potential (pH-0.5pCa) showed a similar trend as the PH in its distribution. For a given soil, the measured pH value of the thick paste, ranging from 4.5 to 5.5, was lower by about 0.5 units than the value determined by the conventional method with a water to soil ratio of 5:1. The PH determined in site was even lower. It was found that there was a fairly close relationship between soil acidity and the type of vegetation. The pH showed a trend of decreasing from soils under broad-leaf forest through broad-leaf-conifer mixed forest and coniferous forest to Ermans birch forest, and the pCa showed an opposite trend in variation.
文摘Some Inceptisols representing the Singla catchment area in Karimgaungedistrict of Assam, India, were studied for lime requirement as influenced by the nature of soilacidity. The electrostatically bonded (EB)-H^+ and EB-Al^(3+) acidities constituted 33 and 67percent of exchangeable acidity while EB-H^+, EB-Al^(3+), exchangeable and pH-dependent aciditiescomprised 6, 14, 20 and 80 percent of total potential acidity. The pH-dependent acidity made a majorcontribution towards the total potential acidity (67%～84%). Grand mean of lime requirementdetermined by the laboratory incubation method and estimated by the methods of New Woodruff,Woodruff and Peech as expressed in MgCaCO_3 ha^(-1) was in the order: Woodruff (15.6) > New Woodruff(14.9) > Peech (5.1) > incubation (5.0). Correlations analysis among different forms of acidity andlime requirement methods with selected soil properties showed that pH in three media, namely water,1 mol L^(-1) KC1 and 0.01 mol L^(-1) CaCl_2, had a significant negative correlation with differentforms of acidity and lime requirement methods. Exchangeable Fe and Al showed significant positivecorrelations with EB-Al^(3+) acidity, exchangeable acidity, pH-dependent acidity and total potentialacidity, and also lime requirement methods. Extractable Al showed positive correlations withdifferent forms of acidity except EB-H^+ and EB-Al^(3+) acidities. The lime requirement by differentmethods depended upon the extractable aluminium. Significant positive correlations existed betweenlime requirements and different forms of acidity of the soils except EB-H^+ acidity and incubationmethod. The nature of soil acidity was mostly pH-dependent. Statistically, the Woodruff method didslightly better than the New Woodruff, incubation and Peech methods at estimating lime requirementand hence the Woodruff procedure may be recommended for routine soil testing because of its speedand simplicity.
基金co-funded by the National Natural Science Foundation of China(U204020742277323)+2 种基金the 111 Project of Hubei Province(2021EJD026)the open fund of Key Laboratory of Geological Hazards on Three Gorges Reservoir Area(China Three Gorges University)Ministry of Education(2022KDZ24).
文摘Soil aggregate is the basic structural unit of soil,which is the foundation for supporting ecosystem functions,while its composition and stability is significantly affected by the external environment.This study was conducted to explore the effect of external environment(wetting-drying cycles and acidic conditions)on the soil aggregate distribution and stability and identify the key soil physicochemical factors that affect the soil aggregate stability.The yellow‒brown soil from the Three Gorges Reservoir area(TGRA)was used,and 8 wetting-drying conditions(0,1,2,3,4,5,10 and 15 cycles)were simulated under 4 acidic conditions(pH=3,4,5 and 7).The particle size distribution and soil aggregate stability were determined by wet sieving method,the contribution of environmental factors(acid condition,wetting-drying cycle and their combined action)to the soil aggregate stability was clarified and the key soil physicochemical factors that affect the soil aggregate stability under wetting-drying cycles and acidic conditions were determined by using the Pearson’s correlation analysis,Partial least squares path modeling(PLS‒PM)and multiple linear regression analysis.The results indicate that wetting-drying cycles and acidic conditions have significant effects on the stability of soil aggregates,the soil aggregate stability gradually decreases with increasing number of wetting-drying cycles and it obviously decreases with the increase of acidity.Moreover,the combination of wetting-drying cycles and acidic conditions aggravate the reduction in the soil aggregate stability.The wetting-drying cycles,acidic conditions and their combined effect imposes significant impact on the soil aggregate stability,and the wetting-drying cycles exert the greatest influence.The soil aggregate stability is significantly correlated with the pH,Ca^(2+),Mg^(2+),maximum disintegration index(MDI)and soil bulk density(SBD).The PLS‒PM and multiple linear regression analysis further reveal that the soil aggregate stability is primarily influenced by SBD,Ca^(2+),and MDI.These results offer a scientific basis for understanding the soil aggregate breakdown mechanism and are helpful for clarifying the coupled effect of wetting-drying cycles and acid rain on terrestrial ecosystems in the TGRA.
