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
Due to historical and ongoing industrial practices, lead contamination in urban soils presents substantial health risks, primarily due to its capacity to readily migrate from the soil to humans. This research focused ...Due to historical and ongoing industrial practices, lead contamination in urban soils presents substantial health risks, primarily due to its capacity to readily migrate from the soil to humans. This research focused on the influence of soil pH, organic matter, and clay content on extractable lead amounts. Sixty-four soil samples from Muncie, Indiana, were analyzed, revealing that the examined factors accounted for 21.71% of the Pb mg/Kg-dry variable variance (p −0.4, p < 0.001), with XRD and FTIR analyses confirming the binding affinity of clay minerals with lead. In contrast, no significant relationships were found between Pb concentrations and soil pH (r = 0.07;p = 0.59) or organic matter content (r = 0.12;p = 0.34). Elucidating the interactions between lead, clay minerals, and other soil constituents is crucial for addressing lead-contaminated soils and reducing environmental and health impacts.展开更多
With the hypothesis that iron(Fe) deficiency responsive genes may play a role in Fe toxicity conditions,we studied five such genes OsNAS1,OsNAS3,OsIRO2,OsIRO3 and OsYSL16 across six contrasting rice genotypes for expr...With the hypothesis that iron(Fe) deficiency responsive genes may play a role in Fe toxicity conditions,we studied five such genes OsNAS1,OsNAS3,OsIRO2,OsIRO3 and OsYSL16 across six contrasting rice genotypes for expression under high Fe and low phosphorus(P) conditions,and sequence polymorphism.Genotypes Sahbhagi Dhan,Chakhao Poirieton and Shasharang were high yielders with no bronzing symptom visible under Fe toxic field conditions,and BAM350 and BAM811 were low yielders but did not show bronzing symptoms.Hydroponic screening revealed that the number of crown roots and root length can be traits for consideration for identifying Fe toxicity tolerance in rice genotypes.Fe contents in rice roots and shoots of a high-yielding genotype KMR3 showing leaf bronzing were significantly high.In response to 24 h high Fe stress,the expression levels of OsNAS3 were up-regulated in all genotypes except KMR3.In response to 48 h high Fe stress,the expression levels of OsNAS1 were3-fold higher in tolerant Shasharang,whereas in KMR3,it was significantly down-regulated.Even in response to 7 d excess Fe stress,the transcript abundances of OsIRO2 and OsNAS3 were contrasting in genotypes Shasharang and KMR3.This suggested that the reported Fe deficiency genes had a role in Fe toxicity and that in genotype KMR3 under excess Fe stress,there was disruption of metal homeostasis.Under the 48 h low P conditions,OsIRO2 and OsYSL16 were significantly up-regulated in Fe tolerant genotype Shasharang and in low P tolerant genotype Chakhao Poirieton,respectively.In silico sequence analysis across 3 024 rice genotypes revealed polymorphism for 4 genes.Sequencing across OsIRO3and OsNAS3 revealed nucleotide polymorphism between tolerant and susceptible genotypes for Fe toxicity.Non-synonymous single nucleotide polymorphisms and insertion/deletions(InDels) differing in tolerant and susceptible genotypes were identified.A marker targeting 25-bp InDel in OsIRO3,when run on a diverse panel of 43 rice genotypes and a biparental population,was associated with superior performance for yield under acidic lowland field conditions.This study highlights the potential of one of the vital genes involved in Fe homeostasis as a genic target for improving rice yield in acidic soils.展开更多
The inhibition of nitrification by mixing nitrification inhibitors(NI)with fertilizers is emerging as an effective method to reduce fertilizer-induced nitrous oxide(N_(2)O)emissions.The additive 3,4-dimethylpyrazole p...The inhibition of nitrification by mixing nitrification inhibitors(NI)with fertilizers is emerging as an effective method to reduce fertilizer-induced nitrous oxide(N_(2)O)emissions.The additive 3,4-dimethylpyrazole phosphate(DMPP)apparently inhibits ammonia oxidizing bacteria(AOB)more than ammonia oxidizing archaea(AOA),which dominate the nitrification in alkaline and acid soil,respectively.However,the efficacy of DMPP in terms of nitrogen sources interacting with soil properties remains unclear.We therefore conducted a microcosm experiment using three typical Chinese agricultural soils with contrasting pH values(fluvo-aquic soil,black soil and red soil),which were fertilized with either digestate or urea in conjunction with a range of DMPP concentrations.In the alkaline fluvo-aquic soil,fertilization with either urea or digestate induced a peak in N_(2)O emission(60μg N kg^(-1)d^(-1))coinciding with the rapid nitrification within 3 d following fertilization.DMPP almost eliminated this peak in N_(2)O emission,reducing it by nearly 90%,despite the fact that the nitrification rate was only reduced by 50%.In the acid black soil,only the digestate induced an N_(2)O emission that increased gradually,reaching its maximum(20μg N kg^(-1)d^(-1))after 5–7 d.The nitrification rate and N_(2)O emission were both marginally reduced by DMPP in the black soil,and the N_(2)O yield(N_(2)O-N per NO2–+NO3–-N produced)was exceptionally high at 3.5%,suggesting that the digestate induced heterotrophic denitrification.In the acid red soil,the N_(2)O emission spiked in the digestate and urea treatments at 50 and 10μg N kg^(-1)d^(-1),respectively,and DMPP reduced the rates substantially by nearly 70%.Compared with 0.5%DMPP,the higher concentrations of DMPP(1.0 to 1.5%)did not exert a significantly(P<0.05)better inhibition effect on the N_(2)O emissions in these soils(either with digestate or urea).This study highlights the importance of matching the nitrogen sources,soil properties and NIs to achieve a high efficiency of N_(2)O emission reduction.展开更多
Acid soils occupy approximately 50% of potentially arable lands.Improving crop productivity in acid soils,therefore,will be crucial for ensuring food security and agricultural sustainability.High soil acidity often co...Acid soils occupy approximately 50% of potentially arable lands.Improving crop productivity in acid soils,therefore,will be crucial for ensuring food security and agricultural sustainability.High soil acidity often coexists with phosphorus(P) deficiency and aluminum(Al) toxicity,a combination that severely impedes crop growth and yield across wide areas.As roots explore soil for the nutrients and water required for plant growth and development,they also sense and respond to below-ground stresses.Within the terrestrial context of widespread P deficiency and Al toxicity pressures,plants,particularly roots,have evolved a variety of mechanisms for adapting to these stresses.As legumes,soybean(Glycine max) plants may acquire nitrogen(N) through symbiotic nitrogen fixation(SNF),an adaptation that can be useful for mitigating excessive N fertilizer use,either directly as leguminous crop participants in rotation and intercropping systems,or secondarily as green manure cover crops.In this review,we investigate legumes,especially soybean,for recent advances in our understanding of root-based mechanisms linked with root architecture modification,exudation and symbiosis,together with associated genetic and molecular strategies in adaptation to individual and/or interacting P and Al conditions in acid soils.We propose that breeding legume cultivars with superior nutrient efficiency and/or Al tolerance traits through genetic selection might become a potentially powerful strategy for producing crop varieties capable of maintaining or improving yields in more stressful soil conditions subjected to increasingly challenging environmental conditions.展开更多
[Objectives]This study was conducted to improve acidic soil and enhance the quality of tobacco leaves.[Methods]The effects of different microbial fertilizers on improving acidic tobacco-planting soil and tobacco leaf ...[Objectives]This study was conducted to improve acidic soil and enhance the quality of tobacco leaves.[Methods]The effects of different microbial fertilizers on improving acidic tobacco-planting soil and tobacco leaf quality were investigated through plot experiments.[Results]The application of microbial fertilizers could improve the pH value of acidic soil,and composite microbial agent A showed the best application effect.The application of bio-organic fertilizer was beneficial to improving the contents of available phosphorus and available boron in acidic soil.The application of composite microbial agent A was beneficial to improving the contents of available phosphorus and available potassium in acidic soil,and could promote the growth of tobacco plants and improve the economic traits of flue-cured tobacco and the coordination of chemical components in tobacco leaves.The application of composite microbial agent B led to a downward trend in the content of available boron in acidic soil.The application of composite microbial agent B could promote the absorption of nutrients by tobacco plants,and improve their disease resistance and the quality of tobacco leaves.Due to the differences in functional microorganisms contained,the application effects of different microbial fertilizers in improving acidic tobacco-planting soil and improving tobacco leaf quality varied.Overall,the application of microbial fertilizers could increase soil pH,activate soil nutrients,promote tobacco growth,enhance disease resistance,increase tobacco output value,and improve tobacco quality.Microbial fertilizers have good application prospects in improving acidic soil and improving tobacco quality.[Conclusions]The application of microbial fertilizers to improve acidic tobacco-planting soil can ensure the normal growth and development of tobacco plants and the improvement of tobacco leaf quality,achieving high-quality and sustainable development of Zhaotong tobacco.展开更多
This study is a contribution to improving rice productivity on acidic plateau soils of the tropical rainforest zone. It is based on taking into account the cationic balances of the soil in order to optimize the phosph...This study is a contribution to improving rice productivity on acidic plateau soils of the tropical rainforest zone. It is based on taking into account the cationic balances of the soil in order to optimize the phosphorus (P) nutrition of rice on these acidic soils, where this nutrient constitutes a limiting factor for agricultural production. Three (3) pot trials were conducted in Adiopodoumé in the forested south of Côte d’Ivoire. The interactive effects of calcium carbonate (0, 25, 50 and 75 kg Ca ha<sup>−1</sup>) and magnesium sulfate (0, 25, 50 and 75 kg Mg ha<sup>−1</sup>) were evaluated on the response of NERICA 5 rice at doses 0, 25, 50 and 75 kg P ha<sup>−1</sup> of natural phosphate from Togo, applied only once at the start of the experiment. Additional fertilizers of nitrogen (N) (100 kg N ha<sup>−1</sup>) and potassium (K) (50 kg KCl ha<sup>−1</sup>) were added to each of the tests in a split-plot device. The test results revealed a paddy production potential of approximately 3 to 5 t⋅ha<sup>−1</sup> for NERICA 5 on an acidic soil, under the effect of the interaction of P, Ca and Mg. The quadratic response of rice yield to the doses of these fertilizers would be more dependent on their balance, itself influenced by Ca nutrition. For the sustainability and maintenance of rice production in agro-ecology studied, it was recommended doses of 38 kg Ca ha<sup>−1</sup>, 34 kg Mg ha<sup>−1</sup> in a Ca/Mg ratio (1/1) with intakes of 41 kg P ha<sup>−1</sup>, overall in a ratio 1/1/1 (P/Ca/Mg) more favorable to the availability of free iron considered a guiding element of mineral nutrition. Thus, these promising results should be confirmed in a real environment for better management of the fertilization of rice cultivated on acidic plateau soils in Côte d’Ivoire.展开更多
Phosphorus bioavailability has long been a recurring problem in tropical acid soils. A pot experiment was carried out during three (3) successive rice production cycles at Adiopodoumé to evaluate the response of ...Phosphorus bioavailability has long been a recurring problem in tropical acid soils. A pot experiment was carried out during three (3) successive rice production cycles at Adiopodoumé to evaluate the response of the NERICA 5 rice accession to various doses of calcium, magnesium and phosphorous. The experiment was conducted using a randomized split-plot design. The interactive effects of calcium carbonate (0, 25, 50 and 75 kg·Ca·ha<sup>-1</sup>) and magnesium sulfate (0, 25, 50 and 75 kg·Mg·ha<sup>-1</sup>) and Togo natural phosphate (0, 25, 50 and 75 kg·P·ha<sup>-1</sup>) were determined at each production cycle. The results showed that single-dose natural phosphate supplementation for three cropping cycles resulted in an average enrichment of around 2 mg·P·kg<sup>-1</sup> after each trial following its continuous dissolution, with an increase in DSP (33.31% to 70.52%). The study revealed one strategy for managing and enhancing native P with cations and another for exogenous P: there would be a synergy of Ca/Mg on native P, whereas an antagonism would characterize the two parameters in phosphate fertilization.展开更多
Soil aluminum phytotoxicity has been a major research area since the inception of modern soil science. Acid soils, which typically manifest plant aluminum toxicity, are frequently dedicated to food production, thus yi...Soil aluminum phytotoxicity has been a major research area since the inception of modern soil science. Acid soils, which typically manifest plant aluminum toxicity, are frequently dedicated to food production, thus yield and quality reductions influence food security. This manuscript reviews our modern understanding of 1) soil aluminum hydrolysis and polymerization, 2) aluminum complexation with inorganic and organic anions, 3) aluminum interference with vital plant physiological processes, 4) aluminum and forest ecosystem productivity, and 5) demonstrates the software simulation of aluminum reactivity and its role in predicting soil behavior. The manuscript also provides a perspective for future soil-aluminum research critical to maintaining food security and food quality.展开更多
The popularization of <i>Dioscorea dumetorum</i> (Dioscoreaceae), a nutritious yam species is still marginal due to constraints such as the low interest of research, poor cultural practices, insufficient a...The popularization of <i>Dioscorea dumetorum</i> (Dioscoreaceae), a nutritious yam species is still marginal due to constraints such as the low interest of research, poor cultural practices, insufficient and expensive seeds, pests, and diseases. The latter pushes producers to use about 50% of their harvest as seed for the next planting season. The lack of a specific fertilizer formulation for yam production on the oxysols of Cameroon is another constraint. This study was aimed at enhancing the availability of quality seeds through the characterization of five yam accessions. One experiment was performed to determine the effect of cultivar and origin of tuber sets on their germination rate. The <span>second concerned the evaluation of cultivars and soil treatment effects on ag</span>ronomic parameters of yam seedlings. Yam cultivars were subjected to nine fertilizer formulations as follows: T0: no fertilizer;T1: mycorrhizal fungi (MF) + 150 g manure + peanut waste;T2: 25 g chemical fertilizer (20.10.10);T3: MF + peanut waste;T4: 16 g chemical fertilizer (12.6.20);T5: 25 g (20.10.10) +100 g CaO + 150 g manure;T6: 100 g CaO + 150 g manure;T7: 20 g tropicote + 2 g DAP (Diammonium phosphate, a reference starter fertilizer coded N18P46) + 100 g CaO + 150 g manure;and T8: mycorrhiza. These treatments were tested in a factorial design. Results show that Ibo sweet 3 and Mabondji sweet white 1 yam accessions were less affected by anthracnose disease on the aerial parts. Guzang 1 showed the best germination rate and yield, making it appropriate for cultivation in the region. Soil treatments, T2, T5, T7 and T8 significantly increased the yield of yam cultivars. Mycorrhiza treatment alone gave a better response to seed weight, indicating the interest of this biofertilizer as a solution for good seedling production. These fertilizer treatments can be recommended to farmers for more seed production with optimum seed weight (300 g).展开更多
Ferralsols form a dominant type of soil on which most crops are grown in the Lake Victoria agro-ecological zone. Soil acidity has been recognized among the most important agricultural problems in such soils, which adv...Ferralsols form a dominant type of soil on which most crops are grown in the Lake Victoria agro-ecological zone. Soil acidity has been recognized among the most important agricultural problems in such soils, which adversely affect crop production and productivity. A study was conducted with the objective of determining the effect of applying low rates of lime and chicken manure on selected soil chemical properties. Using a Split Plot Factorial Randomized Complete Block Design, agricultural lime (0.0, 0.5, 1.0, 1.5 & 2.0 t·ha<sup>-1</sup>) as the main plot and chicken manure (0.0, 1.0, 2.0 & 3.0 t·ha<sup>-1</sup>) as sub-plot were applied, replicated three times. The test crop was common bean var. NABE 15. The experiment was conducted for three rainy seasons, two seasons on-station and one season on-farm on Ferralsol soil in the Lake Victoria crescent of central Uganda. The results showed that applying low rates of lime with chicken manure significantly (p ·ha<sup>-1</sup> lime was applied with the four chicken manure rates in Mukono. From the study, we recommend the application of small quantities of lime at 1.0 t·ha<sup>-1</sup> with either 2.0 or 3.0 t·ha<sup>-1</sup> chicken manure.展开更多
This paper described the use of fy ash for soil amelioration of acidic soils to promote plant growth.In mining sites,acid sulfate soils/rocks,which contain sulfde minerals(e.g.pyrite FeS_(2)),have appeared as a result...This paper described the use of fy ash for soil amelioration of acidic soils to promote plant growth.In mining sites,acid sulfate soils/rocks,which contain sulfde minerals(e.g.pyrite FeS_(2)),have appeared as a result of overburden excavation.The excessively acidic condition inhibits plant growth due to the dissolution of harmful elements,such as Al,Fe,and Mn.Fly ash,an alkaline byproduct of coal combustion generated in thermal power plants is expected to be adopted to ameliorate acidic soils.However,the mixing ratio of fy ash must be considered because excessive addition of fy ash can have a negative impact on plant growth due to its physical/chemical properties.The pot trials using Acacia mangium demonstrate the evolution of plant growth with a 5%–10%addition of fy ash into acidic soil.When the acidic soil has a high potential for metal dissolution,the metal ions leached from the acidic soil are large,making it difcult to improve plant growth due to osmotic and ionic stress.This work suggests that the efects of fy ash on metal ions leached from the soil have to be considered for the amelioration of acidic soil.展开更多
Cation exchange capacity (CEC) is one of the most important properties of soils. The NH<sub>4</sub>OAc (pH = 7.0) exchange method is usually recommended to determine CEC (CEC<sub>1</sub>) of al...Cation exchange capacity (CEC) is one of the most important properties of soils. The NH<sub>4</sub>OAc (pH = 7.0) exchange method is usually recommended to determine CEC (CEC<sub>1</sub>) of all soils with different pH values, particularly for studies on soil taxonomy. But comparatively the BaCl<sub>2</sub>-MgSO<sub>4</sub> forced-exchange method is more authentic in determining CEC (CEC<sub>2</sub>) of tropical and subtropical highly-weathered acid soils. But so far little is known about the difference between CEC<sub>1</sub> and CEC<sub>2</sub>. In this study, the physiochemical data of 114 acid B horizon soils from 112 soil series of tropical and subtropical China were used, CEC<sub>1</sub> and CEC<sub>2</sub> were determined and compared, the influencing factors were analyzed for the difference between CEC<sub>1</sub> and CEC<sub>2</sub>, and then a regression model was established between CEC<sub>1</sub> and CEC<sub>2</sub>. The results showed that CEC<sub>2</sub> was significantly lower than CEC<sub>1</sub> (p < 0.01), CEC<sub>2</sub> was 14.76% - 63.31% with a mean of 36.32% of CEC<sub>1</sub>. In view of the contribution to CEC from other properties, CEC<sub>2</sub> was mainly determined by pH (45.92%), followed by silt (21.05%), free Fe<sub>2</sub>O<sub>3</sub> (17.35%) and clay contents (12.76%), CEC<sub>1</sub> was mainly decided by free Fe<sub>2</sub>O<sub>3</sub> content (40.38%), followed by pH (28.39%) and silt content (27.29%;and the difference between CEC<sub>1</sub> and CEC<sub>2</sub> was mainly affected by free Fe<sub>2</sub>O<sub>3</sub> (50.92%), followed by silt content (26.46%) and pH (21.80%). The acceptable optimal regression model between CEC<sub>2</sub> and CEC<sub>1</sub> was established as CEC<sub>2</sub> = 2.3114 × CEC<sub>1</sub><sup>1.1496</sup> (R<sup>2</sup> = 0.410, P < 0.001, RMSE = 0.15). For the studies on soil taxonomy, the BaCl<sub>2</sub>-MgSO<sub>4</sub> forced-exchange method is recommended in determining CEC of the highly-weathered acid soils in the tropical and subtropical regions.展开更多
Plant tolerance to aluminum(Al)toxicity can be enhanced by an ectomycorrhizal(ECM)fungus through biological filtering or physical blockage.To understand the roles of ECM colonization in Al absorption with regard to Al...Plant tolerance to aluminum(Al)toxicity can be enhanced by an ectomycorrhizal(ECM)fungus through biological filtering or physical blockage.To understand the roles of ECM colonization in Al absorption with regard to Al tolerance,Pinus massoniana seedlings were inoculated with either Lactarius deliciosus(L.:Fr.)Gray isolate 2 or Pisolithus tinctorius(Pers.)Coker et Couch isolate 715 and cultivated in an acid yellow soil with or without 1.0 mM Al^(3+)irrigation for 10 weeks.Biomass production,Al bioaccumulation and transport in seedlings colonized by the two ECM fungi were compared,and the three absorption kinetics(pseudo-first order,pseudo-second order and intraparticle diffusion)models used to evaluate variances in root Al^(3+)absorption capacity.Results show that both fungi increased aboveground biomass and Al tolerance of P.massoniana seedlings,but L.deliciosus 2 was more effective than P.tinctorius 715.Lower Al absorption capacity,fewer available active sites and decreased affinity and boundary layer thickness for Al^(3+),and higher Al accumulation and translocation contributed to the increased Al tolerance in the ECM-inoculated seedlings.These results advance our understanding of the mechanisms and strategies in plant Alto lerance conferred by ECM fungi and show that inoculation with L.deliciosus will better enhance Al tolerance in P.massoniana seedlings used for forest plantation and ecosystem restoration in acidic soils,particularly in Southwest China and similar soils worldwide.展开更多
Soil acidification and phosphorus deficiency are a major constraint to crop production in tropical soils.Use of conventional liming materials is associated with some limitations viz:inability to solely improve nitroge...Soil acidification and phosphorus deficiency are a major constraint to crop production in tropical soils.Use of conventional liming materials is associated with some limitations viz:inability to solely improve nitrogen and available phosphorus in soils,loss of soil organic carbon and soil aggregate stability.Liming and fertilizer potentials of leaves from three plant materials(Tithonia diversifolia(TL),Imperata cylindrica(SG)and Gliricidia sepium(GL))widely growing in Ogbomoso,southwest Nigeria,were tested under incubation condition.Each of the plant material was applied at the rate of 10 t·hm^(-2) with and without 50%concentration of NPK 15:15:15-urea mix in 500 g acidic soil.Sole lime applied at 1 t·hm^(-2),sole NPK 15:15:15 applied at 60 kg·hm^(-2) mixed with urea at 60 kg N·hm^(-2) and an unamended soil were compared in completely randomized design in three replicates.The treated soils were incubated for 12 weeks.Thereafter,maize seeds were raised in each pot for a period of 3 weeks.Data collected were subjected to analysis of variance.Regression analysis was used to predict contributions of increased soil p H in plant material treated soils to exchangeable Al,H,dry root weight of maize and available phosphorus.Results indicated that sole plant materials were the order SG>TL>GL significantly(p<0.05)reduced exchangeable acidity compared to unamended and sole NPK.Sole NPK had the highest exchangeable acidity(4.7 cmol·kg^(-1))compared to unamended soil(3.3 cmol·kg^(-1))and sole lime(2.7 cmol·kg^(-1)).Application of sole Tithonia diversifolia increased available phosphorus by 214%and 97%compared to unamended and sole NPK treated soils respectively.Sole plant materials increased maize root weight by 33%compared to sole NPK.Increasing soil p H at harvesting in plant material treated soils significantly reduced exchangeable H and A_1.Soil p H was responsible for up to 33%and 53%reductions in exchangeable Al and H,respectively.This culminated into up to 22%increases in dry root weight of maize seedling.Present results showed ability of the plant materials tested to ameliorate soil acidity and improved soil available phosphorus.The plant materials should be explored for using as green manure and composting feedstock.It will go a long way to reduce high dosage use of conventional liming and fertilizer materials on acidic nutrient degraded soils.展开更多
Tropical soils are usually highly acidic and this may hamper mango trees nutrition and production. The objective of this work was to evaluate the effects of lime doses applied to the soil surface on the plant nutritio...Tropical soils are usually highly acidic and this may hamper mango trees nutrition and production. The objective of this work was to evaluate the effects of lime doses applied to the soil surface on the plant nutritional status, the production, and the technological quality of mango fruits. The study was carried out at Selviria, in the state of Mato Grosso, Brazil, in a Typic Haplustox. Thirteen year old producing mango plants of the “Heden” variety, grafted on rootstock of the “Coquinho” variety, were used in this experiment. Lime doses of 0, 1.55, 3.10, 4.655, and 6.20 t ha–1 were applied to the soil. Each treatment was replicated 4 times and the experimental units distributed according to a randomized complete block design. Lime (CaO: 390 g kg–1;MgO: 130 g kg–1) was superficially applied to the soil and then incorporated at depths between 0 and 5 cm in the total area of the orchard. The soil chemical characteristics pH, Ca, Mg, K, sum of bases, and bases saturation, in the 0 - 20 cm layer, were evaluated 16 and 28 months after soil liming. Plant nutritional status was evaluated 12 months after soil liming. Fruit production and technological quality were evaluated during the cropping years of 2006 and 2007. Soil liming had a positive effect on the evaluated soil chemical characteristics and this improved plant nutritional status and fruit technological quality as well as increased fruit production. These beneficial effects though were observed only in the second year after soil liming. The highest fruit production was verified when soil bases saturation was of 72% and the contents of Ca and Mg were of 32 and 8 g kg–1, respectively.展开更多
As a macronutrient,Phosphorus(P)takes many roles in plant growth and development.It should be significant to explore the molecular mechanism of low-phosphorus stress response of plants.Phosphate starvation response(PH...As a macronutrient,Phosphorus(P)takes many roles in plant growth and development.It should be significant to explore the molecular mechanism of low-phosphorus stress response of plants.Phosphate starvation response(PHR)transcription factors play important roles in response to phosphorus deficiency stress in plants.In this study,we isolated a gene related to the plant phosphorus signaling system from the acid-soil-resistant centipedegrass(Eremochloa ophiuroides[Munro]Hack.),termed EoPHR2.The subcellular localization of EoPHR2 protein was observed to be nuclear located.The expression patterns of EoPHR2 in different tissues and Al/Pi-stress conditions were analyzed by qRT-PCR,they suggested a potential role in response to the multiple-stress under acid soil adversity.Based on the functional identification through transgenic plants,we found that(1)EoPHR2 is involved in the Pi-signaling pathway,and(2)overexpression of EoPHR2 mimics Pi-starvation signalling resulting on enhanced roots whether under Pi-deficiency stress or not.In conclusion,EoPHR2 transcription factor plays a role in response to the multiple stresses under acid soil conditions,improving the low-phosphorus stress resistance of Eremochloa ophiuroides.展开更多
Electrochemical experiments,slow strain rate tensile testing(SSRT),and scanning electron microscopy were used to investigate the effect of various applied potentials on the stress corrosion cracking(SCC)of X80 pipelin...Electrochemical experiments,slow strain rate tensile testing(SSRT),and scanning electron microscopy were used to investigate the effect of various applied potentials on the stress corrosion cracking(SCC)of X80 pipeline steel in acidic soil containing sulfate-reducing bacteria(SRB).The results demonstrated that when the anodic potential was applied,X80 steel exhibited sensitivity to SCC,which was attributed to anodic dissolution.The SCC sensitivity initially decreased,but then increased with a negative shift in the applied potential.At-1200 mV,SCC was the most sensitive,which corresponded to the substantial cathodic polarisation and toxic impact of SRB,which increased the risk of hydrogen embrittlement.At-850 mV,the SCC sensitivity was the lowest because cathodic polarisation suppressed anodic dissolution.The experimental results can contribute to the prevention and management of SCC in operational pipelines.展开更多
High nitrate leaching has been observed from the O horizons of some tropical forests;however,the drivers of high nitrate production(active nitrification)in these O horizons have not yet been identified.This study inve...High nitrate leaching has been observed from the O horizons of some tropical forests;however,the drivers of high nitrate production(active nitrification)in these O horizons have not yet been identified.This study investigated the drivers of active nitrification in the O horizon of tropical forest soils by focusing on two of the most widely recognized controlling factors of nitrification,total N,and pH.We collected mineral and O horizons from eight tropical forests in Cameroon,Indonesia,and Malaysia and measured gross nitrification rates.Some O horizons showed significantly higher gross nitrification rates than mineral horizons,indicating that these O horizons have a high potential for nitrification.Gross nitrification rates in the O horizons were positively correlated with both total N and pH,and the chemical properties(e.g.,total content of N,P,and base cations)were intercorrelated.These correlations suggested that the underlying driver of nitrification in the O horizon was nutrient richness in the litter.Results also indicated a threshold of gross nitrification rates around pH values of 5.5–6.0.We elucidate that active nitrification and subsequent high nitrate leaching from the O horizon could be driven by nutrient-rich litter,possibly derived from soil fertility and tree species.展开更多
Subsoil acidity restricts root growth and reduces crop yields in many parts of the world. More than half of the fertilizer nitrogen(N) applied in crop production is currently lost to the environment. This study aimed ...Subsoil acidity restricts root growth and reduces crop yields in many parts of the world. More than half of the fertilizer nitrogen(N) applied in crop production is currently lost to the environment. This study aimed to investigate the effect of gypsum application on the efficiency of N fertilizer in no-till corn(Zea mays L.) production in southern Brazil. A field experiment examined the effects of surface-applied gypsum(0, 5, 10, and 15 Mg ha^(-1)) and top-dressed ammonium nitrate(NH_4NO_3)(60, 120, and 180 kg N ha^(-1)) on corn root length, N uptake, and grain yield. A greenhouse experiment was conducted using undisturbed soil columns collected from the field experiment site to evaluate NO_3-N leaching, N uptake, and root length with surface-applied gypsum(0 and 10 Mg ha^(-1)) and top-dressed NH_4NO_3(0 and 180 kg N ha^(-1)). Amelioration of subsoil acidity due to gypsum application increased corn root growth,N uptake, grain yield, and N use efficiency. Applying gypsum to the soil surface increased corn grain yield by 19%–38% and partial factor productivity of N(PFPN) by 27%–38%, depending on the N application rate. Results of the undisturbed soil column greenhouse experiment showed that improvement of N use efficiency by gypsum application was due to the higher N uptake from NO_3-N in the subsoil as a result of increased corn root length. Our results suggest that ameliorating subsoil acidity with gypsum in a no-till corn system could increase N use efficiency, improve grain yield, and reduce environmental risks due to NO_3-N leaching.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.
文摘Due to historical and ongoing industrial practices, lead contamination in urban soils presents substantial health risks, primarily due to its capacity to readily migrate from the soil to humans. This research focused on the influence of soil pH, organic matter, and clay content on extractable lead amounts. Sixty-four soil samples from Muncie, Indiana, were analyzed, revealing that the examined factors accounted for 21.71% of the Pb mg/Kg-dry variable variance (p −0.4, p < 0.001), with XRD and FTIR analyses confirming the binding affinity of clay minerals with lead. In contrast, no significant relationships were found between Pb concentrations and soil pH (r = 0.07;p = 0.59) or organic matter content (r = 0.12;p = 0.34). Elucidating the interactions between lead, clay minerals, and other soil constituents is crucial for addressing lead-contaminated soils and reducing environmental and health impacts.
基金supported by the grants from Indian Council of Agricultural Research (Grant No. C30033/415101-036)Department of Biotechnology,Government of India (Grant No. BT/566/NE/U-excel/2016/72)+1 种基金supported by Rajiv Gandhi National FellowshipNational Fellowship for Higher Education of ST Students (Grant No. 201516-NFST-2015-17-ST-3514), respectively, from the Ministry of Tribal Affairs, University Grant Commission, Government of India。
文摘With the hypothesis that iron(Fe) deficiency responsive genes may play a role in Fe toxicity conditions,we studied five such genes OsNAS1,OsNAS3,OsIRO2,OsIRO3 and OsYSL16 across six contrasting rice genotypes for expression under high Fe and low phosphorus(P) conditions,and sequence polymorphism.Genotypes Sahbhagi Dhan,Chakhao Poirieton and Shasharang were high yielders with no bronzing symptom visible under Fe toxic field conditions,and BAM350 and BAM811 were low yielders but did not show bronzing symptoms.Hydroponic screening revealed that the number of crown roots and root length can be traits for consideration for identifying Fe toxicity tolerance in rice genotypes.Fe contents in rice roots and shoots of a high-yielding genotype KMR3 showing leaf bronzing were significantly high.In response to 24 h high Fe stress,the expression levels of OsNAS3 were up-regulated in all genotypes except KMR3.In response to 48 h high Fe stress,the expression levels of OsNAS1 were3-fold higher in tolerant Shasharang,whereas in KMR3,it was significantly down-regulated.Even in response to 7 d excess Fe stress,the transcript abundances of OsIRO2 and OsNAS3 were contrasting in genotypes Shasharang and KMR3.This suggested that the reported Fe deficiency genes had a role in Fe toxicity and that in genotype KMR3 under excess Fe stress,there was disruption of metal homeostasis.Under the 48 h low P conditions,OsIRO2 and OsYSL16 were significantly up-regulated in Fe tolerant genotype Shasharang and in low P tolerant genotype Chakhao Poirieton,respectively.In silico sequence analysis across 3 024 rice genotypes revealed polymorphism for 4 genes.Sequencing across OsIRO3and OsNAS3 revealed nucleotide polymorphism between tolerant and susceptible genotypes for Fe toxicity.Non-synonymous single nucleotide polymorphisms and insertion/deletions(InDels) differing in tolerant and susceptible genotypes were identified.A marker targeting 25-bp InDel in OsIRO3,when run on a diverse panel of 43 rice genotypes and a biparental population,was associated with superior performance for yield under acidic lowland field conditions.This study highlights the potential of one of the vital genes involved in Fe homeostasis as a genic target for improving rice yield in acidic soils.
基金supported by the National Natural Science Foundation of China(31861133018,41830751,42107320)the Hainan University Startup Fund,China(KYQD(ZR)-20098).
文摘The inhibition of nitrification by mixing nitrification inhibitors(NI)with fertilizers is emerging as an effective method to reduce fertilizer-induced nitrous oxide(N_(2)O)emissions.The additive 3,4-dimethylpyrazole phosphate(DMPP)apparently inhibits ammonia oxidizing bacteria(AOB)more than ammonia oxidizing archaea(AOA),which dominate the nitrification in alkaline and acid soil,respectively.However,the efficacy of DMPP in terms of nitrogen sources interacting with soil properties remains unclear.We therefore conducted a microcosm experiment using three typical Chinese agricultural soils with contrasting pH values(fluvo-aquic soil,black soil and red soil),which were fertilized with either digestate or urea in conjunction with a range of DMPP concentrations.In the alkaline fluvo-aquic soil,fertilization with either urea or digestate induced a peak in N_(2)O emission(60μg N kg^(-1)d^(-1))coinciding with the rapid nitrification within 3 d following fertilization.DMPP almost eliminated this peak in N_(2)O emission,reducing it by nearly 90%,despite the fact that the nitrification rate was only reduced by 50%.In the acid black soil,only the digestate induced an N_(2)O emission that increased gradually,reaching its maximum(20μg N kg^(-1)d^(-1))after 5–7 d.The nitrification rate and N_(2)O emission were both marginally reduced by DMPP in the black soil,and the N_(2)O yield(N_(2)O-N per NO2–+NO3–-N produced)was exceptionally high at 3.5%,suggesting that the digestate induced heterotrophic denitrification.In the acid red soil,the N_(2)O emission spiked in the digestate and urea treatments at 50 and 10μg N kg^(-1)d^(-1),respectively,and DMPP reduced the rates substantially by nearly 70%.Compared with 0.5%DMPP,the higher concentrations of DMPP(1.0 to 1.5%)did not exert a significantly(P<0.05)better inhibition effect on the N_(2)O emissions in these soils(either with digestate or urea).This study highlights the importance of matching the nitrogen sources,soil properties and NIs to achieve a high efficiency of N_(2)O emission reduction.
基金financially supported by the National Natural Science Foundation of China (32072661)the National Key Research and Development Program of China(2021YFF1000500)。
文摘Acid soils occupy approximately 50% of potentially arable lands.Improving crop productivity in acid soils,therefore,will be crucial for ensuring food security and agricultural sustainability.High soil acidity often coexists with phosphorus(P) deficiency and aluminum(Al) toxicity,a combination that severely impedes crop growth and yield across wide areas.As roots explore soil for the nutrients and water required for plant growth and development,they also sense and respond to below-ground stresses.Within the terrestrial context of widespread P deficiency and Al toxicity pressures,plants,particularly roots,have evolved a variety of mechanisms for adapting to these stresses.As legumes,soybean(Glycine max) plants may acquire nitrogen(N) through symbiotic nitrogen fixation(SNF),an adaptation that can be useful for mitigating excessive N fertilizer use,either directly as leguminous crop participants in rotation and intercropping systems,or secondarily as green manure cover crops.In this review,we investigate legumes,especially soybean,for recent advances in our understanding of root-based mechanisms linked with root architecture modification,exudation and symbiosis,together with associated genetic and molecular strategies in adaptation to individual and/or interacting P and Al conditions in acid soils.We propose that breeding legume cultivars with superior nutrient efficiency and/or Al tolerance traits through genetic selection might become a potentially powerful strategy for producing crop varieties capable of maintaining or improving yields in more stressful soil conditions subjected to increasingly challenging environmental conditions.
基金Supported by Science and Technology Program Major Project of Yunnan Branch,China National Tobacco Corporation(2020530000241022)。
文摘[Objectives]This study was conducted to improve acidic soil and enhance the quality of tobacco leaves.[Methods]The effects of different microbial fertilizers on improving acidic tobacco-planting soil and tobacco leaf quality were investigated through plot experiments.[Results]The application of microbial fertilizers could improve the pH value of acidic soil,and composite microbial agent A showed the best application effect.The application of bio-organic fertilizer was beneficial to improving the contents of available phosphorus and available boron in acidic soil.The application of composite microbial agent A was beneficial to improving the contents of available phosphorus and available potassium in acidic soil,and could promote the growth of tobacco plants and improve the economic traits of flue-cured tobacco and the coordination of chemical components in tobacco leaves.The application of composite microbial agent B led to a downward trend in the content of available boron in acidic soil.The application of composite microbial agent B could promote the absorption of nutrients by tobacco plants,and improve their disease resistance and the quality of tobacco leaves.Due to the differences in functional microorganisms contained,the application effects of different microbial fertilizers in improving acidic tobacco-planting soil and improving tobacco leaf quality varied.Overall,the application of microbial fertilizers could increase soil pH,activate soil nutrients,promote tobacco growth,enhance disease resistance,increase tobacco output value,and improve tobacco quality.Microbial fertilizers have good application prospects in improving acidic soil and improving tobacco quality.[Conclusions]The application of microbial fertilizers to improve acidic tobacco-planting soil can ensure the normal growth and development of tobacco plants and the improvement of tobacco leaf quality,achieving high-quality and sustainable development of Zhaotong tobacco.
文摘This study is a contribution to improving rice productivity on acidic plateau soils of the tropical rainforest zone. It is based on taking into account the cationic balances of the soil in order to optimize the phosphorus (P) nutrition of rice on these acidic soils, where this nutrient constitutes a limiting factor for agricultural production. Three (3) pot trials were conducted in Adiopodoumé in the forested south of Côte d’Ivoire. The interactive effects of calcium carbonate (0, 25, 50 and 75 kg Ca ha<sup>−1</sup>) and magnesium sulfate (0, 25, 50 and 75 kg Mg ha<sup>−1</sup>) were evaluated on the response of NERICA 5 rice at doses 0, 25, 50 and 75 kg P ha<sup>−1</sup> of natural phosphate from Togo, applied only once at the start of the experiment. Additional fertilizers of nitrogen (N) (100 kg N ha<sup>−1</sup>) and potassium (K) (50 kg KCl ha<sup>−1</sup>) were added to each of the tests in a split-plot device. The test results revealed a paddy production potential of approximately 3 to 5 t⋅ha<sup>−1</sup> for NERICA 5 on an acidic soil, under the effect of the interaction of P, Ca and Mg. The quadratic response of rice yield to the doses of these fertilizers would be more dependent on their balance, itself influenced by Ca nutrition. For the sustainability and maintenance of rice production in agro-ecology studied, it was recommended doses of 38 kg Ca ha<sup>−1</sup>, 34 kg Mg ha<sup>−1</sup> in a Ca/Mg ratio (1/1) with intakes of 41 kg P ha<sup>−1</sup>, overall in a ratio 1/1/1 (P/Ca/Mg) more favorable to the availability of free iron considered a guiding element of mineral nutrition. Thus, these promising results should be confirmed in a real environment for better management of the fertilization of rice cultivated on acidic plateau soils in Côte d’Ivoire.
文摘Phosphorus bioavailability has long been a recurring problem in tropical acid soils. A pot experiment was carried out during three (3) successive rice production cycles at Adiopodoumé to evaluate the response of the NERICA 5 rice accession to various doses of calcium, magnesium and phosphorous. The experiment was conducted using a randomized split-plot design. The interactive effects of calcium carbonate (0, 25, 50 and 75 kg·Ca·ha<sup>-1</sup>) and magnesium sulfate (0, 25, 50 and 75 kg·Mg·ha<sup>-1</sup>) and Togo natural phosphate (0, 25, 50 and 75 kg·P·ha<sup>-1</sup>) were determined at each production cycle. The results showed that single-dose natural phosphate supplementation for three cropping cycles resulted in an average enrichment of around 2 mg·P·kg<sup>-1</sup> after each trial following its continuous dissolution, with an increase in DSP (33.31% to 70.52%). The study revealed one strategy for managing and enhancing native P with cations and another for exogenous P: there would be a synergy of Ca/Mg on native P, whereas an antagonism would characterize the two parameters in phosphate fertilization.
文摘Soil aluminum phytotoxicity has been a major research area since the inception of modern soil science. Acid soils, which typically manifest plant aluminum toxicity, are frequently dedicated to food production, thus yield and quality reductions influence food security. This manuscript reviews our modern understanding of 1) soil aluminum hydrolysis and polymerization, 2) aluminum complexation with inorganic and organic anions, 3) aluminum interference with vital plant physiological processes, 4) aluminum and forest ecosystem productivity, and 5) demonstrates the software simulation of aluminum reactivity and its role in predicting soil behavior. The manuscript also provides a perspective for future soil-aluminum research critical to maintaining food security and food quality.
文摘The popularization of <i>Dioscorea dumetorum</i> (Dioscoreaceae), a nutritious yam species is still marginal due to constraints such as the low interest of research, poor cultural practices, insufficient and expensive seeds, pests, and diseases. The latter pushes producers to use about 50% of their harvest as seed for the next planting season. The lack of a specific fertilizer formulation for yam production on the oxysols of Cameroon is another constraint. This study was aimed at enhancing the availability of quality seeds through the characterization of five yam accessions. One experiment was performed to determine the effect of cultivar and origin of tuber sets on their germination rate. The <span>second concerned the evaluation of cultivars and soil treatment effects on ag</span>ronomic parameters of yam seedlings. Yam cultivars were subjected to nine fertilizer formulations as follows: T0: no fertilizer;T1: mycorrhizal fungi (MF) + 150 g manure + peanut waste;T2: 25 g chemical fertilizer (20.10.10);T3: MF + peanut waste;T4: 16 g chemical fertilizer (12.6.20);T5: 25 g (20.10.10) +100 g CaO + 150 g manure;T6: 100 g CaO + 150 g manure;T7: 20 g tropicote + 2 g DAP (Diammonium phosphate, a reference starter fertilizer coded N18P46) + 100 g CaO + 150 g manure;and T8: mycorrhiza. These treatments were tested in a factorial design. Results show that Ibo sweet 3 and Mabondji sweet white 1 yam accessions were less affected by anthracnose disease on the aerial parts. Guzang 1 showed the best germination rate and yield, making it appropriate for cultivation in the region. Soil treatments, T2, T5, T7 and T8 significantly increased the yield of yam cultivars. Mycorrhiza treatment alone gave a better response to seed weight, indicating the interest of this biofertilizer as a solution for good seedling production. These fertilizer treatments can be recommended to farmers for more seed production with optimum seed weight (300 g).
文摘Ferralsols form a dominant type of soil on which most crops are grown in the Lake Victoria agro-ecological zone. Soil acidity has been recognized among the most important agricultural problems in such soils, which adversely affect crop production and productivity. A study was conducted with the objective of determining the effect of applying low rates of lime and chicken manure on selected soil chemical properties. Using a Split Plot Factorial Randomized Complete Block Design, agricultural lime (0.0, 0.5, 1.0, 1.5 & 2.0 t·ha<sup>-1</sup>) as the main plot and chicken manure (0.0, 1.0, 2.0 & 3.0 t·ha<sup>-1</sup>) as sub-plot were applied, replicated three times. The test crop was common bean var. NABE 15. The experiment was conducted for three rainy seasons, two seasons on-station and one season on-farm on Ferralsol soil in the Lake Victoria crescent of central Uganda. The results showed that applying low rates of lime with chicken manure significantly (p ·ha<sup>-1</sup> lime was applied with the four chicken manure rates in Mukono. From the study, we recommend the application of small quantities of lime at 1.0 t·ha<sup>-1</sup> with either 2.0 or 3.0 t·ha<sup>-1</sup> chicken manure.
文摘This paper described the use of fy ash for soil amelioration of acidic soils to promote plant growth.In mining sites,acid sulfate soils/rocks,which contain sulfde minerals(e.g.pyrite FeS_(2)),have appeared as a result of overburden excavation.The excessively acidic condition inhibits plant growth due to the dissolution of harmful elements,such as Al,Fe,and Mn.Fly ash,an alkaline byproduct of coal combustion generated in thermal power plants is expected to be adopted to ameliorate acidic soils.However,the mixing ratio of fy ash must be considered because excessive addition of fy ash can have a negative impact on plant growth due to its physical/chemical properties.The pot trials using Acacia mangium demonstrate the evolution of plant growth with a 5%–10%addition of fy ash into acidic soil.When the acidic soil has a high potential for metal dissolution,the metal ions leached from the acidic soil are large,making it difcult to improve plant growth due to osmotic and ionic stress.This work suggests that the efects of fy ash on metal ions leached from the soil have to be considered for the amelioration of acidic soil.
文摘Cation exchange capacity (CEC) is one of the most important properties of soils. The NH<sub>4</sub>OAc (pH = 7.0) exchange method is usually recommended to determine CEC (CEC<sub>1</sub>) of all soils with different pH values, particularly for studies on soil taxonomy. But comparatively the BaCl<sub>2</sub>-MgSO<sub>4</sub> forced-exchange method is more authentic in determining CEC (CEC<sub>2</sub>) of tropical and subtropical highly-weathered acid soils. But so far little is known about the difference between CEC<sub>1</sub> and CEC<sub>2</sub>. In this study, the physiochemical data of 114 acid B horizon soils from 112 soil series of tropical and subtropical China were used, CEC<sub>1</sub> and CEC<sub>2</sub> were determined and compared, the influencing factors were analyzed for the difference between CEC<sub>1</sub> and CEC<sub>2</sub>, and then a regression model was established between CEC<sub>1</sub> and CEC<sub>2</sub>. The results showed that CEC<sub>2</sub> was significantly lower than CEC<sub>1</sub> (p < 0.01), CEC<sub>2</sub> was 14.76% - 63.31% with a mean of 36.32% of CEC<sub>1</sub>. In view of the contribution to CEC from other properties, CEC<sub>2</sub> was mainly determined by pH (45.92%), followed by silt (21.05%), free Fe<sub>2</sub>O<sub>3</sub> (17.35%) and clay contents (12.76%), CEC<sub>1</sub> was mainly decided by free Fe<sub>2</sub>O<sub>3</sub> content (40.38%), followed by pH (28.39%) and silt content (27.29%;and the difference between CEC<sub>1</sub> and CEC<sub>2</sub> was mainly affected by free Fe<sub>2</sub>O<sub>3</sub> (50.92%), followed by silt content (26.46%) and pH (21.80%). The acceptable optimal regression model between CEC<sub>2</sub> and CEC<sub>1</sub> was established as CEC<sub>2</sub> = 2.3114 × CEC<sub>1</sub><sup>1.1496</sup> (R<sup>2</sup> = 0.410, P < 0.001, RMSE = 0.15). For the studies on soil taxonomy, the BaCl<sub>2</sub>-MgSO<sub>4</sub> forced-exchange method is recommended in determining CEC of the highly-weathered acid soils in the tropical and subtropical regions.
基金supported by the National Natural Science Foundation of China (31570599 and 32171753)。
文摘Plant tolerance to aluminum(Al)toxicity can be enhanced by an ectomycorrhizal(ECM)fungus through biological filtering or physical blockage.To understand the roles of ECM colonization in Al absorption with regard to Al tolerance,Pinus massoniana seedlings were inoculated with either Lactarius deliciosus(L.:Fr.)Gray isolate 2 or Pisolithus tinctorius(Pers.)Coker et Couch isolate 715 and cultivated in an acid yellow soil with or without 1.0 mM Al^(3+)irrigation for 10 weeks.Biomass production,Al bioaccumulation and transport in seedlings colonized by the two ECM fungi were compared,and the three absorption kinetics(pseudo-first order,pseudo-second order and intraparticle diffusion)models used to evaluate variances in root Al^(3+)absorption capacity.Results show that both fungi increased aboveground biomass and Al tolerance of P.massoniana seedlings,but L.deliciosus 2 was more effective than P.tinctorius 715.Lower Al absorption capacity,fewer available active sites and decreased affinity and boundary layer thickness for Al^(3+),and higher Al accumulation and translocation contributed to the increased Al tolerance in the ECM-inoculated seedlings.These results advance our understanding of the mechanisms and strategies in plant Alto lerance conferred by ECM fungi and show that inoculation with L.deliciosus will better enhance Al tolerance in P.massoniana seedlings used for forest plantation and ecosystem restoration in acidic soils,particularly in Southwest China and similar soils worldwide.
文摘Soil acidification and phosphorus deficiency are a major constraint to crop production in tropical soils.Use of conventional liming materials is associated with some limitations viz:inability to solely improve nitrogen and available phosphorus in soils,loss of soil organic carbon and soil aggregate stability.Liming and fertilizer potentials of leaves from three plant materials(Tithonia diversifolia(TL),Imperata cylindrica(SG)and Gliricidia sepium(GL))widely growing in Ogbomoso,southwest Nigeria,were tested under incubation condition.Each of the plant material was applied at the rate of 10 t·hm^(-2) with and without 50%concentration of NPK 15:15:15-urea mix in 500 g acidic soil.Sole lime applied at 1 t·hm^(-2),sole NPK 15:15:15 applied at 60 kg·hm^(-2) mixed with urea at 60 kg N·hm^(-2) and an unamended soil were compared in completely randomized design in three replicates.The treated soils were incubated for 12 weeks.Thereafter,maize seeds were raised in each pot for a period of 3 weeks.Data collected were subjected to analysis of variance.Regression analysis was used to predict contributions of increased soil p H in plant material treated soils to exchangeable Al,H,dry root weight of maize and available phosphorus.Results indicated that sole plant materials were the order SG>TL>GL significantly(p<0.05)reduced exchangeable acidity compared to unamended and sole NPK.Sole NPK had the highest exchangeable acidity(4.7 cmol·kg^(-1))compared to unamended soil(3.3 cmol·kg^(-1))and sole lime(2.7 cmol·kg^(-1)).Application of sole Tithonia diversifolia increased available phosphorus by 214%and 97%compared to unamended and sole NPK treated soils respectively.Sole plant materials increased maize root weight by 33%compared to sole NPK.Increasing soil p H at harvesting in plant material treated soils significantly reduced exchangeable H and A_1.Soil p H was responsible for up to 33%and 53%reductions in exchangeable Al and H,respectively.This culminated into up to 22%increases in dry root weight of maize seedling.Present results showed ability of the plant materials tested to ameliorate soil acidity and improved soil available phosphorus.The plant materials should be explored for using as green manure and composting feedstock.It will go a long way to reduce high dosage use of conventional liming and fertilizer materials on acidic nutrient degraded soils.
文摘Tropical soils are usually highly acidic and this may hamper mango trees nutrition and production. The objective of this work was to evaluate the effects of lime doses applied to the soil surface on the plant nutritional status, the production, and the technological quality of mango fruits. The study was carried out at Selviria, in the state of Mato Grosso, Brazil, in a Typic Haplustox. Thirteen year old producing mango plants of the “Heden” variety, grafted on rootstock of the “Coquinho” variety, were used in this experiment. Lime doses of 0, 1.55, 3.10, 4.655, and 6.20 t ha–1 were applied to the soil. Each treatment was replicated 4 times and the experimental units distributed according to a randomized complete block design. Lime (CaO: 390 g kg–1;MgO: 130 g kg–1) was superficially applied to the soil and then incorporated at depths between 0 and 5 cm in the total area of the orchard. The soil chemical characteristics pH, Ca, Mg, K, sum of bases, and bases saturation, in the 0 - 20 cm layer, were evaluated 16 and 28 months after soil liming. Plant nutritional status was evaluated 12 months after soil liming. Fruit production and technological quality were evaluated during the cropping years of 2006 and 2007. Soil liming had a positive effect on the evaluated soil chemical characteristics and this improved plant nutritional status and fruit technological quality as well as increased fruit production. These beneficial effects though were observed only in the second year after soil liming. The highest fruit production was verified when soil bases saturation was of 72% and the contents of Ca and Mg were of 32 and 8 g kg–1, respectively.
基金This work was supported by the National Natural Science Foundation of China(Grant No.31902046)the National Natural Science Foundation of China(Grant No.32072608)+1 种基金the National Natural Science Foundation of China(Grant No.31902060)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20180315),and the Foundation of Jiangsu Key Laboratory for the Research and Utilization of Plant Resources(Institute of Botany,Jiangsu Province and Chinese Academy of Sciences).
文摘As a macronutrient,Phosphorus(P)takes many roles in plant growth and development.It should be significant to explore the molecular mechanism of low-phosphorus stress response of plants.Phosphate starvation response(PHR)transcription factors play important roles in response to phosphorus deficiency stress in plants.In this study,we isolated a gene related to the plant phosphorus signaling system from the acid-soil-resistant centipedegrass(Eremochloa ophiuroides[Munro]Hack.),termed EoPHR2.The subcellular localization of EoPHR2 protein was observed to be nuclear located.The expression patterns of EoPHR2 in different tissues and Al/Pi-stress conditions were analyzed by qRT-PCR,they suggested a potential role in response to the multiple-stress under acid soil adversity.Based on the functional identification through transgenic plants,we found that(1)EoPHR2 is involved in the Pi-signaling pathway,and(2)overexpression of EoPHR2 mimics Pi-starvation signalling resulting on enhanced roots whether under Pi-deficiency stress or not.In conclusion,EoPHR2 transcription factor plays a role in response to the multiple stresses under acid soil conditions,improving the low-phosphorus stress resistance of Eremochloa ophiuroides.
基金the Joint Fund of Natural Science Foundation of Liaoning Province(Grant No.2020-HYLH-14)the Natural Science Foundation of Liaoning Province(2022-MS-362)。
文摘Electrochemical experiments,slow strain rate tensile testing(SSRT),and scanning electron microscopy were used to investigate the effect of various applied potentials on the stress corrosion cracking(SCC)of X80 pipeline steel in acidic soil containing sulfate-reducing bacteria(SRB).The results demonstrated that when the anodic potential was applied,X80 steel exhibited sensitivity to SCC,which was attributed to anodic dissolution.The SCC sensitivity initially decreased,but then increased with a negative shift in the applied potential.At-1200 mV,SCC was the most sensitive,which corresponded to the substantial cathodic polarisation and toxic impact of SRB,which increased the risk of hydrogen embrittlement.At-850 mV,the SCC sensitivity was the lowest because cathodic polarisation suppressed anodic dissolution.The experimental results can contribute to the prevention and management of SCC in operational pipelines.
基金This study was supported by Center for Ecological Research,Kyoto University,a Joint Usage/Research Center,and financially supported by the Japan Society for the Promotion of Science(JSPS)KAKENHI(Grant numbers 24228007,17H06171,and 19J14572).The authors have no relevant financial or non-financial interests to disclose.
文摘High nitrate leaching has been observed from the O horizons of some tropical forests;however,the drivers of high nitrate production(active nitrification)in these O horizons have not yet been identified.This study investigated the drivers of active nitrification in the O horizon of tropical forest soils by focusing on two of the most widely recognized controlling factors of nitrification,total N,and pH.We collected mineral and O horizons from eight tropical forests in Cameroon,Indonesia,and Malaysia and measured gross nitrification rates.Some O horizons showed significantly higher gross nitrification rates than mineral horizons,indicating that these O horizons have a high potential for nitrification.Gross nitrification rates in the O horizons were positively correlated with both total N and pH,and the chemical properties(e.g.,total content of N,P,and base cations)were intercorrelated.These correlations suggested that the underlying driver of nitrification in the O horizon was nutrient richness in the litter.Results also indicated a threshold of gross nitrification rates around pH values of 5.5–6.0.We elucidate that active nitrification and subsequent high nitrate leaching from the O horizon could be driven by nutrient-rich litter,possibly derived from soil fertility and tree species.
基金supported by CNPq(Conselho Nacional de Desenvolvimento Científico e Tecnológico),BrazilCAPES(Coordenacao de Aperfeicoamento de Pessoal de Nível Superior),Brazil
文摘Subsoil acidity restricts root growth and reduces crop yields in many parts of the world. More than half of the fertilizer nitrogen(N) applied in crop production is currently lost to the environment. This study aimed to investigate the effect of gypsum application on the efficiency of N fertilizer in no-till corn(Zea mays L.) production in southern Brazil. A field experiment examined the effects of surface-applied gypsum(0, 5, 10, and 15 Mg ha^(-1)) and top-dressed ammonium nitrate(NH_4NO_3)(60, 120, and 180 kg N ha^(-1)) on corn root length, N uptake, and grain yield. A greenhouse experiment was conducted using undisturbed soil columns collected from the field experiment site to evaluate NO_3-N leaching, N uptake, and root length with surface-applied gypsum(0 and 10 Mg ha^(-1)) and top-dressed NH_4NO_3(0 and 180 kg N ha^(-1)). Amelioration of subsoil acidity due to gypsum application increased corn root growth,N uptake, grain yield, and N use efficiency. Applying gypsum to the soil surface increased corn grain yield by 19%–38% and partial factor productivity of N(PFPN) by 27%–38%, depending on the N application rate. Results of the undisturbed soil column greenhouse experiment showed that improvement of N use efficiency by gypsum application was due to the higher N uptake from NO_3-N in the subsoil as a result of increased corn root length. Our results suggest that ameliorating subsoil acidity with gypsum in a no-till corn system could increase N use efficiency, improve grain yield, and reduce environmental risks due to NO_3-N leaching.
