Alteration of soil pH induced by submerging/drainage and application of peanut straw biochar and its impact on Cd(II) availability in an acidic soil to indica-japonica rice varieties.

The effects of soil pH variations induced by submergence/drainage and biochar application on soil cadmium (Cd) availability to different rice (Oryza sativa L.) varieties are not well understood. This study aims to investigate the possible reasons for available Cd(II) reduction in paddy soil as influenced by biochar and to determine Cd(II) absorption and translocation rates in different parts of various rice varieties.

Combined application of Pseudomonas fluorescens and urea can mitigate rapid acidification of cropland Ultisol.

Rhizobacteria maintain a healthy soil required for crop growth. This has led to increased interest in the use of bacteria-based biofertilizers in agriculture as they improve soil nutrient content and protect plants against pathogens. However, the effect of bacteria inoculum on N transformation and soil physicochemical properties during urea fertilization remains unexploited.

Dissolved biochar fractions and solid biochar particles inhibit soil acidification induced by nitrification through different mechanisms.

Biochar can inhibit soil acidification by decreasing the H input from nitrification and improving soil pH buffering capacity (pHBC). However, biochar is a complex material and the roles of its different components in inhibiting soil acidification induced by nitrification remain unclear. To address this knowledge gap, dissolved biochar fractions (DBC) and solid biochar particles (SBC) were separated and mixed thoroughly with an amended Ultisol.

More negative charges on roots enhanced manganese(II) uptake in leguminous and non-leguminous poaceae crops.

Background: Manganese (Mn) is an essential micronutrient for plants, whereas excess Mn(II) in soils leads to its toxicity to crops. Mn(II) is adsorbed onto plant roots from soil solution and then absorbed by plants. Root charge characteristics should affect Mn(II) toxicity to crops and Mn(II) uptake by the roots of the crops.

The mechanism for enhancing phosphate immobilization on colloids of oxisol, ultisol, hematite, and gibbsite by chitosan.

Phosphorus (P) availability in highly weathered soils is significantly influenced by the contents of iron (Fe)/aluminum (Al) oxides, clay minerals, and organic matter. With the increasing interest in biofertilizers (e.g.

Inhibition of phosphate sorptions on four soil colloids by two bacteria.

Ion sorption on soil and sediment has been reported to be potentially affected by bacteria which may interact both physically and chemically with solid surfaces. However, whether and how bacteria affect the sorption of inorganic phosphate (P) on soil colloids remains poorly known. Here, we comparably investigated the P sorption on four soil colloids (three highly weathered soils including two Oxisols and one Ultisol and one weakly weathered soil Alfisol) and their complexes with Bacillus subtilis and Pseudomonas fluorescens.

Effect of root surface charge on the absorption and accumulation of Cu(II) by different japonica and indica rice varieties under acidic conditions.

Excessive amounts of copper (Cu) in soils causes toxic effects on plants. In this study, 58 rice cultivars were classified into tolerant, moderately tolerant, and susceptible types for Cu(II) toxicity based on 50% germination (LC). Nine japonica rice varieties (three each from the tolerant, moderately tolerant, and susceptible groups) and six indica rice varieties (three from the moderately tolerant and susceptible groups) were selected for the hydroponics experiments.

Application of measuring electrochemical characteristics on plant root surfaces in screening Al-tolerant wheat.

To explore the relationship between Al phytotoxicity and the electrochemical characteristics of wheat root surfaces, a new chemical mechanism for tolerance of wheat to Al toxicity was initially proposed by conducting acute root elongation experiment, adsorption/desorption experiment, streaming potential determination, and infrared spectroscopy (ATR-FTIR) analysis respectively to classify the grade of Al tolerance of 92 wheat cultivars and quantitatively characterize the electrochemical properties of their root surfaces. Then a pot experiment was conducted with the screened wheat cultivars with different Al resistance grown on acid soils to verify their tolerance to Al toxicity. Results show that zeta potentials of the roots of 67 wheat cultivars at pH4.

Plants alter surface charge and functional groups of their roots to adapt to acidic soil conditions.

The rapid increase in soil acidification rate has led to a decrease in global agricultural productivity owing to the debilitating effects of Al and Mn toxicities. In this study, we investigated the adaptation of plants to acidic conditions by examining the behavior of plant roots grown in hydroponic solution and pot experiments at different pHs. The Mn(II) sorption by the roots was investigated and the mechanisms involved were deduced by analyzing the changes in the zeta potential and functional groups on the root surface.

Effects of surface charge and chemical forms of manganese(II) on rice roots on manganese absorption by different rice varieties.

The roots of 4 japonica, 4 indica, and 7 hybrid rice varieties were obtained by hydroponic experiment and used to explore the relationship between charge characteristics and exchangeable manganese(II) (Mn(II)) on rice roots and Mn(II) absorption in roots and shoots of the rice. Results indicated Mn(II) adsorbed on rice roots mainly existed as exchangeable Mn(II) after 2 h. The roots of indica and hybrid rice carried more negative charges than the roots of japonica rice.

Effects of crop straw biochars on aluminum species in soil solution as related with the growth and yield of canola (Brassica napus L.) in an acidic Ultisol under field condition.

The toxicity of aluminum (Al) to plants in acidic soils depends on the Al species in soil solution. The effects of crop straw biochars on Al species in the soil solution, and canola growth and yield were investigated in this study. In a long-term field experiment, there were four treatments, which were a control, rice straw biochar (RSB), canola straw biochar (CSB), and peanut straw biochar (PSB).

Periphyton has the potential to increase phosphorus use efficiency in paddy fields.

The phosphorus (P) supply is mismatched with rice demand in the early and late stages of rice growth, which primarily results in low P use efficiency and high environmental risk. In recent years, the use of the natural periphyton in nutrient regulation in paddy fields has attracted much research interest. However, a mechanistic understanding of the action of periphyton on P biogeochemical cycling during the pivotal stages of rice growth has received little attention.

Biochar retards Al toxicity to maize (Zea mays L.) during soil acidification: The effects and mechanisms.

Biochar can effectively alleviate the Al phytotoxicity in acidic soils due to its alkaline nature. However, the longevity of this alleviation effect of biochar under re-acidification conditions is still unclear. In the present study, the maize root growth responding to the simulated re-acidification of two acidic soils amended by peanut straw biochar or Ca(OH) was investigated to evaluate the long-term effect of biochar on alleviating Al toxicity in acidic soils.

Method for initially selecting Al-tolerant rice varieties based on the charge characteristics of their roots.

To explore the relationship between charge characteristics of rice roots and aluminum (Al) tolerance of rice, roots of 47 different rice genotypes were obtained by hydroponic experiment. The zeta potentials of roots were determined by streaming potential method, and the Al tolerance and the functional groups of rice were measured by relative root elongation and infrared spectroscopy (ATR-FTIR), respectively. The exchangeable, complexed and precipitated Al(III) sorbed on the root surface of rice was extracted with 1 mol L KNO, 0.

An electrokinetic perspective into the mechanism of divalent and trivalent cation sorption by extracellular polymeric substances of Pseudomonas fluorescens.

Extracellular polymeric substances (EPS) contain a vast number of functional groups which can provide sorption sites for heavy metal cations in solution, however, the mechanisms for the interaction of EPS with various metal cations were not well understood. In this study, the sorption potential of EPS from Pseudomonas fluorescens for different cations was investigated. The changes of electrokinetic properties that occurred on the surface of EPS once they adsorbed these cations were also studied using zeta potential measurements as a function of pH and cation concentration.

Beneficial dual role of biochars in inhibiting soil acidification resulting from nitrification.

The dual role of biochar for inhibiting soil acidification induced by nitrification was determined through two-step incubation experiments in this study. Ca(OH) or biochar was added respectively to adjust soil pH to the same values (pH 5.15 and 5.

Adhesion mediated transport of bacterial pathogens in saturated sands coated by phyllosilicates and Al-oxides.

The current knowledge of bacterial migration is mainly derived from work using bare or Fe-coated quartz sands as porous media. However, mineral coatings on quartz by phyllosilicates and Al-oxides prevail in natural soils, and their effect on bacterial transport remains unknown. Herein, we systematically explored the transport of two bacterial pathogens (Escherichia coli and Staphylococcus aureus) through saturated bare quartz and those coated by kaolinite (KaoQuartz), montmorillonite (MontQuartz) or Al-oxides (AlQuartz) under various solution ionic strength (IS) and pH levels.

Mechanism of Cu(II) and Cd(II) immobilization by extracellular polymeric substances (Escherichia coli) on variable charge soils.

Extracellular polymeric substances (EPS) found in soils can reduce the mobility of heavy metals through the use of both electrostatic and non-electrostatic mechanisms. Their effects vary from one soil type to another. The influence of EPS from Escherichia coli on the adsorption behaviors of Cu(II) and Cd(II) by two bulk variable charge soils, Oxisol and Ultisol, was studied at constant and varied pH, and the results were compared to a constant charge Alfisol.

Effect of different phosphorus sources on soybean growth and arsenic uptake under arsenic stress conditions in an acidic ultisol.

Soil arsenic (As) contamination is a serious concern because of its mark negative impacts on plant growth and physiological processes. In plant-soil system, As competes against phosphorus (P) which depends on charge component of different soil types. The main objective of this study was to investigate the influence of ((NH)PO (PO) and Ca(PO)(OH) (phosphorite)) in ameliorating As stress on plant physiological process against As toxicity and their role in As accumulation.

Adsorption mechanism of extracellular polymeric substances from two bacteria on Ultisol and Alfisol.

The primary objective of this study was to identify the capacity and mechanism of extracellular polymeric substance (EPS) adsorption on soil colloids of Alfisol and Ultisol at different pH and ionic strengths. Two kinds of EPS were extracted from Bacillus subtilis and Pseudomonas fluorescens by centrifugation, and their adsorption on Ultisol and Alfisol was investigated using a batch adsorption experiment and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The average diameter of EPS from B.

Preferential adhesion of surface groups of Bacillus subtilis on gibbsite at different ionic strengths and pHs revealed by ATR-FTIR spectroscopy.

Adhesion of bacteria onto minerals is a ubiquitous process that plays a central role in many biogeochemical, microbiology and environmental processes in soil and sediment. Although bacterial adhesion onto soil minerals such as phyllosilicates and Fe-oxides have been investigated extensively, little is known about the mechanisms for bacterial attachment onto Al-oxides. Here, we explored the adhesion of Bacillus subtilis onto gibbsite (γ-AlOOH) under various ionic strengths (1, 10, 50, and 100 mM NaCl) and pHs (pH 4, 7, and 9) by in-situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy.

Incorporation of corn straw biochar inhibited the re-acidification of four acidic soils derived from different parent materials.

The effect of corn straw biochar on inhibiting the re-acidification of acid soils derived from different parent materials due to increased soil pH buffering capacity (pHBC) was investigated using indoor incubation and simulated acidification experiments. The incorporation of the biochar increased the pHBC of all four soils due to the increase in soil cation exchange capacity (CEC). When 5% biochar was incorporated, the pHBC was increased by 62, 27, 32, and 24% for the Ultisols derived from Tertiary red sandstone, Quaternary red earth, granite, and the Oxisol derived from basalt, respectively.

Peanut straw biochar increases the resistance of two Ultisols derived from different parent materials to acidification: A mechanism study.

The mechanisms for increasing soil pH buffering capacity (pHBC) and soil resistance to acidification by peanut straw biochar were investigated by undertaking indoor incubation and simulated acidification experiments using two Ultisols derived from tertiary red sandstone and quaternary red earth. The biochar increased the pHBC and resistance of the two Ultisols to acidification. The addition of 3% biochar increased the pHBC of the two Ultisols by 76% and 25%, respectively.

Higher cation exchange capacity determined lower critical soil pH and higher Al concentration for soybean.

Low soil pH and aluminum (Al) toxicity induced by soil acidification are the main obstacles in many regions of the world for crop production. The purpose of this study was to reveal the mechanisms on how the properties of the soils derived from different parent materials play role on the determination of critical soil pH and Al concentration for soybean crops. A set of soybean pot experiment was executed in greenhouse with a soil pH gradient as treatment for each of four soils to fulfill the objectives of this study.