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.

Application of chitosan- and alginate-modified biochars in promoting the resistance to paddy soil acidification and immobilization of soil cadmium.

To develop more green, practical and efficient biochar amendments for acidic soils, chitosan-modified biochar (CRB) and alginate-modified biochar (ARB) were prepared, and their effects on promoting soil pH buffering capacity (pHBC) and immobilizing cadmium (Cd) in the paddy soils were investigated through indoor incubation experiments. The results of Fourier transform infrared spectroscopy and Boehm titration indicated that the introduction of chitosan and sodium alginate effectively amplified the functional groups of the biochar, and improved acid buffering capacity of the biochar. Since there was a plateau region between pH 4.

Critical values of soil solution Al activity and pH for canola and maize cultivation in two acidic soils.

Background: Aluminum (Al) toxicity caused by soil acidification is the main constraint for crop growth in tropical and subtropical areas of southern China. The critical values of soil solution Al activity and pH for crops in acidic soils can provide a useful reference for soil acidity amelioration.

Results: A pot experiment in a greenhouse was conducted to investigate the critical values of soil solution Al activity and pH for canola and maize in an Ultisol and an Alfisol.

Effects of pH variations caused by redox reactions and pH buffering capacity on Cd(II) speciation in paddy soils during submerging/draining alternation.

Incubation experiments were conducted to investigate the influencing factors of pH variation in different paddy soils during submerging/draining alternation and the relationship between pH buffering capacity (pHBC) and Cd speciation in ten paddy soils developed from different parent materials (including 8 acid paddy soils and 2 alkaline paddy soils). The soil pHBC and the changes in soil pH, Eh, Fe, Mn, SO and Cd speciation were determined. The results showed that there was a significant positive correlation between cation exchange capacity (CEC) and pHBC of these paddy soils, indicating that soil CEC is a key factor affecting the pHBC of paddy soils.

The effects of HO- and HNO/HSO-modified biochars on the resistance of acid paddy soil to acidification.

Biochar was prepared from rice straw and modified with 15% HO and 1:1 HNO/HSO, respectively. The unmodified biochars and HCl treated biochars for carbonate removal were used as control. The biochars were added to the acid paddy soil collected from Langxi, Anhui Province, China at the rate of 30 g/kg.

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).

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.

The mechanism for inhibiting acidification of variable charge soils by adhered Pseudomonas fluorescens.

Acidification in variable charge soils is on the rise due to increased acid deposition and use of nitrogenous fertilizers. The associated low pH and cation exchange capacity make the soils prone to depleted base cations and increased levels of Al. Consequently, Al toxicity to plants and soil infertility decrease crop yield.

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.

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.

Mechanisms for Increasing the pH Buffering Capacity of an Acidic Ultisol by Crop Residue-Derived Biochars.

The effects and underlying mechanisms of crop residue-derived biochars on the pH buffering capacity (pHbuff) of an acidic Ultisol, with low pHbuff, were investigated through indoor incubation and simulated acidification experiments. The incorporation of biochars significantly increased soil pHbuff with the magnitude of the increase dependent on acid buffering capacity of the biochar incorporated to the soil. Cation release, resulting from the protonation of carboxyl groups on biochar surfaces and the dissolution of carbonates, was the predominant mechanism responsible for the increase in soil pHbuff at pH 4.

Amelioration of an acidic ultisol by straw-derived biochars combined with dicyandiamide under application of urea.

The rapid increase in agricultural pollution demands judicious use of inputs and outputs for sustainable crop production. Crop straws were pyrolyzed under oxygen-limited conditions at 400 °C for 2 h to prepare peanut straw biochar (PB), canola straw biochar (CB), and wheat straw biochar (WB). Then, 300-g soils were incubated each with urea nitrogen (UN) and UN + biochars with or without dicyandiamide (DCD) for 60 days.