Soil microorganisms, especially rhizobacteria, play a key role in soil phosphorus (P) dynamics and the subsequent availability of phosphate to plants. Utilization of phosphate-solubilizing bacteria as biofertilizers instead of synthetic chemicals is known to improve plant growth through the supply of plant nutrients, and may help to sustain environmental health and soil productivity. The main purpose of this study was to identify new phosphate-solubilizing bacteria isolated from runner bean rhizosphere. Ten out of 25 isolated bacterial strains solubilized Ca3(PO4)2 in qualitative and quantitative P-solubilization. The strain that exhibited the highest potential to solubilize Ca3(PO4)2, was selected for further determination of the mechanisms involved in the process. The medium pH was measured, organic acids released in the culture medium were identified by HPLC analysis, and the acid and alkaline phosphatase activities were determined. Our results showed that strain R7 solubilized phosphorous through the production of various organic acids such as lactic, isocitric, tartaric and pyruvic acids, and that it can be used as a potential biofertilizer.

Contemporary farming practices and rapid industrialization over the last few decades, have raised significant soil and water pollution with extreme toxic effects to humans and ecosystems. The widespread and inefficient use of pesticides, which surpass the soil’s self purification capability, has accelerated soil pollution. In this study, wheat straw biochar was obtained using the traditional pyrolysis technique and its characterization; in addition, the adsorption efficiency of metribuzin was investigated. Biochars’ physical and chemical characteristics were qualified using scanning electron microscopy and Fourier transform infrared spectroscopy. A batch sorption test and liquid chromatography coupled with mass spectrometry were also used to assess the biochar efficiency. SEM and FTIR confirmed the highly reactive surfaces of biochar, establishing efficient biomass conversion in low-oxygen conditions. The adsorption process showed best fit with pseudo second-order kinetic and Langmuir models, suggesting a chemisorption procedure and monolayer-type removal. Regarding its environmental and agricultural application, wheat straw biochar can be advanced as a recommendation solution for further research, which is fundamental for soil rehabilitation and the immobilization of contaminations.

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Herbicide residue analysis has gained importance worldwide, mainly for food quality control to minimize potentially adverse impacts on human health. A Gas chromatography-tandem mass spectrometry (GC-MS) method for quantitative analysis of acetochlor and s-metolachlor in maize and soybean straw has been developed, validated and applied to analyze the residues of anilide herbicides. Straw material was dried, homogenized and extracted with a mixture of n-hexane and acetone by an accelerated solvent extraction method. Chromatographic separation of the target analytes was performed on an Agilent 7832 GC equipped with a mass spectrometer detector, a split-splitless injector and an HP-5 MS (5% phenylmethyl siloxane) capillary column (30 m × 0.25 mm × 0.25 µm). Under these parameters, the limit of detection (LOD) values were 0.2 ng g−1 for acetochlor and 0.07 ng g−1 for s-metolachlor, with average recoveries between 86% and 119.7%. The method was validated for acetochlor and s-metolachlor in maize and soybean straw at 0.5 and 0.01 mg kg −1. Furthermore, the final residues of the two herbicides in maize and soybean straw were below the maximum residue limit (MRL) at harvest time. The proposed method is suitable for routine analysis.

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