1,210 publications from this institution
Summary Organic acids have been implicated in many soil‐forming and rhizosphere processes, but their fate in soil is poorly understood. We examined the sorption of four simple short‐chain organic acids (citric, oxalic, malic and acetic) in five acid soils and on synthetic iron hydroxide (ferrihydrite). The results for both soils and ferrihydrite indicated that the sorption depended on concentration in the following order of strength: phosphate >> oxalate > citrate > malate >> acetate. The sorption reactions in soil were shown to be little influenced by pH, whereas for ferrihydrite, sorption of all ligands increased strongly with decreasing pH. The sorption of organic anions onto ferrihydrite was influenced to a lesser extent by the presence of metal cations in solution. From the results we calculated that when organic acids enter solution they rapidly become sorbed onto the soil's exchange complex (> 80% within 10 min), and we believe that this sorption will greatly diminish their effectiveness to mobilize nutrients from the rhizosphere.
The application of biochar to land has been promoted as a strategy for sequestering carbon in soils, for improving soil fertility and remediating soil pollution. However, the implications of biochar amendments on mycorrhizal associations and pesticide decomposition in agricultural soils are poorly understood. In this study, we compared the effects of four treatments; control (no biochar and no arbuscular mycorrhizal fungi (AMF), biochar (biochar without AMF), AMF (AMF without biochar) and biochar + AMF (AMF and biochar) on the fate of simazine. We specifically focused on the sorption, leaching and biodegradation behaviour of simazine. Our results showed that when symbiosis existed between plants and AMF, biochar inhibited simazine decomposition and AMF inoculation alleviated this inhibition. In contrast, this alleviation was not observed when the plant was removed. In addition, AMF inoculated into the biochar amended soil significantly decreased simazine concentration in the leachate; however, in the AMF‐only treatment, no effect on simazine leaching was observed. These phenomena were attributed to variation in the soil's sorption capacity due to biochar application or AMF inoculation. Overall, biochar application combined with AMF inoculation has the potential to mitigate simazine accumulation in the topsoil and reduce its availability.
Slurry acidification has been shown to be effective in reducing environmentally damaging gases. However, this involved the use of concentrated acids on farms. Therefore, due to the health and safety concerns, there is an interest in self-acidification of slurry technique. This study was designed to determine the microbial dynamics leading to self-acidification of slurry. A fresh cattle slurry was amended 10% brewing sugar and stored over 30 days. This fermentable carbon source promoted self-acidification of the slurry from pH 7.0 to 4.7 within four days, and was associated with the accumulation of lactic acid and a reduction in methane and relative ammonia emissions. A metagenomics approach through next generation sequencing (NGS) using an Illumina MiSeq platform was used to determine the microbial diversity and dynamics (bacteria and archaea) in the stored amended slurry. 16S ribosomal ribonucleic acid (rRNA) sequence data revealed the presence of the Order of <i>Lactobacillales</i> was associated with the lactic acid production. The operational taxonomic units (OTUs) abundance indicates that the methanogenic community was dominated by hydrogenotrophic methanogens from the member Order of <i>Methanobacteriales</i>, <i>Methanomicrobiales</i>, and <i>Methanosarcinales</i>. The decrease in tolerance by the methanogens in the self-acidified slurry was probably the main reason for the reduced methane emission. These results confirm, at the microbial level, the mechanism of inhibiting methane production via self-acidification during storage period.
