Changes in soil microbial community and activity caused by application of dimethachlor and linuron

Soil microorganisms and their activities are essential for maintaining soil health and fertility. Microorganisms can be negatively affected by application of herbicides. Although effects of herbicides on microorganisms are widely studied, there is a lack of information for chloroacetamide herbicide dimethachlor. Thus, dimethachlor and well known linuron were applied to silty-loam luvisol and their effects on microorganisms were evaluated during112 days long laboratory assay. Dimethachlor and linuron were applied in doses 1.0 kg ha−1 and 0.8 kg ha−1 corresponding to 3.33 mg kg−1 and 2.66 mg kg−1 respectively. Also 100-fold doses were used for magnification of impacts. Linuron in 100-fold dose caused minor increase of respiration, temporal increase of soil microbial biomass, decrease of soil dehydrogenase activity, and altered microbial community. Dimethachlor in 100-fold dose significantly increased respiration; microbial biomass and decreased soil enzymatic activities. Microbial composition changed significantly, Proteobacteria abundance, particularly Pseudomonas and Achromobacter genera increased from 7 to 28th day. In-silico prediction of microbial gene expression by PICRUSt2 software revealed increased expression of genes related to xenobiotic degradation pathways. Evaluated characteristics of microbial community and activity were not affected by herbicides in recommended doses and the responsible use of both herbicides will not harm soil microbial community.

Combining mercapto-functionalized palygorskite with zinc affect cadmium phytoavailability and soil microbial activity in rhizosphere soil

Cadmium (Cd) pollution in soil pose a grave threat to human health. Combining various approaches to reduce Cd accumulation in crops is an active area of research to remediate farmlands with medium-high levels of Cd contamination. The Mercapto-functionalized palygorskite (PGS-SH) and zinc (Zn) application alone or in combination was investigated to explore reduction of Cd uptake in B. chinensis L and transformation of Cd in soil. The sole application of Zn or PGS-SH increased the biomass of B. chinensis L. and decreased the concentration of Cd in plants, but more improvements were observed from the combined application of Zn and PGS-SH. Low concentration of exogenous Zn (50 mg/kg) significantly increased the soil respiration rate (SRR) and the soil dehydrogenase activity (sDHA), while promoted B. chinensis L. growth while inhibiting Cd uptake. However, excessive exogenous Zn (≥ 200 mg/kg) significantly inhibited B. chinensis L. growth and soil microbial activity. The combined application of PGS-SH and Zn had the highest sDHA (145.59%) and lowest transport factor (TF) (27.59%) compared with the CK. The combination of PGS-SH and Zn fertilizer is a safe and effective means for remediating Cd-contaminated soil and restoring microbial activity.

Deadwood, Soil and Carabid Beetle-Based Interaction Networks—An Initial Case Study from Montane Coniferous Forests in Poland

In four study plots located in silver fir and Scots pine stands in Magura National Park (southeastern Poland), the relationships between the occurrence and biomass of epigeic carabids, the volume of deadwood and soil biochemical properties were investigated. Thirteen carabid beetle species from the genera Abax, Carabus, Molops and Pterostichus were captured. Rare epigeic carabid species in the fauna of Poland and Europe, such as Carabus glabratus (Paykull), Carabus sylvestris (Panzer) and Abax schueppeli (Germar), were recorded. The number of carabid individuals and species captured as well as the mean individual biomass index at different elevations and in forests of different tree compositions differed significantly. There were no correlations between deadwood volume, carabid abundance and the mean individual biomass of the carabid beetles. The mean individual Carabidae biomass increased with elevated pH, soil carbon content, soil dehydrogenase activity and the number of stumps.

Evaluation of the biological activity of meadow chernozem soils after the application of biochars with different pyrolysis temperatures in a model experiment

The paper aims to study the effect of fresh and aged biochar with different pyrolysis temperatures and metal resistant bacteria on the numbers of microorganisms and the dehydrogenase activity of meadow chernozem soils. The use of fresh biochar leads to an increase in the number of soil bacteria and suppression of dehydrogenase activity; after ageing biochar by incubation in the soil, dehydrogenase activity increases significantly.

Effect of Replanting Zinnia Plants for Remediation of Oil-Contaminated Soil

Previously, we demonstrated that the zinnia plant was effective for the phytoremediation of oil-contaminated soils and that it had a higher remediation effect during the initial growth period. Therefore, repeated planting of zinnia for the initial growth period might enhance the remediation of contaminated soils, so we performed the following study. Seeds were sown in soils containing 4% (w/w) diesel oil and grown for 100 days. We carried out two treatments: replanted plots where above-ground parts of plants were cut after 50 days, and new seeds were sown; or non-replanted plots where plants were allowed to grow for 100 days. The soil dehydrogenase activity and soil total petroleum hydrocarbon concentrations were analyzed. At the end of the study, no significant differences were found between replanted and non-replanted plots for either measurement. Therefore, replanting did not affect remediation. Degradable oil components in the soils may have been degraded in the initial growth period of the first planting, but by the time of replanting there may have been few degradable oil components left in the soil, so there was no beneficial effect of replanting. We concluded that replanting is unsuitable for phytoremediation of oil-contaminated soils.