Potential impact of active substances in non-thermal discharge plasma process on microbial community structures and enzymatic activities in uncontaminated soil

Effects of Rotary and Deep Tillage on Soil Environment and Melon Root Development

Tillage practices significantly influence crop yield and soil quality. This study investigated the impact of rotary tillage (RT) and deep tillage (DT) on soil properties, microbial diversity, and melon (Cucumis melo L.) root growth and yield. RT involved breaking up the topsoil to a depth of 15 cm using a rotary tiller, while DT employed a rotary tiller followed by a moldboard plow to turn the soil layer over to a depth of 35 cm. The melon variety "Nasimi" was used as the material. Our findings revealed a remarkable response of soil phosphorus to tillage practices. High-throughput sequencing results revealed a significant impact of tillage practices on the soil fungal composition, richness, and diversity but little impact on the bacterial communities. Compared to RT, DT markedly enhanced melon root length, root surface area, root volume, and mean root diameter by 47.42%, 56.70%, 58.83%, and 27.28%, respectively. Additionally, DT treatments significantly increased melon yield (53.46%) compared to RT. The results indicate that DT improves soil nutrient availability, affects soil fungal community characteristics, and optimizes root distribution in soil, thereby improving melon yield. The findings offer valuable theoretical insights for the implementation of effective tillage practices in open-field melon cultivation.

Butachlor (BTR) degradation by dielectric barrier discharge plasma in soil: Affecting factors, degradation route, and toxicity assessment

Over the past few decades, the frequent and excessive usage of pesticides has had detrimental effects on the soil and other habitats. In terms of removing organic contaminants from soil, non-thermal plasma has become one of the most competitive advanced oxidation methods. The study used dielectric barrier discharge (DBD) plasma to repair soil contaminated by butachlor (BTR). BTR degradation was investigated in actual soil under various experimental parameters. According to the results, DBD plasma treatment at 34.8 W destroyed 96.10% of BTR within 50 min, and this degradation was consistent with the model of first order kinetics. Boosting the discharge power, lowering the initial BTR concentration, using appropriate soil moisture content and air flow rate, and using oxygen as the working gas for discharge are all beneficial to the degradation of BTR. The changes in soil dissolved organic matter (DOM) before and after plasma treatment were assessed using a total organic carbon (TOC) analyzer. A Fourier transform infrared (FTIR) spectroscopy and an Ultra Performance Liquid Chromatography Tandem Mass Spectrometry (UPLC-MS) were employed to investigate the degradation of BTR. A wheat growth test showed that the best growth was achieved at 20 min of plasma soil remediation, but too long treatment would lower soil pH and thus affect wheat growth.

Effects of novel bioorganic fertilizer application on soil enzymes and bacterial community in multi-site rice paddies in China

Application of a novel bioorganic fertilizer (BIO) has been effectively used to inhibit weeds in rice paddies. To identify changes in soil bacterial community and enzymes in response to BIO treatments, field experiments were carried out in five major rice-growing areas in China. The dominant phylogenetic groups recorded included Proteobacteria, Actinobacteria, Bacteroidetes, Firmicutes and Acidobacteria. Anaeromyxobacter, Bacteroides, Bifidobacterium, Escherichia- Shigella, Geobacter and Haliangium were significantly different between BIO-treatment and untreated control and aided in general function (R), amino acid transport, metabolism (E) and transcription (K) clusters. The soil chemical properties and enzyme activities were less affected by BIO at these study sites. RDA analysis showed that soil bacterial community had a significant positive correlations among northern latitude, eastern longitude, exchangeable K, total K, total P, soil pH, and total N, except for organic matter, hydrolytic N and extractable P. Overall, our work showed that application of BIO does not alter the main community structure and functional diversity of soil bacteria in rice paddies and should be encouraged for use as a sustainable weed management strategy.

Application of enzymes as a diagnostic tool for soils as affected by municipal solid wastes

Assessing the relationship between soil enzyme activities (SEAs) and heavy metals (HMs) without any amendment has rarely been conducted in soils contaminated with municipal solid wastes (MSW). Five soil enzymes [dehydrogenase (DHA), alkaline phosphatase (ALP), acid phosphatase (ACP), urease (UR), and nitrate reductase (NR)] have been assessed for HMs bioremediation using Zea mays L. grown in unamended soils that were contaminated with different types of MSW. Pot experiment was conducted for two seasons with soils collected from seven different locations within the MSW site. Experimental soil samples included a control (CA), contaminated by brick kiln wastes (SA1), kitchen and household wastes (SA2), medical wastes (SA3), mixed wastes (SA4), glass wastes (SA5), and metal scrap wastes (SA6). Rhizospheric soils were collected after the harvest of each season to investigate the impact of HMs on SEAs and physicochemical properties of soil. The results revealed an increase in DHA, ALP, and NR activities by 89.30%, 58.03% and 21.98% in SA1. Likewise, enhanced activities for UR (28.26%) and ACP (19.6%) were observed in SA3 and SA5 respectively. Insignificant increase in the macronutrients and organic carbon (OC) were also noted. The increased microbial count and the relatively higher amount of organic matter (OM) in the rhizosphere indicated the role of OM in HMs immobilization. Principal component analysis (PCA) indicated that DHA and NR are the important soil enzymes, underscored by their active involvement in the C and N turnover in the soil. Likewise, correlation analysis showed that DHA and NR activities were positively correlated with copper (Cu) (0.90, p < 0.01; 0.88, p < 0.01), suggesting its participation as a cofactor in enzymatic activities. In contrast, DHA was negatively correlated with cadmium (Cd) (-0.48, p < 0 0.05). Finally, these results indicated that in the absence of exogenous nutrient amendment, the SEAs were governed by OC, available nitrogen (Avl. N), Cu and Cd respectively. The study also highlighted the need for extensive research on SEAs for its utilization as a bioindicator in various soil bioremediation and quality management practices.