Potting Soil Research Articles

Calcium acetate enhances both drought tolerance and arsenic accumulation in Pteris vittata

ABSTRACT Pteris vittata, the first discovered arsenic (As) hyperaccumulator, has great potential in As-contaminated soil remediation. However, as a fern, it is sensitive to water deficiency. In this study, acetic acid and calcium acetate were added to As-contaminated soils in pots to investigate their effects on the drought tolerance, growth and As remediation efficiency of P. vittata. Comparing with the plants pretreated with municipal drinking water, plants pretreated with 20 mM acetic acid or calcium acetate solutions exhibited strikingly increased drought tolerance. In addition, 20 mM calcium acetate significantly increased shoot As concentration by 165% and the total shoot As amount by 55.1%, probably due to the elevated soil pH and a subsequent 14.2% increase of soil available As. Taken together, this study demonstrates that the appropriate application of calcium acetate can enhance both drought tolerance and As accumulation in P. vittata, which is of significance for the phytoremediation.

Fruit Peel Soil Supplementation Induces Physiological and Biochemical Tolerance in Schefflera arboricola L. Grown Under Heat Conditions

Schefflera plant is propagated and grown under greenhouse cultivation, and most of these greenhouses are low-cost. In the summer, the heat generated in greenhouses becomes a limiting factor for plant growth and, subsequently, limits the production of high-quality species under greenhouse conditions. The powder of banana (B), orange (O), and pomegranate (P) peels and their combinations were added as soil supplementation at rates of 8 and 16 g/pot to the pots of Schefflera plants, which were grown during the summer season under a low-cost greenhouse. The growth analysis was estimated after 150 and 180 days from planting. Heat conditions significantly inhibited the relative growth rate, crop growth rate, and absolute growth rate (AGR) of Schefflera plants, but fruit peel applications were shown to markedly mitigate its negative impact. Fruit peel applications augmented the shoot and root growth rates and leaf pigments, decreased AGR reduction, promoted relative water content, increased membrane stability index (MSI), and alternated the phenotypic plasticity index (PPI). Fruit peels significantly increased total phenol and flavonoid levels as well as the antioxidant activity (DPPH), which positively alleviated the oxidative damage (decreased H2O2 and MDA contents) that occurred in plant leaves, and induced heat-shock protein synthesis, leading to plants with greater heat tolerance. Orange peel application at the rate of 16 g/pot to the potting soil is more beneficial for root initiation and development during the early phases of Schefflera plant life, as well as more effective in increasing the aerial portions and inducing resistance to heat conditions in low-cost polyethylene greenhouses.

Plant growth-promoting properties of the phosphate-solubilizing red yeast Rhodosporidium paludigenum

Phosphorus (P) is one of the essential elements that are necessary for plant development and growth. However, the availability of soluble forms of P for plants in the soils is limited, because a large proportion of it is bound to soil constituents. Thus, the concentration of P available to plants at any time is very low and, moreover, its availability depends on the soil pH. As a solution, phosphate-solubilizing microorganisms (PSMs) are employed that render inorganic P available to plants in soluble form. Thus far, research into PSMs has been insufficient, and only few such organisms have been considered for exploitation as microbial fertilizer strains. The characteristics of plant growth promotion with the plant-PSMs coculture system remain to be elucidated. In the current study, we report on the isolate Rhodosporidium paludigenum JYC100 that exhibits good performance for solubilizing calcium phosphate. We found that it can be regulated by the amount of soluble phosphate. Furthermore, R. paludigenum JYC100 promotes plant growth under specific conditions (P deficiency, but with insoluble phosphate) in different media and soil pots. In contrast, the yeast Aureobasidium pullulans JYC104 exhibited weak phosphate-solubilizing capacities and no plant growth-promoting ability. Compared to control plants, the biomass, shoot height, and cellular inorganic P content of plants increased in plants cocultivated with R. paludigenum JYC100. In addition, histochemical GUS and qRT-PCR assays of phosphate starvation-induced (PSI) genes showed that the transcript levels of these PSI genes are decreased in the plants cocultured with R. paludigenum JYC100. These findings reflect the unique ability of R. paludigenum JYC100 to convert insoluble P compounds to plant-available P, thereby leading to growth promotion. Our study results highlight the use of yeasts as potential substitutes for inorganic phosphate fertilizers to meet the P demands of plants, which may eventually improve yields in sustainable agricultures.

Growth and Yield of Screenhouse-grown potted Pechay (Brassica rapa L. ssp. chinensis cv. Black Behi) in selected Davao-produced Composts

Pak choi (Brassica rapa subsp. chinensis), locally called pechay, is a nutritious and sought-after vegetable among Asian consumers as its edible petioles and green leaves are suitable in various recipes. The use of composts and organic amendments is integral to organic agriculture which is promoted in Davao City, Philippines. However, there are no published local studies in the city on the effect of recently formulated composts on crops. Thus, this study explored how these compost amendments affect the growth and yield of potted Black Behi pechay under screenhouse conditions using a completely randomized design. Results revealed that germination was higher in seeds sown in pure potting mix (90 to 94 %) and vermicompost-amended potting mixes (94 to 100 %) than with Dr. Bo’s Biofertilizer (DBB) (75 to 92%). Mean plant height (18.42 cm), leaf length (10.31 cm) and leaf width (5.89 cm) were highest in plants grown in potting mixes amended with 20% Tacunan vermicompost (Tacunan). Furthermore, there were pest and disease incidences in plants under all treatments but the least incidence was observed in plants grown in DBB. Total fresh weight (14.71 g), dry weight (0.76 g) and marketable fresh weight (12.19 g) obtained were exhibited by plants grown in 20% Tacunan. Total biomass, however, was highest in the urea-amended potting mix (15.42%). Results revealed that the application of composts positively influenced the growth and development of Black Behi pechay with 20% Tacunan as the recommended amendment.

Feasibility study for estimating optimal substrate parameters for sustainable green roof in Sri Lanka

In twenty-first century buildings, green roof systems are envisioned as great solution for improving Environmental sustainability in urban ecosystems and it helps to mitigate various health hazards for humans due to climatic pollution. This study determines the feasibility of using five domestic organic wastes, including sawdust, wood bark, biochar, coir, and compost, as sustainable substrates for green roofs as compared to classical Sri Lankan base medium (fertiliser + potting mix) in terms of physicochemical and biological parameters associated with growing mediums. Comprehensive methodologies were devised to determine the thermal conductivity and electric conductivity of growing mediums. According to preliminary experimental results, the most suitable composition for green roof substrates comprised 60% organic waste and 40% base medium. Sawdust growing medium exhibited the highest moisture content and minimum density magnitudes. Biochar substrate was the best performing medium with the highest drought resistance and vegetation growth. The wood bark substrate had the highest thermal resistance. Growing mediums based on compost, sawdust, and coir produced the best results in terms of nitrate, phosphate, pH, and electric conductivity (EC) existence. This study provided a standard set of comprehensive comparison methodologies utilising physicochemical and biological properties required for substrate characterization. The findings of this research work have strong potential in the future to be used in selecting the most suitable lightweight growing medium for a green roof based on stakeholder requirements.

Comparative growth analysis of cumin plants (Cuminum cyminum L.) treated with glycerol and talc based phosphate solubilizing bacterial consortia

Cumin (Cuminum cyminum L.) is a versatile annual herb cultivated in the Middle East, India, China, and Tunisia. The seeds of this plant are primarily used in cooking as common food additives and traditional medicines to treat hypolipidemia, cancer and diabetes. However, cumin plants have poor germination and weak establishment rate, particularly under drought stress. The present study aimed to examine the growth promotion potential of cumin plants treated with talc and glycerol-based phosphate solubilizing bacteria (PSB) consortia. Four efficient PSB were isolated from the rhizosphere of Calotropis procera and Solanum lycopersicum and identified through 16S rRNA sequencing as Pseudomonas nitritireducens MF351819, Klebsiella pneumoniae MF351845, Erwinia sp. MF351846 and Pantoea dispersa MF351847. In a nursery experiment on cumin (Cuminum cyminum) plants, 15 treatments of single, dual, triple and quadruple combinations of four PSB isolates were formulated on glycerol and talcum powder-based bacteriological carriers. The 100-day pot experiment was initiated during the winter of 2016 (the last week of October) containing loamy sand soil of Sardarkrushinagar, Gujarat. The formulations were applied to pot soil containing seven-day-old cumin seedlings. With glycerol-based PSB inoculations, the P14 treatment containing a consortium of K. pneumoniae MF351845, Erwinia sp. MF351846, and P. dispersa MF351847 provided the highest per plant seed yield of 0.19 g. With talc-based PSB inoculations, the P11 treatment containing a consortium of K. pneumoniae MF351845, Erwinia sp. MF351846, and P. nitritireducens MF351919 produced the highest per-plant cumin seed yield of 0.42 g. Overall, talc-based PSB consortial treatments improved height, dry weight, 100 seed weight and yield of the cumin plant.

Optimized Production of Second-Generation Bioethanol from a Spent C4 Grass: Vetiver (Chrysopogon zizanioides)

Vetiver grass (Chrysopogon zizanioides) is well-known for its contaminant phytoextraction potential and its capacity to reduce soil erosion, owing to its massive, dense root system. However, the shoots are not major contributors to either of these processes, and are either not utilized at all or they become part of the waste stream. It is well-recognized that lignocellulosic biomass can serve as a source of raw material to produce second-generation bioethanol. This study investigated the simultaneous saccharification and fermentation (SSF) of acid–alkali pretreated vetiver (VG) shoots by Saccharomyces cerevisiae. Vetiver shoots were obtained from three sources: (1) shoots from VG grown in clean potting soil, (2) shoots from VG used for antibiotics phytoextraction from a constructed wetland setup, and (3) shoots from VG used for lead phytoextraction during soil remediation. Bioethanol yield from the shoots from clean soil was the highest (19.58 g/L), followed by the one used for lead phytoextraction (19.50 g/L) and the one used for antibiotics phytoextraction (19.17 g/L). Bioethanol yield and quality obtained from these three VG shoots was superior or similar to other C4 grasses used for bioethanol generation. This study successfully demonstrated that spent vetiver biomass after phytoextraction applications can be repurposed to generate high-quality bioethanol.

Four-dimensional measurement of root system development using time-series three-dimensional volumetric data analysis by backward prediction.

Root system architecture (RSA) is an essential characteristic for efficient water and nutrient absorption in terrestrial plants; its plasticity enables plants to respond to different soil environments. Better understanding of root plasticity is important in developing stress-tolerant crops. Non-invasive techniques that can measure roots in soils nondestructively, such as X-ray computed tomography (CT), are useful to evaluate RSA plasticity. However, although RSA plasticity can be measured by tracking individual root growth, only a few methods are available for tracking individual roots from time-series three-dimensional (3D) images. We developed a semi-automatic workflow that tracks individual root growth by vectorizing RSA from time-series 3D images via two major steps. The first step involves 3D alignment of the time-series RSA images by iterative closest point registration with point clouds generated by high-intensity particles in potted soils. This alignment ensures that the time-series RSA images overlap. The second step consists of backward prediction of vectorization, which is based on the phenomenon that the root length of the RSA vector at the earlier time point is shorter than that at the last time point. In other words, when CT scanning is performed at time point A and again at time point B for the same pot, the CT data and RSA vectors at time points A and B will almost overlap, but not where the roots have grown. We assumed that given a manually created RSA vector at the last time point of the time series, all RSA vectors except those at the last time point could be automatically predicted by referring to the corresponding RSA images. Using 21 time-series CT volumes of a potted plant of upland rice (Oryza sativa), this workflow revealed that the root elongation speed increased with age. Compared with a workflow that does not use backward prediction, the workflow with backward prediction reduced the manual labor time by 95%. We developed a workflow to efficiently generate time-series RSA vectors from time-series X-ray CT volumes. We named this workflow 'RSAtrace4D' and are confident that it can be applied to the time-series analysis of RSA development and plasticity.

Stable Isotope Analysis of Residual Pesticides via High Performance Liquid Chromatography and Elemental Analyzer-Isotope Ratio Mass Spectrometry.

To broaden the range of measurable pesticides for stable isotope analysis (SIA), we tested whether SIA of the anthranilic diamides cyantraniliprole (CYN) and chlorantraniliprole (CHL) can be achieved under elemental analyzer/isotope ratio mass spectrometry with compound purification in high-performance liquid chromatography (HPLC). Using this method, carbon isotope compositions were measured in pesticide residues extracted from plants (lettuce) grown indoors in potting soil that were treated with 500 mg/kg CHL and 250 mg/kg CYN and were followed up for 45 days. Our results show that the CYN and CHL standard materials did not have significant isotope differences before and after clean-up processing in HPLC. Further, when applied to the CYN product and CHL product in soil, stable isotope differences between the soil and plant were observed at <1.0‱ throughout the incubation period. There was a slight increase in the variability of pesticide isotope ratio detected with longer-term incubation (CHL, on average 1.5‱). Overall, we measured the carbon isotope ratio of target pesticides from HPLC fraction as the purification and pre-concentration step for environmental and biological samples. Such negligible isotopic differences in pesticide residues in soils and plants 45 days after application confirmed the potential of CSIA to quantify pesticide behavior in environments.

Exploration of wheatgrass as functional food by using urban agriculture models for regulating growth &amp; nutrients

Limitation to cultivable area and increasing food demand has steered development of urban farming. Practice of container gardening, patio gardening and rooftop gardening cause soil erosion while soil-less systems like hydroponics and aeroponics are expensive. Balancing traditional and contemporary methods need to be identified. We assessed the growth and nutrient values of functional food wheatgrass (Triticum aestivum L.) cultivated in different growth media – soil, hydroponics, aeroponics and paper-pulp based potting mix soil. Height, fresh weight, protein, minerals, and vitamins composition of wheatgrass plantlets were estimated. Construction and running costs for six-month period were compared. Plantlets harvested from potting mix soil had highest height & weight gain (at 88.67 cm and 15.13 gm) and all-around nutrient contents over others. Cost analysis shows that working costs for potting mix soil-based systems are most productive for a long duration (17x and 23x cheaper than hydroponics and aeroponics). The current study shows suitability of potting mix soil over other cultivation methods for wheatgrass for urban farming needs. Potting mix does not contribute to soil erosion as in case of natural soil based urban farming. Our results support the idea of utilization of potting mix for urban agricultural needs without indulging in cost- and technology- invested methods.

Kontrollü koşullar altında Aspergillus niger kültür filtratının kök-ur nematodu Meloidogyne incognita’ya karşı nematisidal etkisinin belirlenmesi

Amaç: Bu çalışmada Aspergillus niger’in kültür filtratının 4 farklı(25, 50, 75 ve 100%) konsantrasyonunun kontrollü koşullar altında (24±1 ° C, 60±5% nem) domates ve biber köklerinde Meloidogyne incognita gelişimine etkisi araştırılmıştır.Yöntem ve Bulgular: Çalışmada nematod inokulumu olarak 500 II. Dönem larva (J2) kullanılmış ve inokülasyonundan iki gün sonra her saksı toprağına A. niger kültür filtratının her konsantrasyonundan 10 ml uygulama yapılmıştır. Uygulamadan 8 hafta sonra köklerdeki gal ve yumurta paketi sayıları ile topraktaki J2 yoğunluğu tespit edilmiş ve konsantrasyonların bu parametrelerdeki kontrol etki yüzdeleri hesaplanmıştır. Domates ve biber köklerinde M. incognita üzerinde en etkili konsantrasyonların %100 ve %75 olduğu saptanmış ve gal, yumurta paketi sayısı ve topraktaki J2 yoğunluğu üzerindeki etkileri arasında önemli bir fark bulunmamıştır (P≥0.05). A. niger kültür filtratının %50 seyreltmenin altına düştüğünde, nematisidal etkisinin %30’lara kadar düştüğü belirlenmiştir. Domateste kültür filtratının %100 konsantrasyonunda gal, yumurta paketi sayısı ve topraktaki J2 yoğunluğu üzerindeki yüzde kontrol etki sırasıyla %86.3, 86.2 ve 82.0 olarak saptanırken, biber köklerinde %89.1, 88.6 ve 87.2 olduğu bulunmuştur. A. niger’in %75 konsantrasyonunda ise gal, yumurta paketi sayısı ve topraktaki J2 yoğunluğu üzerindeki kontrol etki domateste sırasıyla %79.9, 79.2 ve 73.0 olarak belirlenirken, biberde %82.9, %82.0 ve %79.4 olduğu tespit edilmiştir. Genel Yorum: Yerel A. niger izolatının M. incognita’ya karşı yüksek nematisidal aktivite gösterdiği tespit edilmiştir. Çalışmanın Önemi ve Etkisi: A. niger kültür filtratı domates ve biberde M. incognita kontrolünde yeni bir biyolojik nematisit kaynağı olarak belirlenmiştir.

Manure soil amendment for Grevillea robusta seedlings in the Kenyan highlands

Grevillea robusta seedlings are of high demand in Kenyan agricultural landscapes especially in agroforestry systems, yet the ideal soil mixture is not identified. This experiment was to determine the ideal potting soil mixture for Grevillea species. A Complete Randomized Design (CRD) with 4 treatments replicated 3 times was employed. Four treatments were used; Forest soil, Agricultural soil, Forest soil + Manure and Agricultural soil + Manure. The experiment was done for 8 months in 2020 at Egerton University tree nursery. Data was collected on seedling survival, height, root and foliage variables. One-way ANOVA was performed on the measured variables using SAS statistical package while the means were separated using LSD at P&lt; 0.05. Results showed that Agricultural soil + Manure was significantly higher (P&lt;0.05) in all the shoot and foliage variables compared with Agricultural soil alone except for internode length. Besides, Agricultural soil + Manure showed similar growth performance with Forest soil alone. However, the former showed significantly higher leaf length (20.2 cm) compared with Forest soil + Manure (14 cm). Results showed that Forest soil and Agricultural soil + Manure had significantly higher (P&lt;0.05) root biomass compared with Agricultural soil (2.77 g), while root collar diameter, root length and root to shoot ratio were similar. It is, therefore, recommended that tree nurseries located far from forests can use a potting soil mixture of Agricultural soil + manure in raising Grevillea seedlings since this gives similar growth performance with forest soil.

A Comparative Evaluation of Aquaponic and Soil Systems on Yield and Antioxidant Levels in Basil, an Important Food Plant in Lamiaceae

Greenhouse and aquaponic productions of basil (Ocimum basilicum L.) are well established, but the comparison between these two methods is not studied in detail. A study was conducted to evaluate the performance of basil in both aquaponic and soil systems under greenhouse conditions. The plants were raised in aquaponic beds with ornamental fish and a set of plants was raised in soil pots under a greenhouse setup. The studied parameters were morphological, biochemical and antioxidant levels. In order to analyze the stress effects of an aquaponic system on plant defense mechanism, two different antioxidant enzymes (catalase and peroxidase) were analyzed. Water quality parameters were monitored during the entire study period. Based on the results, there was a significant increase in growth parameters in the aquaponic system when compared to the conventional greenhouse cultivation of basil plants. The photosynthetic parameters showed a decline in the aquaponic system, but the biochemical parameters showed an enhancement in the aquaponic system of growing basil plants. The antioxidants exhibited a significant increase in the aquaponic system, which suggests a water stress effect on the plants induced by the aquaponic growing system. From the results of this study, it can be concluded that the aquaponic system is the best suitable method for basil production in the UAE condition.

Using radish (Raphanus lativus L.) germination to establish a benchmark dose for the toxicity of ozonated-petroleum byproducts in soil

The concentration-response relationship between the germination outcome of radish (Raphanus lativus L.) and ozonated petroleum residuals was determined experimentally. The outcomes were used to produce an ecological risk assessment model to predict the extra risk of adverse outcomes based on the concentration of ozonated residuals. A test soil with low organic matter (0.5% w/w) was mixed with raw crude oil, artificially weathered, and treated at three doses of ozone (O3) gas (5 g, 10 g, and 40 g O3 per 600 g of soil). Total petroleum hydrocarbons (TPH) and produced dissolved organic carbon (DOC) were measured. TREATMENT categories (control, petroleum, petroleum + 5 g O3, petroleum + 10 g O3, and petroleum + 40 g O3) were then used to create a dilution series using different proportions of the test soil and a commercially available potting mix (∼75% w/w organic matter) to evaluate the effects of background organic matter (b-ORGANIC) in conjunction with TPH and DOC. Multivariable logistic regression was performed on the adverse germination outcome as a function of TPH, DOC, TREATMENT, and b-ORGANIC. The parameters controlling germination were the continuous variable DOC and the categorical variables TREATMENT and b-ORGANIC. Radish germination was strongly harmed by DOC from ozonation, but DOC's ecotoxicity decreased with increasing O3 dose and the presence of b-ORGANIC beyond 10% (w/w). We used the germination outcome of radish to produce a logistic regression model that computes margins of DOC (± std. error) that create 10%, 25%, and 50% extra risk of adverse germination effects.

Phytotoxicity level and accumulation ability of pot marigold (Calendula officinalis L.) to zinc

The study aims to reveal the effects of different Zn levels on pot marigold. We determined some germination and young seedling properties in the first experiment, and morphological, stomatal, and physiological parameters besides uptake profiles of both Zn and other plant nutrients in the second one. We supplied the water requirement of the seeds with Zn solutions (0, 250, 500, 750, and 1,000 mg l−1) in the first experiment, and We added the same zinc doses as mg kg−1 to the soil of the pots where the plants would grow in the second one. As a result, the inhibitory effects were more prominent in the early seedling stage (especially at 1,000 mg l−1 Zn) than in the germination one. We determined plant growth retardation, decreases in leaf water contents, and increases in membrane damages with higher Zn (≥500 mg kg−1) in the experiment conducted by potting soil. We detected decreases in chlorophyll parameters parallel with the increases in Zn. The alterations in plant zinc contents revealed the accumulation capacity of pot marigold in potting conditions. That TF value >1 in Zn treatments up to 500 mg kg−1 points to the efficiency limit of pot marigold as a Zn-accumulator plant.

Assessing Processing Waste from the Sea Urchin (Centrostephanus rodgersii) Fishery as an Organic Fertilizer

The longspined sea urchin, Centrostephanus rodgersii, is a climate-driven pest species in south-eastern Australia. The harvest of this species is highly encouraged and in Tasmania, the existing fishery is expanding resulting in a large amount of waste that needs disposal. Research into use of waste products as inputs for organic or biodynamic farming systems can help reduce costs of disposal and keep the industry profitable; by sustaining or incrementing sea urchin harvest the industry can assist in their control. In the current study, urchin waste was dried and finely ground to a powder and applied to tomato plants in a greenhouse to examine the effect on growth and productivity. Urchin waste powder (UWP) had a mineral composition of Ca (40 g 100 g−1), Mg (1.7 g 100 g−1), P (0.03 g 100 g−1), Fe (19.34 mg kg−1) and B (38 mg kg−1), a pH 8.06 in water and an Electrical Conductivity (EC) value of 7.64 dSm−1. Seven different treatment rates of UWP (0.3%; 0.5%; 0.8%; 1%; 2%; 3%; 5%), were added to 10 replicate pots containing 4 kg nutrient-poor potting mix planted with tomato (Variety K1) seedlings. Plant growth, yield, quality attributes and mineral content of tomato were measured under UWP treatments with comparison against a Hoagland solution control. UWP influenced tomato growth and productivity proportional to the quantity applied, however, the Hoagland solution control had a significantly greater yield. Potting mix pH increased from 6.8 to 7 and higher available P was detected in potting mix receiving higher rates of UWP. No phytotoxic effects were detected. The highest UWP treatment matched the Hoagland control in fruit quality and nutritional composition. Processing waste from the sea urchin fishery has potential as organic fertiliser or amendment providing plant-available Ca and some microelements such as Boron.

Effects of sterilization methods on the survival of pathogenic bacteria in potting soil stored at various temperatures

Fresh food products can be contaminated with pathogenic bacteria in various agricultural environments. Potting soil is sterilized by heat sterilization and then reused. This study evaluated the effects of three sterilization methods (non-sterilized, pasteurized, and sterilized) on the survival of pathogenic bacteria in potting soil during storage for 60 days at 5, 15, 25, and 35 °C. The reduction in Escherichia coli O157:H7, Salmonella Typhimurium, and Staphylococcus aureus in potting soil was higher at higher temperatures (25 and 35 °C) than at lower temperatures (5 and 15 °C). The population of pathogenic bacteria in pasteurized and sterilized potting soil was reduced below the detectable levels within 30 days at 35 °C. In contrast, the population of Bacillus cereus did not change in potting soil during storage for 60 days at all temperatures. These results indicate that sterilization and storage temperature of potting soil are critical factors influencing the survival of pathogenic bacteria.

Different feedstocks of biochar affected the bioavailability and uptake of heavy metals by wheat (Triticum aestivum L.) plants grown in metal contaminated soil

Heavy metals (HMs) contamination of agricultural soils is an emerging food safety challenge at world level. Therefore, as a possible treatment for the remediation of a HMs contaminated soil (sewage water irrigation for 20-years), the impact of biochar (BC) was investigated on the uptake of HMs by wheat (Triticum aestivum L.) plants. The BC was produced from seven different feedstocks (cotton stalks (CSBC), rice straw (RSBC), poultry manure (PMBC), lawn grass (LGBC), vegetable peels (VPBC), maize straw (MSBC), and rice husks (RHBC)). Each BC was applied at 1.25% (dry weight basis, w/w) in contaminated soil and a control was maintained without BC addition and wheat was grown in potted soil and harvested at maturity. Results revealed that the properties of different biochars regulated their effects on soil nutrient and HMs mobility and uptake by plants. The maximum plant phosphorous and potassium uptake and translocation to grain (173.4% and 341%, respectively) was found in RSBC treatment over control. The RHBC, PMBC, and MSBC treatments showed a maximum decrease in grain Cd concentration (32.9%, 33.8%, and 34.1%, respectively) compared to the control. The grain Pb (−41% to −51%, with no significant differences among different treatments) and Ni (−63%) concentrations were also reduced significantly following BC treatments compared to control. The daily intake and health risk index of Cd were significantly decreased due to PMBC (−28.1% and −33.8%, respectively), and MSBC (−28.3% and −34.1%, respectively) treatment over control. The BC treatments significantly increased the translocation factor of Cd in the order of VPBC (52.1%) > LGBC (25.4%) > CSBC (13.6%) > RSBC (12.1%) compared to control. The study demonstrated that the effects of BC on metal uptake in plants varied with feedstocks and suitable BC can be further exploited for the rehabilitation of contaminated soils and thereby ensuring food safety.

Ultimate fate and possible ecological risks associated with atrazine and its principal metabolites (DIA and DEA) in soil and water environment

Atrazine (AT) is a triazine herbicide widely used to control weeds in several crops. De-isopropylatrazine (DIA) and de-ethylatrazine (DEA) are two of the eight primary metabolites produced by AT breakdown in soil and water. The physico-chemical properties of the soil determine their final fate. So, this study aimed to assess the function of clay loam and sandy loam soils in determining their ultimate fate and the potential ecological risks to non-target species during their persistence in soil and transportation to water bodies. The soil in pots was spiked with standard solutions of AT, DEA, and DIA at 0.3 and 0.6 mg/kg for the persistence study. The leaching potential was determined by placing soils in Plexi columns and spiking them with 50 and 100 µg standard solutions. Liquid-liquid extraction was used to prepare the samples, which were then analyzed using GC-MS/MS. The dynamics of dissipation were first-order. AT, DEA and DIA disappeared rapidly in sandy loam soil, with half-lives ranging from 6.2 to 8.4 days. AT and its metabolites had a significant amount of leaching potential. In sandy loam soil, leaching was more effective, resulting in maximal residue movement up to 30–40 cm soil depth. The presence of a notable collection of residues in leachate fractions suggests the potential for surface and groundwater contamination. In particular, DEA and DIA metabolites caused springtail Folsomia candida and earthworm Eisenia fetida to have longer and greater unacceptable risks. If the residues comparable to the amount acquired in leachate fractions reach water bodies, they could cause toxicity to a variety of freshwater fish, aquatic arthropods, amphibians, and aquatic invertebrates. Future studies should take a more comprehensive approach to evaluate ecological health and dangers to non-target species.

Effects of tobacco plant residue return on rhizosphere soil microbial community

PurposeBased on the recycling principle, returning of tobacco crop residues into the field is a common agronomic practice. However, comprehensive knowledge about the effects of tobacco plant residue return on the rhizosphere soil microbial community is very limited.MethodsAfter tobacco crop residue returning into the potted soil, 16S ribosomal RNA (rRNA) and internal transcribed spacer (ITS) amplicon sequencing were employed to investigate the bacterial and fungal communities, respectively, from the tobacco rhizosphere soils.ResultsThe results showed that tobacco residue returning increased the diversity of microbial communities (bacteria and fungi) and changed the species composition. It further increased the relative abundance of beneficial microorganisms. After tobacco residue returning, the structure of the rhizosphere soil microbial community network was found more complex with strong interactions among microbial species. In addition, the keystone species of bacterial and fungal communities associated with tobacco rhizosphere soil were altered. This had exerted a driving force to the beneficial bacteria such as Sphiningomonas and Psathyrella to the keystone microorganisms which played important roles in microbial species interaction.ConclusionsTobacco residue return into soil showed significant effects on the microbial diversity, community composition, network structure, keystone microorganisms, and ecosystem functions of tobacco rhizosphere soils. This study provides a scientific basis for the improvement of tobacco field ecosystem functioning and ensuring soil health.