Chemical Composition of Soil Contaminated with Tri- and Hexavalent Chromium Amended with Compost, Zeolite and Calcium Oxide

The studies involved determining the influence of Cr(III) and Cr(VI), as well as compost, zeolite and calcium oxide on the content of selected macronutrients and trace elements in soil in which oats were grown. An increase in the content of total chromium, manganese, zinc and nickel took place along with increasing contamination with Cr(III) and Cr(VI). In pots with Cr(VI), the addition of compost significantly increased the contents of copper, zinc and cobalt in the analyzed soil as compared to the control groups. The application of calcium oxide significantly limited the content of copper and cobalt in pots with trivalent chromium, and nickel in pots with Cr(VI); it also contributed to an increase in the contents of chromium and copper (pots with Cr(VI))

Silver nanoparticles (AgNPs) in urea solution in laboratory tests and field experiments with crops and vegetables

Nanotechnology and nanomaterials, including silver nanoparticles (AgNPs), are increas-ingly important in modern science, economics, and agriculture. Their biological activity involvesinfluencing plant health, physiological processes, growth, and yields, although they can also be toxicin the environment. A new fertiliser was made based on a urea solution with a relatively low contentof AgNPs obtained by the reduction of silver nitrate V. Laboratory tests were used to assess theeffect of a fertiliser solution containing 10 ppm AgNPs on the germination of agricultural plant seeds(barley, peas, oilseed rape) and vegetables (radish, cucumber, lettuce) and its foliar application onchlorophyll content, stomatal conductance, and seedling biomass. Field experiments were conductedto assess the effect that a foliar application of 15 ppm AgNPs in working liquid had on physiologicalplant parameters and yields of rape and cucumber. The AgNPs in the tested fertiliser reducedinfestation of the germinating seeds by pathogens and positively affected the physiological processes,productivity, and yields of plants. Plant response depended on plant species and habitat conditions.Reduced pathogen infestation of seeds, higher germination energy, increased chlorophyll content andstomatal conductance, and higher seedling masses all occurred under the influence of AgNPs, mainlyin oilseed rape and cucumber, and especially under thermal stress. The beneficial effect of AgNPson the yield of these plants occurred in years of unfavourable weather conditions. The positiveagricultural test results, especially under stress conditions, indicate that fertiliser produced withAgNPs as an ingredient may reduce the use of pesticides and highly concentrated mineral fertilisers.Such a fertiliser is fully in line with the idea of sustainable agriculture. However, research on theeffects that AgNPs and fertiliser have on the environment and humans should continue

Immobilization of potentially toxic elements (PTE) by mineral-based amendments: Remediation of contaminated soils in post-industrial sites

In many post-industrial sites, the high contents and high mobility of different potentially toxic elements (PTEs) make the soils unsuitable for effective management and use. Therefore, immobilization of PTE seems to be the best remediation option for such areas. In the present study, soil samples were collected in post-industrial areas in Northeastern Poland. The analyzed soil was characterized by especially high contents of Cd (22 mg·kg−1), Pb (13 540 mg·kg−1), and Zn (8433 mg·kg−1). Yellow lupine (Lupinus luteus L.) and two types of mineral-based amendments were used to determine their combined remediation effect on PTE immobilization. A greenhouse pot experiment was conducted to evaluate the influence of chalcedonite and halloysite on plant growth, chlorophyll a fluorescence, the leaf greenness index (SPAD), PTE uptake, and the physicochemical properties and toxicity of soil. The application of chalcedonite resulted in the greatest increase in soil pH, whereas halloysite contributed to the greatest reduction in the contents of Ni, Pb, Zn, and Cr in soil, compared with the control treatment. The addition of halloysite significantly increased plant biomass. The application of mineral-based amendments increased the ratio of variable fluorescence to maximum chlorophyll fluorescence (Fv/Fm) in yellow lupine leaves. The leaf greenness index was highest in plants growing in soil amended with chalcedonite. The results of this study suggest that mineral-based amendments combined with yellow lupine could potentially be used for aided phytostabilization of multi-PTE contaminated soil in a post-industrial area

Research of the biodegradability of degradable/biodegradable plastic material in various types of environments

Research was carried out in order to assess biodegradability of degradable/biodegradable materials made of HDPE and mixed with totally degradable plastic additive (TDPA additive) or made of polyethylene (PE) with the addition of pro-oxidant additive (d2w additive), advertised as 100% degradable or certifi ed as compostable within various types of environments. Research conditions were: (i) controlled composting environment – laboratory-scale, (ii) real composting conditions – domestic compost bin, (iii) real composting conditions – industrial composting plant and (iv) landfill conditions. The results demonstrate that the materials made of HDPE and mixed with totally degradable plastic additive (TDPA additive) or made of polyethylene (PE) with the addition of pro-oxidant additive (d2w additive) or advertised as 100% degradable did not biodegrade in any of the above-described conditions and remained completely intact at the end of the tests. Biodegradation of the certified compostable plastic bags proceeded very well in laboratory-scale conditions and in real composting conditions – industrial composting plant, however, these materials did not biodegrade in real composting conditions – domestic compost bin and landfill conditions

Successful outcome of phytostabilization in Cr(VI) contaminated soils amended with alkalizing additives

This study analysed the effect of three alkalizing soil amendments (limestone, dolomite chalcedonite) on aided phytostabilization with Festuca rubra L. depending on the hexavalent chromium (Cr(VI)) level in contaminated soil. Four different levels of Cr(VI) were added to the soil (0, 50, 100 and 150 mg/kg). The Cr contents in the plant roots and above-ground parts and the soil (total and extracted Cr by 0.01 M CaCl2) were determined with flame atomic absorption spectrometry. The phytotoxicity of the soil was also determined. Soil amended with chalcedonite significantly increased F. rubra biomass. Chalcedonite and limestone favored a considerable accumulation of Cr in the roots. The application of dolomite and limestone to soil contaminated with Cr(VI) contributed to a significant increase in pH values and was found to be the most effective in reducing total Cr and CaCl2-extracted Cr contents from the soil. F. rubra in combination with a chalcedonite amendment appears to be a promising solution for phytostabilization of Cr(VI)-contaminated areas. The use of this model can contribute to reducing human exposure to Cr(VI) and its associated health risks. © 2020 by the authors.Ministerstwo Nauki i Szkolnictwa Wyższego: MNiS

Tillage versus no-tillage. soil properties and hydrology in an organic persimmon farm in eastern Iberian Peninsula

There is an urgent need to implement environmentally friendly agriculture management practices to achieve the Sustainable Goals for Development (SDGs) of the United Nations by 2030. Mediterranean agriculture is characterized by intense and millennia-old tillage management and as a consequence degraded soil. No-Tillage has been widely examined as a solution for soil degradation but No-Tillage relies more on the application of herbicides that reduce plant cover, which in turn enhances soil erosion. However, No-Tillage with weed cover should be researched to promote organic farming and sustainable agriculture. Therefore, we compare Tillage against No-Tillage using weed cover as an alternative strategy to reduce soil losses in persimmon plantations, both of them under organic farming management. To achieve these goals, two plots were established at "La Canyadeta" experimental station on 25-years old Persimmon plantations, which are managed with Tillage and No-Tillage for 3 years. A survey of the soil cover, soil properties, runoff generation and initial soil losses using rainfall simulation experiments at 55 mm h-1 in 0.25 m2 plot was carried out. Soils under Tillage are bare (96.7%) in comparison to the No-Tillage (16.17% bare soil), with similar organic matter (1.71 vs. 1.88%) and with lower bulk densities (1.23 vs. 1.37 g cm3). Tillage induces faster ponding (60 vs. 92 s), runoff (90 vs. 320 s) and runoff outlet (200 vs. 70 s). The runoff discharge was 5.57 times higher in the Tillage plots, 8.64 for sediment concentration and 48.4 for soil losses. We conclude that No-tillage shifted the fate of the tilled field after 3 years with the use of weeds as a soil cover conservation strategy. This immediate effect of No-Tillage under organic farming conditions is very promising to achieve the SDGs

Effect of mounting geometry on convection occurring under a photovoltaic panel and the corresponding efficiency using CFD

Computational fluid dynamics (CFD) is used to model experimental data corresponding to convection occurring under a photovoltaic (PV) panel. Further experimental data is used to validate the model where the satisfactory agreement is received. A standardised condition is set up to allow the effect of varying three geometric parameters to be examined. These are the air gap height (10–500 mm), air gap orientation angle (0–90° from the horizontal) and fluid velocity magnitude (0–3 m/s). The optimum mounting conditions for the PV panel is obtained and maximised electrical efficiency found to favour angles greater than 50° and air gap heights that give an aspect ratio of 60. Mixed convection opposed to natural convection is found to be more effective, with greater efficiencies obtained for larger fluid velocities

Biochar and Sulphur Enriched Digestate: Utilization of Agriculture Associated Waste Products for Improved Soil Carbon and Nitrogen Content, Microbial Activity, and Plant Growth

A number of agriculture residues may be used either directly or after suitable treatment as amendments to improve soil quality. Such materials include biochar made of agriculture residues, digestate or elemental sulphur obtained from biogas desulphurisation. The joint use of these materials via pre-incubation may be more advantageous than only mixing prior the application to soil. In this study, digestates were mixed with amendments and incubated for 6 weeks before application to soil in a short-term pot experiment with lettuce (Lactuca sativa). The following treatments were tested: control digestate, digestate + biochar, digestate + elemental sulphur, digestate + biochar + elemental sulphur. The biochar-enriched digestate significantly increased soil microbial biomass, soil C:N, fresh above ground biomass, fresh and dry root biomass. Elemental sulphur-enriched digestate caused highest arylsulfatase and phosphatase, increased urease, microbial biomass in soil and fresh root biomass. Amendment of digestate + biochar + sulphur led to the significantly highest total soil carbon, microbial biomass, fi-glucosidase, urease, and increased C:N ratio, arylsulfatase in soil and root biomass. It mitigated the adverse effect of either biochar or elemental sulphur on soil respiration. Properties of digestates were apparently affected by pre-incubation. This approach in digestate fertilizer production may contribute to sustainable farming