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The aim of the study was to determine the effects of various petroleum-derived substances (PDSs), namely petrol, diesel fuel, and spent engine oil, on life history traits of the bird cherry-oat aphid Rhopalosiphum padi L., and on the growth and chemical composition of its host plant—winter wheat Triticum aestivum L. Each substance was tested separately, using two concentrations (9 and 18 g kg−1). Plants were cultivated in both control and contaminated soils. In early October 2013, soil was contaminated and after 1 week, winter wheat seeds, ‘Batuta’ cultivar, were sown. In early June 2014, observations of the effect of petroleum-derived substances on traits of three successive generations of aphids were conducted. Aphids were inoculated separately on leaves using cylindrical cages hermetically closed on both sides. Contamination of aphid occurred through its host plant. Results showed that all of the applied petroleum-derived substances have a generally adverse effect on the developmental parameters in aphids, resulting in the decrease of its fecundity, shortening its average life span, and most often lowering of the population intrinsic growth rate. PDSs caused the limitation of growth in wheat plants; whereas, changes in nutrient contents and heavy metals depended on the part of the plant analysed, the substance applied, and on its dose. The negative relationships between the contents of both some macro-elements (Ca, K, P) and heavy metals (Mn, Cd, Cu, and Zn) and the developmental parameters of particular generations of R. padi were observed. The high susceptibility of R. padi to the presence of PDSs in the substrate for the host plant should be emphasised—the clear-cut changes in the life span and fecundity, with relatively small changes in the chemical composition of the plant, constitute an evident indication that the developmental parameters of aphids have the potential for the use as bio-indicator to evaluate the state of the environment contaminated by PDSs.

The aim of the conducted research was to assess the effectiveness of the nitrification process, at different concentrations of ammonium nitrogen, in biologically treated wastewater in one of the largest municipal and industrial wastewater treatment plants in Poland. The studies also attempted to acclimate nitrifying bacteria to the limited concentration of ammonium nitrogen and determined the efficiency of nitrification under the influence of acclimated activated sludge in the biological wastewater treatment system. The obtained results indicate that the concentration of ammonium nitrogen above 60.00 mg·dm−3 inhibits nitrification, even after increasing the biomass of nitrifiers. The increase in the efficiency of the nitrification process in the tested system can be obtained by using the activated sludge inoculated with nitrifiers. For this purpose, nitrifiers should be preacclimated, at least for a period of time, allowing them to colonize the activated sludge. The acclimated activated sludge allows reducing the amount of ammonium nitrogen in treated sewage by approx. 35.0%. The process of stable nitrification in the biological treatment system was observed nine days after introducing the acclimated activated sludge into the aeration chamber.

The purpose of the research conducted was to define the impact of the various aqueous extract concentrations, prepared from the dried (in concentrations 2%, 5% and 10%) and fresh (in concentrations 10%, 20% and 30%) tansy (Tanacetum vulgare L.) mass, on the feeding of pea leaf weevil (Sitona lineatus L.), and the mortality rate of black bean aphid (Aphis fabae Scop.). The studies showed that in order to limit the feeding of pea leaf weevils considerably, it is necessary to use at least 5% extract of the dried tansy mass or 20% extract of the fresh tansy mass. The impeding effect on the feeding of pea leaf weevils was correlated positively with the extract concentration. The insecticide effect of the aqueous extract of tansy on black bean aphid was revealed not earlier than after 12 hours with the use of at least 20% extract of the fresh tansy mass and 5% extract of the dried mass (only in relation to aphid larvae). Nevertheless, the extracts of lower concentration also demonstrated the insecticide effectiveness although delayed (36-60 hours after the application). As compared to other studies conducted according to the same methodology, it was demonstrated that the tansy aqueous extracts are characteristic for a high deterrent activity in relation to the pea leaf weevil beetles (higher than the extracts of absinthe and similar to the extracts of pepper mint and sage) and a quite high aphicidal activity (higher effectiveness than in the case of the aqueous extracts of lemon balm but lower than the extracts of tarragon and absinthe).

Plant protection methods, even those considered as safe for the environment and consumers, may have unexpected effects on nontarget organisms. The effect of broad bean protection, using Pythium oligandrum, paraffin-coated garlic pulp, and extract from grapefruit seeds and pulp on the abundance of epigeic and soil arthropodofauna in a 3-year field experiment was estimated. The effect was compared with chemical protection, which served as the reference to the conventional system. Use of nonchemical products did not affect the overall abundance of the studied arthropods such as Arachnida (except Acarina), Carabidae, Staphylinidae, and Collembola. These methods, however, may favor Formicidae. In comparison to chemicals (carboxin, mancozeb, deltamethrin, and alpha-cypermethrin), nonchemical preparations seemed to be safer for soil mites—they limited their abundance to a lesser degree. Some individual carabid species showed differing responses to the applied protection methods: Amara aenea occurred only in nonchemically protected areas, Platynus assimilis tends to prefer broad beans protected solely with P. oligandrum, while Anchomenus dorsalis prefer plots protected chemically (seed treatment and 3-time spraying). This may be the effect of the different shading of the soil surface as a result of the influence of protection measures on plant growth. Other explanations may include different vulnerability of species to preparations as well as indirect reaction to the occurrence of other taxa (reduced competition and impairment of food sources) or hormesis.

The basic foundation of plant production consists in plant protection treatments, which largely shape the quality of plant raw material intended for the food industry. Due to its long growing season, horseradish requires more treatments than average. Intensive protection based on synthetic pesticides favours the accumulation of their residues in plants and generates serious environmental problems. We have examined the effect of chemical protection and its reduced variant as well as three variants of biological protection, differentiated in terms of preparations used for seedlings treatment (Pythium oligandrum, Bacillus subtilis, and Ecklonia maxima), on the content of dry matter, protein, fat, carbohydrates, and the disease severity index (DSI) of Verticillium wilt of horseradish roots. The quantitative and qualitative changes in the microorganism communities associated with this disease were determined. Thirty-four species of fungi and Globisporangium irregulare have been shown to contribute to the pathogenesis of Verticillium wilt. The following were found with the highest frequency: Verticillium dahliae (14.37%), G. irregulare (6.87%), Ilyonectria destructans (6.73%), Fusarium acuminatum (6.53%), Rhisoctonia solani (6.75%), Epicoccum nigrum (5.56%), and Alternaria brassicae (5.36%).We found that water deficit promotes the increase of DSI and reduces the number and richness of fungal species isolated from diseased roots. The variant of biological protection with treatment of seedlings of E. maxima extract and with reduced chemical protectionin dry seasons give the best protective effects. Under conditions of optimal water supply, biological protection (P. oligandrum) is more effective than chemical protection. Biological protection increases biodiversity in the population of microorganisms that contribute to blackening of the conductive bundles of horseradish roots. There is a significant negative correlation between the number of isolated microorganisms and the DSI value. Increasing the number of the CFUs is accompanied by a reduction in the symptoms of Verticillium wilt of horseradish roots. Biological protection in years with sufficient water supply results in a significant increase in the content of dry matter, protein, and carbohydrates in horseradish roots. Under the influence of protective treatments, the ash content in the roots and its alkalinity decrease.

Due to the growing costs of agricultural production and the need to protect the environment, there has been a need to intensify activities leading to an increase in the effectiveness of natural biological processes. These measures should increase the biodiversity of the environment, enable the adaptation of microorganisms and the protection of plants and soils against the background of the concept of sustainable agricultural development. The soil is an important environment in which many elements are transformed, including nitrogen necessary for the proper yielding of plants. The aim of the article is to present the microbiological aspect of nitrogen transformation, starting with a review of historical findings and then to discuss the progress of the latest developments that have contributed to a detailed understanding of the biochemical reactions occurring during nitrogen transformation in soil. Moreover, the aim of the study is to present the current state of knowledge on the dynamics of nitrogen uptake and conversion by various species of microorganisms and the relationship between the activity of nitrogen microorganisms and nitrogen uptake by plants. The article also includes the latest information on the possibility of using microbiological biostimulants supporting plant growth (PGPR) and protection against the effects of phytopathogens.

Water reuse is now becoming a global necessity. However, one of the drawbacks in releasing wastewater into the environment is some persistent pollutants that are not completely removed in wastewater treatment plant. Residual bacteria and antibiotics in the inflowing wastewater can contribute to the antibiotic resistance spread in the aquatic environment. This study determined the effectiveness of activated sludge process for fecal coliform bacteria elimination, and also the Escherichia coli resistance to antimicrobial agents as erythromycin, azithromycin, clarithromycin, ofloxacin, ciprofloxacin, trimethoprim, and metronidazole in treated wastewater. The research was carried out using the membrane filtration technique, and the susceptibility of isolates to antimicrobial agents was tested by the disc diffusion method. The concentrations of fecal coliform bacteria and Escherichia coli differed significantly depending on the seasonal period in which it was carried out. Despite up to 99% reduction in the number of sanitary indicators in biologically treated wastewater, 89% of E. coli isolates resistant to the tested antibiotics was found, while 100% of the isolates were susceptible to metronidazole. Most of the isolates showed resistance to trimethoprim, and the fewest isolates were resistant to ofloxacin, indicating that some strains may react differently to antibiotics.