Search Results (8)

Pig slurry fertigation can modify soil biochemical properties by promoting glomalin production and shifting microbial communities; however, its impacts under varying water regimes remain insufficiently quantified. We assessed irrigated and rainfed systems by integrating the soil quality index (SQI) with total and easily extractable glomalin (T-GRSP, EE-GRSP), determining microbial diversity via eDNA amplicon sequencing, and evaluating enzyme activities across three soil depths (0–10, 10–20, and 20–30 cm). Robust regression revealed that T-GRSP and EE-GRSP accounted for 75% of the SQI variability in irrigated soils and 46% in rainfed soils (p < 0.001), with the strongest correlations in the 0–10 cm layer. Irrigation increased T-GRSP concentrations by 66% (1.78 vs. 1.07 mg g⁻¹) and raised its contribution to total soil carbon from 2.0% to 3.2%. The EE-GRSP levels were slightly lower in the irrigated soils (0.73 vs. 0.76 mg g⁻¹) yet remained a sensitive early-warning indicator of moisture stress in rainfed plots. Microbial profiling showed a 19% increase in Shannon bacterial diversity (3.44 vs. 2.89), even more bacterial communities under irrigation, intermediate fungal diversity, higher fungal abundance, and no detectable arbuscular mycorrhizal fungi in either system. Combining GRSP fractions with microbial and enzymatic markers provides a responsive framework for assessing soil health and guiding organic amendment strategies in fertigation-based agriculture under fluctuating water availability. Full article

Forest fires can have a significant impact on soils, resulting in changes in biological indicators. Due to fire, high temperatures, and intensive generation of smoke from burning materials of different origin, the activity of soil enzymes is decreased. In this study are presented the results of modelling experiments on the impact of smoke on forest soils (Cambisols according to the World Reference Base for Soil Resources rating) of the Republic of Adygea, Nickel settlement (Russia). The findings demonstrated significant smoke exposure on the enzymatic activity of this type of soil. A decrease in the activity of such enzymes as catalase, peroxidase, polyphenol oxidase, and invertase within 60 min after soil treatment with smoke from burning materials of plant origin (pine sawdust) was established. A significant decrease in the activity of catalase relative to the control by 36%, phenoloxidases by 54–58%, and invertase from the hydrolase class by 31% was found. The integral index of soil enzymatic activity (IIEA) of the studied soils was also calculated. In addition, one of the informative diagnostic indicators is the pH of the soil suspension. The pH value for fumigated water was also determined to identify differences with the suspension. A reduction in the pH towards acidification was observed. The obtained findings may be used in a comprehensive assessment of pyrogenic effects on forest soils. Moreover, indicators are sensitive to this effect, which was confirmed by the results of the present research. Full article

Agricultural land is often located close to highly urbanised/industrialised areas and is subject to continuous anthropogenic pressure associated with the emission of many pollutants, ultimately deposited in the soil. Most studies on ecological risk assessment have only analysed the total contaminants’ concentration, which does not reflect their bioavailability or toxicity and often leads to an overestimation of risk. Therefore, in our study, we used an interdisciplinary approach, whereby the final conclusions about the risk in a given area are based on the integration of detailed data from chemical, ecotoxicological and ecological analysis. The research was carried out on agricultural land exposed to high levels of anthropopression for more than 100 years. Chemical measurements comprised both the total and bioavailable PAH content. A battery of bio-assays describing effects on soil retention and habitat function was used for ecotoxicity testing, and ecological indicators included enzymatic activity, respiration, microbial biomass, carbon mineralisation and nitrification. The integrated IntRisk index ranged from 0.19 to 0.94, and this was mainly due to high values of the chemical risk index, while the ecotoxicological and ecological results indicated no or low risk. The majority of the area (almost 90%) had acceptable risk levels, no/low risk (IntRisk < 0.5) at 57% of the sites and medium risk at 28% of the area. Very high unacceptable risk (IntRisk 0.77–0.94) was only at three sampling sites. The integration of data from a set of 15 indicators allowed us to derive quantitative risk indexes and delineate the limited area which needs additional action. Full article

Sustainable agriculture is only possible if the agroecological services of the soil are preserved. Soil contamination with rare elements such as silver (Ag), bismuth (Bi), tellurium (Te), and thallium (Tl) is less studied, but their toxicity is no less high than in other heavy metals. Activity of soil enzymes is of great importance for the healthy functioning of soils, agroecosystem services, and their fertility. It is necessary to assess the ecological state of black soil using the most sensitive and informative indicators of the state of soils—their enzymatic activity. The objective of this research was to evaluate changes in activity of five priority soil enzymes (catalase, dehydrogenases, invertase, phosphatase, and urease) when contaminated with oxides and nitrates of Ag, Bi, Te, and Tl in a laboratory model experiment. The integral toxicity of nitrates and oxides of Ag, Bi, Te, and Tl was assessed by the integrated index of soil enzymatic activity. A comparison of the toxicity of oxides and nitrates of each element, according to the integrated index of soil enzymatic activity, allowed us to establish that Ag oxide is more toxic than Ag nitrate; Bi oxide is equivalent in its toxicity to Bi nitrate; and Tl and Te oxides are less toxic than Tl and Te nitrates. When contaminated with oxides, the most informative indicators are activity of invertase (Ag), urease (Bi, Tl), and phosphatase (Te). When contaminated with nitrates, the most informative indicators are activity of phosphatase (Ag) and invertase (Bi, Tl, and Te). Activity of phosphatase and catalase are the most sensitive to contamination by oxides and nitrates of Ag, Bi, Tl, and Te, and dehydrogenases, invertase, and urease are the least sensitive. Full article

The taxonomic and functional diversity of bacteria in seven different experimental variants applied to soil under a maize plantation was determined by means of next-generation sequencing and biochemical methods. The aim of the study was to discover differences in the structure of bacteria and the level of soil enzymatic activity (BIF—biochemical index of fertility) after the application of a biofertiliser made of lignocellulosic substrate and biochar containing various microorganisms (algae, mycorrhizal fungi of the Glomus genus or the consortium of Bacillus sp. bacteria). The chemical composition and yield of crops was a measurable indicator of the effectiveness of the fertilisers. The biofertilisers influenced both the structure and the percentage share of individual bacterial operational taxonomic units (OTU). The cultivation of maize also modified qualitative and quantitative changes in the soil bacterial microbiome. A canonical variate analysis (CVA) showed that the soil pH exhibited a minimal positive correlation with the soil enzymatic activity and selected plant parameters, with the exception of the biofertiliser variant with arbuscular mycorrhiza (AM). Moreover, the AM biofertiliser significantly increased the BIF value, the yield of maize seeds and the starch content in the plants. The comprehensive nature of the research allowed for a deepening and systematization of the existing knowledge on the influence of biochar with the addition of selected microorganisms on the biochemical parameters of the soil and the bacterial biodiversity of the soil environment. Additionally, the inclusion of the chemical, sanitary composition and yield of maize in the research brought a measurable view of the changes taking place in the soil and plant environment under the influence of the discussed factor. Apart from the agronomic aspect (integrated crop cultivation—Directive 2009/128/EC) of our study, it was also closely related to environmental protection, as it proved that biochar-based biofertilisers could be an alternative to mineral fertilisation. Full article

Selenium (Se) and silicon (Si) are considered advantageous elements to induce plants’ tolerance to various environmental stresses. Wheat yield is negatively affected by salinity stress, especially in dry and semi-dry areas. Therefore, the objective of the current study was to investigate the effects of Se, Si and their combinations (0 as control, Se₁₅, Se₃₀, Si₁₅, Si₃₀, Se₁₅ + Si₁₅, and Se₃₀ + Si₃₀ mM) in alleviating the deleterious effects of salinity stress (7.61 dS m⁻¹, real field conditions) on anatomical characteristics as well as the physio-biochemical and productivity parameters of wheat plants. The selenium and silicon treatments and their combinations caused significant amelioration in growth, anatomical and physiological attributes, and grain yields of salinity-stressed wheat in comparison with the untreated plants (control treatment). The integrated application of Se₃₀ + Si₃₀ significantly increased plant growth (i.e., plant height 28.24%, number of tillers m⁻² 76.81%, fresh weight plant⁻¹ 80.66%, and dry weight plant⁻¹ 79.65%), Fv/Fm (44.78%), performance index (PI; 60.45%), membrane stability index (MSI; 36.39%), relative water content (RWC; 29.39%), total soluble sugars (TSS; 53.38%), proline (33.74%), enzymatic antioxidants (i.e., CAT activity by 14.45%, GR activity by 67.5%, SOD activity by 35.37% and APX activity by 39.25%) and non-enzymatic antioxidants (i.e., GSH content by 117.5%, AsA content by 52.32%), yield and its components (i.e., number of spikelets spike⁻¹ 29.55%, 1000-grain weight 48.73% and grain yield ha⁻¹ 26.44%). The anatomical traits of stem and leaves were improved in wheat plants treated with Se₃₀ + Si₃₀. These changes resulting from the exogenous applications of Se, Si or their combinations, in turn, make these elements prospective in helping wheat plants to acclimate successfully to saline soil. Full article

In recent years, silver nanoparticles (AgNPs) are increasingly used in various industries due to their antibacterial properties, which lead to an increase in pollution of the environment and soil ecosystems. However, the ecological effects of soil pollution by AgNPs were poorly studied than that with AgNPs of other metal-based NPs. The aim of this study is to assess the influence of AgNPs on the biological properties of Haplic Chernozem. Silver was introduced into the soil in the form of AgNPs with a concentration of 0.5; 1; 5; 10; 50, and 100 mg/kg in laboratory conditions. The influence of AgNPs on the biological properties of Haplic Chernozem was assessed 30 days after contamination. The degree of reduction in biological properties depends on the AgNPs concentration in the soil. This study showed that the sensitivity to contamination by AgNPs in the total number of bacteria and enzymatic activity was more than that in the abundance of bacteria of the genus Azotobacter. The integrated index of biological state (IIBS) of Haplic Chernozem was decreased by contamination with AgNPs. Silver nanoparticles in the concentration of 10 mg/kg caused a decrease in the indicator by 13% relative to the control. It also decreased IIBS by doses of 50 and 100 mg/kg by 22 and 27% relative to the control. All used biological indicators could be used for biomonitoring, biodiagnosis, bioindication, and regulation of ecological condition of soil contamination by AgNPs. Full article

Loss of soil biodiversity and fertility in Sub-Saharan Africa (SSA) may put the food security of smallholder farmers in peril. Food systems in SSA are seeing the rise of African indigenous vegetables (AIVs) that are underexploited but locally consumed without being considered a primary source of food and income. Here we present a field study, a first of its kind, in which we investigated the effects of different cropping systems and inclusion of AIVs in the farming approach on bacterial and fungal biodiversity and community structures, enzymatic activity, and the alteration status of soils of the smallholder farmers in Kenya. When compared to mainstream farming approaches, the composition and biodiversity of bacteria and fungi under AIV cultivations was significantly different. Tillage had a significant impact only on the fungal communities. Fertilization and soil amendments caused shifts in microbial communities towards specialized degraders and revealed the introduction of specific microorganisms from amendments. Traditional homemade plant protection products did not cause any disturbance to either of soil bacteria or fungi. The soil alteration index based on enzyme activity successfully differentiated the alteration status for the first time in SSA. These findings could be useful for farmers to integrate AIVs with correct sustainable practices for a sustainable future. Full article