Properties Of Agricultural Soils Research Articles

Effect of microplastics used in agronomic practices on agricultural soil properties and plant functions: Potential contribution to the circular economy of rural areas.

The extensive use of plastic materials and their improper disposal results in high amounts of plastic waste in the environment. Aging of plastics leads to their breakdown into smaller particles, such as microplastics (MPs) and nanoplastics. This research investigates plastics used in agricultural practices as they contribute to MP pollution in agricultural soils. The distribution and characteristics of MPs in agricultural soils were evaluated. In addition, the effect of MPs on soil properties, the relationship between MPs and metals in soil, the effect of MPs on the fate of pesticides in agricultural soils and the influence of MPs on plant growth were analysed, discussing legume, cereal and vegetable crops. Finally, a brief description of the main methods of chemical analysis and identification of MPs is presented. This study will contribute to a better understanding of MPs in agricultural soils and their effect on the soil-plant system. The changes induced by MPs in soil parameters can lead to potential benefits as it is possible to increase the availability of micronutrients and reduce plant uptake of toxic elements. Furthermore, although plastic pollution remains an emerging threat to soil ecosystems, their presence may result in benefits to agricultural soils, highlighting the principles of the circular economy.

Crude oil pollution effect on agricultural soil properties and germination of bean (<i>Vigna unguiculata(/i) L.) seed

Crude oil pollution affects not only soil properties but also seed germination. The aim of thisresearch is to checkmate the effect crude oil pollution has on soil fertility, seed germinationand microbial activity. Two different agricultural soils from Ibeno and Otuocha collected bycomposite sampling were used to conduct the study. The crude oil for carrying out the research was sterilized with a micron Chromafil CA/S % 45 syringe filters. The physicochemical analysis of the soil and its microbiological enumeration was done. This was followed by the artificial pollution of the soil with fresh crude oil. Soil’s physicochemical properties and microbiological enumeration were analyzed followed by the planting of bean seed son the polluted soil. Unpolluted soils was also planted and served as the control. The artificial pollution of the soils’ increased physicochemical properties like cation exchange capacity, selenium, mercury, arsenic, carbon and phosphorus in both soil. Some physicochemical properties like electrical conductivity, salinity, vanadium, zinc, cadmium, iron, manganese, copper, cobalt, nickel and nitrogen decreased in both soils. Water permeability was positive and became negative after pollution. Soil texture was bound and became loose after pollution. Other soil properties like pH increased in Ibeno soil but decreased in Otuocha soil. The number of microorganisms decreases after pollution. Statistically, cultivated beans germinated faster on unpolluted soil and appear healthier than polluted soil because of slow germination and a wrinkled appearance. This study shows that crude oil pollution has a significant effect on soil fertility, seed germination and microbial activity.

Use of solid mining waste to improve water retention capacity of loamy soils

Purpose. The research explores the possibility of increasing the fertile properties of agricultural soils of loamy type by adding burnt-out dump mass from coal enterprises. Methods. Laboratory research on parameters of penetration and retention capacity of sorbed and meniscal water for diffe-rent burnt-out rock fractions. The burnt-out rock was sampled from the mine No. 5/6 waste rock dump in the city of Myrnohrad, Donetsk Oblast, and divided into four fractions from 0.63 to 10 mm. The water penetration coefficient of the soil with the added dump mass is measured by the velocity of water seepage into the test samples. The ability of rock additives to retain film-sorbed and capillary water is assessed by comparing the weight of dry and moistened samples of crushed dump mass. Findings. The velocity parameters of water penetration into samples of loamy mixtures with burnt-out dump mass with fractions ranging from 10 to 0.63 mm in size have been determined. It has been found that an increase in the percentage of burnt-out rock in the mixture leads to an increase in the water penetration velocity from 1.2 ml/cm2·min with a rock content of 30% to 30.66 ml/cm2·min with a rock content of 70%. The highest penetration coefficients are achieved when adding rock with a small fractional composition of 0.63-3 mm, since an increase in grain size leads to a reduction in the coefficient by se-veral times. It has been determined that with an increase in the size of the rock fractions in a loamy mixture, the retention capacity of sorbed and pore water suitable for plant nutrition decreases by approximately 40%. Originality. For the first time, the parameters of penetration coefficients, as well as the accumulation of sorbed and meniscal water for mine waste in the Selidovo-Pokrovskyi district of Donbas, have been determined. Practical implications. The results obtained can be used to improve the physical properties of agricultural soils of loamy type by increasing their water retention capacity.

Biochar modifies soil physical properties mostly through changes in soil structure rather than through its internal porosity

AbstractBesides its carbon sequestration potential, biochar application generally improves soil physical properties, but the magnitude of its impact and the underlying mechanisms remain debated and depend on soil type, biochar application rate, and age. The objective was therefore to determine the effect of biochar application rate and age on physical properties of agricultural soils in a temperate climate. On a silt loam and a sandy loam soils, we compared the physical properties of fresh biochar (1% and 2% w/w) or century‐old biochar (0.5%–1% w/w; 19th‐century kiln sites)‐enriched soil samples with biochar‐free soil samples. Biochar pore network characteristics were determined using helium pycnometry, mercury intrusion porosimetry, scanning electron microscopy observation, and electron dispersive X‐ray spectrometry, whereas location of biochar particles within soil structure was analyzed using optical microscopy observations. Fresh biochar application decreased bulk density by 16.8% and increased saturated water content by 16.0% and macroporosity by 78.8%. These effects were attributed to soil structure improvement rather than to biochar porosity. Soil type and biochar application rate had a limited impact. In the long‐term, biochar effects were mostly nonsignificant, which might result from its fairly low content in kiln sites and from the clogging of its internal porosity by clay particles. Biochar was thus able to improve some soil physical properties in the short‐term, but these effects could no longer be detected in the very long‐term. Further investigating the time rate of change in soil physical properties over several decades following biochar additions to soil would therefore seem particularly relevant.

Technologies for Environmental Ecological Restoration and Agricultural Sustainability Are the Focus of Future Safeguarded Agriculture Development

Global agricultural production is facing unprecedented challenges as the environment becomes increasingly polluted. Governments, scientists, companies and farmers are beginning to focus on appropriate environmental remediation and sustainable agricultural technologies and practices. Innovative environmental adaptation/remediation technologies have been developed and validated, including physical/chemical remediation, green sorbents and bioremediation. The development of environmental remediation technologies has provided additional tools and methods for global agri-environment and food security. The aim of this Special Issue is to bring together 21 cutting-edge research papers covering the latest developments in soil conditions, inorganic pollution, organic pollution, remediation technologies and monitoring methods. The four themes of the Special Issue are “Improvement of agricultural soil properties”, “Remediation of potentially toxic element pollution”, “Remediation of organic pollution” and “Ecosystem and crop assessment”. Based on the results of this Special Issue, we find that combining the latest environmental pollution problems with advanced remediation technologies, continuously promoting technological innovation and policy support, and developing integrated new technologies for environmental protection will be future areas of research for sustainable agro-environmental development.

Degradation of Soil Quality Related Physical and Chemical Properties Affected by Agricultural Practice in Le Thuy District, Quang Binh Province, Vietnam

Background: Agricultural practice is considered as main factor affecting land degradation in several regions in Vietnam. However, there are limited studies relating to degraded soil properties and their soil fertility. This paper aimed to evaluate the degradation of agricultural soil under different land management practices. Methods: A total of 80 samples at 0-10 cm of agricultural soil were collected to analyze selected physicochemical properties. The group of degradation soil properties was classified based on their soil fertility using principal component analysis. Result: The results showed that physicochemical properties in agricultural soil along coastal regions were relatively lower than in hilly regions/secondary forests. High ratio of C:N in agricultural soil was because of degradation. The organic matter, nitrogen and phosphorous contents were low in the soil in lowland areas indicating a high level of degradation (1.43%, 0.09% and 0,04%, respectively). The samples classified into four groups (G1, G2, G3, G4) using principal component analysis indicated differences in soil properties due to degradation. Insufficient and excessive application of inorganic fertilizer could be a further reason affecting the status of soil properties. Overall, soil physicochemical properties indicated poor conditions for agriculture systems, thereby, careful soil management is the primary solution.

Impact of crop residue burning on physico-chemical properties of agricultural soil of Sagar district, Madhya Pradesh, India

Impact of crop residue burning on physico-chemical properties of agricultural soil of Sagar district, Madhya Pradesh, India

Long‐term combined subsoiling and straw mulching conserves water and improves agricultural soil properties

AbstractSubsoiling and straw mulching are two techniques that conserve soil water and improve the sustainability of agricultural production. However, the benefits to soil sustainability of combining subsoiling with straw mulching under intensive rotation between wheat and maize remain uncertain. We conducted a field experiment to determine the long‐term impacts of conventional tillage with straw mulching (CS), and subsoiling with straw mulching (SS), on soil macropore characteristics (>160 μm), soil aggregate characteristics, and soil hydraulic parameters at 0–100 cm depths. Results indicate that SS increased the mean macropore number (66.9%), macroporosity (93.5%), pore circularity (3.5%), field moisture capacity (11.8%), saturated moisture content (21.4%), available soil moisture content (24.1%), and the saturated hydraulic conductivity (39.3%) in the shallowest 50 cm of soil, and total organic carbon content (34.5%) and soil labile organic carbon (20.2%) in the shallowest 30 cm of soil, compared to CS. Compared with CS, SS was more effective at increasing the proportion of aggregates larger than 0.25 mm in the top 20 cm of soil and decreasing the proportion of aggregates smaller than 0.25 mm in the top 30 cm of soil. Correlations between soil organic carbon and various soil physical properties under different practices suggest that SS has larger causative effects on soil physical properties than CS. Therefore, SS is recommended over CS.

Satellite based assessment of agronomically important properties of agricultural soils with consideration of their surface state

Satellite data have been used for a long time to assess various properties of arable soils. At the same time, there are certain difficulties associated with the fact that a number of agronomically important soil properties do not directly affect spectral reflectance of their surface, which complicates the remote assessment of such properties. In addition, to obtain reproducible models, it is necessary to take into account the state of the open soil surface during the survey. The aim of the study was to demonstrate a method for detecting agronomically important properties of arable soils based on Landsat 8-9 OLI satellite data and including information about the state of their open surface using the example of a test field in the Serebryano-Prudsky district of the Moscow region. Depending on the soil property, R2cv of the models developed based on Landsat 8-9 OLI satellite data varied from 0.57 to 0.91. The best models with R2cv>0.8 were obtained for organic matter and properties higly correlated with it such as the content of exchangeable calcium and magnesium cations, the content of total nitrogen, pH of water and salt extracts. The involvement of information on the state of the open surface of arable soils for most properties made it possible to obtain models of higher quality and predictive ability, regardless of the survey period. Based on the models obtained, maps of the spatial variation of agronomically important properties of arable soils were constructed as part of the demonstration of the method. The resulting models can be used for remote monitoring of the analyzed properties of arable soils of the test field. At the same time, for such properties as the content of exchangeable potassium and phosphorus compounds, it is necessary to search for the approaches that will take into account their high variability, as well as to perform a prior assessment of the informativity of the survey periods in which the open soil surface is not transformed.

Manure application followed by biochar application increases plant production regardless of soil dehydrogenase activity

AbstractBiochar is obtained by the pyrolysis of biomass, and contains abundant carbon and minerals. Biochar supplementation of soils can greatly improve soil health and quality, but these beneficial effects typically develop slowly over time. Depending on the quality of the biochar and the soil to which it is applied, it may take years before positive effects are apparent. This is because organic substances are slowly sorbed onto the biochar over time, and the biochar eventually becomes part of the sorption complex of the soil. It is therefore advisable to apply biochar together with some organic material. We examined the effect of co‐application of different doses of biochar with manure on soil dehydrogenase activity (DHA), soil oxidizable carbon (COX), cumulative soil respiration, soil buffering capacity, the soil exchange reaction (pH/KCl) and the production yield of winter rape seeds. We also determined seed production when artificial granular fertilizers were added to biochar and manure. The results showed that the application of biochar and manure significantly increased grain yield, DHA, the soil exchange reaction and cumulative respiration. Thus, application of biochar with organic material can increase seed yield and some properties of agricultural soils. However, the positive effect of biochar on seed yield was not directly proportional to biochar dose, in that the seed yield was lower for a biochar dose of 45 t/ha than 30 t/ha.

Assessing the effect of arable management practices on carbon storage and fractions after 24 years in boreal conditions of Finland

Soil organic matter (SOM) plays an important role in soil functions that are crucial for sustainable agriculture. Understanding how agricultural management and soil properties affect SOM in different soil depths would aid in maintaining and increasing SOM throughout the soil profile. We sampled a 24 year-old cultivation field experiment with organic and conventional cropping systems, and an adjacent unmanaged meadow to 70 cm soil depth to assess the total organic carbon (OC) stocks and the distribution of OC into mineral-associated (MAOM), particulate (POM) and dissolved (DOM) organic matter. We found that >83% of the soil OC was in the MAOM fraction, and that the distribution of OC across the MAOM, POM and DOM within a soil depth was not strongly affected by soil management. Largest OC stocks (169 t ha−1) together with the largest plant root biomass was found in the unmanaged meadow, which highlights the potential of deep-rooting plants in sequestering OC into the soil. The OC saturation state of the soil was assessed based on the clay to OC ratio and Hassink's Equation (Hassink 1997). Hassink's Equation seemed to underestimate the MAOM accrual capacity of these soils and thus overestimated soil OC saturation state, whereas the clay to OC ratio indicated potential for OC accrual in all soil depths except for the meadow topsoil. These varying results suggest that the applied metric should be soil type and -depth specific. We also determined the contribution of clay content and aluminum and iron oxides in explaining the amount of total OC, MAOM-C and POM-C. In contrast to the aluminum and iron oxides, clay was not well correlated to any of the OC fractions below the 20 cm depth, suggesting that estimating the OC accrual potential of the deeper soil should not be based on the soil texture alone. Our results indicate that aluminum and iron oxides can play an important role in transporting and stabilizing of OC in the soil profile.

Implementing Cloud Computing for the Digital Mapping of Agricultural Soil Properties from High Resolution UAV Multispectral Imagery

The spatial heterogeneity of soil properties has a significant impact on crop growth, making it difficult to adopt site-specific crop management practices. Traditional laboratory-based analyses are costly, and data extrapolation for mapping soil properties using high-resolution imagery becomes a computationally expensive procedure, taking days or weeks to obtain accurate results using a desktop workstation. To overcome these challenges, cloud-based solutions such as Google Earth Engine (GEE) have been used to analyze complex data with machine learning algorithms. In this study, we explored the feasibility of designing and implementing a digital soil mapping approach in the GEE platform using high-resolution reflectance imagery derived from a thermal infrared and multispectral camera Altum (MicaSense, Seattle, WA, USA). We compared a suite of multispectral-derived soil and vegetation indices with in situ measurements of physical-chemical soil properties in agricultural lands in the Peruvian Mantaro Valley. The prediction ability of several machine learning algorithms (CART, XGBoost, and Random Forest) was evaluated using R2, to select the best predicted maps (R2 > 0.80), for ten soil properties, including Lime, Clay, Sand, N, P, K, OM, Al, EC, and pH, using multispectral imagery and derived products such as spectral indices and a digital surface model (DSM). Our results indicate that the predictions based on spectral indices, most notably, SRI, GNDWI, NDWI, and ExG, in combination with CART and RF algorithms are superior to those based on individual spectral bands. Additionally, the DSM improves the model prediction accuracy, especially for K and Al. We demonstrate that high-resolution multispectral imagery processed in the GEE platform has the potential to develop soil properties prediction models essential in establishing adaptive soil monitoring programs for agricultural regions.

Gyttja as a Soil Conditioner: Changes in Some Properties of Agricultural Soils Formed on Different Parent Materials

Organic matter is essential in improving the physical, chemical and biological properties of soils. Thus, the organic matter is widely considered a crucial indicator of environmental quality and biodiversity. In this study, the effect of gyttja addition as a soil conditioner on some physical and chemical properties of soils formed on volcanic and serpentine parent materials was investigated. The layout of the incubation study was randomized plots with 3 replications and the study lasted for 8 months to determine the value of gyttja in improving soil quality in two different parent materials. The results showed that pH, EC, total CaCO3, soil organic matter (SOM), wet aggregate stability (WSA), structural stability index (SSI), Ca-ex, Mg-ex, Fe-ex and P-av values of volcanic soils were significantly increased with increasing gyttja addition rates, while dispersion ratio (DR), Cu-ex and Cd-ex values were decreased. Likewise, pH, total CaCO3, SOM, WSA, SSI, Ca-ex and P-av values of serpentine soils were increased with increasing gyttja rates, while DR, Mg-ex, Fe-ex, Cd-ex, Ni-ex, Mn-ex, Cu-ex and Zn-ex values were decreased. The changes in the values of soil properties were statistically significant. The results demonstrated that gyttja addition overall decreased the erosion susceptibility and heavy metal contents of serpentine and volcanic soils. Moreover, the gyttja addition ameliorated some of the chemical soil properties. Therefore, gyttja could be suggested as a soil conditioner in the remediation of problematic soils.

Temporal variability in organic amendment impacts on hydro‐physical properties of sandy agricultural soils

AbstractOrganic amendments (OAs) can improve the hydro‐physical properties of a soil and thereby potentially enhance the resilience of agricultural systems to droughts and floods. An OA's contribution to this resilience, however, depends on the timeliness of its impacts, as soil improvements should be achieved when droughts are most frequent or flood risks are greatest. Yet little is known regarding the temporal variability of OA impacts or the influence of OA quantity and quality thereupon. In this research, therefore, we investigated at two agricultural sites the temporal variability of improvements in soil bulk density, aggregate stability, infiltration capacity and water retention after the application of compost, farmyard manure, bokashi, a selection of organic residues from landscape maintenance, and a combination of these residues with manure. Results showed that, depending on management practices and soil type, OAs decrease bulk density by up to 9.8%, increase infiltration capacity by up to 108.1%, aggregate stability by up to 60.0%, and water retention by up to 77.8% relative to unamended controls within 3 years of repeated application. However, the magnitude of these improvements varies up to 96% between seasons, depending on the soil property and OA treatment. On average, for all treatments, impacts relative to the control varied between different seasons by 5% for bulk density, 47.1% for infiltration capacity, 22.6% for aggregate stability, and 26.3% for water retention. When offsetting OA nutrient differences with mineral fertilizers, this variability showed a stronger correlation to differences in OA application quantity than quality (i.e., chemical composition). Results suggest that disregarding temporal variability in OA impacts can result in an inaccurate valuation of OAs as either effective or ineffective in improving soil resilience, given that impacts may, instead of their frequently presumed persistency, actually be highly transient or lagged. Our findings highlight the importance of considering the potential intra‐annual variability of OA impacts on soil hydro‐physical properties when designing OA application strategies to ameliorate the effects of specific seasonal climatic challenges.

Laboratory evaluation of infrared and ultrasonic range-finder sensors for on-the-go measurement of soil surface roughness

Soil surface roughness (SSR) is strongly influenced by agricultural activities and soil properties. However, measuring SSR is tedious and time-consuming, especially under stationary conditions. This work was conducted with laboratory measurements of SSR to investigate how to measure it on-the-go. Four roughness indices were examined to investigate which one provides a more representative value for measuring SSR on-the-go. Out of all indices, random roughness (RR) was selected for the next stage of the study, since it refers to the degree of fineness and pulverization of the soil. Four roughness classes of A, B, C, and D were formed with depressions of 0.5, 1, 2, and 4 cm, respectively, on the soil surface using four corrugated steel sheets. The RR was calculated for these corrugated soil surfaces using two range-finder sensors, an infrared (IR) and an ultrasonic (Ult) type. A carrier was built up to move the range-finder sensors above the corrugated soil surfaces at travel speeds of 2.6, 3.5, and 4.8 km/h. The overall averages of RR determined for IR and Ult sensors were correlated with the reference values measured using a pin-type profiler with correlation coefficients of 0.99 and 0.31, respectively. No significant differences were observed between the calculated RRs at the examined travel speeds. The depression and peaks measured using IR and Ult range-finder sensors were also compared to the reference values measured using the pin-type profiler and the results showed average correlation coefficients of 0.97 and 0.69 for IR and Ult range-finder sensors, respectively. While both range-finder sensors could thoroughly measure the distance under stationary conditions (R2 >0.99), however, only the IR sensor succeeded in measuring RR on-the-go on roughness classes A, B, C, and D. The reason may be attributed to the wider footprint of the Ult sensor. The results of this study can help predict physical properties related to SSR more quickly.

SOIL QUALITY IN ORGANIC AGRICULTURAL LAND: STUDY OF CHEMICAL ANALYSIS AND SOIL MICROBIOLOGY

Increased public awareness for a healthy diet must be balanced with successful cultivation. Organic farming system is the right choice since it leaves all non-organic components. This study aims to identify the chemical and microbiological properties of agricultural soils that apply organic systems located in Batang Buluh Village, Pematang Johar, Deli Serdang Regency, North Sumatra. Chemical analysis was carried out at Socfindo Laboratory in Medan, including testing the pH of H2O, total P and K, C Organic, N Kjehldahl, and CEC (Cation Exchange Capacity). Soil microbiological tests were carried out at Medan Regional Health Lab including gram staining tests and biochemical tests. The results of chemical analysis from the analysis of pH H2O, P and total K, Organic C, N Kjehldahl, and CEC (Cation Exchange Capacity) at the edges and middle each obtained that was pH 5 -6, soil total P content was 0.0260% up to 0.450%, available K analysis, namely 0.200% and 0.210%, organic C content obtained results of 0.970% and 0.630%, N content using the KJehldahl method was 0.150% and 0.090%, and CEC obtained results of 14.330 me/100 and 10.090 me/100 g. Related species of Bacillus contained in the soil were Gram-positive, rod-shaped, spore-forming, aerobic or facultative anaerobic, motile bacteria with peritrichous flagella.

BIODIVERSITY – A new space mission to monitor Earth ecosystems at fine scale

Imaging spectroscopy has demonstrated its interest in characterizing the biochemical, biophysical and structural properties of vegetation, natural and agricultural soils, as well as artificial surfaces. Following the Hyperion mission, new space missions have emerged (PRISMA, EnMap), or are under study (CHIME, SBG). However, one of their main limitations lies in their spatial resolution that induces a large number of mixed pixels reducing their potential for discrimination for very heterogeneous areas. The BIODIVERSITY mission aims to complement these space missions with better GSD acquisitions (typically 8-10 m) with a 5-day revisit on targeted reference sites with identified and well-located characteristics. It will thus make it possible, in particular, to answer two scientific issues that will design the instrument. The first issue concerns the spatial and temporal distribution of vegetation traits in species assemblages; these traits are associated with the resilience of terrestrial ecosystems, anthropogenic influences, and the biodiversity of ecosystems in terms of species composition and assemblages. The second issue relates to improving our knowledge of coastal areas and inland waters in terms of biodiversity, water quality and bathymetry, in order to assess the impact of human activity on their ecosytems. The scientific challenges as well as the user requirements for such a mission are presented for each application.

Potential of native and bioprocessed brewers' spent grains as organic soil amendments

IntroductionThe use of novel soil amendments and the exploitation of plant growth-promoting microorganisms are considered promising tools for developing a more sustainable agriculture in times when ensuring high-yield productions with limited resources is essential.MethodsIn this study, the potential of brewers' spent grain (BSG), the major by-product of the brewing industry, as organic soil amendment, was investigated. Bioprocessed BSG, obtained by an enzymatic treatment coupled with fermentation, together with native BSG, were used as amendments in a pot-trial. An integrated analytical approach aimed at assessing the modification of the physicochemical properties of a typical Mediterranean alkaline agricultural soil, and the plant growth-promoting effect on escarole (Cichorium endivia var. Cuartana), was carried out.ResultsThe use of biomasses led to soil organic content and total nitrogen content up to 72 and 42% higher, compared to the unamended soils. Moreover, the lower pH and the higher organic acids content doubled phosphorus availability. Although the number of leaves per plant in escaroles from pots amended with native and bioprocessed BSG did not show any difference compared to plants cultivated on unamended pots, the average fresh weight per escarole head, was higher in pots amended with bioprocessed BSG.DiscussionHence, the results collected so far encourage BSG application for agricultural purpose, while solving the problem of disposing of such abundant side stream.

Chemical and Biological Properties of Agricultural Soils Located along Communication Routes

The aim of the study was to assess the quality of agricultural soils, which accumulate additional amounts of heavy metals from fertilization and modify their bioavailability, with the use of interdependencies between their biological and chemical properties conditioned by the distance from communication routes. Our results indicated that heavy metals had an impact on enzyme activity in soils and their accumulation was significantly related to the distance from the edge of the road, location of sampling sites, date of soil sampling, and years of research. It was found that the greatest amounts of zinc, cadmium, lead, and copper were accumulated at a distance of 5–20 m from the edge of the road. The highest enrichment factor and geoaccumulation index values were recorded for Pb, followed by Zn, Cu, and Cd. Principal component analysis and regression models showed that the activities of phosphatase and dehydrogenases seem to be the best bioindicators of contamination of roadside soils used for agricultural purposes. Since their activity is related to soil’s organic carbon content, inputs of organic fertilizers and crop residues should be ensured in the agroecosystems along roadsides.

Effect of microplastics on silty loam soil properties and radish growth

Abstract Microplastics (particles of plastics <5 mm) affect the physical, biological and hydrological properties of agricultural soil, as well as crop growth. We investigated the effect of the addition of three microplastics (high-density polyethylene (HDPE), polyvinyl chloride (PVC), and polystyrene (PS)) at a concentration of 5% (w/w) to a silty loam soil on selected soil properties and growth of radish (Raphanus sativus L. var. sativus). Changes in the soil properties and radish growth in three microplastic treatments were compared with the control. Soil properties (bulk density, hydraulic conductivity, sorptivity, water repellency) were estimated for each treatment at the beginning and at the end of the radish growing period (GP). The bulk density was significantly lower in the HDPE and PVC treatments compared to the control within the measurement at the beginning of the GP and in all microplastic treatments compared to the control at the end of the GP. The values of hydraulic conductivity and water sorptivity did not show significant differences between any treatments within the measurement at the beginning of GP, but they were significantly higher in the HDPE treatment compared to the control at the end of the GP. The growth of radish was characterized by the plant biomass and effective quantum yield of Photosystem II (Y (II)). We did not find a statistically significant difference in the total biomass of radish between any of the experimental treatments, maybe due to used concentration of microplastics. The mean value of Y (II) was significantly higher in all microplastic treatments compared to control only within the last measurement at the end of the GP. A statistically significant change of Y(II) in all microplastic treatments may indicate functional shift in soil properties; however, the measured values of the soil characteristics have not shown the significant changes (except for the bulk density values in all microplastic treatments and hydraulic conductivity together with sorptivity in HDPE treatment within the measurement at the end of GP).