Soil Microbiological Properties Research Articles

АГРОХИМИЧЕСКИЕ И МИКРОБИОЛОГИЧЕСКИЕ СВОЙСТВА ПОЧВ ПОРОДНОГО ОТВАЛА БАРЗАССКОЙ ОБОГАТИТЕЛЬНОЙ ФАБРИКИ

The Barzassky district of the Kemerovo region is poorly developed by industry, but large areas of land are already subject to alienation. For the competent implementation of the process of disturbed territories recultivation, it is important to understand the degree of degradation of soil covers. Therefore, the purpose of the work was to study the agrochemical and microbiological properties of Barzassky processing factory rock dump soils. In the course of the work, soil samples from the surface layer of the dump as well as from the borders of the railway protective forest belt were studied. The studied soils of the dump are classified as slightly alkaline (average pH 7.899). The soils selected from the railway protective forest belt were subjected to acidification. The samples showed a low content of nitrogen (ammonium and nitrate – <5.0 and <2.8 mg/kg, respectively). Significant content of salinization was found. It has been established that acidification of soils in technogenically disturbed territories leads to a soil microbiota disorder and an increase of conditionally pathogenic microorganisms in them.

Effects of altitude on soil properties in coastal fog ecosystems in Morro Moreno National Park, Antofagasta, Chile

AbstractRare Pacific coast fog ecosystems are under threat from climate change and local factors. Although coastal fog is known to affect soil properties and microbial diversity, few studies on the Pacific coast have examined the specific microbiomes associated with these ecosystems. We evaluated the effects of coastal fog on the physicochemical, mineralogical, and microbiological properties of bare soils (vegetation‐free) and bulk soils (surrounding plant roots) from different altitudes in the Morro Moreno National Park (MMNP) in the Antofagasta region, Chile. We found that the temperature and relative humidity of the soil varied temporally (daily) and spatially (with altitude). We detected that soil organic matter and organic phosphorus content tended to increase with altitude, whereas the pH, electrical conductivity, and total phosphorus decreased. Our results showed that coastal fog could induce physical weathering below 300 masl and chemical weathering at the intermediate altitudes of ~400–600 masl. The biodiversity of bacteria and fungi increased considerably above 400 masl. Actinobacteria and Bacteroidetes dominated the bacteria in bare soil, and Bacteroidetes dominated the bulk soil communities at all altitudes. Ascomycota and Basidiomycota dominated the fungal community in both soil types. Moreover, the electrical conductivity and CaO content appear to be more closely associated with microbial communities from lower altitudes. In addition, the organic carbon content, humidity, and weathering index 2 (WI2) isolated some communities at 500 and 600 masl. The microbiological diversity reported in this work reflects the variable and different microbial niches comprising the MMNP environment. Linkages between soil property and microbial variations with altitude within this Northern Chilean coastal fog ecosystem were elucidated. This novel scientific knowledge contributes to global network strategies for fog ecosystem conservation, which aim to preserve the microbial niches and diversity in such soils.Highlights We studied physicochemical, mineralogical and microbiological properties in a fog ecosystem soils. The study provides valuable information from rare and unique Pacific coast fog systems. Soil properties and microbial diversity showed specific correlations, and dependence on altitude. This baseline could contribute to the creation of conservation strategies of these unique ecosystems.

Analysis of the Soil Properties of an Industrial Area in Latur

In the present work, the physicochemical analysis and microbiological properties of soil in an industrial area of latur is carried out. The soil samples were collected from industrial area of latur. The parameters of soil analysis were pH, Alkalinity, Sulphate content, total solids, Organic matter and Microbial activity. The result of pH analysis revealed that the two samples from industrial area had noticeable pH variation from that of control. The alkalinity of the polluted samples was lesser than that of control. Sulphate content and total solids were high in polluted samples compared to control. Microbial activity is very low in acidic polluted samples, where in control it was very high. Due to the presence of heavy metals the total solid content of polluted soil was high. Due to the acidity of the polluted soils the organic matter and microbial activity were less.

Biological Indicators of Soil Condition on the Kabanyolo Experimental Field, Uganda

Soil biological activity is an integral characteristic reflecting the state of soil fertility, biodiversity, and the activity of soil processes carried out by soil organisms. In Africa, studies of soil biological properties are few compared to the agrochemical research. In this paper, we present an assessment of multiple biochemical and microbiological properties of soil from an agricultural field located in the African tropical savanna. We determined basal respiration, substrate-induced respiration, C of microbial biomass, the potential activity of denitrification, nitrogen fixation activity, and estimated prokaryotic components in the soil microbial complex by quantitative PCR. Basal respiration of soils ranged from 0.77 ± 0.04 to 1.90 ± 0.23 μg C-CO2·g−1·h−1, and substrate-induced respiration ranged from 3.31 ± 0.17 to 7.84 ± 1.04 μg C-CO2·g−1·h−1. The C reserves of microbial biomass averaged 403.7 ± 121.6 μg C·g−1 of soil. The N2O emission from the upper layer on average amounted to 2.79 ng N-N2O·g−1·day−1, and the potential denitrification activity reached 745 ± 98 ng N-N2O·g−1·h−1. The number of copies of bacterial genes varied from (0.19 ± 0.02) × 108 to (3.52 ± 0.8) × 108 copies·g−1, and of archaea—from (0.10 ± 0.01) × 107 to (0.29 ± 0.01) × 107 copies·g−1 of soil. These results were in good agreement with the studies in other seasonally wet tropical regions: the biological activity was relatively low. The difference between biological indicators of the experimental field and the reference profile were insignificant except for nitrogen loss, which was higher in the ploughed field. Biological indicators strongly varied in space; we explained their heterogeneity by non-uniform management practices in the course of agrochemical field experiments in the past. The use of organic fertilisers may cause the release of climatically active gases due to intensive microbial respiration and denitrification, but the intensity of emission would strongly depend on the cultivation and management method.

Changes in soil functionality eight years after fire and post-fire hillslope stabilisation in Mediterranean forest ecosystems

Contour-felled log debris (CFD) and log erosion barriers (LEB) are two restoration practices used worldwide on hillslopes to avoid soil erosion after wildfires. Although significant work has evaluated the effectiveness of these practices on soil loss prevention, their effects on soil properties have been little researched to date. Here, the effects of CFD and LEB treatments on several physico-chemical and biological soil properties were investigated across four post-fire zones in Mediterranean forest (Sierra de Los Donceles, Spain). Results suggest that post-fire management similarly altered the recovery of microbiological soil properties and soil functionality for both CFD and LEB treatments. Post-fire management enhanced soil organic matter (SOM) and basal respiration, while suppressing soil microbial activities. SOM enhancement at our plots may have been associated with suppressed soil microbial decomposition activity due to post-fire increases in electrical conductivity. Plots with post-fire management recovered microbiological soil properties better than unmanaged burn plots, but not to the same level as nearby unburned plots. LEB and CFD may not only be effective in retaining sediments, but also in improving post-fire microbiological soil properties in comparison to unmanaged plots. However, after eight years of post-fire management, soil microbiological soil properties did not completely recover compared to unburnt areas. That is, fire may shift the development trajectory of microbiological soil properties so that they may no longer be able to return to the same unburnt conditions. Post-fire restoration plans should consider the use of LEB and CFD when aiming to aid soil-related ecosystem recovery processes after wildfires.

Effect of Charcoal on the Properties, Enzyme Activities and Microbial Diversity of Temperate Pine Forest Soils

Relict charcoal hearths (RCHs) increases soil fertility in forest ecosystems. However, the effects of RCHs on the activity and abundance of soil microorganisms remain unknown. In this paper, we analysed the impact of relict charcoal production on the soil enzymatic activity and composition of soil bacterial and fungal communities in Scots pine forests of the Manowo Forest District in northern Poland. Moreover, we determined the effect of relict charcoal production on the soil properties. Our research was conducted by comparing the physical, chemical, enzymatic and microbiological properties of charcoal-enriched and charcoal-free soils. Significant differences in physical properties were found between these two soil types in terms of their structure and water holding capacity. As expected, horizons enriched with charcoal were characterised by a significantly higher organic carbon content (4.7% on average compared to 2.2% in control horizons), and also by a considerably higher content of available phosphorus (an average of 64.07 mg·kg−1 compared to 36.21 mg·kg−1 in the control). Similarly, RCH horizons displayed a higher pH and higher contents of Ca and Na cations. These results indicated that RCH soils provided more favourable conditions for the soil microbiome, as reflected by the higher enzymatic activity and diversity of the microorganisms. Moreover, bacterial and fungal communities in RCH soils were more diverse and had greater species/genera richness, especially in the case of fungi. Members of the genus Rhodoplanes dominated the bacterial community at both RCH and non-RCH sites, followed by Streptomyces, Burkholderia, Skermanella, Tsukamurella and Candidatus Solibacter. Both culture- and next generation sequencing (NGS)-based analyses showed that soil fungal communities were dominated by Ascomycota, with Penicillium as the most abundant genus. Our results showed that hearth soils may represent a significant C pool in the forest ecosystem. This study supports the strategy of safeguarding such charcoal-enriched soils as precious C reservoirs and ecologically important biodiversity hotspots. Moreover, the application of charcoal may effectively increase the microbial diversity of forest soils, especially during the reforestation or re-cultivation of disturbed habitats.

The Contribution of Microorganisms to Soil Organic Carbon Accumulation under Fertilization Varies among Aggregate Size Classes

Long-term fertilization alters soil microbiological properties and then affects the soil organic carbon (SOC) pool. However, the interrelations of SOC with biological drivers and their relative importance are rarely analyzed quantitatively at aggregate scale. We investigated the contribution of soil microbial biomass, diversity, and enzyme activity to C pool in soil aggregate fractions (>5 mm, 2–5 mm, 1–2 mm, 0.25–1 mm, and <0.25 mm) at topsoil (0–15 cm) from a 27-year long-term fertilization regime. Compared to CK (no fertilization management), NP (inorganic fertilization alone) decreased all of the microbial groups’ biomass, while NPS and NPM (inorganic fertilization plus the incorporation of maize straw or composted cow manure) significantly reduced this negative effect of NP on microbial biomass and increased the microbial contribution to C pool. The results show that microbial variables were significantly correlated with SOC content in >0.25 mm aggregates rather than in <0.25 mm aggregates. Fungal variables (fungal, AM biomass, and F/B ratio) and enzyme activities (BXYL and LAP) in >0.25 mm aggregates explained 21% and 2% of C, respectively. Overall, organic matter addition could contribute to higher C storage by boosting fungal community and enzyme activity rather than by changing microbial community diversity in macro-aggregates.

Soil Microbiological Attributes and Soybean Grain Yield in Succession to Corn Intercropped with Forage in the Maranhão Eastern Cerrado

Soil Microbiological Attributes and Soybean Grain Yield in Succession to Corn Intercropped with Forage in the Maranhão Eastern Cerrado

Enhancing soil ecosystem services through sustainable integrated nutrient management in double rice-cropping system of North-East India

The wetland cultivation of rice is subjected to anaerobic and aerobic soil conditions causing substantial changes in the soil system. However, how long-term supplementation of organics with reduced chemical fertilizers affects microbial composition, their activities, and enzymatic activities in acid soil has not been sufficiently investigated. This research is focused on a rice-rice system after an ongoing field experiment set-up in 1977–78 at Assam Agricultural University, Jorhat, India, where 7 alternative nutrient management have been investigated to: (1) assess the effects on soil organic carbon (SOC), microbial biomass carbon, and enzymatic activity in acid soil; (2) identify and discuss the most suitable treatment combinations of organic and chemical fertilizers to enhance soil ecosystem services (SES). Accordingly, we analysed the soil microbiological properties as affected by the 32 years of continuous integrated nutrient management (INM) practices and also evaluated the INM treatments in terms of SES. Results revealed that the soil microbial biomass carbon significantly varied across the treatments from 129.4 to 412.1 µg g−1 which comprises 2.4 to 4.4% of the SOC. The highest bacterial count (8.95 log cfu g−1 soil) was recorded in RDF + Azolla treatment, whereas fungal count was the maximum (7.47 log cfu g−1 soil) in RDF + FYM treatment. All the enzymatic activities responded significantly to the INM practices, but the trend of response was different for different enzymes. The highest dehydrogenase (223.6 µg TTF g−1 soil 24 h−1) and urease (4.1 μg NH4-N g−1 soil 2 h−1) activities were recorded in RDF + Azolla, while phosphomonoeaterase (337.4 μg p-nitrophenol g−1 soil h−1) and fluorescein diacetate hydrolysis (10.0 μg fluorescein g−1 soil h−1) activities were found to be the maximum in RDF + FYM. The microbial and enzymatic activities decreased significantly in the control after 32 cycles of rice-rice cropping. In this study, a significant positive statistical correlation of all the microbiological properties with soil pH, soil organic carbon and grain yield of crops were recorded. Finally, the different soil properties under the different nutrient treatments have been discussed in terms of SES provision, highlighting that the most sustainable treatments have resulted in RDF + FYM, RDF + RS and RDF + Azolla.

Effect of biomass fly ashes from fast pyrolysis bio-oil production on soil properties and plant yield

A globally increased demand for fuels and environmental concerns regarding fossil sources call for sustainable alternatives. Fast pyrolysis is a promising approach for converting different types of biomass to renewable Fast Pyrolysis Bio-Oil (FPBO) that can be used for heating, power generation and mobility. Side-products emerging from the process include low calorific gases and charcoal. Both are further combusted to generate energy for the process. From the charcoal, the process leaves behind fly ashes (FAs) that contain macro- and micronutrients. In this regard, FPBO-FAs might present valuable soil fertilizers, but also bear the risk of soil heavy metal (HM) contamination. In this study, the risk and potential benefit of FPBO-FAs derived from three different biomass sources (bark, forest residue and Miscanthus sp.) as soil amendments was tested. Twice, in autumn 2017 and 2018, FPBO-FAs were applied to the field (500 kg ash ha−1 y−1) in a grassland experiment. Neither physico-chemical and microbiological soil properties nor plant yield were affected following FPBO-FAs application. Seasonal differences and changes from year to year, however, were evident, both for some soil and plant properties. The lack of effects on (i) plant yield, (ii) soil microbiological and physicochemical properties, (iii) heavy metal concentrations in soil and plant suggest that the product may safely be applied. The fact that these field-trial results are in discordance with previous greenhouse trials suggest, however, that long-term trials would be needed.

ECONOMIC ANALYSIS OF THE VALUE OF SOILS IN THE NORTH OF EUROPEAN RUSSIA IN DIFFERENT LAND USE SCENARIOS

The article reports the results of a comprehensive RFBR project which combined research in the fields of soil science, forestry, botany, ecology, microbiology, and economics. The question of monetization of ecosystem services and the challenges that occur when interpreting the results based on the integration of natural sciences and economic approaches in the study of this problem are investigated. This discussion highlights the need for a better statistical tool to shift the focus in measuring economic phenomena to sustainable development. We propose a system of mappings based on model (operational) relationships between functional and structural features of the soil and external data, each of which is characterized by a certain set of interacting processes. The theoretical and empirical background for studying changes in the land-use regime and the carbon balance in ecosystems is explored. Changes in the morphological, basic agrochemical and microbiological properties of soils, as well as the reserves of organic carbon and microbial carbon in the top-meter layer of soil in various land-use scenarios are shown. The total carbon budget was estimated for sites with different land uses on genetically similar soils in the middle-taiga subzone of European Russia. Indicators of the state of the soil system, which can be used for the economic assessment of landuse change are proposed.

Soil attributes as indicators of the stabilization process of erosion in gullies at different formation stages in the southeast region of Brazil

Water erosion is one of the main forms of soil degradation, causing economic, environmental, and social damage. This study evaluated the effects of different formation stages of gullies (initial - IG; juvenile- JG; mature - MG; and senile - SG) on the chemical, organic carbon and microbiological attributes of soil, using a secondary forest (SF) and two areas of pasture as references in the “Mar de Morros” environment of the Brazilian Atlantic Forest biome. Soil samples (depth 0–0.05 m) were collected at the end of the rainy and dry seasons. Gullies in different stages of formation promote a decrease in soil fertility and modification of microbiological attributes, particularly when compared with secondary forest areas. Reductions of over 60% in total organic carbon (TOC), oxidizable organic carbon (POXC), FDA activity, β-glycosidase, acid phosphatase, C and N from microbial biomass, basal soil respiration (BSR) and glomalin-related soil protein (GRSP) were observed in gullies in early (IG) and intermediate (JG and MG) stages when compared to SF. It was found that the effect of erosion on soil chemical and microbiological attributes is more intense in gullies in the initial and intermediate stages compared with those in the senile stage (SG). Using multivariate PCA, the microbiological and chemical attributes of the soil are discriminated between gullies with distinct formation stages. Chemical attributes, TOC, POXC, FDA activity, β-glycosidase, acid phosphatase, MBC and MBN, BSR, and GRSP are good indicators for evaluating the process of erosion stabilization in gullies.

Soil microbiological properties in livestock corrals: An additional new line of evidence to identify livestock dung

In the article we have attempted to expand the list of methods for identification of livestock dung produced by cattle kept in corrals at archaeological sites on the basis of an integrated approach combining soil microbiology and chemistry methods. A multidisciplinary study of soils in the stone corrals in the Kislovodsk basin (North Caucasus, Russia) was carried out. The time of corral creation was from first millennium BC to the first millennium AD. The study of soils from the corrals showed that the most informative microbiological indicators for identifying livestock keeping locations at archaeological sites are the activity of enzymes involved in the phosphorus cycle and the abundance of thermophilic microorganisms. A significant increase in the phosphate content can be observed in soils of corrals, especially in soils of the occupation layer; however, high enzyme activity and the abundance of thermophilic microorganisms are reliable indicators of cattle dung accumulation and may be used as indicators of ancient corrals.

Microbiological indicators of soil quality predicted via proximal and remote sensing

This work sought to predict soil microbiological attributes based on soil fertility and texture, elemental contents determined by portable X-ray fluorescence spectrometry, and terrain attribute data with and without addition of season (dry or rainy) and phytophysiognomy as auxiliary predictors. Soil samples were collected in both seasons in four phytophysiognomies. Analyses for prediction of basal soil respiration, microbial biomass carbon, metabolic quotient, and microbial quotient were performed. Terrain attributes, total elemental concentrations obtained by portable X-ray fluorescence spectrometry, soil fertility and texture as well as phytophysiognomy and season were used as predictor variables. Prediction models were created via conditional random forest algorithm and validated with leave-one-out cross-validation through coefficient of determination (R2), root mean square error, mean absolute error and ratio percent deviation. The best results were delivered when phytophysiognomy and season were included as predictors. Metabolic quotient, microbial quotient, microbial biomass carbon and basal soil respiration achieved the best prediction using only soil fertility and texture data (R2 = 0.79, 0.66, 0.65, 0.91, respectively). Predictions of basal soil respiration and metabolic quotient using only terrain data achieved R2 values of 0.91 and 0.73, respectively. Elemental concentrations determined by portable X-ray fluorescence spectrometry reasonably predicted two microbiological attributes. It is possible to adequately predict these four microbiological attributes both locally and spatially through terrain and soil properties data. We encourage further investigations on prediction of these and other microbiological attributes under different environmental conditions and at shorter spatial and temporal scales.

Soil CO2 emission and soil attributes associated with the microbiota of a sugarcane area in southern Brazil

The spatial structure of soil CO2 emission (FCO2) and soil attributes are affected by different factors in a highly complex way. In this context, this study aimed to characterize the spatial variability patterns of FCO2 and soil physical, chemical, and microbiological attributes in a sugarcane field area after reform activities. The study was conducted in an Oxisol with the measurement of FCO2, soil temperature (Ts), and soil moisture (Ms) in a regular 90 × 90-m grid with 100 sampling points. Soil samples were collected at each sampling point at a depth of 0–0.20 m to determine soil physical (density, macroporosity, and microporosity), particle size (sand, silt, and clay), and chemical attributes (soil organic matter, pH, P, K, Ca, Mg, Al, H + Al, cation exchange capacity, and base saturation). Geostatistical analyses were performed to assess the spatial variability and map soil attributes. Two regions (R1 and R2) with contrasting emission values were identified after mapping FCO2. The abundance of bacterial 16S rRNA, pmoA, and nifH genes, determined by real-time quantitative PCR (qPCR), enzymatic activity (dehydrogenase, urease, cellulase, and amylase), and microbial biomass carbon were determined in R1 and R2. The mean values of FCO2 (2.91 µmol m−2 s−1), Ts (22.6 °C), and Ms (16.9%) over the 28-day period were similar to those observed in studies also conducted under Oxisols in sugarcane areas and conventional soil tillage. The spatial pattern of FCO2 was similar to that of macropores, air-filled pore space, silt content, soil organic matter, and soil carbon decay constant. No significant difference was observed between R1 and R2 for the copy number of bacterial 16S rRNA and nifH genes, but the results of qPCR for the pmoA gene presented differences (p < 0.01) between regions. The region R1, with the highest FCO2 (2.9 to 4.2 µmol m−2 s−1), showed higher enzymatic activity of dehydrogenase (33.02 µg TPF g−1 dry soil 24 h−1), urease (41.15 µg NH4–N g−1 dry soil 3 h−1), amylase (73.84 µg glucose g−1 dry soil 24 h−1), and microbial biomass carbon (41.35 µg C g−1 soil) than R2, which had the lowest emission (1.9 to 2.7 µmol m−2 s−1). In addition, the soil C/N ratio was higher in R2 (15.43) than in R1 (12.18). The spatial pattern of FCO2 in R1 and R2 may not be directly related to the total amount of the microbial community (bacterial 16S rRNA) in the soil but to the specific function that these microorganisms play regarding soil carbon degradation (pmoA).

Carbon and nitrogen stocks and microbiological attributes of soil under eucalyptus cultivation in the Pampa biome of southern Brazil

In the south of Brazil, the intensification of eucalyptus planting can impact the local biome, characterized by grasslands that extends to Uruguay and Argentina. Thus, the objective of the study was to evaluate changes in soil carbon, nitrogen and their labile fractions and soil microbiological attributes due to the introduction of eucalyptus cultivation in the Pampa biome. The soils evaluated were Eutric Regosol (RG), Haplic Lixisol (LX), Dystric Leptosol (LP) and Pellic Vertisol (VR). For this, areas of homogeneous cultivation of Eucalyptus saligna (7 years old) and areas of grassland (native vegetation) were selected. Physical granulometric fractionation of soil organic matter (SOM) was performed in the 0–5, 5–10 and 10–15 cm soil layers, quantifying levels, stocks and distribution of total organic carbon (TOC) and total nitrogen (TN) in the labile and associated with minerals fractions, and the carbon management index (CMI) was calculated. In the 0–5 and 5–10 cm soil layers, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), basal soil respiration, metabolic coefficient, MBC / TOC, MBN / TN, MBC / MBN ratios were also evaluated. Eucalyptus cultivation increased the TOC and POC carbon stocks by 8.7 and 21.7%, respectively (0-15 cm) in compared to grassland. It was also observed that the cultivation of eucalyptus increased 6.7% and 26.0% the stocks of TN and PN, respectively, compared to grassland in the pampa biome. Carbon stocks associated with minerals were not affected by eucalyptus cultivation. The cultivation of eucalyptus increased the basal respiration and the microbial biomass carbon in relation to grassland and there is a reduction of microbial biomass nitrogen in the soil. Thus, the cultivation of eucalyptus in the Pampa biome in southern Brazil demonstrates that it is a forest crop that can contribute to the increase in total and labile carbon stocks and also the biomass and microbial activity of the soil, which are important indicators of assessment of soil quality.

Influence of carbonised biomass on soil improvement, increase in yield of agricultural crops and mitigation of climate change implications

The relevance of the study is conditioned by the need to develop and implement new technological solutions for tillage, which will improve the soil properties. The purpose of this study is to assess the impact of carbonised biomass on the properties and quality of soils, as well as the associated environmental consequences. The tasks addressed by the study were solved with the help of scientific theoretical methods: analysis, systematisation and generalisation of results. The scientific works related to the problem of the influence of carbonised biomass on soil quality were analysed in this paper. An assessment of the effectiveness of its use as an organic ameliorant and its effect on improving the agronomic properties of soils, their fertility, and on the ecological situation has been carried out. It is substantiated that the use of obsolete agricultural technologies during agricultural activities and their violation have a negative impact on soil fertility and increase in greenhouse gases in the atmosphere. It is argued that this could lead to a global food crisis. It has been emphasised that due to the use of biochar as an organic ameliorant the physical and microbiological properties of soils are improved, the availability of nutrients is optimised, and the content of toxic elements is reduced. It is shown that carbonised biomass has a positive effect on yields and also helps to reduce greenhouse gas emissions into the atmosphere. The main current problems that exist in Ukraine regarding the use of soil improvement technology with the help of carbonised biomass are identified. The ways of their solution for the further development of these technologies and their implementation in the agro-industrial sector are proposed. The practical value of the study consists in determining the effectiveness of using carbonised biomass when it is introduced into the soil to improve its quality, increase crop yields, and slow down climate change

Effect of Continuous Intensive Cultivation on the Chemical and Microbiological Properties of Oxic Dystrandept Soils in the Western Highlands of Cameroon

Soil fertility indices are well documented as they are directly related to land use and productivity. However, the effect of continuous intensive cultivation on the evolution of soil fertility is still poorly documented. The aim of this study was thus to assess the effect of continuous intensive cultivation on the chemical and microbiological properties of Oxic Dystrandept soils in the Western Highlands of Cameroon. Composite soil samples were taken between 0-15 cm depths on farmlands that have been subjected to continuous intensive cultivation for one, five and ten years meanwhile samples from plots that have never been cultivated served as control. The main results revealed that the ammonium contents dropped abruptly (86%-wt) from the first year of cultivation. The organic carbon (OC) content decreased from 1.81 ± 0.14 %-dm (in control) to 1.69 ± 0.09 % after one year, 1.66 ± 0.10 % after 5 years and 1.58 ± 0.07 % after 10 years. Compared to the control, available phosphorus (P) showed a 13 %-wt drop after one year, 46 % after 5 years and 85 % after 10 years. Dehydrogenase activity showed a 42 % decrease after one year, 50 % after five years and 73 % after 10 years. The other parameters were not significantly different (P&lt;0.05) amongst treatments. Decline of soil productivity was undoubtedly related to the decrease of OC, P, microbial activity and ammonium with continuous intensive cultivation. Thus, management strategies for improved crop production should include selection suitable cropping systems and chemical methods. Keywords: Continuous intensive cultivation, enzymatic activities, soil chemical properties, Oxic Dystrandept, Cameroon western highland

The Effect of Petroleum-Derived Substances and Their Bioremediation on Soil Enzymatic Activity and Soil Invertebrates

Petroleum-derived substances (PDSs) as main pollutants of the natural environment can negatively affect the microbiological, biochemical, and biological properties of agricultural soils and, consequently, plant production. The present study aimed to determine the after-effect of PDSs such as petrol, used engine oil, and diesel fuel on the activity of selected soil enzymes (phosphatase, dehydrogenase, and urease) and on the occurrence of soil invertebrates. Moreover, changes in the analyzed parameters in response to bioremediation of the polluted soil by using ZB-01 preparation were investigated. The field experiments were performed four- and five-years post contamination. The results showed that even after five years, PDSs significantly modified the activity of soil enzymes; however, this effect was often varied, depending on the pollutant, enzyme, and time after soil contamination. Dehydrogenase seems to be a good indicator of soil contamination with PDSs, particularly diesel fuel. Engine oil and diesel fuel limited still the occurrence of soil invertebrates, particularly Collembola from the families Hypogastruidae, Isotomidae, and Entomobryidae, even after four and five years of contamination. This finding suggests the usefulness of these organisms in assessing soil pollution and in monitoring the progress of bioremediation. The effect of ZB-01 biopreparation on the activity of selected enzymes was varied. Its effect on the occurrence of soil invertebrates was usually beneficial, which was evident in diesel fuel-contaminated soil.

Microbial features of newly-formed soils of disposal fields from sugar refineries

Newly-formed soils of wastewater disposal fields from two sugar refineries in forest-steppe zone (Kursk region, European Russia) were studied. Among factors of soil formation on sugar wastewater lagoons the geochemical influence of wastewater mixed with diluted filtration and transport-washing sludge stands out. We have revealed key physico-chemical and microbiological properties of such soils formed under different moisture regimes, substrates, vegetation, and duration of use. Compared to conditionally background soils (Luvic (Anthric) Chernozems), the newly formed soils show shift of pH values to alkaline ones, carbonation, increase of soil organic carbon, growth in mobile forms of phosphorus, potassium and nitrogen. Microflora in studied soils is identical in composition to background soils, but it differs significantly in structure. In soils formed in the decommissioned wastewater lagoons of an active sugar refinery, a higher number of bacteria with low participation of Micromycetes and Actinomycetes was noted, which indicates active destruction of organic matter. In soils of the recultivated and completely abandoned sugar wastewater lagoons indicated as Calcaric Someric Phaeozem, a higher number of Actinomycetes was noted than in the background soils.