Uncultivated Soils Research Articles

Variability in soil organic carbon pools in different land use systems in the north-eastern region of India

The current study was carried out during 2020 to 2022, at Horticulture Research Centre (HRC), Nagicherra, Agartala, Tripura to assess and compare the effects of various land use systems, including bamboo, tea, mango, lemon, rice-rice, wheat-millet, okra-onion and uncultivated soils, on soil organic carbon (SOC) dynamics. SOC is a critical component of terrestrial ecosystems, influencing soil health, fertility and carbon sequestration potential. The NEH region of India, Tripura characterized by its diverse agro-ecological zones and land use systems (LUS), presents a unique opportunity to investigate the various land use regimes' effects on SOC pools. Walkley and Black carbon (WBC) significantly vary among the selected LUS, ranging from 7.14–12.48 g/kg, with the maximum values in tea LUS. In 0–30 cm depth, very labile C (CVL) pools are very variable among the selected LUS (2.04–5.35 g/kg), which is the highest in tea and mango compared to the uncultivated system. The C pools in selected LUS indicated the deviation depth and land use pattern. Lability index (LI) varies from 1.50–1.63 and 1.40–1.74 in 0–30 cm and 30–60 cm depth, respectively. Carbon pool index (CPI) assessed highest in tea LUS, 1.78 and 2.1 from 0–30 and 30–60 cm, respectively. Carbon management index (CMI) was higher in selected LUS compared to uncultivated system.

Biosynthetic gene clusters from uncultivated soil bacteria of the Atacama Desert.

Soil microorganisms mediate several biological processes through the secretion of natural products synthesized in specialized metabolic pathways, yet functional characterization in ecological contexts remains challenging. Using culture-independent metagenomic analyses of microbial DNA derived directly from soil samples, we examined the potential of biosynthetic gene clusters (BGCs) from six bacterial communities distributed along an altitudinal gradient of the Andes Mountains in the Atacama Desert. We mined 38 metagenome-assembled genomes (MAGs) and identified 168 BGCs. Results indicated that most predicted BGCs were classified as non-ribosomal-peptides (NRP), post-translational modified peptides (RiPP), and terpenes, which were mainly identified in genomes of species from Acidobacteriota and Proteobacteria phyla. Based on BGC composition according to types of core biosynthetic genes, six clusters of MAGs were observed, three of them with predominance for a single phylum, of which two also showed specificity to a single sampling site. Comparative analyses of accessory genes in BGCs showed associations between membrane transporters and other protein domains involved in specialized metabolism with classes of biosynthetic cores, such as resistance-nodulation-cell division (RND) multidrug efflux pumps with RiPPs and the iron-dependent transporter TonB with terpenes. Our findings increase knowledge regarding the biosynthetic potential of uncultured bacteria inhabiting pristine locations from one of the oldest and driest nonpolar deserts on Earth.IMPORTANCEMuch of what we know about specialized metabolites in the Atacama Desert, including Andean ecosystems, comes from isolated microorganisms intended for drug development and natural product discovery. To complement research on the metabolic potential of microbes in extreme environments, comparative analyses on functional annotations of biosynthetic gene clusters (BGCs) from uncultivated bacterial genomes were carried out. Results indicated that in general, BGCs encode for structurally unique metabolites and that metagenome-assembled genomes did not show an obvious relationship between the composition of their core biosynthetic potential and taxonomy or geographic distribution. Nevertheless, some members of Acidobacteriota showed a phylogenetic relationship with specific metabolic traits and a few members of Proteobacteria and Desulfobacterota exhibited niche adaptations. Our results emphasize that studying specialized metabolism in environmental samples may significantly contribute to the elucidation of structures, activities, and ecological roles of microbial molecules.

Rhizosphere-associated microbiota of Canavalia ensiformis in sulfentrazone bioremediation

The objective of this study was to determine the efficiency of the microbial rhizosphere (Canavalia ensiformis) in the phytoremediation of sulfentrazone using quantification methods (CO2 evolution, microbial biomass carbon, and metabolic quotient) and identification of bacteria (PCR-DGGE technique). The experiment was conducted in a completely randomized design, in a 2x4 factorial scheme, with four replications. The treatments were composed of rhizospheric soil (cultivated with C. ensiformis) and non-rhizosphere soil (uncultivated soil); and four levels of contamination by sulfentrazone (0, 200, 400, and 800 g ha−1 a.i.). The microbiota associated with the rhizosphere of C. ensiformis efficiently reduced sulfentrazone residues in the soil, with better performance at the dose of 200 g ha−1 a.i. Using the PCR-DGGE technique allowed the distinction of two profiles of bacteria in the rhizospheric activity of C. ensiformis. The second bacterial profile formed was more efficient in decontaminating soil contaminated with sulfentrazone residue. The microbiota associated with the rhizosphere of C. ensiformis has an efficient profile in decontaminating soils with residues equivalent to 200 g ha−1 a.i. the herbicide sulfentrazone.

ТРАНСФОРМАЦИЯ ПЛОДОРОДИЯ ПОЧВ ЗАЛЕЖЕЙ ЛЕСОСТЕПНОЙ ЗОНЫ ПРИ РАЗЛИЧНОМ НАПРАВЛЕНИИ ИХ ИСПОЛЬЗОВАНИЯ

The purpose of research is to provide a comprehensive comparative assessment of the fertility of gray fallow soils in the forest-steppe zone of the Krasnoyarsk Region, overgrown with forest, used for hayma-king and re-developed into arable land. The studies were conducted in 2007–2020 in the Krasnoyarsk and Achinsk-Bogotol forest-steppe on gray soils of fallow lands no longer used for agricultural purposes. Stu-dies were carried out to assess the indicators of the potential and effective fertility of gray soils of fallow lands of the Krasnoyarsk and Achinsk-Bogotol forest-steppe with their various post-agrogenic use. It has been established that forests regenerated on fallow lands do not lead to degradation of soil fertility, especially in terms of the content of humus and agronomically valuable aggregates. The emerging forest litter and tree litter accelerate the accumulation of organic matter, a source of humus. There is weak spatial va¬riation in most indicators of effective and potential fertility in soils under regenerating forest compared to pure fallow lands. With the re-involvement of fallow land into arable land, nitrification somewhat increases, spatial variation in soil properties decreases, and the content of humus and absorbed bases decreases. The structural composition of the soils of all study objects is characterized as excellent (ACF 88–77 %) with an insignificant value of the coefficient of variation of fractions (4–7 %). When reclaiming fallow lands into arable land, the proportion of the blocky fraction is significantly reduced. The spatial variability of the structural composition of soils in fallow lands and hayfields is higher than on arable land, which is asso¬ciated with the “clumpiness” of the ground cover and root system of plants on uncultivated soils. In terms of fertility, post-agrogenic gray soils used for haymaking occupy an intermediate position between clean fallow lands and those overgrown with forest. The productivity of the phytomass of fallow lands, arable land and hayfields in the Krasnoyarsk and Achinsk-Bogotol forest-steppe is more closely correlated with the indicators of the potential fertility of post-agrogenic gray soils. In most cases, the values of the correlation coefficients are closer between phytomass reserves and indicators of effective fertility in the Achinsk-Bogotol forest-steppe, which is associated with more favorable hydrothermal conditions in this research area and optimal water-physical properties.

Irrigation-Initiated Changes in Physicochemical Properties of the Calcisols of the Northern Part of Fergana Valley

Agriculture in Central Asia and in the Fergana Valley in general strongly depends on irrigation and drainage of agricultural lands. The Fergana Valley includes about 45% of the irrigated area in the Syr Darya River basin. Active use of irrigation in agriculture can lead to changes in the soil’s natural composition, as well as pollution and changes in the soil’s physical and chemical properties. Soil degradation in the process of irrigation can lead to a decrease in crop yields and, as a consequence, to a decrease in food security in the region. In this study, a comparative analysis of three main types of Calcisols (Dark, Light, and Typical) before (uncultivated soil) and after agricultural use (surface-irrigated agricultural soil) was carried out. Irrigation leads to increment of SOC stocks in Typical (from 113.8 to 126.3 t/ha) and Light (from 62.8 to 100.1 t/ha) Calcisols and to decreasing of SOC stocks in Dark Calcisols (from 160.1 to 175.3 t/ha). In general, the content of biophilic elements (SOC and TN) is lower in irrigated soils, and their distribution in the soil profile is close to the functional relationship (r2 0.98 to 0.99). In uncultivated Calcisols, the profile distribution of SOC and TN is more heterogeneous (r2 0.67 to 0.97). Changes in the humification processes of soil organic matter are also identified; in soils after irrigation the carbon ratio of humic/fulvic acids (CHA/CFA) is lower (<1) compared to their uncultivated counterparts (~1). The alteration of the soil water regime also resulted in transformation of the individual compositions of amino acids. All studied types of Calcisols are characterized by changes in particle-size distribution of soils especially in the number of the silt fraction (0.01–0.05 mm) and the difference between uncultivated and irrigated soils, 10–20%, which is associated with the processes of colmatage by accumulation of a fine fraction and replacement of sub-fractions in the fraction of sand. The highest concentrations of nutrients are characteristic of the upper soil horizons (P up to 231, K up to 2350 mg/kg), which indicate their pedogenic and agrogenic origins rather than inheritance from the parent material. Soil P and K availability is rather high, with non-labile forms prevailing, although of near reserve. The surface irrigation results in apparent accumulation of water-soluble Mg2+ (1.6–2.1 meq/100 g) and K+ (0.6–0.9 meq/100 g), but the cation of Ca2+ predominates in the base cations’ composition, which is the most favorable in terms of soil agrogenic property formation. Data obtained will be useful for development of strategies for effective land use in arid, subtropical, overpopulated regions of Central Asia that have deficient water sources and intensive soil degradation.

Surveying the Distribution and Diversity of Predominant Mycobiota in Cultivated and Uncultivated Soils of Zaria, Northwestern Nigeria

Study’s Novelty/Excerpt This study presents a comprehensive survey of the distribution and diversity of soil fungi in cultivated and uncultivated soils of Zaria, Northwestern Nigeria, highlighting their morphological and microscopic characteristics, frequency, and relationship with physicochemical properties. It identifies and quantifies the presence of eight different fungal species, with Aspergillus niger being the most dominant, providing critical insights into the fungal biodiversity of this region. Additionally, the study correlates the richness of soil mycobiota with specific soil properties such as pH, organic matter content, and moisture levels, suggesting that these factors significantly influence fungal diversity and distribution, and recommending further research to assess their impact on soil productivity. Full Abstract Soil fungi are a crucial component of terrestrial ecosystems, playing a vital role as decomposers in nutrient cycles. The diversity of soil fungi serves as an indicator of soil health (favorable/deficient). Understanding soil biodiversity and its biological functioning will help not only in crop yields but also in a healthier society as it directly or indirectly enters the food chain. This study aimed at surveying the distribution and diversity of predominant mycobiota in cultivated and uncultivated soils of Zaria, Northwestern Nigeria. Focusing on their morphological and microscopic characteristics, percentage frequency, and relationship with physicochemical properties. After removing the surface soil, soil samples were randomly collected from two locations at 0-15 cm depths. Fungi were isolated via the dilution method on PDA. Previously established criteria were used to identify eight different fungal species: Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus, Fusarium spp., Mucor spp., Penicillium spp., Rhizopus spp., and Trichoderma spp. Aspergillus niger was the most dominant species, with a relative frequency of 26%, followed by Fusarium spp. and Rhizopus spp. With 18% and 17%, respectively. Aspergillus fumigatus was the least abundant (2%). The highest fungal isolation frequency (32%) was observed in L1 cultivated soil, closely followed by L2 uncultivated soil (31%), with the lowest in L2 uncultivated soil (16%). Physicochemical analysis indicated that these soils are rich in mycobiota, attributed to a basic pH range of 7.12-9.15, high organic matter content, and optimal moisture levels. Soils with significant organic matter due to litter accumulation, moist deciduous vegetation, and neutral to alkaline pH levels retain considerable moisture content, fostering a rich qualitative and quantitative mycobiota for recycling dead organic matter making nutrients available for suitable utilization. Further research is recommended to evaluate the impact of these isolated fungi on soil productivity, to determine whether their presence has a positive or negative effect.

Microbial Proxies for Anoxic Microsites Vary with Management and Partially Explain Soil Carbon Concentration.

Anoxic microsites are potentially important but unresolved contributors to soil organic carbon (C) storage. How anoxic microsites vary with soil management and the degree to which anoxic microsites contribute to soil C stabilization remain unknown. Sampling from four long-term agricultural experiments in the central United States, we examined how anoxic microsites varied with management (e.g., cultivation, tillage, and manure amendments) and whether anoxic microsites determine soil C concentration in surface (0-15 cm) soils. We used a novel approach to track anaerobe habitat space and, hence, anoxic microsites using DNA copies of anaerobic functional genes over a confined volume of soil. No-till practices inconsistently increased anoxic microsite extent compared to conventionally tilled soils, and within one site organic matter amendments increased anaerobe abundance in no-till soils. Across all long-term tillage trials, uncultivated soils had ∼2-4 times more copies of anaerobic functional genes than their cropland counterparts. Finally, anaerobe abundance was positively correlated to soil C concentration. Even when accounting for other soil C protection mechanisms, anaerobe abundance, our proxy for anoxic microsites, explained 41% of the variance and 5% of the unique variance in soil C concentration in cropland soils, making anoxic microsites the strongest management-responsive predictor of soil C concentration. Our results suggest that careful management of anoxic microsites may be a promising strategy to increase soil C storage within agricultural soils.

Comparative Study on the Bacterial Community of Cultivated and Uncultivated Rice Field Soils

A study was conducted to determine the changes in bacterial micro flora of soil in relation fallowing (abandonment) in rice fields. Soil samples from two paddy fields at Kumarakom region, southwest part of Kuttanad, Kerala, one field with paddy cultivation and the other fallowed, was subjected to the study. A total of 15 bacterial species, 8 from the cultivated field only, 6 from the fallowed field only and 1 common to both fields were isolated and identified in the study. The bacterial community in the soil of uncultivated field are entirely shifted from field where rice has been cultivated continuously. The persistent occurrence encountered in the cultivated field isolates were Bacillus megaterium, Pseudomonas aeroginosa and Klebsiella oxytoca while that in the abandoned field were of E coli followed by higher incidence of (80%) Enterobacter aerogenes and Citrobacter freundii. Under rice cultivation, soil pH, EC and bacterial density were generally higher than that in uncultivated soils while organic carbon in the soil was consistently lower than that in uncultivated soils. The study reveals the importance of bacteria in maintaining the health of a habitat and confirm that soil quality deteriorates over long-term fallowing.

Assessment of soil quality in irrigated arid lands under organic agriculture systems

The process of evaluating the soil quality is complex and is impacted by a variety of physical, chemical, and biological indicators as well as how they interact over time, particularly throughout different cultivation periods. The main objective of the current investigation is to examine how various organic farming practices affect the soil quality indicators at selected organic farms throughout various cultivation times. The study sites in Egypt were selected to represent two great soil groups (Torripsamments and Haplotorrerts). Moreover, the selected farms have different organic cultivation periods and management practices. Soil samples were collected from five different farms and uncultivated soil in each soil great soil group as control. After analyzing soil samples in the lab, physical, chemical, and biological indicators were assessed and used to calculate the Soil Quality Index (SOI). Principal Component Analysis (PCA) was used to obtain the minimum data set needed for soil quality evaluation. The length of organic cultivation in Torripasament raised the SQI value for physical and chemical indicators in the following order: 2 years > 6 years > 10 years > 13 years. Similar to Torripsament, the most sensitive indicators for SQI assessment in Haplotorrert were found to be soil respiration, microbial biomass C, microbial quotient, organic matter, and physical characteristics of soil quality. Results also indicated that organic farming improves most of the studied soil quality indicators of both soils (Torripsamment and Haplotorrerts). Soil respiration, Microbial Biomass (MBC), Microbial Quotient (MQ), organic matter, and physical aspects of soil quality were the most sensitive indicators of soil quality evaluation. Soil quality index (SQI) for Torripsamment was affected mostly by soil biological indicators, while soil physical indicators were the main indicators affecting SQI in Haplotorrerts. The best score for the soil quality index was at 13 years of organic cultivation periods in Torripsamment and at 17 years in Haplotorrerts.

Environmental pollution by heavy metals within the area influenced by the Tungurahua volcano eruption – Ecuador

Volcanic eruptions can have long-lasting negative effects on nearby environments and communities, especially those relying on agriculture. The Tungurahua and Sangay volcanoes in Ecuador’s highlands pose a significant risk to the region’s agricultural economy and inhabitants. The most recent eruption of the Tungurahua volcano spanned from September 1999 to March 2016. Volcanic ash is known to contain both non-essential and essential elements for plant growth, but excessive amounts of the latter can also be toxic and disrupt physiological processes. Additionally, the use of pesticides and fertilizers introduces additional elements to agricultural soils, which can potentially transfer to edible plants and raise health concerns for consumers. Despite this, little is known about the impact of the Tungurahua volcano’s latest eruption on soil deposition of micronutrient and heavy metals and their potential transfer to the food chain. To address this knowledge gap, we conducted a study to explore the impact of the Tungurahua volcano’s latest eruption on soil deposition of Cd, Cr, Ni, Pb, As, Fe, Cu, Mn, and Zn, as well as the physicochemical characteristics of cultivated and uncultivated soil samples and vegetables in the cantons most affected by volcanic ash. According to our findings, the physicochemical properties, micronutrient, and heavy metal concentrations of both cultivated and uncultivated soils differ and, in some cases, exceeded the maximum limits established, which could affect the health of the soil as well as of human beings through the trophic chain. This study provides valuable information for monitoring the chemical and physical properties of soil and vegetables in areas affected by the Tungurahua volcanic activity and agriculture, aiding in understanding their impact on the environment, agriculture, and potential health risks associated with locally grown crops in rural Ecuadorian communities.

Microbiological impacts of acid mine drainage on urban agriculture in Soweto, South Africa

The late 17th century discovery of gold in Johannesburg was accompanied by skewed income distribution in the world's most unequal society and more prosaic curses like acid mine drainage (AMD). This acid water contaminates ecosystems such as patches of urban agriculture that communities rely on to supplement income and nutritional needs. We investigated the extent to which AMD contaminates streams, irrigation water and subsequently, soil and vegetation on small-scale farms. We targeted microbial communities as the first line of biotic casualties in AMD infiltrated substrates. Sites were all in Soweto, Johannesburg, the first was just adjacent to a mine dump, the second was in a midstream section and the last was downstream where locals cultivate fields. We tested contamination of river sediment, river water, cultivated and uncultivated soil, borehole water used for irrigation and the crops themselves. The Biolog EcoPlate™ microbial community profiling kit was used, it measures the ability of microbes to use various carbon sources. The MicrotoxⓇ bio-assay was also used, it exploits a luminescent bacterium to indicate the level of biological toxicity in a medium. Both methods suggest severe contamination of environmental substrates close to the AMD source. The contamination attenuates downstream but was detected in soil, water and crops ~20 km away from the mine. Therefore, the impacts of mining are systemic in the catchment and authorities must appreciate the seriousness of the situation so that mitigation strategies can devised and implemented immediately.

Detection of post-harvest insecticide Flash 10% EC residues in wheat seeds and soil after its degradation by the UV-C

This study aimed to test the effect of the physical factor (UV-C) in degrading of insecticide Flash residue in wheat seeds and the soil post-harvest. As for the field experiments with regard to Flash residual in the soil, the results showed that the highest concentration of the insecticide was 3.10 ppm in the seeds produced from plants treated with Flash only, while the lowest concentration (below the detectable level) was in the wheat seeds from plants sprayed with UV-C treated Flash. As for the residual in the soil, the highest active compound concentration was 12.50 ppm appeared in the uncultivated soil treated with Flash untreated, compared to the lowest residual concentration (0.00) ppm was in soil planted with wheat plants treated with UV-C treated Flash. Findings also showed that the best exposure period to the UV-C was 20mn

Influence of landscape position and climatic seasonality on soil water and gas conductivity properties in agricultural soils

Agricultural landscape management and climate seasonality can influence soil structure, hydraulic conductivity, and air permeability within the context of soil water and soil gas mobility. To investigate this, in situ and laboratory-based data were collected from three agricultural landscape positions within a watershed in eastern Ontario, Canada during a growing season. Macropore classification, water infiltration tests, and air permeability measurements were conducted in situ and standard soil characterizations were carried out on soil samples. Hydraulic conductivity of the soil matrix, based on grain size data, indicated that the highest values were consistently measured in the B horizon at each landscape setting. Macropores were found to be more abundant within uncultivated drainage ditch bank soils, compared to the adjacent cropped fields. Macropores in the ditch bank soils were exclusively consisted of circular biopores, while both circular and linear macropores were observed in the cultivated field soils. Air permeability, vertical hydraulic conductivity, and horizontal hydraulic conductivity were also greater in the uncultivated soils, relative to the cultivated soils. Field saturated hydraulic conductivity measurements offered evidence of anisotropy, likely due to the vertical nature of the macropore features. Macropore disposition and extent varied over the growing season, especially in the cultivated field soils where tillage and field trafficking are physically disruptive. Seasonality of macropore development will influence temporal changes in advection-based mass exchange of gas and water in the vadose zone. Modeling of mass exchange in agricultural soils should consider time variability in macroporosity to more realistically characterize infiltration and soil gas emissions.

Physicochemical Properties of Long-term Rice-fallow Cultivation and Uncultivated Soils of Nalbari, Assam, India

We aimed to assess the changes in physical and chemical properties of soils due to long-term continuous cultivation of rice under a rice –fallow system and that was compared with adjacent uncultivated soils. Soil samples were collected from respective sites and some soil physical (bulk density; BD, water holding capacity; WHC, and moisture content; MC) and chemical properties (pH, electrical conductivity; EC, organic carbon; OC, available N, available P, available K, exchangeable Ca, exchangeable Mg, available S, available Zn and available B) analyzed were evaluated using descriptive statistics. The results indicated that the soils under cultivation with rice- fallow were significantly (P<0.05) higher in BD (1.40 Mg m-3) and lower in WHC (41.34%) than the adjacent uncultivated soils (BD=1.34 Mg m-3 & WHC=42.26%). Soil’s chemical properties were significantly (P<0.05) lower in cultivated rice-fallow soils than the uncultivated soils (pH=5.51 and 5.93, OC=0.63 and 0.89%, available N=245.56 and 418.37 kg ha-1, available P= 31.27 and 42.62 kg ha-1, available K=120.98 and 145.90 kg ha-1, exchangeable Ca=5.35 and 5.93 C mol (p+) kg-1, available S=53.42 and 61.14 kg ha-1, available Zn=0.31 and 0.39 mg kg-1 and available B=0.41 and 0.48 mg kg-1) respectively. Continuous cultivation of crops without adopting proper management practices leads to decline in soil physical and chemical properties and proper management practices have to be adopted to sustain the properties of soil and crop productivity.

Summer Rice–Winter Potato Rotation Suppresses Various Soil-Borne Plant Fungal Pathogens

Growing potatoes (Solanum tuberosum) using the idle rice fields in Southern China and the Indo-Gangetic Plains of India in the winter season through the rice–potato rotation (RC) system could support future food security. However, the modulation capacity of the RC system on soilborne fungal pathogens is still unclear. In the current study, a pot experiment was designed and conducted to monitor the dynamics of soil fungal community composition between the potato monoculture (CC) system and the RC system, where the two systems were set with the same soil conditions: autoclaving with fertilization; autoclaving without fertilization; autoclave-free with fertilization; and autoclave-free without fertilization. Then, the uncultivated soil (CK) and root-zone soil samples of conditions under the two systems were collected, and then soil physiochemical properties and enzymatic activities were determined. Next, the high-variable region (V5–V7) of fungal 18S rRNA genes of the samples were amplified and sequenced through the PCR technique and the Illumina Miseq platform, respectively. Finally, the fungal species diversity and composition, as well as the relative abundance of fungal pathogens annotated against the Fungiuld database in soil samples, were also investigated. The results showed that the RC could significantly (p < 0.05) increase soil fungal species diversity and decrease the relative abundance of soil fungal pathogens, where the RC could suppress 23 soil fungal pathogens through cultivating the rice during the summer season and 93.75% of the remaining pathogens through winter-season cultivation. Seven-eighths of the conditions under RC have lower pathogenic MGIDI indices (6.38 to 7.82) than those of the CC (7.62 to 9.63). Notably, both rice cultivation and winter planting reduced the abundance of the pathogenic strain ASV24 under the Colletotrichum genus. The bipartite fungal network between the pathogens and the non-pathogens showed that the pathogenic members could be restricted through co-occurring with the non-pathogenic species and planting crops in the winter season. Finally, the redundancy analysis (RDA) indicated that soil pH, electronic conductivity, available phosphorus content, and various enzyme activities (cellulase, urease, sucrase, acid phosphatase, catalase, polyphenol oxidase) could be the indicators of soil fungal pathogens. This experiment demonstrated that the rice–potato rotation system outperformed the potato monoculture on suppressing soilborne fungal pathogenic community.

Mineral Analysis and Percentages of Oxides (Hematite and Magnetite) in Two Cultivated and Uncultivated Soils in the Governorates of Al-Qadisiyah, Babylon and Najaf / Iraq

The aim of the research is to study the mineral analysis and oxides ratios in two cultivated and uncultivated soils in the governorates of Qadisiyah, Babylon and Najaf. And the determination of the proportions of hematite and magnetite oxide minerals, the following results showed that there is a great predominance of minerals (quartz and calcite) in all the soils of the middle Euphrates, and the proportions of the following minerals were diagnosed in Al-Qadisiyah Governorate, calcite 32.8%, which came in the first place for the uncultivated soils, while the cultivated soils prevailed Quartz mineral by 47.1%, while the province of Babylon showed the predominance of the mineral calcite at a greater rate than the rest of the minerals, by 33.6%, 30.8% for cultivated and uncultivated soils, respectively, while Najaf governorate recorded the highest prevalence of quartz mineral, which amounted to 38.1%, 34.8% for cultivated soils The oxide minerals (hematite and magnetite) recorded ratios of (2.0, 1.4, 1.0, 1.7, 0.9, 1. 1) The magnetite mineral reached (2.1, 2.5, 0.9, 2.7, 2.0, 1.0) for the governorates of (Al-Qadisiyah, Babylon, Najaf) for the cultivated and uncultivated soils, respectively.

Effect of Surface, Subsurface Drip Irrigation and Nanotechnology Perfusion Methods on Irrigation Efficiency and Saved Water Ratio in Plowed and Unplowed Soils

A field experiment was conducted in Al-Habbaniyah district / Al- Khalidiya district / Al-Anbar governorate, western Iraq, in Silty loam soil during the fall season 2020, to study the effect of surface and subsurface drip irrigation and perfusion irrigation with nanotechnology on irrigation efficiency, the amount of added water and the percentage of water saving in plowed and non-plowed soils. Perfusion was done when 50% of the prepared water was depleted. The treatments were distributed according to the Nested-Factorial Experiments Design (NFED) with three replications. The yellow corn, cultivar Euphrates, was planted on 2020/15/7. The American evaporation basin, type A, was used in the timing of irrigation. According to the rate of water consumption in terms of the equivalent depth of the added water, the total yield and the efficiency of water use. The results of the study showed the uniqueness of the drip irrigation system by giving the highest irrigation efficiency of 100% for the two plowing modes, while the surface drip irrigation system gave an irrigation efficiency of 83% in the uncultivated soil, and the lowest amount of water was added during the season, which amounted to 5215 m3. ha-1 in the nano-technology perfusion irrigation method with a savings rate of 29.97 and 13.19% compared with the surface drip irrigation method, while it reached 15.23 and 8% compared with the subsurface drip irrigation method in the plowed and non-plowed soils sequentially, the highest average total production was 11.7 tons of grain per hectare for the tillage and no-till treatment, and it decreased significantly to 7.5 tons ha-1 in the surface drip irrigation method, while the tillage treatments did not record significant differences in the short-term grain yield.

Types of vegetables shape composition, diversity, and co-occurrence networks of soil bacteria and fungi in karst areas of southwest China

BackgroundMicroorganisms are of significant importance in soil. Yet their association with specific vegetable types remains poorly comprehended. This study investigates the composition of bacterial and fungal communities in soil by employing high-throughput sequencing of 16 S rRNA genes and ITS rRNA genes while considering the cultivation of diverse vegetable varieties.ResultsThe findings indicate that the presence of cultivated vegetables influenced the bacterial and fungal communities leading to discernible alterations when compared to uncultivated soil. In particular, the soil of leafy vegetables (such as cabbage and kale) exhibited higher bacterial α-diversity than melon and fruit vegetable (such as cucumber and tomato), while fungal α-diversity showed an inverse pattern. The prevailing bacterial phyla in both leafy vegetable and melon and fruit vegetable soils were Proteobacteria, Acidobacteriota, Actinobacteriota, and Chloroflexi. In leafy vegetable soil, dominant fungal phyla included Ascomycota, Olpidiomycota, Mortierellomycota, and Basidiomycota whereas in melon and fruit vegetable soil. Ascomycota, Mortierellomycota, Basidiomycota, and Rozellomycota held prominence. Notably, the relative abundance of Ascomycota was lower in leafy vegetable soil compared to melon and fruit vegetable soil. Moreover, leafy vegetable soil exhibited a more complex and stable co-occurrence network in comparison to melon and fruit vegetable soil.ConclusionThe findings enhance our understanding of how cultivated soil bacteria and fungi respond to human disturbance, thereby providing a valuable theoretical basis for soil health in degraded karst areas of southwest China.

Distribution Characteristics of Heavy Metals in Different Particle Size Fractions of Chinese Paddy Soil Aggregates

In recent years, the migration and transformation of heavy metals (HMs) in soil has become a hot issue. Soil particle size has an important effect on the environmental behavior of HMs in soil. The distribution of HMs in soil is strongly affected by the size of a soil aggregate. In this study, paddy samples in both cultivated and uncultivated soils were collected from Anhui Province, China. The soils were sieved into six particle size fractions (diameters of >4000, 4000–2000, 2000–1000, 1000–250, 250–53, and <53 μm) and the wet digestion method was used to determine the concentrations of Cd, Cr, Pb, and As in the soil aggregates. The results showed that the surface soils were characterized by the largest proportion of coarsest aggregates of >4000 μm particles. Moreover, the concentrations of Cd, Cr, Pb, and As were elevated in cultivated paddy soils compared to uncultivated soils. The accumulation of HMs in all paddy soils increased with decreasing particle size. Although the smallest particle size fractions accounted for only 5.65–17.28%, they provided the highest distribution factor (DF) of Cr (1.35), As (1.25), Cd (1.28), and Pb (1.38). The highest contributions of HMs came from the coarser fractions (>2000 μm); however, for Cr, Pb, Cd, and As, the mass loading of <53 μm particles was up to 15.90%, 14.41%, 15.21%, and 15.70%, respectively. The highest content of HMs was found in the finest aggregate, with a pattern of decreasing with increasing aggregate size. In addition, the leachability behaviors of different HMs in different particle size aggregates were different. The leachability behaviors of Cr and Pb in the coarse particle size fractions were the highest, while the leachability behaviors of As and Cd in the less than 250 μm particle size fractions were 10–100 times higher than those of Cr and Pb. A correlation analysis showed that the particle distributions of Fe, TOC, and Mn had significant influences on the distributions of Pb, Cd, As, and Cr. This study provides a theoretical basis for the prevention, treatment, and remediation of HMs pollution in soil.

Impact of soil treatment with Nitrilo Triacetic Acid (NTA) on Cd fractionation and microbial biomass in cultivated and uncultivated calcareous soil.

The aim of this study was to evaluate the effectiveness of nitrilotriacetic acid (NTA) on cadmium (Cd) fractions and microbial biomass in a calcareous soil spiked with Cd under cultivated (Zeamays L.) and uncultivated regime subject to soil leaching condition. Expanding investigations related to soil-plant interactions on metal-contaminated soils with insights on microbial activity and associated soil toxicity perspective provides novel perspectives on using metal-chelating agents for soil remediation. The experimental factors were three levels of Cd contamination (0, 25, and 50mgkg-1 soil) and three levels of NTA (0, 15, and 30mmol L-1) in loamy soil under maize-cultured and non-cultured conditions. During the experiment, the adding NTA and leaching processes were performed three times. The results showed that the amount of leached Cd decreased in cultivated soil compared to uncultivated soil due to partial uptake of soluble Cd by plant roots and changes in Cd fractions in soil, so that Cd leached in Cd50NTA30 was 9.2 and 6.1mg L-1, respectively, in uncultivated and cultivated soils. Also, Cd leached in Cd25NTA30 was 5.7 and 3.1mg L-1 respectively, in uncultivated and cultivated soils. The best treatment in terms of chemical and microbial characteristics of the soil with the high percentage of Cd removed from the soil was Cd25NTA30 in cultivated soil. In Cd25NTA30 compared to Cd25NTA0 in cultivated soil, pH (0.25 unit), microbial biomass carbon (MBC, 65.0mgkg-1), and soil respiration (27.5mg C-CO2 kg-1 24h-1) decreased, while metabolic quotient (qCO2, 0.05) and dissolved organic carbon (DOC, 20.0mg L-1) increased. Moreover, the changes of Cd fractions in Cd25NTA30 in cultivated soil compared to uncultivated soil were as follows; the exchangeable Cd (F1, 0.27mgkg-1) and Fe/Mn-oxide-bounded Cd (F4, 0.15mgkg-1) fractions increased, in contrast, carbonate-Cd (F2, 2.67mgkg-1) and, organically bounded Cd (F3, 0.06mgkg-1) fractions decreased. NTA had no significant effect on the residual fraction (F5). The use of NTA, especially in calcareous soils, where most of the Cd is bound to calcium carbonate, was able to successfully convert insoluble fractions of Cd into soluble forms and increase the removal efficiency of Cd in the phytoremediation method. NTA is a non-toxic chelating agent to improve the accumulation of Cd in maize.