Major Soil Research Articles

Evaluation of Freeze–Thaw Erosion Intensity in the Ecological Function Reserve of the Greater Hinggan Mountains Based on Geographic Information Systems and a Geographic Detector

Freeze–thaw erosion is one of the three major soil erosions in China, including wind erosion and hydraulic erosion, which leads to the destruction of the natural environment, the imbalance of economic development, a threat to personal safety, and irreversible disaster to the country and people. China’s permafrost area accounts for about one-fifth of the country’s land area, and the seasonal permafrost area accounts for half of China’s land area, mainly concentrated in the Qinghai–Tibet Plateau, Xinjiang Province, Heilongjiang Province, Gansu Province, and other regions. In order to establish an evaluation system for the ecological function reserve of the Greater Hinggan Mountains, nine evaluation indicators were selected from the perspectives of topography, climate, soil, and vegetation conditions. GIS technology, a multiple collinearity test, and principal component analysis were used to comprehensively evaluate the freeze–thaw erosion in the ecological function reserve of the Greater Hinggan Mountains. This study categorized the evaluation results into five intensity levels, from micro to severe. Finally, the degree of influence of different influencing factors on freeze–thaw erosion and the interactions between the factors were analyzed using a geographic detector. The results showed the following: (1) The intensity of freeze–thaw erosion in the study area gradually increased from west to east, and the comprehensive evaluation results were −0.2552 to 0.7581. Overall, moderate, severe, and mild erosion accounted for 29.83%, 25.9%, and 21.54% of the total area of the freeze–thaw zone, respectively. (2) Soil moisture content and the annual range in temperature were the main factors contributing to freeze–thaw erosion. The degree of influence of the two effects on freeze–thaw erosion (q = 0.5997) was better than that of the single-factor effect.

Ecophysiological characterisation of a Klebsormidium strain isolated from a cave environment

Members of the genus Klebsormidium are ubiquitously distributed over the Earth and are among the major biological soil crust (BSC) forming microalgae. Their representatives can be found in terrestrial, aquatic, polar, desert regions and have been investigated so far from various aspects. However, the available information about Klebsormidium isolates from lamp-flora is very limited. In our work, we examined a Klebsormidium strain isolated from a Hungarian cave. The temperature optimum of its photosynthetic performance was tested by oxygen yield measurements and pulse-amplitude-modulated fluorescence, which were completed by determination of specific growth rates at different temperatures, from 10 to 40 °C. In addition, we also evaluated the brassinosteroid (BR) content of these cultures. Our results indicated that the studied microalga is capable of growing from 10 to 40 °C, with a 20–25 °C temperature optimum; these findings were in accordance with the observed hormone levels. Regarding photosynthetic performance, the oxygen yield and chlorophyll fluorescence measurements showed maxima at 30–40 °C and 35–40 °C, respectively. Moreover, the examined Klebsormidium strain demonstrates traits associated with cave adaptation, i.e., by high light utilisation factor (α) and diminished light adaptation parameter (Ik) values.

Efficacy of grape seed procyanidins for inhibiting denitrification varies by source, soil texture, and cropping history

Plant-derived denitrification inhibitors, such as procyanidins derived from grape seed extract (GSE), hold potential in mitigating nitrous oxide (N2O) emissions, a potent greenhouse gas and stratospheric ozone depleter. A deeper understanding of the effects of GSE – considering aspects like rate, source, application timing, storage, and interactions with soil properties and cropping histories – on denitrification inhibition remains elusive. We conducted a series of laboratory microcosm experiments to assess these effects using denitrification enzyme activity (DEA) and measurements of N2O and carbon dioxide (CO2) production rates under both anaerobic and aerobic conditions, soil inorganic nitrogen (N), and other major soil properties. Our results revealed that one commercial GSE brand (USP GSE) inhibited DEA, while another source was ineffective. Two non-procyanidin compounds in commercial GSE mixtures, tartaric acid and gallic acid, actually enhanced DEA. Inhibition efficiency of the USP GSE varied significantly across soils with differing crop histories and physical properties, exhibiting a positive dose-response in three out of the five soils examined. Greater efficiency was observed in sandy soils compared to silt loam soils and in soils with a history of continuous corn production as opposed to soybean. The GSE application timing relative to urea addition and a one-week room temperature storage had minor effects on denitrification inhibition. In corn-cultivated soil, co-application of GSE and urea reduced cumulative N2O production by 27 % compared to soils treated with urea alone. The CO2 production and nitrate levels remained largely unaffected by GSE application. These findings supported the potential of GSE as a soil amendment to reduce N2O emissions in corn-cultivated soils. However, challenges including purity of procyanidins, cost-effectiveness, and inconsistent performance under various systems warrant consideration for broader field applications.

Mercapto–palygorskite decreases the Cd uptake of wheat by changing Fe and Mn fraction in Cd contaminated alkaline soil

Wheat is one of the major sources of dietary nutrition for human body, and excessive Cadmium (Cd) in wheat poses a serious risk to human health. Mercapto–palygorskite (MP) has been proven to efficiently reduce Cd stress in wheat, but the contribution of major soil oxides to the stability of soil Cd under MP treatment is unclear. Here, a wheat pot experiment was conducted to evaluate the effects of soil Fe and Mn oxides on the Cd fraction under MP treatment. The results showed that the application of MP decreased the diethylenetriaminepentaacetic acid (DTPA)–extractable Cd by 24.0–34.7 %, increased the Fe and Mn oxide-bound Cd (OX–Cd) by 5.0–12.0 % and significantly reduced the Cd content in wheat grains (17.9–69.5 %). It also decreased the soil’s free Fe and Mn oxides by 6.1–11.7 %and 6.9–12.4 %, respectively, and increased the amorphous Fe and Mn oxides by 19.3–32.5 % and 21.9–24.1 %, respectively. In addition, the application of MP increased the concentration of Fe and Cd in soil colloid by 19.3–33.3 % and 11.3–45.3 %, respectively. Correlation analysis indicated that the amorphous Fe, Mn oxides in soil had a significant positive correlation with the content of Fe and Mn bound Cd in soil (P < 0.01). Primary component analysis (PCA) analysis shows colloidal Fe and Mn on the soil available Cd had relatively high positively loadings. Meanwhile, soil colloidal Fe exhibited a significant positive correlation with colloidal Cd (P < 0.01) and amorphous Fe oxides (P < 0.01). These results indicated that MP remediated Cd-contaminated soil by promoting an increase in amorphous Fe, Mn oxides and their adsorption and precipitation of Cd on these oxides.

Spatial variation in gully expansion rate in a loess-covered tableland region based on systematic sampling and high-resolution image interpretation

Soil erosion is a major soil degradation threat to land worldwide, and gully erosion is an important soil erosion process. The lack of research on the spatial variation in gully erosion has constrained planning for gully control at a large scale. In this study, high-resolution historical and present remote sensing images were used to investigate the areal gully growth rate (RA) with systematic sampling methods on loess-covered tablelands at a regional scale. Gully growth (not disturbed by human excavation or landfill) was identified in 74 of 98 sampling watersheds in the 10,000-km2 study area, and the average ratio of gully growth area to the gully area was 0.159 % (1969 ∼ 2021), with a coefficient of variation of 0.006. Moran's I index showed a significant spatial autocorrelation with RA in the study area. Runoff depth, drainage area, and soil bulk density were significantly correlated with RA in the sampling watersheds. GeogDetector revealed that the spatial variation in RA was significantly influenced by runoff depth, precipitation, soil bulk density at the regional scale. The spatial pattern of runoff depth had the largest effect on the spatial variation in RA when comparing the individual effect of each factor, while the precipitation and soil bulk density best explained the spatial patterns of areal gully growth at the regional scale. A random forest regression model performed well for simulating watershed RA, with R2 = 0.829. These results improve our understanding of the mechanisms of gully erosion in loess-covered regions.

Polyethylene microplastic can adsorb phosphate but is unlikely to limit its availability in soil

In plant growth experiments, the presence of microplastics (MPs) often reduces plant growth. We conducted laboratory experiments to investigate the potential of microplastics to adsorb the major soil nutrient phosphate; adsorption to MPs was then compared to adsorption to soil. Adsorption experiments used two contrasting soils, pristine high density polyethylene and artificially weathered material (the same material but exposed to 185 nm UV light for 420 h over 105 days), phosphate solutions (dissolved KH2PO4) ranging from 0.2 to 200 mg L−1 and a solid (g) to liquid (mL) ratio of 1: 150 at different values of pH (2–12) and different concentrations of background electrolyte (0.00–0.10 M NaNO3). The adsorption data were best fitted to linear and Freundlich isotherms. In initial experiments where pH was not fixed and with a background electrolyte of 0.10 M NaNO3, Kd values ranged from 3.37 to 27.65 L kg−1, log Kf from 1.21 to 1.96 and 1/n from 0.36 to 0.84. Exposure of the MP to 185 nm UV radiation led to the appearance of a C=O functional group in the MP; the partition coefficient Kd, calculated from the linear isotherm did not increase but the logKf value derived from fits to the Freundlich isotherm increased by a factor of 1.5. Kd values for soils were 3–7.5 times greater than those for MPs and log Kf values 1.1–1.7 greater. In the experiments in which initial pH and ionic strength were varied, adsorption was similar across all treatments with adsorption parameters for the higher organic content soil sometimes having the highest values and the pristine microplastic the lowest. In the desorption experiments most of the adsorbed phosphate desorbed. Overall our findings indicate that despite their ability to adsorb phosphate, MPs are unlikely to control the fate and behaviour of phosphate in soil.

Performance evaluation of Alccofine stabilised Marine clay as subgrade

Soil stabilization is a remedial measure that reduces permeability and compressibility, increases bearing capacity and shear strength of soil mass, which helps in reducing the settlement of structures. Marine clay is one of the major regional soil deposits in India, widely found in offshore and coastal areas. This is a type of low strength soft clay which majorly causes failure in pavements and foundation structures due to high settlements and low strength characteristics. The scope of this project is to improve the strength of marine clay by stabilizing it with alccofine. The work includes determination of index properties of marine clay by Hydrometer method, Atterberg’s test, Specific Gravity test, Free Swell test. The engineering properties of both virgin soil and soil stabilized with 3%, 6%, and 9% of alccofine are determined by various tests such as Standard Proctor test, California Bearing Ratio test. On the basis of CBR test, the optimum percentage of alccofine in marine clay is found out to be 6%.

Predicting runoff and sediment yields using soil and water assessment tool (SWAT) model in the Jemma Subbasin of Upper Blue Nile, Central Ethiopia

The Jemma Subbasin (JS) has a major soil erosion problem emanating from deforestation, overgrazing, and agricultural expansion, including farming of unproductive fringed lands and steep slope terrains. This study was conducted to assess runoff and estimate the subsequent sediment yields in the JS using the Soil and Water Assessment Tool (SWAT) model. The overall efficiency of the SWAT model to accurately estimate the sediment yields in the JS was evaluated by the values of its calibration (R2 = 0.66) and validation (R2 = 0.63), respectively. The findings of the SWAT model revealed that barren land was not only the most susceptible land use type to soil erosion, but also had the highest sediment loads followed by agricultural and grazing lands. In particular, the highest soil erosion coupled with significant sediment yields is attributed to the crop-growing period particularly in the months of July and August in which the cultivated lands were extremely vulnerable to soil erosion resulting from heavy rainfall. Consequently, sediment yields were all significantly greater in the agricultural fields of the lower, middle, and upper parts of the subbasin. This is because those agricultural lands were mainly composed of undulated and moderately steep slope terrains so that they had the highest soil erosion values. However, due to the dense vegetation cover and the associated root density, forestlands were the least erosion vulnerable land use type which in turn resulted in minimal soil loss. Furthermore, the SWAT model showed that the maximum upland sediment yield was estimated to be 3,685.14 tons/ha whereas the average upland annual sediment yield was predicted to be 78.1 tons/ha; however, the sediment yield can be doubled due to climate projection scenario. As a result of the effective implementation of cover (c) and conservation practice (p), the SWAT model predicted that the sediment yields can be reduced by 44.28 % and 35.92 % for RCP8.5 and RCP4.5, respectively. Effective designing and executing of proper soil and water management measures are crucial in the study subbasin so as to minimize the serious soil erosion challenges that can be accelerated by climate and land use land cover (LULC) changes for the long-term sustainability of the degraded landscape of the JS which is categorized by subsistence farming.

Unveiling the spatial differentiation drivers of major soil element behavior along traffic network accessibility

Advancements in transportation networks have induced a spatial-temporal convergence effect, accelerating socio-economic elements flow and dismantling the conventional "core-periphery" urbanization gradient. Accessibility of transportation networks emerges as a reliable indicator of urbanization. There has been a growing global and Chinese focus on the various forms of metal pollution in urban soil. This study aims to investigate the driving forces and effects of urbanization factors (Gross Domestic Product (GDP), value added of secondary industries (VA), night light (NL), population density (PD), and road density (Distance)), soil property factors (pH, electrical conductivity (EC), and total organic carbon (TOC)), and topographic factors (elevation (DEM), aspect, and slope) on toxic heavy metal elements (Cd, As, and Hg) and trace elements (Mn, Ti, V) in surface soil (0–20 cm) across varying accessibility levels in the Beijing-Tianjin-Hebei urban agglomeration. Results reveal significant influence of accessibility on Cd and Hg levels (p < 0.05), with higher accessibility areas displaying elevated element concentrations. According to the evaluation results of the single-factor pollution index, Cd and V have the highest pollution exceedance rates (93.18% and 75.76%, respectively). Moran's Index results highlight typical spatial clustering of elements, with hotspots in areas of high accessibility. Urbanization has led to distinct spatial agglomeration patterns in element concentrations and environmental factors. Geographic detector analysis reveal that in low accessibility areas, metal element pollution and distribution are influenced by a combination of complex factors, including soil properties (pH), terrain conditions (DEM), and the urbanization process (VA). In high accessibility areas, toxic heavy metal elements are primarily driven by urbanization factors, largely influenced by transportation activities, industrial development, and population density, while elements Mn, Ti, and V are still influenced by both natural processes and urbanization activities. These findings suggest that urbanization intensifies the impact on potential toxic elements in soil, and that trace elements are increasingly affected by urbanization, warranting further attention.

Relationships between Heavy Metal and Metalloid Contents and Major Soil Characteristics in Soils around the Former Kremikovtsi Metallurgical Plant Following Its Closure in 2009

Soils around the former metallurgical plant Kremikovtsi were subject of continued interest due to the environmental problems resulting from the plant's activities and especially heavy metal pollution. The aim of the present study was to investigate the contamination of the studied soils by metals and metalloids, several years after the closure of the plant (2009) and to relate their concentrations to basic soil parameters, pH, electrical conductivity, cation exchange capacity, clay content and total organic carbon, which will contribute to better assessment of their behaviour and remediation strategies. Total concentrations (aqua-regia) of the elements Al, B, Ba, Cd, Co, Cr, Cu, Fe, Li, Mn, Mo, Ni, Pb, Zn and As were determined. Elevated levels of the heavy metals Pb, Cd, Zn, and the metalloid arsenic (As) were found at the studied sites. Lead (Pb) exceeded maximum permissible concentrations (MPC), regulated by Bulgarian legislation for arable lands between 2 and 15 times, cadmium (Cd) between 3 and 5 times, arsenic (As) between 3 and 6 times, and zinc (Zn) was higher than MPC in three of the sampled sites. Soil pH values were in significant correlation with EC (R** = 0.805), CEC R** = 0.781), B (R* = 0.638), Cu (R* = 0.669), Fe (R** = 0.766) and Mn (R*** = 0.916) contents. Aluminium, cadmium, lithium and lead concentrations were related to the content of the clay fraction in soil. Positive correlation was obtained in multiple regression models between Pb, Al, Cd, TOC and soil pH, and negative relationship was observed with electrical conductivity (EC). The obtained results showed complex relationships between soil characteristics and the metals and metalloids, which emphasize the need for their simultaneous assessment, remediation and careful use for agricultural purposes.

Mechanisms of increased small nanoplastic particle retention in water-saturated sand media with montmorillonite and diatomite: Particle sizes, water components, and modelling

The processes by which small nanoplastics (NPs) accumulate in soil are unclear. To clarify the different deposition processes that affect small NPs (< 30 nm) compared to larger NPs in the soil environment, due to their interaction with clays as major soil components, the transport behavior of two-sized NPs (20 and 80 nm) with two clays (diatomite (Diat) and montmorillonite (Mont)) in NaCl and CaCl2 solutions were investigated in water-saturated quartz sand columns. The experimental results showed that more 20 nm NPs could enter the lattice structure of Diat than Mont in NaCl solution. This contributed to the stronger deposition of 20 nm NPs by Diat on sand, which was associated with a lower k1d/k1 value (obtained from two-site kinetic attachment model). In contrast, 80 nm NPs had a stronger reversible retention than 20 nm NPs with Mont, even though both sizes of NPs-Mont displayed a similar transportability. In CaCl2 solution, the larger NPs-Mont hetero-aggregates formed with a stronger suppressed depth of φmax based on Derjaguin-Landau-Verwey-Overbeek theory. Thus, Mont had a stronger transport inhibition than Diat for both NPs sizes, with a lower k1d/k1. These findings could benefit in predicting the size-based deposition of NPs in a heterogenous soil environment.

Synergistic Effects of N Fertilization and Irrigation on Soil Bacterial Community in Super Rice Paddies

Nitrogen reduction, in association with increased planting density and irrigation management, has been widely adopted in super rice cultivation systems to pursue higher yield with lower input. Here, soil microbial community structures under accurate N and water management were investigated after four years of experiments. Plot experiments were conducted with three treatments, including conventional farming practice (CF), reduced nitrogen with increased plant density (RNID), and reduced nitrogen with increased plant density and precise irrigation (RNIDPI). The results showed that RNID treatment increased soil bacterial diversity, enriched biomarker bacterial taxa, and altered bacterial community structure, with pH as the influential factor. The phylum Chloroflexi was enriched in the treatment of N reduction, while a higher ratio of Firmicutes was present in CF treatments. RNID treatment witnessed a low proportion of bacterial functional groups involved in nitrification and nitrate reduction. N fertilizer reduction with irrigation management increased rice yield (up to 22%) without changing the major soil fertility properties except for the increased pH and decreased ammonium N. The results suggest that N reduction, in association with increased plant density and accurate irrigation, is beneficial for super rice production.

Evaluation of Soil Organic Carbon Stability in Different Land Uses in Lithuania

The effective management of soil organic carbon (SOC) is highlighted as one of the strategies and cost-effective options for mitigating climate change, while soil nitrogen (N) often is specified as an essential element for plant growth. This study was conducted to evaluate basic soil physical, chemical, and microbial indicators in three major soil types dominated in Lithuania—Arenosols, Retisols, and Cambisols—under forest land, perennial grassland, and arable land. Furthermore, soil microbial biomass carbon (SMBC) and nitrogen (SMBN), their ratio, and soil microbial respiration (microbial CO2) next to SOC and total N were hypothesized to be important measures for assessing SOC stability under different land uses. Therefore, selected soil indicators were evaluated in the surface 0–10 and 10–20 cm mineral soil layers. The study results showed higher concentrations of SOC, N, SMBC, and SMBN, and soil microbial CO2 in forest land and perennial grasslands than in arable land. The higher SMBC/SOC and SNBN/TN ratios indicated a higher ability to accumulate SOC and N in forest land and grasslands. Higher SOC immobilization in forest land and higher N immobilization in arable land were both specified by the obtained SMBC:SMBN ratio. This study identified forest land followed by grassland as the best land management practice that addresses soil C sequestration through higher C immobilisation. Assessing soil in forest land as a control land use next to the agricultural land could be a reasonable soil management practice to evaluate C sequestration in the region. Additionally, it was assumed that evaluation of the SMBC and SMBN concentrations together with soil physical and chemical indicators allow for a more effective assessment of SOC stability. Taken together, these findings support recommendation to develop grassland (and especially forest land systems) through afforestation or within agroforestry system, without reducing the importance of the agricultural sector.

Modelling and prediction of major soil chemical properties with Random Forest: Machine learning as tool to understand soil-environment relationships in Antarctica

Digital Soil Mapping includes quantitative estimations of soil attributes in areas with little or no soil information, being important in remote landscapes such as the Antarctic ice-free areas. Our objective was to predict the spatial distribution of major soil chemical attributes in two important Antarctic Peninsula regions; as well as to identify the main environmental drivers of these attributes. For this, we compiled one of the largest soil databases of Antarctica and applied the machine learning algorithm Random Forest to predict seven soil chemical attributes. We also used covariates selection and partial dependence analysis to better understand the relationships of the attributes with the environmental covariates. Bases sum was the attribute which presented the highest prediction performance, whereas Na and P predictions presented the lowest. Both accuracy and uncertainty indicators showed the difficulties of Random Forest in handling natural outliers. The soil attributes distribution was related to the mean annual temperature and annual precipitation, multispectral bands and indexes related to the vegetation response, rookeries distance expressing the birds’ activity, and topographic attributes. The attributes showed a climatic gradient, with higher values of bases sum, pH, and Na in Northern Antarctic Peninsula, and higher total organic carbon, H + Al and P in Maritime Antarctic. This shows the climate covariates influence the soil variability in a macroscale, whereas terrain predictors control the soil at local scales. This study showed the Digital Soil Mapping potential to surpass the limitations of conventional mapping and indicated the feasibility in obtaining interpretable predictions which can be directly associated with the soil forming factors. Finally, the data generated can be used as reference to monitor the impacts of the climate changes on the soils of Antarctica.

Studies on the Available Nutrient-Supplying Capacity of Soil in Degradation Vulnerable Soils of Central Dry Zone in Tumkur District, Karnataka, India

Land degradation resulting from various natural and anthropogenic activities including the loss of organic matter, decline in soil fertility, erosion, acidity, alkalinity and the effect of toxic chemical is a serious global environmental problem, which may be triggered by climatic factors and their aberrations. The detailed reconnaissance soil survey was carried out in Tumkur district of Karnataka to study plant available nutrients in degradation vulnerable soils of central dry zone in Tumkur district, Karnataka during 2021-2022 using remote sensing, GIS and field studies. Satellite imageries (Sentinal -2) of three seasons were used along with soil map to delineate the degradation soils through visual interpretation. Using this map resource characterization was carried out. Out of thirteen soil pedons studied from Tumkur district, nine pedons were studied from central dry zone of Tumkur covering six taluks. These pedons belongs to Alfisols, Inceptisols and Entisols soil order. Soils were very strongly acidic (4.54) to very strongly alkaline (9.33) with non- saline nature in all pedons. The organic carbon content was low high, with higher content in Hosahalli of Madhugiri and decreased with increased depth in pedons. Available nitrogen was low to high and available phosphorus and potassium were low to medium in range. Secondary and micronutrients is soil was low to high, except zinc and boron, showing deficiency in most of the pedon. Soil fertility status assessment of different major soils of central dry zone of Tumkur help in developing sustainable management plan for improving the productivity and also growing the suitable crop, by preventing the degradation.

Spatial Analysis for the major element soil nutrients, and the effectiveness on Wheat and barley production in Ranya district

Spatial Analysis for the major element soil nutrients, and the effectiveness on Wheat and barley production in Ranya district

Global patterns and drivers of phosphorus fractions in natural soils

Abstract. Most phosphorus (P) in soils is unavailable for direct biological uptake, as it is locked within primary or secondary mineral particles, adsorbed to mineral surfaces, or immobilized inside of organic material. Deciphering the composition of different P forms in soil is critical for understanding P bioavailability and its underlying dynamics. However, widely used global estimates of different soil P forms are based on a dataset containing few measurements in which many regions or soil types are unrepresented. This poses a major source of uncertainty in assessments that rely on these estimates to quantify soil P constraints on biological activity controlling global food production and terrestrial carbon balance. To address this issue, we consolidated a database of six major soil P “forms” containing 1857 entries from globally distributed (semi-)natural soils and 11 related environmental variables. These six different forms of P (labile inorganic P (Pi), labile organic P (Po), moderately labile Pi, moderately labile Po, primary mineral P, and occluded P) were measured using a sequential P fractionation method. As they do not represent precise forms of specific discrete P compounds in the soil but rather resemble operational pools, we will now refer to them as P pools. In order to quantify the relative importance of 11 soil-forming variables in predicting soil P pool concentrations and then make further predictions at the global scale, we trained random forest regression models for each of the P pools and captured observed variation with R2 higher than 60 %. We identified total soil P concentration as the most important predictor of all soil P pool concentrations, except for primary mineral P concentration, which is primarily controlled by soil pH and only secondarily by total soil P concentration. When expressed in relative values (proportion of total P), the model showed that soil pH is generally the most important predictor for proportions of all soil P pools, alongside the prominent influences of soil organic carbon, total P concentration, soil depth, and biome. These results suggest that, while concentration values of P pools logically strongly depend on soil total P concentration, the relative values of the different pools are modulated by other soil properties and the environmental context. Using the trained random forest models, we predicted soil P pools' distributions in natural systems at a resolution of 0.5∘×0.5∘. Our global maps of different P pools in soils as well as the pools' underlying drivers can inform assessments of the role of natural P availability for ecosystem productivity, climate change mitigation, and the functioning of the Earth system.

Pedogenesis and Soil Resources Investigation of Major Soil Series of Ramanathapuram District, Tamil Nadu, India

Detailed soil survey (DSS) was carried out in drought prone district of Ramanathapuram during April 2023 to find out the weathering pattern of the soil. Totally 4 soil profiles was excavated from Mandabam, Pudukudi, Paramakudi and Muthukulathur areas and studied for soil morphological characteristics. Soil samples was collected in each horizon and analysed for soil physical characteristics, chemical constituents and weathering indices by using the standard procedures. The results showed that soil colour were ranged from dark yellowish brown to dark grey with single grain to angular to sub-angular blocky structure. Soil consistency ranged from loose, hard to very hard, firm to very firm, sticky to very sticky, plastic to very plastic in dry and moist condition. The bulk density, hydraulic conductivity, infiltration rate ranged from 1.19 to 1.31 Mg m-3, 0.01 to 8 cm hr-1 and 0.02 to 8 cm/hr. The variations in molar ratios and weathering intensity were seen in all the profiles. The weathering pattern of the soils from different areas of the coastal district was identified.

Soil saprophages as an emerging global source of micronutrients

Abstract ‘Hidden hunger’ occurs in humans and livestock and stems from deficiencies in microelements, essential amino acids, and vitamins. Triggered by insufficient intake of micronutrients in food and feed, even when macronutrients are abundant, hidden hunger can result in the development of serious diseases and pathological conditions. Finding sufficient micronutrients is often challenging because they are either obtained from limited external natural sources or synthesised de novo. Soil-dwelling saprophages comprise one of the largest proportions of zoomasses on Earth but remain surprisingly overlooked as a potential micronutrient source. To assess their nutritional content concerning micronutrients, we selected 31 invertebrate species obtained from natural ecosystems of European Russia or widely cultivated species originating mainly from tropical regions. They belong to major soil saprophage taxa: cockroaches (Blattodea), beetle (Coleoptera) larvae and imagoes, springtails (Collembola), millipedes (Diplopoda), fly (Diptera) larvae, earthworms (Haplotaxida), woodlice (Isopoda), crickets (Orthoptera). We assessed their proteinogenic amino acid, microelement, and vitamin composition. Taxonomic differences in the composition and ratio of micronutrients were determined and we identified specific taxa naturally enriched with micronutrients for future consideration as potential candidates for incorporation into food and feed supplements to alleviate hidden hunger in livestock and humans.

Distribution of nutrients and their indexing in major mango-supporting soils of different agro-climatic zones of Karnataka and its impact on yield

Knowledge of the spatial distribution of soil nutrients is essential for site-specific nutrient management, which forms an effective strategy in precision agriculture. As mango is one of southern Karnataka’s most important horticultural crops, the present study was conducted on 108 mango orchards under different agro-climatic zones to assess spatial nutrient variability for nutrient management. The soils of the study areas were acidic and non-saline. Nitrogen (N) deficiency was found in 84.26 percent area, whereas phosphorus (P) and potassium (K) contents were medium in most soils. Sulphur was sufficient, and calcium and magnesium contents varied with agro-climatic zones. The micronutrient (Zn, Fe, Mn) status was sufficient, except for copper and boron. The nutrient index for nitrogen was low, while phosphorus and potassium were low to medium. It is inferred that agro-management should include proper nitrogen fertilization, FYM, and boron throughout the growing cycle for better yield and quality.