Composite Soil Samples Research Articles

Soil health implications of some d-block metals in selected agricultural soils in Southeast Nigeria.

Soil fertility, soil health and environmental management through the estimation of background concentration of potentially toxic elements is required for environmental safety. This study aims at investigating the concentration, fertility and potential health risks of some d-block metals (Ti, V, Fe, Mn, and Mo) in some agricultural soils, and establishes the relationship between the metals and some soil properties. Eight elevation ranges resulted from the digital elevation models of the study area; two in Ishibori (NG1, NG2), three each in Agoi-Ibami (CG1, CG2, CG3) and Mfamosing (SG1, SG2 and SG3). One soil profile pit was sunk along each of the elevations. Thirty-five composite soil samples were collected at 0-30, 30-60, 60-90, 90-120, 120-150, 150-180 and 180-200cm depending on soil depth. Only the profile means of Mn (660.82 ± 612.89mg/kg) and Mo (2.61 ± 0.73mg/kg) exceeded permissible concentrations and would pose threats to the environment. Also, the concentrations of the d-block metals exceeded permissible values in Ishibori making them prone to toxicity. The metals were irregularly distributed with depth; however, Mn and Fe were concentrated in the subsurface soils. Clay and sand contents correlated positively and negatively, respectively with all the d-block metals at p < 0.05. The linear model was more efficient in estimating V and Mo via soil properties with adjusted R2 of 33 - 67% for the metals. In conclusion, agricultural activities and geology may influence the accumulation of d-block metals, hence the call for environmental monitoring to curtail metals' assimilation by crops. HIGHLIGHTS: • Mn and Mo threaten the environment the most. • Soils in the Southern Guinea Savannah are most prone to d-block metals contamination. • BD, pH, Mg, and CEC are the best predictors of d-block metals in the soils. • The linear model was best performing in the estimation of V and Mo, respectively.

Meso-scale deformation and strength mobilization mechanisms of EPS composite soil

Expanded polystyrene (EPS) composite soil is composed of two solid constituents (cemented soil and EPS beads), which together with the inter-constituent interfaces form a unique mesoscopic structure. The macroscopic behavior of EPS composite soil has been widely investigated so far, but the focus has seldom been put on the meso-scale mechanisms behind the macroscopic deformation features and strength mobilization processes. In this study, systematic experiments and refined numerical simulations are utilized to examine the meso-scale mechanical responses of EPS composite soil under triaxial compression to reveal the associated mechanisms. Here, meso-scale is a scale smaller than a sample scale but larger than an EPS bead scale. First, the mechanical behavior of cemented soil, EPS material and their interface is obtained in experiments; their constitutive models are formulated, and the model parameters are calibrated based on experimental results. Then, experiments and refined numerical simulations of triaxial compression on EPS composite soil are performed. It is found that the rich macroscopic mechanical behavior of EPS composite soil has a mechanical source (contrast in mechanical behavior between EPS and cemented soil) and a geometric source (non-uniform distribution of EPS beads). The mechanical source leads to highly non-uniform stress and strain distributions within an EPS composite soil. The geometric source causes strain localization in zones with local concentration of EPS beads, leading to three macroscopic deformation modes, i.e., overall shear localization, local lateral expansion, and overall uniform expansion. In strength mobilization, cemented soil matrix first mobilizes its strength because it takes most of the load and contributes much to deformation at the early stage of triaxial compression. EPS beads are later progressively involved in the overall load bearing and deformation of the EPS composite soil sample. EPS beads make more contribution to stress than to strain due to its soft nature.

Comparative analysis of effects of climate-smart agriculture practices and conventional agriculture on selected soil physicochemical properties in Nyimba district, Zambia

Background. Many smallholder farmers in the developing world live in adverse poverty and rely on agriculture as their primary source of income and household food. In Zambia, agriculture production is the main activity for people in rural areas of the country. The study evaluated the effects of climate-smart practices: Gliricidia sepium alley cropping, conservation agriculture basin, ripping, and conventional agriculture cropland on selected physicochemical properties of soil among smallholder farmers’ croplands in Nyimba district, Zambia. Materials and Methods. Cropland under conservation agriculture basin, ripping, agroforestry gliricidia alleyed cropping, and conventional agriculture cropland hosting the practices for more than five years were considered for soil sample collection. Thirty (30) composite soil samples were collected: gliricidia alley cropping (n = 6), conservation agriculture ripping (n = 6), basin (n = 6), conventional agriculture one (n = 6), and conventional agriculture two (n = 6) following a zigzag pattern on soil surface depth of 0–30 cm. The collected composite soil samples were analyzed at the University of Zambia Soil Science Laboratory. Soil laboratory results were analyzed with Minitab Statistical Software version 17 for mean squares, standard deviations, and Tukey’s LSD. Results and Discussion. The study revealed significant effects (p &lt;0.05) of gliricidia alley cropping, conservation agriculture ripping, and basin on soil bulk density, porosity, power of hydrogen (pH), cation exchange capacity, available phosphorus, total nitrogen, exchangeable bases sodium, calcium, and potassium. Exchangeable base magnesium was recorded as insignificant across the considered practices off-course with minimal mean variations with conventional agriculture cropland. Conclusion. The study shows that implementing climate-smart agriculture practices has the potential to improve crop productivity per hectare through reclaiming and amending depleted soil physicochemical properties in a mid and long run. This also indicates the importance of climate-smart agricultural practices implementation among smallholder farmers’ cropping fields.

Green trees preservation: A sustainable source of valuable mushrooms for Ethiopian local communities.

In Ethiopia, Pinus radiata and Pinus patula are extensively cultivated. Both plantations frequently serve as habitats for edible fungi, providing economic and ecological importance. Our study aims were: (i) to investigate how plantation age and tree species influence the variety of edible fungi and sporocarps production; (ii) to determine edaphic factors contributing to variations in sporocarps composition; and (iii) to establish a relationship between the most influencing edaphic factors and the production of valuable edible mushrooms for both plantation types. Sporocarps were collected weekly from permanent plots (100 m2) established in 5-, 14-, and 28-year-old stands of both species in 2020. From each plot, composite soil samples were also collected to determine explanatory edaphic variables for sporocarps production and composition. A total of 24 edible species, comprising 21 saprophytic and three ectomycorrhizal ones were identified. Agaricus campestroides, Morchella sp., Suillus luteus, Lepista sordida, and Tylopilus niger were found in both plantations. Sporocarp yields showed significant variation, with the highest mean production in 28-year-old stands of both Pinus stands. Differences in sporocarps variety were also observed between the two plantations, influenced by factors such as pH, nitrogen, phosphorus, potassium, and cation exchange capacity. Bovista dermoxantha, Coprinellus domesticus, and A. campestroides made contributions to the variety. The linear regression models indicated that the abundance of specific fungi was significantly predicted by organic matter. This insight into the nutrient requirements of various fungal species can inform for a better plantation management to produce both wood and non-wood forest products. Additionally, higher sporocarps production in older stands suggests that retaining patches of mature trees after the final cut can enhance fungal habitat, promoting diversity and yield. Thus, implementing this approach could provide supplementary income opportunities from mushroom sales and enhance the economic outputs of plantations, while mature trees could serve as a source of fungal inoculum for new plantations.

Bacterial Density in Soil Samples Collected from Hospital Wastes Dumping Site at Chukwuemeka Odumegwu Ojukwu Medical Centre, Uli, Anambra State, Nigeria.

The soil quality is characterized by adequate nutrients as a result of abundant nutrients cycling bacteria. Most soil in Nigeria has been subjected to different kinds of pollutants resulting from anthropogenic activities which have become a major threatening factor to the quality of soil. This study was carried out to evaluate bacterial density in soil samples collected from hospital wastes dumping site at Chukwuemeka Odumegwu Ojukwu Medical Centre, Uli, Anambra State. A total of 30 composite soil samples were aseptically collected from the site using a sterile soil auger. The samples were analyzed for total heterotrophic bacterial count (THBC) and phosphate solubilizing bacterial count (PSBC) using standard plate technique. The predominant bacterial isolates that aided nutrients cycling were appropriately characterized, and their densities in both impacted and non-impacted soil samples were enumerated. Also, the bacterial isolates were characterized based on morphology, microscopy, and biochemical characteristics. There was an increase in the THBC and PSBC in the impacted soil, and Gram negative rods such as Pseudomonas, Klebsiella, and Micrococcus species (Gram positive) were the bacterial isolates. The study has revealed that wastes generated from hospital enhances microbial proliferation in the soil, which invariably increases soil fertility. Keywords: Bacterial Density, Soil Samples, Hospital Wastes and Dumping Site

Bacterial Diversity and Occurrences in Cassava Effluent-Contaminated Soil Collected From Ozubulu, Anambra State, Nigeria

Environmental degradation due to indiscriminate disposal of refuse has a tremendous effect on microbial activities in the soil. Most soil in Nigeria has been subjected to different kinds of pollutants resulting from anthropogenic activities which have become a major threatening factor to the quality of soil. This study was undertaken to evaluate bacterial diversity and occurrences in cassava effluent contaminated soil from Ozubulu, Anambra State. A total of 30 composite soil samples were aseptically collected from cassava effluent disposal site using a sterile soil auger. The predominant bacterial isolates that aided nutrients cycling were appropriately characterized, and their diversities in both impacted and non-impacted soil samples were enumerated. Furthermore, the bacterial isolates were characterized based on morphology, microscopy, and biochemical characteristics. There was a significant reduction in the occurrences of the bacterial isolates in the impacted soil, and Gram negative rods such as Pseudomonas, Klebsiella and Micrococcus (Gram positive) species were the bacterial isolates. The study has revealed that cassava effluent affects microbial distribution in the soil. Keywords: Bacterial, Diversity, Occurrences, Cassava, Effluent-Contaminated and Soil

Assessing the impacts of soil and water conservation practices on soil physicochemical properties in contrasting slope landscapes of Southern Ethiopia

In Ethiopia in general and in the study area, soil erosion, which is the main cause of land degradation, is a significant environmental and agricultural problem. The efficiency of various land management strategies used over time to reduce their detrimental effects on soil quality and health has been questioned. The purpose of this study was to determine the efficacy of soil and water management methods applied to the Offa District of the Wolaita Zone in southern Ethiopia. A total of 36 composite and core soil samples were taken from the topographies of both conserved and non-conserved fields from the top 20 cm soil depth. The collected soil data were examined using analysis of variance (ANOVA), and the mean values of the treatments were separated using the Fisher multiple range test. The results revealed that the physical and chemical properties of soil (pH, Organic carbon, Total nitrogen, Available phosphorus, Cation exchange capacity (CEC), exchangeable basic cations (Ca2+, Mg2+, K+, and Na+), Soil texture, and Bulk density showed a significance difference (p < 0.05) between the measures of soil and water conservation (SWC). The treated soils of Fanya juu, stone bund, and soil bund had the highest soil pH (6.56, 6.56, and 6.11), organic carbon (1.80, 1.62, and 1.76 %), total nitrogen (0.18, 0.16, and 0.17 %), accessible phosphorus (2.72, 2.77, and 1.94 ppm), and all exchangeable basic cations showed higher amount than untreated. The results showed that the implemented SWC structures had high value in restoring and preserving soil nutrients and improving the productive capacity of the soil. This study confirmed the effectiveness of SWC practices in improving soil quality. To achieve soil quality, it's essential to maintain awareness and use of the latest technology. It is strongly advised to highlight the urgent need for SWC training, public awareness, and government support.

Exclosure effects on soil physicochemical properties and woody species diversity in the south Rift valley basin of Ethiopia

Establishing exclosures has become common rehabilitation and restoration of degraded lands in Ethiopia. This study examined the effects of exclosure on identified soil physical and chemical properties, and woody diversity at the Wamole sub-watershed. Representative soil samples were taken from the open grazing land and eight-year-old exclosure. Six transects and 18 plots, with an area of 20 m × 20 m and containing nine from each open grazing ground and nine from the exclosure, were constructed alongside to sample the vegetation. From every plot, by ‘X’ design, composite soil samples were collected for investigation of total nitrogen (TN), available phosphorus, cation exchange capacity (CEC), soil pH and soil organic carbon content (SOC), and the bulk density (BD) of the soil, 18 undisturbed soil samples were taken from 0 to 20 cm deep. 34 and 28 woody species belonging to 25 and 20 families were registered between exclosure and adjacent open grazing land respectively. Significantly (P < 0.05) higher Index Shannon-Wiener (3.36) in the exclosure indicated better species diversity in the exclosure than in the open grazing land (3.13). Soil properties such as available phosphorus, pH, OC, TN, and CEC showed significant differences (p < 0.05) across different land uses. Exclosures facilitated to reclaim of degraded lands by re-establishing vegetation and improving soil nutrient status in a comparatively short period. It suggests that further research on socio-economic aspects of exclosures has to bring livelihood improvement in the locality to establish additional degraded open grazing lands in the research sub-watershed.

Validating SoilDoc kit for site‐specific fertilizer recommendations for maize production in Tanzania

AbstractSoilDoc is a soil testing kit designed to determine site‐specific fertility status and enhance the accessibility of soil test services for smallholder farmers in the tropics. This study aimed to validate the use of the kit in the Southern Highlands (Mbeya and Njombe) and the Eastern Zone (Mvomero) of Tanzania. Composite soil samples collected from 144 smallholder farm fields were analyzed using 0.01 M CaCl2 extraction solution as per SoilDoc protocols. Out of 144 sites, 24 sites were randomly selected for nutrient response trials. The treatments were (i) absolute control, (ii) N alone, (iii) P Low N (Recommended P and half of recommended N), (iv) recommended NP, (v) NPK, (vi) NPS, (vii) NKS, and (viii) NPKS, replicated three times. Maize yields were subjected to analysis of variance. Relative yield for each nutrient applied was subjected to Cate and Nelson procedure to determine critical ranges. Across all sites, the control yielded least (0.55–5.20 Mg ha−1). Application of NPS, NPK, NP, or NPKS produced the highest yield (2.5–6.9 Mg ha−1). The SoilDoc critical ranges were 0.30–0.48 mg P kg−1; 0.15–0.27 cmolc K kg−1, and 4.1–4.8 mg S kg−1. Mbeya and Njombe soils appeared deficient in either NS, NP, NPK, or NPK, while in Mvomero 53% of soils were deficient in N alone and 31% of soils were deficient in NS. In the absence of field‐specific soil tests, applying N, P, S, and K in Mbeya and Njombe and N and S in Mvomero would be best bets for maximizing yield and return on fertilizer investment.

Distribution and Characterization of Sulphur fractions in Entisols, Inceptisols and Alfisols Soil Orders of India

The present investigation was conducted to distribute and characterization of different Sulphur (S) fractions in selected soil orders of India. Soil samples were collected from cultivated fields in different states of India, covering West Bengal, Jharkhand, Bihar, Uttar Pradesh, Uttarakhand, and Himachal Pradesh. These states belong to the soil orders Entisols, Inceptisols, and Alfisols. A total of two hundred seventy composite soil samples were collected from ten locations of each order, representing three depths: 0-15 cm, 15-30 cm, and 30-45 cm, with thrice replication. After analyzing the various sulfur fractions, the results showed that there was no distinct distribution of sulfur reported in the various locations. In Entisols soil order, non-sulphate sulfur contributes highest fraction with a mean of 2744.99 mg kg-1 while lowest contribution was found in available sulfur with a mean of 25.24 mg kg-1 of total S followed by organic sulfur (112.54 mg kg-1), adsorbed sulfur (97.79 mg kg-1). A similar pattern was observed in Inceptisols and Alfisols soil orders. Available S was positive and significantly correlated with organic Sulphur in Entisol and Inceptisol while negative correlated with remaining fraction of S. Based on the sulfur availability index, the dominant fraction of sulfur in all three soil orders was non-sulfate sulfur.

Soil Chemical Attributes under Agrosilvopastoral Systems and Pasture

Agrosilvopastoral systems involve the consortium of trees, agricultural crops, and pasture, in the same area, concomitant or sequential, based on agroecological bases and on the cycling of organic matter and nutrients. This research compares soil fertility under pasture and agrosilvopastoral system. The area of 5 ha, is located on the Campus of the Federal University of Viçosa in Florestal city, central region of Minas Gerais state, formed by Urochloa decumbens for about 30 years, in an argisolic dystrophic Red Yellow Latosol. Two agrosilvopastoral systems - in single lines 2 x 10 m and double lines 2 x 2 + 10 m - were compared with pasture without trees. The soil preparation was conventional, with ploughing and leveling grids, in December 2009. Seedlings of the hybrid Eucalyptpus urophylla and E. grandis, clone GG100, were planted in level and subsoiler lines, which received 500 kg ha-1 of reactive phosphate at a depth of 0.5 m. At planting, each seedling received 120 g of N:P:K 10:28:06 + 0.3% B + 0.5% Zn; and 120 g of N:P:K 20:00:20, at 60 days. The corn was sown in the alleys, receiving 360 kg ha-1 of N:P:K 08:28:16 + 0.5% Zn, at planting, and 240 kg of urea ha-1, at 30 days. After the corn harvest, the pasture was formed naturally from the seed bank. At 135 months post-planting, five composite soil samples were collected in each studied area, obtained from ten simple samples of the 0-5 cm layer. The following attributes were analyzed: pH, P, K, Ca, Mg, Al, H + Al, OM, and Prem. The results were submitted to analysis of variance and F test (p,0.05), and the means of the significant treatments were compared by the Scott Knott test (p&lt;0.05). Both APS provided an increase in the levels of OM, P, Ca, SB, t, and H + Al in the soil, keeping unchanged the other attributes analyzed in relation to conventional pasture. No significant differences in fertility were detected between the two agrosilvopastoral systems studied.

Roots are the key for soil C restoration: A comparison of land management in the semiarid Argentinean Pampa

The objective of the study was to elucidate the relationship between soil management and carbon (C) stocks, and to identify the factors that intervene in the processes that favor C sequestration. The study was carried out on a farm in the Argentinean semiarid pampas with four land management practices (2019–2021): natural grassland (NG), crop-pasture rotation (RO), soybean monoculture (S-S) and with cover crop (S-CC). Aerial and root biomass were quantified at cover crop termination and soybean flowering. In addition, residues on soil surface were determined two times a year. In all cases, C and N contents were quantified. On composite soil samples, soil organic C (SOC), particulate C (POC), microbial biomass C and N (MBC, MBN), and soluble C and N were determined at 0–0.1 m depth. Results showed that NG had the highest and the most stable aboveground (3807.1 kg residue-C ha-1) and belowground inputs between years (4965.8 kg root-C ha-1). Similar results were observed in RO treatment during the first year (4221.0 kg root-C ha-1) diminishing by 67% after plowing for the annual crop in the second year reaching similar root-C values than S-CC and S-S (721.7 kg ha-1). S-S presented the lowest aboveground (49%) and belowground inputs (77%) compared to NG. Cover crops (S-CC) contributed with 31% and 14% of extra residue-C and root-C, respectively, compared to S-S. MBC showed a non-linear response with increases in root-C, reaching maximum carrying capacity of 110.6 ± 4.3 kg MBC ha-1 with root-C inputs ≥ 2200 kg ha-1. Our results showed significant relationships between root-C and POC and SOC, while no relationships were found for aboveground residues. Increases in soluble N explained 86% of SOC variability. Both RO and S-CC reached the “4 per Mille” goal with an average annual SOC storage rate (ΔC) of 0.24 and 0.16 Mg ha-1 y-1, respectively, while S-S had SOC losses of 0.04 Mg ha-1yr-1.

Assessing the potential of forest stands for edible mushrooms productivity as a subsistence ecosystem service in Ethiopia

Wild edible mushrooms are recognized as a fundamental component of forest management and rural development initiatives, offering farmers a substantial supplementary source of income. Thus, exploring the valuable wild mushrooms and modeling fungal fruiting in different forest systems in the tropics could provide additional insight into fungal responses to environmental factors and allow for better decision making related to forest management in the face of climate change. In many parts of the world, edible wild mushrooms are considered economically valuable non-timber forest products (NTFPs). In Ethiopia, forest management policies based on NTFPs are needed to make better use of these resources. A thorough assessment of wild mushroom as NTFPs that occur in Ethiopian forests and their uses is key to understanding what actions are needed to manage forests at the local level. We aimed (1) to record the fresh weight of edible wild mushrooms produced in natural and plantation forests in Ethiopia and (2) to develop models to predict sporocarp production in these two forest systems. We established 63 sample plots of 100 m2. All mature and young edible wild mushrooms were harvested weekly during the main rainy season to quantify their abundance and fresh weight. Composite soil samples collected from each plot and climate data recorded for each study area were used to develop models. In total, 64 edible fungal species were collected. The average annual total fresh weight production in plantations (2097.57 kg ha–1) was significantly greater than that produced in natural forests (731.18 kg ha–1). Six alternative models were fitted, and three yield categories were also defined as possible responses. Latitude, soil organic matter and minimum daily temperature were identified as relevant explanatory factors. Our yield classification models were fitted to predict the annual yields of edible fungi based on climate, soil and area-specific information in Ethiopia. The developed models should serve as a basis for further studies in Ethiopian forests to optimize forest management based on NTFPs, specifically edible wild mushrooms.

Factors associated with foodborne pathogens and indicator organisms in agricultural soils

Soil can be a route for contamination of fresh fruits and vegetables. While growers routinely manage soil nutrient levels, little research exists on the synergistic or antagonistic effects of soil nutrients on foodborne pathogens. Data on foodborne pathogen prevalence in unamended soils is also relatively limited in literature. This study evaluated foodborne pathogen prevalence (Salmonella, Listeria monocytogenes) and concentration of indicator bacteria (total coliforms, generic Escherichia coli) in agricultural soils, and characterized associations between soil properties (e.g., macro- and micro-nutrient levels) and each microbial target. Three Virginia produce farms, representing different regions and soil types, were sampled four times over 1 year (October 2021–November 2022). For each individual farm visit, composite soil samples were collected from 20 sample sites (25 m2) per farm per visit for microbial and nutrient analysis (n = 240). Samples (25 g) were processed for Listeria spp. and Salmonella using a modified FDA BAM method; samples (5 g) were enumerated for generic E. coli and total coliforms (TC) using Petrifilm. Presumptive Listeria spp. and Salmonella isolates were confirmed by PCR using the sigB and invA genes, respectively. Soil nutrients from each sample were tested and evaluated for their association with each microbial target by Bayesian Mixed Models. Salmonella prevalence was 4.2% (10/240), with 90% (9/10) recovered on Farm C. Listeria spp. and L. monocytogenes prevalence were 10% (24/240) and 2.5% (6/240), respectively. When samples were positive for generic E. coli (107/240), the average concentration was 1.53 ± 0.77 log10 CFU/g. Soil pH was positively associated with L. monocytogenes [Odds Ratio (OR) = 5.5] and generic E. coli (OR = 4.9) prevalence. There was no association between Salmonella prevalence and any evaluated factor; however, Salmonella was 11.6 times more likely to be detected on Farm C, compared to other farms. Results show pathogen prevalence was relatively low in unamended soils, and that factors influencing prevalence and concentration varied by microbial target and farm.

Evaluate the use of Mehlich-III compared to Mehlich-I as a soil test in Northeast Florida

Soil laboratories throughout the United States have widely integrated the Mehlich-III (M-III), derived from Mehlich-I (M-I), methodologies to extract soil nutrients. However, there have been concerns regarding its precision. The University of Florida's Hastings Agricultural and Extension Center (HAEC) conducted a soil sampling during the spring of 2021. This research aimed to rigorously compare the extraction efficiencies of M-I and M-III, specifically focusing on critical soil nutrients like phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), boron (B), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn). From forty-six meticulously chosen fields, 276 composite soil samples derived from two distinct depth strata (0–15 ​cm and 15–50 ​cm) were analyzed using both methods. Our findings highlighted the superior extraction prowess of M-III, which showcased an efficiency almost threefold compared to M-I. Intriguingly, the correlation between M-I and M-III extraction efficiencies weakened with escalating soil nutrient concentrations. The coefficient of determination (r2) between M-I and M-III had a high correlation value and was statistically significant (p<0.05) for all macro- and micronutrients. We found that the correlation between M-I and M-III became more robust with an increase in sample size and a higher correlation coefficient. It is noteworthy to mention that the M-III method has the propensity to provide slightly inflated soil nutrient estimations. Since soil labs worldwide use M-III equations derived from M-I, this study proposes that soil labs reinvestigate and possibly adopt new correlation equations to estimate soil nutrients using M-III.

Diffuse Reflectance Spectroscopy for Mapping Soil Carbon Stock in the Gilbués Desertification Region at Brazilian Cerrado

The carbon stock (C Stock) is a key soil attribute, especially in areas under degradation. The objective of this study was to map the C Stock and other physical and chemical attributes on the soil surface of a micro-watershed located in the Gilbués Desertification Nucleus and to calibrate pedometric functions to map them, applying spectra obtained by Diffuse Reflectance Spectroscopy (DRS) in the near-infrared (NIR) region. This study was developed in the Piripiri Stream Micro-watershed (PSMW), which presents different levels of degradation. A total of 214 composite soil samples were collected from the 0–0.10 m depth layer. Spectral and laboratory analyses were performed following traditional methods. The results from 100 samples were subjected to descriptive analysis, pedometric modeling, and geostatistics, while the remainder were used exclusively for the prediction and modeling of the predicted attribute maps. C Stock ranged from 0.3 to 11%, with the highest values associated with the least sandy sites. We assert that stakeholders, including government agencies, could utilize DRS for mapping main soil attributes, such as C Stocks, soil granulometry, or total organic carbon, in regions characterized by similar parent material and soil properties. This application can support informed decision-making regarding land management in extensive areas facing soil threats.

Effects of Soil and Water Conservation Practices and Slope Gradient on Selected Soil Physicochemical Properties in Ejersa Watershed, Toke Kutaye District, Ethiopia

This study was conducted to assess the effects of soil and water conservation practices and slope gradients on selected physicochemical properties of soil at Ejersa Watershed based on a total of 18 composite soil samples collected and analyzed using standard laboratory procedures. The values of pH, electrical conductivity, cation exchangeable capacity, organic carbon, organic matter, total nitrogen, and available phosphorus determined in soil samples collected from conserved and nonconserved plots were 6.4 and 6.16, 40.26 mS/m and 15.12 mS/m, 33.51 meq/100 g and 21.56 meq/100 g, 2.66% and 2.24%, 4.58% and 3.86%, 0.24% and 0.15%, and 29.45 ppm and 17.68 ppm, respectively. Soil pH, electrical conductivity, moisture, total nitrogen, and available phosphorus were significantly different ( p &lt; 0.01 ) between treated and untreated plots and among the slope classes. Values of soil organic carbon and organic matter showed significant differences ( p &lt; 0.05 ) between land types but not among the slope classes. Soil cation exchange capacity showed significant difference ( p &lt; 0.05 ) between land types as well as among the slope classes. Relatively, higher values of many of the physicochemical parameters were recorded in samples collected from the treated land and lower slopes which might be attributed to the deposition effects of the conservation practices and decline in the rate of soil erosion.

Human-induced land use changes and phosphorus limitation affect soil microbial biomass and ecosystem stoichiometry.

Soil and microbial biomass carbon (C), nitrogen (N), and phosphorus (P) play an important role in soil nutrient dynamics in biogeochemical cycles of terrestrial ecosystems. However, increased human activities as a result of agricultural intensification on soil nutrients and microbial C:N:P stoichiometry are poorly understood in this fragile forest-savanna transition agroecosystem. This study aimed to (i) assess soil and microbial C, N, and P stoichiometry in different land use systems, and (ii) examine the effect of soil and microbial C, N, and P stoichiometry on soils susceptible to human-induced land use changes. A total of 82 composite soil samples at a depth of 0-20 cm were sampled from forest, savanna, grassland, fallow and cropland for laboratory analysis. The results revealed that the concentrations of C, N, and P were low in Fallow and Cropland compared to other land use systems. Analysis of variance in microbial C, N, and P stoichiometric ratios revealed a significant decreasing tendency compared to soil C:N, C:P and N:P ratios with no statistical significance (p < 0.05). The C:P and N:P ratios were low compared to the C:N ratio in land uses. A significant positive correlation was observed between MBC and MBN (0.95; p < 0.01), and with C and N (0.69; p < 0.01). There were significant interactive effects of land use on soil and microbial variables. The estimated microbial C:N:P stoichiometric ratios (21:2:1) were well constrained in the study area. The transition from Forest to Cropland resulted in 64%, 52%, and 71% reduction in C, N, and P, respectively. This implies that phosphorus is the main factor limiting productivity. The low availability of phosphorus in these tropical soils may have resulted in low C:P and N:P ratios. Therefore, we conclude that our results highlight the importance of phosphorus limitation on ratios of microbial C:P and N:P in landuse systems. Nutrient inputs such as fertilizers, manure and crop residues should be applied to croplands to improve soil and microbial C, N and P levels. Further, effects of land use on soil nutrient status and stoichiometry at 1-meter depth will be considered in our future work.

Assessment of natural radioactivity and associated radiological risks from soils of Hakim Gara quarry sites in Ethiopia

One of the ways of minimizing radiation risks to workers and the public is assessing potential sites that are suspected of producing radiation. Among such locations, quarry sites stand out because areas of granite and other rocks, especially those of uranium family potentially have high concentrations of radiation. This study was aimed to assess one such quarry sites (Hakim Gara site), located near Harar town, Harari region-Ethiopia. To assess the radiological impact of natural radioactivity of quarry activities in the study area, activity concentrations of natural radionuclides 238U, 232Th, 226Ra and 40K in the soil samples were investigated by collecting twenty composite soil samples from different sites of the area. Measurements were carried out using high purity germanium (HPGe) Gamma Spectrometry detecting system for acquisition of data and making analysis using Genie 2000 software. From the result, mean Activity concentration of 238U, 232Th and 40K obtained were 51.9 ± 15 Bq/kg, 68.32 ± 9.75 Bq/kg and 220.0 ± 2.0 Bq/kg, respectively. Average Activity concentration of the 226Ra was 32.71 ± 2.02 Bq/kg. These values were used to calculate and estimate the radiological risks due to environmental radiation exposure contributed from the quarrying activities. The average external and internal hazard indices were 0.45 ± 0.09 mSv/y and 0.49 ± 0.23 mSv/y both of which were below the permissible limit of unity. The results obtained for 238U and 232Th were higher and significant from the world average which need further regulatory monitoring. The level of 40K was below the world average. Hence, this research provided a foundation for future studies on subsequent investigations and to aid realistic regulatory and policy decisions.

Using date palm (Phoenix dactylifera L.) as bio-monitors of environmental quality for exposure assessment and pollution source tracking

The entry of potentially toxic elements (PTEs) into the environment has been raised as a problem for various countries. So, this study aimed to investigate the PTEs concentration in the environment. In this cross-sectional study, Ahvaz city, the capital city of Khuzestan province, was divided into 5 areas. At each site, three-date palms were selected. Leaves and mesh fibers samples were collected from the young palm (3 years) with a maximum trunk height of 3–4 m. Plant leaves samples were separated from the middle section of the main leaves area of the plant and mesh fibers were selected from the different parts of the palm data trunk (top, middle, and bottom of the palm data trunk on all four sides of the palm). Then, data palm samples were divided into two groups of washed/unwashed. Soil samples were collected from the closest point to the palms date at a depth of 0–50 cm including at two depths (0–20 cm and 20–40 cm), and then combined to make a composite soil sample. After the preparation of samples, PTEs were measured by ICP-OES. The highest PTEs concentrations were found in industrial and high-traffic sites and the lowest was obtained at the control site. The largest bioconcentration factor (BCF) was related to copper (2.34–7.49) in mesh fibers samples and in the leaves (1.65) in the control area. Principal component analysis (PCA) results showed metal(loid)s (copper, nickel, zinc, lead, iron, arsenic, and cobalt) are mostly related to brake wear and tire of vehicles and asphalt and road dust, while the metals (Manganese, chromium, and cadmium) mostly originate from industrial sources. Palm leaves, mesh fibers, and soil can be used as a cheap biomonitoring factor for PTEs analysis, especially in industrial and high-traffic regions.