To restore soils degraded by unsuitable practices, which have led to declines in organic matter content and associated consequences, sustainable land management (SLM) practices have been implemented in central Benin. This study aimed to evaluate the effects of these practices on soil organic matter (SOM) levels in cultivated soils in Central Benin. Soil samples were collected from a depth of 0 to 20 cm on SLM plots in two agricultural areas: N’Tchon and Odjobilè. The SLM practices studied were maize intercropped with pigeon pea (Cajanus cajan), mucuna (Mucuna pruriens), soybean (Glycine max), cowpea (Vigna unguiculata), groundnut (Arachis hypogea), aeschynomene (Aeschynomene histrix), and cassava (Manihot esculenta). For each SLM practice, adjacent control plots were sampled. Soil pH, cation exchange capacity (CEC), soil organic carbon (SOC), carbon organic stock (COS), and particulate organic carbon (POC) were measured. Compared to the adjacent control plots, the soybean–maize and aeschynomene–maize rotations significantly increased soil CEC (p<0.05). SOC differed significantly (p<0.05) among SLM practices, ranging from 0.37 to 1.67 g/kg. COS was higher with pigeon pea–maize intercropping (37.21 Mg C ha−1) in Odjobilè and with cassava–maize intercropping (37.46 Mg C ha−1) in N’Tchon. The contribution of coarse particulate organic carbon (cPOM-C) to total particulate organic carbon (tPOM-C) was smaller than that of fine particulate organic carbon. The greatest cPOM-C was observed with cowpea–maize and pigeon pea–maize intercropping. However, the greatest fPOM-C was observed with cowpea–maize intercropping in Odjobilè and with pigeon pea–maize intercropping in N’Tchon. Therefore, SLM practices, such as intercropping with pigeon peas and maize, can serve as an alternative to crop residue burning. These practices can help restore the fertility of degraded soils.
Avocado cultivation is a key agricultural practice in Wolaita, Southern Ethiopia, where smallholder farmers manage orchards of varying ages. Older orchards are often believed to have a more stable soil ecosystem due to the gradual buildup of organic matter, microbial communities, and nutrient cycling processes. However, their impact on soil–plant nutrient dynamics remains poorly studied. This study examines the influence of orchard age (5, 10, 15, 20, and 25 years) on soil fertility and plant nutrition across growth stages (preflowering, fruit setting, and postharvest). A total of 90 samples (45 soil and 45 leaf) were analyzed for macronutrients and micronutrients, alongside soil texture, bulk density (ρb), pH, organic carbon (OC), and cation exchange capacity (CEC). Additionally, orchard management practices and farmers’ estimated yields were surveyed to provide insights for improving soil fertility management. Orchard age did not significantly influence almost all of the measured soil fertility and leaf nutrients across growth stages. Yet, evaluation based on critical values indicated low levels of soil OC, total nitrogen (TN), phosphorus (P), magnesium (Mg), calcium (Ca), sulfur (S), and boron (B). Similarly, avocado leaf analysis revealed deficiencies in N, Ca, Mg, S, B, and copper (Cu) across different orchard ages and growth stages. Positive correlations between soil and leaf nutrient concentrations were observed for orchard age (N, P, K, Ca, Mg, S, B, and Zn) and tree stage (N, P, K, Ca, S, B, and Cu). Conversely, negative relationships were identified for Cu and Mg (age wise). Overall, uniformly inadequate soil fertility management could have resulted in lower fruit yield (55.41 kg/tree/year) compared to Ethiopia’s national average (92.24 kg/tree/year). These findings suggest that orchard age did not significantly influence soil fertility, thereby failing to meet the nutritional demands of avocado trees at various growth stages. To improve leaf nutrient concentration, enhanced soil management practices focusing on N, P, Ca, Mg, S, B, and Cu are recommended. Additionally, foliar applications of B- and Cu-based nutrients should be considered. Further research is necessary for a more comprehensive understanding of soil fertility dynamics in avocado production.
The rehabilitation of saline–alkaline soils in coastal regions has the potential to significantly enhance the ecological environment of these areas. This process not only increases agricultural productivity but also contributes to the economic advancement of coastal communities. A field experiment was conducted with different wood vinegar solution concentrations to investigate the impact of wood vinegar solution on soil using typical saline–alkali soil from Chongming Ecological Island. The research showed that the application of wood vinegar significantly ( p < 0.05) reduced the soil salinity (SS). The heavy alkaline soil with a high pH value of 9.39 was amended to achieve a pH value of 8.32. A 10%~20% wood vinegar solution significantly reduced 27.10%~28.30% of SS on the 25 th day ( p < 0.05). Moreover, the addition of wood vinegar solution increased soil nutrients, with the available phosphorus (AP) and the total nitrogen (TN) content increasing by 31.83% and 181.18%, respectively. These findings suggest that wood vinegar solution can reduce SS and improve fertility, and the best improvement can be achieved by proportioning the wood vinegar solution at the proper concentration. The beneficial effects of soil improvement on crop yields over extended time series require further investigation. Nevertheless, the findings support the potential of wood vinegar as a sustainable soil conditioner.
The study utilized simulated rainfall on medium (8%) and moderately steep (17%) slope gradients to evaluate the impact of different soil amendments on soil erosion. A controlled laboratory experiment was conducted using six soil boxes as experimental units, with treatments applied in a factorial arrangement of amendment type and slope gradient. Polyacrylamide (PAM), lime, and gypsum were added to the air-dried soil samples at rates of 40 kg·ha−1, 2 t·ha−1, and 4 t·ha−1, respectively. Simulated rainfall was used to investigate how different soil amendments (PAM, PAM + lime, PAM + gypsum, lime, and gypsum) affect infiltration, runoff, and soil loss compared to a control treatment at 8% and 17% slopes. Rainfall was applied at a constant intensity of 11 mm·h−1. Infiltration, surface runoff, and soil loss were monitored at 10-min intervals. Statistical analyses were conducted using analysis of variance. The findings indicated that soil amendments significantly influenced infiltration, runoff, and soil loss (p < 0.01), with treatment effects varying by slope gradient. Infiltration increased with the application of soil amendments, while runoff and soil loss decreased compared to control treatments at both slopes. Compared to the control, runoff was reduced by 23% (8% slope) and 25% (17% slope) for PAM; 20% (8% slope) and 21% (17% slope) for PAM + gypsum; 17% (8% slope) and 20% (17% slope) for gypsum; 10% (8% slope) and 16% (17% slope) for lime; and 21% (8% slope) and 22% (17% slope) for PAM + lime. In addition, total soil loss decreased by 50% and 53% for PAM, 45% and 49% for PAM + gypsum, 28% and 34% for gypsum, 22% and 25% for lime, and 49% and 51% for PAM + lime treatments at 8% and 17% slopes, respectively. These results demonstrate that polymer-based amendments, particularly PAM alone or in combination with lime or gypsum, enhance soil physical stability and reduce erosion under controlled rainfall conditions; however, the limited number of experimental units and laboratory setting warrant cautious interpretation. The use of PAM alone and in combination with lime or gypsum shows potential for improving soil physical stability, but further field validation and economic and environmental assessments are required before recommending widespread application for sustainable soil management.
Soil microbiota plays an important role in cycling and storage of essential nutrients for plant development. Studies about the interaction between wild pepper (chiltepin) and soil microbiota are scarce. Chiltepin (Capsicum annuum L. var. glabriusculum) is considered a progenitor of the cultivated chili peppers with a source of genetic traits for genetic improvement of the cultivated pepper. The aim of this study was to analyze the bacterial composition by identifying the plant growth-promoting rhizobacteria (PGPR) associated with wild and cultivated chiltepin plants, according to their location and season of the year. Wild pepper (chiltepin) habitat features contrasts throughout the year and could experience severe drought stress with high temperatures (dry season); despite this, the plant grows and yields fruits once the rain comes. These abiotic conditions make wild pepper and the associated microbiota an interesting system to study. Soil samples were collected during three seasons in 2017: dry, rainy, and post-rainy, in four municipalities of Sonora state. Analyses of pH, temperature, and inorganic nitrogen pool fluxes were performed. The soil pH associated with the cultivated chiltepin remained constant (≈9), whereas a decreasing trend was observed across all wild pepper growing locations as precipitation increased (≈6.0). In addition, the bacterial metabolic characterization was carried out from 14 selected bacterial strains that had activity in indole acetic acid production, phosphate solubilization, and siderophore production. The most predominant genus found belonged to Bacillus sp., followed by Serratia sp., according to the 16S rRNA gene sequencing. Finally, we identified 7 isolated strains that could be considered as potential bacteria to be used in bioremediation processes and a core microbial community as a promising source of native PGPR strains associated to wild pepper chiltepin that did not differ from the geographical area and season of the year.
Unsustainable land uses substantially alter soil properties, exacerbating soil acidification, threatening soil fertility, and impacting crop productivity globally, including in Ethiopia. Hence, assessing the impacts of various land use types (LUTs) on soil characteristics is imperative for the implementation of sustainable land management. A total of 60 soil samples were taken from two districts (Gorche and Hula) to evaluate the status of surface soil acidity across three LUTs: home garden agroforestry, Eucalyptus plantations (EPs), and fallow lands. Results indicated that the LUTs significantly (p < 0.05) influenced all measured soil properties. Soils under EPs were strongly acidic, consistently exhibiting higher exchangeable acidity (EA) and acid saturation (AS%). In addition, these LUTs had lower soil OC, total N, available P, and CEC contents. In contrast, home garden LUTs maintained higher pH, soil OC, total N, available P, CEC, and PBS while displaying lower EA and AS%, in comparison with EP and fallow LUTs. Fallow lands displayed moderately acidic conditions. The findings have implications for the importance of home garden agroforestry in restoring soil health for environmental and agricultural sustainability. Hence, the study suggests prioritizing these LUTs and replacing EP lands with native trees like bamboo, Hagenia abyssinica, Erythrina abyssinica, and others, which can enhance soil fertility. To improve soil fertility on fallow lands, the study advises implementing suitable soil and water conservation practices that can reduce soil erosion and increase the hydraulic conductivity of soils in these LUTs. In conclusion, these strategies may substantially help mitigate land degradation, restore productivity, and ensure long-term sustainability.
Heavy metal contamination of agricultural soils threatens food safety and human health through the transfer of toxic elements into edible crops. This study evaluated the concentration of selected heavy metals (As, Cd, Co, Cr, Ni, and Pb) in agricultural soils and commonly consumed vegetables cultivated in Al-Dejail District, Iraq, together with their associated environmental and human health risks. Soil and vegetable samples were collected from ten agricultural sites and analyzed using inductively coupled plasma–mass spectrometry (ICP–MS). The studied soils were characterized by neutral to slightly alkaline conditions (7.25–7.64), variable salinity (2.98–24.3 dS·m−1), low organic matter content (1.46%–1.76%), and sandy loam texture. The mean soil concentrations of Cr (193.2 μg·g−1) and Ni (152.0 μg·g−1) exceeded the permissible limits recommended by WHO/FAO, whereas As, Cd, Co, and Pb remained within acceptable levels. Cr and Ni exhibited the highest contamination factors (CF = 1.93 and 3.04, respectively), while the overall pollution load index (PLI = 0.49) indicated low overall soil pollution. In vegetable samples, As, Cd, and Co were not detected, whereas Pb exceeded the FAO/WHO permissible limit (0.3 μg·g−1) in all analyzed species. Cr concentrations ranged from 4.3 to 7.8 μg·g−1, with the highest accumulation observed in Solanum melongena, while Capsicum annuum exhibited the highest Pb concentration (9.8 μg·g−1). Human health risk assessment showed that hazard quotient (HQ), hazard index (HI), and carcinogenic risk (CR) values for Cr and Pb exceeded the recommended safety thresholds, indicating potential noncarcinogenic and carcinogenic health risks associated with long-term vegetable consumption. These findings identify Cr as the primary contaminant of concern in soils and Pb as the major contaminant in edible vegetables, emphasizing the need for continuous environmental monitoring and sustainable agricultural management to reduce heavy metal accumulation and protect public health.
Sediment deposition in the Vietnamese Mekong Delta (VMD) has declined sharply due to high-dike infrastructure and upstream damming, threatening long-term soil fertility and agroecosystem resilience. This study presents the first integrated assessment of sediment dynamics and soil health across four flood-based and conventional agricultural systems in VMD. We compared sediment accumulation and soil biochemical properties in (1) floating rice–fish farming, (2) lotus–fish farming, (3) natural flooding, and (4) triple-rice cropping systems. Sediment samples (n = 80) and soil samples (n = 35) were collected from 2022 to 2024. We applied principal component analysis (PCA) to identify a minimum data set of soil indicators and used a weighted soil health index (SHI) to evaluate system performance. Nonparametric Kruskal–Wallis tests revealed statistically significant differences in sediment mass, nutrient retention, and soil health among models (p<0.001). The lotus–fish and natural flooding models exhibited 8–15 times greater sediment deposition and SHI values that were 25%–33% higher than those of the triple-rice system, with strong correlations between sediment mass and soil health (R2=0.613). These models also enable reductions of up to 40% in postflood nitrogen and potassium fertilizer requirements. Using PCA and a weighted SHI framework, we highlight that flood-based systems, particularly lotus–fish farming, significantly enhance soil health and reduce fertilizer dependency. Our results support the scaling of sustainable agricultural transitions in line with Vietnam’s Resolution 120 on climate-resilient development in the VMD.
Tobacco cultivation in Bangladesh has expanded substantially over the past decade, particularly in Kushtia District. Although tobacco cultivation provides economic benefits, concerns remain regarding its effects on soil fertility and agricultural sustainability. This study evaluated the impacts of tobacco cultivation on soil fertility and farmers profitability in Mirpur Upazila, Kushtia District, integrating environmental and socioeconomic perspectives. Soil samples were collected from 20 tobacco-based (TB) and 20 non–tobacco-based (NTB) fields and analyzed for pH, EC, OM, and nutrients (N, P, K, S, Ca, and Mg). Soil fertility status was assessed using the Soil Nutrient Index. Socioeconomic data were collected from 50 farmers using structured questionnaires, while profitability was evaluated using a benefit–cost analysis and a Cobb–Douglas production function. TB soils exhibited significantly lower concentrations of N (0.06%), P (31.9 mg kg−1), S (17.8 mg kg−1), Ca (1.64 meq 100 g−1), and Mg (1.40 meq 100 g−1) than NTB soils. Notably, N and Ca concentrations were below their critical limits of 0.12% and 2.0 meq 100 g−1, respectively, indicating nutrient depletion associated with tobacco cultivation. Tobacco cultivation generated a net revenue of 50,661 BDT per acre and a benefit–cost ratio of 1.42. However, 74% of farmers depended on company loans, 70% reported health risks, and 72% perceived environmental pollution from leaf curing. Policies should support transitions to alternative crops, such as maize, mustard, wheat, pulses, and vegetables, by improving credit, extension services, and market access. However, the findings are based on a single upazila and should be validated through long-term, multilocation studies.
Assessing agricultural land potential is decisive for sustainable soil management, particularly in Rio Grande do Norte’s diversified farming systems. This study classified agricultural suitability in rural communities of Mossoró, RN, Brazil, identifying limiting factors and potentials for agroenvironmental planning. We conducted soil surveys analyzing climate, relief, vegetation, physicochemical properties, and pedological classification and then evaluated agricultural aptitude using the Land Agricultural Aptitude Assessment System. Seven soil classes were identified: Luvisols (5), Cambisols (4), Leptosol (2), Fluvisol (1), Acrisol (1), Plinthosol (1), and Vertisol (1). Luvisols, Acrisol, and three Cambisols (P7, P14, and P15) showed good agricultural suitability (Class 1aBC), despite water deficiency limitations. Other Cambisols (P5 and P6) ranged from good (1aBc) to regular suitability (2ab(c)), limited by shallow effective depth. Fluvisol (P3) and Vertisol (P13) presented regular suitability (2ab(c)), while Plinthosol (P12) had restricted suitability (class 3(a) (b) (c)) due to oxygen deficiency from plinthic horizons. Preservation areas (3(a) (b)) and agriculturally unsuitable lands (Leptosol P2) were identified, along with rocky Leptosol (P8) areas only suitable for natural grazing (Class 5N). Key limitations included water scarcity (climate-related), shallow soils (restricting mechanization), erosion susceptibility, and oxygen deficiency. The study demonstrates that aligning land use with identified suitability classes, combined with conservation practices, is essential to mitigate these constraints in semiarid ecosystems. These findings provide a framework for sustainable soil management in similar tropical dryland regions.
There is a need to increase barley, mainly limited by poor soil fertility associated with soil acidity. A field experiment was conducted in acidic soil of Sidama Highlands, southern Ethiopia, in 2019 to evaluate the performance of 10 barley genotypes with and without the application of chemical lime. The study also aimed at assessing lime application effects on soil chemical properties. The experiment was conducted in a split-plot design with three replications, where the lime (4.8; 0 t·ha−1) was assigned to the main plot, whereas barley genotypes were in the subplots. Results showed that the main effect of lime and genotype had significant (p≤0.001) effect on most phenology, growth and yield parameters of barley. However, their interaction had only a significant effect on growth parameters. Liming significantly reduced days to heading data (DH) and days to physiological maturity (DM) on average by 5 days and improved biomass and grain yields on average by 10%. In addition, genotype 208855b showed a significantly shorter number of days to emergence (DE), and genotypes 234911 and 27895a showed the shortest period regarding days to grain filling (DGF). Genotypes 217176b and 240478 showed the highest performance, whereas genotypes 215453b and 215454a showed the lowest performance in these parameters. Lime application significantly improved soil chemical properties by increasing soil pH, total nitrogen, available phosphorus, and cation exchange capacity (CEC), while reducing exchangeable acidity. The application of lime and/or the use of acidity-tolerant barley genotypes, particularly 217176b, in combination with recommended fertilizer rates, improved most measured traits and resulted in superior performance compared with the released barley variety HB-1307.
This study was conducted to evaluate the effects of liquid purple nonsulfur bacteria capable of solubilizing potassium from muscovite (MS-PNSB) on soil properties, potassium uptake, growth, and yield of hybrid maize under greenhouse conditions. A two-factor experiment was arranged in a completely randomized block design with 25 treatment combinations. Factor A consisted of five bacterial treatments (no bacteria, single strain M-Wa-19, M-Wa-24, and M-Wa-26, and a mixture of the three strains), and factor B consisted of K fertilizer application rates (0%, 25%, 50%, 75%, and 100% of the recommended rate). The results showed that MS-PNSB application improved soil pHH2O and reduced electrical conductivity (EC) and exchangeable Na by 4.74%–7.97%, 7.17%–27.5%, and 4.92%–18.5%, respectively. In addition, available soil nutrients increased, including NH4+-N (9.96%–33.8%), NO3--N (33.1%–42.8%), soluble P2O5 (28.8%–34.6%), and exchangeable K+ (41.4%–79.3%). Consequently, total K uptake by maize plants increased by 16.3%–51.4% compared with the noninoculated control. Reducing K fertilizer rates resulted in proportional decreases in total plant K uptake, following the order 100% > 75% > 50% > 25% > 0% K, corresponding to 1894.6, 1812.2, 1702.6, 1598.0, and 1426.6 mg pot−1, respectively. Moreover, inoculation with the MS-PNSB mixture significantly improved plant height (7.64%), ear length (5.78%), ear diameter (9.48%), and number of kernels per row (9.25%) compared with the noninoculated treatment. Application of single strains M-Wa-19 or M-Wa-26, or the three-strain mixture combined with reduced K fertilization, achieved yields comparable to the treatment receiving 100% chemical K fertilizer alone, indicating that sole application of chemical K fertilizer did not produce the highest yield and that MS-PNSB supplementation has strong potential to enhance maize productivity.
Understanding the physicochemical characteristics of the soil under major land-use types is important for efficiently utilizing soil resources and recommending promising management strategies. Therefore, this study was conducted to determine the effects of land-use types and soil depth on selected soil physicochemical properties in Ethiopia’s Derashe district, where intensive farming and deforestation have critically diminishes soil fertility. Eighteen composite soil samples were collected from cultivated, forest, and grassland use types at two soil depths (0–15 cm and 15–30 cm) with three replications. Two-way analysis of variance and Pearson correlation were used to analyze the data and were also further subjected to PCA and clustering using the statistical analysis software R. Clay and total nitrogen were significantly affected by land use, soil depth, and their interaction. Sand content, bulk density, porosity, pH, organic carbon, exchangeable calcium, and sodium varied with land use and soil depth. In contrast, available phosphorous (AP), exchangeable magnesium, potassium, cation exchange capacity, and base saturation differed only by land use. Silt content remains practically unaffected. Organic carbon was positively correlated with porosity (r = 0.7∗∗), total nitrogen (r = 0.97∗∗), and AP (r = 0.72∗∗) but negatively with bulk density (r = −0.7∗∗). The lowest mean values of most parameters were recorded at the cultivated land than forest and grassland, implying that the soil of the study area was exposed to intensive cultivation and high degradation, which requires immediate management intervention to restore the degraded soil properties and ensure sustainable soil productivity.
Crop-yield decline is a chronic problem for smallholder farmers in Ethiopia and much of sub-Saharan Africa. The main cause is the gradual depletion of soil nutrients when fields are continuously cultivated without adding sufficient external fertilizers. Most smallholders cannot afford inorganic fertilizers because they are costly and often unavailable at the right time. Although organic amendments such as farmyard manure (FYM) exist, farmers generally lack reliable guidance on how to use them effectively. To fill this knowledge gap, a 2-year field trial was carried out in four Ethiopian villages: Koga, Bachima, Geray, and Jiga (Jabi Tehnan and Mecha districts). The experiment used a randomized complete block design with three replications and tested 20 treatment combinations: five rates of a blended N-P-S-Zn-B fertilizer (NPSZnB) (100,150, 200,250, and 300 kg ha−1) crossed with four FYM levels (0, 12, 16, and 20 t ha−1). A blanket recommendation of DAP + urea served as a satellite control. Across the two cropping seasons, both grain and above-ground biomass yields responded significantly (p < 0.05) to the fertilizer, the manure, and their interaction. The highest biomass of maize (≈10,895.0 kg ha−1 at Jabi Tehnan and 10,787.9 kg ha−1 at Mecha) and grain yield (≈5524.6 kg ha−1 at Jabi Tehnan and 5487.652 kg ha−1 at Mecha) was obtained with the combined application of 250 kg ha−1 NPSZnB + 20 t ha−1 FYM. In contrast, the lowest yields occurred where only the blended fertilizer was applied (≈4600 kg ha−1). Equivalency calculations showed that to replace that inorganic blend entirely with FYM, farmers would need roughly 28 t ha−1 FYM for N, 6200 t ha−1 for P, 2030 t ha−1 for S, 25,000 t ha−1 for Zn, and 8350 t ha−1 for B, making the fertilizer indispensable.
Climate change is intensifying aridity and water scarcity in semiarid regions, placing increasing stress on soils, ecosystems and agricultural livelihoods. Sand dams are small structures built across ephemeral riverbeds, which have become a widely adopted adaptation measure, enhancing water availability and groundwater recharge. While their hydrological and socioeconomic benefits are well documented, their geomorphological effects remain poorly understood, despite the fact that erosion and sedimentation critically shape both soil stability and the long-term effectiveness of these dams. This study investigates whether sand dams induce measurable surface elevation changes in their surroundings, using a 10-year time series of Sentinel-1 data analysed with the Small Baseline Subset interferometry approach. A sand-dam-bearing river in Makueni County, Kenya, was compared with a nearby control river without such structures. The time series revealed ground elevation changes ranging from −12.3 to +11.2 cm between 2015 and 2025. The study river exhibited a more homogeneous distribution of elevation changes and fewer extreme fluctuations than the control river, suggesting that sand dams moderate erosive dynamics. In the vicinity of 14 of 19 dams, positive elevation changes were detected, which are interpreted as localised sediment deposition. Particularly in mid-course cascades, stabilising effects were evident, whereas some upper and lower course dams showed less consistent patterns, reflecting site-specific differences in slope, soil type and sediment supply. The results indicate that sand dams act not only as water harvesting structures but also as sediment traps that contribute to soil stabilisation. However, the reliance on radar interferometry highlights methodological limitations, as erosive and depositional processes may cause signal decorrelation, and the absence of ground validation constrains direct interpretation. Future research should therefore integrate radar time-series analysis with field-based sediment and groundwater monitoring to better capture the coupled hydrological and geomorphological effects of sand dams.
Freshwater scarcity driven by population growth, industrialization, and urbanization has increased the use of wastewater as a source of irrigation, leading to the accumulation of heavy metals (HMs) in soils. However, studies in Ethiopia remain focused on individual HM concentrations and lack an integrated evaluation of overall pollution levels. The data from 39 peer-reviewed studies published between 2012 and 2025, covering ten HMs (Cd, Pb, Cr, Ni, Zn, Cu, Co, Mn, As, and Hg), were synthesized to assess both concentrations and pollution levels of HMs in wastewater-irrigated urban soils in Ethiopia using pollution indices and multivariate statistical analyses, including principal component analysis (PCA) and cluster analysis (CA). The mean concentrations (mg kg−1) of Cd (7.46), Mn (979.78), and Hg (2.63) exceeded FAO/WHO limits, while those of other HMs remained within permissible limits. The mean contamination factor (CF) values for Cd (24.9) and Hg (6.57) showed very high contamination, while the mean geo-accumulation index (Igeo) values for Cd (2.01) and Hg (5.38) were classified as strong and extreme pollution, respectively. The mean values of ecological risk factor (Eri) for Cd (747.26) and Hg (262.87) revealed serious and high ecological risk, respectively. Similarly, the mean values for contamination degree (Cdeg) = 40.54 and modified contamination degree (mCdeg) = 4.05 showed high contamination. The mean values of potential ecological risk index (PERI), 1047.44, and pollution load index (PLI), 1.14, are classified as significantly high ecological risk and intermediate contamination, respectively. The results of PCA explained 69.53% of the total variance and identified three components, while CA grouped HMs into three clusters (As–Hg, Ni–Co and Mn–Zn–Cu–Cd–Pb–Cr). Strong correlations were observed for As–Hg (0.77), Cu–Zn (0.71), and Cr–Ni (0.59). Overall, Cd and Hg are the dominant contributors to both pollution levels and ecological risk, indicating environmental and health risks and the need for control measures involving policymakers, researchers, and farming communities.
Changes in plant cover have a positive or negative effect on soil organic carbon (SOC) sequestration in the lakeside wetlands. We examined SOC and its fractions at three single-dominant plant communities, including Phragmites australis, Juncus effusus and Juncellus serotinus in lakeside wetland of Caohai Lake, Guizhou Province, China. SOC, particulate organic carbon (POC), mineral-associated organic carbon (MAOC), and microbial residue carbon (MRC) were concentrated in surface soils. The ratio of MAOC/SOC was apparently higher than that of POC/SOC, whereas fungal MRC contributed more substantially to SOC than bacterial MRC. Phragmites australis exhibited a greater value of SOC, POC, MAOC, iron-bound organic carbon, and fungal MRC but the lowest ratios of MAOC/SOC, fungal MRC/SOC, and total MRC/SOC. The establishment and expansion of P. australis enhanced both the concentration and instability of SOC in lakeside wetland of Caohai Lake. The fungal MRC was regulated by amorphous iron oxides and complex iron oxides, while SOC and MNC had significantly positive impacts on amorphous iron-bound organic carbon and complex iron-bound organic carbon. The role of mineral preservation and fungal microbial necromass production in SOC sequestration and stabilization in Caohai Lake depended on vegetation species.
Soil erosion is among the most pressing environmental challenges in Ethiopia, exerting profound impacts on economic development, food security, and ecosystem services. This study aims to quantify soil loss rates and identify erosion hotspot areas within the Gotta watershed to support effective soil and water conservation measures. The revised universal soil loss equation (RUSLE) was applied to estimate annual soil loss, while a GIS-based multicriteria decision analysis (MCDA) was employed to delineate areas at high erosion risk. Key erosion-controlling factors were generated using GIS tools to enhance spatial analysis. The results from the RUSLE model revealed mean annual soil loss rates of 6.82, 9.41, and 11.49 tons per hectare per year for 1996, 2008, and 2020, respectively. Although most of the watershed exhibited low to moderate erosion risk, 2.6% of the area was classified as high to very severe, with annual soil loss exceeding 15 tons per hectare. The MCDA analysis further indicated that approximately 5.5% of the watershed qualifies as erosion hotspot zones, characterized by a composite erosion index greater than 2.6. Both approaches consistently highlighted the southern and northern portions of the watershed as particularly vulnerable to severe erosion. In addition, gully erosion was found to affect 749.6 ha (3.93%) of the watershed, with sampled gullies showing an increasing spatiotemporal expansion of erosion tracks. These findings provide critical insights for policymakers and watershed managers, enabling the prioritization of targeted soil conservation interventions and the promotion of sustainable land management strategies.
Solid-liquid partition coefficient (Kd) and soil-to-plant transfer factor (TF) are two important parameters in numerical models for predicting radionuclide availability in plants. They have implications for agricultural strategies in high-background radiation areas, where the activity concentrations of naturally occurring radionuclides (NORs) are significantly elevated. This study measured the Kd and TF values of U-238, Ra-226, and Po-210 for various soil types, and the linkages between Kd, TF, and soil properties were analyzed. The objective of the study is to reveal a fact that applying a TF that does not actually provide real information on plant uptake, given that it takes into account the entirety of the soil in which the plant grows. The results show that U-238, Ra-226, and Po-210 contribute a significant fraction to gross alpha in both soil and plant samples. The average Kd values of the radionuclides are in the order of [Kd of Po-210 (Kd(Po)) (1351 L kg(-1)) < Kd of Ra-226 (Kd(Ra)) (2506 L kg(-1)) < Kd of U-238 (Kd(U)) (3977 L kg(-1))]. The average TF values of the radionuclides are in the order of [TF of gross alpha (TFalpha) (0.081)] < [TF of Ra-226 (TFRa) (0.169)] < [TF of Po-210 (TFPo) (0.173)] < [TF of U-238 (TFU) (0.192)]. The positive correlation of Kd-OM and the negative correlation of TF-OM indicate that OM strongly absorbs radionuclides in the soil and reduces their transfer to plants. These findings provide vital empirical parameters for refining predictive environmental models, which assume TF is a constant transfer. A correlation between Kd, TF, and OM content in soil has significant implications for agricultural strategy. It suggests that radionuclide activity concentrations in plants could be reduced by the application of OM.
Semiarid regions are predominantly vulnerable to climate fluctuations and change, which can contribute to higher CO2 emissions. Therefore, there is a need for sustainable farming practices that mitigate climate change as the demand for food and feed production increases. This study systematically reviewed existing literature on the impact of conservation agriculture on carbon dioxide (CO2) fluxes in semiarid regions. Subsequently, a systematic search that adhered to Preferred Reporting Items for Systematic Reviews and Meta-Analyses on two search engines (i.e., Scopus and Web of Science) produced 1312 articles, of which 31 relevant studies met the inclusion criteria of this study. The results highlighted that conservation agriculture increases soil organic carbon in semiarid regions, which further reduces the emission of CO2. It was shown that the frequently used instrument to measure CO2 fluxes is the static chamber due to its simplicity and cost-effectiveness. Several studies reported that incorporating legumes into crop rotation systems enhanced carbon sequestration and subsequently reduced the emission of carbon. Moreover, it has been noted that the type of crop rotation, residue management and tillage practice used in a particular system could influence the reduction of CO2 emissions. However, it was recommended that there is a need for long-term studies on the impact of conservation agriculture in order to understand its positive impact on CO2 fluxes and climate change mitigation. Further research is needed on the long-term impact of conservation agriculture on CO2 emissions.
