Effective Cation Exchange Capacity Research Articles

Cover crop management systems improves soil quality and mitigate water erosion in tropical olive orchards

The production of olive trees in shallow soils in hillslopes requires adequate soil and water conservation systems. In this context, soil use and management besides vegetation cover contributes to better soil quality and the sustainability of the olive cultivation system. Thus, the objective was to determine the physical and chemical properties that are indicative of soil quality in areas of Dystrudepts, under different soil cover management systems in olive cultivation in tropical region. Olive tree culture field experiment was established in 2015, where soil was sampled over three years (2016, 2017 and 2021). The effect of five cover management systems were compared for each agricultural year, namely BS: bare soil in 2015/2016, 2016/2017 and 2017/2021; OBS: olive trees on bare soil in 2015/2016, 2016/2017 and 2017/2021; OSV: olive trees intercropped with mowed spontaneous vegetation in 2015/2016, 2016/2017 and 2017/2021; OJB: olive trees intercropped with jack beans (Canavalia ensiformis L.) in 2015/2016 and 2016/2017, and olive trees crowned intercropped with mowed spontaneous vegetation in 2017/2021; OMI: olive trees intercropped with millet (Pennisetum glaucum L.) in 2015/2016, olive trees intercropped with sunn hemp (Crotalaria juncea L.) in 2015/2017 and olive trees with spontaneous vegetations treated with herbicide (Roundup) in 2017/2021. The soil quality indices (SQI) proved to be sensitive to variations in different types of soil management from the second year of assessment, regarding water erosion. OSV and OJB showed the highest SQI, while OBS showed the lowest values. The SQI demonstrated an inverse correlation with soil and water losses starting from the second year of assessment. This highlights its efficacy in assessment the effects of adopted management on soil quality in the context of water erosion. Moreover, it reinforces the importance of vegetation cover in maintaining soil fertility, resulting in increase of soil organic matter and improving the structuring of Dystrudepts. The attributes that most correlated with the SQI were soil organic matter, effective cation exchange capacity, sum of bases, geometric mean diameter of aggregates, pH and unsaturated soil hydraulic conductivity. These attributes collectively provide valuable insights into soil health and water erosion susceptibility within the olive tree production system.

Machine learning-based soil quality assessment for enhancing environmental monitoring in iron ore mining-impacted ecosystems

In November 2015, a catastrophic rupture of the Fundão dam in Mariana (Brazil), resulted in extensive socio-economic and environmental repercussions that persist to this day. In response, several reforestation programs were initiated to remediate the impacted regions. However, accurately assessing soil health in these areas is a complex endeavor. This study employs machine learning techniques to predict soil quality indicators that effectively differentiate between the stages of recovery in these areas. For this, a comprehensive set of soil parameters, encompassing 3 biological, 16 chemical, and 3 physical parameters, were evaluated for samples exposed to mining tailings and those unaffected, totaling 81 and 6 samples, respectively, which were evaluated over 2 years. The most robust model was the decision tree with a restriction of fewer levels to simplify the tree structure. In this model, Cation Exchange Capacity (CEC), Microbial Biomass Carbon (MBC), Base Saturation (BS), and Effective Cation Exchange Capacity (eCEC) emerged as the most pivotal factors influencing model fitting. This model achieved an accuracy score of 92% during training and 93% during testing for determining stages of recovery. The model developed in this study has the potential to revolutionize the monitoring efforts conducted by regulatory agencies in these regions. By reducing the number of parameters that necessitate evaluation, this enhanced efficiency promises to expedite recovery monitoring, simultaneously enhancing cost-effectiveness while upholding the analytical rigor of assessments.

Testing Biochar’s Ability to Moderate Extremely Acidic Soils in Tea-Growing Areas

Biochar as a by-product of the carbonization of biomass has an inherent potential to modify acidic soils due to its alkaline nature. To explore the mechanism and effectiveness of biochar, a case study was conducted on severely acidic soils from six fields under tea cultivation in a subtropical zone, comparing rice husk biochars, in three rates (B5, B10, B15 t ha−1), and CaCO3 as conventional liming practice. The results showed increases in pH of 71.5%, 52.7%, 30.6%, and 29.7% in B15, B10, B5, and CaCO3-treated soils compared to the control. On average, B15 and B10 treatments resulted in the highest organic matter with 12.3% and 9.7%, respectively. B15, B10, B5, and CaCO3 caused increases of 196.6%, 173.4%, 129.7%, and 100.9% in base saturation compared to the control, respectively. Also, after the application of B15, B10, and B5 treatments, the effective cation exchange capacity increased by 191.4%, 112.1%, and 39.5%; however, the application of CaCO3 resulted in a 20.1% decrease. Overall, applying biochar on acidic soils provides adequate negative charges due to its well-extended specific surface area and pore volume, which cause the absorption of additional Al+, resulting in ameliorating soil pH. The application of proper biochar could notably be more effective in improving acidic soils than conventional practices such as the overuse of CaCO3. In this regard, evaluating various biochars in terms of feedstock, pyrolysis conditions, and modification scenarios merits in-depth research in future studies.

Quantitative analysis of soil degradation in response to land use change in the Guinea savanna zone of Ghana

Soil degradation (SD) poses a significant challenge to tropical agricultural production systems due to its role in depleting soil nutrients. Recently, SD has threatened population growth by causing hunger and poverty among smallholder farmers in the Guinea savanna agro-ecological zone of Ghana. However, SD cannot be directly measured. Instead, assessment and modelling efforts rely on biological and physico-chemical indicators. This study sought to: (i) select a minimum dataset (MDS) using a multivariate statistical technique; (ii) identify SD processes, and evaluate the extent of degradation; and (iii) suggest strategies to monitor SD in the study area. Soil samples were collected using the Land Degradation Surveillance Framework (LDSF), specifically designed for sub-plot level (1000 m2) sampling. This scheme aligns well with the typical farm structure of smallholder farmers (<10 acres). Soil samples, taken from a depth of 0–20 cm, were analyzed to assess their physico-chemical properties. Principal component analysis (PCA) identified seven key SD processes: soil texture, pH, organic carbon (OC), total nitrogen (TN), available phosphorus (Av. P), base saturation (BS) and Effective Cation Exchange Capacity (ECEC). These identified processes lead to the loss of OC, deterioration of soil texture, reduction in soil nutrients, and increased soil acidity. There was a strong positive correlation (r = 0.70, p<0.05) between soil physical and chemical properties. PC1 explained 26.86% of the total variance, followed by PC2 at 15.31%, PC3 at 12.46%, and PC4 at 9.98%. Also, PC5, PC6, and PC7 accounted for 8.49%, 7.25% and 1.42% of the variance, respectively. The land-use systems we identified significantly affected the concentration of soil nutrients (p<0.001). In our computed Composite Soil Degradation Index (CSDI), CEC emerged as the most significant SD indicator with a weight of 0.328, followed by Si:CL ratio at 0.187. The results indicate that soil management activities should focus on increasing organic matter. Soil nutrient depletion primarily occurs through several processes. Land clearing and burning of organic materials during land preparation are primary causes. Furthermore, a total crop removal during harvest, inadequate manure application, and subsequent leaching and erosion aggravates SD, leading to nutrient-depleted soils. We conclude that the loss of nutrients, specifically CEC, OC, Ex. K and Av. P is the primary contributor to chemical SD. Therefore, implementing integrated soil fertility management (ISFM) strategies, such as applying organic (e.g., animal-based manures, green manure, crop residues, compost) and inorganic fertilizers (e.g., NPK + micronutrients) is crucial for increasing soil nutrient availability, enhancing SOM content, and promoting carbon sequestration in these farming systems. This study establishes a baseline for comparing and evaluating the effectiveness of land management interventions at the landscape level in northern Ghana. Consequently, soil nutrient management should be tailored to site-specific conditions, focusing on increasing the efficiency of N, P, K and micronutrient uptake by plants. Adopting such site-specific management strategies could significantly contribute to the sustainable intensification of agricultural production systems in the Guinea Savanna agro-ecological zone of Ghana.

Long-Term Organic Manure Retarding Soil Acidity in the Double-Cropping Rice Field of Southern China

ABSTRACT This paper investigates the effects of different long-term (36 years) fertilizer treatments on soil pH, exchangeable acids, exchangeable base cation and cation exchange capacity (CEC) at 0–10 cm and 10–20 cm soil layers in a double-cropping rice field. The following fertilizer treatments were included: chemical fertilizer (MF), rice straw and chemical fertilizer (RF), 30% organic manure and 70% chemical fertilizer (OM), and without any fertilizer input as a control (CK). This result indicated that soil pH at 0–10 cm layer with RF and OM treatments was higher than that of MF and CK treatments. Soil exchangeable acidity content at 0–10 cm and 10–20 cm layers with RF and OM treatments were decreased by 48.4%, 51.6% and 49.2%, 54.2%, compared with CK treatment, respectively. Soil exchangeable calcium (Ca2+), magnesium (Mg2+) and potassium (K+) contents at 0–10 cm and 10–20 cm layers in paddy field with OM and RF treatments were higher than that of CK treatment. Moreover, compared with CK treatment, soil exchangeable base ion content at 0–10 cm and 10–20 cm layers in paddy field with OM treatment were increased by 54.1% and 42.6%, respectively. Soil CEC and effective cation exchange capacity (ECEC) at 0–10 cm and 10–20 cm layers with OM and RF treatments were significantly higher than that of MF and CK treatments. In conclusion, our results indicated that long-term application of crop residue or organic manure can improve soil exchangeable base ion and exchangeable capacity contents, alleviate soil acidity in a double-cropping paddy field.

Exploring Genomics and Microbial Ecology: Analysis of Bidens pilosa L. Genetic Structure and Soil Microbiome Diversity by RAD-Seq and Metabarcoding.

Bidens pilosa L., native to South America and commonly used for medicinal purposes, has been understudied at molecular and genomic levels and in its relationship with soil microorganisms. In this study, restriction site-associated DNA markers (RADseq) techniques were implemented to analyze genetic diversity and population structure, and metabarcoding to examine microbial composition in soils from Palmira, Sibundoy, and Bogotá, Colombia. A total of 2,984,123 loci and 3485 single nucleotide polymorphisms (SNPs) were identified, revealing a genetic variation of 12% between populations and 88% within individuals, and distributing the population into three main genetic groups, FST = 0.115 (p < 0.001) and FIT = 0.013 (p > 0.05). In the soil analysis, significant correlations were found between effective cation exchange capacity (ECEC) and apparent density, soil texture, and levels of Mg and Fe, as well as negative correlations between ECEC and Mg, and Mg, Fe, and Ca. Proteobacteria and Ascomycota emerged as the predominant bacterial and fungal phyla, respectively. Analyses of alpha, beta, and multifactorial diversity highlight the influence of ecological and environmental factors on these microbial communities, revealing specific patterns of clustering and association between bacteria and fungi in the studied locations.

Soil electrical conductivity as a proxy for enhanced weathering in soils

To effectively monitor and verify carbon dioxide removal through enhanced weathering (EW), this study investigates the use of soil electrical conductivity (EC) and volumetric water content (θ) as proxies for alkalinity and dissolved inorganic carbon (DIC) in soil water. EC-θ sensors offer a cost-effective and straightforward alternative to traditional soil and water sampling methods. In a lab experiment, three different substrates were treated with NaHCO3 solutions to increase the alkalinity of the soil water and analyze the response. The combination of EC and θ to track the increase in carbonate alkalinity due to EW, and therefore CO2 consumption, is applicable for low cation exchange capacity (CEC) soil-substrates like the used quartz sand. However, the presence of organic material and pH-dependent CEC complicates the detection of clear weathering signals in soils. In organic-rich and clay-rich soils, only a high alkalinity addition has created a clear EC signal that could be distinguished from a non-alkaline baseline with purified water. Cation exchange experiments revealed that the used soil buffered alkalinity input and thereby might consume freshly generated alkalinity, initially mitigating CO2 uptake effects from EW application. Effective CEC changes with pH and pH buffering capacity by other pathways need to be considered when quantifying the CO2 sequestration potential by EW in soils. This should be estimated before the application of EW and should be part of the monitoring reporting and verification (MRV) strategy. Once the soil-effective CEC is raised, the weathering process might work differently in the long term.

Soil organic carbon stocks and fertility in smallholder indigenous agroforestry systems of the North-Eastern mountains, Tanzania

Soil organic carbon and soil fertility are critical components of soil health and play a significant role in sustaining agricultural productivity. Indigenous agroforestry practices have been identified as an interesting avenue to sequester carbon and enhance soil fertility in tropical smallholder farms. However, that potential remains poorly quantified. To better understand the dynamics of soil organic carbon stocks and fertility, this study evaluated and compared 4 different smallholder indigenous agroforestry systems (i.e., Kihamba, Ginger, Miraba, and Mixed spices) in the northeastern volcanic and block mountains of Tanzania. Specifically, we compared old and young agroforestry systems in terms of soil organic carbon stocks and soil fertility (proxied by effective cation exchange capacity (eCEC)). In each agroforestry system, a network of old and young tree farm plots were selected for soil sampling at different depths and physico-chemical parameters were analyzed (soil organic carbon, texture, bulk density, pH-H2O, and eCEC). Our findings showed that there was no significant difference between young and old agroforestry systems in terms of soil organic carbon stocks, except in the Kihamba system on the slopes of Kilimanjaro. The highest soil carbon sequestering potential was found in the old Kihamba (located on Nitisols) compared to other systems on Acrisols. Young agroforestry in Ginger and Miraba appeared to have a higher capacity to sequester soil carbon than Mixed spices. Regarding eCEC levels, there was a significant difference between old and young agroforestry systems in both the Kihamba and Miraba system. At the 0–10 cm depth, the highest eCEC levels were found in young agroforestry for Kihamba, Miraba, and Mixed spices. Our results implied that specific management and restoration strategies should focus on optimizing soil fertility and carbon sequestration potential of agroforestry systems in the South Pare and Usambara Mountains characterized by low-fertility Acrisols.

Evaluation of land use impact on soil quality in Samaru College of Agriculture, Northern Guinea Savanna, Nigeria

Abstract Land use changes influence soil quality, which is of fundamental importance in sustainable crop production and environmental management. This study evaluated land use impact on soil quality at Samaru College of Agriculture farm, Ahmadu Bello University, Zaria, Nigeria. The land use types were Tomato/Pepper, Grapevine/Fluted pumpkin, Mango/Orange, and Guava/Mango. A profile pit was dug in each land unit. Soil samples were collected from genetic horizons, prepared, and analysed in the laboratory using standard methods. Sand, silt, and clay differed significantly (p &lt; 0.05) among the land uses. The soil texture varied from clay loam to clay. Bulk density (BD) was significantly (p &lt; 0.05) higher under Mango/Orange and Guava/Mango than other land use types. The soil reaction (pH) ranged from 5.0 to 5.8 and was strongly to moderately acidic. Soil organic carbon was low (&lt; 10 g/kg), total nitrogen values of 0.19 – 0.24 g/kg were low, and available phosphorus values of 1.8 – 27.4 mg/kg were rated low to high across the land use types. Soils under the Grapevine/Fluted pumpkin land use type were significantly higher in organic carbon, exchangeable potassium, sodium, and effective cation exchange capacity than the other land use types. Soil quality under Grapevine/Fluted pumpkin was rated best (80 %), whereas soil quality under Tomato/Pepper land use type was the worst (40 %). The soils were low-to-high in quality and had a higher potential to support crop production if management practices that encourage the build-up of nutrients in the soil system were adopted. The application of manure, liming materials, and phosphorus-based fertilisers is advocated.

Crop production potential of reclaimed mine sites for sustainable livelihoods

Purpose: Potentiality of six reclaimed mine sites for crop production at Goldfields Ghana Limited, Tarkwa Mine was holistically assessed. Research methodology: Soil pH was traced using HI 9017 microprocessor meter while total nitrogen (TN), organic matter (OM) and organic carbon (OC) were determined by Kjeldahl digestion, distillation and Walkley-Black Methods. Calcium (Ca), magnesium (Mg), potassium(K), sodium (Na), were further determined in 1.0 M ammonium acetate (NH4OAc) extract, using hydrogen and aluminum in 1.0 M KCl, by EDTA titration and flame photometry. Results: Optimum soil pH, compared with other parameters down the trend was less than 4.33. In cmolkg-1, OM at Ajopa natural forest soil (2.52) was greater than West Heap (2.08). TN differed significantly (p ? 0.001) such that, Ajopa natural forest (0.13%) was greater than West Heap (0.11%). West Heap Ca (3.52) was greater than Bridge Dump Ground (BDG’s) (1.78) while Mg (1.25) at BDG was greater than West Heap (1.22). West Heap’s K (0.16) was greater than BDG’s (0.13). Sodium was entirely low (&lt; 5 %). But acidity of Ajopa natural forest (1.90) was greater than BDG’s (1.89) while effective cation exchange capacity (ECEC) of West Heap (5.95) was greater than BDG’s (4.68). Limitation: Study sites sparsely located and require more experience to locate sampling points. Contribution: Analyses clearly revealed poor agglomeration of cation exchange capacities due to inadequate fertility of the seven-year old reclaimed mine sites. Hence, it may not give good crop yields for sustainable economic livelihoods strategies without long-term augmented fertilization and liming.

Tetracycline adsorption/desorption by raw and activated Tunisian clays

Clay-based adsorbents have applications in environmental remediation, particularly in the removal of emerging pollutants such as antibiotics. Taking that into account, we studied the adsorption/desorption process of tetracycline (TC) using three raw and acid- or base-activated clays (AM, HJ1 and HJ2) collected, respectively, from Aleg (Mazzouna), El Haria (Jebess, Maknessy), and Chouabine (Jebess, Maknessy) formations, located in the Maknessy-Mazzouna basin, center-western of Tunisia. The main physicochemical properties of the clays were determined using standard procedures, where the studied clays presented a basic pH (8.39–9.08) and a high electrical conductivity (446–495 dS m−1). Their organic matter contents were also high (14–20%), as well as the values of the effective cation exchange capacity (80.65–97.45 cmolckg−1). In the exchange complex, the predominant cations were Na and Ca, in the case of clays HJ1 and AM, while Mg and Ca were dominant in the HJ2 clay. The sorption experimental setup consisted in performing batch tests, using 0.5 g of each clay sample, adding the selected TC concentrations, then carrying out quantification of the antibiotic by means of HPL-UV equipment. Raw clays showed high adsorption potential for TC (close to 100%) and very low desorption (generally less than 5%). This high adsorption capacity was also present in the clays after being activated with acid or base, allowing them to adsorb TC in a rather irreversible way for a wide range of pH (3.3–10) and electrical conductivity values (3.03–495 dS m−1). Adsorption experimental data were studied as regards their fitting to the Freundlich, Langmuir, Linear and Sips isotherms, being the Sips model the most appropriate to explain the adsorption of TC in these clays (natural or activated). These results could help to improve the overall knowledge on the application of new low-cost methods, using clay based adsorbents, to reduce risks due to emerging pollutants (and specifically TC) affecting the environment.

Soil δ15N spatial distribution is primarily shaped by climatic patterns in the semiarid Caatinga, Northeast Brazil

Soil nitrogen isotopic composition (δ15Nsoil) is an invaluable tool as it integrates nitrogen (N) transformations in soils. In addition to serving as a baseline to understand the N cycle, spatial representations of δ15Nsoil across landscapes (or isoscapes) is a multi-purpose tool useful to investigate, for example, plant-microbe interactions, animal migration and forensics. We investigate the climatic and edaphic controls of δ15Nsoil utilising data from 29 geographical locations sampled across the semiarid Brazilian Caatinga biome. The sampling covered a mean annual precipitation (PA) gradient ranging from 0.51 to 1.36 m a−1 and eight soil types originating from three different geological origins. Our data show that the combination of higher aridity and lower seasonality (ψ) leads to higher values of δ15Nsoil. Moreover, soil total carbon had a positive relationship with δ15Nsoil, appearing within the best-supported models according to the information-theoretic approach undertaken here. The contribution to the plant communities by the Fabaceae trees expressed as their basal area was not related to δ15Nsoil values, suggesting that the magnitude of biological N fixation in the Caatinga is not large enough to be reflected in the soil. In addition, considering PA in a categorical fashion, i.e., ‘high’ (> 0.8 m a−1) and ‘low’ PA (< 0.8 m a−1), we found that, within the wetter category, δ15Nsoil was positively related to several soil properties (i.e., clay content, effective cation exchange capacity, exchangeable calcium, silt content, pHH2O, total phosphorus and sum of bases) and negatively related to sand content. Our study provides new insights into the functioning of semiarid ecosystems from a pedo-isotopic perspective and contributes to the overall understanding of the N cycle in the Caatinga region, with the potential to support the development of new conceptualisation of biogeochemical process and testing of global models that simulate N and C cycles.

Investigation into the Chemical Characteristics of Soils near Sinkholes Situated in Anambra State, Nigeria

In this comprehensive study, we delve into the chemical properties of soil in the proximity of sinkholes located in Anambra state of Nigeria. Three distinct sinkhole sites were selected for examination: Awka site 1 (6.2232°N and 7.0824°E), Awka site 2 (6.2220°N and 7.0819°E), and Agulu (6.0941°N and 7.0203°E). For a comprehensive analysis, 24 soil samples were meticulously collected and subjected to thorough analysis. These samples comprised of 15 specimens obtained from the immediate vicinity of the sinkholes, while 9 samples were procured from locations situated at least 2 kilometers away from the sinkhole sites. The study focused on investigating various parameters, namely pH levels, Organic Carbon (OC) content, Organic Matter (OM) content, Aluminum (Al) levels, Hydrogen (H) levels, Total Nitrogen (TN) content, Magnesium (Mg) levels, Potassium (K) levels, Sodium (Na) levels, Calcium (Ca) levels, Effective Cation Exchange Capacity (ECEC), Base Saturation, and soil texture. The obtained results revealed that the study areas predominantly exhibited a sandy composition with a notably low clay content. Furthermore, the analysis indicated low hydrogen values, while sodium levels were observed to be relatively high. Consequently, certain areas, particularly those situated farther away from the sinkhole site, exhibited a reduced amount of exchangeable bases and effective cation exchange capacity. This phenomenon potentially resulted in leaching and dispersion within the soil, leading to inadequate water infiltration and subsequent run-off. Notably, this process may have contributed to the formation of tunnel erosion, ultimately resulting in the emergence of sinkholes.

Empirical model to assess leaching of pesticides in soil under a steady-state flow and tropical conditions

An empirical model of leaching of pesticides was developed to simulate the concentration of fungicides throughout unsaturated soil. The model was based on chemical reactions and the travel time of a conservative tracer to represent the travel time required for water to flow between soil layers. The model’s performance was then tested using experimental data from dimethomorph and pyrimethanil applied to the soil under field and laboratory conditions. The empirical model simulated fungicide concentration on soil solids and in soil solution at different depths over time (mean square error between 2.9 mg2 kg−2 and 61mg2 kg−2) using sorption percentages and degradation rates under laboratory conditions. The sorption process was affected by the organic carbon, clay, and the effective cation exchange capacity of the soil. The degradation rate values of dimethomorph (0.039 d−1–0.009 d−1) and pyrimethanil (0.053 d−1–0.004 d−1) decreased from 0 to 40 cm and then remained constant in deeper soil layers (60–80 cm). Fungicide degradation was a critical input in the model at subsurface layers. The model was determined to be a reliable mathematical tool to estimate the leachability of pesticides in tropical soil under a steady-state flow. It may be extended to other substances and soils for environmental risk assessment projects.Graphical abstract

Determining relative values of pH, CECe, and OC in agricultural soils using functional enhanced derivative spectroscopy (FEDS0) method in the mid-infrared region

Soils are a vital and non-renewable natural resource that provide the nutrients and adequate conditions for plants growth, as well to support several economic activities. Optical spectroscopy has emerged as a reliable technique for determining multiple physicochemical properties of organic and inorganic species in agricultural industries, that employs mathematical and statistical tools to develop new methodologies of spectral analysis easily implementable in remote and in-field applications. This is the case of the Functionally-enhanced derivative spectroscopy (FEDS and FEDS0), which uses operational transformations to extract hidden information from overlapping optical signals generated by the diverse components of solid and liquid matrices. In this study, an algorithm based on FEDS has been applied for optical analysis of agricultural soils in the spectral range from 1200 to 675 cm−1, to estimate chemical properties related to nutritional and fertility state of 65 soil samples used for planting of cotton, yuca (Manihot Esculenta), and banana in Bolivar and Cordoba departments in Colombia. The results demonstrate that it is possible to establish a correlation between the Pearson’s coefficient obtained from two FEDS0 spectra associated to ATR-FTIR signals (rF > - 0.85), and their relative values of effective cation exchange capacity, pH and organic carbon content, with a ratio of performance to deviation higher to 2.0 in all cases (RPD > 2.0). This is possible due to high dependence of optical signal with CECe values, which are in turn conditioned by pH level and OC content in the soil samples considered.

The Physicochemical Properties and Microbial Populations of Nicosulfuron Treated Soil in Yola, Adamawa State, Nigeria

The use of herbicides in the modern system of farming has really help in boosting crop production, this way meeting up with the ever increasing demand for food by the always increasing human population. However, these herbicides have different mode of actions and effect on soil components; and their continued usage has affected the soil microbial communities and other soil components most of which are the non-target. This study, therefore, was focused on evaluating the physicochemical properties and microbial population of nicosulfuron treated soils of Yola, Adamawa State, Nigeria. The study was carried out in both 2021 and 2022 in the Research Farm of the Department of Plant Science, Modibbo Adama University, Yola. The samples of the soil treated with the different concentrations of nicosulfuron were obtained at 0, 2, 4 and 6 Weeks after Treatment (WAT) at the depth between 0-12 cm. The physicochemical properties and the bacterial and fungal populations of the collected soil samples were determined using standard laboratory procedures. The results revealed that the soils treated with the 50, 100, 150 and 200 g/ha concentrations of nicosulfuron had a comparable values for physicochemical (except percentage moisture content, organic carbon and matter and total nitrogen) properties that include: pH, electrical conductivity, Calcium, magnesium and potassium ions, total exchangeable acidity, total exchangeable base, effective cation exchange capacity, percentage base saturation. On the basis of duration of application, however, the nicosulfuron had significant effect on the physicochemical properties with 6 WAT having the highest values for the physicochemical properties compared to other sampling durations. On the bacterial (except the fungal) population, the nicosulfuron also had a significant effect with the treated soils having the lowest populations of both bacteria and fungi. The study therefore, concluded that the duration of application of nicosulfuron have significant effect on physicochemical properties of soil in Yola. On the bacterial and fungal populations of the soil, nicosulfuron also had significant effect.

Comparison of five methods to determine the cation exchange capacity of soil

AbstractBackgroundCation exchange capacity (CEC) is a routinely measured soil fertility indicator. The standard NH4OAc (pH 7) extraction procedure is time‐consuming and overestimates actual CEC values of variable charge soils. Unbuffered extractants have been developed to measure the effective CEC (eCEC), but they differ in the type of index cation and extraction procedures.AimThis study was set up to systematically compare CEC values and exchangeable cation concentrations among different procedures and evaluate their practical aspects.MethodsFive procedures were compared for (e)CEC, that is, silver thiourea (AgTU), cobalt(III) hexamine (Cohex), compulsive exchange (CE, i.e., BaCl2/MgSO4), BaCl2 (sum of cations in single‐extract), and NH4OAc (pH 7). We applied these methods to a set of 25 samples of clay minerals, peat, or samples from soils with contrasting properties.ResultsThe CEC values correlated well among methods (R2 = 0.92–0.98). Median ratios of eCEC (AgTU as well as CE) to the corresponding eCEC (Cohex) value were 1.0, showing good agreement between eCEC methods, but NH4OAc exceeded Cohex values (ratios up to 2.5 in acid soil). For BaCl2‐extracteable cations, the ratio ranged from low (&lt;1.0) in acid soils (acid cations not measured) to high (&gt;1.0) in high‐pH soil (dissolution of carbonates). Multiple‐extraction methods (CE and NH4OAc) yielded more variation and increased labor.ConclusionsThe chemical properties of the sample cause method‐specific interactions with chemical components of extractants. We found the Cohex method with ICP‐MS detection to be the most efficient and cost‐effective technique for determination of eCEC and exchangeable cations.

Mechanism of Al toxicity alleviation in acidic red soil by rice-straw hydrochar application and comparison with pyrochar

In the past decade, biochar has been widely regarded as a new type of soil conditioner that can effectively control soil acidification and alleviate Al toxicity. Hydrochar is identified as a more economical carbon material than pyrochar, but its effect on Al toxicity and the associated mechanism have not been studied. Thus, a two-stage indoor incubation experiment was conducted to investigate the effect of rice-straw hydrochar (HC, application rate: 1/2/3 %) on maize seedling root growth, soil solution Al activity, soil exchangeable Al and pH buffering ability in acidic red soils from two sites. We also used pyrochar (PC, application rate: 3 %) produced from the same rice straw for comparison. Except for HC-1 %, both hydrochar and pyrochar addition significantly stimulated relative root elongation (136.36 % ~ 284.09 %), diminished the cell death ratio (27.96 % ~ 85.56 %) and Al content in root tips (18.80 % ~ 80.11 %) by decreasing the total Al content (44.78 % ~ 76.10 %) and the proportion of Al3+ species (27 % ~ 32 %) in soil solution. Hydrochar did not significantly promote the soil pH buffer capacity (pH-BC) or effective cation exchange capacity (ECEC), while PC-3 % did. The DOC (dissolved organic carbon) content of soil solution was dramatically elevated by 203.9 % ~ 783.2 % after hydrochar addition. Hydrochar mitigates Al activity in soil solution mainly through Al-DOC complexation and adsorption, thus suppressing the Al toxicity of maize roots. Hydrochar may be an economical soil amendment for ameliorating Al toxicity despite its overall alleviation effect on Al toxicity being lower than pyrochar.

Australian soil microbiome: A first sightseeing regional prediction driven by cycles of soil temperature and pedogenic variations.

Declines in soil multifunctionality (e.gsoil capacity to provide food and energy) are closely related to changes in the soil microbiome (e.g., diversity) Determining ecological drivers promoting such microbiome changes is critical knowledge for protecting soil functions. However, soil-microbe interactions are highly variable within environmental gradients and may not be consistent across studies. Here we propose that analysis of community dissimilarity (β-diversity) is a valuable tool for overviewing soil microbiome spatiotemporal changes. Indeed, β-diversity studies at larger scales (modelling and mapping) simplify complex multivariate interactions and refine our understanding of ecological drivers by also giving the possibility of expanding the environmental scenarios. This study represents the first spatial investigation of β-diversity in the soil microbiome of New South Wales (800,642 km2 ), Australia. We used metabarcoding soil data (16S rRNA and ITS genes) as exact sequence variants (ASVs) and UMAP (Uniform Manifold Approximation and Projection) as the distance metric. β-Diversity maps (1000-m resolution)-concordance correlations of 0.91-0.96 and 0.91-0.95 for bacteria and fungi, respectively-showed soil biome dissimilarities driven primarily by soil chemistry-pH and effective cation exchange capacity (ECEC)-and cycles of soil temperature-land surface temperature (LST-phase and LST-amplitude). Regionally, the spatial patterns of microbes parallel the distribution of soil classes (e.g., Vertosols) beyond spatial distances and rainfall, for example. Soil classes can be valuable discriminants for monitoring approaches, for example pedogenons and pedophenons. Ultimately, cultivated soils exhibited lower richness due to declines in rare microbes which might compromise soil functions over time.

Fertility capability classification of selected soils on the basement complex of north-eastern Nigeria

A clear understanding of soil characteristics and their appropriate classification are essential for efficient land use and increased productivity. The present study was carried out to obtain the fertility capability classification (FCC) of the soils overlying the basement complex in a toposequence in north eastern Nigeria and to serve as baseline data for soil management. Soils on four topographic positions identified on porphyritic granite (PG), pegmatite (PT) and granite-gneiss (GG) of the basement complex in Taraba State of Nigeria were assessed. Twelve pedons were studied in all, four along the toposequence on PG, PT, and GG. At the type and substrata type, sandy and loamy group dominated. Ustic soil moisture regime, exchange acidity (fixing available phosphorus) and low organic carbon limited the entire soils across the basement complexes restricting rainfed crop production to one season per annum except with irrigation practice. Poor drainage was a limitation across the soils on pegmatite. The FCC rated PG and GG soils as SLdeam (sand over loam and limited by moisture, effective cation exchange capacity, aluminium toxicity and organic carbon) and Ldam (loam type and substrata characteristics limited by moisture, aluminium toxicity and organic carbon), and PT and PT soils as Sdamg (sandy type and substrata type restricted by moisture, aluminium toxicity, organic carbon, drainage). Ridge construction, organic and mineral fertilizer applications are essential management practices required for sustainable use of these soils.