CEC Values Research Articles

Effects of land use types on the soil physicochemical characteristics of Inyi community, Enugu State, Nigeria: Application of multivariate statistical, and eco-toxicological and human risk model approaches

The constant and increased use of arable lands for cultivation has led to its degradation; hence the impacts of different land-use patterns on the soil physical and chemical properties were investigated. Soil samples (n = 36) were collected from the oil palm plantation (OPP), cashew plantation (CP) and untampered forest (UF), in Inyi community, Enugu State, Nigeria. They were air-dried, sieved, and analyzed for their physicochemical properties. The results revealed that the average soil pH ranged from 5.9 to 8.2. Moisture and carbon contents ranged from 6.3 to 35.4, and 3.5 to 6.7 % respectively. Low CEC values were recorded for all the soil samples. The total mean soil textural fractions decreased as follows: sand > clay > silt. Also, the total mean concentrations of N, P, K, and Mg in the study area decreased in the order: OPP>UF>CP, OPP>UF>CP, UF>OPP>CP, and OPP>UF>CP respectively while the S, NO3-, NO2-, and HCO3- followed the order; OPP>UF>CP, UF>OPP>CP, OPP>CP>UF, and CP>OPP>UF respectively. The soil ecological risk index was < 40 in all sample locations, indicating slight contamination of the study area. Therefore, regular monitoring and soil nutrient management practices should be maintained and encouraged.

Annual Flood Phenomenon and Fertility Status of Rice Soil in The Coastal Area of Bengkulu

[ANNUAL FLOOD PHENOMENON AND FERTILITY STATUS OF RICE SOIL IN THE COASTAL AREA OF BENGKULU]. The rice fields in Rawa Makmur Village were agricultural land that was affected by annual floods. Soil fertility status is important for increasing the productivity of paddy. The research aimed to get the fertility status of soil affected by annual flood disasters, evaluating and mapping the distribution of soil fertility status at the research location. The methods used in this research include survey and soil testing methods at the Soil Science Laboratory, Faculty of Agriculture, Bengkulu University. Further evaluation of soil fertility status is in accordance with technical instructions from the Soil Research Center, Bogor (1995). This research was conducted in June – August 2023. The soil CEC value from each sampling point was classified as high with values ranging from 28.15 me/100 g - 39.83 me/100 g. The base saturation value in the study was classified as very low to moderate with values ranging from 11.49% - 40.08%. Soil organic C at the research location from each sampling point was classified as moderate to very high with values ranging from 2.42% - 5.97%. The soil phosphorus content at the research locations observed was classified as very low to low with values ranging from 2.69 mg/100 g – 12.11 mg/100 g. The soil potassium content at each sample point at the research location observed was classified as very low with values ranging from 0.14 mg/100 g – 1.43 mg/100 g. The research results show that the flood phenomenon has a significant impact on soil fertility. The soil fertility status at the research location is classified as low. Soil fertility parameters which are limiting factors in the status of soil fertility in Rawa Makmur Village are phosphorus, potassium and pH. So it is necessary to add P and K fertilizer to improve the soil fertility status.

SPENT BLEACHING EARTH-BIOPROCESS (SBE) CHARACTERISTICS AGAINST INDONESIAN NATIONAL REGULATION FOR TOXIC-HAZARD WASTE AND SOIL AMENDMENT

&lt;p&gt;Currently, the palm oil industry disposes the Spent Bleaching Earth (SBE) to the land-field without a proper treatment process. Some peoples argue that the SBE still in high oil content and will pose an environmental problem due to hazardous content and it will easily catch fires. One possible solutions is optimizing SBE for land restoration, which could also be enhancing livelihood and reducing pollution. This paper identifies the SBE-bioprocess according to the Indonesian National Regulation for toxic-hazard waste and soil rehabilitation. SBE-bioprocess testing was conducted as toxic-hazard waste both on TCLP organic and anorganic form also as a soil amendment criteria both certain function and organic. Research shows that the SBE-bioprocess could not be categorized as toxic-hazard waste due to very low value of toxic and hazard compounds. Additional C-organic is important before using it as an organic soil amendments. Lab test shows that SBE-bioprocess is high value of CEC, then could be developed for specific function of soil amendments.&lt;/p&gt;

Assessment of Soil Fertility Status of the Soils of KVK -Muzaffarnagar, Uttar Pradesh, India

The present study was undertaken to assess the soil fertility status of the soils of KVK Muzaffarnagar. Soil samples were collected from two depths viz., 0-15 cm and 15-30 cm and analysed for various soil properties. Results revealed that soils were sandy loam in texture, neutral to slightly alkaline in reaction, non-saline and low in soil organic carbon content. Mean values of CEC, SOC, available nitrogen, available phosphorus, available potassium and available sulphur were 11.22 and 9.62 C mol (p+) kg-1, 0.17 and 0.13 g kg-1, 260.16 and 208.14 kg ha-1, 30.86 and 27.30 kg ha-1, 100.94 and 107.89 kg ha-1 and 13.51 and 12.84 kg ha-1 recorded at 0-15cm and 15-30 cm depth, respectively. The mean of DTPA extractable zinc, DTPA extractable iron, DTPA extractable manganese and DTPA extractable copper were 0.28 and 0.31 mg kg-1, 0.97 and 1.22 mg kg-1, 2.14 and 1.78 mg kg-1 and 0.23 and 0.19 mg kg-1 recorded surface and sub-surface depths, respectively. Soils are low in available nitrogen and potassium and medium in available phosphorus status. Cationic micronutrients such as iron, copper and zinc contents were found deficient in range, whereas manganese content was found to be sufficient.

Spatial distribution of Pb and Zn in soils under native vegetation in Southeast Brazil.

Heavy metals can play an important biological role as micronutrients but also as potentially toxic elements (PTEs). Understanding the natural concentrations of PTEs-Pb and Zn included-in soils allows for the identification and monitoring of contaminated areas and their role in environmental risk assessment. In this study, we aim to determine semi-total or natural and available concentrations of Pb and Zn in topsoils (0-20 cm depth) from 337 samples under native vegetation in the State of Minas Gerais, Brazil. Additionally, we sought to interpret the spatial geochemical variability using geostatistical techniques and quality reference values for these elements in soils were established. The semi-total concentrations were determined by flame and graphite furnace atomic absorption after microwave-assisted nitric acid digestion method. The available concentrations were extracted using the Mehlich-I extractor and determined by atomic absorption spectrometer. Spatial variability was modeled using semivariance estimators: Matheron's classic, Cressie and Hawkins' robust, and Cressie median estimators, the last two being less sensitive to extreme values. This allowed the construction of digital maps through kriging of semi-total Pb and Zn contents using the median estimator, as well as other soil properties by the robust estimator. The dominance of acidic pH and low CEC values reflects highly weathered low-fertility soils. Semi-total Pb contents ranged from 2.1 to 278 mg kg-1 (median: 9.35 mg kg-1) whereas semi-total Zn contents ranged from 2.7 to 495 mg kg-1 (median: 7.7 mg kg-1). The available Pb contents ranged from 0.1 to 6.92 mg kg-1 (median: 0.54 mg kg-1) whereas available Zn contents ranged from 0.1 to 78.2 mg kg-1 (median: 0.32 mg kg-1). The highest Pb and Zn concentrations were observed near Januária, in the northern part of the territory, probably on limestone rocks from the Bambuí group. Finally, the QRVs for Pb and Zn in natural soils were lower than their background values from other Brazilian region and below the prevention values suggested by Brazilian environmental regulations.

Salicylic Acid with Humic Acid Addition as Potential Hallmarks for Alleviating Drought Stress in Maize Crop and Enhancing Soil Health

Climate change is the biggest concern to the human kind and threat to agri-food security. Deficiency of water in soil and the ability of plants to uptake water is slowed down due rising temperature and microbial imbalance in soil. Salicylic acid plays an important role in mitigating drought stress and improves the overall production of crop. Humic acid is another amendment to cope against water stress and optimizes the yield. Apart from that, there is little known about their impact on soil geochemistry and that how soil health is altered.&#x0D; To investigate the effect of salicylic acid and humic acid on the drought experiment was conducted at University Research Farm (URF), PMAS Arid Agriculture University, Rawalpindi during summer 2023. The experiment was set up in randomized complete block design in two factorial arrangements with four replications. The first factor was comprised of mitigation strategies; salicylic acid, humic acid and chemical fertilizer, while second factor was water regimes; water stress and irrigation maintaining 60% field capacity.&#x0D; Plant attributes including chlorophyll content (SPAD value), total soluble protein content (mg/g), total free amino acid (mg/g), K+ content (mg/g), Na+ content (mg/g), 1000 grain weight (g) and grain yield (kg/ha) were measured and reported. On the other hand, soil parameters that were estimated are: soil pH, soil organic matter content (%), available N (ppm), available P (ppm), available K (ppm) and cation exchange capacity (cmol/kg).&#x0D; According to the data analysis, all of the features under study had a substantial impact from the mitigation approaches. The increased value of chlorophyll content (49.11 mg/g) was obtained in water stressed condition by the application of salicylic acid. Under water stressed regime and salicylic acid boosted the total soluble protein content (1.67 mg/g) and total free amino acid (31.93 mg/g) while grain yield (9451.7 kg/ha) was also boosted up by the amendment salicylic acid in maize. There was also increase in the values of soil pH (6.78), CEC (54.37 cmol/kg), SOM content (0.87%), available N (3.24 ppm), available P (26.14 ppm) and available K (211.23 ppm) drought conditions with the implementation of salicylic acid.&#x0D; Humic acid also positively impacted the drought stress and improved the maize yield (8436.2 kg/ha) under drought condition. Similarly, soil nutrient retention is also improved to large extent under water stress state; SOM content (0.49%), available N (2.36 ppm), available P (15.67 ppm) and available K (171.94 ppm).&#x0D; Overall, the study showed that amendment of salicylic acid and humic acid, is the greatest strategy to increase crop production and quality while also improving the health of the soil.

Transport of sulfanilamide in saturated porous media under different solution chemistry conditions: role of physicochemical characteristics of soils.

Identification of the transport of sulfonamide antibiotics in soils facilitates a better understanding of the environmental fate and behaviors of these ubiquitous contaminants. In this study, the mobility properties of sulfanilamide (SNM, a typical sulfonamide antibiotic) through saturated soils with different physicochemical characteristics were investigated. The results showed that the physicochemical characteristics controlled SNM mobility. Generally, the mobility of SNM was positively correlated with CEC values and soil organic matter content, which was mainly related to the interactions between the organic matter in soils and SNM molecules via π-π stacking, H-bonding, ligand exchange, and hydrophobic interaction. Furthermore, higher clay mineral content and lower sand content were beneficial for restraining SNM transport in the soils. Unlike Na+, Cu2+ ions could act as bridging agents between the soil grains and SNM molecules, contributing to the relatively weak transport of SNM. Furthermore, the trend of SNM mobility in different soil columns was unaffected by solution pH (5.0-9.0). Meanwhile, for a given soil, the SNM mobility was promoted as the solution pH values increased, which was caused by the enhanced electrostatic repulsion between SNM- species and soil particles as well as the declined hydrophobic interaction between SNM and soil organic matter. The obtained results provide helpful information for the contribution of soil physicochemical characteristics to the transport behaviors of sulfonamide antibiotics in soil-water systems.

The Effects of Various Land Use Types on Particular Physicochemical Characteristics of the Soil in Mante Watershed, South Regional Government of Ethiopia

Soil quality is threatened when the forest cover is replaced by cultivated and grazing lands in Mante watershed found in South Ethiopia. The study aimed to ascertain how different land use patterns and slope gradients affected the physicochemical characteristics of the soil. The watershed was stratified according to the predominant land use types, namely, grazing land, cultivated land, and forest lands with slope gradient variations to choose sites for soil sampling. Three slope classes were used to categorize the catchments of the watershed: 0–15%, 15–30%, and &gt;30%. In soil depths of 0–20 cm and 20–40 cm, fifty‐four (54) composite soil samples were taken (3 land use types × 3 slope classes × 2 soil depths × 3 replications). The results showed that the highest mean values of total nitrogen, available phosphorus, CEC, Ca, K, Mg, and Na were high but pH was low under forest lands and slope gradients of &gt;30% but cultivated lands with the lowest mean values found in the range of 0–15% slopes. Regarding soil depth, the upper layer (0–20 cm) had higher mean values for silt fraction, pH, CEC, and Mg, while the lower layer (20–40 cm) had lower mean values. The soil quality was higher under the forests because Na had a greater significance in the upper soil layer and a lower value in the lower soil layer. The decline in the soil quality under the cultivated land suggests that integrated soil and water management is necessary to maintain the favorable soil physicochemical properties and replenish the degraded soil.

STUDY SOIL DEVELOPMENT AND CLASSIFICATION IN ERBIL PROVINCE, KURDISTAN, IRAQ USING MATHEMATICAL INDICES

The study area located at Erbil province, Kurdistan, Iraq, seven pedons were elected. Twenty-one soil samples were collected in the study area. Different physiochemical and fertility indices have been used to determine the soils development, despite of generating interpolated maps for them. The results indicated that the low values of clay were found in the less pedon developed and argillic horizon existed in development pedons. Study soils were non-saline, slightly to moderately alkaline, and had relatively high bulk density values. Organic matter is concentrated at the soil surface. Considerable total carbonates are found in studied soils and have irregular distribution manner, as well as have high CEC values. Low C/N ratio due to highly decomposed organic matter. The active CaCO3/total CaCO3 increases with depth in all pedons, while, slightly fluctuated in one pedon. The ratio of total clay in BH /AH was found just in some pedons and more than (1) therefore these soils are considered development, and are more developed depending on the ratio of fine clay/total clay. Soils are classified into three groups the first was the least developed soils, the second group has the most development. Third group are intermediate in their development. Pedogenic processes included leaching, illuviation, eluviation, alkalization, humification, lessivage, desalinization, calcification, decomposition, and littering. Studied soils classified as Inceptisols and Mollisols.

Improved Dual-Population Genetic Algorithm: A Straightforward Optimizer Applied to Engineering Optimization

Aiming at the current limitations of the dual-population genetic algorithm, an improved dual-population genetic algorithm (IDPGA) for solving multi-constrained optimization problems is proposed by introducing a series of strategies, such as remaining elite individuals, a dynamic immigration operator, separating the objective and constraints, normalized constraints, etc. We selected 14 standard mathematical benchmarks to check the performance of IDPGA, and the results were compared with the theoretical value of CEC 2006. The results show that IDPGA with the current parameters obtains good solutions for most problems. Then 6 well-known engineering optimization problems were solved and compared with other algorithms. The results show that all of the solutions are feasible, the solution precision of IDPGA is better than other algorithms, and IDPGA performs with good efficiency and robustness. Meanwhile, no parameters need to be ignored when IDPGA is applied to solving engineering problems, which is enough to prove that IDPGA is suitable for solving engineering optimization. A Friedman test showed no significant difference between IDPGA and six algorithms, but significant differences between IDPGA and seven other algorithms; thus, a larger number of evaluators will be needed in the future. In addition, further research is still needed about the performance of IDPGA for solving practical large-scale engineering problems.

Assessment and Characterization of Agricultural Salt-Affected Soils around Abaya and Chamo Lakes, South Ethiopia Rift Valley

Soil salinity/sodicity is becoming a challenge for crop production in Ethiopia’s semi-arid and arid regions. However, more information on soil salinity/sodicity needs to be available around Abaya and Chamo Lakes, South Ethiopia Rift Valley. This study aimed to assess and characterize soil salinity/sodicity and determine salt-affected soils’ morphological, physical, and chemical properties. The representative soil pits that were 60 ∗ 60 ∗ 60 cm in size were examined, and samples were taken from 0–20, 20–40, and 40–60 cm depths based on the criteria set for agricultural salt-affected soil studies. The soil properties determined include soil color, structure, consistency, bulk density, particle density, porosity, texture, pH, EC, SAR, ESP, CEC, BS, OC, TN, available P, CaCO3−, exchangeable bases, and soluble ions (Na+, Ca2+, Mg2+, K+, Cl−, SO4−2, NO3−, CO3−2, and HCO3−. The soil-analyzed results were rated and interpreted following a guide to standardized analysis methods for soil data. The results of this study reveal that the soils had considerable heterogeneity in soil morphological, physical, and chemical properties. The soils of the study site were highly alkaline and had very high sodium content, very high CEC value, and low levels of organic carbon and exchangeable calcium. The dominant soluble cation was sodium, followed by magnesium, calcium, and potassium in all soil depths of the pits. Similarly, Cl− was dominant among the anions throughout the soil depth, followed by HCO3−, SO42−, and NO3−. The findings of this study imply that removing sodium and salts from the soil depth may improve the salt-affected soils’ productivity in the study area. Application of organic amendments, including manures and crop residues, may also be beneficial in increasing fertility and organic matter content.

The effect of soil management method on some characteristics of limestone soils in the Muthanna desert

Four areas were selected in the Al-Rehab region, the desert of Muthanna Governorate, which differs in the management style, the duration of agricultural exploitation, and the quality of irrigation water. It was taken in each Pedon region, and the morphological and chemical measurements were revealed and conducted. It was found that the thickness of the A horizon ranged between 10-15 centimeters and the thickness of the B horizon between 25-45 centimeters in all study pedons. The administration style did not affect Hue, as all horizons were within the color (10YR) and chroma, as the colors ranged from light white to very bale brown (10 YR7/4) and white (10YR8/1), the soil texture was between Sandy loam, Sandy clay loam, Loamy Sand. As for the chemical properties, the percentage of lime CaCO3 ranged between (250-400) gm/km-1 and the percentage of gypsum ranged between (1.2-1.8) g. km-1 The electrical conductivity EC ranged between (3.9-18)ds.m-1 , while the organic matter was between (2.1- 13.5) and the CEC values ranged between (12-18Coml.kg). Keywords: soil management, calcareous soils

Adsorption Isotherm and Kinetic Modeling of the Congo Red (CR) and Indigo Carmine (IC) Dyes Removal onto Novel Bentonite Hybrid Material

AbstractThe present study focuses on investigating the adsorption characteristics of anionic Congo Red (CR) and Indigo Carmine (IC) dyes using hexadecyltrimethyl ammonium bromide‐modified Bentonite (HDTMA‐Bentonite) with varying loading amounts. The removal effectiveness of anionic dyes was examined as a function of the HDTMA+ loaded amount, contact time, initial concentration, and adsorbent dosage. The XRD data revealed that the interlayer spacing of Bentonite increased from 1.42 to 1.98 nm. The FTIR approach was used to analyze the surface modification of hybrid Bentonite; however, the hydrophobic nature of hybrid Bentonite was confirmed by ATG measurements. A kinetic investigation of sorption was done. The results demonstrated that the pseudo‐second‐order model fitted the adsorption kinetic data better than the pseudo‐first‐order rate equation, and that the amount of HDTMA+ loaded affects the adsorption capacity. According to the Weber‐Morris intra‐particle diffusion equation, the CR and IC dyes diffused faster as the amount of added cationic surfactant rose from 0 % to 100 % of the CEC value. Temkin and Langmuir equation is found to best represent the equilibrium data for two dye‐HDTMA‐B systems. Hybrid Bentonite was regenerated by NaOH, and reused without a significant decrease in its sorption efficiency, supporting the prosperity of its utilization as an effective adsorbent against toxic dyes from wastewater.

The Effect of Temperature and Calcium Cloride Extract on Zinc Desorption in Changed Calcareous Soils

Zinc desorption studied for ten soils was variance in calcium carbonate, clay percent, and organic matter from Duhok province in the north of Iraq involved (Bamarny, Zawita Assih, Semeel, Kanimasi-1& 2, Khanke, Zakho, Batofa, and Faydi, locations). Soil testers after air dried up ground and filtered through a 2-mm sieve was taken to know the properties of the soils, zinc forms and desorption. Results showed the soluble, available, exchangeable and zinc total alternated among (0.29 - 0.94), (0.88 - 1.64), (1.71 - 2.05), and (12.25 - 56.15) mg.kg−1 one-to-one, Zn desorption raise with the raising of Zn added to research soils, extraction concentration CaCl2 from 0.1 to 1 molarity and temperature. Higher quantity of Zn release at 298K, was found in the soil of Kanimassi-1 (31.40 - 264.81) μg. g−1 at 0.1M, 1M CaCl2 extraction respectively, it may be owing to the high value of available phosphorus, CEC and organic matter and lower quantity of available-Zn and CaCO3. But the lowest amount observed in Faydi soil (14.10-118.69) μg. g−1. The high desorption of Zn at 321K, noted in Faydi soil between (50.50 - 421.00) μg. g−1 and low amount in Semeel soil between (26.35 - 222.10) μg.g−1 at 0.1 to 1M CaCl2 extraction respectively, designated Zn released more with increasing temperature. In general low quantity of Zn releases as of all researched soils causes to the great amount of CaCO3, quality and amount of clay minerals dominant that cause raise Zn bonding also low desorption from all studied soils. The effect of CaCl2 extraction concentration to increase Zn desorption was more than the effect of temperature in all soils.

Physicochemical and mineral characteristics of soil materials developed naturally on two ∼ 50 years old coal combustion residue disposal sites in Croatia

Coal combustion has been one of the most dominant sources of energy for the last two centuries, generating tonnes of coal combustion residue (CCR). Rapid soil formation has been observed at old CCR disposal sites, altering the physiochemical and mineral properties of CCR, affecting contaminant release mechanisms and nutrient availability. Although ubiquitous, pedological properties of weathered CCR have been studied at only a small number of disposal sites. This study characterized two CCR landfills of similar age (∼50 years) using a range of parameters, including pH, total nitrogen and organic carbon content, major oxides (Al2O3, CaO, and SiO2), and macronutrients (Ca, K, Mg, P, and S), as well as textural and mineralogical data. In addition, specific surface area and cation exchange capacity were determined to assess particle properties, and 13C and 29Si NMR spectra were examined to characterize the organic matter and degree of polymerization of the coal ash glassy phase. Such comprehensive approach aimed to determine indicators of soil formation and to characterize the capacity of such landfills to retain water, nutrients, and contaminants. Both landfills displayed evidence of pedogenesis reflected in the pH decrease, formation of secondary minerals (such as ettringite, hydrotalcite, gypsum, and calcite), and changes in the C:N ratio. The Plaški landfill seems to have a better capacity to hold water, nutrients, and contaminants evident by higher clay content, CEC, and SSA values, possibly explaining why it developed more rapidly than Štrmac despite their similar age. The presence of montmorillonite in Plaški could be one of the main factors accelerating pedogenesis. 13C NMR spectra point to the unburned coal particles as the main origin of organic matter and 29Si NMR spectra showed higher depolymerization of a non-crystalline fraction in bare ash samples than in vegetated ash samples.

Study of soil chemical characteristics on citronella cultivation area in the Gayo Highlands

This research tries to identify the chemical state of the soil in the existing citronella planting area in the Gayo Highlands based on altitude, slope, and soil type. The method used in this research is the descriptive method, with data collected through field surveys and laboratory analysis. Soil samples were taken at each observation point by a purposive sampling method, which was determined based on the components forming a homogeneous land unit consisting of six (6) elevation classes, five (5) slope classes, and five (5) soil types. The results of the analysis showed that the highest value of C-organic was found at location Land Unit 6 (LU6) altitude above 1,200 meters above sea level (m asl), which was 7.29%, and the lowest value was found at location LU1 (200-400 m asl), which was 0.81%. While the highest variation of CEC values was found at locations LU6 and LU3 (600-800 m asl) with a value of 56.40 cmol kg−1, the lowest was found at locations LU1. The citronella cultivation area in the Gayo Highlands was studied based on altitude, slope, and soil type at each observation point. It is still suitable to be developed as a citronella cultivation area where the value of soil chemical characteristics found at each research location is in the low to very high criteria and the pH criteria are in the acid to slightly alkaline criteria.

Characterization and Mapping of Soil-Landscape for Site-Specific Soil Management in Ayiba Watershed, Northern Highlands of Ethiopia

The characterization of soil landscapes is becoming increasingly important for making decisions regarding site-specific agriculture systems and soil management. This study was initiated for the purpose of identifying landscape-scale spatial soil variation using a toposequence model so that site-specific fertilization could be achieved. According to the finding, the soils were shallow to very deep in depth, moderately acidic to moderately alkaline in soil reaction, nonsaline in salinity, and clay to sandy loam in texture. The soils were found very low to low levels in most soil nutrients, very low to very high levels of base saturation, and deficient in zinc but have adequate levels of iron, copper, and manganese. The soil exchange complex was mainly dominated by Ca and Mg where the order of occurrence was Ca &gt; mg &gt; K &gt; Na. The CEC values were in high to very high range. Following the field survey and soil analytical results, five main reference soil groups of the World Soil Resource Base—Leptosols (56%), Luvisols (8.5%), Fluvisols (14.4%), Vertisols (13%), and Cambisol (8.2%)—were identified and mapped. Leptosols cover the largest landmass of the watershed and mostly found at the summit and hill back slopes. On the other hand, Luvisols, Fluvisols, Vertisols, and Cambisols were found on the middle and foot slopes. According to the findings, the variation in soil source indicating that topography is the primary pedogenic element in the formation of the soil in the watershed that was under research. Therefore, having local-scale-specific soil information can assist the site-specific application of soil nutrients and amendments based on spatial variability which is tailored to the soil requirements.

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.

Assessing soil fertility influenced by land use in Moche, Gurage Zone, Ethiopia

One of the main reasons for Ethiopia’s declining agricultural production is land use change under poor soil management practices. Hence, in order to evaluate the effects of various land use types on certain soil qualities, research was done on the soils of Cheha district, Gurage zone in Ethiopia’s central highlands. Four different land use types (LUTs) (cultivated, enset, eucalyptus, and wild forest) were used for this study to assess and analyze their response to soil fertility. A total of 48 soil samples (24 undisturbed and 24 disturbed) was collected from the selected LUTs and two different soil depths (SDs) (0-20 and 20-40 cm) with three replications for the laboratory analysis. The results showed that most of the properties of soil physicochemical properties of soil were significantly affected by LUTs, SD, and the interactions. The result showed that the highest sand (43%), silt (46.5%), and clay (30.30%) fractions were observed under forest land (FL), enset farmland (ENFL), and cultivated land (CUL), respectively. Concerning the SD, higher silt (40.9%) and clay (28.3%) were found in the subsurface soils. Except for CUL, textural classes of all LUTs were loamy. The highest (1.37 g cm-3) bulk density was observed under the subsurface soils of CUL and the lowest (1.06 g cm-3) was in the surface soils of FL and ENFL. In contrast to bulk density, total porosity was highest (60.1%) under surface soils of FL and ENFL and the lowest (48.3%) value was observed under subsurface soils of CUL. The combination of two factors influenced the soil pH. The highest value (6.54) and lowermost (4.82) values were found under the surface soils of ENFL and subsoils of EUCL, respectively. Comparatively, the uppermost (7.48%) and lowermost (3.55%) values of organic matter were recorded under the surface soils of FL and subsoils of EUCL. The uppermost (0.37%) and lowermost (0.17%) values of total nitrogen were registered under surface soil and subsoils of FL and EUCL, respectively. The uppermost (22.69 mg kg-1) value of Av.P was registered under superficial soils of ENFL and the lowermost (5.02 mg kg-1) was obtained under a subsurface layer of EUCL. The uppermost (37.96 cmol(+) kg-1) and lowermost (11.90 cmol(+) kg-1) of CEC values were observed under the surface soils of FL and subsoils of EUCL. The uppermost value of exchangeable acidity (1.85 cmol(+) kg-1) was recorded under soils of EUCL. This study showed that different LUTs and SDs have substantial impacts on the status of soil fertility. Soils of FL and ENFLs were relatively more fertile. Increasing eucalyptus tree cover on arable land and intensive farming severely impacted soil fertility which may have increased soil acidity. Appropriate land use and a variety of soil fertility management practices are crucial to address soil fertility loss and acidity issues

Immobilization of Cd by mercapto-palygorskite in typical calcareous and acidic soil aggregates: Performance and differences

The microscale spatial heterogeneity and complexity of soil aggregates affect the properties and distribution of heavy metals (HMs). It has been confirmed that amendments can alter the distribution of Cd in soil aggregates. However, whether the Cd immobilization effect of amendments varies across soil aggregate levels remains unknown. In this study, soil classification and culture experiments were combined to explore the effects of mercapto-palygorskite (MEP) on Cd immobilization in soil aggregates of different particle sizes. The results showed that a 0.05–0.2% MEP application decreased soil available Cd by 53.8–71.62% and 23.49–36.71% in calcareous and acidic soils, respectively. The Cd immobilization efficiency of MEP in calcareous soil aggregates was in the following order: micro-aggregates (66.42–80.19%) > bulk soil (53.78–71.62%) > macro-aggregates (44.00–67.51%), while the efficiency in acidic soil aggregates was inconsistent. In MEP-treated calcareous soil, the percentage change in Cd speciation in micro-aggregates were higher than that in macro-aggregates, whereas there was no significant difference in Cd speciation between the four acidic soil aggregates. Mercapto-palygorskite addition in micro-aggregates of calcareous soil increased the available Fe and Mn concentrations by 20.98–47.10% and 17.98–32.66%, respectively. Mercapto-palygorskite had no effect on soil pH, EC, CEC, and DOC values, while the difference in soil properties between the four particle sizes was the main influencing factor of MEP treatments on Cd in calcareous soil. The effects of MEP on HMs varied across soil aggregates and soil types, but had strong specificity and selectivity for Cd immobilization. This study illustrates the influence of soil aggregates on Cd immobilization using MEP, which can be used to guide the remediation of Cd-contaminated calcareous and acidic soils.