Acid Exchange Research Articles

Morphological Characters and Soil Characteristics of Potential Horticultural Plants Growing in the Wild

This study investigated the variations observed in morphology of four (4) potential horticultural plants: Callichilia stenosepala Stapf, Clerodendrum splendens G. Don, Combretum bracteatum Herb. Madr. ex Wall and Combretum indicum (L.) Defillips and the soil characteristics of their habitats. Plants samples were obtained within University of Uyo Main Campus, Use Offot village in Uyo Local Government Area and Ifiayong Usuk Village in Uruan L.G.A. of Akwa Ibom State. Soil samples were obtained around the base of the studied plants before collection. Plants' morphological characters were extensively described and the soil samples analyzed using standard methods. The results revealed that these plants thrive on slightly acidic soils (6.31±0.07 to 6.75±0.05). Soils supporting Callichila stenosepala recorded the highest electrical conductivity (18.2±4.10), organic carbon (5.28±0.80), total nitrogen (4.86±0.52), calcium (164.00±10.20), magnesium (74.36±6.21) and exchange acidity (2.88±0.07) values, soils supporting Clerodendrum splendens recorded the highest pH (6.75±0.05), bulk density (1.88±0.004), phosphorus (2.08±0.003), sodium (18.40±4.09), potassium (32.18±7.02) and clay (34.00±6.10). Also, Combretum indicum was supported by soils having higher sand (62.00±7.10) and silt (23.00±4.30) contents while Combretum bracteatum occurred on soils with lower values of base cations, basic nutrient elements and soil physical properties. In conclusion, there are plants with potential horticultural values found within the study area and there are significant differences in the soil properties at the locations in which they are found. A better ecological investigation is needed in order to provide useful insights needed for the adoption, management, mass production, and better utilization of these potential horticultural plants within the study area.

ВИКОРИСТАННЯ БІОЧАРУ І МІСКАНТУСУ ГІГАНТСЬКОГО (MISCANTHUS GIGANTEUS) ДЛЯ РЕМЕДІАЦІЇ ҐРУНТУ, ЗАБРУДНЕНОГО НАФТОПРОДУКТАМИ

The dynamics of changes in the chemical composition of soils contaminated with oil products during the vegetation of Miscanthus giganteus, as well as under the conditions of adding biochar (biochar) were studied. The possibility of using the culture of Miscanthus giant and biochar for soil remediation under conditions of oil pollution was analyzed. It was shown that the introduction of biochar into the soil enriched it with nitrate nitrogen, which was actively assimilated by giant miscanthus plants during the growing season. The absorption of nitrate anions by plants was especially active in the second series of the experiment, when the soil + biochar was contaminated with diesel fuel. It was established that the content of NH4+ ions in both series of the experiment increased until the end of the growing season. Obviously, ammonium nitrogen is absorbed to a lesser extent by M. giganteus plants, compared to nitrate. The increase in ammonium content can be additionally caused by the activity of soil microbes in the rhizosphere of plants, which contributes to the accumulation of ammonium nitrogen in the soil. It has been shown that miscanthus plants actively absorbed water-soluble forms of phosphorus, especially in the period from June to September. The application of biochar was a significant source of phosphorus, although its release into the soil is a rather slow process. It was determined that additional amounts of potassium were added to the soil with biochar, which was actively used by the M. giganteus culture. The minimum amounts of potassium in both series of studies were absorbed by plants of E groups, where the content of diesel fuel in the soil was the highest. The introduction of petroleum products had a minor effect on the value of exchangeable acidity. The addition of biochar contributed to the shift of the acid-base balance in the direction of alkalinity, but after the end of the miscanthus vegetation (September), a decrease in the pH of the saline extract of the soil was noted. It is shown that the most noticeable decrease in the concentration of diesel fuel in the soil was noted under the conditions of adding biochar and after growing miscanthus, which can be effectively used for the remediation of lands contaminated by oil products.

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

Enumeration of synergistic relationship between carbon dioxide evaluation and nutrient budget during vermicomposting of cereal grain processing industry sludge

Despite the growing concerns about global warming issues, very little emphasis is being given to understand the dynamics of CO2 emission in a vermicomposting system. The present study was designed to investigate the synergistic relationship between nutrient budget and CO2 evaluation rate during the vermistabilization of cereal grain processing industry sludge employing Perionyx excavatus. The results obtained from Principal Component Analysis and correlation studies revealed a negative correlation among both variables indicating that a periodical increase in nutrient budget decreases the CO2 evaluation rate during vermicomposting. The vermicomposting treatment containing 5 % Cow dung was deemed superior in terms of physico-chemical, maturity, phytotoxicity as well as nutritional parameters (pH, Conductivity, Total organic carbon, exchangeable acidity, heavy metal content, BOD, COD, NPK). Finally, statistical interpretation coupled with apropos analysis was employed to conclude that enriching the raw materials prior to any vermicomposting practice is key to reducing the emission of CO2.

The Application of Coffee Pulp Biochar Improves the Physical, Chemical, and Biological Characteristics of Soil for Coffee Cultivation

A field experiment was conducted for 2 years (2019 and 2020) to determine the response to the application of Biochar (BC) obtained from the coffee pulp in combination with chemical fertilization (CF) in coffee trees. The established treatments were the edaphic application of different doses of BC (0, 4, 8, and 16 t ha−1) and levels of CF (0, 33, 66, and 100% of the nutritional requirements) on the physical (bulk density (ρa), stable aggregates), chemical (nutrient availability), and biological (respiration) properties of soil from a coffee crop. Regarding the physical properties, it was mainly observed that BC doses of 8 or 16 t ha−1 reduced ρa (0.82 and 0.83 g cm−3, respectively) and increased the aggregation status (96.5% and 96.84%, respectively) in comparison to 0 t ha−1 in 2020. The chemical properties showed that the application of 16 t ha−1 BC decreased about 60% of the exchangeable acidity (EA) compared to the control (0 t ha−1) whereas the pH (4.96 and 4.92) and organic carbon (OC) (4.41 and 4.59) were higher than in the control soil (EA: 0.58 and 0.54 meq/100 g; pH: 4.63 and 4.55; OC: 4.17 and 4.32% in 2019 and 2020, respectively). Soil respiration (biological property) strongly increased (around 50–60%) with the combination of 66% CF and BC doses between 8 and 16 t ha−1 in both years. Doses between 8 and 16 t ha−1 BC of the coffee pulp can improve the quality of soils for coffee cultivation and provide an alternative and more sustainable amendment that may help reduce chemical fertilization.

Calculating soil titratable acidity from routine soil analyses of cultivated South African soils using various model structures

Soil titratable acidity (TA) is determined through extraction with an acetate-buffered salt solution (potassium sulphate, K2SO4) and is routinely used to predict the soil lime requirement using the Eksteen method. Soil TA is not always reported by commercial soil testing laboratories, but rather exchangeable acidity (1M KCl) is determined. Therefore, a need exists to use other routinely determined soil properties in a model to derive TA. In this study, routine soil-analysis results from a commercial laboratory (n = 5 915 measurements) were used to generate various model structures to calculate a theoretical value of TA and to evaluate the accuracy thereof. Measured TA was found to be significantly correlated to the calculated TA using the Eksteen R-value, soil pH, organic carbon percentage, exchangeable Ca2+ and Mg2+, and a function of the interaction between pH and organic carbon. Soil TA could be calculated most accurately using these factors in multivariate adaptive regression splines model (r 2 = 0.69, mean absolute error = 0.16) at TA values of < 2 cmolc kg−1. However, the exponential model calculations remained stable over a larger range of actual TA values up to 4 cmolc kg−1. Given the ease of use and interpretability, it is recommended that an exponential function model is used to calculate TA.

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.

Characterization and classification of rice-growing soils on Imo clay shale residua in Eastern Nigeria and current suitability for rice production: I. Omasi-Agu and Omor agrarian communities

The soils on Imo clay shale residua at Omasi-Agu and Omor areas in Anambra State, Nigeria were sampled in order to characterize classify and evaluate their current suitability for rice production following standard scientific procedures. The soils generally belong to loamy textural classes or finer, especially in the subsoil layers. The morphological and physical properties of soils showed that the soils were poorly drained favouring high water retentivity due to low hydraulic conductivity and slow permeability. All these soil conditions support good rice performance. Though the soils at Omasi-Agu contained high levels of exchangeable bases, exchangeable acidity was equally high leading to low base saturation of &lt; 35% but at Omor the base saturation was &gt; 35%. Thus, the soils were, respectively, classified as Typic Kandiaquults (Soil Taxonomy) correlated with Gleyic Cambisols of the World Reference Base for Soil Resources (WRBSR) and Typic Kandiaqualfs (Soil Taxonomy) correlated with Gleyic Cambisols (WRBSR). Even though the soils of Omor appeared to be generally more fertile than Omasi-Agu soils, both have similar constraints to rice production, that is, insufficiency of nutrients (f) and possibility of erosion by flooding (e) in limited areas (&lt; 25%). Therefore, the current suitability of the soils for rice production is suitability class 2 with fertility constraints (S2fe). For sustainable rice production, supplementary addition of nutrients especially P2O5 from triple superphosphate and some minor levelling and bunding are required to control erosion due to flooding in the limited areas.

Characterization and classification of rice-growing soils on Imo clay shale residua in Eastern Nigeria and current suitability for rice production: II. Anaku and Igbariam communities.

The soils on Imo Clay Shale residua were sampled at Anaku and Igbariam in Anambra state, Nigeria to characterize, classify and evaluate their current suitability for rice production following standard scientific procedures. After several auger borings, modal profiles were sited, dug, described, and sampled. The soils generally belong to loamy textural classes or finer, especially in the subsoil layers. The morphological and physical properties of soils showed that the soils were poorly drained, favouring high water retention due to low hydraulic conductivity and slow permeability. All these conditions favour good rice performance. Though the soils contained high levels of exchangeable bases, exchangeable acidity was equally high leading to low base saturation (&lt; 35%). Thus, the soils were classified as Typic Kanhaplaquults (Soil Taxonomy) and correlated to Gleyic Cambisols (World Reference Base for Soil Resources). Due to fertility inadequacies, the current suit- ability unit of the soils for rice production is suitability class 2 with fertility constraints (S2f). This implies that for sustainable rice production supplementary nutrients especially P2O5 from triple superphosphate or rock phosphate need to be applied. Based on the soil chemical results the following recommendations were made for optimum rice production: 100.00-120.00 kg ha‒1 urea, 60.00 kg ha‒1 P2O5 from triple superphosphate and 15.00 kg ha‒1 K2O (muriate of potash).

Cation Exchange Properties of Subsurface Soil in Mid-Subtropical China: Variations, Correlation with Soil-Forming Factors, and Prediction

Soil cation exchange property (SCEP) is important in soil development and environmental buffering. However, the variations in SCEP and its correlation with soil-forming factors in subsurface soil are not fully understood. In this study, we quantified the surface and subsurface SCEP variations as a function of parent material, vegetation, hillslope position, and soil type. Fifty upland soil profiles from mid-subtropical China were selected. The cation exchange capacity (CEC) and effective CEC (ECEC) of subsurface soil were significantly higher in soils derived from slate, Quaternary red clay (QRC), and limestone than in soils derived from granite and sandstone. The subsurface soils derived from limestone had the highest base saturation (BS) and the sum of base cations, and the lowest aluminum (Al) saturation. The SCEP in surface soil significantly varied with vegetation and hillslope position. The surface soil CEC was the highest in mixed-forest vegetation, whereas the ECEC and exchangeable acidity (EA) were the highest in arable vegetation. Exchangeable potassium (K+) was lowest and the EA was highest in soil orders at the strong development phase. Exchangeable calcium (Ca2+), magnesium (Mg2+), CEC, and BS were the highest in soil orders at the intermediate development phase. The prediction accuracy of soil CEC using the random forest model was higher than that obtained using multiple stepwise regression, with the best results (R2 = 0.92) obtained in the surface soil. Our study indicated that the SCEP in surface and subsurface soils was controlled by different soil-forming factors and could be effectively predicted by soil properties in subtropical China.

Effect of lime rates and method of application on soil properties of acidic Luvisols and wheat (Triticum aestivum, L.) yields in northwest Ethiopia

Soil acidity has become a major constraint that threatens sustainable agricultural production in Ethiopia. This study was conducted to evaluate effects of lime rates and application methods on selected soil properties and wheat (Triticum aestivum, L.) yields on acidic Luvisols of northwestern Ethiopia. The treatments included control, 0.5, 1, 2 and 3 t ha−1 lime drilled along the seed rows and 2, 3, 6 and 12 t ha−1 lime applied in broadcasting method. The experiment was arranged in a randomized complete block design (RCBD) with three replications. Lime rates applied for this experiment were quantified using exchangeable acidity and Buffer pH methods. To analyze selected soil properties, composite soil samples were collected immediately before sowing and after harvest. Results revealed that liming significantly increased soil pH, available phosphorus, and exchangeable bases but markedly reduced exchangeable Al3+ contents. The lime rates determined by buffer pH method were greater in ameliorating soil acidity, increasing soil nutrients status and crop yields than exchangeable acidity. Besides, lime application along the row was better in overcoming soil acidity constraints and increasing crop yields compared to broadcast application. Application of 12 t ha−1 lime in the broadcasting method, 3 t ha−1 and 2 t ha−1 lime drilling along the row increased wheat grain yield by 65.10, 49.80 and 27.05%, respectively, compared to the control. Likewise, partial budget analysis showed that the highest net benefit (51,537 Birr ha−1) was obtained from plots amended with 3 t ha−1 lime while the lowest economic profit (31,627.5 Birr ha−1) was recorded from treatments that received 12 t ha−1 lime. Thus, we concluded that application of 3 t ha−1 lime in row is a promising practice to mitigate soil acidity and increase available nutrients, exchangeable bases and crop yields in the study area and similar soil types elsewhere.

Agrochemical Parameters of the Fertility of the Arable Meadows Differentiated Soils of the Primorsky Region in the Conditions of Long-Term Agricultural Use

The results of studies of the agrochemical properties of meadow differentiated soils of reference plots that have been in agricultural circulation for a long period are presented. The humus content, exchange acidity and the degree of saturation with bases have not changed much over 35 years of intensive soil use in agriculture. A decrease of hydrolytic acidity and the content of available phosphorus, as well as a significant increase in the content of exchangeable potassium was revealed. A trend towards a decrease in the content of exchange bases was noted. The calculated complex indicator of the agrochemical state of the soil indicates the multidirectional change in soil fertility in the studied areas, which is associated with differences in the availability of mobile forms of phosphorus and humus. The need for the widespread application of phosphorus fertilizers and a decrease in the differentiation of soil fertility in various areas has been identified.

Chemical and Biological Response of Four Soil Types to Lime Application: An Incubation Study

The soils of four citrus orchards in western Zhejiang were studied in this research. In order to explore the effects of lime on soil chemical properties and bacterial communities, the incubation experiment was conducted with six different dosages of lime addition, 0, 0.6, 1.2, 2.4, 4.8, 7.2 g/kg, respectively. The results showed that soil pH increased significantly (p &lt; 0.05) and the contents of exchangeable acid decreased significantly (p &lt; 0.05) at the early stage of lime application. As time went by, the reacidification existed in the soil of each treatment, mainly reflected in a significant (p &lt; 0.05) decrease in soil pH. Liming increased the nitrate nitrogen content and decreased the ammonium nitrogen content in the four soils. However, the responses of other nutrient indexes to lime varied in different soils, which might be due to the different degrees of soil acidification. In general, the addition of lime increased the soil integrated fertility index (IFI) and improved the soil nutrient status. The application of lime under 2.4 g/kg significantly improved the structure of bacterial community and increased the relative abundance of soil bacterial community species, while the application of lime above 4.8 g/kg might inhibit the growth and activity of microorganisms, resulting in the reduction of soil microbial biomass and diversity. Redundancy analysis (RDA) showed that lime affected the bacterial community mainly by reducing the content of soil active acid and exchangeable acid. At the same time, network analysis showed that the bacterial community had a stronger buffer capacity against external disturbances after lime application. In conclusion, the addition of lime with appropriate amount (2.4~4.8 g/kg, corresponding to a field application rate of 5.8~11.5 t/ha) in acid orchard soil could improve soil properties, soil integrated fertility, and the diversity and stability of the bacterial community.

Long-Term Successive Seasonal Application of Rice Straw-Derived Biochar Improves the Acidity and Fertility of Red Soil in Southern China

Soil acidity is a crop production problem of increasing concern in acid red soil. The potential of biochar as a soil amendment/for soil acid management in agricultural fields is a recently recognized yet underutilized technology. Related evidence is currently limited to short-term indoor experiments with one-time BC applications and no crop cultivation, yet the degree to which soil acidity may be impacted by the biochar aging process on long-time scale remains unclear. To evaluate the effects of successive seasonal applications of rice straw-derived biochar (BC) on acidity and fertility of soil, a five-year outdoor column trial was conducted using wheat-millet rotated acidic upland soils from the south of China. BC was applied to the top 0–15 cm of soil at the rates of 0 (BC0), 2.25 (BCL), and 22.5 (BCM) Mg ha−1 with an identical dose of NPK fertilizers at the beginning of each crop season. Our results showed that the wheat-millet biomass yield gradually decreased over five rotation cycles in BC0 without BC application. In contrast, after five rotations, BCM led to an increase in the total wheat/millet grain yield by 138%, and the straw yield increased by 253% compared to the control. The cumulative above-ground nutrient uptake of P, K, Ca, Na, and Mg in BCM also increased by 139%, 171%, 129%, 182%, and 71%, respectively, compared to that in the control. This positive effect was attributed to the increase in soil pH (3.29 units), cation exchange capacity (5.66 cmol kg−1), soil available P (241%), K (513%), Ca (245%), Mg (265%), exchange base (3.36 cmol kg−1), base saturation percentage (65.7%), and decrease in the exchangeable acidity, especially exchangeable Al3+ content (&lt;0.1 cmol kg−1). Our results demonstrated that rice straw-derived BC application to soil at 22.5 t ha−1 was found to be highly consistent in decreasing soil acidity and reducing soluble and exchangeable Al3+, indicating its higher ameliorating capacity in the south of China in the long run.

A Highly Active, Long-Lived Oxygen Evolution Electrocatalyst Derived from Open-Framework Iridates.

The acidic oxygen evolution reaction underpins several important electrical-to-chemical energy conversions, and this energy-intensive process relies industrially on iridium-based electrocatalysts. Here, phase-selective synthesis of metastable strontium iridates with open-framework structure and their unexpected transformation into a highly active, ultrastable oxygen evolution nano-electrocatalyst are presented. This transformation involves two major steps: Sr2+ /H+ ion exchange in acid and in situ structural rearrangement under electrocatalysis conditions. Unlike its dense perovskite-structured polymorphs, the open-framework iridates have the ability to undergo rapid proton exchange in acid without framework amorphization. The resulting protonated iridates further reconstruct into ultrasmall, surface-hydroxylated, (200) crystal plane-oriented rutile nanocatalyst, instead of the common amorphous IrOx Hy phase, during acidic oxygen evolution. Such microstructural characteristics are found to benefit both the oxidation of hydroxyls and the formation of OO bonds in electrocatalytic cycle. As a result, the open-framework iridate derived nanocatalyst gives a comparable catalytic activity to the most active iridium-based oxygen evolution electrocatalysts in acid, and retains its catalytic activity for more than 1000h.

English

In Rwanda, the traditional fired solid bricks embody high fuel consumption and quantity of clay during their molding. Traditional solid bricks are also heavy compared to perforated bricks. This study aimed at investigating the performance of perforated clay bricks made of clay soil (CS) mixed with charcoal waste (CW) as an additive. The physical, chemical and mechanical properties of CS mixed with 0, 10, 30, 40 and 50% of CW were determined. The bricks were extruded manually with the inclusion of a varied number of perforations: 4, 8, 12 and 15 number perforations. The chemical analysis included the determination of organic carbon, exchangeable acidity and chemical components (through XRD) in the soil matrix. The chemical analysis depicted an increase in CaO proportions with an increase in charcoal waste content. There was also an increase in the amounts of exchangeable cations. The research found that with an increase in perforations, weight loss is reduced. However, non-perforated bricks depicted the least abrasion resistance, followed by bricks with 4 perforations. As the CW content increased from 0 to 50%, bricks with 15 and 12 perforations displayed the highest abrasion resistance. The research concludes that an increase in charcoal waste led to an increase in the linear shrinkage of clay soil bricks due to increased calcium cations and reduced magnesium cations in the soil. An optimum of 30% of charcoal waste was identified for the linear shrinkage of clay soil bricks. Bricks having 12 perforations and below with 30% charcoal waste additive can be categorized as category I (load-bearing) bricks.

Relationship of Physiographic Position to Physicochemical Characteristics of Soils of the Flooded-Savannah Agroecosystem, Colombia

Savannah floodplains are a natural agroecosystem located in the eastern plains of Colombia, with soils considered to be of low fertility. This assumption has not been rigorously validated by direct experimental studies. The aim of the study was to analyze the soils’ physicochemical characteristics of the “banks” and “lows”, which are physiographic positions, from the floodplain savannah in Arauca, Colombia. Soil samples were collected in “low” (n = 14) and “bank” (n = 15) physiographic positions. For each soil sample, the following chemical variables were determined: pH, organic carbon (OC), total nitrogen (TN), P, K, Ca, Mg, Na, exchange acidity, cation-exchange capacity (CEC), Fe, Cu, Mn, Zn and B, and physical variable (texture). The Wilcoxon non-parametric test (Mann–Whitney) was applied for the comparison of the soil’s physicochemical variables in each physiographic position (p &lt; 0.05). The highest values for each variable analyzed correspond to the physiographic position of “low” (p &lt; 0.05). The pH, T.N., Na, K and B were not statistically significant (p &gt; 0.05). The physiographic positions of “bank” and “low” of floodplain savannah presented low levels of most nutrients, with slightly higher values in the “low” physiographic position. Corrective measures must be applied to improve the nutritional values of savannah soils and, consequently, the productivity of native forages. Despite these deficiencies, the vegetation cover is given by very well-adapted native grasses, reflecting the conditions of said agroecosystem.

Co-Application of Inorganic Fertilizers with Charcoal and Sago Bark Ash to Improve Soil Nitrogen Availability, Uptake, Use Efficiency, and Dry Matter Production of Sorghum Cultivated on Acid Soils

Efficient management of N fertilizers enhances crop yields and contributes to sustainable food security. Tropical acidic soils with high Al and Fe are prone to easy loss of basic cations, such as NH4+, via leaching and erosion. Appropriate soil amendments and agronomic practices minimize the loss of fertilizer nutrients, improve soil nutrient retention, and maximize their uptake by plants. This study aimed to evaluate the effects of co-applying charcoal and sago bark ash with inorganic fertilizers on N availability, uptake, use efficiency, and dry matter production of sorghum in a tropical acid soil. The results revealed that the co-application of inorganic fertilizers with charcoal and sago bark ash increased sorghum plant height, dry matter production, N uptake and N use efficiency. The soil treated with a combination of 100% of the recommended rate of charcoal and sago bark ash (C1A1) resulted in significantly higher sorghum dry matter production, N uptake, and use efficiency compared with normal fertilization (U1). The C1A1 treatment resulted in significantly lower soil available N compared with U1. The C1A1 treatment enhanced the uptake of N by the sorghum plants, resulting in less available N in the soil after the experiment. Although the effects of co-applying charcoal and sago bark ash on soil total N were not glaring, this practice increased soil pH and total C, and reduced exchangeable acidity and Al3+. A long-term field study is recommended to confirm the effects of co-applying inorganic fertilizers with charcoal and sago bark ash on sorghum productivity, economic viability, and soil nutrient residual effects.

Dynamics of Acidity Component of the Soils as Influenced by Liming in Upper Brahmaputra Valley Zone of Assam, India

An incubation study was conducted to investigate the effect of lime (CaCO3 )on the acidity components in Upper Brahmaputra Valley Zone (UBVZ) of Assam. Fourteen(14) geo-referenced soil samples were collected from Sibsagar and Jorhat districts of Assam. Soils were treated with 3 different doses of lime viz. 10 per cent Lime Requirement (LR10), 25 per cent Lime Requirement (LR25) and 50 per cent of Lime Requirement (LR50) and initial properties were recorded before liming. Samples were incubated in laboratory at different period of time viz. 15, 30, 60 and 90 days after liming (DAL) with moisture content at Field Capacity (0.33 bar). At four different intervals, soils were analysed for soil acidity components viz. total acidity, exchange acidity, exchangeable Al3+ and exchangeable H+. The soil of Upper Brahmaputra Valley Zone (UBVZ) of Assam were highly acidic to moderately acidic, sandy loam to silt loam in texture with high OC content ranged from 0.72 to 2.59%. The Cation Exchange Capacity (CEC) value ranged from 7.8 to 14.2 cmol (p+)/ kg. Application of lime brought about mark decreased in acidity components viz. total acidity, exchange acidity, exchangeable aluminium and exchangeable hydrogen. Soil acidity components recorded highest decreased at 90 DAL @ LR50 and decreased started from 15 days onwards. The findings of the investigation showed that liming @ LR10 was found effective in reducing soil acidity. The residual effect of lime was found persisting till 90 days. However, the magnitude of lime was increasing with increase in application of lime@ from LR10 to LR25 and to LR50.

COMPARATIVE ANALYSIS OF Tectona grandis AND Acacia auriculiformis EFFECTS ON THE TOPSOIL PROPERTIES IN A RAINFOREST ECOSYSTEM OF SOUTHERN NIGERIA

The study investigated the effects of teak and acacia plantations on topsoil properties in a rainforest ecosystem of Southern Nigeria. The study established ten 10m x 10m quadrats in each plantation and the natural forest which was the control. Ten soil samples were gotten in each plantation Laboratory analysis was done on particle size composition, porosity, water holding capacity, pH, organic C, N, P, K, Ca, Mg, Na, Pb, Cd, Zn, Cu, Mn, and Fe. Results showed that the exchangeable acidity was very high in soils under acacia with mean value of 1.03 cmolkg-1. The concentrations of Ca, Organic C and N were higher in soils under teak and acacia plantations than the natural forest. Moreover, the exchangeable acidity was very high in soils under acacia (1.03 cmolkg-1). The concentrations of Pb, Cd, Cu and Zn were higher in soils under plantation than the natural forest. The study recommended that mulching of soil should be encouraged and the periodic monitoring of the soil fertility status should be done as the plantations grow older.