Exchangeable Cations Research Articles

Influence of Nitrogen Fertilizer Application on Soil Acidification Characteristics of Tea Plantations in Karst Areas of Southwest China

Nitrogen (N) fertilizer application is one of the causes of soil acidification at tea plantations. However, the effect of N fertilizer application on the soil acidification characteristics of tea plantations with different acidities remains unclear. In this study, field experiments were conducted to investigate the effects of different nitrogen fertilizer application rates on the pH, pH buffer capacity (pHBC), exchangeable total acidity (ETA), exchangeable base cations (EBCs), and cation exchange capacity (CEC) in the topsoil of non-acidified (NA), mildly acidified (MA), and heavily acidified (HA) tea plantations. The results showed that the exchangeable Al3+ (E-Al) and CEC were HA > MA > NA in all tea plantations, whereas the EBCs and base saturation percentage (BSP) were HA < MA < NA. In the tea plantations with pH > 4.0, the pH, EBCs, and BSP showed decreasing trends with increasing N fertilizer application, whereas E-Al showed an increasing trend. In the tea plantations with pH < 4.0, the soil pH showed a small increasing trend with the increase in N fertilizer application, whereas the soil exchangeable H+ (E-H), E-Al, and CEC showed decreasing trends. Meanwhile, in the pH range of 4–6, the soil acid–base buffer curve rose sharply, and an excessive application of N fertilizer (N900) significantly reduced the pHBC. In addition, a stepwise regression analysis showed that the BSP, EBCs, and exchangeable Mg2+ (E-Mg) had significant direct effects on the soil pH, whereas the CEC and N application had significant direct effects on the soil pHBC. In conclusion, a decrease in the BSP and an increase in E-Al were the main mechanisms of acidification at tea plantations, whereas a decrease in the BSP caused by the application of N fertilizer was the main cause of exacerbated soil acidification in non-acidified tea plantations.

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 (<1.0) in acid soils (acid cations not measured) to high (>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.

Dittmarite-type magnesium phosphates for highly efficient capture of Cs+

The presence of cesium ions (Cs+) in radioactive wastewater has attracted considerable attention owing to their extreme toxic effects. Thus, there is an urgent need to develop adsorbents for Cs+ with high adsorption capacities (q). While phosphate-based adsorbents have advantages for their disposal, previous adsorbents have shown limited q because of their limited capacity for ion exchange, despite showing high theoretical q values. In this study, two dittmarite-type magnesium phosphates, KMgPO4·H2O (KMP) and NH4MgPO4·H2O (NMP), were synthesized because of their ability to contain readily exchangeable cations in their interlayers. KMP and NMP demonstrated remarkable adsorption capacities for Cs+ (qeKMP = 630 mg g−1 and qeNMP = 711 mg g−1), which were the highest among all reported adsorbents and are ∼84 % of their theoretical values. Their distribution coefficients in waters with high divalent ion concentrations were low, which limits their use for the adsorption of Cs+ from such environments. After adsorption, KMP and NMP were structurally transformed into struvite-type CsMgPO4·6H2O (CsMP), which has two different stacking structures, either cubic or hexagonal, depending on the pH of the solution. The high q values of KMP and NMP enable them to reduce the volume of radioactive waste for disposal.

The Nutrient Magnesium in Soil and Plant: A Review

Magnesium is the third most abundant structural metal in the Earth's crust and is found in many rock minerals and in seawater. In the soil, it appears in the ionic form Mg2+, in solution and as an exchangeable cation. After absorption, Mg2+ is transported from the roots to the aerial part through the interior of the plant, giving this process the name of translocation. In plants, magnesium plays a fundamental role for growth and development, participating in a series of important processes for the metabolism of the plant, such as the constitution of the chlorophyll molecule, in addition to acting as an enzymatic activator. Thus, given the importance of the magnesium nutrient, the objective of this review is to present the main aspects of this nutrient in the soil and the functions performed in plants.

Structure and reactivity assessment of dioctahedral montmorillonite during provoked variable sequential cation exchange process via XRD modelling approach

The intrinsic cation exchange capacity (CEC) of clays is a crucial characteristic that offers a tool to assess their overall chemical properties. For the confinement of industrial and radioactive waste, clays are deployed as geological barriers, hence it is important to consider how they will react under external stresses. With respect to the electronegativity rate and cation ionic potential, the impact of a series of sequential cation exchange processes with heavy metals exchangeable cations was the main emphasis of this work. Using X-ray diffraction (XRD) profile modeling to assess interlayer space (IS) deformation and highlight geochemical alteration, the structural reactivity of Na-rich montmorillonite was investigated. To determine the ideal structural characteristics defining IS configuration, the study contrasted estimated reflections produced from theoretical models with those produced experimentally from 00l reflections. Per each exchanged cation, the results showed a partial CEC saturation and a heterogeneous mixed layer structure (MLS), with heterogeneous hydration behavior continuing to exist regardless the type of exchangeable cation. The established chemical constraint had no effect on the cation hydration sphere for Co (II), Ni (II), Mg (II), Cu (II), and Zn (II) exchangeable cations. However, significant interlamellar water molecule development was observed for the Cd (II), Pb (II), and Ba (II) cations, indicating a major alteration in the discretization of the hydration states and particular hydration heterogeneities. The Cd (II), Pb (II), and Ba cations were most affected by these alterations, which resulted in a constrained and inhibited CEC performance. The theoretical decomposition of the observed XRD profiles was used to show the existence of multiple layer type populations and their stacking mode, with most of the studied samples showing a tendency toward segregated stacking configuration. Moreover, as a function of the applied stress, the CEC of the stress samples gradually dropped.

Effects of several superabsorbent polymers on soil exchangeable cations and crop growth

Owing to their excellent water absorption and water retention properties, superabsorbent polymers have become an important technology for realizing agricultural water savings. To explore the exchange pathways of exchangeable cations in soil caused by different superabsorbent polymers and their effects on crop nutrient uptake and growth, three types of superabsorbent polymers, sodium acrylate, potassium acrylate and acrylamide–sodium acrylate, were used in this project to study the effects of different dosages on crop growth, root morphology and the distributions of Na+, K+, Ca2＋ and Mg2+ in the root tips. The results were as follows: among all the treatments, the inhibition effect of the sodium acrylate superabsorbent polymer was the most obvious. Compared with CK, the biomass decreased by 70.3% (AN2), the root length and root surface area decreased by 62.7% and 61.1% respectively, plant K+ and Na+ increased by 18.5% and 2423% respectively, and Ca2+ and Mg2+ decreased by 27.6% and 18.7% respectively. Adsorption experiments with Ca2＋ and Mg2+ further proved that the superabsorbent polymers adsorbed more than 95% of the Ca2＋ and Mg2+ in the soil while releasing Na+ and K+ into the soil after swelling.

Performance and deactivation mechanism of a carbon-based solid acid catalyst in the esterification of soybean saponin acid oil

In this study, a bamboo charcoal-based solid acid catalyst (BC) was generated by one-step carbonization and sulfonation at 150 °C for 4 h in the presence of sulfuric acid. The BC was characterized by Fourier transform infrared spectrometry, elemental analysis, X-ray powder diffraction, and Brunauer-Emmet-Teller specific surface area analysis. The BC had a specific surface area of 4.54 m2/g, pore volume of 0.0142 cm3/g, and acid density of 1.476 mmol/g. Subsequently, the catalytic activity and deactivation mechanism of the BC in the esterification of soybean saponin acid oil (SAO) and methanol were investigated. The results showed that the conversion yield of esterification reached 98.28% under optimal reaction conditions (i.e., catalyst addition of 10 wt%, methanol/oil molar ratio of 10:1, temperature of 65 °C, and time of 8 h). The conversion yield decreased as reuse batches increased, and was below 80% after three batches. The loss of sulfonic acid groups from the BC occurred mainly in the first esterification batch, caused by residual sulfuric acid leaching and chemical derivatization of sulfonic acid groups. In the second to fourth esterification batches, chemical derivatization was the main reason for deactivation, where the generation of sulfonate esters and exchange of metal cations with hydrogen ions accounted for more than 75% of the chemical derivatization loss. Therefore, without impurity purification of SAO, reducing the amount of sulfonate ester generated on the catalyst was found to be essential for increasing the reuse performance of the BC and reducing the cost of biodiesel production.

The closed-loop recycling strategy of Li and Co metal ions based on aqueous Zn-air desalination battery

Nowadays, it is a global problem to recycle LiCoO2 from waste lithium-ion batteries (LIBs) due to the deficiency of high business cost and environmental pollution. Here, a novel three-channel ion recovery device based on a Zn-air desalination battery (ZADB) is proposed which can supply energy while separating Li+ and Co2+ from the recovered solution. The three-channel ZADB device consists of a Zn foil anode chamber with ZnSO4 anolyte stream, an intermediate chamber with Li+ and Co2+ recovered stream and an air cathode chamber with LiOH and Co(OH)2 catholyte stream, chambers are separated by anion exchange membrane (AEM) and cation exchange membrane (CEM) respectively. It can be described by the finite element simulation (FES) of physics field that, the Li+ and Co2+ in the recovered solution move to the cathode chamber, where the OH− are produced by absorbing O2 from the air combined with electronic in the discharge process. At the same time, the SO42− moves to the other end of the Zn foil anode chamber according to the law of charge conservation, which combined with the Zn2+ removed from the Zn foil. The results show that the recovery efficiency of the ZADB device is closely related to the discharge current density and the concentration of the recovered stream. The best recovery effect has achieved when 0.2 mol L−1 recovered solution is run for 24 h at the discharge current density of 0.2 mA cm−2. The average recovery rate is 0.275 mg min−1 with the highest recovery rate is 40.73 mg h−1, and the output energy density is 102.5 Wh Kg−1 during the experiment process. In addition, the ZADB device has the excellent long-term cycling performance and recycling stability. By comparing this device with other ion recovery methods, which provides that it is a splendid way to recycle Li+ and Co2+ from waste LIBs.

Estimation of soil and crop residue parameters using AVIRIS-NG hyperspectral data

ABSTRACT Detailed ground cover information and efficient modelling approaches are needed for estimating soil properties from hyperspectral remote sensing (HRS) data. With the objective to estimate both soil and crop residue (CR) parameters using HRS data from the airborne visible-infrared imaging spectrometer-next generation (AVIRIS-NG) sensor, soil and CR samples were collected from 101 locations in the Western Catchment of Chilika lagoon, India. Nonlinear unmixing and two chemometric models were examined for estimating basic soil properties, nutrient contents, soil and CR wetness, and masses of fresh crop residue (FCR) and dry crop residue (DCR). Both soil and CR parameters showed wide variation with FCR and DCR masses varying from 0 to 13.33 Mg ha−1 and 0 to 10.16 Mg ha−1, respectively. Soils were relatively dry with an average gravimetric water content (θg) of 14% whereas CR moisture content (θc) ranged from 2.4 to 93%. Estimated coefficient of determination (R2) values in the validation datasets varied from 0.51 for soil base saturation to 0.91 for exchangeable Mg+2 using soil spectra obtained through linear polynomial unmixing of AVIRIS-NG spectra. The R2 values were more than 0.70 for clay content, soil organic carbon (SOC), cation exchange capacity (CEC), and several exchangeable cations although the CR parameters showed lower R2 values than soil parameters. With the chemometric models calibrated, high spatial resolution maps for soil and CR parameters were generated, which offer a continuous mapping capability for such parameters. Extensive soil property data also allowed us to evaluate SOC sequestration capability of different land use systems. A critical value of 1/25 for the SOC/Clay content ratio was observed for most of our agricultural land uses and degraded landscapes showed lower SOC/Clay ratios. Thus, high spatial resolution soil and crop residue parameters may be accurately assessed for large areas with multiple land use and soil cover conditions.

Combined Utilization of Chinese Milk Vetch, Rice Straw, and Lime Reduces Soil Available Cd and Cd Accumulation in Rice Grains

Cadmium (Cd) pollution poses a growing threat to rice production in acidic paddies. In south China, a common agricultural practice involves the combined utilization of Chinese milk vetch (M) and rice straw (R). However, it is unclear how the addition of lime to these amendments affects Cd bioavailability and accumulation in soil. Control (CK), chemical fertilizer (F), Chinese milk vetch + rice straw + chemical fertilizer (MRF), and Chinese milk vetch + rice straw + chemical fertilizer + lime (MRFL) treatments were applied to develop a kind of green, efficient, and practical amendment for acidic paddies. We conducted a microplot experiment to explore Cd immobilization in paddy soil and the Cd content in rice grains with these treatments. The results showed that compared with F, the rice Cd in the MRF and MRFL treatments were significantly decreased by 51.7% and 65.2% in early rice and 23.0% and 43.3% in late rice, respectively. Both the MRF and MRFL treatments significantly reduced soil available Cd and weak acid-extractable cadmium (Aci-Cd) concentrations and increased soil organic matter (SOM), exchangeable cation concentrations, and pH, which converted Cd into a stable form in soil. In addition, the MRF and MRFL treatments increased soil pH value by reducing soil exchangeable hydrogen ion concentration (E-H). Additionally, recombination of Cd forms was the primary factor in the reduction in available Cd concentration according to partial least squares path modeling (PLS-PM) analysis. The Cd concentration of rice grains was primarily associated with soil available Cd, soil pH value, and SOM. Overall, these results provide useful data and novel insights into reducing rice grain Cd in south China.

Determination Of Exchangeability Cations (Ec), Texture And C-Organic Content In Mineral Soils and Peat

EC or can be called exchangeable cation is a nutrient cation found in the soil. This is useful for indicating the degree of alkaline saturation, which indicates that the more saturated the soil base, the more fertile the soil will be. This study aims to obtain supporting information to obtain soil conditions that show the quality of the land as a growing medium. The method used for texture analysis on this soil refers to SNI 3423.03:1994 and C-Organic content analysis refers to SNI 4720.13:1998. The cation level test was carried out using NH4OAc solution with a Microwave Plasma Atomic Emission Spectroscopy (MP-AES) instrument. This instrument has a principle, namely atomic emission which is a form of energy produced by an atom when it returns to the ground state (Ground State) of the excited state (Excitation State). The results of this cation level test with analyte concentrations of K, Ca, Na and Mg with sample code SJ2022-01826 successively 0.65; 3,59; 0.82 and 0.94. The amount of cation content in fertile soil is worth at least 6 mg / L in accordance with the provisions of the Chemical Technical Manual.

Dibasic Magnesium Hypochlorite as an Oxidant to Tune Pasting Properties of Potato Starch in One Step

Modified starches are used widely in the food industry but often have a low nutritional value, lacking minerals vital for the human body, such as magnesium. Magnesium addition to native starches has been shown to result in changes in pasting properties. However, little work has been done on the addition of magnesium and other divalent cations to highly oxidised starches. In this work, we used dibasic magnesium hypochlorite (DMH) to oxidise potato starch to an industrially relevant degree of oxidation while at the same time introducing magnesium into the starch structure. We found that magnesium incorporation changes the pasting properties of starch and increases the gelatinisation temperature significantly, possibly due to an ionic cross-linking effect. These properties resemble the properties found for heat-moisture-treated potato starches. This change in properties was found to be reversible by performing a straightforward exchange of metal cations, either from sodium to magnesium or from magnesium to sodium. We show in this work the potential of the addition of divalent cations to highly oxidised starches in modifying the rheological and pasting properties of these starches and at the same time adding possible health benefits to modified starches by introducing magnesium.

ADSORPTION PURIFICATION OF UNREFINED VEGETABLE OILS WITH BENTONITE CLAY OF ZYRYANSK DEPOSIT

Magnesium ions predominate in the exchange complex of bentonite clay from the Zyryanskoye deposit. The amount of exchange cations varies within 76–95 mmol equivalents. The main rock-forming mineral of Zyryansk bentonite is montmorillonite. The adsorption and desorption isotherm of nitrogen by bentonite clay from the Zyryanskoe deposit has the form of a hysteresis loop, which is typical for bentonite clays from other deposits and corresponds to adsorption in mesoporous solids.
 The dynamics of the content of free fatty acids ((FFA (acid number (AN)) and peroxide compounds ((PC (peroxide number (PN)) in samples of unrefined vegetable oils: sunflower oil “Sloboda” and linseed oil “Yeleya” was studied. Six months later the AN and the PN in unrefined linseed oil, and the AN in unrefined sunflower oil increased, but the numbers did not exceed the maximum permissible values. The PN in unrefined sunflower oil increased by 6.4 times and exceeded the maximum permissible values.
 Isotherms of sorption of FFA and PC by native bentonite clay (NG) of the Zyryansk deposit have been obtained. The kinetics of sorption of FFA and PC of sunflower and linseed oil has been studied. The equilibration time is 90–120 min. The optimum operation of sorption of FFA and PC has been determined (static operation with stirring for 2 h at a ratio of m(clay) : V(oil)=1 g : 40 ml.
 The maximum degree of extraction of FFA from sunflower oil by bentonite clay was 31%; from linseed – 9%. The degree of extraction of PC from sunflower oil by bentonite clay was 48%, from linseed oil – 33%.

Spatial Variation in Soil Base Saturation and Exchangeable Cations in Tropical and Subtropical China

In the last 30 years, severe soil acidification has been found in China due to acid deposition and nitrogen fertilizer overuse. Understanding the spatial pattern and vertical variations in base saturation percentage (BSP) and exchangeable cations (Ca2+, Mg2+, K+, Na+, H+ and Al3+) can directly benefit fertilization management and ecological protection. Here, 1253 soil profiles were surveyed in tropical and subtropical regions in China to investigate the spatial variations in BSP and exchangeable cations at three soil depths of 0–20 cm, 20–50 cm and 50–100 cm. The spatial distributions were interpolated by using advanced machine learning techniques. We found that the exchangeable Ca2+ (Exch. Ca), Mg2+ (Exch. Mg) and BSP were significantly higher in paddy fields and uplands than in forests and gardens, regardless of soil depth, while the exchangeable K (Exch. K) did not significantly differ between various land-use types. The Exch. Ca and BSP in Anthrosols were significantly higher than those in Ferrosols, Argosols and Cambosols in the three soil layers. The spatial prediction results indicated that exchangeable cations and BSP were generally characterized by strong heterogeneity, and the Exch. Ca, Exch. K and exchangeable H+ (Exch. H) contents and BSP declined with increasing soil depth. This study helps us understand the spatial variation in BSP and exchangeable cations in the study area and benefits fertilization management and environmental protection.

Architected Metal Selenides via Sequential Cation and Anion Exchange on Self-Organizing Nanocomposites.

Shape-preserving conversion reactions have the potential to unlock new routes for self-organization of complex three-dimensional (3D) nanomaterials with advanced functionalities. Specifically, developing such conversion routes toward shape-controlled metal selenides is of interest due to their photocatalytic properties and because these metal selenides can undergo further conversion reactions toward a wide range of other functional chemical compositions. Here, we present a strategy toward metal selenides with controllable 3D architectures using a two-step self-organization/conversion approach. First, we steer the coprecipitation of barium carbonate nanocrystals and silica into nanocomposites with controllable 3D shapes. Second, using a sequential exchange of cations and anions, we completely convert the chemical composition of the nanocrystals into cadmium selenide (CdSe) while preserving the initial shape of the nanocomposites. These architected CdSe structures can undergo further conversion reactions toward other metal selenides, which we demonstrate by developing a shape-preserving cation exchange toward silver selenide. Moreover, our conversion strategy can readily be extended to convert calcium carbonate biominerals into metal selenide semiconductors. Hence, the here-presented self-assembly/conversion strategy opens exciting possibilities toward customizable metal selenides with complex user-defined 3D shapes.

Soil quality and fertility dynamics under a continuous cassava-maize rotation in the semi-deciduous forest agro-ecological zone of Ghana

The practice of crop rotation is known to significantly influence soil nutrient dynamics, depending on the type of rotation and the crops involved. As such, a field study was conducted to find out the effect of continuous cassava-maize rotation, where mineral fertilizer was only applied to the maize crop, on soil nutrients dynamics and soil quality thereof under varying rotation periods. The study revealed that Soil Organic Matter (SOM) and levels of soil nutrients, such as total nitrogen, available phosphorus and exchangeable cations (potassium, calcium, magnesium, and sodium) significantly declined with rotation period. Long term maize–cassava rotation led to subsoil (20–50cm) acidification. Soil quality as measured by Carbon Management Index (CMI) on the different aged rotations decreased with age, with the longest rotation period giving the least quality. These results and observations imply that long term cassava-maize rotation reduced soil quality and the resilience of the cropping system for continuous sustainable crops production. A regression analysis of soil nutrients with CMI under the continuous cassava-maize rotation identified the crucial role of soil total N (r2 = 0.56) and exchangeable K (r2 = 0.44) in sustaining productive cassava-maize rotation system and improved soil quality within the semi-deciduous forest agro-ecological zone. It is thus, recommended that enhanced and targeted organic and inorganic fertilization regime could be deployed on the cassava-maize rotation system to improve the inherently low levels of nutrients and increase crop yields.

Drivers of tree demographic processes in forest fragments of the Brazilian Atlantic forest

In heterogeneous landscapes, such as the Brazilian Atlantic Forest, forest fragments are likely to undergo highly uncertain successional pathways because anthropogenic and environmental factors strongly affect demographic processes such as recruitment, growth, and mortality. We used data from 134 permanent plots (0.01–0.10 ha) across seven forest fragments in Minas Gerais, Brazil, to assess how anthropogenic variables and environmental factors drive demographic processes in Atlantic forest fragments. For each plot, we quantified anthropogenic variables related to land-use history (LUH) and estimated levels of fragmentation based on forest cover, forest fragment size, and distance to the forest edge. We also measured environmental factors related to topography (i.e., elevation and slope), soil chemical characteristics (i.e., soil pH in H2O, exchangeable cations, P content and soil organic matter), and climate (i.e., average annual precipitation and climatic water deficit [CWD]). We used plot basal area (BA) as a proxy for forest age. We quantified the effect of anthropogenic and environmental factors on relative recruitment, growth, and mortality rates using linear mixed-effects models (LMM). We found that anthropogenic variables (LUH and BA) were stronger predictors of relative recruitment (p-value < 0.001) than environmental variables. For relative growth, soil, elevation, and BA (p-value < 0.001) have the strongest effect. CWD (p-value < 0.001) was the most important predictor for mortality, suggesting that dry periods increase mortality rates in the studied fragments. Our findings suggest that the land-use history of individual fragments, combined with a higher frequency of drought events leading to increased mortality and turnover of individuals, will increase differences in demographic processes and successional pathways among fragments, thereby increasing the heterogeneity of these fragmented landscapes.

INFLUENCE OF TEAK (Tectona grandis) LINN ON SOIL NUTRIENTS STATUS IN AKANGA TEAK PLANTATION, NASARAWA STATE, NIGERIA

Teak species have been found to have effects on soil properties different from those of indigenous natural forests in terms of organic matter accumulation and soil properties on the forest floor. This research aims at evaluating the physico-chemical properties of soil under Teak plantations in Akanga Teak plantations, Nigeria. Soils were sampled and analyzed based on procedures described by Bouyoucos, Day, and Reeuwijk. Based on the results, soil particle size from the plantation had the highest percent of sand (74.5±1.1). There was a fluctuation of soil pH between the age series, 1981 age series had the highest pH (6.2±0.0) in both seasons. The nitrogen content had a steady declined as the plant age increased, while the organic matter and phosphorus content increased with the age of the plant species in the area. There was a decline in soil nutrients during the wet season, which also coincided with the active growth period of forest trees. Thus, it is evident from this study that monoculture plantation of exotic species may lead to an initial reduction of soil organic content and nutrient elements in the soil; then a gradual buildup of soil organic matter and exchangeable cations with age.

English

The aim of this study is to evaluate the effect of biochar on tomato production under controlled conditions. Trials were installed using a complete randomized block design (CRD) with 5 replications of 4 treatments: T0 (0%); T1 (8%); T2 (12%) and T3 (16%). During plant growth, parameters including height, diameter, number of leaves, number of fruits and plant biomass were collected. Plants obtained from pot that received biochar (T1, T2 and T3) were higher than plant without biochar application (T0). The average value of tomato fruits per treatment indicated that plants from treatment T1 displayed a greater number of fruit per plant with an average of 12&plusmn;2; whereas plants in control treatment, T0 did not have fruit. Plants from treatments T2 and T3 showed a number of fruit between control and T1. Soil chemical analysis indicated that exchangeable cation, CEC, pH, SOM, total nitrogen and C/N ratio were higher than in the initial soil. Regarding microbial activity, various treatments did not have a significant effect on soil enzymic activity. The recovery of waste as a source of organic materials is a practice to be encouraged in urban horticulture and in open field to restore soil fertility. Key words: Biochar, soil quality, tomato, yield.

Influence of the Valence of Iron on the NO Reduction by CO over Cu-Fe-Mordenite

A comprehensive study of the catalytic properties of the copper-iron binary system supported on mordenite, depending on the iron valence—CuFe2MOR and CuFe3MOR—was carried out, and redox ability has been considered as a decisive factor in determining catalytic efficiency. Acidity was studied by TPD-NH3, DRIFT-OH, and DRT methods. The total acidity of both samples was high. The Brönsted acidity is similar for both bimetallic samples and is explained by the acidity of zeolite; Lewis acidity varies greatly and depends on the exchange cations. A screening DRIFT study of CO and NO has shown redox capacity and demonstrated a potential for using these materials as catalysts for ambient protection. CuFe2MOR demonstrated stable Cu and Fe species, while CuFe3MOR showed redox dynamic species. As expected, CuFe3MOR displayed higher catalytic performance in NO reduction via CO oxidation, because of the easily reduced intermediate NO-complex adsorbed on the metallic Cu and Fe sites, which were observed through in situ DRIFT study.