Exchangeable Ca Research Articles

Response of soil and vegetation in a warm-temperate Pine forest to intensive biomass harvests, phosphorus fertilisation, and wood ash application

The objective of this study was to assess the effects of different intensities of biomass harvesting, and the possible effects of compensation methods, on forest functioning. To do so, we carried out a split-plot experiment (SW France) crossing four different intensities of biomass harvesting (Stem-Only Harvest [SOH], Aboveground Additional Harvest [AAH], Belowground Additional Harvest [BAH], and Whole-Tree Harvest [WTH]) and three compensation methods (control [C], wood ash application [A] and phosphorus fertilisation [P]). The experimental treatments were followed by the plantation of pines (Pinus pinaster). The environmental consequences of treatments on soil and vegetation were evaluated 11 years after the tree plantation.Despite their low additional biomass exports (+10 % for AAH to +34 % for WTH), the non-conventional harvest practices exported much higher quantities of nutrients than the conventional SOH technique (+145 % of exported N in WTH). Additional biomass harvests impacted the soil organic matter content, with negative effects on P-organic, soil cation exchange capacity, exchangeable Ca, and most extractible nutrients. However, tree nutritional status was improved by P-fertiliser or wood ash. We observed a positive effect of wood ash application on soil pH and nutrient content but, like additional harvests, wood ash application decreased the pool of soil organic carbon (~10 %).Overall, the experiment showed that exporting more forest biomass due to the additional harvesting of biomass had negative consequences on the ecosystem biogeochemistry. Additional harvests have impoverished the soil, and decreased the soil organic carbon content. Importantly, applying nutrients as fertiliser or wood ash did not compensate for all the negative impacts of biomass exports and the method of wood ash recycling in forests could even decrease the soil organic carbon.

Changes over the Years in Soil Chemical Properties Associated with the Cultivation of Ginseng (Panax ginseng Meyer) on Andosol Soil

The sowing-to-harvest period for the medicinal plant Ginseng (Panax ginseng Meyer) is 4–6 years. Although one of the primary soils used to cultivate ginseng in Japan is Andosol, there have been few studies of the changes in the soil’s chemical properties during the cultivation of ginseng in Andosol soil. Here, we investigated the chemical properties of Andosol soil by collecting soil samples from cultivation sites with various numbers of years of ginseng cultivation. A significant negative correlation was observed between the years of cultivation and the soil’s pH, indicating that soil acidification increased with an increasing number of years of cultivation. Similarly, exchangeable calcium (Ca) showed a significant negative correlation with the years of cultivation. The soluble aluminum (Al) concentration showed a significant positive correlation with the years of cultivation and was significantly negatively correlated with the exchangeable Ca and magnesium (Mg) contents. These results suggest that a decrease in pH due to Ca absorption by ginseng, increasing Al dissolution, and a further accelerated decrease in pH occur during the cultivation of ginseng in Andosols. The increase in soluble Al with increasing years of cultivation also affected the dynamics of essential trace elements in the soil, showing significant negative correlations with the soil’s soluble copper (Cu) and zinc (Zn) contents, indicating that the Cu and Zn contents decreased with increasing Al. Our findings indicate that in the cultivation of ginseng on Andosol soil, the soil’s soluble Al content is an essential factor in changes in the soil’s chemical properties.

Nutritional Diagnosis of the Mineral Elements in Tainong Mango Leaves during Flowering in Karst Areas

The balance of the mineral nutrition in mango leaves during the flowering period affects the flowering of mango trees and fruit production. Because the soil in karst areas has a slow and unbalanced supply rate of nutrients, mango orchards in a karst area generally have a low yield. There are few studies on the fertilization of mango orchards in karst areas, especially on the diagnosis of leaf mineral nutrition. In this study, mango orchards in the typical karst areas of Guangxi province, one of the main mango-producing areas in China, were selected from the low-yielding and medium-yielding mango orchards. Surface soil samples and leaf samples from mango orchards in full bloom were collected to test for macronutrients and micronutrients. The Diagnosis and Recommendation Integrated System (DRIS) graphical method, the DRIS method, the Modified DRIS (M-DRIS), and the Deviation from Optimum Percentage (DOP) index diagnostic methods were applied to the leaves. The results showed that the DRIS graphical analysis yielded appropriate ratios of N, P, K, Mg, S, Fe, Mn, Cu with the corresponding three elements, Ca, Zn, and B, which can be used as reference diagnostic criteria. Based on the values of the DRIS diagnostic criteria for high-yielding orchards, the critical ranges of the suitable values of the mineral nutrients in the Tainong mango leaves during flowering were determined as N (14.87–17.27 g/kg), P (0.69–0.89 g/kg), K (4.45–6.90 g/kg), Ca (9.51–16.55 g/kg), Mg (1.44–2.20 g/kg), S (0.75–1.06 g/kg), Fe (0.10–0.13 g/kg), Mn (0.61–1.02 g/kg), Cu (5.41–8.89 mg/kg), Zn (7.91–18.95 mg/kg), and B (8.38–16.23 mg/kg). The results of the DRIS, M-DRIS, and DOP index methods were analyzed to determine the order of the fertilizer requirements for the low-yielding orchards: Mg > Fe > S > Zn > B > Cu > K > N > P > Mn > Ca, and for the medium-yielding orchards: Mg > Fe > B > Zn > S > Cu > N > Mn > K > P > Ca. The soil and leaf correlation analysis showed that the soil exchangeable Ca and effective Fe were significantly negatively correlated. Leaf Ca and Fe elements had a mutually antagonistic effect, leaf Mn-rich contents inhibited the uptake of the Mg and Fe elements, and low-yielding orchards had an excess of Mn and a deficiency of Mg. We found that there is lack of the Mg and Fe, a low content of the S and B, and an excess of the Ca and Mn in the mango orchards of the Baise karst area. We suggested that the DRIS graphical method is suitable for the diagnosis of three nutrient elements, and either the DRIS or M-DRIS index method can be chosen. The present research can be used for the precise fertilization of mango orchards in karst areas to improve the yield and quality of local mango orchards.

Impact of Irrigation Practices on Soil Physicochemical Properties of Josepdam Irrigation Scheme

The importance of irrigation practice in food production cannot be over-emphasised, however irrigation practices impact soils and other environmental parameters negatively. This necessitates the need for continuous monitoring of the impacts of irrigation on soils and the general environment. A study was carried out on the Josepdam Irrigation Scheme (JIS) located in Bacita, Ilorin, Nigeria. This study was limited to the impact assessment of irrigation practices on the soil physical and chemical properties. Soil samples were collected from irrigated lands at depths 0-20, 20-80 and 80-120 cm from 8 OLs on JIS using soil auger. During each season of collection, samples were kept in polyethylene bags and transported within 24 hours to the laboratory for analyses. The samples were analysed immediately according to ISRIC-FAO procedures for pH, Cation Exchange Capacity (CEC), Exchangeable Sodium Percent (ESP), Mg2+, Ca2+, Na+ and Sodium Adsorption Ratio (SAR). The results indicated that the soil texture was sandy loam and sandy clay loam, In JIS, the pH of 7.2 at inception reduced to 4.6; SAR increased from 0.4 to 2.14 meq1/2 and CEC increased from 18 to 26 cmolkg-1. The impacts of irrigation on the soil was determined. The results of these evaluations were compared with FAO standards and past research results.

Reclamation of Saline Soil under Association between Atriplex nummularia L. and Glycophytes Plants

Phytoremediation is an efficient technique for the reclamation of salt-affected soils by growing plants. The present study aims to evaluate the intercropping of halophyte Atriplex nummularia Lindl. with naturally occurring species (Mimosa caesalpiniifolia Benth, Leucaena leucocephala (Lam.) de Wit and Azadirachta indica A. Juss.) adapted to semiarid regions as a management capable of enhancing the phytoremediation capacity of these species. A field experiment was conducted in a randomized block and contained four replicates. Species were cultivated alone and in association with A. nummularia to evaluate their potential uses in the reclamation of soils. Exchangeable Ca2+, Mg2+, Na+, and K+, as well as salinity and sodicity variables, were evaluated. The evaluations were performed at 9 and 18 months of plant growth. The results indicated that A. nummularia individualized was the treatment most efficient; with reductions of 80%, 63%, and 84% in electrical conductivity, sodium adsorption ratio, and exchangeable sodium percentage values, respectively at 18 months compared to starting of the experiment. However, the use of A. nummularia and species adapted to the semiarid in association, or even alone, promoted beneficial effects on the soil quality after the establishment of the plants.

Effects of Different Microbial Fertilizers on Growth and Rhizosphere Soil Properties of Corn in Newly Reclaimed Land.

Land reclamation may expand the supply of usable land for food security. Soil microorganisms have been considered as an amendment in immature soil to improve its quality. However, different microbial fertilizers’ effects on plant growth in immature soil have largely been unexplored. In order to evaluate the effects of different microbial fertilizers on immature soil, the soil quality and microbial community structure of corn rhizosphere soil samples under different microbial fertilizers were investigated. The results revealed a significant difference between microbial fertilizers (especially seaweed microbial fertilizer, SMF) and commercial chemical compound fertilizers in the soil properties and microbial community structure. Indeed, SMF caused a 486.21%, 23.17%, 21.08%, 38.33%, and 482.39% increase in Flavobacteriaceae, Planctomycetaceae, Chitinophagaceae, Acidobacteria_Gp3, and Mortierellaceae but a 23.82%, 18.66%, 42.36%, 29.12%, 81.97%, 42.19%, and 99.33% reduction in Cytophagales, Comamonadaceae, Rhodospirillaceae, Sinobacteaceae, Aspergillaceae, Myrmecridiaceae, and Typhulaceae, respectively; while CCF caused an 85.68% and 183.22% increase in Xanthomonadaceae and Mortierellaceae but a 31.29%, 36.02%, and 65.74% reduction in Cytophagales, Spartobacteria, and Cyphellophoraceae compared with the control based on 16S and ITS amplicon sequencing of soil microflora. Furthermore, redundancy discriminant analysis of the microbial communities and soil properties indicated that the main variables of the bacterial and fungal communities included exchangeable Ca, organic matter content, total N, and available P. Overall, the results of this study revealed significant changes under different fertilizer conditions in the microbiota and chemical properties of corn soil. Microbial fertilizers, particularly SMF and SM, can be used as a good amendment for newly reclaimed land.

Fire, Herbivores, and Vegetation Type Shape Soil Biochemistry in Sodic Patches of a Semi-Arid Savanna Ecosystem

In the Kruger National Park (KNP), the lower slopes of catenas have open patches referred to as sodic patches. Fire and herbivores are dominant mediators of vegetation in sodic patches. The effect of fire and herbivores on soil properties of sodic patches remains largely understudied. Moreover, the co-existence of trees and grasses and how they influence savanna soils is an important but poorly understood phenomenon in ecology. Therefore, the present study aimed to determine the influence of 20 years of fire, herbivores, vegetation type, and their interaction on soil biochemistry of sodic patches on the Nkuhlu exclosures in the Kruger National Park, South Africa. We found a higher main effect of fire on available phosphorus, cation exchange capacity, and soil organic matter. The presence of herbivores caused an increase in soil exchangeable cations (K+, Ca2+, Na+, and Mg2+), organic matter, cation exchange capacity, and microbial activity. Tree canopies had a higher effect on total nitrogen, exchangeable Ca and Mg, soil organic matter, and cation exchange capacity than open grassland zones. Our results indicate that changes in vegetation structure due to fire and herbivores and their secondary impact on soil properties should be taken into consideration in managing savannas. Moreover, fire and herbivores play an important role in the maintenance of vegetation type (trees and grasses) in sodic patches.

Soil Acidity Indicators for Liming in Tropical Acid Soils Cropped With Soybean Under Short- and Long-Term No-Tillage Systems

Although the movement of liming materials under no-tillage (NT) systems can intensify stratification of soil chemical properties and be deleterious to soybean growth, little is known regarding the soil acidity indicators used to predict lime requirement (LR) in Brazilian soils under NT. Thus, we hypothesize that the recommendation criteria used for predicting LR in soils under NT must be different from those adopted in soils under conventional tillage (CT), and the reference values for such liming indicators may vary according to the phase following the adoption of the NT system. The study aimed to obtain soil acidity indicators for soybean (Glycine max (L.) Merill) in tropical acid soils under no-tillage (NT) systems and their respective critical levels according to the phase of NT. Sites under NT were commercial soybean crop areas located in the Cerrado region, Brazil. Systems analyzed were NTI (NT management from 0 to 5 years—initial phase), and NTTC (NT management from 5 to 20 years—transition-consolidation phase). Soil samples were collected at the 0-5, 0-10, and 0-20 cm layers, and analyzed for chemical characteristics. Relationships between crop yield response of soybean to lime application and various soil acidity-related characteristics led to establishing soil acidiy indicators for liming in tropical acid soils under no tillage. Critical levels were approximately similar in both phases of NT for exchangeable Ca and Mg, and potential acidity, but varied greatly depending on the soil layer and phase of NT management for soil pHCaCl2, CECpH7.0, and base saturation. In general, for both phases of NT, the critical levels of soil acidity indicators were lowest for the 0-20 cm layer, moderate for the 0-10 cm layer, and highest for the 0-5 cm layer. Lime applied with incorporation in the NTTC phase kept the soil with chemical attributes more favorable for plant growth than when surface liming was employed in the NTI phase, which was verified by the soybean yield response. Our results indicate the differences on the soil acidity indexes between the top and bottom depths that would not have been realized in a soil sampling for conventional tillage. Hence, recommendation criteria for lime application considering distinct soil depths and NT systems will be helpful when making lime decisions. Further research should focus on the development of reliable methods for predicting LR according to the NT phase and consequently maximize soybean production under NT systems in Brazil.

Effects of Different Organic Fertilizers on Sweet Potato Growth and Rhizosphere Soil Properties in Newly Reclaimed Land

It is well known that soil fertility is poor in most newly reclaimed land, which has been developed as an effective way to compensate farmland occupation. In order to ameliorate the soil quality of the newly reclaimed land, this study investigated the effect of commercial organic fertilizer (COF) (0.45, 0.90, 1.35 and 1.80 kg/m2), sheep manure (SM) (0.45, 0.75, 1.05 and 1.35 kg/m2), mushroom residue (MR) (1.50, 2.25, 3.00 and 3.75 kg/m2), and chemical compound fertilizer (CCF) (0.075 kg/m2) on the growth of sweet potato, soil pH, organic matter content (OMC), available phosphate, total nitrogen, available potassium, exchangeable Ca and Mg, as well as bacterial and fungal microbial composition during 2019–2021. The results from this study indicated that the COF, SM, MR, and CCF did not significantly change the soil pH, but significantly increased the OMC, which has been regarded as the most significant soil quality parameter. This suggests that the soil amendments used in this study have great potential to improve the soil quality in newly reclaimed land. However, these soil amendments exhibited a differential effect on sweet potato biomass, nutrient elements and the microbial community of the newly reclaimed soil, which depend on the kind and concentration of organic/chemical fertilizer, the application time, as well as the plant and soil parameters. The change was also observed on the bacterial and fungal soil microbial community, which provides us with a microbial basis to understand why organic fertilizer has a great effect on soil improvement. Overall, our results suggest that soil amended with organic fertilizers has great potential for the production of sweet potato in immature soil from the new reclamation land.

Controls on riverine calcium isotope ratios during basalt weathering in the Skagafjörður watershed, Iceland

This study examines the Ca isotope (δ44/40Ca) geochemistry of Icelandic rivers with the overall aims of improving the δ44/40Ca tracer, constraining solute sources, and addressing the hypothesis that basalt weathering disproportionately regulates Earth’s long-term climate. We report Ca isotope and elemental data for mainstem rivers, tributary streams, thermal and non-thermal springs, basalt, calcite, soil, vegetation, and sediment collected from the Skagafjörður region in North Iceland. Waters and calcite were further analyzed for their carbon isotope (δ13C) composition, and we conducted experiments to characterize δ44/40Ca values of riverine colloids, the clay-size fraction (<2 µm) of soil, and exchangeable leachates obtained from soil and bedload sediment. The dataset includes analyses of travertine and coexisting water samples collected from a CO2-rich spring (Hvanná river) in South Iceland.Samples show a ∼2‰ range, with groundwater, the ultrafiltered fraction of river water, and hydrothermal calcite producing among the highest δ44/40Ca values and travertine, soil exchangeable Ca, and vegetation the lowest. Riverine δ44/40Ca values are on average ∼0.20‰ higher than those for basalt, which shows minimal isotopic variability. Mainstem glacial-fed rivers entering the Skagafjörður valley from the soil- and vegetation-free highlands have higher δ44/40Ca values than direct-runoff tributaries draining catchments to the north where pedogenesis is more pervasive. Riverine δ44/40Ca values correlate with Sr/Ca and Na/Ca ratios, as well as the saturation index of calcite (SIcal). Riverine δ13C values increase from ∼−8‰ (atmospheric) to ∼−3‰ (calcite) as SIcal values increase from highly-undersaturated to near-equilibrium. One watershed (Svartá river) shows unique trends, where riverine δ44/40Ca values and Sr/Ca ratios do not correlate, and soil exchangeable leachates produced anomalously high amounts of Ca. Clay-size fractions isolated from three horizons composing a brown andosol show slightly lower δ44/40Ca values than bulk basalt, but the values overlap with those for primary minerals. Colloids appear to have lower δ44/40Ca values than truly dissolved Ca. The proxy could be developed as a tracer for colloidal contributions to riverine dissolved loads, especially in soil-mantled catchments where the inputs appear most pronounced. Groundwater δ44/40Ca values correlate with pH, temperature, distance from the coast, and Sr/Ca ratios, all consistent with fractionation control yielding varying degrees of geochemical evolution. The combined riverine patterns largely reflect three-component mixing between basalt weathering, calcite weathering, and hydrothermal water inputs. Subsurface Ca isotope fractionation indirectly impacts riverine δ44/40Ca values by elevating the δ44/40Ca values of groundwater and hydrothermal calcite. This study highlights the significance of hydrothermal water inputs of Ca and HCO3 to Icelandic rivers, which have been previously underappreciated. Mixing calculations suggest that a maximum of ∼20% of the Ca in mainstem rivers derives from surficial basalt weathering. Small tributaries draining the flanks of the valley show the clearest signals of basalt weathering by atmospheric CO2, but these waters have much lower solute concentrations than those employed in previous attempts to estimate basalt weathering rates and parameterize the climate sensitivity of the basalt weathering feedback.

Soil chemical properties in agroforestry and cassava cropping systems in Pati, Central Java

Changes in natural land use for monoculture cropping systems may affect the soil properties over a certain period of time. In an attempt to evaluate soil chemical properties in the cassava cropping system, the research was conducted in Pati Regency, Central Java. Four land use systems were compared, i.e. monoculture cassava (cultivated for 5, 10, and 15 years) and agroforestry systems in two different slopes (i.e., 8-15% and 16-40%), with four replications. Soil samples from each location were taken at a depth of 0-20 and 21-40 cm for soil chemical analysis (pH, cation exchange capacity, organic C, total N, available P, exchangeable K, Ca, and Mg). Soils in agroforestry systems had higher pH, CEC, the content of organic C, total N, exchangeable K, Ca and Mg than in cassava cropping systems, especially on the slope of 8-15%. The soil under 15 years cassava and on the slope of 16-40% had the most degraded soil chemical properties, as reflected by the lowest content of organic C, total N, exchangeable K, and slightly lower CEC and the content of exchangeable Ca and Mg. Soil chemical properties on the slopes of 8-15% were significantly better than on the slopes of 16-40%, especially in CEC and the content of organic C, total N, exchangeable K and Mg. However, there was an unclear pattern of the available P content, which was possibly due to the application of P fertilizer in cassava cropping systems.

EFFECT OF LAND USE ON SELECTED SOIL PROPERTIES IN DIFFERENT SOIL TYPES AT HARAR GITA WATERSHED, SOUTHERN ETHIOPIA

The goal of the study was to see how different land-use systems affected soil physical and chemical properties at Dengawura and Abushura, Harar Gita sub watershed in southern Ethiopia. Ten composites of representative soil samples from two depths (0-20 and 20-40cm) were collected from four land use (enset land, forest land, grassland and Wheatfield). The analysis of variance (ANOVA) was applied to determine differences in soil parameters among land-use types. Treatment means comparison was determined using the least significant difference (LSD) at 0.05 levels of significances. The result indicated that there were significant (P &lt; 0.05) differences among the four Land use for soil characteristics. For most parameters evaluated, the most favorable soil properties were observed in the forest land, followed by Enset fields, while the least favorable soil properties were found in intensively wheat fields. Enset (enset Ventricosum) fields had higher pH, available P, Cu and Zn, exchangeable Ca and K which is attributed due to the addition of manure, whereas wheat fields had the lowest pH, available P, Cu and Zn, average K and Mg, cation exchange capacity (CEC), total N and OC. Overall, this study confirms that the use of Land use increases the status of soil fertility and adopting proper management practices of the soil commonly used in enset fields are very crucial to improve soil fertility in wheat fields.

Characterization of Soil-Plant Leaf Nutrient Elements and Key Factors Affecting Mangoes in Karst Areas of Southwest China

Baise city is one of the largest producers of mangoes, with this agricultural industry located in the karst region of Southwest China. However, calcium-rich and alkaline soils, severe soil fragmentation, and poor water and fertilizer retention capacity contribute to low mango yields and are key issues that limit the development of the mango industry in karst areas. Our study objectives were to identify the soil factors that limit mango growth and yield in the karst region of Southwest China, and to determine how these growth- and production-limiting conditions vary between landscape positions. This study analyzed the differences in soil nutrient and element contents in mango leaves, and used a Random Forest algorithm to calculate the eigenvalues of the mango leaf and soil elemental indices in the different geomorphic parts (slopes, transition zone, passes, high-yielding depressions, and low-yielding depressions) of the karst peak-cluster depressions. The key factors affecting the mango leaves and soil were screened based on the diagnostic results and the eigenvalues. The results showed that for the elemental contents of Fe, Mg, Ca, and Mn in the mango leaves in the different geomorphic parts of the karst, the peak-cluster depressions were generally deficient and varied significantly. The contents of available B (AB), soil organic matter (SOM), pH, total nitrogen, available Fe, available Mn, alkaline hydrolysis nitrogen, exchangeable Ca (Caex), exchangeable Mg, and other indices in the soils differed significantly, and AB, available Zn, and available K (AK) showed low or very low content levels. In addition, the key soil factors limiting mango yield in the karst areas were AB, fulvic acid, SOM, Fe, Mn, Caex, soil water, and AK; and the key mango leaf factors were Ca, Mn, Fe, Zn, and Mg. Consequently, the characteristics of soil water content, pH, and soil organic matter may be the main drivers affecting the differences in the mango yield and the elemental characteristics. These findings suggest that the addition of organic fertilizer could improve the quality and yield of mangoes in karst areas.

Landscape and topography effects on phosphorus fractions in Mollisols of the Argentinean Pampas

Especially in semiarid regions and for calcareous soils there is a need for better understanding of the processes involved in P cycling in soils and the development of better P fertility management to mobilize the recalcitrant P pools for crop uptake. The objective of the present study was to understand the effect of landscape, slope, soil depth and land use on P-availability in Calcareous and Sandy Plain (CP and SP, respectively) landscapes of the central Argentinean Pampas. Soil profiles were described in pits dug at top, mid and footslope positions: soils were classified according to Soil Taxonomy, and samples were taken at fixed depth (0–20, 20–40, 40–60 cm) for each slope position in agricultural soil (AG) and soil under natural vegetation (NV) for physicochemical analyses and the Hedley P-fractionation. The main differences among the landscapes were in calcium carbonate, pH, CEC, exchangeable Ca, and Ca:FeAl ratio. The largest P-fraction was HCl-P in both landscapes and in general, organic P represented about 20% of total P. The most available P-forms were higher in SP. In CP, Anion exchange membrane-P (AEM-P) was defined by organic carbon and exchangeable Ca, while this was not the case for SP. In CP, AEM-P was positively correlated to NaOH-Pi and Po and NaHCO3-Pi and Po, whereas in SP, AEM-P was positively affected by HCl-P and NaHCO3-Pi. AEM-P and NaHCO3-Pi and Po increased towards the footslope position for both CP and SP mainly at 0–20 cm, while deeper strata showed less differences. Also, NV land use showed a higher proportion of available P fractions while AG presented greater differences between slope positions than NV. The knowledge about soil characteristics, the distribution of soil P-fractions and their interaction affecting the P availability facilitates more efficient fertility management, unique to each landscape and position.

Nanoporosity and Isosteric Enthalpy of Adsorption of CH4, H2, and CO2 on Natural Chabazite and Exchanged

This paper describes the isosteric enthalpy through narrow pores at low levels of coverage through adsorption of CO2, CH4, and H2 on pores in natural chabazite exchanged with aqueous solutions of Na+, Mg2+, and Ca2+ salts at different concentrations, and with variable time and temperature of treatment. Experimental data of CO2, CH4, and H2 adsorption were treated by the Freundlich and Langmuir equations. Complementarily, the degree of interaction of these gases with these zeolites was evaluated by the evolution of isosteric enthalpy of adsorption. The exchange with Mg2+ and Na+ favors an increase in the adsorption capacity for CO2. while that of Ca2+ and Mg2+ favor adsorption through to H2 and CH4. These cations occupy sites in strategic positions S4 and S4’, which are located in the channels and nanocavities of these zeolites. The presence of Ca2+ and Mg2+ at S4 and S4′ sites causes increased adsorption into the nanocavities and on the external area of the ion-exchanged zeolites. Depending on the conditions of the exchange treatment, Ca2+ and Mg2+, and Na+ were found to be most favorable, well distributed, and accessible for CO2, CH4, and H2 adsorption.

Integrated Application of Inorganic and Organic Fertilizer Enhances Soil Organo-Mineral Associations and Nutrients in Tea Garden Soil

Soil quality is one of the main factors that affect the growth and quality of tea (Camellia sinensis L.) plantations. The formation of the organo-mineral complex is one of the critical factors that influence the evolution of soil fertility. This study used chemical analyses and spectroscopy to study the effects of inorganic and organic fertilizer on the soil nutrients and organo-mineral complex in tea garden soil. SR-FTIR analysis revealed that clay minerals were connected as nuclei with the capacity to bind carbon, and that this interaction was aided by organic fertilization. Specifically, the O-H has the quickest reaction to aliphatic-C, next by Si-O, Fe-O, and Al-O in OM70. The soil pH of organic and inorganic fertilization treatments are obviously lower than the no fertilization (CK) treatment. Furthermore, OM70 and OM100 had notably higher pH values in fertilized soil. Organic fertilization (OM70) treatment significantly increased Soil organic matter (SOM), total nitrogen (TN), available phosphorous, potassium (AP, AK), as well as the concentration of total and exchangeable Ca2+ and Mg2+ in soils when compared to no fertilization (CK) and inorganic fertilization (NPK). Together, these results can provide the scientific theoretical basis for the study on the understanding of the sequestration of SOM and confirmed the feasibility of organic fertilization in improving soil fertility and supporting organo-mineral interactions, thereby making a contribution to carbon storage in tea plantation ecosystems.

Organic–inorganic calcium lignosulfonate compounds for soil acidity amelioration

Soil acidification is a problem widely occurring worldwide, which severely threaten food security and agricultural sustainability. Calcium lignosulfonate (CaLS), a cheap and ecofriendly compound, is used for the first time to amend acid soil by utilizing its unique organic and inorganic functional moieties simultaneously. Both column leaching and incubation experiments were conducted to investigate the comparative effects of CaLS (four rates at 5, 10, 15, 20gkg-1) and compared with conventional amendments, including gypsum (5gkg-1), lignin (5gkg-1), L + G (each at 5gkg-1), and control. The soil pH, exchangeable acidity and base cations, organic carbon, and different Al fractions were determined to unravel the ameliorative performance and mechanism of the treatments. Regardless of application modes and dosages, the results demonstrated that CaLS incorporation significantly increased soil pH, exchangeable Ca2+, cation exchange capacity, and organic carbon and decreased the contents of exchangeable acidity, especially exchangeable Al3+. The ameliorative mechanism was that amendment material led to the displacement of H+ and Al3+ off soil colloids by Ca2+. These released H+ and Al3+ which complexed with lignosulfonate anions into soluble organo-Al were all quickly leached from the soil column. The CaLS addition enhanced the transformation of exchangeable Al3+ and low-to-medium organo-Al complexes into highly stable organically bound fractions and immobilized into the soil. The complexing of CaLS functional groups with Al3+ impeded Al3+ from undergoing hydrolysis to produce more H+. As an environmental-friendly material, CaLS can be a promising amendment for soil acidity and Al toxicity amelioration.

Pedogenesis and landscape evolution of Calcisols on Quaternary carbonatic sediments of Fernando de Noronha and Trindade volcanic islands, South Atlantic

Carbonate-rich soils are found in different materials, climates, and environments, and are generally characterized by alkaline pH values and high base saturation, dominated by exchangeable Ca2+. Fernando de Noronha and Trindade volcanic islands, in South Atlantic, register carbonate-rich soils on bioclastic sediments at coastal areas. This study aims to investigate the pedogenic evolution of these soils associated with landscape processes. Six profiles were described and sampled, four of which located on bioclastic sediments (PN1, PN2, PT1, and PT2), one on Quaternary fluvial sediments (PN3), and one developed on calcarenites overlying ankaratrite flows (PN4). Morphological, physical, chemical, mineralogical, micromorphological and microchemical investigations were carried out, and principal component (PCA) and statistical analyses were applied to all data. The soils were classified as Calcisols, Fluvisol, and Cambisol and the results suggest that the carbonatic parent material and local climate are the main drivers of soil genesis, subordinated by biogenic and landform processes. All profiles have high exchangeable Ca2+, base saturation, pH, CaCO3 equivalent, and total Ca content, with calcite and aragonite minerals. Pedogenic carbonates features occur in all soil, being more developed in Fernando de Noronha Calcisols, and partially dissolved in Trindade Calcisols. The contrasting landscape and climate evolution between these islands explain these differences. Hence, these insular Calcisols are products of varying pedological evolution, with Holocene paleoclimates as the main factor of differentiation. Our results indicate the adoption of “bioclástico-carbonático” sub-group for Calcisols and Fluvisols from Fernando de Noronha, proposing the inclusion of “bioclástico-chernossólico” sub-group in the Brazilian Soil Classification System.

IMETHODS OF INTENSIFICATION OF HEAT EXCHANGE IN BIOGAS REACTORS

Proposed research method intensification of heat exchange in biogas reactions using alternative energy sources. The distribution of active and passive methods of heat exchange intensification is determined. The three most effective methods of heat exchange intensification are identified: the method of flow turbulence in the adjacent areas, based on purposeful artificial creation of small dry wall zones, which is the source of additional flow turbulence; the method of flow winding inside the twisted oval tubes and at longitudinal and transverse winding of tightly packed beams and tubes; the method of controlled break-out of the boundary layer at transverse tubulars by creating turboblicators on them. It is determined that in practice the most effective is the use of combined methods of intensification. The important conditions for choosing the method of heat exchange intensification are: the amount of permissible energy costs for heat exchange intensification and the type of energy available for this energy; the task of heat exchange intensification in a particular class of equipment; the technological capacity of equipment with heat exchange intensification, availability at purchase and durability in operation of equipment; the nature of distribution, structure of thermal flows and temperature fields, in which there is a need for intensification of heat exchange. The main indicator of intensification of the heat exchange process in the equipment is found – the efficiency of the process, that is, the process should be economically profitable. From the above it appears that the intensification of heat exchange can’t be considered isolated from the necessary energy costs. The determining criterion of optimization is the efficiency of the heat exchange process at a given level of energy consumption at transfer of the working environment through the equipment. Heat exchange intensification during use of gaseous working environments is of particular importance, for which characteristic reduction of intensity of heat exchange processes and high energy consumption for removal of supports at pumping of gases is characteristic. Tasks of heat exchange intensification are usually set: to reduce the size and weight of heat exchange devices; to decrease the temperature pressure, i.e. to decrease the temperature of the walls at the given temperature of heat carrier or to increase the temperature of heat carrier at the given temperature of walls. Reduction of thickness of heat transfer wall and increase of its thermal conductivity, as well as prevention waste contamination on the wall is an obvious method of intensification of heat exchange.

Contribution of the carbonized rice husk added to the substrate in the production of vegetable seedlings

The carbonized rice husk (CRH) is an agro-industrial residue with great potential for use in mixtures with other substrates for the production of vegetable seedlings. Thus, the purpose of this study was to evaluate the effect of the addition of CRH to the commercial substrate for the production of greenhouse seedlings. The evaluated vegetables were lettuce, broccoli and mustard, cultivated in polystyrene foam (Styrofoam®) trays. Five treatments were evaluated: 100% of the commercial substrate (CS); 25% of CRH + 75% of CS; 50% of CRH + 50% of CS; 75% CRH + 25% CS; and 100% CRH, in a completely randomized design with twelve replicates. The substrates were evaluated for their physical and chemical characteristics. The morphometric evaluations were: number of leaves per plant, plant height, shoot fresh matter yield, root length, and shoot and root dry matter yield. The data were submitted to regression analysis, and the homogeneity of the variance between the experiments was confirmed by the Cochran test. With the addition of CRH to the substrate, there was an increase in total porosity and P content and a reduction in density, water holding capacity, cation exchange capacity, electrical conductivity, and N, K, S, Ca and Mg contents. The carbonized rice husk added to the commercial substrate is a viable alternative for the production of lettuce, broccoli and mustard seedlings. The quality of the vegetable seedlings was higher when there was a 25% CRH + 75% CS mixture.