Exchangeable Ca Research Articles

Organic/inorganic phosphorus partition and transformation in long-term paddy cultivation in the Pearl River Delta, China

Identification and quantification of different soil phosphorus (P) fractions level are important for improving agricultural productivity and developing sustainable management practices in these agricultural soils under long-term cultivation. However, few studies have been conducted to investigate P fractions level and their transformation in these soils. This study was conducted to characterize P fractions as affected by different paddy cultivation ages (200, 400-yr and 900-yr) among soils of the Pearl River Delta Plain in China. A sequential chemical fractionation scheme and 31P nuclear magnetic resonance spectroscopy (31P NMR) were employed to quantify various P fractions and speciation. Results showed soil easily-labile P, moderately-labile P and non-labile P had a positive relationship with total P (TP) and available P (AP). Analysis with 31P NMR spectroscopy revealed that inorganic P including orthophosphate (Ortho-P) and pyrophosphate (Pyro-P) increased with cultivation age, while organic species monoester phosphate (Mono-P) and diester phosphate (Diester-P) decreased. Moreover, acid phosphatase (AcP), neutral phosphatase (NeP), exchangeable Ca and sand contents are the main factors that affected the transformation of soil P composition, and non-labile P (Dil.HCl-Pi) and Pyro-P had significant contribution to soil P availability by affecting P activation coefficient. Therefore, long-term paddy cultivation, influenced by these soil parameters including NeP, AcP, exchangeable Ca and sand, accelerated the transformation of soil organic P/non-labile P to inorganic P.

Soil potassium adsorption at several shallot center areas, Brebes Regency, Central Java Province

Brebes Regency, Central Java, is one of Indonesia's most important shallot production center implementing intensive agriculture. In the bulb production, K is needed more than other nutrients. This study aimed to assess and describe the adsorption characteristics of K on the soils of the shallot farming system in Brebes District, Central Java. Soil samples were collected at several locations in the shallot center areas of Brebes Regency, Central Java Province. The observed soil properties included pH H<sub>2</sub>O, EC, soil texture, organic C, potential-K, exchangeable Ca, Mg, Na, and K, CEC, exchangeable Al and H, and water-soluble K. K adsorption was simulated by the Freundlich equation. The proportion of K from low to high of retention energy in the soil studied had the order, namely water-soluble K<exchangeable K<potential-K. The K adsorption result showed that the soil had a high capacity to adsorb K. It indicated that added K was accumulated in the soil. The high capacity to adsorb K indicated that K accumulated in Brebes with continuous K fertilization. This research recommended that to increase the efficiency of K fertilizer, it is necessary to introduce the technology to mine K in Brebes soils like bacteria capable of dissolving K or biofertilizers.

Characterization of Rice Growing Soils of Lower Brahmaputra Valley Zone (LBVZ) of Assam, India

An experiment was conducted to characterize and classify the physico-chemical properties of different rice growing soils namely Ahu, Sali and Boro rice of Boko block of Assam. A total of sixty (60) geo-referenced and representative (0-15 cm) samples of soil were collected from the three different rice growing soils (20 each) viz., Ahu, Sali and Boro. The soils were then tested for their different physico-chemical properties. Soil textural classes varied from sandy loam to clay loam for Ahu and Sali rice while clay loam in Boro rice with strongly acidic to moderately acidic in their reactions (pH 4.52 to 5.85). Soil organic carbon was found to be medium to high in Ahu and Sali rice but high in Boro rice growing soils. The clay content was found to be significantly more in Boro rice growing soils as a contrary to Ahu and Sali rice growing soils. The EC values represented the non-saline nature of the soils and the CEC of all the rice growing soils of Boko block was invariably low with the mean values of 8.66 cmol (p+) kg-1 for Ahu rice growing soils, 8.80 cmol (p+) kg -1 for Sali rice growing soils and for Boro rice growing soils it was 8.90 cmol (p+) kg-1. All the available primary nutrients were medium in their status except available phosphorus which was low to medium. Exchangeable Ca2+ was the dominant basic cation followed by Mg2+.

Phosphorus-Enriched Organomineral Fertilizers Affect the Cation Exchange Algorithm of the Soil: A Comparative Evaluation

The aim of this study is to determine the effects of phosphorus-enriched cattle manure applications on the exchangeable cations content, cation exchange capacity (CEC), and base saturation rate (BSR) of the lime soil. The research was carried out with four different levels (except control) of dairy cattle manure (M1: 10; M2: 20; M3: 30; M4: 40 t ha-1) and with four different levels (except control) of phosphorus dose (P1: 10; P2: 20; P3: 30; P4: 40 kg P ha-1) in the ecological conditions of Southwest Türkiye during the wheat vegetation period of 2019-2021. The study was carried out in medium calcareous soil (14.8%) with three replications randomized blocks experimental by composing organomineral fertilizer combinations. According to the results of the study, the highest change in exchangeable Ca and K content in soils was obtained from organomineral fertilizer applications by 11.2% and 29.7% respectively, and the highest change in exchangeable Mg and Na content was obtained from dairy cattle manure applications by 25.1% and 18.2%, respectively for M4P2 (40 t ha-1 dairy cattle manure + 20 kg P ha-1). Among the fertilization systems, the highest increase in total exchangeable cations was 13.1% and the increase in CEC was 21.3% in organomineral fertilizer applications. The fastest decrease in the BSR was also obtained from the organomineral fertilization system. As a result, it has been determined that M4P2 application is the most economical and the most effective combination in the cation exchange capacity among organomineral fertilizer combinations.

Red mud with enhanced dealkalization performance by supercritical water technology for efficient SO2 capture

The total de-alkalization treatment of industrial solid waste red mud (RM) has been a worldwide challenge. Removing the insoluble structural alkali fraction from RM is the key to enhancing the sustainable utilization of RM resources. In this paper, supercritical water (SCW) and leaching agents were used for the first time to de-alkalize the Bayer RM and to remove sulfur dioxide (SO2) from flue gas with the de-alkalized RM slurry. The results showed that the optimum alkali removal and Fe leaching rates of RM-CaO-SW slurry were 97.90 ± 0.88% and 82.70 ± 0.95%, respectively. Results confirmed that the SCW technique accelerated the disruption of (Al–O) and (Si–O) bonds and the structural disintegration of aluminosilicate minerals, facilitating the conversion of insoluble structural alkalis to soluble chemical alkalis. The exchangeable Ca2+ displaced Na+ in the remaining insoluble base, producing soluble sodium salts or alkalis. CaO consumed SiO2, which was tightly bound to Fe2O3 in RM, and released Fe2O3, which promoted Fe leaching. RM-SCW showed the best desulfurization performance, which maintained 88.99 ± 0.0020% at 450 min, followed by RM-CaO-SW (450 min, 60.75 ± 6.00%) and RM (180 min, 88.52% ± 0.00068). The neutralization of alkaline components, the redox of metal oxides, and the liquid-phase catalytic oxidation of Fe contributed to the excellent desulfurization performance of the RM-SCW slurry. A promising approach shown in this study is beneficial to RM waste use, SO2 pollution control, and sustainable growth of the aluminum industry.

Clarithromycin as soil and environmental pollutant: Adsorption-desorption processes and influence of pH

Antibiotics pollution is a growing environmental issue, as high amounts of these compounds are found in soil, water and sediments. This work studies the adsorption/desorption of the macrolide antibiotic clarithromycin (CLA) for 17 agricultural soils with different edaphic characteristics. The research was carried out using batch-type experiments, with an additional assessment of the specific influence of pH for 6 of the soils. The results show that CLA adsorption reaches between 26 and 95%. In addition, the fit of the experimental data to adsorption models provided values between 1.9 and 19.7 Ln μmol1−n kg−1 for the KF, Freundlich affinity coefficient, and between 2.5 and 10.5 L kg−1 for Kd, distribution constant of Linear model. Regarding the linearity index, n, it varied between 0.56 and 1.34. Desorption showed lower scores than adsorption, with an average of 20%, and with values of 3.1 and 93.0 Ln μmol1−n kg−1 for KF(des) and 4.4 and 95.0 L kg−1 for Kd(des). The edaphic characteristics with the highest influence on adsorption were the silt fraction content and the exchangeable Ca content, while in the case of desorption, they were the total nitrogen, organic carbon, and exchangeable Ca and Mg contents. Regarding the pH, within the range studied (between 3 and 10), its value did not decisively affect the adsorption/desorption process. Overall, the set of these results could be of help to program appropriate measures leading to the retention/elimination of this antibiotic when it reaches the environment as a pollutant.

Soil calcium prompts organic carbon accumulation after decadal saline-water irrigation in the Taklamakan desert

Soil organic carbon (SOC), as a crucial measure of soil quality, is typically low in arid regions due to salinization, which is a global issue. How soil organic carbon changes with salinization is not a simple concept, as high salinity simultaneously affects plant inputs and microbial decomposition, which exert opposite effects on SOC accumulation. Meanwhile, salinization could affect SOC by altering soil Ca2+ (a salt component), which stabilizes organic matter via cation bridging, but this process is often overlooked. Here, we aimed to explore i) how soil organic carbon changes with salinization induced by saline-water irrigation and ii) which process drives soil organic carbon content with salinization, plant inputs, microbial decomposition, or soil Ca2+ level. To this end, we assessed SOC content, plant inputs represented by aboveground biomass, microbial decomposition revealed by extracellular enzyme activity, and soil Ca2+ along a salinity gradient (0.60–31.09 g kg−1) in the Taklamakan Desert. We found that, in contrast to our prediction, SOC in the topsoil (0–20 cm) increased with soil salinity, but it did not change with the aboveground biomass of the dominant species (Haloxylon ammodendron) or the activity of three carbon-cycling relevant enzymes (β-glucosidase, cellulosidase, and N-acetyl-beta-glucosaminidase) along the salinity gradient. Instead, SOC changed positively with soil exchangeable Ca2+, which increased linearly with salinity. These results suggest that soil organic carbon accumulation could be driven by increases in soil exchangeable Ca2+ under salinization in salt-adapted ecosystems. Our study provides empirical evidence for the beneficial impact of soil Ca2+ on organic carbon accumulation in the field under salinization, which is apparent and should not be disregarded. In addition, the management of soil carbon sequestration in salt-affected areas should be taken into account by adjusting the soil exchangeable Ca2+ level.

Soil Chemical Properties as Affected by Tillage Method, Phosphorus and Lime Application

Continuous land degradation and soil acidity are some of the major causes of below optimal crop yields in Kenya. Sustainable crop production therefore calls for efficient soil health management strategies. Field experiments were carried out at Waruhiu Farmers Training Centre, Kiambu for two seasons to evaluate the effects of tillage methods, phosphorus and lime application on selected properties of acid soils. Ploughing, strip tillage and hand hoe tillage methods and, DAP + lime (DAPL), TSP + lime (LP), TSP (P) were evaluated. Burnt lime at 3.2 tones ha-1 rate was used as lime source while 52kg P ha-1 was used as Phosphorus source. Obtained data indicated that the soils were strongly acidic with high exchangeable Al3+ and Al saturation, low cation Exchange capacity (CEC) and available P. Combination of Ploughing, lime and phosphorus in form of TSP significantly (P ≤ 0.05) led to > 38% increase of soil pH, >75% extractable P, 51% exchangeable Ca, >60% CEC, 54% Exchangeable Mg and reduced Al concentrations by >83% compared to the control. Similarly, combination of ploughing, DAP and lime significantly (P ≤ 0.05) increased CEC by 42% and available P by 81% compared to control. DAPL was observed to significantly (P ≤ 0.05) promote higher levels of exchangeable Al Compared to control and LP in both seasons. Plough DAPL also increased available P by 49% compared to strip DAPL. Strip LP significantly increased Exchangeable Ca by 46% compared to control. Sole tillage methods did not significantly affect soil properties. It can, be concluded that integrating ploughing with either DAPL or LP improves the selected acid soil properties. There is however need for long term studies to understand long term effects of the fertilizer- lime -tillage methods interaction on soil acidity management.

Effects of cyanobacteria on soil properties in forest and cultivated lands of Madhupur tract

A laboratory experiment was conducted at the Department of Soil Science of Bangladesh Agricultural University, Mymensingh to assess the effect of cyanobacteria on soil properties of cultivated and forest lands of Madhupur Tract. The population of cyanobacteria in two soils from Madhupur and one fromfrom BAU farm was counted followed by their identification up to genera level by fluorescence microscope. A marked variation was observed in cyanobacterial population among the soils: 27.8x105 g-1 in BAU farm soil, 2.70x105 g-1 in Madhupur cultivated soil and 1.62x105 g-1 in Madhupur forest soil. A total of 21 isolates were identified from all the soils taking eight isolates from each of Madhupur cultivated and BAU farm soils, and five from Madhupur forest soil . Of the 21 isolates, six isolates taking two from each soil were inoculated into all the three soils to see their effect on soil properties. These were Fischerella Mc and Aulosira Mc from Madhurpur cultivated soil; Calothrix Mf and Scytonema Mf from Madhurpur forest soil; Anabaena Bf and Nostoc Bf from BAU farm soil. The results reveal that there was an increase of soil pH, organic matter, total N, available P, exchangeable Ca, available S and CEC and a decrease in exchangeable K and exchangeable Na concentrations. The impact of different isolates on most of the soil properties was significant except their effect on exchangeable K for all soils, exchangeable Na for BAU farm soil and CEC for Madhurpur cultivated soil. Usually isolates showed better performance in their native soils than in other soils and cyanobacteria inoculation showed a positive indication towards improving fertility of soils. Bangladesh J. Agri. 2023, 48(1): 112-122

Hydrogeochemical characteristic and recognization of saline groundwater formation and evolution in silty coast of the Yellow Sea and Bohai Sea, Eastern China

Saline groundwater is a valuable unconventional water resource in silty coastal zone, which contain complex and fragile sedimentary and hydrological environments that are widely distributed and vulnerable to human activities. Coastal groundwater salinization along the eastern coast of China since the late Pleistocene is thought to be a response to global environmental change. Previous studies have shown a spatial and temporal link between the development of saline groundwater and deposition of marine strata. However, groundwater salinization is becoming an increasing problem in coastal zone, and the hydrogeochemical characteristics and cause of the groundwater salinization or desalinization remain poorly understood. In this study, we compared the hydrogeochemical characteristics and relationships between saline groundwater and the sedimentary environment in two representative, muddy coastal zone of the Yellow Sea coast (YSC) and Bohai Sea coast (BSC). Our monitoring results show that the groundwater varies from fresh water, to brackish water, saltwater, and brine moving offshore of the BSC, with total dissolved solid (TDS) concentrations of 203–184,196 mg/L. In contrast, brine is absent from the YSC, where the TDS concentrations range from 280 to 41,690 mg/L. The relationships between δ2H and δ18O values indicate that freshwater–seawater–brine and freshwater–seawater mixing are the main processes leading to enrichment in TDS in the BSC and YSC, respectively. Based on the relationship between the major cations, Cl−, and Cl/Br ratios, the results show that the groundwater salinity is primarily due to saltwater intrusion and secondly to water–rock interactions (i.e., evaporitic salt dissolution and cation exchange). The regression curves on plots of Na–Cl and (Ca+Mg)–(CO3+SO4) have negative slopes (−0.33 and −0.34, respectively) for the groundwater samples from the BSC and YSC, indicating the Na in groundwater exchange for Ca due to seawater or residual seawater intrusion. The saline groundwater (or brine) samples with reverse ion exchange indicate that seawater or residual seawater has invaded the aquifer, and in which Na+ is replacing Ca2+ and Mg2+. These results enhance our understanding of the formation and evolution of saline groundwater, and provide insights into groundwaters in other silty coastal zones.

Competition and site weakly explain tree growth variability in undisturbed Central African moist forests

Abstract Identifying and quantifying factors that influence tree growth are crucial issues to ensure sustainable forest management, particularly in moist tropical forests. Tree growth depends on several factors comprising ontogenic stage, competition by neighbours and environmental conditions. Several studies have focused on one or two of them, but very few have considered all three, especially in Central Africa. We investigated the effects of diameter and competition on tree growth, in four Central African sites characterized by their soil physicochemical properties, at both tree community and population levels. We calibrated growth models using diameter data collected on 29,741 trees between 2015 and 2018, on twelve 4 or 9‐ha plots spread over the four sites. These models included diameter, wood density, competition indices and site effect as explainable variables at the community level and excluded wood density at the population level. At the community level, the best models explained 11% of growth variability with a decreasing effect of species wood density, diameter, site and competition. Our results show that even if low, site effect can result from different soil nutrients depending on both tree size and species wood density. We observed higher tree growth on sites with (i) high exchangeable K, organic C, total N and total P for low wood density species; (ii) high available P and C:N for small trees, high exchangeable Ca and Mg for medium to large trees, all belonging to medium and hard wood density species. At the population level, the best models explained between 0 to 43% of growth variability, with significant competition effect (resp. site effect) for 21 (resp. 9) of the 43 species studied. Site ranking varied greatly between the 9 species concerned, probably reflecting different sensitivities to the scarcity of particular soil nutrients. Synthesis. Our study provides original results on the factors influencing tree growth in Central Africa, showing that the potential effect of soil nutrients depends on tree size and species wood density. Remaining highly unpredictable at the population level, this effect makes it essential to increase the number of dynamics monitoring systems in logging concessions.

Comparison of Soil pH and Exchangeable Cation Quantification by Various Wet Methods with Near- and Mid-Infrared Spectroscopy Prediction

ABSTRACT Rapid soil analyses can be obtained by infrared (IR) spectroscopy, but few studies have evaluated the suitability of different reference wet chemical methods to calibrate models predicting soil fertility. The aim of this study was to assess the accuracy of IR spectral-based models for the determination of soil pH measured in water, potassium chloride (KCl), and calcium chloride (CaCl2), and exchangeable basic cation content measured by the ammonium acetate (NH4OAc, 1 M and 0.02 M variations, pH = 7), Mehlich-III, Ambic-I, citric acid (1%), compulsive exchange, and Bray-II methods. Near- to mid-infrared (NIR, MIR) spectral-based models predicting soil pH and exchangeable cations measures were calibrated by partial least squares regression for a set of soils containing highly and intermediately weathered clay minerals and variable sesquioxide contents. The ratio of root mean square error of prediction (RMESP) to analyte component range was compared to a threshold value for contextual model accuracy assessment. pH measurements in CaCl2 matrices led to better calibrations and predictions of soil pH by IR spectral models compared to pH measurements in water and KCl matrices. Exchangeable calcium (Ca) and magnesium (Mg) concentrations determined by compulsive exchange and the NH4OAc (1 M, pH = 7) extraction methods, respectively, were most accurately predicted by NIR spectral-based models (RMSEP = 1.2–1.4 and 0.37 cmolc kg−1, respectively). The ratio of performance to inter-quartile distance (RPIQ) is recommended as an alternative figure of merit to traditionally reported ratio of performance to deviation (RPD) for IR spectral-based models predicting soil chemical properties. Subsetting soil samples by similarities in physiochemical properties improved the accuracy of soil pH and exchangeable Ca content predictions.

The impact of irrigation with treated wastewaters on soil and kikuyu grass nutrient compositions.

A lysimeter study was conducted for 1 year to examine how the source of wastewater for irrigation impacted soil physicochemical properties and kikuyu grass (Pennisetum clandestinum) nutrient composition. The wastewater used included treated wastewater produced by a membrane bioreactor (MBR) and intermittently decanted aerated lagoon (IDAL) treatment systems. No significant differences were observed between the treatments regarding total nitrogen and total phosphorus across the depths of the columns. However, highly significant differences were observed for Na content of the soils at various depths. Remarkable differences were recorded for soil exchangeable K and Na at different depths. In contrast, soil exchangeable Ca and Mg experienced no significant differences concerning the depth of the columns. For kikuyu grass, sodium contents of the grasses irrigated with MBR and IDAL treated wastewaters increased more than 200% and 100%, respectively, when compared with the grass irrigated with tap water. Over the period of monitoring considered in this study, there was no sign of excessive soil salinity/sodicity issues. The MBR treated wastewater has the potential to supply the grass with a constant dosage of valuable nutrients such as N and P without the requirement of using chemical fertilizers. This reduces the risk of contamination of receiving waters and groundwater and enhances the recycling of the nutrients in the wastewater to achieve a circular economy of nutrients. PRACTITIONER POINTS: Application of treated wastewaters revealed no harmful effects on soil and plant nutritional properties over the study period. The membrane bioreactor (MBR) treated wastewater potentially supplies the grass with constant dosage of valuable nutrients in the absence of chemical fertilisers. Sodium contents of the grasses irrigated with MBR and IDAL treated wastewaters increased more than 200% and 100%, respectively. Soil soluble and exchangeable cations showed very similar trends of changes versus the depth of the soil over the study period.

Effects of Long-Term Application of Cl-Containing Fertilizers on Chloride Content and Acidification in Brown Soil

Chloride is a necessary micronutrient for plant growth, and with long-term application of chlorine-containing fertilizer, significant amounts of Cl− are introduced into farmland ecosystems. Many recent studies have focused on chlorinated fertilizers’ effects on crop yield and quality, while few studies have examined their effects on soil properties. To determine the effects of the long-term application of chlorinated fertilizer on soil Cl− ions and soil acidification, we conducted a 35 year long-term study of chlorine-containing fertilizer in a peanut–corn rotation (since 1984). We chose three of eight experimental treatments: (1) no fertilization (CK), (2) urea + monoammonium phosphate + potassium chloride (lower Cl), and (3) urea + ammonium chlorophosphite + potassium chloride (higher Cl). We measured the Cl− concentrations, pH, cation exchange capacity (CEC), exchangeable H+ and Al3+, and exchangeable alkali ions (K+, Na+, Ca2+, and Mg2+) at different soil depths (0–20, 20–40, and 40–60 cm). Compared to CK, chlorine-containing fertilizer application significantly increased the content of Cl− in the soil profile. Compared to the control, the Cl− content of lower Cl treatment of 0–20, 20–40, and 40–60 cm soil layers increased 11.08, 9.01, 15.21 mg kg−1 respectively, and the higher Cl treatment increased 38.71, 34.71, 32.05 mg kg−1 respectively. Compared to CK, chlorine-containing fertilizer application significantly reduced the soil pH by 0.41, 0.17, and 0.25 and 1.25, 0.91, and 0.88, respectively, in the 0–20, 20–40, and 40–60 cm soil layers. The higher chlorine treatment significantly increased the exchangeable Al3+ content in the 0–20, 20–40, and 40–60 cm soil layers by 2.79, 1.64, and 0.94 mg kg−1, respectively, significantly increasing the risk of aluminum toxicity. Furthermore, the soil exchangeable Ca2+ and Mg2+ contents and soil base saturation were significantly reduced. Although the Cl− content in the high-chlorine-treated soil was far from endangering crop growth, it accelerates soil acidification and the loss of base ions and increases the risk of Al3+ toxicity, which will not only affect the topsoil, but also the subsoil. Therefore, the long-term application of high content chloride fertilizers should be avoided in agricultural production.

Impact of Elevation Change on the Physicochemical Properties of Forest Soil in South Omo Zone, Southern Ethiopia

The assessment of the distribution of soil physicochemical properties provides basic information for our understanding of the soils to grow crops and sustain forests and grasslands. The changes in soil physicochemical properties along elevational gradients were studied in a less accessible Sida Forest, southern Ethiopia. Hence, the present study was conducted to assess the distribution of soil physicochemical properties along the elevational gradients and to evaluate the fertility status of the soil. Data on soil physicochemical properties were collected from five points (four from each corner and one from the center) of the main plot. A pit of 20 cm × 20 cm was dug at a depth of 0–30 cm and a kilogram of composite soil samples was brought to the Wolkite Soil Testing Laboratory for physicochemical analysis. The results revealed that the physicochemical properties of the collected soil samples show a significant correlation with elevation changes. Sand had a significantly negative correlation and variation with elevation; it decreases as elevation increases with the rate of correlation (r = −0.44 ∗ ∗ , P ≤ 0.001 ). However, silt had a nonsignificantly positive (r = 0.20, P < 0.079 ) correlation to the elevation, while clay had a significantly positive correlation to elevation, and it increases as elevation increases with the rate of correlation coefficient (r = 0.40 ∗ ∗ , P ≤ 0.001 ). Soil OC, OM, TN, CEC, and exchangeable Mg2+ had significant positive correlation to the elevation; they increase as elevation increases with the rate of correlation coefficient (r = 0.42 ∗ ∗ , P ≤ 0.001 ), (r = 0.41 ∗ ∗ , P ≤ 0.001 ), (r = 0.44 ∗ ∗ , P ≤ 0.001 ), (r = 0.34 ∗ ∗ , P < 0.002 ), and (r = 0.27 ∗ , P < 0.014 ), respectively. While BD, pH, EC, Av. P, exchangeable Ca2+, and exchangeable K+ had a nonsignificant negative correlation to the elevation, they decrease as elevation increases with the rate of correlation (r = −0.70 ∗ ∗ , P < 0.134 ), (r = −0.20, P < 0.075 ), (r = −0.05, P < 0.683 ), (r = −0.04, P < 0.701 ), (r = −0.04, P < 0.693 ), and (r = −0.053, P < 0.693 ), respectively. This study attempted to provide information on the impact of elevation on soil’s physicochemical properties. Given that, the soil’s physicochemical properties exhibit variation with elevation changes.

Soil quality index as a tool to assess biochars soil quality improvement in a heavy metal-contaminated soil.

The assessment of soil quality improvement provided by biochars is complex and rarely examined. In this work, soil quality indices (SQIs) were produced to evaluate coffee industry feedstock biochars improvement on soil quality samples of a heavy metal-multicontaminated soil. Therefore, a 90-day incubation experiment was carried out with the following treatments: contaminated soil (CT), contaminated soil with pH raised to 7.0 (CaCO3), contaminated soil + 5% (m/m) coffee ground biochar, and contaminated soil + 5% (m/m) coffee parchment biochar (PCM). After incubation, chemical and biological attributes were analyzed, and the data were subjected to principal component analysis and Pearson correlation to obtain a minimum dataset (MDS), which explain the majority of the variance of the data. The MDS-selected attributes were dehydrogenase and protease activity, exchangeable Ca content, phytoavailable content of Cu, and organic carbon, which composed the SQI. The resulting SQI ranged from 0.50 to 0.56, with the highest SQI obtained for the PCM treatment and the lowest for the CT. The phytoavailable content Cu was the determining factor for differentiating PCM from the other treatments, which was a biochar original attribute and helped to improve soil quality based on the SQI evaluation, further than heavy metal immobilization due to the soil sample pH increase. Longer-term experiments may illustrate clearer advantages of using biochar to improve heavy metal-contaminated soil quality, as physical attributes may also respond, and more significant contributions to biological attributes could be obtained as biochar ages.

Prediction of some selected soil properties using the Hungarian Mid-infrared spectral library

Routine soil chemical and physical laboratory analysis provides a better understanding of the soil by evaluating its quality and functions. Demands for the development of national Mid-infrared (MIR) spectral libraries for predicting soil attributes with high accuracy have risen substantially in the recent past. Such MIR spectral library is usually regarded as a fast, cheap and non-destructive technique for estimating soil properties compared to laboratory soil analysis. The main objective of this research was to assess the performance of the Hungarian MIR spectral library in estimating four soil properties namely: Cation Exchange Capacity (CEC), Exchangeable Mg and Ca and pH water at different scenarios. Archived soil samples were scanned and spectra data were saved in the Fourier transform infrared spectrometer OPUS software. Preprocessed filtering, outlier detection and calibration sample selection methods were applied to the spectral library. MIR calibration models were built for soil attributes using partial least square regression method and the models were validated with sample predictions. R2, RMSE and RPD were used to assess the goodness of calibration and validation models. MIR spectral library had the ability to estimate soil properties such as CEC and exchangeable Ca and Mg through various scale models (national, county and soil type). The findings showed that the Hungarian MIR spectral library for estimation of soil properties has the ability to provide good information on national, county and soil type scales at different levels of accuracy.

Effects of liming on soil respiration and its sensitivity to temperature in Cunninghamia lanceolata plantations.

The primary distribution area of acid deposition coincides with areas of Chinese fir (Cunninghamia lanceolata) plantations. Liming is an effective method of restoring acidified soil. To understand the effects of liming on soil respiration and temperature sensitivity within the context of acid deposition, we measured soil respiration and its components in Chinese fir plantations for one year beginning in June 2020, with 0, 1 and 5 t·hm-2 calcium oxide being added in 2018. The results showed that liming considerably increased soil pH and exchangeable Ca2+ concentration, and that there was no significant difference among different levels of lime application. Soil respiration rate and components in the Chinese fir plantations exhibited seasonal variations, with the highest values during the summer and the lowest values during the winter. Although liming did not alter seasonal dynamics, it strongly inhibited heterotrophic respiration rate and increased autotrophic respiration rate of soil, with minor effect on total soil respiration. The monthly dynamics of soil respiration and temperature were largely consistent. There was a clear exponential relationship between soil respiration and soil temperature. Liming increased temperature sensitivity Q10 of soil respiration and autotrophic respiration but reduced that of soil heterotrophic respiration. In conclusion, liming promoted soil autotrophic respiration and strongly inhibited soil heterotrophic respiration in Chinese fir plantations, which would facilitate soil carbon sequestration.

Soil compaction in skid trails still affects topsoil recovery 28 years after logging in Central Amazonia

The use of heavy machinery in logging operations leads to soil compaction, especially in highly used skid trails. In Amazonia, recovery of topsoil physical properties has been reported in skid trails. So, the present study sought to determine if this was a full recovery by investigating additional attributes, such as soil chemical properties and fine root biomass (FRB). In addition, forest floor litter was investigated to present a more complete view of soil recovery dynamics. To accomplish this, litter above sampling locations was collected, as well as soil samples below this in two depths. These depths represented the recovered topsoil layer (0–5 cm) and the still compacted soil layer (5–10 cm) below. Three areas were compared: control, middle of the skid trails, and skid trail ruts. Dry mass, C%, N% were determined for litter and FRB. Foliar nutrients (P, K, Ca, Mg, Fe, Zn, Mn) were also determined. Soil chemical properties such as pH, cation exchange capacity, base saturation, aluminum saturation, soil organic C and nutrients (total N, available P, exchangeable Ca, Mg, K, Na, Fe, Zn, Mn) were also assessed. The primary objective was to determine if there was a full recovery of properties evaluated in the topsoil, but also to determine if the compacted soil below acted as an effective hardpan that potentially exerted influence on the recovered topsoil. In the skid trail ruts, results revealed no significant differences with the controls in the recovered topsoil for FRB and all but one soil nutrient, Mn which was elevated. Additionally, the base saturation and volumetric water content of the ruts topsoil was significantly higher than the controls indicating a potential hardpan condition below. So, even though a topsoil may be considered fully recovered, the compacted soil below may still exert influence in the form of increased soil moisture and nutrient accumulation. Therefore, the key finding of this research is that for the first time a recovered topsoil in skid trails was demonstrated to be affected and influenced by the compacted soil below. This influence in the very clayey soils of Amazonia was observed after nearly-three decades.

Effect of Deforestation on the Status of Soil Fertility

In Ethiopia, the soil's physicochemical composition is frequently altered through the transformation of natural forests to farmland, vast pastureland, and cultivated areas. Understanding the effect of deforestation on soil fertility is the main goal of this review. Farmland, grazing land, land for other uses, and unmanaged forests are the different land use types that were taken into account. This evaluation takes into account features of the soil, such as bulk density, soil texture, and soil physical characteristics, particularly soil moisture content. Contrarily, the chemical characteristics of the soil, such as pH, EC, CEC, soil organic carbon, total N, and accessible P, are taken into account when comparing the various land uses. In forestlands, there were greater levels of clay, Acidity, cation exchange capacity, exchangeable Ca2+, and the amount of organic matter and total nitrogen in the soil. Clay, available phosphorus, and exchangeable K+ were all higher in cultivated land while exchangeable Mg2+ was highest in grazing land. Sand, clay, soil organic matter, cation exchange capacity, exchangeable Ca2+, and Mg2+ all showed a greater mean difference in cultivated land compared to grazing land and forestland