Exchangeable Aluminum Research Articles

Combined BSA-Seq and RNA-Seq Analysis to Identify Candidate Genes Associated with Aluminum Toxicity in Rapeseed (Brassica napus L.).

Exchangeable aluminum (Al) ions released from acidic soils with pH < 5.5 inhibit root elongation of crops, ultimately leading to yield reduced. It is necessary to identify the quantitative trait locus (QTLs) and candidate genes that confer toxicity resistance to understand the mechanism and improve tolerance of rapeseed. In this study, an F2 segregating population was derived from a cross between Al-tolerance inbred line FDH188 (R178) and -sensitive inbred line FDH152 (S169), and the F2:3 were used as materials to map QTLs associated with the relative elongation of taproot (RET) under Al toxicity stress. Based on bulked segregant analysis sequencing (BSA-seq), three QTLs (qAT-A07-1, qAT-A07-2, and qAT-A09-1) were detected as significantly associated with RET, and 656 candidate genes were screened. By combined BSA and RNA-seq analysis, 55 candidate genes showed differentially expressed, including genes encoding ABC transporter G (ABCG), zinc finger protein, NAC, ethylene-responsive transcription factor (ERF), etc. These genes were probably positive factors in coping with Al toxicity stress in rapeseed. This study provides new insight into exploring the QTLs and candidate genes' response to Al toxicity stress by combined BSA-seq and RNA-seq and is helpful to further research on the mechanism of Al resistance in rapeseed.

Improved Straw Decomposition Products Promote Peanut Growth by Changing Soil Chemical Properties and Microbial Diversity

The ameliorative effects of straw decomposition products on soil acidification have been extensively studied. However, the impact of chemically treated straw decomposition products on crop productivity and the underlying microbial mechanisms remain unclear. This study aimed to investigate the effects of two dosages of Ca(OH)2-treated straw decomposition products of peanuts on red soil acidity, fertility, and bacterial and fungal diversity through a pot experiment. The pot experiment included four treatments: chemical nitrogen, phosphorus, and potassium (NPK) fertilization alone (CK), NPK chemical fertilization combined with peanut straw decomposition products (PS), NPK chemical fertilization combined with 4% Ca(OH)2-treated peanut straw decomposition products (PS4Ca), and NPK chemical fertilization combined with 8% Ca(OH)2-treated straw decomposition products (PS8Ca). High-throughput sequencing was performed to investigate the effects of these treatments on soil microbial diversity. The treatments with PS, PS4Ca, and PS8Ca significantly increased soil pH, exchangeable base cations, and nutrient content, whereas they decreased the exchangeable acid, especially exchangeable aluminum. The peanut growth improved substantially with the application of straw decomposition products. Specifically, PS4Ca significantly increased the Shannon and Richness indices of fungi. The principal coordinate analysis showed that the soil microbial communities in the straw decomposition product treatments were significantly different from CK. Linear discriminant analysis effect size identified unique bacteria and fungi between treatments. The Mantel test indicated that exchangeable base cations and pH were significantly positively correlated with bacterial communities, whereas available potassium was positively correlated with fungal communities. The partial least squares path modeling revealed that the bacterial communities positively and directly affected all peanut agronomic traits. In contrast, the fungal communities had a negative and direct effect only on peanut 100-pod weight. Therefore, adding Ca(OH)2-treated straw decomposition products could effectively improve crop productivity by alleviating soil acidification, increasing soil nutrients, and subsequently changing microorganisms.

Exchangeable acidity characteristics of farmland black soil in northeast China

Exchangeable aluminum (Exc-Al), an often overlooked yet indispensable soil parameter, predominantly contributes to soil exchangeable acidity. In this study, we utilized data from 53 sets of surface and subsurface black soil characteristics, including Exc-Al, exchangeable acid (Exc-acid), pH, soil organic matter (SOM), and available and total nutrient levels, to develop a neural network prediction model for estimating Exc-Al and Exc-acid in the black soil area of northeast China. The deterministic neural network model (NNM) was employed to predict Exc-Al and Exc-acid contents in 690 sets of surface and subsurface farmland soil samples with unknown Exc-Al and Exc-acid values. Subsequently, a black soil exchangeable acidity map for northeast China was generated through spatial interpolation. Our results revealed that the average Exc-Al and Exc-acid contents in the 53 surface soils were 0.82 and 0.93 cmol kg−1, respectively, while those in the corresponding subsurface soils were 0.58 and 0.70 cmol kg−1, respectively. Multi-layer perceptron (MLP) neural networks effectively simulated Exc-Al and Exc-acid contents in the surface and subsurface black soils, with calibrated determination coefficients (Radj2) of 0.95–0.96, relative root mean square errors (rRMSE) of 17.3%–24.8%, and statistical significance α at 0.001. The MLP estimations and spatial interpolations revealed that 2.0% and 17.6% of the surface black soil area, and 0% and 3.7% of the subsurface soil area exhibited Exc-Al content exceeding 2.0 and 1.0 cmol kg−1, respectively. Furthermore, 6.7% and 24.9% of the surface black soil area, and 0% and 6.3% of the subsurface soil area showed Exc-acid content exceeding 2.0 and 1.0 cmol kg−1, respectively. These findings break the limitation of relying solely on soil pH as the unique indicator, enrich our knowledge of black soil exchangeable acidity, and enhance our understanding of the black soil acidity status in northeast China.

The improvement of available phosphorous of reclaimed-mining soils with coal fly ash and empty fruit bunches of oil palm treatments

Abstract Reclaimed-mining soil (RMS) were categorized as having an acidic pH, low organic carbon (C), low available phosphorous (P), and high contents of aluminium (Al) and iron (Fe); therefore, soil ameliorants were essentially added to this soil for improving soil fertility. The purpose of the research was to measure the impact of combining empty fruit bunches of oil palm (EFBOP) and coal fly ash (CFA) on the available P of RMS. Three rates of CFA application: 0, 75, and 150 Mg ha−1 and three rates of EFBOP application: 0, 25, and 50 Mg ha−1 were organized using a completely randomized design. A 1000 g of soil was placed to an experimental pot, and then CFA and EFBOP according to the treatment were added to the pot. The mixture of soils, CFA, and EFBOP were homogenized, and then incubated at 70% water holding capacity for 45 days. Available P, total P, Al-P, Fe-P, soil pH, and exchangeable Al were quantifies following the completion of incubation period. The findings of this research indicated that available P rose from 3 mg kg−1 of control (soil without treatment) to 5-41 mg kg−1 of soils with different amounts of CFA and EFBOP addition. The application of CFA and EFBOP also resulted in increases in soil pH from 4.33 in the control to pH 4.48-6.23. Additionally, the levels of Al-P, Fe-P, and exchangeable aluminum decreased with the application of CFA and EFBOP. The findings of this study highlight the potency utilizing industrial and agricultural wastes as soil ameliorants for improving available P to support plant growth on the reclaimed-mining soils.

Amelioration of salt‐affected soil using combined amendments for synergistic effects: Impacts and management implications

AbstractSaline acid sulphate soils are commonly ameliorated using traditional amendments like lime and cow manure. Biochar, derived from crop residues, is another potential remedy for this type of soil. Their combined use may create synergistic effects, necessitating further investigation. This study aims to assess the combined impacts of biochar with traditional amendments on soil quality, properties and rice yield. A field experiment was established with six treatments: no‐amendment (control), lime, cow manure, biochar, combined lime and biochar, and combined cow manure and biochar with rice (Oryza sativa) planted in four replicates. The study revealed that the effects of these amendments on soil properties were driven by their inherent characteristics and secondary processes, such as neutralization. Combining biochar with lime significantly increased soil pH (6.2), and exchangeable calcium (648.6 cmol(+) kg−1), while reducing exchangeable aluminium (11.83 cmol(+) kg−1) and iron (37.5 cmol(+) kg−1), compared to the control. Meanwhile, combining biochar with cow manure notably enhanced Mehlich‐1 phosphorous (3.4 mg kg−1), organic carbon (4.99%), ammonium (27.0 mg kg−1) and cation exchange capacity (17.2 cmol(+) kg−1). Biochar combined with cow manure exhibited greater synergetic effects on soil quality than when combined with lime. Consequently, these combinations improved the soil quality index, which exhibited a strong correlation with rice yield and biomass when its value was below 0.4. This finding indicates that these combinations exhibit insignificant synergistic effects on rice yield and growth. Further research is needed to elucidate these findings and explore the optimal application rates concerning soil properties for improved management practices.

Response of N, P, and metal ions in deep soil layers to long-term cultivation of rubber and rubber-based agroforestry systems

The growing demand for natural rubber products has driven the expansion of rubber plantations in recent decades. While much attention has been given to studying the long-term effects of rubber and rubber-based agroforestry systems on surface soil properties, there has been a tendency to overlook changes in soil properties in deeper layers. Our study addresses this gap by examining alterations in nitrogen (N), phosphorus (P), and metal ion levels in deep soil layers resulting from the prolonged cultivation of rubber and rubber-based agroforestry systems. We found notable shifts in soil NH4+ and NO3− concentrations within the 0–30 cm soil layer across different-aged rubber and rubber-based agroforestry systems. Particularly in mature systems, NO3− and available P levels were close to zero below 30 cm soil depth. Introducing Flemingia macrophylla into young rubber plantations increased soil NH4+ and NO3− in the 0–90 cm soil layer and available P in the 0–10 cm soil layer. Over the long term, cultivation of rubber plantations increased the depletion of total P in the 0–50 cm soil layer, available iron (Fe) and manganese (Mn) in the 30–90 cm soil layer, available copper (Cu) and zinc (Zn) in the 0–90 cm soil layer, accompanied by a decrease in soil pH and increase in exchangeable aluminum (Al) in the 0–90 cm soil layer. Notably, soil exchangeable Al levels exceeding 2.0 cmol kg−1 appeared to induce aluminum toxicity. Furthermore, soil pH below 5.2 triggered a sharp release of exchangeable Al within the 0–90 cm soil layer of rubber plantations, with soil available P nearing zero when exchangeable Al levels assed 7.3 cmol kg−1. Our findings underscore the profound impact of long-term rubber plantation cultivation on surface and deep soil properties. Addressing soil degradation in these deep soil layers poses significant challenges for future soil restoration efforts.

A coffee biochar-mineral NP interaction: Boon for soil health

Low soil fertility, attributed to a deficiency in multiple nutrients, is causing a decline in the productivity of potatoes (Solanum tuberosum) in the Gawata district of southwestern Ethiopia. To address this issue, a field experiment was conducted during the Belg season (February to May) and Meher season (June to October) of the year 2024. The objective was to assess the response of potatoes to the combined application of nitrogen, phosphorus, and coffee biochar (BC) in relation to specific soil physico chemical properties under rainfed conditions. The treatments comprised various combinations of biochar (2.5, 5, 7.5 t ha-1) and inorganic NP (25, 50, and 75%) of the recommended dose (165 kg N ha-1 + 60 kg P ha-1 = 100% recommended dose of fertilizer, RDF), along with 20 t ha-1 of biochar and 100% inorganic NP, with a no-fertilizer treatment serving as the control. In total, there were 12 treatments and a randomized complete block design with three replications was employed for the experiment. The results indicated that the combined application of 75% inorganic NP and 7.5 t ha-1 of biochar significantly increased pH, organic carbon, total nitrogen, available phosphorus, cation exchange capacity, and exchangeable calcium and magnesium. Additionally, it reduced bulk density, exchangeable acidity, exchangeable aluminum, and exchangeable potassium compared to the values obtained from the initial soil test. Consequently, it was concluded that the integrated use of 7.5 t ha-1 of biochar and 75% of inorganic NP during the Belg season, or 25% of it during the Meher season, represents an optimal nutrient management strategy for potato production in the study area.

Modeling the impacts of extreme climate scenarios on soil acidity (pH and exchangeable aluminum) in Abbay River Basin, Ethiopia

The Abbay River Basin faces the looming threat of extreme climate events, including prolonged droughts and erratic rainfall patterns, which can significantly affect soil health and fertility. This study aimed to explore the influence of extreme climate conditions on soil pH and exchangeable aluminum, aiming to promote sustainable agricultural practices in Ethiopia. The Africa Soil Information Service (ASIS) provided datasets on soil pH and exchangeable aluminum. The European Copernicus Climate Change Data Store was used to download historical and future datasets of extreme climatic indices from 1980 to 2010 and 2015–2050, respectively. The Coupled Model Intercomparison Project Phase 6 model ensemble was used to predict future climate impacts under three shared socioeconomic scenarios: SSP1-2.6, SSP2-4.3, and SSP5-8.5. Data extraction, quality control, and clustering were conducted before analysis, and the model was validated for its accuracy and reliability in predicting soil parameter changes. An artificial neural network model was utilized to predict the effects of extreme climate indices on soil pH and exchangeable aluminum concentrations. The model was designed to accurately and reliably predict changes in soil parameters. This study compared the changes in soil pH and aluminum concentrations using paired t tests. The model's diagnostic results indicated a significant impact of extreme climate scenarios on soil pH and exchangeable aluminum. Extreme climate factors such as heavy precipitation and cooler night time temperatures significantly contribute to soil acidification and an increase in aluminum concentration. Under the SSP1-2.6 and SSP2-4.5 emission scenarios, soil pH levels are expected to increase by 8.38 % and 3.79 %, respectively. These changes in soil pH are expected to have significant impacts on the exchangeable aluminum content in the soil, with increases of 37 % and 5.38 %, respectively, under the same emission scenarios. However, the SSP5.8 scenario predicted a 45 % increase in exchangeable aluminum and a 9.36 % decrease in soil pH. Therefore, this study significantly enhances our understanding of the influence of climate change on soil health. The development of strategies to mitigate climate change impacts on agriculture in the region must consider the effects of extreme climate indices.

Studies on the Effects of Liming Acidic Soil on Improving Soil Physicochemical Properties and Yield of Crops: A Review

Soil acidity is a major constraint to crop production globally by potentially limiting agricultural productivity and causing environmental challenges, especially in temperate and tropical regions of the world where there is high precipitation. The review article summarizes the works of literature and gathers information on the effects of liming on soil's physicochemical properties and the yield of crops. Soil acidity is caused by natural ways, such as the high amount of precipitation that exceeds evapotranspiration that leaches appreciable amounts of exchangeable bases from the soil surface, weathering, and decomposition of organic matter and by human interference (by the use of nitrogen fertilizer mainly ammonia and urea fertilizers). Application of lime improved soil pH and neutralize the effect of toxic elements. Liming directly improves some physicochemical properties of the soil, such as aggregates, density, and porosity as physical properties and reduction of exchangeable acidity, Al saturation, micronutrients (Cu, Fe, Mn, and Zn) in the soil solutions, from exchange complex to the levels required and increasing soil pH, exchangeable cations (Na+, K+, Ca+2, and Mg+2) as chemical properties. Soil aggregation, density, and porosity of soil undergo changes with the application of lime. The long-term lime application resulted in increased soil chemical properties. Lime application contributed to increased crop productivity and crop quality. The effects of liming can be explained by the flocculation and cementing action of Calcium ions in the short term. In the long term, increases in productivity induced by liming, result in increasing soil pH, available phosphorus, cation exchange capacity, basic cations, microbial activity, organic carbon, total nitrogen, and decreasing leaching of nutrients, exchangeable aluminum, and acidity, all favoring the physical and chemical properties of the soil.

Evaluation of aluminum tolerance diversity in Avena sativa L. from the VIR collection

Background. Oat is an important food and feed cereal crop in Russia. The area under oats is 10 million ha worldwide, and 3 million ha in Russia. Acid soils with excessive content of exchangeable aluminum occupy almost every third hectare in the exUSSR territory. Oats are relatively resistant to unfavorable soil factors. Among cereal crops, oat is second only to rye and triticale in terms of resistance to exchangeable Al forms. Despite the crop’s high environmental plasticity, an important condition for obtaining sustainable oat yields is the development of new cultivars with resistance to adverse environmental factors, including metal toxicity and high soil acidity.The objective of this work was to search for oat cultivars resistant to soil stressors (excess of Н+ and Al3+) for use in breeding for edaphic resistance.Materials and methods. The research material included 687 oat accessions from the VIR global plant genetic resources collection. The accessions underwent laboratory evaluation of their aluminum tolerance at the initial growth and development stages using the method of measuring radicle growth after the exposure to aluminum stress. Reproducibility of the used modification of the method was mathematically proved.Results and discussion. Significant variation in the resistance to the studied stressor was observed among the accessions. The regions acting as sources of valuable aluminum resistance genes were identified for the crop. The accessions selected for their high resistance to exchangeable aluminum can be used in breeding programs to develop high-yielding oat cultivars with edaphic resistance.

Intercropping herbage promoted the availability of soil phosphorus and improved the bacterial genus structure and the abundance of key bacterial taxa in the acidic soil of mango (Mangifera indica L.) orchards

AbstractThis study aims to understand the characteristics and distribution patterns of soil phosphorus (P) forms in the tropical high‐P orchards under cover cropping and to explore the biotic and abiotic factors driving the changes in P forms. The study collected three kinds of soil (clean tillage [CK, control], Stylosanthes guianensis cover [SC, legume], and Cynodon dactylon (L.) Pers. cover [CC, grass]) from a mango orchard and determined P forms in the water‐stable aggregates and bulk soil, analyzed the environmental factors and the structure of the bacterial‐fungal community. Compared to CK, SC and CC have a significant positive influence on the forms and distribution of soil P, increase the content of organic P (Org‐P) and certain inorganic P forms (Al‐P and Fe‐P), and enhance the content of P within macroaggregates (&gt;0.25 mm), thereby maintaining total P (TP) and Olsen‐P in the top 30 cm of soil, particularly for the SC treatment. SC and CC also improved acid phosphatase (ACP), and water‐stable aggregates while decreasing bulk density (BD) and exchangeable aluminium (Ale) in the topsoil (0–15 cm). Redundant and Pearson analysis revealed these factors significantly affected soil P availability. Moreover, SC and CC increased the relative abundance of Nitrospira, Candidatus‐Udaeobacter, Pseudolabrys, and ADurb.Bin063–1 in the topsoil (0–15 cm), and decreased the relative abundance of Occallatibacter. Redundant and Pearson analysis indicated that these bacterial communities are likely associated with the availability of P. Overall, cover cropping promoted the transformation and distribution of P forms by altering the physical, chemical, and biological environment of the soil, which was beneficial for the sustainable P management in tropical high‐P soils. This research offers practical insights into the use of cover crops as a tool for enhancing soil health and sustainable P management in tropical high‐P orchards.

Effectiveness of micro-dosing of lime on selected chemical properties of soil in Banja District, North West, Ethiopia

Abstract Soil acidity significantly impacted the agricultural productivity of Ethiopia. Liming has been used as a soil ameliorator, albeit it was not successful due to inadequate availability, high cost, and poor infrastructure for lime transportation to the required agricultural land area. Hence, soil amendment with a minimum amount of lime application is a viable option to improve agricultural productivity sustainably. Therefore, this study aimed to investigate the effectiveness of micro-dosing lime on selected chemical properties of acidic soil in North West, Ethiopia. Three lime application methods and eight treatment approaches were used in the field experiment employing a randomized complete block design with four replications. Independent soil samples were collected before and after liming and analyzed for selected chemical properties. Data were analyzed by analysis of variance using SPSS version 22.0 and SAS 9.3. The application of lime had a significant impact (p &lt; 0.01) on the selected soil chemical properties. Micro-dose application of lime efficiently affected the selected soil chemical properties. The results showed that water pH, available phosphorus, cation exchange capacity, and organic carbon exhibited a considerable increase per kg of applied lime: 2.5 × 10−3, 101.3 × 10−3 (mg kg−1), 160 × 10−3 (Cmol(+) kg−1), and 3 × 10−3%, respectively. Conversely, exchangeable aluminum and exchangeable acidity decreased per kg of applied lime by 7.8 × 10−3 (Cmol(+) kg−1) and 12.2 (Cmol(+) kg−1) × 10−3, respectively. Therefore, the micro-dosing lime application proved to be more effective in influencing these soil properties than other application methods, emphasizing its potential as a valuable soil amendment strategy for small-scale farming.

Improved soil moisture, nutrients, and economic benefits using plastic mulchs in balsa-based agroforestry systems.

The manufacture of wind turbine blades generally uses balsa wood as the base materials, and it is crucial to explore new regions for cultivating balsa trees to achieve carbon neutrality in the future. Xishuangbanna may be China's only area with a tropical climate suitable for the large-scale planting of balsa trees. The present study investigated the key soil elements influencing the growth of balsa plantations and the effects of different cultivation practices on soil environments and economic benefits in Xishuangbanna, China. We found that the height of balsa stems after growing 4years reached 5.8m; the increment of diameter at breast height (DBH) reached 27.7cm and volume of balsa stems reached 196.0 m3ha-1 in Xishuangbanna of China. It is of the utmost importance to improve the contents of soil exchangeable magnesium (Mg) and available phosphorus (P) for the growth of balsa trees, and exchangeable aluminium (Al) inhibited the growth of balsa trees. The practice of plastic film mulching not only improved soil moisture in the 40‒100-cm soil layer in the dry season and in the 0-60-cm soil layer in the rainy season but also enhanced soil nitrate nitrogen when compared with no plastic-mulching practice in balsa plantations. The comprehensive economic benefits of balsa/coriander/ginger/taro plantations were significantly improved by implementing plastic film mulching, as compared to balsa plantations. We conclude that balsa tree can be cultivated in Xishuangbanna, China, and its successful cultivation provides opportunities for China's wind power development.

Application of Dolomite as Soil Conditioner to pH and Exchangeable Al in Inceptisol

Soil fertility is the state of the soil where water, water and nutrients are in a state that is quite balanced and can be obtained according to the needs of plants, including the physical, chemical and biological needs of the soil. Lack of soil fertility will affect plant growth and productivity so that it is less than optimal. Therefore, it is very necessary to increase soil fertility through soil improvement, one of which is dolomite. Inceptisols are soil orders that have not developed further with the characteristics of a thick solum between 1.5-10 meters above the parent material, reacts acidly with a pH of 4.5-6.5, if it undergoes further development the pH increases to less than 5.0, and base saturation is from low to low. currently. The texture of this whole solum is generally clayey, while the structure is crumbly and the consistency is loose. In general, the fertility and chemical properties of Inceptisols are relatively low, but efforts can still be made to improve with appropriate handling and technology, pH in Inceptisol soils is one of the obstacles in efforts to increase soil productivity. The application of dolomite on acidic agricultural soils is to reduce or eliminate the adverse effects of acid soils, which generally contain high enough quantities of exchangeable aluminum ions so that they can poison plants. This test was carried out at the Experimental Field of the Chemical Laboratory of Soil Fertility and Plant Nutrition, Department of Soil Science and Land Resources, Faculty of Agriculture, Universitas Padjadjaran, Jatinangor, Sumedang Regency, West Java, which is located at an altitude of 794 m above sea level. The experiment used a randomized block design (RAK). In accordance with the objectives of the experiment, five dolomite test treatments were set with five replications. Dolomite affects the process of increasing pH and decreasing exchangeable Al. Giving the test dose of dolomite equivalent to 1.5 doses of dolomite was able to increase pH and decrease Al-exchable.

Soil Properties and Forest Decline in the North-Western Part of Romania

The paper presents the study of the soil quality and health expressed by the chemical and biological properties in a research field placed at Varciorog, Bihor County, Romania. The soil samples were collected from 3 soil variants in March 2023. In each soil variant, some soil chemical parameters and the abundance of bacteria were determined. The frequency and intensity of colonization, along with arbuscules and vesicles, were scored to determine the mycorrhizal potential of each soil. The community-level physiological profile was used to determine the functional microbiome and its ability to decompose a specific set of substrates. In the control variant (CTRL), which is a functional forest cultivated with beech in a proportion of 90%, the soil properties were compared with those determined from Site 1 (a declined mixed forest) and from Site 2 (chestnut forest in a stage of complete drying). The data were statistically processed with a one-way ANOVA test, followed by the Duncan post-hoc test, which revealed significant variation in the potential of microbial functional communities across the analyzed sites. Also, the soil parameters that significantly varied in the 3 soil variants were bacterial number, pH, humus, exchangeable aluminum, coarse sand, dust, and fine sand. The Pearson correlation was computed to study the links between bacterial numbers and chemical parameters. The results showed strong correlations between most of the studied soil properties. The Ecoplates approach to soil functional microbiome highlighted various differences between the microbial communities of the three tested sites. Mycorrhizal colonization shows different potentials for symbiosis formation. The peak of mycorrhizal colonization was in declined forest, with 43.36% colonization frequency and 24.56% intensity. Arbuscules reached 11.36% in declined forest, while in control and decayed sites, the indicator was under 4%. Vesicles are more associated with control and decayed forests, with values of presence over 1.30%. As an indicator of microbial general activity, the sum of recorded activities was higher in declined and decayed forests. At these sites, the activity of the functional microbiome was amplified. The decline process activates a higher diversity of functional groups and is associated with a larger area of substrate decomposition capacity, which indicates a more extensive range of microbial functions related to breaking down organic matter.

CHEMICAL CHARACTERIZATION OF SOME AGRICULTURAL LAND OF THE ARGES COUNTY SUB-CARPATHIAN AREA

The High Plain of Pitesti in the south of Arges county is an excellent location for food production. However, Arges county is experiencing a significant decrease in productivity due to the acidity of its soil. This acidity is related to the behavior of certain soil properties essential for plant growth. The present work aims to study the pH behavior according to certain chemical parameters such as: exchangeable aluminum. To achieve this goal, forty-four soil samples were taken in the Costesti locality and sent to the soil laboratory where physical-chemical analyzes were performed. High concentrations of Al3+ in the nutrient solution cause harmful effects on the roots, which undergo morphological changes, turn black, reduce their growth in length and thickness, and fundamental changes in the capacity to absorb and retain cations occur. Thus, Al3+ ions cause a desorption of Ca2+, K + and Mg2+ ions and other species of cations from the pectocellubasic layer of root hairs, worsening nutrition, the absorption of these cations decreasing and increasing that of Al3+. It also reduces phosphorus nutrition, which precipitates as aluminum phosphates on the root surface. The risks of aluminum toxicity should not be overlooked. The rate of ammonia fertilizer use in the study area should be reduced, especially in soils with a pH below 5.4. It is recommended that strong bases input be used in these slightly acidic or acidic soils.

Variation in soil characteristics of ex-coal mining areas in Sawahlunto, West Sumatra

Soil characteristics in ex-coal mining areas can be influenced by reclamation methods and the type and age of revegetation plants used. This reclamation can also significantly impact the soil chemistry of ex-mining areas. This research was conducted in ex-coal mining areas located in Parambahan, Batu Tanjung Village, Talawi District, Sawahlunto City, West Sumatra Province. The objective of this study is to analyze variations in the reclamation process and their effects on the chemical properties of soil in these areas. Observations were made in several plots, including land that had not been mined (natural forest), land revegetated with Acacia in the planting years of 1992, 2007, 2010 (without the use of topsoil), 2019, and 2021, and land revegetated with Sengon in 2022. In each plot, soil samples were collected at three depths: 0–5 cm, 5–10 cm, and 10–20 cm, to analyze soil chemical properties. These properties included pH, total nitrogen (N), available phosphorus (P), organic carbon (C), exchangeable base cations (K, Ca, Mg, and Na), cation exchange capacity, and exchangeable aluminum (Al). The results showed that variations in the years of revegetation and reclamation practices, such as the use of topsoil and plant types, significantly influenced soil chemical characteristics. The longer the period of revegetation, the better the improvement in the soil’s chemical properties, as indicated by changes in pH, total N, organic C, exchangeable K, Na, Ca, and Mg, cation exchange capacity, and a reduction in exchangeable Al. However, the availability of P, as indicated by available P, decreased after more than 30 years of revegetation.

Fertilidade e estoque de carbono em ambientes de pastagem e floresta no sul da Amazônia

ABSTRACT Inadequate management of pasture soils in the Amazon has resulted in a predominance of degraded pastures. Considering the natural characteristics of this region can favor more appropriate strategies for sustainability, the objective of this study was to evaluate the differences in the chemical and physical attributes of pasture and forest soils in the Southern Amazon and to identify the most sensitive attributes of their fertility. Additionally, this study suggests appropriate management practices for sustainable pastures. Soil samples from the 0 to 0.20 m layer were analyzed to determine pH, exchangeable bases (calcium, magnesium, and potassium), exchangeable aluminum, potential acidity, phosphorus, organic carbon, bulk density, and texture. Pasture soils had a higher pH, calcium content, and bulk density than forest soils. However, the pasture soils had lower phosphorus and organic matter content. The soil organic carbon stocks were also lower in pasture soils, with levels 0.8 to 12 Mg ha-1 lower than in forest soils. The fertility attributes most sensitive to soil management in these pastures were phosphorus, pH, organic carbon, and bulk density. The lack of nutrients and soil and water conservation practices have contributed to the degradation of these pastures. Therefore, the recommended management for these pastures should aim to improve the organic matter content, reduce compaction, and replenish and cycle nutrients.

Assessment of Physicochemical Properties and Heavy Metal Content of Floriculture Soil in Amhara Region of Northwest Ethiopia.

Floriculture is a new and rapidly expanding sector in Ethiopia that aids economic growth but has also come under blame for pollution of the surrounding soil. The purpose of this study was to assess the soil physicochemical properties and heavy metal contents in floriculture in the Amhara Region of Northwest Ethiopia. Soil samples were collected from seven different greenhouses (2ABC, 4DEF, 5ABC, 7DEF, 8ABC, 9DEF, and 11DEF), and a control soil sample was taken on the 15-cm depth from a nearby agricultural area. They were analyzed for soil physicochemical parameters and heavy metal compositions. Soil texture showed a significant difference between the soils sampled from the greenhouses and the control group. The highest average clay, silt, and sand contents were recorded in the control group, 4DEF, and 9DEF, respectively. The lower clay content was at 9 DEF, silt at 11 DEF, and sand in the control group. Clay was positively correlated to soil pH (r = 0.66) and TN (r = 0.38) but showed significant negative correlation with the sand fraction (r = -0.96). The average bulk density (BD) values of the soils from the greenhouses were within acceptable ranges; however, the mean BD value of 7DEF was relatively highest (1.34 g/cm3). There were significant (P < 0.05) changes in soil pH and electrical conductivity, with pH values ranging from 5.8 to 7.17 and EC from 0.08 to 1.72 mScm-1. Soil organic carbon, available phosphorus, total nitrogen, and carbon-to-nitrogen ratio of the soil samples from the greenhouses and the control group were significantly different. There were also significant differences in soil exchangeable aluminum and acidity between greenhouse soil samples and the control group. Soil contents of some of the heavy metals (Pb, Cd, Mn, and Cu) in the floriculture soil were above the permissible limits, while Cr, Zn, and Ni contents were below. The soil in floriculture showed low quality compared to the control group and international standards, indicating the need for improved soil quality management. This study recommends reducing agrochemical use, increasing bio-fertilizers, using botanicals, and transitioning to organic farming. Further studies are needed to assess soil microbial diversity and abundance for soil fixation.

Soil carbon and nitrogen contents in forest soils are related to soil texture in interaction with pH and metal cations

The aim of this study was to better understand how soil carbon (C) and nitrogen (N) contents and the C:N ratio are related to soil texture, pH, and exchangeable aluminum and calcium in forest soils.For this purpose, we studied 1992 temperate and boreal forest soils located all over Sweden. We measured organic C and N as well exchangeable aluminum, calcium, and pH in the organic layer and three depth increments in the mineral soil (down to 65 cm), and analyzed the relationship between element contents, soil texture, and soil pH as well as their interactions.Soil C concentration and the C:N ratio were negatively related to soil pH. The C concentration was on average 2.6 times higher in very acidic soils (pH ≤ 4.0) than in soils with pH > 5.0, in the uppermost 10 cm of the mineral soil. In contrast, N varied much less with pH, particularly in the organic layer, but was related to soil texture. The N concentration was 2.3 times higher in clayey and fine silty soils than in sandy soils, while the C concentration was only 1.85 times higher in clayey and fine silty soils than in sandy soils (in the uppermost 10 cm). Differences in C and N concentrations between clayey and fine silty soils compared to sandy soils were largest in the class of soils with pH > 5.0 and smallest in the class of soils with pH ≤ 4.0. Furthermore, C and N concentrations were both positively correlated with the concentration of exchangeable aluminum in the mineral soil, and these correlations were stronger in coarse-textured than in fine-textured soils. In addition, the C concentration was positively correlated with the concentration of exchangeable calcium in the organic layer.In conclusion, our results show that C concentration varied much more strongly with pH than N concentration, likely due to effects of pH on microbial respiration. The N concentration was more strongly related to soil texture than the C concentration, which is very likely due to the high charge density of organic N, which gives organic N a high affinity to adsorb to mineral surfaces. Furthermore, exchangeable aluminum seems to play an important role in the sorptive stabilization of organic matter in the mineral soil.