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Biochars were produced at 350 °C and applied at varying rates (0, 52, 104, and 156 Mg ha−1 and incubation times up to 120 days. Both biochars and limestone significantly improved soil properties like pH, electrical conductivity, cation exchange capacity (CEC), and nutrient availability. Limestone proved most effective, raising pH by 1.3 units on average and increasing EC and CEC, followed by Cadia purpurea- and Tarchonanthus camphoratus-based biochars. Biochars also increased pH, with Cadia purpurea showing the greatest effect (up to a 1.49 unit increase at the highest rate of application). These findings suggest biochar from these expansive plants holds promise for improving acidic soils. However, the optimal application rate, incubation times, and type of amendment (biochar or limestone) likely depend on specific soil characteristics and goals. Further research is needed to explore long-term effects, combined amendment approaches, and cost-effectiveness for long-term soil health, agricultural productivity, and environmental well-being. [ABSTRACT FROM AUTHOR]

Aims: Biological nitrogen (N) fixation (BNF) driven by diazotrophs plays an essential role in reducing N fertilizer input in acidic soils. Amendments improve the acidic soil environment and increase crop N utilization; however, whether their effects on soil BNF and diazotrophs contribute to crop N utilization remains unclear. Methods: A 5-year field trial was implemented to assess the effects of the sole or joint application of organic and inorganic amendments (straw, manure and alkaline slag) on soil BNF rates, canola N utilization, and diazotrophic communities of acidic bulk and rhizosphere soils. Results: Amendments, especially joint application of organic and inorganic amendments, significantly increased canola biomass, N utilization, soil BNF rates, and diazotrophic abundance. There were positive correlations among BNF rates, N uptake and physiological N use efficiency of canola. Both amendments and canola planting significantly affected the structure of diazotrophic communities, with the stronger effects in the joint application of organic and inorganic amendments. Influences of soil C/N, SOC and diazotrophic α-diversity on BNF rates in rhizosphere soils were greater than in bulk soils. The dominant genus affecting BNF rates differed between bulk and rhizosphere soils. Rhizosphere BNF rates were positively correlated with the number of nodes, total edges, and positive correlations of edges of rhizosphere diazotrophic network, but not in bulk soils. Conclusion: The improved soil BNF by organic and inorganic amendments in acidic soils have positive effects on crop N utilization, and the mechanisms underlying the contribution of diazotrophs to BNF rates differ in bulk and rhizosphere soils. [ABSTRACT FROM AUTHOR]

The widespread occurrence of acidic soils presents a major challenge for agriculture, as it hampers productivity via a combination of mineral toxicity, nutrient deficiency, and poor water uptake. Conventional remediation methods, such as amending the soil with lime, magnesium, or calcium, are expensive and not environmentally friendly. The most effective method to mitigate soil acidity is the cultivation of acid-tolerant cultivars. The ability of plants to tolerate acidic soils varies significantly, and a key factor influencing this tolerance is aluminum (Al) toxicity. Therefore, understanding the physiological, molecular, and genetic underpinnings of Al tolerance is essential for the successful breeding of acid-tolerant crops. Different tolerance mechanisms are regulated by various genes and quantitative trait loci in various plant species, and molecular markers have been developed to facilitate gene cloning and to support marker-assisted selection for breeding Al-tolerant cultivars. This study provides a comprehensive review of the current developments in understanding the physiological and molecular mechanisms underlying Al resistance. Through the application of genome-wide association methods, it is expected that new Al-resistant genes can be identified and utilized to cultivate Al-resistant varieties through intercrossing, backcrossing, and molecular marker-assisted selection, promoting the sustainable use of acidic soils. [ABSTRACT FROM AUTHOR]

The study is the first to examine the combined use of blast-furnace sludge as a source of microelements and converter slag as a soil-deoxidizing agent in oat (Avena sativa L.) cultivation in sod-podzolic soils. It has been established that blast-furnace sludge is a highly dispersed waste, which contains about 50% iron, 7% zinc, and a small amount of calcium, silicon, magnesium, aluminum, and sulfur. Hazardous components such as lead, arsenic, etc., are not detected. Converter slag comprises porous granules up to 3 mm in size, consisting mainly of calcium compounds (CaO, Ca(CO)3, CaSiO3, CaFe2O4) and a small amount of Mn, Al, and Mg trace elements. In a laboratory experiment, blast-furnace sludge increased the germination of oats by 5–10%, regardless of the addition of a deoxidizer (slag), but at the same time suppressed the growth of stem length by a maximum of 18% at 1 g∙kg−1. The addition of slag raised substrate pH and increased the index by 8% at a sludge concentration of 0.1 g∙kg−1. Root length in deoxidizer-free variants increased by 50–60% and with the addition of slag by 27–47%. Root dry mass also increased under the addition of sludge by 85–98%; however, the addition of slag reduced the indicator to the control level. In a field experiment with the combined application of waste, an increase in yield by more than 30% was shown. When soil was treated with slag and sludge, the height of plants increased by an average of 18%. It should be noted that the introduction of waste did not affect the quality of the grain. The use of slag increased the lead content in the soil, which is probably due to the sorption properties of calcium compounds in the slag, since lead was not found in the analyzed waste. Presumably, lead is sorbed by slag from the lower soil horizons, concentrating and immobilizing it in the upper layer. This version is supported by the absence of lead accumulation in straw and oat grain. The zinc-containing sludge increased the content of this element by 33% in the soil, as well as by 6% in straw and by 14% in grain. Thus, we found that the studied metallurgical wastes can be used as nutrients for agriculture, both individually and jointly. Overall, the proposed approach will contribute both to reducing the amount of accumulated waste and to improving the efficiency and sustainability of agricultural production and CO2 sequestration. However, the features of the accumulation of heavy metals in soil and plants under the influence of the analyzed types of waste require more in-depth study, including within the framework of long-term field experiments. [ABSTRACT FROM AUTHOR]

Rice provides poor yields in acidic soils due to several nutrient deficiencies and metal toxicities. The low availability of phosphorus (P) in acidic soils offers a natural condition for screening genotypes for grain yield and phosphorus utilization efficiency (PUE). The objective of this study was to phenotype a subset of indica rice accessions from 3000 Rice Genome Project (3K-RGP) under acidic soils and find associated genes and alleles. A panel of 234 genotypes, along with checks, were grown under low-input acidic soils for two consecutive seasons, followed by a low-P-based hydroponic screening experiment. The heritability of the agro-morphological traits was high across seasons, and Ward's clustering method identified 46 genotypes that can be used as low-P-tolerant donors in acidic soil conditions. Genotypes ARC10145, RPA5929, and K1559-4, with a higher grain yield than checks, were identified. Over 29 million SNPs were retrieved from the Rice SNP-Seek database, and after quality control, they were utilized for a genome-wide association study (GWAS) with seventeen traits. Ten quantitative trait nucleotides (QTNs) for three yield traits and five QTNs for PUE were identified. A set of 34 candidate genes for yield-related traits was also identified. An association study using this indica panel for an already reported 1.84 Mbp region on chromosome 2 identified genes Os02g09840 and Os02g08420 for yield and PUE, respectively. A haplotype analysis for the candidate genes identified favorable allelic combinations. Donors carrying the superior haplotypic combinations for the identified genes could be exploited in future breeding programs. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) contamination in agricultural soils is a common issue, posing health risks as it enters the human body through the food chain. Commonly used phosphate fertilizers (PFs) not only provide essential phosphorus (P) nutrients to crops but also serve as P-containing materials for immobilizing heavy metals (HMs) like Cd in soils. Therefore, understanding the passivation effects of PFs on soil Cd and their potential influencing factors is crucial for mitigating soil Cd pollution. In this study, the impact of multi-crop applications (75 mg P kg−1, 150 mg P kg−1) of four kinds of PFs on reducing soil Cd toxicity and decreasing Cd accumulation in spinach was investigated. The results indicated that under the low application rate (75.0 mg P kg−1), all PFs could passivate Cd, and CMP demonstrated the most effective passivation of Cd. However, under the high application rate (150 mg P kg−1), the immobilization effect diminished or even activated Cd. Among the different types of PFs, CMP application alleviated soil acidification and significantly reduced soil-available Cd, showing the best performance in promoting spinach growth and Cd inhibition. These results suggest that PF application in Cd-contaminated soils affects spinach growth and Cd accumulation, with soil pH, available phosphorus (AP), and Cd dynamics being crucial; moreover, low-P, micronutrient-rich, alkaline PFs like CMP optimize spinach yields and minimize Cd uptake, and excessive application of soluble PFs decreases pH, increases Cd mobility, and poses health risks, suggesting a need for balanced fertilizer use. [ABSTRACT FROM AUTHOR]

Biochars were produced at 350 °C and applied at varying rates (0, 52, 104, and 156 Mg ha−1 and incubation times up to 120 days. Both biochars and limestone significantly improved soil properties like pH, electrical conductivity, cation exchange capacity (CEC), and nutrient availability. Limestone proved most effective, raising pH by 1.3 units on average and increasing EC and CEC, followed by Cadia purpurea- and Tarchonanthus camphoratus-based biochars. Biochars also increased pH, with Cadia purpurea showing the greatest effect (up to a 1.49 unit increase at the highest rate of application). These findings suggest biochar from these expansive plants holds promise for improving acidic soils. However, the optimal application rate, incubation times, and type of amendment (biochar or limestone) likely depend on specific soil characteristics and goals. Further research is needed to explore long-term effects, combined amendment approaches, and cost-effectiveness for long-term soil health, agricultural productivity, and environmental well-being.

Potentiometric titration in a fast and simultaneously high-resolution modality was proposed for the identification and quantification of protolytic groups of variable strength at the surface of primary soil particles. The method is implemented by titrimetric data processing as multicomponent spectra (pKa spectrotitrimetry). Due to the high resolution, the error of acidity-constant assessment (3–5%) is lower, compared to existing approaches; due to the fast titration, the effect of soil hydrolysis is minimized. The soil profiles for acidic Retisols (podzolic soils)—under a spruce crown and in the intercrown space—were studied. These soils, which have similar bulk properties and genesis but developed under different plant covers, were distinguished by pKa spectral features at 4–5; 5.5–6.5; 6.5–8.5; 7.5–8.5; and 9–10, as well as total group concentrations. Differences in acidic and basic-group distribution (carboxyl groups, amorphous aluminosilicates, carbonate species, amino groups, soluble (poly)phenolic compounds, phospholipids) and Al and Fe complex compounds within the same soil profiles and between two Retisols were found and quantified. The acidity constants and group concentrations found by pKa spectrotitrimetry were compared with conventional soil-composition indicators (total organic carbon, oxalate-soluble Fe and Al, and phosphorus), using principal component analysis. The main correlations are between the concentrations of oxalate-soluble Al and groups with pKa values of 5.0–6.5 and 8.5; oxalate-soluble Fe and pKa values of 9.0–10.0; and P2O5 and pKa values of 4.0–6.0 and 6.5–8.5. The method provides a set of major acidity values without a priori information on a soil sample and can be used for screening and identifying similar soils. [ABSTRACT FROM AUTHOR]

Phosphorus availability is a serious problem for plants growing and grown in acidic soils of bogs, poor in macronutrients. The application of phosphorus fertilizers to such soils is unprofitable because of the physical and chemical properties of these soils, where phosphate is firmly bound to organic and inorganic compounds and becomes inaccessible to plants. Plants of the Vaccinium genus both from natural stands and commercial plantations may suffer from phosphorus deficiency, so they need to have a number of adaptations that allow them to efficiently extract phosphorus. This review addresses the following issues in relation to plants of the Vaccinium genus: sources of phosphorus for plants; the release of phosphate ions from soil components; the transport of phosphate ions into plants; and the importance of mycorrhiza in supplying phosphorus to plants. Thus, we sought to draw researchers' attention to sources and routes of phosphorus supply of plants of the Vaccinium genus and its unexplored aspects. [ABSTRACT FROM AUTHOR]

Due to its adsorption with aluminum and iron hydroxides, phosphorus viability is low in acidic soils; thus, the aim of this study was to isolate and identify bacteria from the rhizosphere of four legumes growing in acidic soils of the Cumbaza Sub-basin, San Martín, Peru, as well as to characterize their ability to solubilize aluminum phosphate and iron phosphate. The isolation process was conducted on TSA medium and the isolates were classified based on their origin and morphocolonial characteristics, with the bacillary shape being the most frequent, followed by cocci. To assess the solubilization of aluminum and iron phosphates, the liquid medium GELP was employed. Sixteen strains were selected, among which three stood out for their effectiveness in solubilizing AlPO4 (Sfcv-098-02, 22.65 mg L−1; Sfc-093-04, 26.50 mg L−1; and Sfcv-041-01-2, 55.98 mg L−1) and one for its ability to solubilize FePO4 (Sfcr-043-02, 32.61 mg L−1). These four strains were molecularly characterized, being identified as Enterobacter sp., Pseudomonas sp., and Staphylococcus sp. Additionally, a decrease in pH was observed in the reactions, with values ranging from 5.23 to 3.29, which enhanced the phosphate of solubilization. This suggests that the selected bacteria could be used to improve phosphorus availability in agricultural soils. [ABSTRACT FROM AUTHOR]

Pre-harvest burning of sugarcane is a major management system globally and could have a significant effect on soil organic carbon (SOC) fractions, aggregates stability and nutrient cycling, while green cane harvest system can be more beneficial to soil quality and environmental sustainability. The current study examined the effects of sugarcane harvest systems on SOC fractions and aggregate stability of sandy loam Umbric Rhodic Ferralsols, with relatively high SOC. Soil aggregate stability was determined using the wet-sieving method. SOC fractions were determined using the physical and chemical separation method, thereafter the SOC content in different fractions was determined by the wet oxidation method. Pre-harvest burning reduced soil aggregate stability by >100 and 64.3% when compared to green cane in the top 0–5 and 5–10 cm depths, respectively. The carbon in the macro-aggregates fraction constituted more than 60% of total SOC, making it the primary C storage fraction for both green cane and pre-harvest burning. Pre-harvest burning had 20.4 and 45.2% lower SOC content in macro- and micro-aggregate fractions, respectively, when compared to green cane. Also, coarse particulate organic matter carbon and fine particulate organic matter carbon were lower in pre-harvest burning management after the dispersion of macro-aggregates when compared to green cane. Pre-harvest burning increased mineral-associated C in µSilt + µClay from bulk soil fractionation by 23.7% when compared to green cane. All the C fractions decreased with an increase in soil depth in both green cane and pre-harvest burning, except for the mineral-associated C. These findings demonstrate that green cane production increases aggregate stability and SOC storage in different soil fractions, with a potential reduction in greenhouse gas emission and sustainable sugarcane production when compared with the pre-harvest burning on sandy loam Umbric Rhodic Ferralsols. [ABSTRACT FROM AUTHOR]

Interactions between Galba truncatula and two species of land snails (Cochlicopa lubrica, Succinea putris) that colonise lymnaeid habitats in June-July were studied by introducing G. truncatula into new sites (Experiment A) or removing it from its natural habitats (Experiment B). Snail counts were performed in late May or early June for the eight years following introduction or removal of G. truncatula. The results were compared to those observed at control sites where G. truncatula was absent. In sites where G. truncatula was introduced (Experiment A), the mean density of the lymnaeid peaked in the second year and gradually decreased in subsequent years. Conversely, the mean density of the land snails decreased sharply in the second year before increasing rapidly for S. putris and gradually for C. lubrica in subsequent years. Removal of G. truncatula from its natural habitats (Experiment B) had no significant effect on the mean density of C. lubrica. In contrast, that of S. putris peaked in the second year and decreased rapidly to lower values in subsequent years. Density interactions between G. truncatula and the two land snail species indicate that there is probably competition between these species for space in lymnaeid habitats in May and June. [ABSTRACT FROM AUTHOR]

We grew three yellow Camellia species (the calcifuge C. nitidissima and C. tunghinensis, and the calcicole C. pubipetala) in acidic and calcareous soils for 7 months and assessed their photosynthetic physiological characteristics, growth performance, and element concentrations in this developmental context. The calcifuge C. nitidissima and C. tunghinensis species exhibited poor growth with leaf chlorosis, growth stagnation, and root disintegration in calcareous soils, and with their P n, G s, T r, F v/F m, ΦPSII, ETR, qP, leaf Chla, Chlb, and Chl(a + b) concentrations, and root, stem, leaf, and total biomass being significantly lower when grown in calcareous soils relative to in acidic soils. In contrast, the calcicole C. pubipetala grew well in both acidic and calcareous soils, with few differences in the above parameters between these two soil substrates. The absorption and/or transportation of nutrient elements such as N, K, Ca, Mg, and Fe by the two calcifuge Camellia species plants grown in calcareous soils were restrained. Soil type plays a major role in the failure of the two calcifuge Camellia species to establish themselves in calcareous soils, whereas other factors such as competition and human activity are likely more important limiting factors in the reverse case. This study furthers our understanding of the factors influencing the distribution of these rare and endangered yellow Camellia species, allowing for improved management of these species in conservation projects and horticultural production.

Peatland degradation might affect peatland functions. Sustainable agriculture practice, i.e., nutrient management, is one of the efforts that could be made to delay the degradation. Therefore, this research aimed to identify the best nutrient management practice for shallot production in degraded peatlands. A split-plot experimental design was performed in a greenhouse environment, with cultivars (Sembrani and Trisula) as the main plot and eleven combinations of NPK fertilizer as the subplot. All treatments received 4.4 t ha-1 dolomite to increase the soil pH. Results showed that Sembrani produced a higher bulb yield than Trisula. Trisula was sensitive to acidic soils and failed to yield a high bulb. The NPK recommended dose for Sembrani was 150 kg N ha-1, 100 kg P2O5 ha-1, and 100 kg K2O ha-1, producing 57.50 g plant-1 equal to 14.4 t ha-1 or 53% higher than the control (without NPK). Meanwhile, growing Trisula was not recommended for peatlands.

The study is the first to examine the combined use of blast-furnace sludge as a source of microelements and converter slag as a soil-deoxidizing agent in oat (Avena sativa L.) cultivation in sod-podzolic soils. It has been established that blast-furnace sludge is a highly dispersed waste, which contains about 50% iron, 7% zinc, and a small amount of calcium, silicon, magnesium, aluminum, and sulfur. Hazardous components such as lead, arsenic, etc., are not detected. Converter slag comprises porous granules up to 3 mm in size, consisting mainly of calcium compounds (CaO, Ca(CO)3, CaSiO3, CaFe2O4) and a small amount of Mn, Al, and Mg trace elements. In a laboratory experiment, blast-furnace sludge increased the germination of oats by 5–10%, regardless of the addition of a deoxidizer (slag), but at the same time suppressed the growth of stem length by a maximum of 18% at 1 g∙kg−1. The addition of slag raised substrate pH and increased the index by 8% at a sludge concentration of 0.1 g∙kg−1. Root length in deoxidizer-free variants increased by 50–60% and with the addition of slag by 27–47%. Root dry mass also increased under the addition of sludge by 85–98%; however, the addition of slag reduced the indicator to the control level. In a field experiment with the combined application of waste, an increase in yield by more than 30% was shown. When soil was treated with slag and sludge, the height of plants increased by an average of 18%. It should be noted that the introduction of waste did not affect the quality of the grain. The use of slag increased the lead content in the soil, which is probably due to the sorption properties of calcium compounds in the slag, since lead was not found in the analyzed waste. Presumably, lead is sorbed by slag from the lower soil horizons, concentrating and immobilizing it in the upper layer. This version is supported by the absence of lead accumulation in straw and oat grain. The zinc-containing sludge increased the content of this element by 33% in the soil, as well as by 6% in straw and by 14% in grain. Thus, we found that the studied metallurgical wastes can be used as nutrients for agriculture, both individually and jointly. Overall, the proposed approach will contribute both to reducing the amount of accumulated waste and to improving the efficiency and sustainability of agricultural production and CO2 sequestration. However, the features of the accumulation of heavy metals in soil and plants under the influence of the analyzed types of waste require more in-depth study, including within the framework of long-term field experiments.

Peatland degradation might affect peatland functions. Sustainable agriculture practice, i.e., nutrient management, is one of the efforts that could be made to delay the degradation. Therefore, this research aimed to identify the best nutrient management practice for shallot production in degraded peatlands. A split-plot experimental design was performed in a greenhouse environment, with cultivars (Sembrani and Trisula) as the main plot and eleven combinations of NPK fertilizer as the subplot. All treatments received 4.4 t ha-1 dolomite to increase the soil pH. Results showed that Sembrani produced a higher bulb yield than Trisula. Trisula was sensitive to acidic soils and failed to yield a high bulb. The NPK recommended dose for Sembrani was 150 kg N ha-1, 100 kg P2O5 ha-1, and 100 kg K2O ha-1, producing 57.50 g plant-1 equal to 14.4 t ha-1 or 53% higher than the control (without NPK). Meanwhile, growing Trisula was not recommended for peatlands. [ABSTRACT FROM AUTHOR]

We grew three yellow Camellia species (the calcifuge C. nitidissima and C. tunghinensis, and the calcicole C. pubipetala) in acidic and calcareous soils for 7 months and assessed their photosynthetic physiological characteristics, growth performance, and element concentrations in this developmental context. The calcifuge C. nitidissima and C. tunghinensis species exhibited poor growth with leaf chlorosis, growth stagnation, and root disintegration in calcareous soils, and with their Pn, Gs, Tr, Fv/Fm, ΦPSII, ETR, qP, leaf Chla, Chlb, and Chl(a + b) concentrations, and root, stem, leaf, and total biomass being significantly lower when grown in calcareous soils relative to in acidic soils. In contrast, the calcicole C. pubipetala grew well in both acidic and calcareous soils, with few differences in the above parameters between these two soil substrates. The absorption and/or transportation of nutrient elements such as N, K, Ca, Mg, and Fe by the two calcifuge Camellia species plants grown in calcareous soils were restrained. Soil type plays a major role in the failure of the two calcifuge Camellia species to establish themselves in calcareous soils, whereas other factors such as competition and human activity are likely more important limiting factors in the reverse case. This study furthers our understanding of the factors influencing the distribution of these rare and endangered yellow Camellia species, allowing for improved management of these species in conservation projects and horticultural production. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) contamination in agricultural soils is a common issue, posing health risks as it enters the human body through the food chain. Commonly used phosphate fertilizers (PFs) not only provide essential phosphorus (P) nutrients to crops but also serve as P-containing materials for immobilizing heavy metals (HMs) like Cd in soils. Therefore, understanding the passivation effects of PFs on soil Cd and their potential influencing factors is crucial for mitigating soil Cd pollution. In this study, the impact of multi-crop applications (75 mg P kg−1, 150 mg P kg−1) of four kinds of PFs on reducing soil Cd toxicity and decreasing Cd accumulation in spinach was investigated. The results indicated that under the low application rate (75.0 mg P kg−1), all PFs could passivate Cd, and CMP demonstrated the most effective passivation of Cd. However, under the high application rate (150 mg P kg−1), the immobilization effect diminished or even activated Cd. Among the different types of PFs, CMP application alleviated soil acidification and significantly reduced soil-available Cd, showing the best performance in promoting spinach growth and Cd inhibition. These results suggest that PF application in Cd-contaminated soils affects spinach growth and Cd accumulation, with soil pH, available phosphorus (AP), and Cd dynamics being crucial; moreover, low-P, micronutrient-rich, alkaline PFs like CMP optimize spinach yields and minimize Cd uptake, and excessive application of soluble PFs decreases pH, increases Cd mobility, and poses health risks, suggesting a need for balanced fertilizer use.

Aluminum (Al), a non-essential metal for plant growth, exerts significant phytotoxic effects, particularly on root growth. Anthropogenic activities would intensify Al’s toxic effects by releasing Al3+ into the soil solution, especially in acidic soils with a pH lower than 5.5 and rich mineral content. The severity of Al-induced phytotoxicity varies based on factors such as Al concentration, ionic form, plant species, and growth stages. Al toxicity leads to inhibited root and shoot growth, reduced plant biomass, disrupted water uptake causing nutritional imbalance, and adverse alterations in physiological, biochemical, and molecular processes. These effects collectively lead to diminished plant yield and quality, along with reduced soil fertility. Plants employ various mechanisms to counter Al toxicity under stress conditions, including sequestering Al in vacuoles, exuding organic acids (OAs) like citrate, oxalate, and malate from root tip cells to form Al-complexes, activating antioxidative enzymes, and overexpressing Al-stress regulatory genes. Recent advancements focus on enhancing the exudation of OAs to prevent Al from entering the plant, and developing Al-tolerant varieties. Gene transporter families, such as ATP-Binding Cassette (ABC), Aluminum-activated Malate Transporter (ALMT), Natural resistance-associated macrophage protein (Nramp), Multidrug and Toxic compounds Extrusion (MATE), and aquaporin, play a crucial role in regulating Al toxicity. This comprehensive review examined recent progress in understanding the cytotoxic impact of Al on plants at the cellular and molecular levels. Diverse strategies developed by both plants and scientists to mitigate Al-induced phytotoxicity were discussed. Furthermore, the review explored recent genomic developments, identifying candidate genes responsible for OAs exudation, and delved into genome-mediated breeding initiatives, isolating transgenic and advanced breeding lines to cultivate Al-tolerant plants.

Background and aims: There are controversies in the literature regarding the edaphic factors that may interfere with the occurrence of Rhizoctonia root rot in soybean, a disease caused by the soilborne fungus Rhizoctonia solani. The objective of this study was to determine which chemical and physical soil attributes are associated with the occurrence of Rhizoctonia root rot in soybean grown in a subtropical environment. Methods: Four fields with history of disease occurrence were selected, according to their soil class variability (Acrisol, Cambiol Ta, Cambisol Tb and Nitisol), in the municipality of Soledade, Rio Grande do Sul, Brazil. In each field, soil samples were collected in the 0–10 cm layer, inside and outside the bare patch with Rhizoctonia root rot, and in four repetitions for analysis of chemical and physical attributes. Results: The exchangeable contents and the saturation by aluminum and the extractable copper content were higher in the patch with the disease. On the other hand, the indicators of lower soil acidity (higher exchangeable calcium and magnesium content, pH value and base saturation) were the ones most associated with the area outside the patch. There was some association with soil texture regarding high clay content where the disease has been observed. Conclusion: Chemical attributes related to acidic soils are the ones most associated to the incidence of Rhizoctonia root rot in soybean grown in a subtropical environment in southern Brazil. [ABSTRACT FROM AUTHOR]

Potentiometric titration in a fast and simultaneously high-resolution modality was proposed for the identification and quantification of protolytic groups of variable strength at the surface of primary soil particles. The method is implemented by titrimetric data processing as multicomponent spectra (pKa spectrotitrimetry). Due to the high resolution, the error of acidity-constant assessment (3–5%) is lower, compared to existing approaches; due to the fast titration, the effect of soil hydrolysis is minimized. The soil profiles for acidic Retisols (podzolic soils)—under a spruce crown and in the intercrown space—were studied. These soils, which have similar bulk properties and genesis but developed under different plant covers, were distinguished by pKa spectral features at 4–5; 5.5–6.5; 6.5–8.5; 7.5–8.5; and 9–10, as well as total group concentrations. Differences in acidic and basic-group distribution (carboxyl groups, amorphous aluminosilicates, carbonate species, amino groups, soluble (poly)phenolic compounds, phospholipids) and Al and Fe complex compounds within the same soil profiles and between two Retisols were found and quantified. The acidity constants and group concentrations found by pKa spectrotitrimetry were compared with conventional soil-composition indicators (total organic carbon, oxalate-soluble Fe and Al, and phosphorus), using principal component analysis. The main correlations are between the concentrations of oxalate-soluble Al and groups with pKa values of 5.0–6.5 and 8.5; oxalate-soluble Fe and pKa values of 9.0–10.0; and P2O5 and pKa values of 4.0–6.0 and 6.5–8.5. The method provides a set of major acidity values without a priori information on a soil sample and can be used for screening and identifying similar soils.

Phosphorus availability is a serious problem for plants growing and grown in acidic soils of bogs, poor in macronutrients. The application of phosphorus fertilizers to such soils is unprofitable because of the physical and chemical properties of these soils, where phosphate is firmly bound to organic and inorganic compounds and becomes inaccessible to plants. Plants of the Vaccinium genus both from natural stands and commercial plantations may suffer from phosphorus deficiency, so they need to have a number of adaptations that allow them to efficiently extract phosphorus. This review addresses the following issues in relation to plants of the Vaccinium genus: sources of phosphorus for plants; the release of phosphate ions from soil components; the transport of phosphate ions into plants; and the importance of mycorrhiza in supplying phosphorus to plants. Thus, we sought to draw researchers’ attention to sources and routes of phosphorus supply of plants of the Vaccinium genus and its unexplored aspects.

Due to its adsorption with aluminum and iron hydroxides, phosphorus viability is low in acidic soils; thus, the aim of this study was to isolate and identify bacteria from the rhizosphere of four legumes growing in acidic soils of the Cumbaza Sub-basin, San Martín, Peru, as well as to characterize their ability to solubilize aluminum phosphate and iron phosphate. The isolation process was conducted on TSA medium and the isolates were classified based on their origin and morphocolonial characteristics, with the bacillary shape being the most frequent, followed by cocci. To assess the solubilization of aluminum and iron phosphates, the liquid medium GELP was employed. Sixteen strains were selected, among which three stood out for their effectiveness in solubilizing AlPO4 (Sfcv-098-02, 22.65 mg L−1; Sfc-093-04, 26.50 mg L−1; and Sfcv-041-01-2, 55.98 mg L−1) and one for its ability to solubilize FePO4 (Sfcr-043-02, 32.61 mg L−1). These four strains were molecularly characterized, being identified as Enterobacter sp., Pseudomonas sp., and Staphylococcus sp. Additionally, a decrease in pH was observed in the reactions, with values ranging from 5.23 to 3.29, which enhanced the phosphate of solubilization. This suggests that the selected bacteria could be used to improve phosphorus availability in agricultural soils.

Soil acidity is a serious problem in agricultural lands as it directly affects the soil, crop production, and human health. Soil acidification in agricultural lands occurs due to the release of protons (H+) from the transforming reactions of various carbon, nitrogen, and sulfur-containing compounds. The use of biochar (BC) has emerged as an excellent tool to manage soil acidity owing to its alkaline nature and its appreciable ability to improve the soil’s physical, chemical, and biological properties. The application of BC to acidic soils improves soil pH, soil organic matter (SOM), cation exchange capacity (CEC), nutrient uptake, microbial activity and diversity, and enzyme activities which mitigate the adverse impacts of acidity on plants. Further, BC application also reduce the concentration of H+ and Al3+ ions and other toxic metals which mitigate the soil acidity and supports plant growth. Similarly, soil salinity (SS) is also a serious concern across the globe and it has a direct impact on global production and food security. Due to its appreciable liming potential BC is also an important amendment to mitigate the adverse impacts of SS. The addition of BC to saline soils improves nutrient homeostasis, nutrient uptake, SOM, CEC, soil microbial activity, enzymatic activity, and water uptake and reduces the accumulation of toxic ions sodium (Na+ and chloride (Cl-). All these BC-mediated changes support plant growth by improving antioxidant activity, photosynthesis efficiency, stomata working, and decrease oxidative damage in plants. Thus, in the present review, we discussed the various mechanisms through which BC improves the soil properties and microbial and enzymatic activities to counter acidity and salinity problems. The present review will increase the existing knowledge about the role of BC to mitigate soil acidity and salinity problems. This will also provide new suggestions to readers on how this knowledge can be used to ameliorate acidic and saline soils. [ABSTRACT FROM AUTHOR]

Biochar is important for soil improvement, fertilizer innovation, and greenhouse gas reduction. In this paper, Mg-modified biochar was prepared from rice and corn straw and mixed with soil at a 1% (w/w) addition in an indoor soil simulation experiment to study the effect of Mg-modified biochar on the chemical properties of acidic soil. The results showed that the addition of Mg-modified biochar reduced soil acidity and improved soil fertility. Compared with the control group, the Mg-modified biochar treatment significantly increased the concentrations of available potassium, available phosphorus, total phosphorus, organic carbon and exchangeable calcium and magnesium in the soil, and effectively increased the concentration of total nitrogen. Rice straw Mg-modified biochar treatment was more effective in increasing the soil-available potassium, available phosphorus, total phosphorus and exchangeable magnesium concentration, while corn straw Mg-modified biochar was more effective in increasing the soil organic carbon and exchangeable calcium concentration. In addition, the high pyrolysis temperature of Mg-modified biochar was more effective in promoting the soil-available potassium, available phosphorus and total nitrogen concentration, while the low pyrolysis temperature of Mg-modified biochar was more effective in promoting soil alkaline nitrogen, exchangeable calcium and magnesium. [ABSTRACT FROM AUTHOR]

The application of nitrogen (N) fertilizers and liming (CaCO3) to improve soil quality and crop productivity are regarded as effective and important agricultural practices. However, they may increase greenhouse gas (GHG) emissions. There is limited information on the GHG emissions of tropical soils, specifically when liming is combined with N fertilization. We therefore conducted a full factorial laboratory incubation experiment to investigate how N fertilizer (0 kg N ha−1, 12.5 kg N ha−1 and 50 kg N ha−1) and liming (target pH = 6.5) affect GHG emissions and soil N availability. We focussed on three common acidic soils (two ferralsols and one vertisol) from Lake Victoria (Kenya). After 8 weeks, the most significant increase in cumulative carbon dioxide (CO2) and nitrous oxide (N2O) fluxes compared with the unfertilized control was found for the two ferralsols in the N + lime treatment, with five to six times higher CO2 fluxes than the control. The δ13C signature of soil‐emitted CO2 revealed that for the ferralsols, liming (i.e. the addition of CaCO3) was the dominant source of CO2, followed by urea (N fertilization), whereas no significant effect of liming or of N fertilization on CO2 flux was found for the vertisol. In addition, the N2O fluxes were most significantly increased by the high N + lime treatment in the two ferralsols, with four times and 13 times greater N2O flux than that of the control. No treatment effects on N2O fluxes were observed for the vertisol. Liming in combination with N fertilization significantly increased the final nitrate content by 14.5%–39% compared with N fertilization alone in all treatment combinations and soils. We conclude that consideration should be given to the GHG budgets of agricultural ferralsols since liming is associated with high liming‐induced CO2 and N2O emissions. Therefore, nature‐based and sustainable sources should be explored as an alternative to liming in order to manage the pH and the associated fertility of acidic tropical soils. [ABSTRACT FROM AUTHOR]

Extremely acidic soils have low pH, high concentration of exchangeable Al3+ and low cation exchange capacity (CEC) that cause severe growth for most plants. The study was conducted in the soil laboratory of the Indonesian Vegetable Research Institute, Lembang, from June to August 2019. A randomised complete block design with seventeen treatments, three replications, and three incubation times (3, 30 and 60 days) was deployed to assess the effect of rates of soil amendments, namely 5 to 30 t liming materials ha-1, 5 to 20 t rice husk biochar ha-1, and 5 to 20 t zeolite ha-1 on extremely acidic soils. The results showed that lime materials, i.e., lime, agriculture limestone, and hydrated lime had a similar effect on increasing soil pH and reducing exchangeable Al3+. Calcium super seemed more effective in increasing soil pH and reducing exchangeable Al3+ than local lime due to the high CCE value. However, there was no significant response to the highest rice husk biochar and zeolite rate on soil pH and exchangeable Al3+. Rice husk biochar increased the concentration of K+ and zeolite raised the concentration of Na+. However, the effect was minimal. About 3 t lime ha-1 or 2.5 t calcium super ha-1 or equivalent to 1.5 to 2 times exchangeable Al3+ is required to obtain the soil pH target of 4.8, where the exchangeable Al3+ was less than 0.5 cmol(+) kg-1.

Glycophyte biomass − derived biochars have proven to be effective in the amelioration of acidic soil. However, there is scarce information on the characteristics and soil amelioration effects of halophyte-derived biochars. In this study, a typical halophyte Salicornia europaea, which is mainly distributed in the saline soils and salt-lake shores of China, and a glycophyte Zea mays, which is widely planted in the north of China, were selected to produce biochars with a pyrolysis process at 500 °C for 2 h. S. europaea-derived and Z. mays-derived biochars were characterized in elemental content, pores, surface area, and surface functional groups, and then by using a pot experiment their potential utilizable value as acidic soil conditioner was evaluated. The results showed that compared with Z. mays-derived biochar, S. europaea-derived biochar displayed higher pH, ash contents, base cations (K+, Ca2+, Na+, and Mg2+) contents and exhibited more larger surface area and pore volume than Z. mays-derived biochar. Both biochars had abundant oxygen-containing functional groups. Upon treating the acidic soil, the pH of acidic soil was increased by 0.98, 2.76, and 3.36 units after the addition of 1%, 2%, and 4% S. europaea-derived biochar, while it was increased only by 0.10, 0.22, and 0.56 units at 1%, 2%, and 4% Z. mays-derived biochar. High alkalinity in S. europaea-derived biochar was the main reason for the increase of pH value and base cations in acidic soil. Thus, application of halophyte biochar such as S. europaea-derived biochar is an alternative method for the amelioration of acidic soils. [ABSTRACT FROM AUTHOR]

The use of biochar and lime (CaO) is a common approach to mitigating soil acidification. However, little is known about how biochar and lime amendments impact N2O emissions and potential microbial mechanisms. We conducted a 45-day microcosm incubation experiment to examine N2O emission and associated functional guilds to biochar and lime amendment in an acidic tea plantation soil. Results show that lime and biochar treatments significantly reduced cumulative N2O emissions by 49.69% and 63.01%, respectively, while significantly increasing cumulative CO2 emissions by 27.51% and 19.35%, respectively. Additionally, lime and biochar treatments significantly decreased the abundances of bacterial nirK, nirS, nosZ and fungal nirK genes, while increasing that of the ammonia-oxidizing bacteria (AOB) and the complete ammonia-oxidizing bacteria (comammox) amoA genes. The stimulated or inhibitory effects of biochar on functional genes abundances were higher than lime. The N2O emission rate was positively linked with the abundance of the fungal nirK gene but was negatively correlated with AOB and comammox amoA genes abundances. The random forest and linear regression analysis revealed that fungal denitrifiers were the most important predictors of N2O emissions. Lime and biochar amendments reduced the alpha diversity and altered the community composition of nirK-harboring fungal denitrifiers. Ascomycota was the dominant fungal denitrifiers belonging to the families Nectriaceae, Aspergillaceae, and Chaetomiaceae, and the relative abundances of genera Chaetomium, Penicillium and Fusarium were positively correlated with N2O emissions. Overall, our findings suggest that biochar is more effective than lime in reducing N2O emissions, and this is likely due to the powerful effects it has on community traits of nirK-harboring fungal denitrifiers. [ABSTRACT FROM AUTHOR]

The aim of this study is to determine the effects of structural soil restoration on the buffering capacities of these soils, their productivity, and the efficiency of their use as a basis for sustainable management. Based on a review of literature sources and our own experimental research, the proposed article shows the possibility of improving the buffering capacities of sod-podzolic cohesive sandy soils through the use of structural amelioration as an effective measure to protect them from degradation and ensure their resilience to climate change. The use of structural ameliorants (clay and peat) in the studied soils improves the granulometric composition, has a positive effect on the pH-buffering capacities, and contributes to optimizing the moisture capacity of soil. It was found that the efficiency of the application of structural amelioration on sod-podzolic cohesive sandy soils increases significantly with the local application method (e.g., clay in a dose of 10 t/ha or a combined application of clay in a dose of 2 t/ha with lowland peat in a dose of 3 t/ha). The largest yield increase in winter wheat (27.2%) was achieved by the local application of 2 t/ha of clay combined with peat in a dose of 3 t/ha. [ABSTRACT FROM AUTHOR]

Ongoing rapid climatic changes are expected to modify the structure, composition, and functioning of forest ecosystems. Studying the influence of such changes on biogeochemical processes is thus crucial for a fuller understanding of forest response to climate change. In a temperate forest of Quebec, Canada, we emulated climate change by warming the acidic, nutrient-poor, and dry soils of two mixedwoods by 3 to 4 °C using heating cables. Leaf-litter mass loss of the local red maple, sugar maple, large-tooth aspen, and American beech were monitored to assess the ability of these tree species to condition boreal soils in the context of their northward migration under climate change. We hypothesized that decomposition rates of all leaf-litter types would be decreased equally by warming due to a drying effect of the soil and its surface, which is detrimental to microbial biomass and activity. Our results suggest differences in decomposition rates between tree species as follows: sugar maple > red maple ≥ American beech = large-tooth aspen. There was no indication of a slower turnover in these marginal soils compared to other studies conducted on typical hardwood soils. Moreover, no difference in litter mass loss was detected between treatments, likely due to a drying effect of the soil warming treatment. Results imply that climate change has a marginal influence on leaf-litter dynamics of temperate tree species on soils that are typical of the boreal forest. However, some variables that could play an important role on litter decomposition in the context of climate change were not measured (e.g., plant phenology, understory composition and density, microbes) and thus, uncertainties remain. The soil drying effect by warming also needs to be further documented and modeled. The study year was characterized by significant periods of water stress but was not considered an exceptional year in that regard. It would be relevant to test for leaf-litter dynamics during dry and wet summers and verify again our initial hypothesis of decreased leaf-litter decomposition rates due to soil warming/drying. [ABSTRACT FROM AUTHOR]

Nonparametric tests can often be applied in many important problems, since they hold under more general conditions than parametric tests. In this work we propose a nonparametric test for grouping of factor levels. We apply that test to a cocoa breeding experiment in Ghana, in which twelve cocoa varieties were compared. There were three groups of varieties, two of which have a common ascendant, and we intend to test if this grouping is significant. The cocoa breeding experiment was carried out in four types of soils. All these types of soils are acidic, so resistance to low pH is an important goal of the plant breeding. The obtained results suggest that the grouping is significant for the most acidic soil. [ABSTRACT FROM AUTHOR]

Copper-contained products that are widely employed yearly in viticulture for vine disease management, lead to Cu accumulation in topsoil creating an increased risk for land workers and for leaching and/or uptake of Cu by plants, especially in acidic soils where Cu mobility is higher. In this study, the impact of two biochar types on Cu distribution and redistribution in fractions was evaluated in four acidic vineyard soils in relation to incubation time. The two biochars were derived from sewage sludge (SG) and olive tree prunings (OL). Soils (control) and biochar-amended soils with application rate of 20 % (w/w) were spiked with CuCl2 (160 mg kg−1) and incubated in the laboratory at ambient temperature 22 ± 5 °C. After 1, 3, 7, 15, 36, and 90 days of incubation, modified BCR sequential extraction procedure was used to determine Cu distribution in the four soil chemical phases and to examine potential Cu redistribution between these fractions both in soils and in amended soils with biochars. Results show that biochar amendment affects Cu distribution in different soil fractions. In SG treatment, from the 1st and up to 36th incubation day, both exchangeable and reducible Cu fractions decreased, while oxidizable Cu increased, in relation to control soils. At 90th incubation day, a redistribution of Cu was observed, mainly from the oxidizable to the residual fraction. In OL treatment, during the first 36 incubation days exchangeable and oxidizable Cu slightly increased, while reducible Cu decreased. At the 90th incubation day the higher percentage of Cu was extracted from the residual fraction, but exchangeable Cu was present in remarkable quantities in the three of the four studies soils. SG application in the studied soils highly restricted the availability of added Cu promoting Cu-stable forms thus reducing the environmental risk while OL did not substantially reduce Cu available fraction over the experimental incubation period. Fourier transformation infrared analysis (FTIR) provided convincing explanations for the different behavior of the two biochar types. [ABSTRACT FROM AUTHOR]

Purpose: The compounds 1-octyne and 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO) are frequently used as nitrification inhibitors for ammonia-oxidizing bacteria (AOB) and archaea (AOA), respectively, but their influence on comammox Nitrospira remains unclear. In this study, we examine how will 1-octyne and PTIO influence AOA, AOB, and comammox Nitrospira in an acidic Ultisol. The results will provide guidance for the nitrification inhibitor selections in the relevant research and field management practices. Materials and methods: We carried out a microcosm experiment using acetylene, 1-octyne, and PTIO as nitrification inhibitors to investigate their effects on ammonia oxidizers, especially comammox Nitrospira. The abundance of ammonia oxidizers was determined by real-time quantitative PCR while the community structure of comammox Nitrospira was examined by Illumina MiSeq sequencing. Results and discussion: Acetylene, 1-octyne, and PTIO significantly reduced the net nitrification rate, with a more pronounced effect observed for acetylene and 1-octyne amendments. The addition of 1-octyne suppressed the growth of comammox Nitrospira clade A, indicating that 1-octyne was not an exclusive inhibitor for AOB in the acidic Ultisols. Moreover, PTIO reduced the abundance of AOB and comammox Nitrospira clade A, rather than that of AOA, suggesting that AOB and comammox Nitrospira were more sensitive than AOA to the PTIO inhibition in the tested soils. Acetylene, 1-octyne, and PTIO did not show observed changes to comammox Nitrospira community structure. Conclusions: We provide novel evidence that 1-octyne and PTIO can significantly inhibit the growth of comammox Nitrospira, but have no significant effects on their community structure in the acidic Ultisols. Our findings have implications for proper selection of nitrification inhibitors 1-octyne and PTIO in both laboratory experiments and field practices. [ABSTRACT FROM AUTHOR]

Land degradation is one of the most important factors responsible for the alarming situation of food security, human health, and socioeconomic development in the country. Currently, 120.7 M ha of land in the country is affected by land degradation, out of which 85.7 M ha of land is affected by soil erosion caused by water and wind. Moreover, physical, chemical, and biological degradation are the major forms of land degradation in the country. Deforestation or tree cover loss (2.07 M ha) from 2001 to 2021, intensive rainfall (>7.5 mm ha−1), uncontrolled grazing (5.65 M ha), indiscriminate use of fertilizers (32 MT year−1), and shifting cultivation (7.6 M ha) are other major factors that further aggravate the process of land degradation. In order to alleviate the problem of land degradation, numerous agroforestry technologies have been developed after years of research in different agroclimatic zones of the country. The major agroforestry systems observed in the country are agri-horticulture, silvipasture, and agri-silviculture. This review indicates the potential of agroforestry in enhancing carbon sequestration (1.80 Mg C ha−1 year−1 in the Western Himalayan region to 3.50 Mg C ha−1 year−1 in the island regions) and reduced soil loss and runoff by 94% and 78%, respectively, in Northeast India. This can be concluded that the adoption of the agroforestry system is imperative for the rehabilitation of degraded lands and also found to have enough potential to address the issues of food, environmental, and livelihood security. This review’s findings will benefit researchers, land managers, and decision-makers in understanding the role of agroforestry in combating land degradation to enhance ecosystem service in India and planning suitable policies for eradicating the problem effectively.

Microbes play an important role in rhizosphere phosphorus (P) activation and root P absorption in low P-available soils. However, the responses of the rhizosphere microbial community to P input and its effects on P uptake by tea plants have not been widely reported. In this study, the high-throughput sequencing of the 16S rRNA gene and the ITS2 region was employed to examine the responses of tea rhizosphere microbiomes to different P input rates (low-P, P0: 0 mg·kg−1 P; moderate-P, P1: 87.3 mg·kg−1 P; high-P, P2: 436.5 mg·kg−1 P). The results showed that the P input treatments significantly reduced the soil C: N ratio and C: P ratio compared to the P0 treatment (p < 0.05). Moreover, the P2 treatment significantly increased the soil available P, plant biomass and P content of the tea plant compared to the P0 and P1 treatments (p < 0.05). Both bacterial and fungal communities revealed the highest values of alpha diversity indices in the P1 treatment and the lowest in the P2 treatment. The dominant phyla of the bacterial community were Proteobacteria, Actinobacteria and Acidobacteria, while in the fungal community they were Ascomycota and Mortierellomycota. In addition, P input enriched the relative abundance of Actinobacteria and Proteobacteria but decreased the relative abundance of Acidobacteria. The Mantel correlation analysis showed that the fungal community was influenced by P input, whereas bacterial community was affected by the soil TC and C: N ratio. Furthermore, the P input treatments enhanced the TCA cycle, amino and nucleotide glucose metabolism, starch and sucrose metabolism, and phosphotransferase system expression, which could promote C and N cycling. On the contrary, the P input treatments negatively affected the growth of arbuscular mycorrhizal fungi. The PLS-PM model revealed that the rhizosphere bacterial and fungal communities, respectively, negatively and positively affected the P content by affecting the biomass. Meanwhile, rhizosphere microbial function profiles affected the P content of tea plants directly and positively. In summary, moderate P input favors the rhizosphere microbial diversity and functions in the short-term pot experiment. Therefore, we suggest that moderate P input should be recommended in practical tea production, and a further field test is required. [ABSTRACT FROM AUTHOR]

Extremely acidic soils have low pH, high concentration of exchangeable Al3+ and low cation exchange capacity (CEC) that cause severe growth for most plants. The study was conducted in the soil laboratory of the Indonesian Vegetable Research Institute, Lembang, from June to August 2019. A randomised complete block design with seventeen treatments, three replications, and three incubation times (3, 30 and 60 days) was deployed to assess the effect of rates of soil amendments, namely 5 to 30 t liming materials ha-1, 5 to 20 t rice husk biochar ha-1, and 5 to 20 t zeolite ha-1 on extremely acidic soils. The results showed that lime materials, i.e., lime, agriculture limestone, and hydrated lime had a similar effect on increasing soil pH and reducing exchangeable Al3+. Calcium super seemed more effective in increasing soil pH and reducing exchangeable Al3+ than local lime due to the high CCE value. However, there was no significant response to the highest rice husk biochar and zeolite rate on soil pH and exchangeable Al3+. Rice husk biochar increased the concentration of K+ and zeolite raised the concentration of Na+. However, the effect was minimal. About 3 t lime ha-1 or 2.5 t calcium super ha-1 or equivalent to 1.5 to 2 times exchangeable Al3+ is required to obtain the soil pH target of 4.8, where the exchangeable Al3+ was less than 0.5 cmol(+) kg-1. [ABSTRACT FROM AUTHOR]

Extreme environments and plants thriving in them, known as extremophytes, offer promising platforms for studying the diverse adaptive mechanisms that have evolved in plants. However, research on adaptation to extreme environments is still limited to those environments where model species or their relative can survive. Fumarole fields, an extreme environment often overlooked, are characterized by multi-hazardous abiotic stressors, including atmospheric contamination (high concentration of H2S, SO2, and CO2), high soil temperature (~60℃), and strong soil acidification (pH=2-3). These conditions make fumarole fields a rich source for studying stress tolerance mechanisms in plants. In this review, we highlight the recent ecological, physiological, and genomic advances involved in fumarole field adaptation, and discuss the forward avenues. The studies outlined in this paper demonstrate that the extreme levels of abiotic stressors found in fumarole fields make them unparalleled field laboratories for studying the unknown stress tolerance mechanisms, warranting further genomic assessments. Some studies succeeded in identifying genes associated with fumarole field adaptation and shedding light on evolutionary implications; however, they have also encountered challenges such as limited genome resources and high genetic differentiation from related species and/or neighboring populations. To overcome such difficulties, we propose integrating ecophysiological and genomic approaches, drawing from the recent studies in other extreme environments. We expect that further studies in the fumarole fields will contribute to broadening our general knowledge of the limits of life., (© The Author(s) 2024. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site–for further information please contact journals.permissions@oup.com.)

Biochar is important for soil improvement, fertilizer innovation, and greenhouse gas reduction. In this paper, Mg-modified biochar was prepared from rice and corn straw and mixed with soil at a 1% (w/w) addition in an indoor soil simulation experiment to study the effect of Mg-modified biochar on the chemical properties of acidic soil. The results showed that the addition of Mg-modified biochar reduced soil acidity and improved soil fertility. Compared with the control group, the Mg-modified biochar treatment significantly increased the concentrations of available potassium, available phosphorus, total phosphorus, organic carbon and exchangeable calcium and magnesium in the soil, and effectively increased the concentration of total nitrogen. Rice straw Mg-modified biochar treatment was more effective in increasing the soil-available potassium, available phosphorus, total phosphorus and exchangeable magnesium concentration, while corn straw Mg-modified biochar was more effective in increasing the soil organic carbon and exchangeable calcium concentration. In addition, the high pyrolysis temperature of Mg-modified biochar was more effective in promoting the soil-available potassium, available phosphorus and total nitrogen concentration, while the low pyrolysis temperature of Mg-modified biochar was more effective in promoting soil alkaline nitrogen, exchangeable calcium and magnesium.

Background and aims: Liming is widely used to alleviate soil acidity worldwide. However, the vast majority of studies with liming are restricted to agricultural systems that incorporate lime into the soil, not considering its effects as surface applications. Although liming effects on soil fertility and crop yield are well understood, there are few studies that elucidate the role of soil improvements in the established crop physiology and the revenue in lime-amended soils, especially when cultivated in regions prone to agroclimatic risks. Here, we address the effects of surface liming, for three growing seasons (2017–2019) subsequent to the lime treatment (2016), on soil fertility, root growth, crop nutrition, photosynthetic pigment concentrations, gas exchange parameters and production costs of maize cultivated in a tropical region on an acidic soil with low water regime. Methods: The treatments consisted of four dolomitic lime doses applied to the soil surface as follows: i) control (untreated soil), ii) half the recommended dose (½ RD), iii) full recommended dose (1 RD) and iv) twice the recommended dose (2 RD). Results: Surface liming increased soil fertility, and higher doses provided better results. Ca2+ and Mg2+ concentrations increased at greater depths under higher lime doses, directly influencing maize root growth. Even under low water availability, also in the driest year of 2018, this liming induced improvement of growing conditions and increased growth was observed'. Maize grown under lime at 2 RD exhibited better nutrition, improved chlorophylls concentration, photosynthetic parameters and water use efficiency. As a result, both shoot growth and grain yield also increased. Net profit in the first growing season was higher in 1 RD, whereas in the two following growing seasons the application of 2 RD resulted in higher revenue. Conclusions: Increased water use efficiency, chlorophyll and photosynthesis were the main physiological traits regulating the growth and yield of maize plants in response to lime supply. Additionally, root development was favoured in the entire soil profile, mainly in deeper layers, after improvements on soil fertility by cascading effects of liming. These results were more prominent in 2RD lime-amended soil, which also resulted in greater net profit over the 3 years studied. [ABSTRACT FROM AUTHOR]

During the past decades, extensive nitrogen fertilization and acid deposition have greatly contributed to soil acidification in agroecosystems. Liming, the addition of calcium- and magnesium-rich material to soil, is an effective management strategy used to improve fertility and productivity of agricultural soils degraded by acidification. Nitrification plays a central role in nitrogen (N) availability in agroecosystems and contributes to soil acidification. However, little is known regarding the effects of liming on this process and microbial populations that drive it. Here, we investigated population dynamics and activity of ammonia oxidizers in response to a 2-year liming field trial in acidic soils received long-term fertilization with chemical N fertilizers and short-term lime amendment in microcosm incubations. Our results showed that activity, abundance and population structure of both ammonia-oxidizing archaea (AOA) and bacteria (AOB) were sensitive to liming in fertilized acidic soils. AOB abundance and potential nitrification rates increased in field plots subjected to liming, whereas the opposite was observed for AOA. In microcosm incubations, AOA abundance increased progressively over 60 days, namely under low CaO levels, whereas AOB abundance was greatly stimulated only during the first week under high CaO levels. 13CO2-SIP-DNA experiments further supported that AOA were the most active ammonia oxidizers in fertilized field soils. However, in N-fertilized soils freshly amended with CaO, only autotrophic growth of AOB was observed after seven days, but not after 30 days when growth of AOA was observed. Taken together, our results indicated that both AOA and AOB play a role in nitrification following liming in fertilized acidic soils, likely through selection of better adapted clades of organisms. Although AOA were likely the main drivers of nitrification in these soils in the long-term, liming stimulated AOB activity in the short-term.

Soil acidification and increased bioavailability of Ni are problems that affect agricultural soils. This study aims to compare the effects of both lime and biochar from corn stover in soil acidity correction, improving soil physicochemical properties and soil re-acidification resistance. As well as assesseing the impacts on human health risk caused by bioavailability of nickel. A greenhouse pot experiment was conducted for 30 days to determine the effect of biochar and lime on soil physicochemical properties and nickel bioavailability. Afterwards, a laboratory test was carried out to determine the repercussions of both amendments on soil resistance to re-acidification and re-mobilization of nickel. Human health risk was determined using nickle bioavailable concentration. Overall, the results of this study showed that biochar application significantly reduced soil acidity from 8.2 ± 0.8 meq 100 g−1 to 1.9 ± 0.3 meq 100 g−1, this reduction markedly influenced the bioavailability of nickel, which decreased significantly. Moreover, soil physicochemical properties and soil resistance to acidification were improved. Furthermore, biochar significantly reduced human health risk compared to lime application, even under a re-acidification scenario. It was possible to verify that Ni immobilization in the soil was increased when biochar was used. Soil Ni immobilization is associated with co-precipitation and chemisorption. Hence, it was demonstrated that biochar is more effective than lime in reducing soil acidity and remedying nickel-contaminated agricultural soils.

ABSTRACT Soil acidification and Phosphorus deficiency are major challenges to acid sensitive crop production in most of the highlands of Oromia. Study was initiated to evaluate degree of acidity related soil chemical properties and impact of lime (0, 3, 5, 7 and 9 t ha-1) rates on P sorption characteristics of acidic soil. Analysis of soil chemical properties (pH, exchangeable acidity, Aluminum saturation, available and total P, soil P-sorption characteristics and 90 days Greenhouse incubation were employed using standard laboratory procedures to evaluate effect of lime rates on acidity related chemical properties, P-sorption characteristics and percent increment of available p before and after incubation. Result of soil pH, revealed that all soils from studied sties fallen in very strongly acidic (4.63-4.89) media. Values of soil exchangeable acidity, percent acid saturation and Al saturation of soils ranged from 1.43-2.49cmol (+) kg-1 soil, 5.36-9.37% and 3.57-6.28%, respectively. Available P before liming varied from 7.07-8.02 ppm and qualifying low range. However, due to application of lime, there was decrease of average percent total p- sorption of soils and ranged from 93% in the control to 57% at 9 t ha-1 lime rates. Moreover, percent increment of average available P ranges from 7.2% in the control to 43.6% for 9 t ha-1 lime. The positive values of R2 values of Langmuir regression equation indicated, there was strong positive relationship of increment of P availability with lime rates incubated soils. Therefore, attention shall be given to restore continuous cultivation of acidic soils of study sites using reclamation options.

The use of biochar and lime (CaO) is a common approach to mitigating soil acidification. However, little is known about how biochar and lime amendments impact N2O emissions and potential microbial mechanisms. We conducted a 45-day microcosm incubation experiment to examine N2O emission and associated functional guilds to biochar and lime amendment in an acidic tea plantation soil. Results show that lime and biochar treatments significantly reduced cumulative N2O emissions by 49.69% and 63.01%, respectively, while significantly increasing cumulative CO2 emissions by 27.51% and 19.35%, respectively. Additionally, lime and biochar treatments significantly decreased the abundances of bacterial nirK, nirS, nosZ and fungal nirK genes, while increasing that of the ammonia-oxidizing bacteria (AOB) and the complete ammonia-oxidizing bacteria (comammox) amoA genes. The stimulated or inhibitory effects of biochar on functional genes abundances were higher than lime. The N2O emission rate was positively linked with the abundance of the fungal nirK gene but was negatively correlated with AOB and comammox amoA genes abundances. The random forest and linear regression analysis revealed that fungal denitrifiers were the most important predictors of N2O emissions. Lime and biochar amendments reduced the alpha diversity and altered the community composition of nirK-harboring fungal denitrifiers. Ascomycota was the dominant fungal denitrifiers belonging to the families Nectriaceae, Aspergillaceae, and Chaetomiaceae, and the relative abundances of genera Chaetomium, Penicillium and Fusarium were positively correlated with N2O emissions. Overall, our findings suggest that biochar is more effective than lime in reducing N2O emissions, and this is likely due to the powerful effects it has on community traits of nirK-harboring fungal denitrifiers.

The aim of this study is to determine the effects of structural soil restoration on the buffering capacities of these soils, their productivity, and the efficiency of their use as a basis for sustainable management. Based on a review of literature sources and our own experimental research, the proposed article shows the possibility of improving the buffering capacities of sod-podzolic cohesive sandy soils through the use of structural amelioration as an effective measure to protect them from degradation and ensure their resilience to climate change. The use of structural ameliorants (clay and peat) in the studied soils improves the granulometric composition, has a positive effect on the pH-buffering capacities, and contributes to optimizing the moisture capacity of soil. It was found that the efficiency of the application of structural amelioration on sod-podzolic cohesive sandy soils increases significantly with the local application method (e.g., clay in a dose of 10 t/ha or a combined application of clay in a dose of 2 t/ha with lowland peat in a dose of 3 t/ha). The largest yield increase in winter wheat (27.2%) was achieved by the local application of 2 t/ha of clay combined with peat in a dose of 3 t/ha.