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Most conventional phosphorous (P) fertilizers are highly soluble, which favors P retention in the solid phase of the soil, and this condition hinders P availability to plants. Alternative P fertilizers, such as organominerals and struvite, have a slow release of nutrients into the soil, which in turn favors P uptake by plants; nevertheless, soil acidification caused by nitrogen (N) fertilizers can reduce P availability in the soil. In his study, we assessed the effect of N fertilizers on P availability for maize (Zea mays) grown in tropical soils with alternative P fertilizers. An experiment was set up in columns under greenhouse conditions with maize in two cultivation cycles in two soils with contrasting textures (medium and clayey textures), two N fertilizers (calcium nitrate - CN - and ammonium sulfate - AS), three P fertilizers (triple superphosphate - TSP -, organomineral - OM - and struvite - ST), and a control treatment (without addition of P and N fertilizers). At 45 days after emergence, we measured the biomass production and the N and P contents in plants to calculate fertilization efficiency as well as the soil P content. AS promoted the highest aboveground N accumulation, whereas the highest efficiency was obtained with CN. The alternative P sources did not differ in terms of P availability when combined with both N sources. Soil textures were sensitive to fertilizer combination. Further studies are needed to assess struvite interaction with other elements in the soil and the P release kinetics to plants. [ABSTRACT FROM AUTHOR]

Background: Conventional management (CM), substantial fertilization and flooding irrigation, has led to soil acidification, the decrease in soil bacterial diversity in bamboo forests. Integration of water and fertilizer management (IWF) can effectively improve the efficiency of water and fertilizer use, but its effect on soil environment, especially on microbial community, is still unclear. Methods: Here, we used next-generation high-throughput sequencing to compare soil properties and bacterial communities through different fertilization and irrigation methods under IWF and CM. Results: Compared to the control group, CM significantly reduced soil pH and bacterial diversity, while IWF improved soil nutrition status, increased soil bacterial diversity and soil pH to a level similar to the control group. Compared with CM, IWF also improved the relative abundance of beneficial bacteria and copiotrophic bacteria community in the soil, and the bacterial community in IWF was similar to CK. The structure of the bacterial community was also significantly correlated with soil organic matter, total nitrogen, hydrolyzable nitrogen, and available potassium, while soil bacterial diversity was mainly associated with soil hydrolyzable nitrogen. Conclusions: IWF can play an important role in preventing soil acidification, the loss of soil bacterial diversity, and improving the structure of the bacterial community under specific conditions. [ABSTRACT FROM AUTHOR]

The root causes of forest tree regeneration failure are difficult to resolve, although numerous studies show ungulate herbivory, soil conditions, and competition from undesirable vegetation as likely contributors. To better understand the relative importance of each issue, we conducted a 7-year manipulative experiment to assess the interactive effects of white-tailed deer (Odocoileus virginianus) herbivory, soil acidity, and competing vegetation on tree regeneration in oak–hickory forests of central Pennsylvania, USA. Outcomes depended on initial tree seedling abundance, and all three factors had significant interactions. At low initial seedling abundance, fencing resulted in the greatest increase, but all treatments had a positive effect on seedling growth and abundance. At higher initial seedling abundance, abundance failed to recover 7 years after herbicide treatment and soil pH was an important predictor. When soil pH was >4.6 from lime application, seedling growth and abundance in unfenced controls with high initial abundance was comparable to the fenced-only treatment. Competing vegetation, assumed to be a symptom of excessive, long-term deer herbivory, does not seem to be the primary factor limiting tree regeneration in our study area. Ameliorating acid deposition warrants greater consideration as a management action because it could provide long-lasting benefits compared to short-term fence installations. [ABSTRACT FROM AUTHOR]

Soil acidification due to the long-term application of nitrogenous fertilizers and the consequent impact on crop growth have been frequently reported. The effects of acidification on soil humus, charge, and microbial communities need to be studied. In this experiment, fertilizer drenching was used to simulate the effects of multiple years of fertilizer application on the black soil. The results showed that 25 years of soil acidification treatment resulted in a decrease of 8.97% in the content of stable humus and led to a decrease of 58% and 51.18% in the humic acid (HA) content and degree of humification (PQ) value in stable humus, respectively. In addition, soil acidification leads to a significant decrease in total negative charge (CEC8.2) and variable negative charge (CECv), with both decreasing by 63.28% and 88.67%, respectively, at 25 years. Acidification treatments affected both soil microbial community abundance and diversity, with a significant decrease in Acidobacteriota and Gemmatimonadota abundance and an increase in Bacteroidia abundance and Acidobacteriota abundance at 25 years. [ABSTRACT FROM AUTHOR]

Despite its rapid growth and economic success, the sustainability of the floriculture industry as it is presently conducted is debatable, due to the huge environmental impacts it initiates and incurs. Achieving sustainability requires joint efforts from all stakeholders, a fact that is often neglected in discussions that frequently focus upon economically driven management concerns. This review attempts to raise awareness and collective responsibility among the key practitioners in floriculture by discussing its sustainability in the context of soil health, as soil is the foundation of agriculture systems. Major challenges posed to soil health arise from soil acidification and salinization stimulated by the abusive use of fertilizers. The poisoning of soil biota by pesticide residues and plastic debris due to the excessive application of pesticides and disposal of plastics is another significant issue and concern. The consequence of continuous cropping obstacles are further elucidated by the concept of plant-soil feedback. Based on these challenges, we propose the adoption and implementation of several sustainable practices including breeding stress-resistant and nutrient-efficient cultivars, making sustainable soil management a goal of floriculture production, and the recycling of plastics to overcome and mitigate the decline in soil health. The problems created by flower waste materials are highlighted and efficient treatment by biochar synthesis is suggested. We acknowledge the complexity of developing and implementing the proposed practices in floriculture as there is limited collaboration among the research and operational communities, and the policymakers. Additional research examining the impacts the floriculture industry has upon soils is needed to develop more sustainable production practices that can help resolve the current threats and to bridge the understanding gap between researchers and stakeholders in floriculture. [ABSTRACT FROM AUTHOR]

The changes in soil chemical attributes in agrosilvopastoral systems after the thinning of trees are unclear. To address this gap, this study evaluated the effects of the thinning of eucalyptus hybrid Urograndis H-13 (Eucalyptus urophylla S. T. Blake × E. grandis W. Hill ex Maiden) on soil chemical fertility in an agrosilvopastoral system in an Arenic Hapludalf in Brazil. The experimental design was a randomized block with a 3 × 4 factorial design comprising three treatments (thinning of 0%, 50%, or 100% of the eucalyptus trees) and four sampling positions relative to the eucalyptus line (0, 2.0, 4.0, and 6.0 m). Six years after eucalyptus thinning, soil acidification was observed in the 0% and 50% eucalyptus thinning treatments, especially at 0 and 2 m from the eucalyptus line. Decreases in soil pH were associated with increases in the total acidity pH 7.0 (H+ + Al3+) and Al3+ content and decreases in the K+, Ca2+, and Mg2+ contents and base saturation over the soil profile (0–1.0 m). [ABSTRACT FROM AUTHOR]

Soil acidification represents a severe threat to tobacco cultivation regions in South China, exacerbating bacterial wilt caused by Ralstonia solanacearum. The comprehension of the underlying mechanisms that facilitate the restoration of rhizosphere microbial communities in “healthy soils” is imperative for ecologically managing tobacco bacterial wilt. This study focuses on acidified tobacco soils that have been subjected to continuous cultivation for 20 years. The experimental treatments included lime (L), biochar (B), and a combination of lime and biochar (L+B), in addition to a control group (CK). Utilizing rhizosphere biology and niche theory, we assessed disease suppression effects, changes in soil properties, and the co-evolution of the rhizosphere bacterial community. Each treatment significantly reduced tobacco bacterial wilt by 16.67% to 20.14% compared to the control group (CK) (p < 0.05) and increased yield by 7.86% to 27.46% (p < 0.05). The biochar treatment (B) proved to be the most effective, followed by the lime-biochar combination (L+B). The key factors controlling wilt were identified through random forest regression analysis as an increase in soil pH and exchangeable bases, along with a decrease in exchangeable acidity. However, lime treatment alone led to an increase in soil bulk density and a decrease in available nutrients, whereas both biochar and lime-biochar treatments significantly improved these parameters (p < 0.05). No significant correlation was found between the abundance of Ralstonia and wilt incidence. Nonetheless, all treatments significantly expanded the ecological niche breadth and average variation degree (AVD), enhanced positive interactions and cohesion within the community, and intensified negative interactions involving Ralstonia. This study suggests that optimizing community niches and enhancing pathogen antagonism are key mechanisms for mitigating tobacco wilt in acidified soils. It recommends using lime-biochar mixtures as soil amendments due to their potential ecological and economic benefits. This study offers valuable insights for disease control strategies and presents a novel perspective for research on Solanaceous crops. [ABSTRACT FROM AUTHOR]

Soil acidification and low nutrient availability are two major challenges facing agriculture in most regions of East Africa, resulting in aluminum toxicity and poor crop yields. The amendment of local sediments to cropland can potentially alleviate these challenges, but responses are variable. In this study, we investigated the potential of two different local sediments influenced by volcanic deposits to increase soil pH, Si and P availability and reduce Al toxicity, thereby improve barley yield. Hence, a field experiment was established in Eldoret, Western Kenya, using 1% and 3% addition by weight of two sediments in barley cultivated plots. The Baringo 3% amendment significantly increased soil pH (from 4.7 to 7.0), the available P content (from 0.01 mg g-1 to 0.02 mg g-1) and decreased the Al availability (from 3.03 mg g-1--2.17 mg g-1). This resulted in a barley yield of 4.7 t/ha (+1061%). The Nakuru 3% and Baringo 1% amendments increased yield to 2--3 t/ha, while the Nakuru 1% did not significantly increase yield. These results highlight that, from a biophysical perspective, there are natural and local opportunities to reduce soil acidification and to partly replace mineral fertilizer, but its magnitude depends on the sediment and the amendment rate. [ABSTRACT FROM AUTHOR]

Background: Crop rotation is an important agricultural practice that often affects the metabolic processes of soil microorganisms through the composition and combination of crops, thereby altering nutrient cycling and supply to the soil. Although the benefits of crop rotation have been extensively discussed, the effects and mechanisms of different crop combinations on the soil microbial community structure in specific environments still need to be analyzed in detail. Materials and methods: In this study, six crop rotation systems were selected, for which the spring crops were mainly tobacco or gramineous crops: AT (asparagus lettuce and tobacco rotation), BT (broad bean and tobacco rotation), OT (oilseed rape and tobacco rotation), AM (asparagus lettuce and maize rotation), BM (broad bean and maize rotation), and OR (oilseed rape and rice rotation). All crops had been cultivated for > 10 years. Soil samples were collected when the rotation was completed in spring, after which the soil properties, composition, and functions of bacterial and fungal communities were analyzed. Results: The results indicate that spring cultivated crops play a more dominant role in the crop rotation systems than do autumn cultivated crops. Crop rotation systems with the same spring crops have similar soil properties and microbial community compositions. pH and AK are the most important factors driving microbial community changes, and bacteria are more sensitive to environmental responses than fungi. Rotation using tobacco systems led to soil acidification and a decrease in microbial diversity, while the number of biomarkers and taxonomic indicator species differed between rotation patterns. Symbiotic network analysis revealed that the network complexity of OT and BM was the highest, and that the network density of tobacco systems was lower than that of gramineous systems. Conclusions: Different crop rotation combinations influence both soil microbial communities and soil nutrient conditions. The spring crops in the crop rotation systems had stronger dominating effects, and the soil bacteria were more sensitive than the fungi were to environmental changes. The tobacco rotation system can cause soil acidification and thereby affect soil sustainability, while the complexity of soil microbial networks is lower than that of gramineous systems. These results provide a reference for future sustainable applications of rotation crop systems. [ABSTRACT FROM AUTHOR]

Soil acidification caused by acid deposition and N fertilization can significantly affect the composition and activity of microbial communities in acidic soils. However, whether and how acidification affects soil microorganisms and microbial‐mediated carbon (C) dynamics in alkaline soils are less known. Based on a 7‐year (2016–2023) acid addition experiment in an alkaline grassland (pH > 8) on the Loess Plateau in Northwest China, we examined the effects of soil acidification on soil fungal and bacterial communities and their C metabolism. Unexpectedly, our results showed that soil acidification mainly reduced fungal diversity, rather than bacterial diversity, possibly because acidification led to soil NH4+ accumulation and decreased plant diversity. Also, soil acidification reduced forb but increased grass biomass, and enhanced root production and turnover rate. Laboratory incubation experiments showed that changes in the microbial community and soil properties jointly promoted microbial decomposition of soil organic C (SOC), with more promotion for the decomposition of labile C (i.e. glucose) (+68.4%) than recalcitrant C (i.e. tannin) (+29.1%). Synthesis. Soil acidification reduced fungal diversity and stimulated SOC decomposition in an alkaline grassland. Given that pH decline can also accelerate soil inorganic C dissolution and carbonate‐derived CO2 release, these results highlight that soil acidification can exacerbate C loss in the alkaline soils over the long term. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

The Cerrado, South America's largest savanna, has acidic, nutrient‐poor soils and its native plants thrive under these conditions. However, abandoned pastures historically undergo changes in chemical properties due to interventions like liming and fertilizer use. This favors invasive African grasses and hinders native plants, impacting restoration efforts. In a Cerrado grassland undergoing restoration study, we tested whether soil acidification could restore native soil conditions and control invasives using 56 plots across 14 blocks. We hypothesized that decreased soil pH and nutrient availability would reduce invasive biomass and enhance diversity. We show that acidification reduced invasive biomass by 71%, with acidification negatively affecting invasives while sparing natives. Maintaining nutrient‐poor soil conditions can help to control invasive grasses in restoration projects, as fertilizer application can favor invasive species establishment. Soil acidification effectiveness depends on local nutrient levels. Areas with high soil cation content may require larger amendment quantities. Restoration strategies in nutrient‐poor ecosystems should aim recovering historical soil conditions to control invasives growth and support slow‐growing native plants. [ABSTRACT FROM AUTHOR]

One of the goals of sustainable agricultural production is to avoid soil contamination by elements defined as trace metals (TMs). The aim of this study was to assess the long-term impact of the use of pig slurry (PS) and NPK mineral fertilizers on the soil content of cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn). In a 9-year crop rotation, PS was used three times only before root crops. The same four levels of NPK doses (N0P0K0, N1P1K1, N3P2K2, N4P2K2) were applied to both plots with and without PS. Soil samples were collected in early spring from topsoil (0–0.3 m) and subsoil (0.3–0.6 m). Three forms of TMs were determined in the soil: pseudo-total (Aqua regia); bioavailable (Mehlich 3 method) and readily bioavailable (mobile) forms (1 M NH4NO3). The tested factors did not have a significant impact on the Cd, Cu and Pb content, regardless of the form analyzed and the soil depth. PS application significantly increased the content of bioavailable forms of Zn regardless of the year, and the content of pseudo-total Zn only in the sugar beet year, i.e. after manure application. Increasing NPK doses increased the content of mobile Zn in the topsoil, especially in PS plots. A tendency to accumulate mobile forms of Cd and Pb was also observed on NPK-fertilized plots. Thus, long-term application of high NPK doses may increase the risk of contamination of the food chain with these metals. The content of mobile Cd and Zn was positively related to the content of total nitrogen in the soil and negatively related to pH. [ABSTRACT FROM AUTHOR]

Tobacco bacterial wilt is a major limiting factor for tobacco production and development, and it is more likely to occur under perennial single cropping of tobacco. In recent years, the rotation of tobacco-radish has gradually become popular. Therefore, we studied the effects of years of tobacco–radish rotation on tobacco bacterial wilt occurrence and rhizosphere microorganisms. The results indicated that both SY and TY could significantly reduce the risk of tobacco bacterial wilt occurrence, and SY had the lowest disease index. The rotation of radish plants significantly increased the soil pH but decreased the contents of alkali-hydrolysed nitrogen and organic matter in the soil. Alkali-hydrolysed nitrogen and pH are the key factors affecting the composition of the bacterial community. Furthermore, radish rotation changed the composition of the soil microbial community, increased the diversity of the bacterial community, and significantly altered the bacterial community structure. At the genus level, the abundance of Sphingomonas species negatively correlated with Ralstonia increased significantly, while the relative abundance of Rhodanobacter species positively correlated with Ralstonia decreased significantly. Disease index, pH and available phosphorus were the main factors affecting the variation in different bacterial genera. The network analysis results showed that Ralstonia was less connected in the network than in the CK group, and the SY treatment group had a more complex bacterial network structure. Overall, 2 years of tobacco and radish rotation improved the bacterial community structure of the rhizosphere soil and alleviated the harm caused by tobacco bacterial wilt, which is highly important for the stability and health of the rhizosphere soil ecosystem. [ABSTRACT FROM AUTHOR]

Background and aims: As a significant land carbon sink, highly acid subtropical forests in southern China continued to accumulate a significant amount of soil carbon under elevated acid deposition, yet the mechanism of how soil organic carbon (SOC) and its two components: particulate (POC) and mineral-associated (MAOC) organic carbon increased remain unclear. We aim to assess which mechanism and drivers dominated the accumulation of SOC and its two fractions under elevated acid deposition. Methods: We conducted a 11-year field acid addition experiment to study how acid deposition affected the accumulation of SOC and its fractions. Lignin phenols and amino sugars were used as two tracers for plant- and microbe-derived carbon. Results: We found that both POC (0–20 cm) and MAOC (10–20 cm) were significantly increased by acid addition. Acid addition significantly reduced the contributions of fungal-, bacterial- or total microbial residue carbon to SOC but significantly increased the plant-derived soil carbon in both soil depths. The increase of lignin phenol and suppressed soil organic matter decomposition from soil microbes suggested that soil POC increased with acid addition. Soil acidification strongly enhanced MAOC accumulation through increased lignin and mineral protection by iron-aluminum oxides and cations. Conclusion: Our results showed that increased mineral protection of plant-derived carbon was the dominant driver of the increased SOC sequestration under acid addition. This finding identified the dominant pathway for SOC accumulation in a highly acidic subtropical forest and provides new insights into understanding how plant-soil-mineral interact under increasing acid deposition in the region. [ABSTRACT FROM AUTHOR]

Background and aims: Nitrogen (N) deposition is a global driving factor that affects microbial biomass and ecosystem processes. However, it remains unclear whether N enrichment impacts microbial biomass in soil across ecosystems. Methods: In this study, we synthesized 125 studies worldwide to evaluate the effects of N addition on soil microbial biomass. Results: We found that N enrichment substantially suppresses total microbial biomass, including bacterial, fungal, and arbuscular mycorrhizal fungi biomass. Importantly, we found strong negative effects on microbial biomass globally caused by N-enrichment-induced soil acidification. Moreover, N enrichment mainly shapes the acidification of soil through the increased concentration of ammonium and by changing exchangeable cations in soil, including magnesium, calcium, sodium, manganese, and aluminum ions. Conclusions: Overall, our findings demonstrate that N-enrichment-induced soil acidification is a crucial factor to consider for preserving microbial communities and ecosystem function under future trends of increasing N enrichment. [ABSTRACT FROM AUTHOR]

With the acceleration of urbanization, while the amount of fertilizers used in agricultural production is increasing rapidly in industrial development, heavy metal pollution is also becoming more severe. Excessive use of fertilizers can lead to soil acidification, compaction, and degradation, while the sharp increase in heavy metal pollution observed also has adverse effects on soil quality and crop quality. Therefore, to prevent the loss of phosphorus from soil, improve the utilization rate of nitrogen in soil, and control cadmium pollution, the effects of biochar on the adsorption of nitrogen, phosphorus, and cadmium in soil were explored in this study. The following four experimental treatments were conducted: no biochar application, straw charcoal application, fruit shell charcoal application, and coconut shell charcoal application. Samples were collected from different soil depths (0 cm and 10 cm) after both 14 days and 28 days. The contents of total nitrogen, phosphorus, and cadmium were compared. The research findings indicate that these three types of biochar exhibit significant adsorption effects on nitrogen and phosphorus elements. Nevertheless, the adsorption effect on cadmium is not pronounced, potentially due to the stability of the biochar, the activity of microorganisms in the soil, and the alteration of cadmium speciation, which consequently results in an increase in cadmium content. [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]

Human decomposition in terrestrial ecosystems is a dynamic process creating localized hot spots of soil microbial activity. Longer-term (beyond a few months) impacts on decomposer microbial communities are poorly characterized and do not typically connect microbial communities to biogeochemistry, limiting our understanding of decomposer communities and their functions. We performed separate year-long human decomposition trials, one starting in spring, another in winter, integrating bacterial and fungal community structure and abundances with soil physicochemistry and biogeochemistry to identify key drivers of microbial community change. In both trials, soil acidification, elevated microbial respiration, and reduced soil oxygen concentrations occurred. Changes in soil oxygen concentrations were the primary driver of microbial succession and nitrogen transformation patterns, while fungal community diversity and abundance was related to soil pH. Relative abundance of facultative anaerobic taxa (Firmicutes and Saccharomycetes) increased during the period of reduced soil oxygen. The magnitude and timing of the decomposition responses were amplified during the spring trial relative to the winter, even when corrected for thermal inputs (accumulated degree days). Further, soil chemical parameters, microbial community structure, and fungal gene abundances remained altered at the end of 1 year, suggesting longer-term impacts on soil ecosystems beyond the initial pulse of decomposition products. [ABSTRACT FROM AUTHOR]

At present, the soil of Chinese greenhouses is experiencing severe nitrogen input in the form of fertilizer, which will cause damage to the soil environment and restrict crop growth in the long run. The response of potential functions of microorganisms as drivers of nutrient cycling and material transformation to nitrogen enrichment has rarely been reported in northern vegetable planting systems. Therefore, we set up four cucumber pot experiments with different nitrogen addition rates (0, 258, 516, and 1032 kg N ha−1 yr−1) in the greenhouse. Bacterial and fungal communities were detected by 16S and ITS rRNA gene sequencing, and bacterial and fungal functional groups were predicted using the FAPROTAX and FUNGuild databases. The findings showed that nitrogen addition induced soil acidification (a decrease of 0.25–1.63 units) significantly reduced microbial diversity and changed the community composition of bacteria and fungi. The relative abundance of bacterial functional groups associated with the nitrogen cycle increased significantly when medium and high levels of nitrogen were added. Conversely, the bacterial functional groups involved in the carbon cycle exhibited the opposite pattern. In this study, NO3− and soil pH were the main factors affecting the soil microbial community and its functional groups. Our results highlight that hydrocarbon degradation and saprophytic fungi may play key roles in yield formation during cucumber cultivation in northern solar greenhouses. In general, adopting a fertilization strategy that ensures low-medium nitrogen availability can contribute to the sustainable progress of facility agriculture. [ABSTRACT FROM AUTHOR]

Cropland acidification seriously restricts sustainable agricultural development. The main purpose of this study was to determine whether deeper tilling could alleviate topsoil acidification to improve the quality of arable land. A soil column incubation experiment simulating tillage depths (10 cm, 30 cm and 50 cm) and lime addition was conducted to determine their effects on soil acidification improvement. The changes in soil pH, exchangeable acidity, ammonium nitrogen (NH4+-N), nitrate nitrogen (NO3−-N), available phosphorus (AP), and microbial phospholipid fatty acids (PLFA) were analyzed. Tillage depth, lime application, and their interaction all had significant impacts on soil pH. T50 (simulated tillage depth of 50 cm) and T50+Lime (simulated tillage depth of 50 cm plus lime) treatments significantly increased the topsoil pH from 5.41 to 6.35 and 7.12, respectively. T50 treatment significantly reduced the soil exchangeable acid content compared to the T10 treatment. The nutrient accumulation along soil column indicated that the T50 and T50+Lime treatments significantly increased NO3−-N and AP content in the >30–50 cm soil layer. Compared with T30, NO3−-N accumulation in the >30–50 cm soil layers of T50 and T50+Lime treatments was 6.62 and 7.93 times higher, respectively. The accumulation of AP in the >30–50 cm soil layers of the T50 and T50+Lime treatments was 1.33 and 1.54 times higher than in the T30 treatment, respectively. These findings imply tillage up to 50 cm without exogenous materials could be a potential measure to reduce topsoil acidification and increase nutrition availability of >30–50 cm soil layers. Tillage of up to 30 cm combined with lime application confers greater benefits, which would particularly impact crops with shallow root systems. Subsequent field experiments will be conducted to further investigate the efficacy of these strategies in enhancing crop yield. [ABSTRACT FROM AUTHOR]

Abstract Background Conventional management (CM), substantial fertilization and flooding irrigation, has led to soil acidification, the decrease in soil bacterial diversity in bamboo forests. Integration of water and fertilizer management (IWF) can effectively improve the efficiency of water and fertilizer use, but its effect on soil environment, especially on microbial community, is still unclear. Methods Here, we used next-generation high-throughput sequencing to compare soil properties and bacterial communities through different fertilization and irrigation methods under IWF and CM. Results Compared to the control group, CM significantly reduced soil pH and bacterial diversity, while IWF improved soil nutrition status, increased soil bacterial diversity and soil pH to a level similar to the control group. Compared with CM, IWF also improved the relative abundance of beneficial bacteria and copiotrophic bacteria community in the soil, and the bacterial community in IWF was similar to CK. The structure of the bacterial community was also significantly correlated with soil organic matter, total nitrogen, hydrolyzable nitrogen, and available potassium, while soil bacterial diversity was mainly associated with soil hydrolyzable nitrogen. Conclusions IWF can play an important role in preventing soil acidification, the loss of soil bacterial diversity, and improving the structure of the bacterial community under specific conditions.

Abstract Fruit acidity significantly influences fruit flavor, but the specific impact of soil pH on fruit acidity remains unclear. This study investigated the effects of various soil pH levels on fruit acidity and citric acid (CA) metabolism in lemon (Citrus limon L.). High soil pH (pH 8) decreased total soluble solids concentrations in lemon fruits, while low soil pH (pH 4) increased titratable acid and CA concentrations. Although low soil pH reduced the synthesis of CA due to the decreased citrate synthase and phosphoenolpyruvate carboxylase activities, the elevated fruit acidity under low soil pH conditions is not directly related to CA synthesis. Instead, low soil pH was found to suppress the activity of cytosolic aconitase (Cyt-ACO), an iron-dependent enzyme, indicating a potential role for CA degradation inhibition in low soil pH-induced CA accumulation. Furthermore, low soil pH significantly reduced cytosolic iron (Cyt-Fe) concentration, which was positively correlated with Cyt-ACO activity. In conclusion, low soil pH contributes to increasing fruit acidity in lemon, partially by inhibiting CA degradation due to the reduced Cyt-Fe concentrations. Our work unravels the influence of soil pH on CA accumulation and provides important clues for modulating CA levels through microelement fertilization in citrus.

Background and aims: Planting medicinal herbs under forests is popular as a new cultivation mode for producing high quality herbal medicine. However, soil acidification under forests could aggravate soil-borne diseases, posing a major threat to production. The objective of the study was to investigate strategies for mitigating soil acidification and elucidate its underlying mechanism. Methods: We used Panax notoginseng planted under forests with different acidified soil backgrounds to test the effects of exogenous soil amendments on soil chemical properties and rhizosphere microbial communities and then decipher their relationship with root rot disease in P. notoginseng. Results: The results indicated that the appropriate dosage of soil amendments with lime, calcium magnesium phosphate, and organic manure individually and their mixture could alleviate root rot disease and promote the growth of P. notoginseng by increasing pH and modifying other soil chemical properties. The abundance and diversity of rhizobacteria increased with increasing soil pH, especially beneficial rhizobacteria including Bradyrhizobium, Rhodoplanes, Mesorhizobium and Gemmatimonas, which modified the soil microbial community by enriching beneficial bacteria and suppressing pathogens to alleviate root rot disease. However, high EC and AN caused by over-dose amendments had the negative impacts on soil microbial communities, resulting in root rot disease exacerbation. Conclusion: Alleviating soil acidification to a suitable level could suppress root rot disease by modifying soil chemical properties and enriching beneficial soil rhizobacteria. The findings would be an effective practice toward ameliorating acidic soil under forests to reduce soil-borne disease. [ABSTRACT FROM AUTHOR]

The rapid increase in nitrogen (N) and phosphorus (P) availabilities in terrestrial ecosystems has led to sustained shifts in soil microbial communities and microbially‐mediated N‐cycling. However, the specific effects of N and P amendments on N‐cycling microbes are poorly understood. This meta‐analysis synthesizes the effects of N and/or P amendments on the abundances and functional potentials of N‐cycling genes involved in N₂ fixation, organic N mineralization, nitrification, and denitrification across natural ecosystems and diverse soil conditions in China. Our findings indicate that ammonia‐oxidizing bacteria (AOB) showed greater responsiveness to N amendment than ammonia‐oxidizing archaea (AOA), and AOB amoA abundance increased while AOA amoA abundance decreased with P amendments. Additionally, the abundance of nirS declined, while nirK abundance remained unresponsive to both N and P amendments. These findings highlight the distinct ecological niches occupied by microbial groups with equivalent functions in response to N and P amendments. Moreover, our findings indicate that soil N and P availabilities, along with soil acidification induced by N additions and microbial biomass carbon content, are key factors regulating N‐cycling gene abundances and potentials. The driving mechanisms for N‐cycling genes and their corresponding potentials appear to be distinct, with gene abundance showing only a limited influence on functional potentials. This suggests that factors such as soil properties and microbial community compositions may be more critical determinants of N‐cycling processes than functional gene abundances with regard to scenarios of increasing N and P deposition. [ABSTRACT FROM AUTHOR]

Background and Aims: Over the last few decades, rampant nitrogen fertilization has exacerbated soil acidification in agricultural ecosystems. To counteract this, liming has become an essential technique for rehabilitating fertility in acid-degraded agricultural soils. Our research aimed to shed light on the response of ammonia oxidizers to liming in acidic soils within a controlled rice paddy experiment. We conducted a pot experiment with rice, featuring three different treatments: a control with only soil, a low dolomite dose (LD), and a high dolomite dose (HD). Various soil properties were investigated throughout the study. Under flooding, soil pH values rose across the treatments, from 5.4 in the control to 6.8 in HD. Ammonium and nitrate levels peaked in the HD treatment, reaching 30 and 22 mg kg−1, respectively. Similarly, dissolved organic carbon and microbial biomass carbon surged at mid-season aeration, hitting highs of 101 and 30 mg kg−1, respectively, in the HD treatment. Ammonia-oxidizing bacteria (AOB) and archaea (AOA) were responsive to dolomite-lime application, with distinct reactions; AOB abundance and potential nitrification rates were positively affected by higher lime doses, whereas AOA numbers decreased over time and with dolomite application. Additionally, soil enzymes such as urease, catalase, invertase, phenol oxidase, and phosphatase also increased progressively, mirroring the rise in soil pH. This study identified increased soil pH as the critical factor influencing various soil parameters, especially the balance between AOA and AOB populations. Both AOB and AOA were sensitive to liming; AOA decreased while liming stimulated AOB abundance. [ABSTRACT FROM AUTHOR]

Codonopsis pilosula is an important medicinal plant in China. Continuous cropping of C. pilosula affects crop quality and yield. However, comprehensive research on the impacts of continuous cropping on soil properties, microbial community structures, and soil metabolites is lacking. This study involved collecting rhizosphere soil samples from C. pilosula monocropped for 1 to 4 years to analyze variations in soil properties, microbial community structure, and metabolites across different continuous-cropping years (CCYs) through metabolomic and microbiomic analyses. Significant variations in the soil properties were observed; total phosphorus (TP) and available potassium (AK) in the rhizosphere soil increased with the number of CCYs, and pH declined. The microbial community structure significantly changed with continuous cropping. Overall, the soil bacterial diversity decreased with increasing CCY. The abundances of Proteobacteria and Firmicutes significantly decreased with increasing CCY, whereas the abundance of Acidobacteria significantly increased. The fungal diversity tended to decrease, with an increase in the abundance of beneficial Basidiomycota and an increase in potentially pathogenic Rozellomycota. Metabolomic analysis revealed 101 metabolites and significant changes in lipid compounds, organic acids, phenols, and carbohydrates. Notably, autotoxic substances such as 2,6-di-tert-butylphenol accumulated with increasing CCY. The results indicated that the main factors causing continuous-cropping obstacles in C. pilosula were soil nutrient imbalance and autotoxic substance accumulation. Continuous cropping of C. pilosula significantly altered the microbial community structure and metabolomic profile of rhizosphere soils. Effective management practices are needed to mitigate soil acidification, nutrient imbalances, and autotoxic substance accumulation during continuous cropping. Future research should focus on integrated soil management strategies to maintain soil health and crop productivity in C. pilosula continuous-cropping systems. [ABSTRACT FROM AUTHOR]

Atmospheric nitrogen (N) deposition has notably increased since the industrial revolution, doubling N inputs to terrestrial ecosystems. This could mitigate N limitations in forests, potentially enhancing productivity and carbon sequestration. However, excessive N can lead to forest N saturation, causing issues like soil acidification, nutrient imbalances, biodiversity loss, increased tree mortality and a potential net greenhouse gas emission. Traditional experiments often overlook the canopy's role in N fate, focusing instead on direct N addition to the forest floor. In our study, we applied 20 kg N ha y−1 of labeled 15NH415NO3 solution (δ15N = 30‰) both above and below the canopy, maintaining also control plots. We assessed ecosystem components before and after treatment, calculated N stocks, and used mass balance for fertilizer recovery analysis. Findings revealed that the above-canopy N addition intercepted up to 31 ± 4% of added N in foliage, a significant contrast to the negligible recovery in leaves with below-canopy treatment. Overall plant recovery was higher in the above-canopy treatment (43 ± 11%) compared with below (9 ± 24%). Post-vegetative season, about 15 ± 1% of above-canopy added N was transferred to soil via litterfall, indicating substantial N reabsorption or loss through volatilization, stemflow or throughfall. In contrast, the below-canopy approach resulted in just 4.0 ± 0.6% recovery via litterfall. These results highlight a significant difference in N fate based on the application method. Nitrogen applied to the canopy showed distinct recovery in transient compartments like foliage. However, over a few months, there was no noticeable change in N recovery in long-lived tissues across treatments. This implies that N application strategy does not significantly alter the distribution of simulated wet N deposition in high Carbon/N tissues, underscoring the complex dynamics of forest N cycling. [ABSTRACT FROM AUTHOR]

Summary: The primary mechanisms contributing to nitrogen (N) addition induced grassland biodiversity loss, namely light competition and soil cation toxicity, are often examined separately in various studies. However, their relative significance in governing biodiversity loss along N addition gradient remains unclear.We conducted a 4‐yr field experiment with five N addition rates (0, 2, 10, 20, and 50 g N m−2 yr−1) and performed a meta‐analysis using global data from 239 observations in N‐fertilized grassland ecosystems.Results from our field experiment and meta‐analysis indicate that both light competition and soil cation (e.g. Mn2+ and Al3+) toxicity contribute to plant diversity loss under N enrichment. The relative importance of these mechanisms varied with N enrichment intensity. Light competition played a more significant role in influencing species richness under low N addition (≤ 10 g m−2 yr−1), while cation toxicity became increasingly dominant in reducing biodiversity under high N addition (>10 g m−2 yr−1). Therefore, a transition from light competition to cation toxicity occurs with increasing N availability.These findings imply that the biodiversity loss along the N gradient is regulated by distinct mechanisms, necessitating the adoption of differential management strategies to mitigate diversity loss under varying intensities of N enrichment. [ABSTRACT FROM AUTHOR]

The proportion of European ash (Fraxinus excelsior L.) stands decreased rapidly over the last thirty years. The highest declines are recorded in fertile ash-dominated habitats. Thus, a comprehensive understanding of successful ash establishment is needed across broader habitat conditions. Therefore, we aimed to investigate ash natural regeneration in pine-ash forests and adjacent pine-dominated forests without ash in overstory but with ash regeneration. We assessed the effects of soil environment, soil moisture, browsing, ash regeneration density and its health status. The most limiting factors of ash regeneration were low soil moisture, high soil acidity, and the increase of pine proportion. We noted the highest densities only for ash regeneration of up to 0.6 m height growing on moderately acidic soils in pine-ash forests. Our models showed a low number of saplings damaged by ash disease. Instead, we revealed a high proportion of drought-damaged saplings without dieback symptoms. The highest browsing occurred within pine-ash forests with a lower proportion of pine trees in overstory. Despite theoretically unfavourable soil conditions, we state that pine-ash forests can harbour ash regeneration and may allow for its natural and assisted recolonization. In contrast, within pine-dominated forests located in the vicinity of pine-ash stands, the successful regeneration of ash is negligible due to high soil acidification and low moisture. [ABSTRACT FROM AUTHOR]

The study explored the performance of hybrid and population rye (Secale cereale) cultivars under two different crop management intensities in Poland: moderateintensity and high-intensity management. The focus was grain yield, grain quality, yield components, and variety stability in two growing seasons (2018/2019 and 2019/2020) at three locations. Hybrid cultivars consistently yielded higher grain yields (9.81 t ha−1) than population cultivars (7.90 t ha−1), with increase of 24.9%. However, hybrid cultivars had lower protein content (8.94%) than population cultivars (9.77%). Spike number was the most influential factor on yield, followed by 1000-grain weight and grains per spike, regardless of cultivar type. Hybrid cultivars displayed a lower degree of stability as assessed using the ranking sum of the Shukla variance and the multi-trait stability index. Hybrid cultivars were strongly dependent on resistance to fungal diseases, including Septoria (Mycosphaerella graminicola), and increased stability under moderate-intensity management. Resistance to soil acidification became more important for cultivar stability under high-intensity management [ABSTRACT FROM AUTHOR]

Phosphorus (P) is one of the essential elements for plant growth and is a key factor in maintaining the productivity of subtropical forest ecosystems. Chinese fir (Cunninghamia lanceolata) is mainly distributed in subtropical areas of China, and its soil acidification and phosphorus utilization efficiency are low. It is of great significance to study the effects of Chinese fir plantation transformation on soil P for the stability of ecosystem and sustainable forest management. In this study, the rhizosphere and non-rhizosphere soils were collected from the replanted Chinese fir plantation, Castanopsis hystrix plantation, Mytilaria laosensis plantation and the mixed plantation of Castanopsis hystrix and Mytilaria laosensis on the cutting-blank of Chinese fir plantation in South Asia, and the effects of soil P component and transformation on the transformation of Chinese fir plantation into broad-leaved forest were studied. The results were as follows: (1) The content of microbial biomass phosphorus and the activity of acid phosphatase in rhizosphere and non- rhizosphere soil of the modified Castanopsis hystrix plantation, Mytilaria laosensis plantation and the mixed plantation of Castanopsis hystrix and Mytilaria laosensis were significantly higher than those of Chinese fir plantation. The contents soil total phosphorus of Castanopsis hystrix plantation and the mixed plantation of C. hystrix and Mytilaria laosensis were more easily converted to quick available phosphorus than those of Chinese fir plantation and M. laosensis plantation. (2) The contents of calcium chloride extraction phosphorus in rhizosphere and non-rhizosphere soils of Castanopsis hystrix plantation and the mixed plantation of C. hystrix and Mytilaria laosensis were significantly higher than those of Chinese fir plantation and M. laosensis plantation, and the contents of enzyme extraction phosphorus, hydrochloric acid extraction phosphorus and citric acid extraction phosphorus in rhizosphere and non-rhizosphere soils of M. laosensis plantation and Castanopsis hystrix/Mytilaria laosensis mixed plantation were significantly higher than those of Chinese fir plantation and Castanopsis hystrix plantation. (3) RDA results showed that soil water content and microbial biomass carbon were the key factors regulating P components in rhizosphere and non-rhizosphere soils, respectively. In summary, the transformation of Chinese fir plantation into broad-leaved forest is conducive to the storage and supply of forest soil P, and this study provides an important scientific reference for tree species selection and management strategies to improve soil P availability in south subtropical plantations. [ABSTRACT FROM AUTHOR]

In order to achieve sustainable development of the tea industry in China, it is necessary to reduce the use of chemical fertiliser rationally. With conventional fertilisation (CF) treatment as the control, five different chemical fertiliser-reduced regimes, including tea-specific formula fertiliser (T1), T1 + acidification amendment (T2), organic substitution based on T1 (T3), urea formaldehyde slow-release fertiliser (T4) and carbon-based organic fertiliser (T5), were conducted and evaluated on a green tea plantation from 2018 to 2021. The results showed that the spring tea yield of T1–T5 increased by 4.65–28.67%, while the free amino acids, tea polyphenols and sensory evaluation scores did not remarkably decrease. In addition, the T1–T5 treatments had a slight effect on soil acidification mitigation (except T2) and maintained the essential nutrients for tea production. Nutrient use efficiency improved, with agronomic efficiency (AE) increasing by 0.01–0.08 kg kg−1, shoot nutrient use efficiency (NUE) by 0.14–0.70% and partial factor productivity (PFP) by 0.05–0.18 kg kg−1. The net economic benefits also improved, with T1 showing a 135.28% increase, followed by T3 (67.53%), T2 (48.65%), T4 (38.07%) and T5 (33.35%). Overall, our results indicated that the T1 treatment could maintain the tea yield and quality while reducing the chemical fertiliser input and maximising the net economic benefit and AE. [ABSTRACT FROM AUTHOR]

The application of urea as a nitrogen fertilizer and herbicide is a common practice in agricultural systems. However, there is no background information on how the soil acidification caused by urea might affect the herbicide bioavailability in volcanic soils. The persistence study was conducted under microcosm incubation conditions in two Andisol soils amended with a field equivalent nitrogen dose of 200 kg N ha−1 and double dose of 400 kg N ha−1. Clopyralid, fluroxypyr, picloram, and triclopyr, acidic ionizable herbicides, were applied at the field equivalent dose. Adsorption studies were also carried out on both soils at pH 4, 5, and 6. Clopyralid and picloram showed the greatest increase in half-life in the range of 20–80%. The application of twice the dose of urea resulted in minor changes. A higher adsorption implies a higher persistence of the herbicides. This was more evident for the Piedras Negras soil (PNS). The conclusion of this work is that soil acidification by urea increases the persistence of ionizable herbicides in Andisol soils and that this effect depends on the acidity of the herbicide and the physico-chemical characteristics of the soil, which are among the most determining factors. [ABSTRACT FROM AUTHOR]

Background and aims: Crop rotation can effectively alleviate the obstacles of continuous cropping and restore the agroecological balance, and then determining the optimal length of crop rotation is the cornerstone of effective crop rotation. To delve into this issue, we conducted a six-year rotation experiment aimed at exploring how different rotation lengths impact sugar beet yield, soil properties, and microbial communities. Methods: Conduct field experiments to gather rhizosphere soil samples from treatments with different rotation lengths of sugar beet and analyze their physicochemical properties and microbial characteristics. Subsequently, establish a model linking sugar yield with the physicochemical properties and microbial characteristics of the rhizosphere soil. Results: Sugar beet, sugar content, and sugar yield significantly increased while decreasing disease symptoms, with increases in crop rotation length. Longer rotations significantly ameliorated soil acidification and improved soil fertility. On the other hand, extending the crop rotation length significantly altered the community structure of microbial sub-communities with varying abundances. Additionally, the fungal diversity increased and ecological network became more complex, and a multitude of potentially beneficial microbiota were enriched in the rhizosphere soil with rotation length. Conclusion: These results demonstrate that extending the crop rotation length improved soil conditions, and increased sugar beet yield. In addition, we recommend that sugar beet rotation length should be at least three years or more. [ABSTRACT FROM AUTHOR]

Background: Anthropogenic ammonia emissions, primarily derived from agriculture, lead to air pollution, soil acidification, and surface water eutrophication, all of which adversely affect human health and ecosystems. Slurry treatment technologies in the form of additives represent an underutilized means of reducing gaseous emissions. Information regarding the potential of additives to reduce ammonia in soil surface‐applied slurries is scarce. Aim: This study aims to develop a 15N mass balance technique to quantitatively measure ammonia losses from different slurries containing multiple additives that are applied to outdoor soil‐filled containers. Methods: The experiments were performed under free‐air conditions. Isotopically labeled slurries from biogas, cattle, and pigs containing 18 additives were surface‐applied to soil‐filled containers and exposed for 72 or 48 h. The additives included inorganic and organic adsorbents, five amounts of sulfuric acids, molasses ± effective microorganisms, and water dilution. After termination of the ammonia loss period, a suite of soil preparation steps for the quantitative recovery of the labeled ammonium remaining in the soil was developed, and subsequently the loss of NH4‐N was determined. Results: In the control treatments, ammonia losses from biogas, cattle slurries, and pig slurries averaged 54.4%, 33.9%, and 11.0%, respectively. The adsorbents did not decrease or only slightly decreased ammonia emissions. Ammonia abatement by sulfuric acid was nearly complete at pH values of 5.9 and 5.8 for the biogas and pig slurry, respectively, and about 80% at pH 5.2 for the cattle slurry. In comparison, more moderately decreased pH values with sulfuric acid showed a similar reduction as molasses and a 1:1 dilution for the three slurries. Adding microorganisms to the molasses did not further decrease ammonia losses. Conclusion: The newly developed 15N mass balance technique, which allows a precise estimate of ammonia losses, can serve as a reference method to assess ammonia losses from field‐applied slurries containing various additives and as a standard comparison technique for other ammonia measurement techniques. [ABSTRACT FROM AUTHOR]

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Purpose: The Buenavista del Cobre mine is in a semiarid environment in NW Mexico. A part of the mine tailings dam has been flooded with wastewater from Cananea, generating an artificial wetland. The main objectives of this work were to evaluate the effect of wastewater on the pedogenesis of wetland Technosols developed on mine tailings and to compare them with the soil of non-irrigated tailings and with a natural soil profile. Materials and methods: Three profiles were studied inside the dam as follows: a profile under waterlogging conditions, a profile under conditions of periodic sewage saturation, and a profile with no waterlogging conditions. Laboratory methods included the micromorphological analysis of the soil structure and pedo-features, fertility properties, identification of clay minerals, and analysis of bulk chemical composition. Results and discussion: It was found that the biogenic structure and voids associated with organic materials were the main micromorphological features of the studied wetland Technosols. Primary sulfides remained unaltered in the Technosols irrigated with wastewater, whereas incipient sulfide oxidation was observed in the non-irrigated tailings. Chlorite and smectite were detected in the Technosols. Such mineral assemblage was found to be mostly generated by hydrothermal processes. Conclusion: Irrigation of tailings with wastewater supported the biological aggregation and porosity formation within the soil matrix, supplied plant nutrients, and enhanced the ecological soil quality of the studied hydromorphic Technosols. Saturation with wastewater hampered the oxidation of primary sulfides in the hydromorphic Technosols, preventing soil acidification and the mobilization of heavy metal contaminants. [ABSTRACT FROM AUTHOR]

The rapid increase in reactive nitrogen (N) released into the environment by human activities has notably altered the structure and composition of forest soil microbial communities (SMCs), profoundly impacting the N cycle in terrestrial ecosystems. However, the response of soil microorganisms to nitrogen addition in different seasons is not clear. This study delved into how SMCs in a subtropical region of central Yunnan, China, specifically in an evergreen broad-leaved forest (EBLF), respond to N deposition during both the dry and wet seasons. Through high-throughput sequencing, we assessed the composition and structure of SMCs under varying N addition treatments across seasons, examining their interplay with soil chemical properties, enzyme activities, and community responses. The findings revealed significant outcomes following four years of N addition in the subtropical EBLF: (1) Significant changes were observed due to the interaction between N addition and seasonal changes. Soil pH significantly decreased, indicating increased soil acidification, particularly in the dry season. Increased moisture in the wet season mitigated soil acidification. (2) In the dry season, N addition led to a decrease in microbial richness and diversity. In the wet season, N addition increased microbial richness and diversity, alleviating the downward trend observed in the dry season. (3) N addition significantly impacted the composition of soil bacterial and fungal communities. Dominant fungal genera in the wet season were particularly sensitive to N addition. (4) Seasonal changes and N addition altered soil microbial community structures. Soil chemical properties and enzyme activities significantly influenced the microbial community structure. However, due to differences in soil moisture, the key environmental factors that regulate microbial communities have changed significantly during the dry and wet seasons. This study serves as a foundation for understanding how N deposition impacts SMCs in EBLF ecosystems in subtropical regions, offering valuable insights for the scientific management of forest ecological resources amidst global change trends. [ABSTRACT FROM AUTHOR]

Soil acidification is a global environmental problem with significant impacts on agricultural production, environmental protection, and ecosystem health. Soil acidification is widespread in China, affecting crop yields, agricultural product quality, and biodiversity. Since the 1980s, much work has been done on acidic soils in China, but it is controversial whether excessive nitrogen fertilizer application can lead to soil acidification mechanisms. To address the above issues, we conducted a meta-analysis of 115 published papers to integrate and analyze the effects of N fertilizer application on soil acidification and biological properties from 1980 to 2024. We also quantified the effect of nitrogen fertilization on soil acidification and biological changes under different climatic conditions. The results showed that under long-term application of nitrogen fertilizers in China from 1980 to 2024, soil pH decreased by an average of 15.27%, and the activities of soil urease, nitrate reductase, nitrite reductase, catalase, glutamate dehydrogenase, and glutamate synthetase decreased by an average of 9.82–22.37%. The soil microbial community richness (Chao1 index) increased by 6.53%, but the community diversity (Shannon index) decreased by 15.42%. Among the dominant soil microorganisms, the relative abundance of bacteria decreased by an average of 9.67–29.38% and the abundance of gene expression of nifH, amoA-AOA, amoA-AOB, and qnorB decreased by 9.92–19.83%. In addition, we found that the mean annual temperature and rainfall impacted soil acidification via their effect on soil microbial diversity and community composition. This study provides a scientific basis for an in-depth understanding of the spatial and temporal variation of soil acidification and biological properties in China. [ABSTRACT FROM AUTHOR]

Climate change and soil acidification are critical factors affecting crop production and soil quality. This study comprehensively analyzed the impact of fertilization practices, including conventional (CA), sustainable (SA), and unfertilized (BK), on soil properties, enzyme activities, and gene diversity in paddy fields across seasonal changes. Soil pH was significantly influenced by fertilization, with higher pH in BK and a decrease in pH with increased fertilization. Soil enzyme activities and Biolog EcoPlate™ analysis revealed the lowest activities in September, with the highest in December under different practices. Metagenomic analysis showed the highest genetic richness in CA soil, with seasonal variations influencing genetic diversity. From the perspective of genes in species taxonomy, Sorangium cellulosum and Anaeromyxobacter sp. were the most abundant taxa. Soil genes annotated by CAZy, COG, and GO databases revealed highly similar gene structures among different practices. Moreover, the genetic origins of soil enzymes were linked to specific bacterial contributors. While not all gene's diversity and abundance were associated with soil enzyme activity, arylsulfatase showed an obvious correlation. Enzyme activities proved more sensitive indicators of microbial activity than gene abundance. This study emphasizes the need for rational fertilization strategies to maintain soil enzyme activities, considering agricultural practices and seasonal variations. [ABSTRACT FROM AUTHOR]

Background: Forest soils are usually highly weathered and abundant in mineral-weathering bacteria, which have not been used to mobilize soil minerals for crop production. Here, we used an acidic forest soil with low available phosphorus (P), potassium (K), and silicon (Si) to isolate bacteria capable of co-solubilizing P, K, and Si (PKSi-solubilizing) and the model rice plant to test their potential to mobilize soil P, K, and Si for crop nutrition. Results: Six PKSi-solubilizing strains representative of common mineral-weathering proteobacteria taxa (genera Burkholderia, Paraburkholderia, Collimonas, Pseudomonas, and Agrobacterium) were screened out. They showed diverse P-, K-, or Si-solubilizing activities and produced diverse organic acids. Their mineral-solubilizing activities were positively correlated with the levels of medium pH reduction and gluconic acid production. They promoted the growth of rice seedlings grown in the forest soil by increasing soil available P and Si, plant P, K, and Si cumulative contents and dry weight, and the corresponding root-to-shoot ratios. The growth of rice seedlings alone and with the inoculated PKSi-solubilizing stains in the acidic forest soil did not reduce the soil pH. Conclusions: The forest soil with low available P, K, and Si is a valuable resource for high-performance PKSi-solubilizing bacteria improving soil fertility and crop nutrition. The PKSi-solubilizing bacteria screened out can promote rice seedling growth by mobilizing P, K, and Si from soil to plant in the acidic soil with low available P, K, and Si. They show potentials to mitigate soil P, K, and Si deficiency and promote crop growth, and to recover soluble P, K, and Si from chemical fertilizers and improve the use efficiency of chemical fertilizers, thus reducing the input of chemical fertilizers. They may retard soil acidification by Si-solubilization and improve soil quality. Highlights: Forest soils with low available P, K, and Si are resources of PKSi-solubilizing bacteria. PKSi-solubilizing bacteria at high abundance in soils are representative of common mineral-solubilizing taxa. PKSi-solubilizing bacteria promote crop growth via mineral-mobilization from soils to plants. PKSi-solubilizing bacteria produce organic acids to solubilize P, K, and Si. Si-solubilization may neutralize soil acidification. [ABSTRACT FROM AUTHOR]

The phenomenon of nitrogen deposition resulting in species loss in terrestrial ecosystems has been demonstrated in several experiments. Nitrogen (N) and phosphorus (P), as major nutrients required for plant growth, exhibit ecological stoichiometric coupling in many ecosystems. The increased availability of nitrogen can exacerbate the ecological effects of phosphorus. To reveal the ecological effects of phosphorus under nitrogen-limiting and non-limiting conditions, we conducted a controlled N-P interaction experiment over 5 years in the Hulunbuir meadow steppe, where two nitrogen addition levels were implemented: 0 g N·m-2·a-1 (nitrogen-limiting condition) and 10 g N·m-2·a-1 (nitrogen-non-limiting condition), together with six levels of phosphorus addition (0, 2, 4, 6, 8, and 10 g P·m-2·a-1). The results showed that nitrogen addition (under nitrogen-non-limiting conditions) significantly decreased species diversity in the steppe community, which was exacerbated under phosphorus addition. Under nitrogen-limiting conditions, phosphorus addition had no marked impact on species diversity compared to the control; however, there were substantial differences between different levels of phosphorus addition, exhibiting a unimodal change. Under both experimental nitrogen conditions, the addition of 6 g P·m-2·a-1 was the threshold for affecting the community species diversity. Nitrogen addition reduced the relative biomass of legumes, bunch grasses, and forbs, but substantially increased the relative biomass of rhizomatous grasses. In contrast, phosphorus addition only markedly affected the relative biomass of forbs and rhizomatous grasses, with the former showing a unimodal pattern of first increasing and then decreasing with increasing phosphorus addition level, and the latter exhibiting the opposite pattern. The different responses of rhizomatous grasses and other functional groups to nitrogen and phosphorus addition were observed to have a regulatory effect on the changes in grassland community structure. Phosphorus addition may increase the risk of nitrogen deposition-induced species loss. Both nitrogen and phosphorus addition lead to soil acidification and an increase in the dominance of the already-dominant species, and the consequent species loss in the forb functional group represents the main mechanism for the reduction in community species diversity. [ABSTRACT FROM AUTHOR]

Background Aims Methods Results Conclusion Neither the magnitude of boron (B) depletion in agricultural soils nor the driving factors of this process have been systematically studied before.The objectives of our study were to survey the extractable B (Be) in pristine soils as compared with cultivated soils, to estimate the yearly B depletion rate in agroecosystems, and to identify the edaphic, productive, and/or climatic factors determining that rate.Surface soil samples (0–20 cm layer) were taken from uncropped (UC) sites and nearby agricultural fields in 2011 and 2018 (AGR2011 and AGR2018, respectively) from the Argentinean Pampas. In these samples, Be and other edaphoclimatic and productive variables were determined, such as clay content, precipitation (PP), pH, evapotranspiration (ET), soil organic matter (SOM), and B removal with crop grains (RB).The Be concentration decreased with agricultural activity, because UC soils had an average Be value of 1.9 mg kg−1, whereas AGR2011 and AGR2018 soils had values of 1.3 and 0.9 mg kg−1, respectively. The depletion rate from 2018 to 2011 ranged from 0.01 to 0.06 mg kg−1 y−1, and the main factors associated with this process were RB, PP, soil acidification, and SOM depletion (promoting B depletion) and ET and clay (reducing depletion).At current rates, B depletion from these agricultural soils could compromise B availability for crops in the short‐to‐medium term, depending on regional differences caused by edaphoclimatic and productive differences (RB, PP, pH, SOM, ET, and clay). Urgent actions are required to halt and/or revert this soil degradation process. [ABSTRACT FROM AUTHOR]

The accumulation of excessive H+ can cause soil acidification and then affect the aggregation and dispersion of soil particles through changes in pH as well as electrolyte type and concentration. In this study, dynamic light scattering (DLS) technology was employed to investigate the aggregation kinetics of soil particles in several base cation solutions at different pHs. The results showed that, (1) specific ion effects of base cations were observed in aggregation rates, critical coagulation concentrations (CCCs) and activation energies for soil particle aggregation at different pHs; (2) H+ enhanced the aggregation rate, but reduced the CCC values and activation energies of the base cations, and then greatly promoted soil particle aggregation; (3) H+ strongly decreased specific ion effects of base cations on the aggregation rates, CCCs and activation energies for soil particle aggregation. The analyses of those differences related to soil aggregation kinetics in different base cation solutions at different pHs revealed that, the lower the pH, the weaker the electric field strength, and therefore the weaker the polarization of base cations and surface O‐atoms would be. Moreover, H+ reduced the charge density for soil particle aggregation, which was the main source for decreasing the electrostatic repulsive energy for soil particle aggregation at different pHs. The study improves our understanding of soil acidification effects on soil particle aggregation and aggregate stability. [ABSTRACT FROM AUTHOR]

SUMMARY: Poor management and excess fertilization of apple (Malus domestica Borkh.) orchards are causing increasingly serious soil acidification, resulting in Al toxicity and direct poisoning of roots. Strigolactones (SLs) are reported to be involved in plant responses to abiotic stress, but their role and mechanism under AlCl3 stress remain unknown. Here, we found that applying 1 μm GR24 (an SL analoge) significantly alleviated AlCl3 stress of M26 apple rootstock, mainly by blocking the movement of Al through cell wall and by vacuolar compartmentalization of Al. RNA‐seq analysis identified the core transcription factor gene MdWRKY53, and overexpressing MdWRKY53 enhanced AlCl3 tolerance in transgenic apple plants through the same mechanism as GR24. Subsequently, we identified MdPMEI45 (encoding pectin methylesterase inhibitor) and MdALS3 (encoding an Al transporter) as downstream target genes of MdWRKY53 using chromatin immunoprecipitation followed by sequencing (ChIP‐seq). GR24 enhanced the interaction between MdWRKY53 and the transcription factor MdTCP15, further increasing the binding of MdWRKY53 to the MdPMEI45 promoter and inducing MdPMEI45 expression to prevent Al from crossing cell wall. MdWRKY53 also bound to the promoter of MdALS3 and enhanced its transcription to compartmentalize Al in vacuoles under AlCl3 stress. We therefore identified two modules involved in alleviating AlCl3 stress in woody plant apple: the SL‐WRKY+TCP‐PMEI module required for excluding external Al by blocking the entry of Al3+ into cells and the SL‐WRKY‐ALS module allowing internal detoxification of Al through vacuolar compartmentalization. These findings lay a foundation for the practical application of SLs in agriculture. Significance Statement: We identified two modules involved in alleviating AlCl3 stress in woody plant apple: the SL‐WRKY+TCP‐PMEI module required for excluding external Al by blocking the entry of Al3+ into cells and the SL‐WRKY‐ALS module allowing internal detoxification of Al through vacuolar compartmentalization. [ABSTRACT FROM AUTHOR]

Coal mining causes surface subsidence, resulting in the loss of phosphorus from the soil surface and affecting crop growth. To provide a basis for the reclamation of soils in coal mining subsidence areas, using the Suntuan mine area in Huaibei City as an example, indoor soil cultivation experiments were conducted to investigate the effects of applying different types of phosphate rock powders (mechanically activated and nonmechanically activated), active minerals (zeolite, kaolin, bentonite) and phosphorus solubilizing microorganisms (Pseudomonas fluorescens, Aspergillus niger) on soil pH, available phosphorous content, and the conversion of soil phosphorus fractions. The results showed that the combined action of phosphate rock powder and phosphorus solubilizing bacteria could significantly improve the soil acidic environment. The application of phosphate rock powder, active minerals, and phosphorus solubilizing microorganisms can promote the release of available phosphorous in soil, and Aspergillus niger has a better effect than Pseudomonas fluorescens. Soil content of H2O-P, NaOH-Pi, NaHCO3-Pi, and HCl-P increased, NaOH-Po decreased, and some treatment groups had reduced Residual-P content. Together, phosphate rock powders, active minerals, and phosphorus solubilizing microorganisms can mitigate soil acidification, promote soil phosphorus release, result in the transformation of soil phosphorus fractions, and improve phosphate fertilizer utilization. [ABSTRACT FROM AUTHOR]

The article presents a study which investigated how urea use over an extended period affects the qualities of the soil. The researchers showed that yearly applications of urea over an extended time caused soil acidification and reduced the amount of exchangeable bases in the soil. Factors that have an impact on the crop yield are mentioned. Also noted are farmers' perception on the impact of chemical fertilizer on environment.

Soil acidification has emerged as a critical limiting factor for the sustainable development of the tea industry. In this article, a comprehensive review of 63 original research articles focusing on the impact of amendments on the pH in tea plantations soil was conducted. Through meta-analysis, the effect of applying soil amendments to increase the pH of tea plantation soil and its influencing factors were investigated. The results revealed that lime had a significant impact, increasing the pH by 18% in tea plantation soil, while rapeseed cake had a minimal (2%) effect. It was observed that as the quantity of amendments and pH levels increased, so did their impact on the pH of tea plantation soil. Subgroup analysis within biochar showed varying effects, depending on soil pH, with an 11% increase in acidic soil. Among these amendments, biochar produced at pyrolysis temperature ranging from 501–600 °C and derived from animal waste demonstrated significant effect on increasing soil pH in tea plantations by 9% and 12%, respectively. This study offers valuable insights into improving and ensuring the health and sustainability of tea plantations. [ABSTRACT FROM AUTHOR]

Soil acidification is a significant form of agricultural soil degradation, which is accelerated by irrational fertilizer application. Sweetpotato and wheat rotation has emerged as an important rotation system and an effective strategy to optimize nutrient cycling and enhance soil fertility in hilly areas, which is also a good option to improve soil acidification and raise soil quality. Studying the effects of different fertilization regimes on soil acidification provides crucial data for managing it effectively. An eight-year field experiment explored seven fertilizer treatments: without fertilization (CK), phosphorus (P) and potassium (K) fertilization (PK), nitrogen (N) and K fertilization (NK), NP fertilization (NP), NP with K chloride fertilization (NPK1), NP with K sulfate fertilization (NPK2), and NPK combined with organic fertilization (NPKM). This study focused on the soil acidity, buffering capacity, and related indicators. After eight years of continuous fertilization in the sweetpotato–wheat rotation, all the treatments accelerated the soil acidification. Notably, N fertilization reduced the soil pH by 1.30–1.84, whereas N-deficient soil showed minimal change. Organic fertilizer addition resulted in the slowest pH reduction among the N treatments. Both N-deficient (PK) and organic fertilizer addition (NPKM) significantly increased the soil cation exchange capacity (CEC) by 8.83% and 6.55%, respectively, compared to CK. Similar trends were observed for the soil-buffering capacity (pHBC). NPK2 increased the soil K+ content more effectively than NPK1. NPKM reduced the sodium and magnesium content compared to CK, with the highest magnesium content among the treatments at 1.60 cmol·kg−1. Regression tree analysis identified the N input and soil magnesium and calcium content as the primary factors influencing the pHBC changes. Structural equation modeling showed that the soil pH is mainly influenced by the soil ammonium N content and pHBC, with coefficients of −0.28 and 0.29, respectively. Changes in the soil pH in the sweetpotato–wheat rotation were primarily associated with the pHBC and N input, where the CEC content emerged as the main factor, modulated by magnesium and calcium. Long-term organic fertilization enhances the soil pHBC and CEC, slowing the magnesium reduction and mitigating soil acidification in agricultural settings. [ABSTRACT FROM AUTHOR]