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Fertilization regimes have been widely practiced to increase soil organic carbon (SOC) in Chinese farmland, but the findings of various studies are often widely divergent. Therefore, a comprehensive review of the impacts of fertilization regimes on SOC is needed. In this study, a meta-analysis based on 57 peer-reviewed articles was conducted to examine the effects of fertilization regimes on SOC in China. On average, the inorganic fertilizer combined with organic fertilizer regime (NPKOF) represented the most effective approach, increasing SOC by 42.6%; this was followed by the organic fertilizer regime (OF, 41.6%) and the inorganic fertilizer regime (NPK, 15.8%). Further analysis suggested that the effects of fertilization regimes were more pronounced in areas with relatively lower clay content, higher aridity index, longer experimental duration or higher soil pH. We also highlight the importance of considering local environmental factors (e.g., climate and soil conditions) in identifying appropriate fertilization regimes for maintaining soil health, mitigating greenhouse gas emissions while ensuring crop productivity. In conclusion, although NPK addition can significantly enhance SOC content, the combined application of inorganic with organic fertilizer is very important in maintaining and improving the current SOC content across China, especially in arid regions (e.g., Northwest, lower MAP regions and higher aridity index). [ABSTRACT FROM AUTHOR]

AbstractPhosphorus (P) limitation in acidic soils is well known and P-use and -recovery efficiency (PUE and PRE) is quite low. Rhizosphere-based P management has been considered as a means of enhancing PUE in acidic rice soils, but no clear dynamic study on this context. Rice was grown in pots using different P-sources [rock-phosphate (RP), single-super-phosphate (SSP), compost, P solubilizing bacteria (PSB), PSB + RP, PSB + compost, and compost + PSB + RP] in acidic Inceptisols (pH 4.31). Additionally, a micro-plot field experiment validated the results, using control, SSP, RP, PSB, and PSB + RP. Available-P (AvlP) and pH were analyzed every 10-days, while acid-phosphomonoesterases activity (PHA) and P-uptake in every 30-days until harvest. AvlP was peaked at 20 days after transplanting (DAT) and decreased until harvest. Compost + PSB + RP maintained significantly higher AvlP, soil pH and PHA, while root volume was highest in SSP throughout the growing period, and Soil pH showed an asymptotic trend. The P-content and uptake in biomass showed the highest peak at 60DAT and gradually declined until harvest. The effects of SSP and compost + PSB + RP on grain yield, chlorophyll concentration index (CCI), grain P content and uptake were comparable, but PUE and PRE were higher in compost + PSB + RP. Similar result was also observed in micro-plot field experiment, wherein grain yield and P uptake were comparable in SSP broadcast and PSB + RP. The study clearly shows that the combined application of PSB with RP, compost, or both in a 50% reduced amount can maintain higher AvlP in rice in acidic soil compared to full dose SSP while achieving a comparable yield. [ABSTRACT FROM AUTHOR]

In soils, pH stands as the main factor modulating bacterial communities' composition. However, most studies address its effects in bulk soils in natural systems, with few focusing on its effects in the rhizosphere of plants. Predicting pH effects in the rhizosphere is an important step towards successful microbiome manipulation, aiming to increase crop production. Here, we modulated an acidic soil's pH to four different ranges (4.7, 5.2, 7.5 and 8.2), while correcting for fertility differences among ranges, thus isolating pH effects from other physicochemical characteristics. Then, two crops with distinct metabolisms (maize and bean) were cultivated in a greenhouse experiment and the effects of pH and cover crops on the rhizosphere bacteriome after 90 days explored through 16S rRNA gene sequencing, aiming to characterize pH effects on the rhizosphere of two different plants across this gradient. Alpha diversity indexes (OTU richness and Shannon index) were statistically different with pH but not crop species, with an interaction among factors. For beta diversity, both pH and crop species were significant modulators of community composition, without an interaction, but pH effects were 2.5 times bigger than those of plant species. Additionally, strong and significant positive correlations were observed between pH and Bacteroidetes and Deltaproteobacteria, while Actinobacteria, Planctomycetes and Acidobacteria were negatively correlated with pH. Regarding OTUs, 27 and 46 were correlated with pH in maize and bean's rhizosphere, respectively, while 11 were shared between them. Altogether, these results provide valuable information on the isolated effect of pH in the rhizosphere of important crop plants, aiding future microbiome manipulation studies. [ABSTRACT FROM AUTHOR]

Manganese toxicity is a major obstacle to agriculture in acid soils. Dark pericarp disease (DPD) is a newly spread physiological disorder induced by excess Mn in litchi, leading to undesirable fruit appearance and substantial economic loss. In this work, broadcast of alkaline soil conditioner in winter, followed by foliar sprays of ascorbic acid and sulfur solution at fruit development, was adopted to examine the effect of these combinations on DPD alleviation in a litchi orchard, with DPD morbidities of 70~85% in recent ten years. The combination of soil conditioner broadcast and foliar water spray was used as the control. At harvest, DPD incidence was significantly decreased by sulfur spray (3.3 ± 1.0%) and slightly reduced by ascorbic acid spray (10.7 ± 8.0%) compared to the control (12.9 ± 7.6%). Soil pH and available Mn were significantly increased and reduced by the soil conditioner broadcast. Sulfur spray significantly inhibited Mn uptake but enhanced the accumulation of Mg, Ca, sugars and cyanidin-3-rutinoside in the pericarp, leading to improved fruit pigmentation. Antioxidase activities were regulated to resist Mn stress by sulfur spray. The spray of ascorbic acid could not mitigate DPD as expected, probably due to the dose used. Conclusively, this study provides a practicable approach to mitigate Mn phytoavailability in acid soils. [ABSTRACT FROM AUTHOR]

Aim: To quantify the role of soil fertility in the spatial variability of fire activity and to identify the mechanisms that drive this variability. Location: The five Mediterranean‐type climate regions of the world. Time Period: 2002–present. Major Taxa Studied: Terrestrial plants. Methods: We compiled remotely sensed data on fire activity, climate, net primary productivity and chemical soil properties for bioclimatically homogeneous zones within the five Mediterranean‐type climate regions of the world. Putative direct and indirect effects of the environmental variables on fire activity were evaluated through structural equation modelling. Results: Fire activity increased with net primary productivity, as expected for ecosystems with fuel‐limited fire regimes. Soil acidity and the concentration of exchangeable aluminium also increased fire activity, supporting the idea that low fertility promotes plant characteristics that favour fire initiation and spread. Main Conclusions: Our research supports a positive relationship between wildfires and low soil fertility in Mediterranean‐type climate regions across the globe. Therefore, soil fertility should be incorporated into models predicting future fires in a warming world. [ABSTRACT FROM AUTHOR]

In soils, pH stands as the main factor modulating bacterial communities’ composition. However, most studies address its effects in bulk soils in natural systems, with few focusing on its effects in the rhizosphere of plants. Predicting pH effects in the rhizosphere is an important step towards successful microbiome manipulation, aiming to increase crop production. Here, we modulated an acidic soil’s pH to four different ranges (4.7, 5.2, 7.5 and 8.2), while correcting for fertility differences among ranges, thus isolating pH effects from other physicochemical characteristics. Then, two crops with distinct metabolisms (maize and bean) were cultivated in a greenhouse experiment and the effects of pH and cover crops on the rhizosphere bacteriome after 90 days explored through 16S rRNA gene sequencing, aiming to characterize pH effects on the rhizosphere of two different plants across this gradient. Alpha diversity indexes (OTU richness and Shannon index) were statistically different with pH but not crop species, with an interaction among factors. For beta diversity, both pH and crop species were significant modulators of community composition, without an interaction, but pH effects were 2.5 times bigger than those of plant species. Additionally, strong and significant positive correlations were observed between pH and Bacteroidetes and Deltaproteobacteria, while Actinobacteria, Planctomycetes and Acidobacteria were negatively correlated with pH. Regarding OTUs, 27 and 46 were correlated with pH in maize and bean’s rhizosphere, respectively, while 11 were shared between them. Altogether, these results provide valuable information on the isolated effect of pH in the rhizosphere of important crop plants, aiding future microbiome manipulation studies.

Abstract Biochar incorporation into soil has shown potential, in enhancing nitrogen fertilizer (N-fertilizer) efficacy and soil organic carbon content (SOC). This study addresses a critical gap in the literature by investigating the effects of biochar addition over a seven-year period (2014–2020) on inorganic N, SOC, and pH in Haplic Luvisol. The research involved a rain-fed field experiment, with a crop rotation comprising spring barley, maize, spring wheat, and pea. Biochar, applied at the rates of 0, 10, and 20 t ha−1 in 2014, was reapplied to specific plots in 2018. Biochar was also combined with N-fertilizer at three level (N0, N1, and N2). Results showed a significant interactive influence of biochar and N-fertilizer combination on NO3 − and NH4 + contents. Intriguingly, the addition of 10 t biochar ha−1 consistently decreased soil inorganic N levels across most of the examined months. Increasing biochar application rates led to a significant rise in pH, establishing a clear, negative correlation between soil pH and inorganic N content. Biochar significantly increased SOC compared to the control, particularly after the reapplication in 2018. However, this effect showed a diminishing trend over time. The study suggests that incorporating biochar treatments may enhance N-fertilizer effectiveness. However, the long-term implications of biochar application with N-fertilizer on N mineralization are specific to individual soil and biochar combinations. Except the application of 20 t ha−1 biochar at N2 in 2019, biochar did not affect the crop yields. Studied soil properties, including those influenced by biochar had nuanced impact on different aspects of crop yield. Graphical Abstract

Soil plays a pivotal role in ecosystem health and agricultural productivity. This study focuses on a critical region for soil research, Kalmykia's central dry steppe zone in southern Russia, characterized by arid conditions and unique challenges. Our investigation aimed to evaluate the current state of soil properties and assess trace element accumulation within this environment. The region's distinctive characteristics, including being home to Europe's first desert, present a complex scenario for soil conservation and management. A thorough analysis of key physicochemical properties, including organic matter content, soil texture, pH levels, and the concentrations of trace elements (V, Cr, Co, Ni, Cu, Zn, Sr, and Pb) using established methodologies, was conducted. Our findings revealed several crucial insights into the soil conditions of this arid region. Soil samples predominantly consisted of Haplic Kastanozems Sodic, characterized by low organic carbon content (0.3-1.9%). Soil texture analysis indicated a predominantly light and medium loamy granulometric composition with a prevalence of sandy fractions. Soil pH values ranged from neutral (pH = 7.6-7.9) to slightly alkaline (pH = 8.0-8.4). Furthermore, the study provided the first assessment of soil conditions in residential areas of the Caspian Lowland's arid region. Notably, trace element analysis showed elevated concentrations of several metals, with Sr having the highest levels. Co, Cr, and Zn concentrations did not significantly increase compared to the background values. The results of this soil fertility evaluation hold significance for soil restoration and conservation efforts in this unique and fragile ecosystem. In conclusion, this study underscores the urgent need for soil monitoring and management practices to address soil degradation and desertification driven by overgrazing and erosion. Understanding the physicochemical properties and trace element dynamics in arid regions is essential for developing strategies to restore and conserve these valuable soils.

Aim: Soil nitrogen (N) cycling is critical to the productivity of terrestrial ecosystems. However, the impact of global change factors (GCFs) on the microbial mediators of N cycling pathways has yet to be synthesized, and it also remains unclear whether the response of the abundance of N-cycling genes can predict changes in their corresponding processes. Location: Global. Time period: 2000–2021. Major taxa studied: Archaea, bacteria. Methods: We synthesized 8322 paired observations of soil microorganisms related to N cycling from field experiments in which GCFs (climate change and nutrient addition) were manipulated. Results: We found that the abundance of soil microbes and most N-cycling genes were resistant to elevated CO2, experimental warming and water addition/reduction; however, N addition and the combination of N addition with other GCFs significantly increased the abundance of ammonia oxidizer bacteria (amoA-AOB). The results indicated that in steady-state (natural) conditions, the main factors driving the global abundance of soil bacteria, archaea and N-cycling genes varied in terms of the contributions of climatic and edaphic factors. However, upon manipulation of GCFs, the induced change in soil pH was the most essential factor associated with changes in the abundance of soil microbes and N-cycling genes. Notably, the changes in ammonia-oxidizing archaea (amoA-AOA) and amoA-AOB genes, in addition to genes involved in denitrification (nirS and nirK), were significantly correlated with the rates of their corresponding processes, but GCF-induced shifts in the potential nitrification rate (PNR) were explained well by changes in the abundance of the amoA-AOB gene under GCFs. Main conclusions: Our study highlights how ongoing GCFs impact the abundance of soil microbes and N-cycling genes, which might have a profound impact on terrestrial N cycling. Our field-based results provide new insights into the drivers of the abundance of soil microbes and N-cycling genes.

Extensive use of per- and polyfluoroalkyl substances (PFAS) in various industrial and consumer products in the past has led to their widespread distribution in the environment. PFAS contamination has become a major environmental and public health threat worldwide, especially in communities impacted by industrial, commercial, and military activities. In 2021, twelve soil samples were collected from three distinct site types in Brevard County, Florida, based on community concerns: background sites, primary-source sites, and secondary-source sites. These sites comprised samples collected from both residential and industrial/commercial areas. Ultra-high performance liquid chromatography-tandem mass spectrometry was used to identify and quantify PFAS in the samples. The results show that PFAS were present in all soil samples, with the lowest and the highest concentrations being in background and primary sites, respectively. Total PFAS concentrations in both primary and secondary sites were generally one-order of magnitude greater than those reported in background sites. Perfluorooctanesulfonic acid concentrations were the most predominant among the 34 species of PFAS detected in the samples, with concentrations ranging from 0.04 to 2.63 ​ng/g. Analysis of variance of PFAS data reveals significant difference among study sites, with greater diversity and concentrations near primary sources followed by secondary sites and background sites. The results also demonstrate that long-chained PFAS are significantly more abundant in these soils than short-chained PFAS. Overall, our results should help prioritize future sampling locations for a rapid and systematic identification of PFAS in soils.

Ageratina adenophora is an invasive weed species found in many countries. Methods to control the spread of this weed have been largely unsuccessful. Soil pH is the most important soil factor affecting the availability of nutrients for plant and impacting its growth. Understanding the mechanisms of the influence of soil pH on the growth of A. adenophora may help to develop effective control measures. In this study, we artificially changed the soil pH in pot experiments for A. adenophora. We studied the effects of acidic (pH 5.5), weakly acidic (pH 6.5), neutral (pH 7.2), and alkaline (pH 9.0) soils on the growth, availability of soil nutrients, activity of antioxidant enzymes, levels of redox markers in the leaves, and the structure and diversity of the rhizosphere microbiome. Soil with a pH 7.2 had a higher (47.8%) below-ground height versus soils of pH 5.5 at day 10; plant had a higher (11.3%) above-ground height in pH 7.2 soils than pH 9.0 soils at day 90; no differences in the fresh and dry weights of its above- and belowground parts, plant heights, and root lengths were observed in plants growing in acid, alkaline, or neutral pH soil were observed at day 180. Correspondingly, the antioxidant enzymes SOD (superoxide dismutase), POD (peroxidase), CAT (catalase) and redox markers GSH (glutathione) and MDA (malondialdehyde) were measured in the leaves. Significant differences existed in the activities of CAT and the levels of GSH between those growing in acidic and alkaline soils and those in neutral pH soil at day 90; however, only lower (36.8%) CAT activities in those grown at pH 5.5 than those grown at pH 7.2 were found at day 180. Similarly, significant differences in available P (16.89 vs 3.04 mg Kg−1) and total K (3.67 vs 0.96 mg Kg−1), total P (0.37 vs 0.25 g Kg−1) and total N (0.45 vs 1.09 g Kg−1) concentrations were found between the rhizosphere soils of A. adenophora grown at pH 9.0 and 7.2 at day 90; no such differences were seen at day 180. High throughput analyses of the 16S rRNA and ITS fragments showed that the rhizosphere microbiome diversity and composition under different soil pH conditions changed over 180 days. The rhizosphere microbiomes differed in diversity, phylum, and generic composition and population interactions under acid and alkaline conditions versus those grown in neutral soils. Soil pH had a greater impact on the diversity and composition of the prokaryotic rhizosphere communities than those of the fungal communities. A. adenophora responded successfully to pH stress by changing the diversity and composition of the rhizosphere microbiome to maintain a balanced nutrient supply to support its normal growth. The unusual pH tolerance of A. adenophora may be one crucial reason for its successful invasion. Our results suggest that attempts use soil pH to control its invasion by changing the soil pH (for example, using lime) will fail.

BackgroundPlasmodiophora brassicae is an ever-increasing threat to cruciferous crop production worldwide.Aims and methodsThis study investigated the impact of pre-soil fumigation with ammonium bicarbonate (N) and lime (NB) to manage clubroot disease in Chinese cabbage through 16S rRNA gene amplification sequencing.ResultsWe found that soil fumigation with N and NB suppressed disease incidence by reducing the soil acidity and population of P. brassicae in the rhizosphere. Minimum disease incidence and maximum relative control effect of about 74.68 and 66.28% were achieved in greenhouse and field experiments, respectively, under the combined application of ammonium bicarbonate and lime (LNB) as compared with N, NB, and control (GZ). Microbial diversity analysis through Miseq sequencing proved that pre-soil fumigation with N, NB, and LNB clearly manipulated rhizosphere microbial community composition and changed the diversity and structure of rhizosphere microbes compared with GZ. Bacterial phyla such as Proteobacteria, Bacteriodetes, and Acidobacteria and fungal phyla including Olpidiomycota and Ascomycota were most dominant in the rhizosphere of Chinese cabbage plants. Soil fumigation with N and NB significantly reduced the abundance of clubroot pathogen at genus (Plasmodiophora) level compared with GZ, while decreased further under combined application LNB. Microbial co-occurrence network analysis showed a highly connected and complex network and less competition for resources among microbes under combined application LNB.ConclusionWe conclude that for environmentally friendly and sustainable agriculture, soil fumigation with combined ammonium bicarbonate and lime plays a crucial role in mitigating Chinese cabbage clubroot disease by alleviating soil pH, reducing pathogen population, and manipulating the rhizosphere microbiome.

The article analyzes soil organic carbon (SOC) content of in Poland from 2015 to 2021. The research aims to determine SOC levels and their dependence on soil agronomic categories and drought intensity. Soil samples from 1011 farms across 8 Polish voivodships were collected for analysis, all from the same agricultural plots. SOC determination was conducted using the Tiurin method. The results indicate a low SOC content nationwide (0.85-2.35%). Heavy soils exhibited higher SOC accumulation compared to light soils. Moreover, significant drought impact led to decreased SOC content in affected regions. Scientific evidence underscores a declining trend in organic carbon stock within agricultural soils, attributed to natural soil changes and unsustainable management practices. This decline is concerning given the crucial role of SOC in soil health, quality, and crop productivity. Therefore, it is imperative to monitor and address areas with low SOC levels to enhance SOC abundance. Furthermore, when used as a whole-cell biocatalyst in a low-cost upflow MFC, the Morganella morganii-rich SF11 consortium demonstrated the highest voltage and power density of 964.93±1.86 mV and 0.56±0.00 W/m3, respectively. These results suggest that the SF11 bacterial consortium has the potential for use in ceramic separator MFCs for the removal of penicillin and electricity generation.

The concentration of mineral nutrients in plants is associated with bioavailabilities of soil mineral nutrients, which are regulated by various soil physio-chemical properties. A pot experiment was conducted to investigate the effects of soil type on grain and straw zinc (Zn), iron (Fe) and selenium (Se) concentrations of wheat/Amblyopyrum muticum and wheat/Triticum urartu doubled haploid lines. A set of 42 treatments in a factorial combination with 21 genotypes and two soil types collected from Ngabu and Chitedze Research Stations in Malawi was laid in a randomised complete block design (RCBD) in three replicates. Pre-experiment soil Zn and Fe were extracted using DTPA extraction method followed by analysis with inductively coupled plasma-mass spectrometry (ICP-MS). Aqua-regia hotplate acid digestion was used to extract soil Se and analysis was done using ICPM-MS. Grain and straw samples were digested using nitric acid digestion (HNO3) and analysed using ICP-MS. Soil analysis results showed that the two soils had the same textural class (Sandy clay loam), but different mineral concentrations, pH levels and percentage organic matter. Analysis of variance revealed a ~two-fold higher Zn concentration in grains grown in low pH, high Zn soils (Chitedze soils) compared to grains grown in high pH, low Zn soils (Ngabu soils). Variation in grain Zn concentration was associated with the genotypes (p = 0002), soil type (p =

The hypothesis that soil anion storage capacity (ASC) directly influences the response of onion yield to soil Olsen P status was tested. Onions were grown to maturity in three different soils in the same tunnel house. Each soil received three rates of phosphorus (P) fertiliser 1 month before planting, and at planting soil ASC and Olsen P status was measured. Although bulb yield increased with Olsen P (over the range 15–95 μg g−1), ASC (which varied from 10 to 70%) had no influence on this response. This supports recent findings with young onions grown in small pots, but contradicts previous advice to vegetable growers. The results show that low to moderate soil Olsen P values and low initial availability of N, slow early plant growth and development. Delays in maturity due low P input may allow growth to catch up, at least partially, later in the season. This has implications for the design and execution of field experiments to test P fertilisers for onions and suggests that visible responses to P fertiliser in young onion crops may be misleading. [ABSTRACT FROM AUTHOR]

Biochar incorporation into soil has shown potential, in enhancing nitrogen fertilizer (N-fertilizer) efficacy and soil organic carbon content (SOC). This study addresses a critical gap in the literature by investigating the effects of biochar addition over a seven-year period (2014–2020) on inorganic N, SOC, and pH in Haplic Luvisol. The research involved a rain-fed field experiment, with a crop rotation comprising spring barley, maize, spring wheat, and pea. Biochar, applied at the rates of 0, 10, and 20 t ha−1 in 2014, was reapplied to specific plots in 2018. Biochar was also combined with N-fertilizer at three level (N0, N1, and N2). Results showed a significant interactive influence of biochar and N-fertilizer combination on NO3− and NH4+ contents. Intriguingly, the addition of 10 t biochar ha−1 consistently decreased soil inorganic N levels across most of the examined months. Increasing biochar application rates led to a significant rise in pH, establishing a clear, negative correlation between soil pH and inorganic N content. Biochar significantly increased SOC compared to the control, particularly after the reapplication in 2018. However, this effect showed a diminishing trend over time. The study suggests that incorporating biochar treatments may enhance N-fertilizer effectiveness. However, the long-term implications of biochar application with N-fertilizer on N mineralization are specific to individual soil and biochar combinations. Except the application of 20 t ha−1 biochar at N2 in 2019, biochar did not affect the crop yields. Studied soil properties, including those influenced by biochar had nuanced impact on different aspects of crop yield. Article Highlights: Biochar obtained from mixed paper fiber sludge and the grain husks resulted in a significant increase of SOC over 7 years. Biochar aging resulted in a decrease in pH one year after its application in 2015 and 2019. The combination of N-fertilizer with biochar caused an improvement in soil inorganic N content in 2014 and reapplication in 2018. [ABSTRACT FROM AUTHOR]

Conventional aerobic methanotrophs oxidize methane (CH4) and covert CH4-derived carbon (C) into biomass at the oxic-anoxic interface of inundated rice paddy fields, playing indispensable role in mitigating greenhouse gas emissions and loss of organic C from methanogenesis. Two phylogenetically distinct groups of methanotrophs, type I (γ-proteobacteria) and type II (α-proteobacteria) methanotrophs, often co-exist in rice paddy soil and compete for CH4 biotransformation. Since these two methanotrophic groups also possess differential kinetics of CH4 oxidation and pathways of C assimilation, the consequence of their niche differentiation and metabolic differences in soil is expected to affect the CH4 oxidation rate and C conversion efficiency. Here, we examined the microbiology, chemistry, and CH4 metabolism in 24 geographically different paddy soils, covering four climate zones of eastern China. High-throughput sequencing of pmoA gene displayed a clear separation of in situ methanotrophic compositions between temperate (warm and mid-temperate) and warmer (subtropics and tropics) climate zones, likely driven by soil pH. Both methanotrophic groups were detected in soils but proportions of type I methanotrophs increased in temperate soils of higher pH (accounting for 76.1 ± 12.4% and 44.1 ± 14.8% in warm temperate and mid-temperate, respectively). Type II methanotrophs prevailed in warmer zones (accounting for 66.2 ± 21.6% and 70.5 ± 12.1% in tropics and subtropics, respectively) where soils were more acidic. Higher incorporation of 13C for synthesis in C14+C16 PLFAs (63.1–93.4% of total production of 13C-PLFAs) was found based on microcosm incubation, reflecting type I methanotrophs dominated the CH4 assimilation in paddy soils. Particularly, temperate soils with increased proportions of type I methanotrophs showed higher CH4 oxidation rate and C conversion efficiency. Collectively, this study depicts a continental-scale disparity of methanotrophic dynamics that tightly associates with consequence of niche differentiation of different types of methanotrophs and highlights the importance of microbiological control to maximize the rate and efficiency of methanotrophy. [ABSTRACT FROM AUTHOR]

Winter canola (Brassica napus L.) is a potential alternative to winter wheat in Oklahoma rotation systems as a means to overcome the negative impacts of continuous wheat systems. However, its performance may suffer in the acid soils that are common to intensive agriculture systems in the southern Great Plains region. The objective of this study was to quantify the impact of soil pH and Al3+ concentration on winter canola production. Two field trials were conducted in 2016 and 2017 across four different locations in central Oklahoma to evaluate the performance of four canola cultivars in soils with a range of pH from 4.0 to 8.0. Yield, soil pH, and Al3+ concentrations were measured from each plot to study the relationships between these variables. At all but one location, soil pH and Al3+ concentrations were inversely related and when data across these locations were combined, Al3+ concentrations decreased as pH increased to a critical value of 4.8 (r² = 0.83). In general, it was found that yield decreased linearly as pH decreased below 5.8 (r² = 0.75) and increased linearly as Al3+ concentrations decreased below 87 mg kg-1 (r² = 0.73). Above these thresholds, yield was unrelated to pH or Al3+ concentrations. It was also observed that at one location with very low naturally occurring Al3+, high canola yields were achievable even in low soil pH. Therefore, Al3+ concentrations may be a better indicator of the effects of acidic soils on winter canola yields than pH values alone. [ABSTRACT FROM AUTHOR]

This article shows the details of the design and implementation of a wireless sensor network (WSN) system, through the use of an Arduino prototyping platform and Lora communication modules, to collect soil humidity, temperature, and PH data in a fruit crop. Data is captured and stored to generate a time series of data to improve decision-making when variation in the essential nutrient application was required. The case study was a parcel in the village of Piedra Larga, in the municipality of Ciénega - Boyacá, where the WSN was deployed that collects the data and allow a visual representation to compare with reference levels and determine the nutrient level requirements. An irrigation monitoring system is implemented by applying artificial intelligence to assist the farmer with two key tasks: i) the activation of the drip irrigation system seeking the efficient use of water, and ii) improving fruit production by controlling the percentage of nutrients. The mobile application shows real-time data monitoring of environmental and soil variables, for the analysis of results and the concentrations of the nutrient mixture together with the drip control to be applied to the crop. An optimal estimation of the required nutrient concentrations was estimated from a neural network to simplify and improve the efficiency of the farmer's agricultural activities, such as saving water consumption by 40% and improving fruit production by up to a 30% [ABSTRACT FROM AUTHOR]

This study assessed the effects of rainfall on soil physico-chemical properties (pH, moisture, temperature, Nitrogen value, Phosphorus value and Potassium value) of MD2 pineapple cultivation on marginal soil, and also investigated correlation between rainfall and soil physico-chemical properties based on IoT-based monitoring. Agromon Smart Agriculture and NPK Sensors (Agromon) that is equipped with a Sigfox-based wireless transmitter was used to provide real-time marginal soil properties data from an experimental MD2 pineapple field plot in UiTM Sarawak. Rainfall data between March and July 2021 for Samarahan Rainfall Station were obtained from Department of Irrigation and Drainage, Sarawak (DID). Soil properties data were transmitted from field plot gateway to the nearest Sigfox base station in Santubong, and subsequently to SATU dashboard server in order to be accessible to all users. Agromon demonstrated the capability of IoT system in monitoring selected soil properties across favored and unfavored weather conditions. Pineapple farmers can make timely and cost-effective farm operation decision anywhere to optimize plant vigor and therefore, improve yield. [ABSTRACT FROM AUTHOR]

Lilium growth is severely impeded by continuous cropping, and crop rotation is essential to reducing the detrimental effects of monocultures. Soil (0–20 cm) was collected in three Lilium cropping patterns in Longshan County, Hunan Province, including continuous Lilium cropping (Lilium), corn upland rotation with Lilium (Corn), and paddy rotation with Lilium (Rice). Using Illumina high-throughput sequencing technology, the fungal ribosomal DNA internal-transcribed spacer 1 (ITS1) was examined to evaluate the features of soil fungi communities among three cropping patterns. Crop rotation has an impact on soil properties and the microbial community. Rice soil has a significantly higher pH than Lilium and corn soil, while corn and rice soil have a greater total nitrogen and total phosphorus content than Lilium soil. Rotation cropping clearly shifted the fungi community diversity based on the results of principal coordinate analysis (PCoA) and nonmetric multidimensional scaling (NMDS). Ascomycota was the most prevalent phylum, with the highest levels in Lilium soil. Genetic analysis revealed that paddy rotation led to a clear reduction in or non-detection of eight potentially pathogenic fungal genera and a noticeable accumulation of eight beneficial fungal genera compared to Lilium continuous cropping. Fungi communities and their abundant taxa were correlated with soil pH and nutrients. Altogether, we propose that rice rotation, with its ability to mitigate soil acidification, reducing pathogenic and accumulating beneficial communities, may be an effective strategy for alleviating the continuous cropping barrier. [ABSTRACT FROM AUTHOR]

Biochar application has the potential for mitigating N2O emissions from agricultural soils and has been suggested as a management practice to ameliorate soil fertility and increase crop productivity. Nevertheless, the influence of biochar addition on N2O emissions from soils with different pH levels is not yet clear, which results in a poor understanding of the mechanisms regarding biochar application to soil N2O mitigation. A 40-day incubation experiment was carried out in the present study to investigate the impact of biochar on N2O emissions from soils with different natural pH. Four treatments (control, nitrogen fertilizer application, biochar amendment, and N plus biochar amendment) were set up separately in soils with three different natural pH levels (acidic vegetable soil, neutral rice soil, and alkaline soil). Our results showed that adding biochar significantly decreased N2O emissions by 20.8% and 47.6% in acidic vegetable soil for both N and no N addition treatments, respectively. For neutral and alkaline soils, the reduction of N2O emissions by biochar amendment was only significant for N addition treatments in alkaline soil. Soil pH and NO3−-N concentration were significantly affected by biochar amendment (soil pH increased by 1.43–1.56, 0.57–0.70, and 0.29–0.37 units for acidic vegetable soil, neutral rice soil, and alkaline soil, respectively). Thus, biochar amendment could be used as an effective management practice for mitigating N2O emissions from acidic and alkaline soils. [ABSTRACT FROM AUTHOR]

Emissions of nitrous oxide (N2O), a potent greenhouse gas, from farmland have been recognized to be affected by soil pH and nitrogen (N) fertilizer application. However, the interactive effects of soil pH and N fertilizer type on N2O emissions and their influencing mechanism are poorly understood. A field experiment was conducted to elucidate the impacts of synthetic fertilizer and manure on soil properties and N2O fluxes along a soil acidity gradient (soil pH = 6.8, 6.1, 5.2, and 4.2) in the Huai River Basin, and a lab incubation experiment was performed to understand the underlying mechanisms of changed N2O flux. Low soil pH inhibited the ammonia-oxidizing bacteria abundance and thereby reduced the N2O production by nitrification under both synthetic fertilizer and manure application. The N2O production by denitrification was also reduced with declining soil pH, likely due to the decreased nirS and nirK abundances, and lower NO3−. However, low soil pH reduced the nosZ abundance and increased (nirS + nirK)/nosZ ratio, resulting in the increased N2O/(N2O + N2) ratio. Finally, with the decreased nitrification and denitrification, soil N2O emission was significantly reduced with declining soil pH regardless of fertilizer types. Compared with synthetic fertilizer, manure application increased soil nutrients (total N, dissolved organic C, and NO3−), nirK abundance, and (nirS + nirK)/nosZ ratio in the soils with pH of 5.2 and 4.2, thereby promoting N2O production by denitrification and N2O/(N2O + N2) product ratio in acidic soils. Consequently, soil N2O emission was increased with manure application in acidic soils. This study provides novel insight and improves our understanding of how soil pH regulates nitrification, denitrification, and N2O emissions from soils amended with chemical fertilizer and manure, which gives guidance on developing N management strategies for sustainable production and N2O mitigation in acid soils. [ABSTRACT FROM AUTHOR]

Soil plays a pivotal role in ecosystem health and agricultural productivity. This study focuses on a critical region for soil research, Kalmykia's central dry steppe zone in southern Russia, characterized by arid conditions and unique challenges. Our investigation aimed to evaluate the current state of soil properties and assess trace element accumulation within this environment. The region's distinctive characteristics, including being home to Europe's first desert, present a complex scenario for soil conservation and management. A thorough analysis of key physicochemical properties, including organic matter content, soil texture, pH levels, and the concentrations of trace elements (V, Cr, Co, Ni, Cu, Zn, Sr, and Pb) using established methodologies, was conducted. Our findings revealed several crucial insights into the soil conditions of this arid region. Soil samples predominantly consisted of Haplic Kastanozems Sodic, characterized by low organic carbon content (0.3-1.9%). Soil texture analysis indicated a predominantly light and medium loamy granulometric composition with a prevalence of sandy fractions. Soil pH values ranged from neutral (pH = 7.6-7.9) to slightly alkaline (pH = 8.0-8.4). Furthermore, the study provided the first assessment of soil conditions in residential areas of the Caspian Lowland's arid region. Notably, trace element analysis showed elevated concentrations of several metals, with Sr having the highest levels. Co, Cr, and Zn concentrations did not significantly increase compared to the background values. The results of this soil fertility evaluation hold significance for soil restoration and conservation efforts in this unique and fragile ecosystem. In conclusion, this study underscores the urgent need for soil monitoring and management practices to address soil degradation and desertification driven by overgrazing and erosion. Understanding the physicochemical properties and trace element dynamics in arid regions is essential for developing strategies to restore and conserve these valuable soils. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to realize the rapid estimation of soil pH in tobacco field on the regional scale. [Method] 296 tobacco field soils in Sichuan province were studied. The spectral reflectance of 390 - 2500 nm band of farmland soil was obtained by hyperspectral imaging technology. The effects of 12 spectral preprocessing methods, 2 characteristic band screening methods and 4 modeling methods on the accuracy of the hyperspectral estimation model of soil pH in tobacco field were systematically studied. [Result] In the range of 600 - 2500 nm, the spectral reflectance curves of different pH were obviously different. The accuracy of the estimation model was improved after single and combination preprocessing of the original spectrum. Among them, the first derivative (Dl) combined with standard normal variate (SNV) was the best spectral preprocessing method. A total of 93 soil pH characteristic bands were selected by competitive adaptive reweighted sampling (CARS) algorithm, which were mainly concentrated in the near infrared band 800 - 2500 nm. Both kernel ridge regression (KRR) and support vector machine (SVM) could obtain better estimation accuracy than partial least square regression (PLSR) and ridge regression (RR), regardless of spectral features obtained by all-band spectrum or principal component analysis dimension reduction. However, the estimation accuracy of PLSR and RR models was higher than that of KRR and SVM models in the feature bands screened by CARS. Based on Dl-SNV preprocessing method, the PLSR estimation model of soil pH established by using CARS screening characteristic bands had high accuracy, the coefficient of determination of model validation set was 0. 758, the root mean square error was 0. 555, and the residual prediction deviation was 2. 034. [Conclusion] It is feasible to use hyperspectral imaging technology to estimate the pH of tobacco field with high accuracy at regional scale, and the pH can be estimated by D1-SNV-CARS -PLSR model. [ABSTRACT FROM AUTHOR]

Soil environments are inhabited by microorganisms adapted to its diversified microhabitats. The metabolic activity of individual strains/populations reflects resources available at a particular spot, quality of which may not comply with broad soil characteristics. To explore the potential of individual strains to adapt to particular micro-niches of carbon sources, a set of 331 Actinomycetia strains were collected at ten sites differing in vegetation, soil pH, organic matter content and quality. The strains were isolated on the same complex medium with neutral pH and their metabolites analyzed by UHPLC and LC-MS/MS in spent cultivation medium (metabolic profiles). For all strains, their metabolic profiles correlated with soil pH and organic matter content of the original sites. In comparison, strains phylogeny based on either 16S rRNA or the beta-subunit of DNA-dependent RNA polymerase (rpoB) genes was partially correlated with soil organic matter content but not soil pH at the sites. Antimicrobial activities of strains against Kocuria rhizophila, Escherichia coli , and Saccharomyces cerevisiae were both site- and phylogeny-dependent. The precise adaptation of metabolic profiles to overall sites characteristics was further supported by the production of locally specific bioactive metabolites and suggested that carbon resources represent a significant selection pressure connected to specific antibiotic activities. [ABSTRACT FROM AUTHOR]

Leaf manganese (Mn) concentration has been used as a proxy for root exudation and phosphorus (P) uptake under controlled conditions, but there are limited field studies that confirm its validity. On an alkaline, P-poor soil, four lentil cultivars ('Samos', 'Thessaly', 'Flip', 'Algeria') received two P rates (0 and 26.2 kg P ha−1), for two growing seasons, to study whether aboveground assessments [leaf P, Mn, phenolic concentration (TPhe)] can approximate rhizosphere physiological traits related to P acquisition [soil acidification (ΔpH), arbuscular mycorrhizal fungi (AMF) colonisation, acid phosphatase activity (APase)]. Phosphorus addition had no effect on the determined traits. Cultivars differed in leaf P, Mn, TPhe and AMF, but there was no clear pattern relating aboveground traits to rhizosphere traits related to P acquisition, thus not confirming that leaf Mn can be a proxy of root exudation. Of three growth stages [V 7–8, R1 (first bloom), R4 (flat pod)], R1 seemed to be critical, showing the highest leaf P, ΔpH, AMF and TPhe. Precipitation and temperatures over the growing season were determinants of lentil responses affecting rhizosphere activity, soil P availability and finally leaf traits. In conclusion, in lentil on alkaline and P-limiting soils, high leaf Mn and phenolic concentration are not reliable indicators of rhizosphere P-acquiring mechanisms. In four lentil cultivars, under two phosphorus (P) levels (0 and 26.2 kg P ha−1), in an alkaline, P-poor soil, rhizosphere physiological traits related to P acquisition mechanisms and putative leaf proxies (P, manganese and phenolic concentration) were assessed. Our results indicated that the soil–root complexity in phosphorus acquisition mechanisms cannot be assessed by a single rhizosphere trait nor approximated by a single leaf trait. [ABSTRACT FROM AUTHOR]

To evaluate the effects of biochar on pH buffering capacity (pHBC) of paddy soils, rice straw biochar (RC) was modified by hydrogen peroxide (H2O2) and nitric acid/sulphuric acid (HNO3/H2SO4), respectively, and then added to the paddy soils developed from sandy Ultisol, clay Ultisol and granite Ultisol at the same proportion. After submerging and draining incubation, soil pHBC, soil pH and the available cadmium (Cd) extracted with calcium chloride were determined. The results indicated that the two modified biochars effectively promoted pHBC of three paddy soils and HNO3/H2SO4 modified biochar (HNO3/H2SO4-RC) led to greater increase in soil pHBC. Compared with control, HNO3/H2SO4-RC apparently increased pHBC of the paddy soils from sandy Ultisol, clay Ultisol and granite Ultisol by 32.7%, 37.4% and 25.3%, respectively. Correspondingly, soil pH increased by 1.59, 1.15 and 0.88 units, and the available Cd decreased by 74.1%, 67.5% and 75.0% in the paddy soils due to the incorporation of HNO3/H2SO4-RC. HNO3/H2SO4 modification significantly increased the carboxyl groups on the surface of RC. The dissociation of these functional groups produced a large number of organic anions, which could consume exogenous protons, and thus retarding the decline of soil pH and decreased soil available Cd. [ABSTRACT FROM AUTHOR]

The concentration of mineral nutrients in plants is associated with bioavailabilities of soil mineral nutrients, which are regulated by various soil physio-chemical properties. A pot experiment was conducted to investigate the effects of soil type on grain and straw zinc (Zn), iron (Fe) and selenium (Se) concentrations of wheat/Amblyopyrum muticum and wheat/Triticum urartu doubled haploid lines. A set of 42 treatments in a factorial combinationwith 21 genotypes and two soil types collected fromNgabu and Chitedze Research Stations in Malawi was laid in a randomisedcompleteblockdesign (RCBD) in three replicates. Pre-experiment soil Zn and Fe were extracted using DTPA extraction method followed by analysis with inductively coupled plasma-mass spectrometry (ICP-MS). Aqua-regia hotplate acid digestion was used to extract soil Se and analysis was done using ICPM-MS. Grain and straw samples were digested using nitric acid digestion (HNO3) and analysed using ICP-MS. Soil analysis results showed that the two soils had the same textural class (Sandy clay loam), but different mineral concentrations, pH levels and percentage organic matter. Analysis of variance revealed a ~two-fold higher Zn concentration in grains grown in low pH, high Zn soils (Chitedze soils) compared to grains grown in high pH, low Zn soils (Ngabu soils). Variation in grain Zn concentrationwas associated with the genotypes (p = 0002), soil type (p = <0.0001), and their interaction (p = 0.035). Grain Fe was 1.3-fold higher in low pH than in high pH soils, and itwas influenced by genotypes (p = < 0.0001) and soil type (p = <0.0001). Grain Se was highly associated with soil type (p = <0.0001), and it was 30-fold higher in high pH than in low pH soils. Straw Zn was generally higher in plants grown in Chitedze soils than Ngabu soils, whilst strawSewas higher in plants grown in Ngabu soils than Chitedze soils. The findings demonstrate the significance of soil physio-chemical properties for mineral accumulation and distribution to plant parts, thus informing future breeding programs on important considerations on crop genetic biofortification with the three mineral elements. [ABSTRACT FROM AUTHOR]

There is growing concern regarding cadmium (Cd) exposure through rice consumption. Compared with alternate wetting and drying (AWD), continuous flooding (CF) is usually considered as an effective approach for reducing Cd enrichment in rice but increases the risk of pollution from arsenic (As). In this study, the field trial was conducted to investigate remediation effects of two water management (CF and AWD) techniques on Cd pollution in rice in typical japonica rice cultivation areas with varied soil pH levels. The results indicate that soil pH was a crucial factor in regulating CF-mediated Cd/As accumulation and migration in rice plants, and grains at all stages of rice growth. In acidic fields, compared with AWD, the use of CF reduced the accumulation of Cd in plants during the tillering stage; CF during the milk stage promotes the risk of contamination of Cd in rice grains and any form of As in plants and inhibits the content of any forms of As in grains. During the mature stage, CF reduced the levels of Cd in the plants and grains while promoting the accumulation of As(V) and total As(T-As) in plants and As(III) in grains. In alkaline fields, compared with AWD, CF during the tillering stage promoted the accumulation of various forms of As in plants. During the milk stage, CF increased and decreased the Cd content in plants and grains, respectively, and reduced the accumulation of T-As in plants and As(III) in grains; during the mature stage, CF promoted the accumulation of Cd in plants and grains, induced the accumulation of T-As plants, and inhibited the accumulation of any form of As in grains. From the perspective of food safety, the impact of CF conditions on the accumulation of Cd and As in rice from acidic fields exhibited a pattern of reduction in Cd and increase in As during the maturity period, as compared to that on the AWD. Conversely, CF increased the Cd risk while simultaneously reducing the As accumulation in rice grains to a safe level in alkaline fields. CF is not recommended as a remediation strategy for Cd pollution in rice in low Cd pollution areas, but it can be considered as a potential strategy for As pollution remediation in rice in alkaline fields with low Cd pollution. [ABSTRACT FROM AUTHOR]

The red ginger plant is a type of rhizome plant which is one of the spices that are needed in Indonesia. The number of requests for red ginger requires the right planting media composition. Charcoal husks and manure are often used as mixed materials, especially those that cultivate plants in the bottom or polybags. An important parameter in the farming system is Electrical Conductivity (EC), temperature and pH. The degree of acidity or pH of the soil is very influential on the growth of a plant with a value between 6.5 to 7.5. The room temperature for red ginger plants is good with a range of 22-35°C. The TDS meter value in PDAM water is good at 100 ppm but the smaller the TDS value the better the water conductivity. The results of the sample testing 1, 2 and 3 of the soil pH value are at 5.9 to 6.4, this has a large impact of plant nutrient not available, so that Plant growth is disrupted. The TDS value is in the value of 87 to 95 shows the conductivity of water during the trial period in good condition. The temperature value of the space is in the range of 20-34°C which the temperature value is in the right condition. Making IoT-Based Application in Red Ginger Plants can help find out the good value of water conductivity, room temperature and soil pH in planting red ginger plants that can be monitored through the application.

Aim of study: To calculate Cd concentration in cocoa plants and evaluate its relationship with available Cd and other soil properties. Area of study: Almirante, Bocas del Toro province, Panama, in 2020-2021. Material and methods: The study was carried out in 21 plots of eight cocoa-producing farms. The total area of each sampled plot was 300 m2. Soil samples were taken at a depth of 30 cm, and samples of the leaves and fruits of cocoa trees were also taken. Descriptive statistics and correlation analyses were carried out for soil variables and Cd in plants. The relationship between bioavailable Cd and soil physicochemical variables and between soil variables and Cd in plants was evaluated. Multiple linear regression was performed using the backward selection method. Main results: The pH was acidic (5.1) and the organic matter content of the soil was greater than 3%, suitable for immobilizing Cd from the soil. Total and bioavailable Cd averaged 0.10 mg kg-1 and 0.02 mg kg-1 respectively. The Cd levels in cocoa leaves exceeded the recommended levels of 0.5 mg kg-1. The Cd concentration in the cocoa bean was low (0.25 mg kg-1). Research highlights: The levels of bioavailable Cd found do not exceed the United States Environment Agency toxic limits in soil. The level of Cd found in the cocoa bean is below the limit of 0.8 mg kg-1 which is taken as a reference for chocolate, with total dry matter content ≥ 50% of the CODEX Alimentarius.

Drought stress and acid soil pH are a form of abiotic stress on acid-dry land. Actinomycetes are a group of transitional microbes that have benefits as bioprotectants, biostimulators, and biofertilizers. This study aimed to determine the optimum growth environment for Actinomycetes at various incubation temperatures (25, 30, 35, and 40 ℃) and media pH (5, 6, 7, 8, and 9) and prove its effectiveness on mustard plants when given drought stress, and increase in acid soil pH. The research was conducted in the LOB greenhouse of PT Great Giant Pineapple using two factors, namely Actinomycetes (F22, F26, F34, F39, and F47) and irrigation (watered and not watered). Observations included Actinomycetes population (CFU mL-1), plant response (percentage of stress, death, survival, recovery), plant growth (plant length, number of leaves, root length), plant production (fresh weight), soil pH, and soil organic matter. Results of this study showed that Actinomycetes F22 gave the highest total population (107 CFU mL-1), and the P4K1, P4K2, and P2K2 treatment combination gave the best results on the observed parameters.

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

The ongoing acidification of soil poses a significant threat to the proper functioning of various ecosystems worldwide. Silicate rock dusts (RD) are increasingly amended to acid soils to restore their pH, but the acid neutralising capacity (ANC) and dissolution rate of these products are highly variable and lack proper assessment protocols. It is expected that pH-dependent RD ANCs and dissolution rates dictate the pH increase in soils depending on the initial pH and pH buffer power of the soil. This study addressed these questions by comparing and validating three accelerated weathering tests for their capacity to predict the gradual liming effects in a two-year outdoor mesocosm. Five commercial RDs (two basalts, phonolite, foidite, and trachy-andesite) were tested in four acidified forest soils varying in initial pH, in texture and associated pH buffer power. First, RD dissolution was measured in aqueous batch renewal systems during one year at various starting pH (3.5, 4.5, and 5.5) and constant temperatures (20 °C, 37 °C, and 65 °C). These showed that the ANCs of RDs exhibit a fast fraction (half-life 100 years depending on the starting pH of the soil, its pH buffer power, the RD mineralogy (XRD based) and its specific surface area. This study shows that the dissolution and ANC of RD can be most pragmatically predicted with a series of lime-calibrated soil-RD suspension tests of maximally two months.

Abstract Agricultural production is severely limited by an iron deficiency. Alkaline soils increase iron deficiency in rice crops, consequently leading to nutrient deficiencies in humans. Adding iron to rice enhances both its elemental composition and the nutritional value it offers humans through the food chain. The purpose of the current pot experiment was to investigate the impact of Fe treatment in alkaline (pH 7.5) and acidic (pH 5.5) soils to introduce iron-rich rice. Iron was applied to the plants in the soil in the form of an aqueous solution of FeSO4 with five different concentrations (100, 200, 300, 400, and 500 mM). The results obtained from the current study demonstrated a significant increase in Fe content in Oryza sativa with the application of iron in both alkaline and acidic pH soils. Specifically, Basmati-515, one of the rice cultivars tested, exhibited a notable 13% increase in iron total accumulation per plant and an 11% increase in root-to-shoot ratio in acidic soil. In contrast to Basmati-198, which demonstrated maximum response in alkaline soil, Basmati-515 exhibited notable increases in all parameters, including a 31% increase in dry weight, 16% increase in total chlorophyll content, an 11% increase in CAT (catalase) activity, 7% increase in APX (ascorbate peroxidase) activity, 26% increase in POD (peroxidase) activity, and a remarkable 92% increase in SOD (superoxide dismutase) in acidic soil. In alkaline soil, Basmati-198 exhibited respective decreases of 40% and 39% in MDA and H2O2 content, whereas Basmati-515 demonstrated a more significant decrease of 50% and 67% in MDA and H2O2 in acidic soil. These results emphasize the potential for targeted soil management strategies to improve iron nutrition and address iron deficiency in agricultural systems. By considering soil conditions, it is possible to enhance iron content and promote its availability in alkaline and acidic soils, ultimately contributing to improved crop nutrition and human health.

The acidification of agricultural soils should be avoided, and low pH soils should be corrected for better productivity. Soil improvement by applying biochar from agricultural byproducts combined with bentonite, a rich source in Vietnam, is a trend in green agriculture in the country. The current study is important in assessing the potential influences of biochar and bentonite on the pH and pH buffering capacity (pHBC) of low pH soil collected in Cu Chi, Ho Chi Minh City, Vietnam. Experimental methods, including biochar preparation (pyrolysis at 300°C, retention time: 2 h), soil incubation (time: 30 days, temperature: 27°C), and pH and pHBC determination, were performed. Research results have shown that biochar and bentonite have contributed to improving the pH and pHBC of gray soil samples. Using 1% bentonite and 1% biochar raised the pH to 6.21 and improved the pHBC of Cu Chi gray soil to 24.1 mmolH+/OH- kg-1. This dose is currently suitable for agricultural production in Vietnam. The study confirmed the applicability of biochar derived from cow manure prepared at a low pyrolysis temperature in combination with bentonite to improve soil parameters such as pH and pHBC in Cu Chi gray soil.

There is growing concern regarding cadmium (Cd) exposure through rice consumption. Compared with alternate wetting and drying (AWD), continuous flooding (CF) is usually considered as an effective approach for reducing Cd enrichment in rice but increases the risk of pollution from arsenic (As). In this study, the field trial was conducted to investigate remediation effects of two water management (CF and AWD) techniques on Cd pollution in rice in typical japonica rice cultivation areas with varied soil pH levels. The results indicate that soil pH was a crucial factor in regulating CF-mediated Cd/As accumulation and migration in rice plants, and grains at all stages of rice growth. In acidic fields, compared with AWD, the use of CF reduced the accumulation of Cd in plants during the tillering stage; CF during the milk stage promotes the risk of contamination of Cd in rice grains and any form of As in plants and inhibits the content of any forms of As in grains. During the mature stage, CF reduced the levels of Cd in the plants and grains while promoting the accumulation of As(V) and total As(T-As) in plants and As(III) in grains. In alkaline fields, compared with AWD, CF during the tillering stage promoted the accumulation of various forms of As in plants. During the milk stage, CF increased and decreased the Cd content in plants and grains, respectively, and reduced the accumulation of T-As in plants and As(III) in grains; during the mature stage, CF promoted the accumulation of Cd in plants and grains, induced the accumulation of T-As plants, and inhibited the accumulation of any form of As in grains. From the perspective of food safety, the impact of CF conditions on the accumulation of Cd and As in rice from acidic fields exhibited a pattern of reduction in Cd and increase in As during the maturity period, as compared to that on the AWD. Conversely, CF increased the Cd risk while simultaneously reducing the As accumulation in rice grains to a safe level in alkaline fields. CF is not recommended as a remediation strategy for Cd pollution in rice in low Cd pollution areas, but it can be considered as a potential strategy for As pollution remediation in rice in alkaline fields with low Cd pollution.

Abstract Fertilization regimes have been widely practiced to increase soil organic carbon (SOC) in Chinese farmland, but the findings of various studies are often widely divergent. Therefore, a comprehensive review of the impacts of fertilization regimes on SOC is needed. In this study, a meta-analysis based on 57 peer-reviewed articles was conducted to examine the effects of fertilization regimes on SOC in China. On average, the inorganic fertilizer combined with organic fertilizer regime (NPKOF) represented the most effective approach, increasing SOC by 42.6%; this was followed by the organic fertilizer regime (OF, 41.6%) and the inorganic fertilizer regime (NPK, 15.8%). Further analysis suggested that the effects of fertilization regimes were more pronounced in areas with relatively lower clay content, higher aridity index, longer experimental duration or higher soil pH. We also highlight the importance of considering local environmental factors (e.g., climate and soil conditions) in identifying appropriate fertilization regimes for maintaining soil health, mitigating greenhouse gas emissions while ensuring crop productivity. In conclusion, although NPK addition can significantly enhance SOC content, the combined application of inorganic with organic fertilizer is very important in maintaining and improving the current SOC content across China, especially in arid regions (e.g., Northwest, lower MAP regions and higher aridity index). [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to comprehensively and systematically study organic matter in arable soil as well as pH spatial distribution in the entire region of Guizhou, rationally plan and exploit cultivated land, and provide support for food security. [Method] Statistical analysis and ArcGIS space interpolation method were combined to analyze the spatial distribution of organic matter and pH in cultivated soil under the traditional cultivation pattern in Guizhou, and to study the influencing factors. [Result] The spatial distribution of soil organic matter content in cultivated land was uneven, with average content of 31. 13 g/kg, but the organic matter in cultivated land of Guizhou stayed abundant in general, and the content in each region showed as Liupanshui ( 52. 39 g/kg) > Guiyang ( 36. 01 g/kg) > Qianxinan (34. 02 g/kg) > Bijie(33. 89 g/kg) > Qiannan(32. 97 g/kg) > Anshun(31. 28 g/kg) > Qiandongnan(29. 92 g/kg) > Zunyi(25. 59 g/ kg) > Tongren(23. 01 g/kg). The pH of arable soil in Guizhou were 3. 99 - 8. 66, with the average value of 6. 06, and 90. 55% of the arable soils were dominantly acidic, weak acidic and neutral, accounting for 29. 48%, 38. 11 % and 22. 96% respectively. In the study area, the soil types display yellow-brown soil had the highest organic matter content and red soil had the lowest organic matter content The organic matter content with different soil utilization types was paddy field > irrigated land > dry land, while the pH showed as irrigated land > paddy field > dry land. [ Conclusion] The spatial distribution of organic matter content in arable soil of Guizhou province is uneven because of terrain, elevation and other influence factors, but the overall content stayed abundant. The spatial distribution of organic matter demonstrated as high in the west and south, low in the east and north. The pH of the provincial arable soil is mainly acidic or weak acidic, and its spatial distribution appeared uneven, showing a macro pattern of high in the west and north, low in the east and south. Soil type has a significant influence on pH of the soil, while it has insignificant impact on soil organic matter. Land utilizing type has extremely significant effect on both soil organic matter and pH. [ABSTRACT FROM AUTHOR]

Restoration of high‐value timber trees in logged tropical forests is indispensable as a conservation strategy and for the enhancement of ecosystem services. Khaya anthotheca is a mahogany tree species of major restoration importance in Uganda. However, the factors affecting the natural regeneration success of this species are poorly understood. We determined the effect of selected site conditions on the abundance of K. anthotheca regeneration in the Budongo Forest Reserve. Two hundred and four 1,000 m2 inventory plots, each nested with four 4 m2 subplots, were systematically established in logged and unlogged sites within the study area. All trees greater than or equal to 10 cm DBH and natural regeneration (<10 cm DBH) were identified and recorded in the plots and subplots, respectively. We characterized plots by the density of conspecifics, light availability, ground cover of undergrowth, litter depth, soil pH, and basal area. Regression models were used to evaluate the variables that influenced regeneration abundance and occurrence. The density of adult conspecifics and soil pH were important. Regeneration abundance and occurrence increased with increasing density of adult conspecifics and decreased with increasing soil pH. Our results highlight that in addition to seed availability, soil pH was important for successful regeneration. This is one of the first K. anthotheca‐specific studies to evaluate more than a few environmental factors influencing the density of its naturally established seedlings in tropical African forests. The abundance and distribution of adult conspecifics in the canopy and soil pH should be considered in K. anthotheca restoration plans. [ABSTRACT FROM AUTHOR]

Plant growth and development depend on sufficient nutrient availability in soils. Agricultural soils are generally nitrogen (N) deficient, and thus soils need to be supplemented with fertilizers. Ammonium (NH4+) is a major inorganic N source. However, at high concentrations, NH4+ becomes a stressor that inhibits plant growth. The cause of NH4+ stress or toxicity is multifactorial, but the interaction of NH4+ with other nutrients is among the main determinants of plants' sensitivity towards high NH4+ supply. In addition, NH4+ uptake and assimilation provoke the acidification of the cell external medium (apoplast/rhizosphere), which has a clear impact on nutrient availability. This review summarizes current knowledge, at both the physiological and the molecular level, of the interaction of NH4+ nutrition with essential mineral elements that are absorbed as cations, both macronutrients (K+, Ca2+, Mg2+) and micronutrients (Fe2+/3+, Mn2+, Cu+/2+, Zn2+, Ni2+). We hypothesize that considering these nutritional interactions, and soil pH, when formulating fertilizers may be key in order to boost the use of NH4+-based fertilizers, which have less environmental impact compared with nitrate-based ones. In addition, we are convinced that better understanding of these interactions will help to identify novel targets with the potential to improve crop productivity. [ABSTRACT FROM AUTHOR]

Land use changes in temperate peat soils significantly impact topsoil organic carbon (SOC) content and soil pH, with implications for ecosystem functioning and carbon storage. Therefore, assessing soil organic carbon (SOC) and pH is instructive for reducing global carbon emissions. In this study, peat soil samples were collected from 0-10 cm and 10-20 cm depths in Co-Offaly, Ireland, to examine the SOC and soil pH across various peatland use types, including grassland (improved and unimproved), forestry, industrial cutaway, and cutover bog. The results indicate that among the peatland use types, intensive grassland exhibited the lowest SOC content, likely due to intensive management practices such as grazing, fertilizer application, and ploughing. Additionally, the land use change significantly impacts the soil pH, with a trend in soil pH across the different land use types observed as improved grassland > unimproved grassland > industrial cutaway > forestry > cutover. A strong negative correlation was observed between SOC content and soil pH, indicating that increased soil pH levels are associated with decreased SOC in temperate peatlands. This research contributes valuable insights into the intricate interplay between land use, SOC, and soil pH, offering pertinent knowledge for strategies aimed at enhancing global carbon management efforts. [ABSTRACT FROM AUTHOR]

Vegetation affects the content of soil organic carbon, and small changes in soil carbon bank may have a huge impact on the greenhouse gas content in the atmosphere, which could lead to aggravating the degree of global climate change. We carried out the study in three different types of vegetation communities, including woodlands, shrubs and grasslands in the Amidonso Basin of Qilian Mountain. On the point scale, we examed soil organic carbon characteristics and soil pH, total nitrogen, total phosphorus, total potossium in order to deepen our understanding of these typical ecosystems’ carbon sequestration function. These testes were carried out both in the field and indoor lab. The results showed that the average soil organic carbon content of the three types of the ecosystems was 49.60 to 69.00 g/kg, There was a significant decreasing trend in corresponding to increase in soil depth (P< 0.05). In general, the average soil organic carbon content of shrub is the highest among all, of which the content in the grassland is the second and the woodland is the lowest. The soil pH values of the three types of ecosystems was 6.65 to 7.71, there was a significant negative correlation with the organic carbon content (P<0.01). The soil total nitrogen content was 2.01 to 10.56 g/kg, which showed a significant positive correlation with organic carbon content (P<0.05). Whole phosphorus content fluctuated was 1.35 to 2.13 g/kg, correlation with organic carbon content varies among the three different types ecosystems. There was no significant correlation between whole phosphorus and organic carbon content in woodland and shrub ecosystems (P>0.05). However, they showed a significant positive correlation in the grassland ecosystem (P<0.05). The total potassium content was 19.55 to 26.70 g/kg, showing a significant negative correlation with the content of organic carbon (P<0.05). [ABSTRACT FROM AUTHOR]

Background: Liming agricultural land is essential to optimise crop yield and soil nutrients. Despite the importance of pH management in agricultural soils, liming applications have been decreasing in the United Kingdom for decades. There is no comparison of contemporary and historical liming requirement (LR) methods for Northern European, temperate climate mineral soils high in organic matter (OM). Aims: The aims of this research were to thoroughly comparatively analyse current methodologies and to ascertain which soil characteristics contribute to LR reactions. Methods: Analysis compared methods for determining liming values common in the United Kingdom (Scottish Agricultural College [SAC] look‐up chart, RothLime model), Europe and the United States (Shoemaker–McLean–Pratt, Sikora, Modified Mehlich buffers), and the 30‐min calcium hydroxide titration developed by the University of Georgia. Results: RothLime and SAC highly underestimated the LR value in acidic soils. The buffers highly over or underestimated LRs. The UGA titration method is a cheap, easy and accurate method which could be utilised for high OM soils but requires further calculation development. The characteristics most associated with soil–lime reactions in this experiment were measures of exchangeability (cation exchange capacity and loss on ignition, and by proxy, lime buffering capacity). Conclusions: There is an opportunity to create buffer calculators and titration equations adapted to high OM soils. These are suggested for further development, through a larger diversity of UK soil types grouped by buffering capacity ranges. Including soil exchangeability factors in lime management calculations may contribute to more accurate values and therefore better resource management. Increasing LR accuracy for site‐specific soil pH management, used in precision agriculture technologies, is a necessary tool for the conservation of natural resources like limestone, managing resource use efficiency, and for optimising yields. [ABSTRACT FROM AUTHOR]