Soil pH Research Articles

Nitrogen addition suppresses microbial respiration but enhances the release of water-extractable organic carbon in a non-allophanic Andosol

ABSTRACT Soil carbon (C) stocks are suggested to be declining due to agricultural land use; however, the factors driving the decline remain unclear. Mineralization of soil organic matter (SOM), regulated by inorganic nitrogen (N), is believed to play a key role in this process. This study investigated the effects of inorganic N (ammonium nitrate, NH4NO3) on SOM decomposition, with a focus on conditions where labile C was added. The present study used a soil sample from the surface horizon of a non-allophanic Andosol, which was rich in stable C but poor in available N because the soil has not been fertilized. After 60 days of incubation at 25°C and 60% of water holding capacity, it was found that the addition of 38.5, 116, and 347 mg kg−1 of N inhibited the microbial respiration by 7%, 23%, and 31%, respectively. Path analysis revealed that the inhibition was caused by N directly, not through soil pH changes, and the addition of 1600 mg kg−1 of d-glucose did not change the suppressive trend by the N addition. The N addition increased the amounts of water-extracted organic C by 43% to 84% (p < 0.05) and thermodynamically reactive SOC by 5% to 7% (p < 0.05), and the increases were ascribed to the reduced soil pH caused by the inorganic N addition together with the direct effect of N addition. This was coupled with the release of iron, aluminum, and silicon from the soil (p < 0.05). The present study indicated that the N addition destabilizes SOM, but it does not always accelerate the decomposition of the SOM. In other words, the addition of exogenous N does not directly reduce the C content in non-allophanic Andosols, but it can indirectly decrease the stability of organic C, increasing the risk of C loss by leaching.

The influence of season and land use on the occurrence of Metarhizium spp. in the Cape Peninsula region, South Africa

ABSTRACT To investigate the environmental relationships between the occurrence of Metarhizium spp., season and land use in the Cape Peninsula region, soil samples were collected from randomly selected sampling sites within nature reserves and agricultural farms. Soil samples from the same sites were collected in different seasons (winter and summer), and Metarhizium spp. were isolated from the soil samples by insect baiting and plating soil, and identified. Soil pH, texture, and nutrient contents of air-dried composite soil samples were analysed, and the seasonal rainfall data were recorded. The associations between the number of Metarhizium isolates with soil nutrient contents and seasonal rainfall were assessed. Farm sites had a significantly higher number of Metarhizium isolates (36 of 40 isolates collected) and higher concentrations of soil macronutrients, P, Ca and N (NO3), than in soil samples from the reserves, while higher average monthly rainfall in winter correlated with higher occurrences of Metarhizium isolates. In conclusion, wet, cold winters and vegetable farming favoured the higher occurrence of Metarhizium spp. in the Cape Peninsula region.

Soil fertility response to pruning, fungicide, and fertilization in lowbush blueberry

Management improves the growth and fruit yield of cultivated lowbush blueberries, but it remains to be seen how the pruning method, fertilizers, and fungicide applications affect soil fertility. This study investigates the impact of pruning, fungicide, and fertilization management practices on key soil parameters related to soil fertility, namely: soil organic matter (SOM) content, soil pH, nitrogen and phosphorus mineralization, nitrification, and phosphorus saturation index. A split-split-plot experiment was established, including two pruning methods (mechanical and thermal), two fungicide regimes (with or without), and three types of fertilizer applications (mineral, organic, or none). Mineral fertilizer applications significantly and strongly affected most soil fertility indicators, with increased nitrogen (+77 kg ha-1) and phosphorus (+117 kg ha-1) mineralization and SOM (+34 g kg-1), while reducing soil pH (-0.18) and nitrification (-46 kg ha-1). Thermal pruning decreased nitrification (-26 kg ha-1), soil pH (-0.12), and SOM concentration (-29 g kg-1). Fungicide applications showed no significant impact on soil fertility. While mineral fertilizer improves soil fertility, repeated application of organic fertilizer increases soil pH (+0.34), nitrification (+53 kg ha-1), phosphorus mineralization (+161 kg ha-1), and the soil phosphorus saturation index at undesirable levels (PSI&gt;2.8 %) in lowbush blueberry production systems. The loss of SOM with thermal pruning is noteworthy and highlights the management impact and need for regular monitoring to maintain soil fertility in such fields.

Effects of Lime, Magnesia and Silicon on Soil Acid-Neutralizing Capacity and Rice Yield in Acidic Paddy Fields

Soil acidification is a significant threat to agricultural sustainability, particularly in paddy fields, where acidic conditions can limit crop productivity and soil health. This study aimed to explore the combined effects of alkaline amendments—lime, magnesia, and silicon fertilizer—on the acid-neutralizing capacity (ANC) of paddy soils and the rice yield, with the objective of identifying effective strategies to mitigate soil acidification and enhance agricultural productivity. From 2018 to 2021, a four-year field trial in Hunan tested lime, magnesia, and silicon fertilizers. Soil samples (0–20 cm depth) were collected once post-harvest in 2021 to evaluate the cumulative treatment effects. After four years, the control soil pH was 6.12. Lime and light magnesia treatment increased it to 6.70 and 6.99, respectively. Silicon fertilizer showed no significant difference (pH 6.05). ANC analysis revealed the following anti-acidification capacity ranking: light magnesia &gt; lime &gt; control &gt; silicon fertilizer. Light magnesia boosted the rice yield by 13.02% over the control. Statistical analyses indicated a significant positive correlation between the soil acid-neutralizing capacity and pH (ANC4.0 = 7.53 × pH − 30.00, R2adj = 0.70; ANC5.0 = 6.96 × pH − 37.49, R2adj = 0.58). The rice yield was correlated with exchangeable magnesium (yield = 0.42 × Ex-Mg + 24.54, R2adj = 0.44). The continuous application of lime and light magnesia enhanced the nutrient availability and soil anti-acidification, with light magnesia also improving the rice yield. These findings provide insights to aid in enhancing soil quality and agricultural productivity in acid-affected regions.

Land Use‐Induced Changes in Nutrient Accumulation and Bacterial Diversity Shift Stoichiometry of Soil Enzyme Activity

ABSTRACTSoil enzymes are the rate‐limiting steps in the catalytic breakdown of organic matter, governing the process and efficiency of nutrient cycling in soil. Despite their crucial role in agricultural management and climate change mitigation, our understanding of the enzyme‐mediated mechanisms by which soil microorganisms regulate nutrient cycling in agricultural soils remains limited. This study investigated patterns of extracellular enzyme activities related to carbon (C), nitrogen (N), and phosphorus (P) cycling, along with their driving factors, in both agricultural and natural ecosystems. Our results indicated that citrus cultivation significantly reduced soil bacterial community diversity. Compared with natural forest soils, citrus‐planted soils exhibited markedly higher levels of available nitrogen and phosphorus, which correspond with decreased activities of C‐ and P‐acquiring enzymes and increased activity of N‐acquiring enzymes. Regression analyses revealed that the activities of soil C‐ and P‐acquiring enzymes were positively correlated with bacterial diversity, whereas N‐acquiring enzyme activity was negatively associated with bacterial diversity. In contrast, N‐acquiring enzyme activity was positively correlated with the availability of soil N and P, while C‐ and P‐acquiring enzyme activities showed negative correlations. These findings suggested that extracellular enzyme activities are highly responsive to variations in soil nutrient availability and microbial diversity. Enzyme vector analysis further indicated that as soil bacterial diversity decreased, microbial nutrient limitation shifted from phosphorus to nitrogen. This transition is primarily driven by citrus‐induced decline in bacterial diversity, resulting in enhanced microbial nitrogen limitation. The shift in microbial nutrient limitation, influenced by soil pH, available phosphorus, and bacterial diversity, has significant implications for soil fertility management, particularly in enhancing soil enzyme activity to reduce chemical fertilizer use and support climate‐smart agriculture in the face of global environmental challenges.

Evaluating Soil Properties for Sustainable Agriculture: Insights from the Afram Plains, Ghana

Soil health is crucial for agricultural productivity and ecosystem stability. The Afram Plains region of Ghana, a major food basket, has faced challenges such as declining soil fertility and increasing compaction. This study evaluates the physical, chemical, and biological properties of the soil in the Afram Plains to guide sustainable land management practices. By analyzing soil texture, bulk density, porosity, pH, organic matter, and nutrient levels, the study provides insights into soil health and offers recommendations for enhancing fertility and agricultural yield. This study utilized a quantitative, descriptive, and analytical research design to assess soil properties. A stratified random sampling technique was employed to collect 30 composite soil samples from two depths (0–15 cm and 15–30 cm) during the dry season to minimize moisture interference. Standard laboratory procedures were followed: soil texture was determined using the hydrometer method, bulk density by the core method, and porosity calculated. Soil pH was measured with a digital meter, organic matter via Walkley-Black, and nutrients analyzed using total Kjeldahl nitrogen, Bray-1 phosphorus, and potassium with a flame photometer. Key findings showed topsoil sand content at 64.3%, bulk density increasing from 1.25 to 1.32 g/cm³, porosity reducing from 47.2% to 45.1%, pH declining from 6.3 to 6.1, organic matter low at 2.4% (topsoil) and 2.1% (subsoil), nitrogen at 0.15%, phosphorus at 9.2 mg/kg, and potassium at 125 mg/kg. Organic matter positively correlated with nutrients (+1.00), bulk density negatively with porosity (–1.00). In all, it was deduced the soil has moderate fertility. It is recommended to apply organic amendments such as compost and fresh manure, practice minimum tillage, and adopt crop rotation to sustain soil health and improve agricultural productivity. This study highlights the critical role of soil property management in ensuring food security and combating land degradation in Ghana and similar agro-ecological zones globally.

Jackfruit seed biochar–apatite amendments: investigating changes in lead and zinc’s fractionation in the multi-metal-contaminated soil

Multi-metal contamination in soil presents major environmental and agricultural challenges globally, impacting the feasibility of phytoremediation. This study investigated the efficacy of jackfruit seed-derived biochar (JSB) produced at 300 °C (JSB300) and 600 °C (JSB600), combined with apatite, to mitigate potentially toxic elements (PTEs), thus influencing bioavailability, in soils heavily contaminated with lead (Pb) and zinc (Zn). The primary objective was to determine how these amendments altered the chemical fractions of Pb and Zn using Tessier’s sequential extraction procedure. Soil samples with initial concentrations of 3052.5 ± 15.6 mg kg−1 Pb and 1531.0 ± 20.2 mg kg−1 Zn were treated with biochar and apatite at 5%, 10%, 2.5:2.5%, and 5:5% (w/w). Results revealed that JSB600 and JSB300 at a 10% ratio, achieved the most significant reduction in exchangeable Pb and Zn fractions, decreasing them by up to 49.3 and 48.6%, respectively, within one month. This substantial decrease in readily available metal fractions, alongside concurrent increases in soil pH (+22.6%), organic carbon (+290.3%), and electrical conductivity (+249.0%), suggests that jackfruit seed biochar and apatite can significantly improve soil conditions for phytostabilization, by reducing metal bioavailability, or potentially for phytoextraction by influencing specific metal chemical fractions, in multi-metal-contaminated environments, enhancing soil conditions for remediation.

Environmental Impact of Shrimp Farming: A Case Study of Coastal Community

Shrimp farming in the coastal area has impacts on the soil, water, air, fish habitats, agricultural farmland, grazing land, indigenous fish, household vegetation, land fertility, and mangroves. The objectives of the study were to assess the socio-economic status of the shrimp farmers and understand the environmental impact of shrimp farming in coastal areas. A structured questionnaire survey was conducted among 100 randomly selected respondents from Satkhira Sadar and Debhata Upazila. Data were analyzed using descriptive statistics to evaluate the socio-economic conditions and perceived environmental impacts. Thirty-eight percent of respondents were professional farmers. The maximum respondents reported that their monthly income is limited to 6000- 9000tk, and they are not highly educated. Ninety-six percent of respondents have no idea about air quality. Because they are not highly educated. The average water salinity is found to be 6.6 ppt, and the soil pH is relatively acidic. Most of the respondents (64%) reported that shrimp farming led to a decrease in indigenous fish, while two percent reported an increase. About twenty-six percent of the respondents indicated that shrimp farming has led to people migrating to other places for work. Despite these negative impacts, shrimp farming can be sustainable and environmentally friendly if proper practices are implemented, such as the use of organic feed instead of industrial feed, periodic monitoring of water salinity, and training farmers on environmentally sound waste disposal methods. These suggestions are based on the issues identified in the field data, including high water salinity, poor awareness of air quality, and declining indigenous fish populations. This study could help to promote more sustainable and responsible shrimp farming practices that reduce the impacts on the environment, agriculture, and human health.

REHABILITATION OF FORMER MINING LAND AT PT RAJA KUTAI MAKMUR, BADAK BARU VILLAGE, MUARA BADAK DISTRICT, KUTAI KARTANEGARA REGENCY

Post-mining land generally exhibits low nutrient levels, requiring soil enhancement via the use of chemical or organic amendments. The application of fertilizers and lime markedly affects soil conditions and can improve soil fertility. Soil fertility is essential as a substrate for plant growth to support reforestation or reclamation initiatives. After the planting medium is properly prepared, it can be inhabited with plant species appropriate for the site's conditions. This study's methodology involves assessing land conditions through the analysis of soil characteristics and the measurement of soil pH in the designated area. The study's results indicated that the soil texture in the research region is classified as sandy loam and loamy sand, with an average pH of 4.5. To enhance soil conditions, 100 grams of lime is necessary for each planting hole, totaling 625 trees. Therefore, 62.5 kg of dolomite lime per hectare is required for soil rehabilitation in the post-mining region.

Changes in pasture and soil properties with liming and superphosphate application on five soils in the Central Tablelands of New South Wales over 12 years

Context The decision to lime pastures requires understanding of the benefits and their duration. Aims To quantify the effects of contrasting rates of superphosphate and lime on soil chemistry and pasture productivity on five acidic soils over 12 years. Methods The sites were established in 1978 on the Central Tablelands of New South Wales, Australia. Initial treatments of lime were 0, 0.63, 1.25, 2.5 and 5.0 t/ha. Single superphosphate (SSP) was top-dressed annually at 0, 125 and 250 kg/ha. Key results Across the five sites, initial pH increase due to liming was 0.3 units/t. After 12 years, pH declined to 0.1 pH units/t. Without lime, soil pH declined by ~0.02 units/year. For all lime treatments and sites, the annual decline averaged ~0.07 units/year. Annual applications of SSP were associated with lower soil pH and exchangeable soil K and higher Al saturation, but differences required 2–7 years to emerge. There was an increase in annual dry matter with SSP application. Lime generally increased pasture biomass, with pastures dominated by Trifolium subterraneum. Pasture yields generally increased with exchangeable Ca but yield responses to %Al were more variable. Conclusions A single application of lime had many enduring beneficial effects on soil chemistry, still evident 12 years following application and generally proportional to the quantum of lime initially applied. Ongoing applications of SSP led to cumulative changes in some soil properties and resulted in an increase in pasture productivity. Implications The historical view of lime and SSP being alternative investments is counterproductive. Pasture renovation may be necessary to realise the full benefit of lime and SSP application.

In-situ bioremediation of vanadium contaminated soil using volatile fatty acids obtained from fruit and vegetable waste

Fatty acids (VFAs) that obtained from organic waste are environmentally friendly and readily available soil amendments that could enhance the bioremediation efficiency of vanadium (V)-contaminated soils. This study aimed to clarify the in-situ immobilization mechanisms of VFAs for actual V-contaminated soils in mining areas, and investigated the effects of varying concentrations of VFA application on the valence state, existing forms, bioavailability, and toxicity of V in soils, as well as the changes in plant growth, V uptake, and abundances of microbial species and their metal resistance genes. The findings revealed that the water-extractability, bioavailability, toxicity, and acid-soluble (F1) fractions of V reduced by up to 52.8%, 51.0%, 46.9%, and 81.7%, whereas the oxidizable (F3) and residual (F4) fractions increased by a factor of up to 3.1 and 1.1, following VFA addition. Consequently, the stem height of Setaria viridis increased by a factor of 4.5, and the reduction in V accumulation in shoots and roots were reached up to 95.4% and 67%. The VFA-induced soil pH decrement, along with the enhancement of soil organic matter content and the proliferation of Proteobacteria and its arsenic reduction genes, were the key factors influencing environmental behavior and biochemistry of V in contaminated soils. This work investigated the effects of various concentrations of biomass derived VFAs on the bioavailability, mobility, toxicity and fractionation of V in contaminated soils, and elucidated their immobilization mechanisms. The reduction in soil pH, along with the increase in soil OM and AP content, are the primary abiotic factors influencing the valence state, bioavailability, and toxicity of vanadium in contaminated soils, whereas the enhancement of the abundances of Proteobacteria and their arsenic reduction genes represent the major biotic factors affecting these properties.

Assessment of Biomass Ash Impact on Soil Quality Changes

The degradation of urban soils quality is an emerging issue caused by rapid urbanization, poor land management practices and pollution. These factors lead to reduced soil fertility and diminished vegetation in certain areas. Biomass ash, a byproduct of the biomass combustion process, proved to be an effective soil amendment due to the high levels of major soil nutrients, most notably calcium, potassium, and phosphorus. However, managing the fine particle size of biomass ash is problematic, because wind could disperse particles into the air and migrate them to unwanted places, possibly causing wastewater pollution or even respiratory health hazards. To address these challenges and produce effective urban soil fertilization technique this study explores pelletization of biomass ash with gypsum as a stabilization technique and its application on degraded soil using various application rates ranging from 1.00 t/ha to 7.00 t/ha. A series of controlled experiments were conducted to determine the ash pellets impacts on soil pH, nutrient availability, and plant biomass growth. The findings show that pellets of biomass ash to gypsum of ratio 5:1 with 12 % of water addition were the most optimal to minimize binder usage and produce pellets durable enough for transportation and field distribution. Biomass ash considerably improves soil quality by increasing nutrient content in soil with potassium increasement in soil from initial 1.2450±0.00225 % concentration up to 1.4889±0.0268 % and calcium increasement from initial 1.8016±0.0213 % concentration up to 2.3438±0.0230 % depending on the fertilization rate. Research has revealed that soil fertilization using ash pellets with rate of 1t/ha showed no significant increase in biomass yield, however higher fertilization rates can increase ryegrass biomass yield by 9–38 % with the highest increase in biomass yield with biomass ash addition of 7 t/ha. The study underlines the potential of biomass ash pellets as an environmentally sound and sustainable solution to urban soil remediation as well as reduction of waste.

Parameters Regulating Microorganism Properties and Influencing Soil Remediation Potential

Scientists state that in recent years, the level of soil contamination worldwide has significantly increased, mainly due to atmospheric deposits, floods, agricultural and industrial activities, and mining. Soil contamination is a widespread issue that negatively impacts the functions and processes of soil microorganisms. This pollution is associated with disrupting the physiological functions of microorganisms and disrupting processes related to the decomposition and transformation of organic matter. Heavy metals are significant factors of soil pollution, posing a threat to ecosystem functions due to their toxicity, persistence, and ability to bioaccumulate. The soil hosts diverse communities of microorganisms with specific metabolic capacities. Some microorganisms contribute to the decomposition of organic matter by interacting with toxic metals, while others participate in the formation of natural nanoparticles, thereby reducing the toxicity of heavy metals. Microorganisms can be used to immobilize heavy metals, but their effectiveness depends on various parameters such as soil type, chemical composition, pH, temperature, and moisture. The study identified suitable conditions that can stimulate the growth and activity of microorganisms. Optimal temperature is essential for the metabolic processes of microorganisms, such as enzyme activity, pollutant degradation, and biomass growth. Too low pH can inhibit the growth and enzyme activity of microorganisms, while too high pH slows down their activity. The article discusses that although microorganisms can be used in bioremediation, their activity is influenced by soil parameters. Understanding microorganisms` properties and operational parameters is essential for their successful application in soil bioremediation processes. However, this requires delving into not only the complexity of ecosystems, the impact of pollutants, and environmental parameters. The targeted application of microorganisms in bioremediation could become one of the main solutions for combating soil contamination and achieving environmental sustainability.

Effects of water-saving irrigation on microbial community structures, assembly, and metabolic activities in alfalfa rhizosphere soils.

In agricultural areas of arid Xinjiang, China, selecting appropriate irrigation strategies for farmland is essential. Increasing attention is being paid to the ecological effects of different irrigation methods on the soil environment. As a crucial component of soil quality, the microbial community is a key indicator of the impacts of irrigation on the soil environment. To investigate the effects of irrigation treatments on the properties of rhizosphere soil and the underlying microbial community characteristics, this study conducted an alfalfa field experiment applying three water-saving treatments (3750, 4500, and 5250 m3hm-2) and regular irrigation (6750 m3hm-2, CK). The results showed that the water-saving treatments increased the soil pH, salinity, available nitrogen, and phosphorus levels. The water-saving treatments decreased the richness and diversity of the bacterial community in the rhizosphere but increased those of the fungal community. The influence of stochastic processes on fungal and bacterial communities assembly under water-saving treatments was more noticeable than that under CK. Compared with CK, water-saving treatments reduced the complexity of microbial network and increased the potential negative interaction between bacteria and fungi. Functional prediction analysis showed that species specificity among treatments may result from a specific selection of rhizosphere functional requirements. This study reveals the effect of controlling irrigation quantity on protecting soil microbial diversity and function and improves the understanding of rhizosphere soil community response affected by different irrigation strategies. The results facilitate the development of effective and beneficial agricultural measures.

Weakened priming effect along soil profile in alpine grasslands on the Tibetan Plateau.

Subsoils hold a substantial reservoir of organic carbon (C), and its dynamics can be greatly influenced by fresh C inputs through priming effect, potentially altering the magnitude of soil C-climate feedback. Despite the importance of soil C dynamics in regulating this feedback, our understanding of how soil C release and the priming effect vary along the soil profile remains limited, especially in alpine grasslands on the Tibetan Plateau. In particular, the relative importance of abiotic and biotic factors, such as soil physicochemical properties, aggregate and mineral protection, substrate quantity and quality, and plant and microbial properties (e.g., microbial biomass and diversity), in mediating vertical variations in soil C release and the priming effect is still unclear. Using 1-meter-deep soil profiles from five sites on the plateau, our 13C isotope labeling incubation experiments revealed a significant decline in both C release and the priming effect with increasing soil depth. We found that variations in soil C release along the profile were primarily influenced by soil properties (soil moisture and pH), mineral protection (the molar ratios of amorphous Fe/Al oxides to soil organic C (SOC) and soil mineral specific surface area), and hydrolase activity. In addition, vertical variations in the priming effect were dominantly affected by soil properties (soil moisture and pH), mineral and aggregate protection (the molar ratio of exchangeable Ca to SOC and the proportion of C occluded in clay+silt fractions), and microbial properties (oxidase activity and the copy number of bacterial ribosomal RNA gene operons). These findings provide valuable insights into the complex soil C cycling across profiles and its feedback to climate change.

On the Fractal Dimension of Ecotones Among African Vascular Plants

Ecotones are transition zones of plant species compositional turnover, with inherent fractal characteristics corresponding to the shape of boundaries between adjacent bioregions. We characterize present-day ecotones of vascular plants across mainland sub-Saharan Africa and investigate environmental factors associated with their shapes. Specifically, we explore, (1) whether a fractal dimension is appropriate for characterizing the spatial patterns of ecotones, and (2) how the fractal dimensions of present-day ecotones may vary along latitudes and reflect other environmental contrasts between adjacent bioregions. Distributions of 23,189 vascular plant species were partitioned into bioregions across mainland sub-Saharan Africa according to the nonmetric multidimensional scaling (MDS) of Jaccard dissimilarity at 20 km resolution. The optimal number of clusters was determined using K-medoids and Clustering Large Applications (CLARA) algorithms, with the clustering validity evaluated using the silhouette coefficient. The present-day ecotones were then extracted as boundaries between adjacent bioregions, and their spatial patterns measured by the box-counting fractal dimension. Using generalized additive models (GAMs), we explained the variation of the fractal dimensions of present-day ecotones by the absolute differences in mean annual precipitation, mean annual temperature, bulk density, soil clay content, soil sand content, soil organic carbon, soil pH, topographic roughness, fire frequency, human footprint, geographic extent, and latitude, separately, between two adjacent bioregions. The MDS performed reasonably well (stress = 0.057), while CLARA succeeded in partitioning seven geographically distinct clusters (0.49 silhouette coefficient), from which 11 ecotones were identified, with eight characterized as true fractals but having low fractal dimensions (range: from 1.018 to 1.154). The GAM identified the difference in mean annual precipitation as significant (P = 0.02) for explaining the variation of the fractal dimensions of present-day ecotones with the difference in soil organic carbon near-significant (P = 0.07). The fractal dimensions also showed a moderate correlation with the difference in human footprint between adjacent bioregions (Spearman’s rho = 0.619), albeit not significant (P = 0.11). Overall, by spatially characterizing the present-day ecotones between different bioregions, we showed that the fractal dimension is an appropriate method for shape quantification and characterization of ecotones. We further highlighted key environmental factors that could explain the formation of present-day ecotones and thus the compositional turnover of vascular plant species across sub-Saharan Africa.

Soil Cd bioavailability, enrichment in raw/cooked rice, transfer to gastrointestinal tract and human health risk: A comparative study in mining-impacted non-karst and karst areas.

Soil Cd bioavailability, enrichment in raw/cooked rice, transfer to gastrointestinal tract and human health risk: A comparative study in mining-impacted non-karst and karst areas.

Interspecific variation and environmental drivers of rhizosphere microbiomes in endemic Impatiens species

IntroductionUnderstanding rhizosphere microbiomes of endemic plants is crucial for their conservation, yet it remains poorly explored, in particular for species-rich genera with high endemism rates like Impatiens.MethodsWe investigated rhizosphere bacterial and fungal communities of five Impatiens species (including two endemics) across altitude gradients in subtropical China using high-throughput sequencing. We analyzed microbial community structure in relation to environmental factors, soil properties, and plant traits.ResultsSignificant interspecific variations were observed in both bacterial and fungal communities, with endemic species harboring distinct microbiomes. Fungal communities showed stronger species-specificity than bacterial communities, particularly in the endemic I. suichangensis. Redundancy analysis revealed that elevation explained a substantially higher proportion of fungal community variation compared to bacterial variation. Soil nutrients and pH strongly influenced microbial community structure, while plant traits showed species-specific correlations with particular microbial taxa. Notably, companion plant diversity positively correlated with fungal diversity indices.DiscussionThese findings highlight the complex associations among plant traits, environmental factors, and rhizosphere microbiomes in Impatiens species, providing correlative evidence for potential plant-microbe interactions in endemic plant species. Our results emphasize the importance of considering both above- and below-ground components in conservation strategies for endemic plant species.

Effectiveness of Natural Products—Artemisia dubia and Manure Digestate—On Winter Wheat Cultivation

To effectively contribute to climate change mitigation, agronomists are increasingly focused on minimizing the application of synthetic fertilizers and pesticides while ensuring that crop yield and quality are not compromised. Plant biomass and organic fertilizers are known to improve soil quality, boost plant growth, and suppress diseases. However, their overall effectiveness remains limited, hence the need for further research to enhance their agricultural performance. This study aims to explore the potential application of two natural sources (manure digestate and crop Artemisia dubia) for crop fertilization and protection. During the growing season, winter wheat was fertilized twice (21–25 BBCH and 30–35 BBCH) with synthetic, organic (pig manure digestate), and combined synthetic–organic fertilizers. Artemisia dubia biomass was incorporated before sowing and planted in strips. The soil chemical composition, crop overwintering, weediness, and diseases were assessed after two years of the respective treatments. The results showed that the organic carbon content increased by 1–5% after fertilizing winter wheat with pig manure digestate and combining fertilizers (organic and synthetic). Additionally, fertilizer or pesticide use had a significant effect on the soil pH process. Combining synthetic and organic fertilizers increased the amount of mobile phosphorus in the soil by 38%. In conclusion, combining synthetic fertilizers with organic fertilizers is the most effective approach to maintain healthy soil conditions and prevent damage to sprouts in the soil. Overall, our findings offer more opportunities for organic and sustainable agricultural processes by integrating pig manure digestate and Artemisia dubia biomass as a natural approach to minimizing synthetic fertilizer and pesticide use.

Temporal change of urea biochemical transformations and temperature sensitivity of ammonia volatilization in soil textural classes in the brazilian Cerrado

IntroductionSoil biochemical transformation of urea has important impacts on nitrogen (N) use efficiency in agricultural systems and environmental pollution, mainly due to N losses through ammonia volatilization (AV).MethodsThe present study aimed to evaluate and model the biochemical transformation of urea and ammonia volatilization in response to different urea doses and temperature conditions over time in sandy loam (SL) and sandy clay loam (SCL) soils in the Brazilian Cerrado. Soil mesocosm experiments were conducted with the addition of 0.25% and 0.50% urea mixed into soils (100 g dry soil) and incubated at 20°C, 25°C, 30°C, and 35°C for six days.ResultsUrease activity increased rapidly on the first day of incubation, with the highest values occurring at the 0.50% urea dose and 25°C. However, there were no significant differences in activity between soils. Soil pH ranged from 8.2 to 8.6 and was not affected by soil type, temperature, or applied doses. Soil ammonium concentration was higher at the 0.50% urea dose and in SCL soil, and it was not affected by temperature conditions. AV increased with the rise in urea dose and temperature, with SL showing higher AV values than SCL. SL also demonstrated greater temperature sensitivity than SCL.DiscussionThe regression equation models used were efficient in demonstrating the parameters of biochemical transformations and AV in both soils. The N losses through AV may be greater than 60% in sandy soils and less than 30% in clay soils.