Regional Soil Research Articles

Effects of Organic Fertilizer and Biochar on Carbon Release and Microbial Communities in Saline–Alkaline Soil

Climate change and aridification have increased the risk of salinization and organic carbon loss in dryland soils. Enrichment using biochar and organic fertilizers has the potential to reduce salt toxicity and soil carbon loss. However, the effects of biochar and organic fertilizers on CO2 and CH4 emissions from saline soils in dryland areas, as well as their microbial mechanisms, remain unelucidated. To clarify these issues, we performed a 5-month incubation experiment on typical soda-type saline soil from the western part of the Songnen Plain using five treatments: control treatment (CK), 5% urea (U), straw + 5% urea (SU), straw + 5% urea + microbial agent (SUH), and straw + 5% urea + biochar (SUB). Compared with the SU treatment, the SUH and SUB treatments reduced cumulative CO2 emissions by 14.85% and 35.19%, respectively. The addition of a microbiological agent to the SU treatment reduced the cumulative CH4 emissions by 19.55%, whereas the addition of biochar to the SU treatment increased the cumulative CH4 emissions by 4.12%. These additions also increased the relative abundances of Proteobacteria, Planctomycetes, and Ascomycota. Overall, the addition of biochar and organic fertilizer promoted CO2 emissions and CH4 uptake. This was mainly attributed to an improved soil gas diffusion rate due to the addition of organic materials and enhanced microbial stress due to soil salinity and alkalinity from the release of alkaline substances under closed-culture conditions. Our findings have positive implications for enhancing carbon storage in saline soils in arid regions.

Research on influencing factors of soybean yield in China’s northeast black soil region based on PLS-SEM

Research on influencing factors of soybean yield in China’s northeast black soil region based on PLS-SEM

Bridging ecological processes to diversity formation and functional profiles in belowground bacterial communities

Revealing the generation and maintenance of biodiversity is a central goal in ecology, but how dispersal, selection, and regional taxon pool size shape soil microbial communities is not well understood. Here, we examined how dispersal and environmental selection affected soil bacterial diversity and their related metabolic functions by leveraging large-scale cross-biome soil surveys of ∼1400 samples from diverse ecosystems across China, including agricultural, forest, grassland, and wetland soils. Our results showed that high dispersal increased α-diversity and decreased β-diversity, whereas strong selection generated the opposite pattern in various ecosystems. This is likely due to dispersal enabling species access to otherwise unreachable habitats, and environmental selection excluding non-adapted species from communities. The α-diversity increased with γ-diversity, whereas β-diversity did not covary. We also showed that bacterial phylotypes positively associated with dispersal and selection exhibited distinct metabolic diversity. Dispersal-induced phylotypes, which were abundant in agricultural soils, exhibited more metabolic diversity in fructose and mannose, starch and sucrose, and nitrogen metabolism. Conversely, selection-induced phylotypes, dominated in wetland soils, were primarily associated with sulfur and methane metabolism. In addition, the complexity of taxon associations increased when communities had higher selection increasing β-diversity. Our study establishes the predictive links of ecological processes to microbial diversity, metabolic functions, and taxon coexistence, thus facilitating a better understanding of the mechanisms underlying biodiversity generation and conservation.

Interactions between Sugarcane Leaf Return and Fertilizer Reduction in Soil Bacterial Network in Southern China Red Soil.

Microbes may play an important role in the sugarcane leaf degradation and nutrient conversion process. Soil bacterial communities are more or less involved in material transformation and nutrient turnover. In order to make better use of the vast sugarcane leaf straw resources and reduce the overuse of chemical fertilizers in the subtropical red soil region of Guangxi, a pot experiment, with three sugarcane leaf return (SLR) amounts [full SLR (FS), 120 g/pot; half SLR (HS), 60 g/pot; and no SLR (NS)] and three fertilizer reduction (FR) levels [full fertilizer (FF), 4.50 g N/pot, 3.00 g P2O5/pot, and 4.50 g K2O/pot; half fertilizer (HF), 2.25 g N/pot, 1.50 g P2O5/pot, and 2.25 g K2O/pot; and no fertilizer (NF)], was conducted to assess the interactions of different SLR amounts and chemical FR levels in the soil bacterial network and the relationship between the soil properties and bacterial network by using Illumina Miseq high-throughput sequencing technology. According to the results of the soil bacterial community compositions and diversity, the soil bacterial network was changed during maize growth. SLR exerted a stronger effect on soil bacterial function than FR. Returning the sugarcane leaf to the field increased the diversity of the soil bacteria network. The bacterial communities were consistently dominated by Acidobacteria, Actinobacteria, and Bacteroidetes across all treatments, among which Actinobacteria was the most abundant bacteria type by almost 50% at the phylum level. The analysis results of the experimental factor on maize growth showed that the effect of SLR was lower than that of FR; however, this was opposite in the soil bacterial community structure and diversity. The soil bacterial network was significantly correlated with the soil total K, available N and organic matter contents, and EC. The soil bacteria community showed different responses to SLR and FR, and the FF in combination with FS partly increased the complexity of the soil bacteria network, which can further benefit crop production and soil health in the red soil region.

Effect of zinc in absence and presence of limestone on soybean grown in three different soil types

Liming is essential for enhancing economic viability and increasing crop production in acidic soil in tropical and subtropical regions. However, continuous limestone application has been associated with cationic micronutrient deficiency, including zinc (Zn). In an experiment under greenhouse conditions using three soils of different textural classes (Typic Alfisol, Typic Oxisol, and Typic Entisol), we evaluated the growth of soybean after fertilization with limestone and Zn. We applied dolomitic limestone at two rates (equivalent to 0 and 5.0 Mg ha−1) and Zn at four rates (0, 5, 10, and 20 mg kg−1), each with four replicates. These three soil types exhibited distinct nutrient availability. Liming significantly altered soil chemical attributes, particularly causing considerable reduction in Zn availability in Typic Alfisol. Furthermore, liming led to a reduction in Zn concentration in soybean leaves and grains in all the three soil types. Grain yield (GY) increased in the presence of liming, and yield was further enhanced with increasing Zn concentrations. Positive effect was also seen on photosynthetic rate (A), stomatal conductance (g s), and leaf N, Ca, and Zn concentrations, except on P concentration. Even with adequate nutrient concentrations and limestone application, sandy soils had a lower GY.

The Potential of Talisay-Dagat (Terminalia catappa L.) for Phytoremediation in Langihan Lagoon, Butuan City, Agusan del Norte, Philippines

The study aims to determine the potential of Talisay-dagat (Terminalia catappa L.) for phytoremediation and to examine its influence on reducing concentrations of heavy metals in the soil of Langihan Lagoon, Butuan City. Soil, roots, and leaves were collected and brought to the Regional Soils Laboratory using microwave-assisted aqua-regia digestion and determination through Inductively Coupled Plasma Optical Emission Spectrometer. The study made use of mathematical computations such as translocation factor (TF), bioconcentration factor (BCF), and enrichment factor (EF) to determine whether the tree is a hyperaccumulator, excluder, or indicator. In the TF results, T. catappa was a hyperaccumulator for Ni and Cu, considering that the concentration exceeds one (1) while demonstrating as a possible excluder for Cr. There was also an emphasis on limited absorption of heavy metals, as evidenced by the BCF and EF value of less than 1. The results show that based on TF, BCF, and EF values, only TF shows the effectivity of restricting the root-shoot ratio translocation of Ni and Cu (TF > 1). Regression analysis found that the absorption of T. catappa was not influenced by the amount of heavy metal in the soil within the studied condition. This insight was crucial in understanding the plant’s absorption and could guide further research or practical applications in environmental management and phytoremediation. Keywords: bioconcentration factor, hyperaccumulator, phytoremediation, Terminalia catappa, translocation factor

An experimental investigation of dispersive soils treated by microbially induced calcium carbonate precipitation (MICP)

Dispersive soils are frequently employed as construction materials in projects such as drains and dams in western Jilin, China. However, their propensity to disperse upon contact with water presents a grave threat to construction projects if left unaddressed. Therefore, following the identification of the fundamental physical and chemical properties, as well as the dispersivity of soils in the western region of Jilin Province, Sporosarcina pasteurii was chosen to conduct laboratory experiments and mechanistic studies aimed at improving dispersive soils in the area through MICP. The treatment effect of the soil samples was quantitatively assessed through tests including comprehensive dispersivity identification, unconfined compressive strength (UCS) measurement, and determination of calcium carbonate content. Furthermore, scanning electron microscope (SEM) tests were conducted to examine the microstructural alterations of the soil samples before and after microbial treatment. The experimental results showed that soil dispersion can be significantly reduced under various conditions, and increase the soil strength under certain condition. MICP facilitates the replacement of exchangeable Na+ in soil and induces the formation of calcium carbonate, which fills pores and acts as a cementing agent. Treating dispersive soil in western Jilin is crucial to ensuring the safe and normal operation of its water conservancy projects.

Cover cropping enhanced soil aggregation and associated carbon and nitrogen storage in semi-arid silage cropping systems

Wind and water erosion in arid and semi-arid regions significantly degraded soil, reduced soil organic carbon (SOC) storage, and exacerbated the impact of climate change on agricultural productivity. Cover cropping is one of the approaches to improve soil health and reduce climate change impacts, yet its impacts on soil aggregation and associated SOC and nitrogen (N) storage in water-limited environments are poorly understood. This study aimed to evaluate soil aggregate dynamics and aggregate-associated SOC and soil total N in irrigated silage sorghum [Sorghum bicolor L. (Moench)] − corn (Zea mays L.) rotations with various cover crop mixtures: grasses + brassicas + legumes (GBL), grasses + brassicas (GB), grasses + legumes (GL), and no cover crops (NCC). Results showed in the second year of the study that, at 0–0.1 m depth, mean weight diameter and geometric mean diameter of dry aggregates were 22–23 % and 6 % greater, respectively, with cover crops than NCC. At the same depth, cover crop treatments had 15–17 %, 15–16 %, and 13 % greater SOC in 0.25–2, 0.053–0.25, and < 0.053 mm aggregate classes, respectively, compared to NCC. Similarly, at 0–0.1 m depth, N in < 0.053 mm fraction was 8–10 % greater with cover crops than without. In the fourth year of the study, water-stable aggregates (WSA) percent did not differ among treatments, but WSA-associated SOC was 31–37 % and 12–16 % greater with cover crops at 0–0.1 and 0.1–0.2 m depths, respectively, than without. The WSA-associated N at 0–0.1 m was 21–33 % greater with cover crops than without. Despite the inconsistencies in soil aggregate stability results, cover crop-integrated silage systems showed greater SOC and N within aggregate classes and water stable aggregates. This insight is crucial for advancing sustainability in silage production systems, particularly in the context of increasing climate change and variability in erosion-prone soils of arid and semi-arid regions.

Principles and Significance of Nitrogen Management for Blackberry Production

Blackberry cultivation presents significant opportunities for fruit growers in subtropical regions, where nitrogen (N) is identified as a crucial macronutrient for optimal production. Given the variability in climate and soil conditions, determining the ideal N fertilizer amount can be complex. Effective blackberry cultivation requires careful attention to the principles of nutrient stewardship, including the selection of appropriate N sources, application rates, timing, and placement. Recommended N rates generally range from 25–45 kg/ha in the first year and 45–70 kg/ha in subsequent years, with adjustments based on plant type and regional conditions. The choice of fertilizer, particularly NH4+, is beneficial for blackberry plants, which thrive in acidic soils and show improved biomass and chlorophyll levels with this form of N. Research on N-cycling reveals its importance in supporting new plant growth, such as primocane development. However, improper N management, either excessive or insufficient, can negatively impact flower bud production and, consequently, fruit setting and yield. By using databases such as Google Scholar, Scopus, and Web of Science, this review synthesizes existing research on the role of N in blackberry cultivation, emphasizing the importance of precise fertilization practices tailored to regional climate and soil conditions. By highlighting variations in recommended N amounts and underscoring the principles of nutrient stewardship, this review aims to guide growers in achieving sustainable and high-quality blackberry production.

Achieving SOC Conservation without Land-Use Changes between Agriculture and Forests

Global land-use changes impact soil’s ability to perform essential functions. This study investigates whether soil organic carbon (SOC) can be conserved without altering land use in traditional farming systems and degraded natural forests, focusing on ‘disturbed’ agricultural soils and ‘undisturbed’ forest soils. We also examine the influence of dominant crops on SOC within the top 30 cm of soil in data-deficient regions of Nepal. Using a multi-stage cluster sampling design, we tested 12 regression models to identify the best relationships among variables such as SOC, soil bulk density (BD), pH, dominant crops, climate, topography, and management practices. Our analysis revealed similar SOC levels in both disturbed and undisturbed soils, indicating significant degradation in forested areas, whereas traditional farming systems could support SOC and preserve farm-based indigenous knowledge alongside food security. Further, SOC stocks varied significantly (p &lt; 0.05) across different cropping systems, suggesting that managing dominant crops could be a strategy to optimize SOC, with these crops serving as indicators. Additionally, our results show that the weak linear correlation between SOC and BD in regularly disturbed soils, such as farmlands, where anthropogenic activities frequently alter soil bulk density, may be misleading when estimating bulk density-dependent SOC. This finding suggests the need for further research into varying degrees of anthropogenic disturbance in soil to confirm these results. While the site-specific nature of the findings warrants caution with respect to generalization, they provide valuable insights for carbon monitoring, climate actions, ecosystem health, and land-use management in similar traditional farming systems and degraded forests, particularly in data-poor regions.

Erosive Rainfall Thresholds Identification Using Statistical Approaches in a Karst Yellow Soil Mountain Erosion-Prone Region in Southwest China

Karst yellow soil is one of the most important cultivated soils in southwest China. At present, only a few studies have dealt with rainfall erosivity and erosive rainfall thresholds in the karst yellow soil region. This paper utilizes statistical methods to identify erosive rainfall thresholds and slope erosion-prone areas in the Qianzhong region. This analysis is based on long-term experimental data from 10 experimental stations and 69 experimental plots within the region in 2006 to 2022. The findings show the following: The rainfall amount threshold was 12.66 mm for woodland plots, 10.57 mm for grassland plots, 9.94 mm for farmland plots, and 8.93 mm for fallow plots. Soil and water conservation measures in forestry and grassland effectively increase the rainfall amount thresholds. Compared to farmland, the rainfall threshold increased by 27.32% for woodland and 6.32% for grassland. Bare land and farmland are erosion-prone areas in the karst yellow soil region. The erosive rainfall thresholds for farmland plots with slopes of 13°, 15°, 20°, 23°, and 25° were 10.41 mm, 10.28 mm, 9.66 mm, 9.52 mm, and 9.15 mm, respectively. With the increase in the 13–25° slope gradient of farmland, the initial rainfall required for runoff generation leads to a reduction. The wrong selection indices (WSI) of all landcover plots were less than 10%, and the efficiency indices (EFF) were between 80.43% and 90.25%. The relative error index (REI) of the erosive rainfall thresholds for all landcover runoff plots was less than 0.50%, very close to 0, indicating that these thresholds have small errors and high accuracy. This study gained a better understanding of natural rainfall-induced erosion characteristics in the study area, determined rainfall thresholds for distinguishing erosive rainfall events from non-erosive across different landcover types, and reduced the workload of calculating rainfall erosivity while enhancing the accuracy of soil erosion forecasting and simulation in the karst mountain yellow soil area.

Interpretation of Soil Characteristics and Preferential Water Flow in Different Forest Covers of Karst Areas of China

Soil hydrology seriously affects the prevention of desertification in karst areas. However, water infiltration in the different soil layers of secondary forests and artificial forests in karst areas remains uncertain. This lack of clarity is also the factor that constrains local vegetation restoration. Therefore, monitoring and simulating the priority transport of soil moisture will help us understand the shallow soil moisture transport patterns after artificial vegetation restoration in the local area, providing a reference for more scientific restoration of the ecological environment and enhancement of carbon storage in karst areas. The integration of soil physical property assessments, computed tomography (CT) scanning, dye tracing studies, and HYDRUS-2D modeling was utilized to evaluate and contrast the attributes of soil macropores and the phenomenon of preferential flow across various forestland categories. This approach allowed for a comprehensive analysis of how the soil structure and water movement are influenced by different forest ecosystems and infiltration head simulations (5 mm, 15 mm, 35 mm, and 55 mm) to elucidate the dynamics of water movement across diverse soil types within karst regions, to identify the causes of water leakage due to preferential flow in secondary forests, and to understand the mechanisms of water conservation and reduction in artificial forests adopting a multifaceted approach. This study demonstrated that (1) the soil hydrological capacity of a plantation forest was 20% higher than a natural forest, which may be promoted by the clay content and distribution. (2) Afforestation-enhanced soils in karst regions demonstrate a significant capacity to mitigate the loss of clay particles during episodes of preferential flow and then improve the soil erosion resistance by about 5 times, which can effectively control desertification in karst area. (3) The uniform distribution of macropores in plantation forest soil was conducive to prevent water leakage more effectively than the secondary forest but was incapable of hindering the occurrence of preferential flow. The secondary forest had a very developed preferential flow phenomenon, and soil clay deposition occurred with an increase in depth. (4) Moreover, the results for preferential flow showed that the matrix flow depth did not increase with the increase in water quantity. Short-term and high-intensity heavy rainfall events facilitated the occurrence of preferential flow. Infiltration along the horizontal and vertical directions occurred simultaneously. These results could facilitate a further understanding of the contribution of the plantation to soil amelioration and the prevention of desertification in karst areas, and provide some suggestions for the sustainable development of forestry in karst areas where plantation restoration is an important ingredient.

Remote Sensing Inversion of Soil Organic Matter Content in Straw-Returned Fields in China’s Black Soil Region

China’s black earth region is the country’s corn golden belt, and returning corn straw to the field not only helps improve the Soil Organic Matter (SOM) content and soil fertility, but also resolves environmental pollution caused by straw burning. To study the effects of different years and amounts of straw returned to the field on SOM content, this study used soil sampling data from a conservation tillage experimental base in Gaojia Village, Lishu County, combined with indoor measurements of imaging spectral data, to establish a prediction model of SOM content by applying partial least squares regression, and inverting the SOM content in the study area. The results showed that the PLSR model accuracy using indoor measured soil imaging spectral data as the independent variable was high. The accuracy coefficients of samples with different field return and different field return amounts, R2, were 0.9176 and 0.8901, respectively, which better predicted SOM content. In the 0–50 cm tillage layer, the highest average SOM content of 39.73 g/kg was found under the NT-1 treatment with different no-tillage straw return year treatments. The depth of the tillage layer in the typical black soil region of Northeast China is around 0–20 cm, and the most significant increase in SOM content was observed in the experimental samples under the NT-1 treatment. SOM content in NT-1 treatment increased by 31.83% compared with CK-1, 68.24% compared with CK-2, 72.18% compared with NT-0, 699.48% compared with NT-2, and 311.44% compared with NT-3, respectively. The highest SOM content of 31.9 g/kg was found in NT-100 under the different treatments of different years of field return. At the 0–20 cm soil layer, the SOM content increases most significantly under NT-100 treatment, which is the most suitable treatment method for straw return to the field. And NT-100 is 22.09% higher than CK-1, 55.36% higher than CK-2, 58.99% higher than NC-0, 115.95% higher than NT-33, and 48.72% higher than NT-67, respectively. This study provides data that can support the conservation of soil ecosystem diversity and sustainable soil use, and it also enriches the application of the PLSR model application.

Grain yield and nitrogen cycling under conservation agriculture and biochar amendment in agroecosystems of sub-Saharan Africa. A meta-analysis

Soil nitrogen (N) is one of the most limiting factors affecting crop production in sub-Saharan Africa (SSA). Here we conducted a meta-analysis on the effect of climate smart agricultural (CSA) practices (conservation agriculture (CA) and/or biochar (BC)) application on: (1) soil nitrate-N (NO3-N), nitrous oxide (N2O) emission, biological N2-fixation, percent of nitrogen derived from the atmosphere (%Ndfa), grain yield and nitrogen use efficiency (NUE), (2) the role of soil properties and regions on grain yield and N cycling under CA and/or BC biochar application; and (3) the relationship between inorganic N fertilizer and NO3-N, N2O emissions, NUE and grain yield. We synthesized 87 unique papers, from 15 countries in SSA with 1643 paired observations. On average across all studies, CA and/or BC significantly increased grain yield and NUE, compared to conventional practices. Residue retention resulted in a significant increase in soil NO3-N and N2O emission, compared to conventional practices. Our analysis further indicates that BC application significantly increased biological N2-fixation, grain yield and NUE. Auxiliary soil parameters also affected grain yield and N cycling. Grain yield was significantly influenced by total organic carbon classes (TOC), whereby highest grain yield was recorded under CSA in soils with 0.5–1 % TOC, compared to soils with < 0.5 % TOC and > 1 % TOC. In addition, total nitrogen (TN) significantly affected the response ratio of CSA and conventional agriculture on N2O emission and biological N2-fixation. N2O emission increased significantly in soils with < 0.05 % TN, while biological N2-fixation increased significantly in soils with > 0.2 % TN. Increasing N fertilizer use significantly increased the response ratio of CSA and conventional agriculture on N2O and NO3-N while significantly reducing the response ratio of yield and NUE. The gap in yield and NUE between CSA and conventional agriculture practises was more pronounced at lower N rates of 0 kg ha−1 and narrowed as N input increased to 120 kg ha−1; this implies that, CSA offers more benefits compared to conventional agricultural practices under low N rates.

Provenance of soil parent materials in relation to regional environmental changes in the Songnen Plain, Northeast China

Parent materials have a strong control on soil formation process and soil properties, understanding their provenance can provide important information for soil genesis, classification, and regionalization. The Songnen Plain in northeast China has large areas of Phaeozems and Chernozems, popularly known as “black soils”, but their parent material provenance and sedimentary processes are still unclear. Therefore, this paper analyzes the types and formation process of soil parent materials in the context of regional environmental changes. This analysis is based on the characteristics of grain size distribution and quartz particle morphology at the regional and profile scales. The results indicate that aeolian loess is the predominant parent material. For instance, the surface of quartz particles exhibits characteristics indicative of mechanical impact, which is produced during the process of wind transportation. The particle size distribution curve displays a bimodal pattern, and the soil particle size tends to become finer from west to east. However, in some areas, the soil is influenced by river or lake sediments. The main source areas of aeolian deposits are likely the Gobi and sandy land in the upwind direction of the study area, while the Songhua River alluvial deposits only provide source material in local areas. High-resolution grain size analysis and K-feldspar single-particle OSL chronology show that from the Last Glacial Maximum to the Early Holocene, far-source materials dominated the deposition process. In the Middle Holocene, climate warming increased the frequency of dust activities and accelerated the deposition process. In the late Holocene, climate fluctuations and intensified human activities led to more intense dust storms in the provenance area, which in turn promoted the continuous accumulation of parent materials for soils that developed into Phaeozems and Chernozems.

Impact of freeze–thaw cycling on the stability and turnover of black soil aggregates

During freeze–thaw cycling, aggregates undergo a dynamic change in breakdown–formation (turnover), however, how the turnover occurs between aggregates of various particle sizes is not clear. To clarify the influence of freeze–thaw cycling on the dynamic changes in the particle size of soil aggregates, soil aggregates from the Black Soil Region of Northeast China were selected as the research objects. The study conducted in situ dynamic monitoring experiments, innovatively applying the rare earth oxide (REO) tracer method to natural conditions of freeze–thaw cycles (autumn freeze–thaw period, freezing period, and spring freeze–thaw period), accurately tracking the turnover paths and quantifying the turnover rates between aggregates of various particle sizes. The results revealed that the total value of the formation paths of the 2–5 mm aggregates and 0.25–2 mm aggregates increased during the autumn freeze–thaw period. The number of freeze–thaw cycles and accumulated snowfall were significantly positively correlated with aggregate stability, with an increase in the number of freeze–thaw cycles and accumulated snowfall resulting in an increase in the proportion of aggregates > 0.25 mm, which improved aggregate stability. In addition, the total value of the breakdown path of macro-aggregates increased during the spring freeze–thaw cycling period. Soil moisture was significantly negatively correlated with aggregate stability, with increased soil moisture resulting in a decrease in the percentage of aggregates > 0.25 mm, which resulted in a decrease in aggregate stability. The study can provide a reference understanding for the effects of freeze–thaw cycles on the structure of black soil and provide a theoretical basis for improving the quality of arable land.

Canavanine Content Quantification in Processed Bitter Vetch (Vicia ervilia) and Its Application as Flour in Breads: An Analysis of Nutritional and Sensory Attributes.

Bitter vetch (Vicia ervilia Willd.) is a traditional Mediterranean-West Asian legume, mainly used as livestock feed because of its toxic non-proteinogenic amino acid, canavanine. However, historical sources suggest its past human consumption. Currently, bitter vetch is a minor crop confined to marginal soils in semi-arid regions, presenting a potential alternative protein source amid projected climate changes. This study evaluated the nutritional and sensory attributes of bitter vetch seeds processed through various household methods. Germination and cooking significantly reduced the canavanine content by 28% and 60%, respectively. Incorporating bitter vetch flour (BVF) into wheat bread enhanced protein and fiber contents without substantially altering carbohydrate and lipid levels, and the baking process reduced the canavanine content by 40%. Bitter vetch flour enriched the bread with iron and calcium, contributing significantly to their daily nutritional intakes. Sensory evaluations indicated positive reception for bread with 12% BVF, achieving a balance between nutritional enhancement and consumer acceptance. This study identifies bitter vetch seeds as a valuable resource for improving bread formulations with corrected gluten contents and enhanced protein quality, as measured using protein-digestibility-corrected amino acid score (PDCAAS) values. With strategic processing and formulation adjustments, bitter vetch has the potential to re-emerge as a feasible high-protein grain crop, promoting sustainable farming.

The influence of plant traits on soil microbial communities varies between arid and mesic grasslands

Abstract Background and aims Both soil properties and plant traits shape the diversity, composition and functions of plant-associated soil microbial communities. However, the relative influence of these factors is poorly understood, as are interactive effects between factors and the degree to which their influence varies among climate zones. Methods To address this gap, we compared the diversity and composition of soil microbial communities associated with co-occurring C3 and C4 grasses from arid and mesic environments, and plant traits influencing them. Results Climate emerged as the main determinant of plant traits and microbial community properties. Within each climatic region, above- and below-ground traits and soil properties differentially affected microbial community composition, and their relative influence varied among communities. In both mesic and arid environments aboveground traits related to quantity and quality of leaf litter (e.g., specific leaf area, leaf C content) and nutrient availability were the most influential variables for community composition. However, in arid regions, belowground traits (i.e., root tissue density and specific root area) significantly contributed to structure the eukaryotic community, supporting the role of roots as important driver of eukaryotic differentiation in constrained environments. Further, the presence of C4 plants in the arid region resulted in higher relative abundance of ciliate protists and higher recruitment of potentially beneficial microbial community members from green algae mediated by drought adaptation traits (e.g. decreased abundance of fine roots). Conclusions Overall, our study revealed a differential response of microbial communities to environmental conditions, suggesting that soil microbial community composition is influenced by trade-offs between host adaptive traits across distinct climatic regions.

Effect of reinforcement layer on dynamic wetting behavior and accumulative deformation of granite residual soil subgrade

This paper contributes to investigate the impact of reinforcement layer on the dynamic wetting behavior and accumulative deformation of granite residual soil subgrade of expressways in southern China. The wetting test combined with vehicle test and vibration test were conducted in two selected test sections with a reinforcement layer (WRL) and without a reinforcement layer (NRL), respectively. The influence of vehicle speed, moving load, repeated loading, and loading number on the dynamic stress, dynamic acceleration, and dynamic displacement of both the NRL and WRL subgrades was explored under different wetting conditions. The impact of the wetting number and traffic loading on the time-domain characteristics of the dynamic response and the accumulative deformation were revealed. The results indicate that the WRL subgrade can effectively reduce the dynamic response compared to the NRL subgrade. The influence depth of the WRL subgrades is 1.3 m, while the influence depth of the NRL subgrades is 3.3 m. Dynamic stress, dynamic acceleration, and dynamic displacement increase with increasing the wetting number, moving load, and repeated loading. The peak values of the dynamic stress and dynamic acceleration time-domain curves for the NRL subgrade are 27 % and 24 % higher than those of the WRL subgrade, respectively. At 3 million loading numbers, the accumulative deformation of the NRL subgrades is 53.7 % higher than that of the WRL subgrade. The dynamic stress, dynamic acceleration, and dynamic displacement of the NRL subgrade are generally higher than those of the WRL subgrade. The predictive models are established to correlate the wetting, dynamic load, and the dynamic response for both NRL and WRL subgrades. The dynamic stress, dynamic acceleration, and dynamic displacement measured in the vibration test are generally higher than those measured in the vehicle test. The research results provide a reference for the design of durability subgrade in granite residual soil regions.

Mechanism and structure of micro-nanofluid directional heat conduction in asphalt pavement in plateau permafrost regions

Solar radiation in plateau permafrost regions is strong. The asphalt pavement strongly absorbs and slowly dissipates heat, leading to significant heat accumulation on the pavement. This accumulation disturbs the underlying permafrost and eventually causes serious pavement damage. To improve the heat resistance and dissipation capabilities of asphalt pavement, a nanofluid directional heat conduction structure (N-DHCS) was suggested and analyzed in this paper. The designed structure can resist heat in the daytime due to the low thermal conductivity of liquid and dissipates heat at night through natural convection. The finite element method and laboratory irradiation experiment were employed to performed thermal analyses of N-DHCS. The results demonstrated that establishing the N-DHCS in asphalt pavements can enhance active heat dissipation capacity, which is beneficial for protecting the frozen soil in plateau permafrost regions.