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Summary: Knowledge of differential life‐history strategies in arbuscular mycorrhizal (AM) fungi is relevant for understanding the ecology of this group and its potential role in sustainable agriculture and carbon sequestration. At present, AM fungal life‐history theories often focus on differential investment into intra‐ vs extraradical structures among AM fungal taxa, and its implications for plant benefits. With this Viewpoint we aim to expand these theories by integrating a mycocentric economics‐ and resource‐based life‐history framework. As in plants, AM fungal carbon and nutrient demands are stoichiometrically coupled, though uptake of these elements is spatially decoupled. Consequently, investment in morphological structures for carbon vs nutrient uptake is not in competition. We argue that understanding the ecology and evolution of AM fungal life‐history trade‐offs requires increased focus on variation among structures foraging for the same element, that is within intra‐ or extraradical structures (in our view a 'horizontal' axis), not just between them ('vertical' axis). Here, we elaborate on this argument and propose a range of plausible life‐history trade‐offs that could lead to the evolution of strategies in AM fungi, providing testable hypotheses and creating opportunities to explain AM fungal co‐existence, and the context‐dependent effects of AM fungi on plant growth and soil carbon dynamics. [ABSTRACT FROM AUTHOR]

Potassium (K) is the primary limiting nutrient for cassava, being essential to achieve sustainably satisfactory cassava yields in low K reserve sandy soils that require proper K fertilization to avoid depleting the soil K reserve. Soil K dynamics, the growth, and yield responses of cassava were investigated using varying K fertilizer rates (0, 25, 50, 75, 100, and 125 kg K2O/ha). Four on-farm experiments were conducted in major cassava-producing areas, Northeast Thailand during 2019–2021 year. Cassava responded positively to K, producing yield increases up to 132%, with the highest tuber yield obtained being in the range 100–125 kg K2O/ha. Mineral K was the main K source for cassava grown without K fertilization, which resulted in the poorest growth and yield quantities. Potassium fertilization significantly promoted the uptake of K by cassava, especially in the tuber, causing a negative K balance due to the large removal from the soil, even when the K fertilizer compensated to some degree. Potassium use efficiency of cassava was low, particularly with K fertilization at the highest rate, which reflected intense leaching of the soil. The critical level of soil-available K, identified using a linear-plateau model, was 40.55 mg/kg for 90% relative yield, suggesting the potential to increase K use efficiency through better fertilization guidelines. Our findings suggested that K fertilization of cassava annually is advisable for better yields and to avoid progressive depletion of the soil K capital, even though the residual K from K fertilizer contributed to available K in soils. [ABSTRACT FROM AUTHOR]

Summary Forest soils play a pivotal role as global carbon (C) sinks, where the dynamics of soil organic matter (SOM) are significantly influenced by ectomycorrhizal (ECM) fungi. While correlations between ECM fungal community composition and soil C storage have been documented, the underlying mechanisms behind this remain unclear. Here, we conducted controlled experiments using pure cultures growing on naturally complex SOM extracts to test how ECM fungi regulate soil C and nitrogen (N) dynamics in response to varying inorganic N availability, in both monoculture and mixed culture conditions. ECM species dominant in N‐poor soils exhibited superior SOM decay capabilities compared with those prevalent in N‐rich soils. Inorganic N addition alleviated N limitation for ECM species but exacerbated their C limitation, reflected by reduced N compound decomposition and increased C compound decomposition. In mixed cultures without inorganic N supplementation, ECM species with greater SOM decomposition potential facilitated the persistence of less proficient SOM decomposers. Regardless of inorganic N availability, ECM species in mixed cultures demonstrated a preference for C over N, intensifying relatively labile C compound decomposition. This study highlights the complex interactions between ECM species, their nutritional requirements, the nutritional environment of their habitat, and their role in modifying SOM. [ABSTRACT FROM AUTHOR]

Plant economics, the way plants allocate and utilize resources, affect multiple soil processes through interactions with root and associated microbial communities. However, the interplay between plant economics and microbial ecological strategies remains poorly understood, which is crucial for integrated manipulation of plant‐ and microbe‐mediated functions in mitigating climate change and sustaining soil health. We used a field experiment with 11 cover crop species grown monocultures in the same base soil to test whether microbial ecological strategies are associated with plant economic strategies and if their interactions are linked to soil functions. A principal component analysis (PCA) was performed on root and leaf traits to identify the loadings of cover crop species on the plant trait space. Metagenomic analysis of rhizosphere microbial communities was conducted to infer their ecological strategies based on genetically encoded community‐aggregated traits. We found a synchronous relationship between the conservation gradient of plant economic strategies and the trade‐offs in microbial ecological strategies. Conservative plant strategists, such as Lolium multiflorum, Triticum turgidum and Brassica juncea, fostered microbial communities characterized by high growth yield potentials (Y‐strategies). This included increased microbial carbon fixation pathways, citrate cycle, ribosome and valine, leucine and isoleucine biosynthesis. As a result, microbial metabolic efficiency improved, shown by higher microbial biomass carbon content and a lower metabolic quotient (qCO2), led to enhanced soil organic carbon accumulation. In comparison, acquisitive plants like Astragalus sinicus, Vicia villosa, Trifolium incarnatum and Medicago sativa stimulated microbial resource‐acquisition strategies (A‐strategies). This included enhanced bacterial chemotaxis, secretion systems, biotin metabolism and cell motility pathways, which in turn increased soil exoenzyme activity and accelerated soil nitrogen mineralization. Consequently, these species enhanced soil nitrogen availability and had substantial feedbacks on subsequent main crop productivity. Synthesis. This study demonstrates how plant economic strategies influence the balance between different microbial ecological strategies, specifically the trade‐offs in Y‐ and A‐strategies. These interactions exert control over carbon and nitrogen dynamics in the soil ecosystem. The findings provide insights for implementing nature‐based solutions to improve agroecosystem management practices. [ABSTRACT FROM AUTHOR]

A lack of high‐density rootzone soil moisture (θRZ) observations limits the estimation of continental‐scale, space‐time contiguous θRZ dynamics. We derive a proxy of daily θRZ dynamics — active rootzone degree of saturation (SRZ) — by recursive low‐pass (LP) filtering of surface soil moisture (θS) within a terrestrial water‐energy coupling (WEC) framework. We estimate the LP filter parameters and WEC thresholds for the piecewise‐linear coupling between SRZ and evaporative fraction (EF) at remote sensing and field scale over the Contiguous U.S. We use θS from the Soil Moisture Active‐Passive (SMAP) satellite and 218 in‐situ stations, with EF from the Moderate Resolution Imaging Spectroradiometer. The estimated SRZ compares well against SMAP Level‐4 estimates and in‐situ θRZ, at the corresponding scale. The instantaneous hydrologic state (SRZ) vis‐à‐vis the WEC thresholds is proposed as a rootzone soil moisture stress index (SMSRZ) for near‐real‐time operational agricultural drought monitoring and agrees well with established drought metrics. Plain Language Summary: Rootzone soil moisture plays a vital role in agricultural, hydrological, and ecosystem processes. The available spaceborne satellites for monitoring soil moisture can only capture variability in a shallow soil layer at the surface, typically limited to the top 5 cm. Hence, spatiotemporally continuous estimation of rootzone soil moisture dynamics typically relies on soil moisture estimates from land‐surface models, which are subject to errors in the surface meteorological forcing data, process formulations, and model parameters. Some studies suggest that the rootzone soil moisture dynamics can be estimated by filtering the high‐frequency variability in the surface soil moisture. However, such "filters" require observed rootzone data (often unavailable at high spatial density) for calibration. This study uses the relationship between surface soil moisture and evaporative fraction derived using spaceborne observations from the Soil Moisture Active Passive mission and the Moderate Resolution Imaging Spectroradiometer to estimate rootzone soil moisture dynamics for the Contiguous U.S. at 9 km grid resolution. We further demonstrate that this approach can be extended into a near‐real‐time agricultural drought monitor to assess drought impacts on vegetation using surface soil moisture observations. Key Points: Terrestrial water‐energy coupling is used to parameterize low‐pass filter to estimate rootzone dynamics from surface soil moistureRootzone degree of saturation and water‐energy coupling thresholds are estimated using evaporative fraction and surface soil moistureSMAP‐based rootzone degree of saturation can used for operational, near‐real‐time agricultural drought monitoring over Contiguous U.S [ABSTRACT FROM AUTHOR]

Agricultural intensification has increased the consumption of inputs, mainly fertilizers, which may increase emissions of greenhouse gases (GHG). The improvement of our knowledge on GHG dynamics in the soil is mandatory to optimize the use of fertilizers and reduce environmental impacts. We developed an electronic sensor prototype based on Arduino to monitor concentrations of carbon dioxide (CO2), ethylene (C2H4), ammonia (NH3), and nitrogen oxides (N2O/NOx) in the soil air in a greenhouse experiment with soybean (Glycine max L.) under two treatments: single inoculation (Bradyrhizobium spp.) or triple co-inoculation (Bradyrhizobium spp. Azospirillum brasilense and Pseudomonas fluorescens) in a completely randomized design. One-way analysis of variance, as well as correlation between plant traits at 35 days of emergence and the average daily concentration of gases in the soil air were performed. Although not affecting plant growth or yield-related traits, co-inoculation increased CO2, while decreased NOx concentrations compared with single inoculation, whereas C2H4 emission changed with the plant growth stage. Although co-inoculation increased respiration, decreased N losses by denitrification, mitigating the total emissions of GHG. The prototype showed to be efficient for monitoring GHG across the experiment at a low cost and easy use, contributing for monitoring GHG concentrations in the soil air. [ABSTRACT FROM AUTHOR]

This review article focuses on the complex relationships between forests and water, particularly the effects of forests on streamflow during meteorological droughts. The impact of forests on water resources is a long‐standing research topic, but there are also many common beliefs that are not based on scientific evidence or only selective evidence. We critically examine the origin of some of the common public misconceptions and review the wealth of studies on how forests impact precipitation, soil water dynamics, evapotranspiration, and streamflow. Generally, reforestation increases evapotranspiration and decreases groundwater recharge and streamflow. However, some of the evaporated water will return as precipitation, potentially offsetting some of the increased evapotranspiration losses. Where reforestation leads to more extensive infiltration and recharge due to the effects of forests on the soil's hydraulic properties, it might increase streamflow during dry periods. Although these individual processes have been studied, predicting the impacts of forests on streamflow remains challenging as the effects are site‐specific and depend on many factors, such as the climate, the forest‐ and soil‐characteristics before and after reforestation, and the hydrogeological setting. However, a more accurate and nuanced understanding of the role of forests on hydrology and a better ability to predict where and when the net effects of reforestation are positive or negative is crucial for sustainable forest and water management.This article is categorized under: Science of Water > Science of Water Science of Water > Water and Environmental Change Science of Water > Hydrological Processes Engineering Water > Sustainable Engineering of Water [ABSTRACT FROM AUTHOR]

The observed climate changes and increasing groundwater levels in the forest-steppe region should be reflected in the water regime of meadow-chernozemic soils (Gleyic Chernozems). This article analyzes the seasonal dynamics of volumetric moisture content in a fallow Gleyic Chernozem (Siltic, Hyperhumic, Pachic) and two arable Gleyic Chernozems (Siltic, Aric, Hyperhumic, Pachic), as well as the level of groundwater in the Tokarevskii district of Tambov oblast during the period from fall 2022 to summer 2023. The obtained data are compared with regime observations of volumetric moisture content and groundwater levels in these soils performed in 1969–1971. The use of automated monitoring systems for the soil moisture content and groundwater levels has allowed continuous data collection on soil moistureand detailed tracking of seasonal changes. The fallow meadow-chernozemic soils is characterized by higher moisture levels compared to arable soils; the upper horizons of cultivated soils are characterized by a higher frequency of wetting–drying periods and a shorter continuous duration of these periods, which is confirmed both by moisture monitoring data and by the morphological features of the soils, such as the form of carbonate pedofeatures and the depth of their detection. During the observation period in 2022–2023, the meadow-chernozemic soils were relatively dry, despite the higher than normal annual precipitation. Wilting point moisture in the top 20-cm layer of cultivated soils was established from March 2023, and in the fallow soil, from the end of April 2023. Periods with the moisture content exceeding the field capacity within the 60-cm-thick upper soil layer were not observed during the entire observation period. The soils were drier than in the dry year of 1972, when the moisture content was less than the wilting point in the upper part of the profile from June to September. In the wet years of 1969–1970, the moisture content did not drop below the wilting point in the upper 20-cm layer throughout the observation period. The main reason for this difference in the moisture content is the change in the groundwater level: in 2022–2023, the groundwater level was more than 4 m deep, whereas in 1969 it did not go deeper than 2 m, and in 1971, deeper than 4 m. As a result, the soil's uptake of moisture through capillary rise did not occur in 2022–2023, and the water regime of the meadow-chernozemic soils more closely resembled the water regime of typical chernozems (Haplic Chernozems). [ABSTRACT FROM AUTHOR]

Context: Process-based crop growth models can explain soil and crop dynamics that influence the optimal N rate for crop production. Currently, there is a lack of understanding regarding the accuracy of process-based models for site-specific zones within fields, as well as the key factors that need to be considered when calibrating these models for zone-specific economic optimum N rate (EONR). Objective: We calibrated the Agricultural Production Systems sIMulator (APSIM) model in contrasting zones within fields, quantified the model performance, and used the calibrated model to develop long-term corn yield response to N to assess the temporal variability between zones and sites to assist decision making. Methods: We conducted four N rate experiments (2 fields × 2 zones within a field) over two years in southeast Nebraska. Experimental data were used to calibrate and test the APSIM model. APSIM simulated corn yield response to N for each zone and site was obtained by running numerous iterations of the calibrated model at different N rates. Observed and simulated corn yield response to N rate were analyzed with statistical models to estimate the EONR. Results and conclusions: The APSIM model predicted corn yield over 11 historical years with a relative root mean square error (RRMSE) of 12% and yield at EONR in the N studies with RRMSE of 8.8%. The simulated EONR was lower than the observed EONR across sites, years, and zones with greater error than yield. The simulated yield increase with N fertilization was under-estimated in fine textured soils and over-estimated in medium textured soils. Long-term corn yield response to N showed that temporal variation in simulated EONR was greater than spatial variation. Long-term EONR and yield at EONR increased with increasing rainfall, while yield at zero N was greatest in normal years. Temporal variation was driven primarily by year-to-year variation in N loss (CV of 67% ± 9.5). Soil texture, hydrological properties, water table, and tile drainage were key variables for accurate site-specific model calibration. Improvements in simulating site-specific EONR may be realized by including in-situ or remotely sensed data for better estimation of N dynamics. We concluded that APSIM can provide valuable insights into systems dynamics in this region, but it can't provide precise N-rate estimates. Our study contributes to understanding of the within-field variability using simulation modeling. [ABSTRACT FROM AUTHOR]

Soil plays a critical role as the primary reservoir of phosphorus (P) in terrestrial ecosystems. Sequential fractionation has been extensively utilized to gain insights into the characteristics and dynamics of soil P. However, there is a knowledge gap regarding the different P pools in Nepalese soils. Therefore, this study aimed to investigate the impact of cropping systems on soil P fractions in the central mid-hills of Nepal. The study focused on four cropping systems: vegetable, fruit, rice, and maize-based systems, which exhibited variations in nutrient management, topography, and cropping intensity. A total of 240 soil samples (60 samples from each cropping system) were collected from multiple sites within the central mid-hill region. Standard analytical methods were used to determine the general parameters of the soils, while the sequential fractionation method was employed to assess the organic and inorganic P pools. The results indicated that the effect of cropping systems on soil pH, calcium carbonate (CaCO3) content, and the proportion of sand, silt, and clay was not statistically significant in terms of general parameters. However, significant differences were observed among the different cropping systems in organic matter (OM), electrical conductivity (EC), cation exchange capacity (CEC), and available phosphorus. Similarly, in terms of inorganic phosphorus fractions, loosely bound P (LB-P), aluminum bound P (Al-P), iron bound P (Fe-P), and reductant soluble P (RS-P) were significantly affected, while calcium bound P (Ca-P) did not show a significant difference. Furthermore, in terms of organic phosphorus fractions, labile organic P (L-Po), fluvic acid organic P (FA-Po), and non-labile organic P (NL-Po) exhibited significant differences, whereas moderately labile organic P (ML-Po) and humic acid organic P (HA-Po) did not show a significant difference. Additionally, reductant soluble P showed a significant difference, while total P did not differ significantly. The vegetable-based system exhibited higher levels of the majority of P fractions, followed by the fruit-based, maize-based, and rice-based systems. These findings emphasize the importance of considering cropping systems and their response to different phosphorus pools, as this knowledge can contribute to the development of improved soil phosphorus management strategies and promote sustainable agricultural practices in the region. [ABSTRACT FROM AUTHOR]

Although molecular characterization of soil organic carbon is crucial for understanding its dynamics, studies on reclaimed coal mine soil are comparatively limited. Therefore, the primary objective of this study was to ascertain the influence of tree species on the soil organic carbon content and molecular characteristics of soil organic carbon in a chronosequence of reclaimed coal mine soil. To investigate the effects of reclamation time on soil organic carbon characteristics, a chronosequence of three coal mine soil was used, each exhibiting different ages of reclamation: 8, 14, and 25 years. Along a re-vegetation age gradient of 8 to 25 years, the total soil organic carbon content increased. Within the 25 years of restored soil, the FTIR absorption intensities were lowest within the range of 2,920 and 2,850 cm−1, while they were highest within the range of 1,685, 1,425, and 1,285 cm−1which indicates presence of aromatic C=C. This shows that aromatic compounds contributed more significantly to the composition of soil organic carbon compared to aliphatic structures. Based on molecular characteristics, it is suggested that the soil organic carbon in 25-year old revegetated coal mine soil consists of aromatic and recalcitrant carbon. Among three tree species Dalbergia sissoo can be used for reclamation as quality and quantity of carbon found was higher under this tree species. In conclusion, the results indicated that the molecular properties of soil organic carbon were extremely important for understanding the dynamics of soil organic carbon in a restored coal mine soil chronosequence. [ABSTRACT FROM AUTHOR]

Background Aim Methods Results Conclusions Tropical ecosystem functioning is influenced by seasonal fluctuations in precipitation, but the impact on soil nutrient cycling and microbial stoichiometry is not fully understood.This study investigates the magnitude of intra‐annual fluctuations in nutrient availability and microbial biomass in a tropical forest soil by examining carbon (C), nitrogen (N), and phosphorus (P) pools.We analyzed the total, extractable, and microbial C, N, and P contents and their stoichiometry in Terra Firme Ferralsols, representative for the central Amazon basin.We observed intra‐annual variations in resource availability, particularly between wet and dry seasons. Despite relatively stable total C, N, and P stocks throughout the year, we observed a decrease in extractable organic C and available (Olsen) P and an increase in extractable N in the dry season compared to the wet season. Microbial biomass pools and stoichiometry also varied across sampling dates and soil depths: relative to microbial‐C and ‐N, microbial‐P decreased in both wet and dry season and increased in the transition from wet to dry season.Our research highlights intra‐annual variation in nutrient pools, particularly dynamic microbial carbon and nutrient fractions, in weathered tropical forest soils. [ABSTRACT FROM AUTHOR]

The intensification of the global hydrological cycle is anticipated to increase the variability of precipitation patterns. Brackish wetlands respond to changes in precipitation patterns by regulating the absorption and release of CO2 and H2O to maintain the stability of ecosystem functions. However, there is limited understanding of how the inter‐seasonal precipitation distribution (SPD) affects ecosystem CO2 and H2O exchange compared with annual precipitation totals.Here, we conducted four consecutive years of field experiments in a brackish wetland, manipulating the proportion of precipitation across different seasons while maintaining a constant annual precipitation total. We utilized five inter‐SPD proportions (+73%, +56%, control (CK), −56%, −73%) to examine the effects of SPD on ecosystem CO2 and H2O exchange.Our findings revealed that the annual ecosystem CO2 and H2O fluxes showed a trend of decreasing with the decrease in spring precipitation distribution. Among them, the annual net ecosystem CO2 exchange, evapotranspiration, carbon use efficiency and water use efficiency were shown to be more sensitive to decrease in spring precipitation distribution and increase in summer and autumn precipitation distribution. This negative asymmetric response pattern suggests that annual ecosystem CO2 and H2O exchange is primarily governed by seasonal precipitation variability, with spring soil water–salt dynamics identified as the key driver. Therefore, this association can be explained by the fact that drought of the early growth stage exacerbates soil salinization and inhibits vegetation colonization and growth, thereby greatly impairing the annual CO2–H2O exchange capacity of brackish wetlands.Our results emphasized that the spring extreme precipitation‐induced soil water–salt conditions will greatly influence CO2 and H2O exchange in brackish wetlands in the future. These findings are crucial for improving predictions of the carbon sequestration and water‐holding capacity of brackish wetlands. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Effective phosphorus (P) management is crucial for optimal blueberry production. However, a comprehensive understanding of phosphorus distribution across soil depths and types after two decades of blueberry cultivation remains a challenge. This study examines pH, EC, SOC (soil organic carbon), Total N (total nitrogen), and phosphorus fractions in soils from Japanese blueberry fields that have been cultivated for over 20 years. The soils selected for this study represent typical soils from long-term blueberry-growing regions in Japan, ensuring the relevance of the findings to these key agricultural areas. Soil samples were gathered from depths of 0–30 cm and 30–60 cm, revealing significant variations in phosphorus content that are influenced by soil properties and fertilization history. Soil types such as KS (Kuroboku soils) and FS (Fluvic soils) show higher Total P accumulation in deeper layers, whereas BFS (Brown Forest soils) and RYS (Red-Yellow soils) accumulate more in shallower layers. Long-term cultivation has led to greater non-labile phosphorus (NLP) accumulation in shallower layers of KS, BFS, and FS soils, indicating strong phosphorus fixation. BFS soil also exhibits increased organic phosphorus (NaOH-Po) at deeper depths. NaOH-Po and NaHCO3-Po, through their interactions with EC and pH, critically modulate the transformation of NLP into labile phosphorus (LP), thereby influencing overall phosphorus and nitrogen dynamics in the soil. These findings underscore the importance of tailored phosphorus fertilization strategies based on blueberry field characteristics, providing a basis for low-input phosphorus fertilization approaches. [ABSTRACT FROM AUTHOR]

While the influence of canopy trees on soils in natural and restored forest environments is well studied, the influence of understory species is not. Here, we evaluate the effects of outplanted native woody understory on invasive grass biomass and soil nutrient properties in heavily grass-invaded 30 + year-old plantations of a native N-fixing tree Acacia koa in Hawai'i. We analyze soils from under A. koa trees with versus without planted woody understory and compare these to soils from under remnant pasture trees of the pre-deforestation dominant, Metrosideros polymorpha where passive recruitment of native woody understory has occurred since the cessation of grazing. Simultaneously, we experimentally planted understory species at three times the density used by managers to see if this could quickly decrease grass biomass and change soil nutrient dynamics. We found that invasive grass biomass declined with understory planting in surveyed and experimental sites. Yet, woody understory abundance had no effect on N cycling. Short-term N availability and nitrification potential were higher under A. koa than M. polymorpha trees regardless of understory. Net N mineralization either did not differ (~ 1 mo) between canopy species or was higher (171 day incubations) under remnant M. polymorpha where organic matter was also higher. The only influence of understory on soil was a positive correlation with loss-on-ignition (organic matter) under M. polymorpha. We also demonstrate differential controls over N cycling under the two canopy tree species. Overall, understory restoration has not changed soil characteristics even as invasive grass biomass declines. [ABSTRACT FROM AUTHOR]

Over the past decades, anthropogenic disturbance of geological structures has been significantly documented in Slovakia, mainly driven by the national economy's demand for mining resources. Among these resources, brown coal, primarily mined in the Upper Nitra coal basin in the Prievidza district (Slovakia), has been essential. Mining activities around town of Handlová, and villages of Koš, Cígeľ and Sebedražie, particularly at the Cígeľ coal mine, have induced several geological defects. These defects, characterised by large cracks and local landslides, disrupt the hydrogeological conditions, significantly impacting the soil water regime stability of the forest ecosystems in these damaged areas. This study investigates the variability and dynamics of the soil water potential in a mining-affected site (Račkov laz) compared to an intact reference area (Čertove chodníky) between 2020 and 2022. Our findings suggest that mining activities could have substantial implications for the soil water regime and, consequently, the ecological stability of forest ecosystems. [ABSTRACT FROM AUTHOR]

Biological soil crusts (biocrusts) are crucial elements of desert ecosystems, exhibiting patchy distribution patterns across the soil surface and significantly impacting surface soil nutrient dynamics. However, the influence of biocrust patch units, serving as fundamental functional entities, on microbial nutrient restriction remains underexplored. This study conducted measurements on moss crust patches of varying sizes and subcrust soils. Stoichiometric analysis of extracellular enzyme activities (EEAs) related to carbon, nitrogen, and phosphorus was performed, along with vector and redundancy analyses to evaluate microbial nutrient limitation and key influencing factors. The findings reveal that both patch size and soil layer of biocrusts collectively influence soil nutrients and enzyme dynamics, with heightened enzyme activity observed in the crust layer. Vector analysis based on EEA stoichiometry indicates that moss crust patch size insignificantly impacts microbial nutrient restriction within the crust layer. However, microbial nitrogen restriction in the subcrust layer demonstrates a “single-peak” trend, initially increasing before gradually declining. This suggests that microorganisms in medium-sized crust patches exhibit peak activity, intensifying nutrient competition. This research underscores the pivotal role of biocrust patch units as fundamental functional entities, offering comprehensive insights into microbial metabolic constraints under crust cover. The findings underscore the significant implications of enzyme stoichiometric characteristics for desert land management and conservation. [ABSTRACT FROM AUTHOR]

Soil structure dynamics during a season depend on management practices and environmental factors. A lightweight autonomous robot (total mass: 3300–4100 kg, wheel load: 700–1200 kg, contact areas: 0.125 m², inflation pressures: 60–280 kPa) was used for sowing (October 2021) and weeding (May 2022) operations on an annually plowed sandy loam field. We took 579 cm³ soil cores at 10- to 18-cm depth in the crop area and wheel tracks before and after the operations to assess the impact from traffic and the potential recovery of topsoil structural properties. We measured air permeability and effective air-filled porosity in the laboratory, and X-ray CT scanned the samples to evaluate soil pore functionality. The first operation (conducted on a moist seedbed) had the largest impact, significantly compacting and reducing the air-filled porosity by 42% (from 0.21 to 0.12 m³ m−3) and decreasing air permeability by 75.8% (from 130 to 31.5 μm²). After 7 months, the crop area and wheel track showed signs of soil consolidation due to environmental factors but not decompaction. The second operation occurred on drier (water content 0.06 g g−1), stronger soil conditions (degree of compactness 100.8%), and recompaction of the wheel track was not observed. Traffic in weak soils can result in seasonal topsoil compaction despite the lighter wheel loads. However, due to the milder impacts, recovery rates might be faster for lightweight machinery than for heavy tractors. Multi-season studies are needed to assess the real potential of lightweight robots to minimize soil compaction risk. [ABSTRACT FROM AUTHOR]

A comprehensive analysis of the evolutionary dynamics of soil arches is crucial for accurately predicting soil deformations above sinkholes and assessing stability of underground structures. In this study, a series of trapdoor tests were conducted to investigate the progressive development of soil arching in dense sand. The particle image velocimetry (PIV) technique was utilized to capture soil deformation patterns, while fiber optic strain sensing cables were used to validate the displacement influence zone of soil by measuring strain profiles of the foundation. The ground reaction curves, derived from the measurements of earth pressure cells, shed light on the evolution process of stress redistribution and the rotation of principal stresses. The test results reveal that the formation of soil arching alters the overlying pressure on the trapdoor, transferring loads from yielding soil to adjacent stationary soil. The development of soil failure surfaces corresponded with vertical stress variations on the trapdoor. The strain profiles exhibited a characteristic trough above the trapdoor, along with double peaks at its edges. The measurements of micro-anchored strain sensing cables with small anchor spacings provided more accurate distributions of soil shear deformation. Furthermore, the orientation and magnitude of soil arching was inferred from principal stress rotations. The insights gained in this study are valuable for understanding the propagation of soil arching, offering potential implications for the execution of rational geotechnical design and the mitigation of related geological hazards. [ABSTRACT FROM AUTHOR]

For many drylands, both long‐ and short‐term drought conditions can accentuate landscape heterogeneity at both temporal (e.g., role of seasonal patterns) and spatial (e.g., patchy plant cover) scales. Furthermore, short‐term drought conditions occurring over one season can exacerbate long‐term, multidecadal droughts or aridification, by limiting soil water recharge, decreasing plant growth, and altering biogeochemical cycles. Here, we examine how experimentally altered seasonal precipitation regimes in a mixed shrub grassland on the Colorado Plateau impact soil moisture, vegetation, and carbon and nitrogen cycling. The experiment was conducted from 2015 to 2019, during a regional multidecadal drought event, and consisted of three precipitation treatments, which were implemented with removable drought shelters intercepting ~66% of incoming precipitation including: control (ambient precipitation conditions, no shelter), warm season drought (sheltered April–October), and cool season drought (sheltered November–March). To track changes in vegetation, we measured biomass of the dominant shrub, Ephedra viridis, and estimated perennial plant and ground cover in the spring and the fall. Soil moisture dynamics suggested that warm season experimental drought had longer and more consistent drought legacy effects (occurring two out of the four drought cycles) than either cool season drought or ambient conditions, even during the driest years. We also found that E. viridis biomass remained consistent across treatments, while bunchgrass cover declined by 25% by 2019 across all treatments, with the earliest declines noticeable in the warm season drought plots. Extractable dissolved inorganic nitrogen and microbial biomass nitrogen concentrations appeared sensitive to seasonal drought conditions, with dissolved inorganic nitrogen increasing and microbial biomass nitrogen decreasing with reduced soil volumetric water content. Carbon stocks were not sensitive to drought but were greater under E. viridis patches. Additionally, we found that under E. viridis, there was a negative relationship between dissolved inorganic nitrogen and microbial biomass nitrogen, suggesting that drought‐induced increases in dissolved inorganic nitrogen may be due to declines in nitrogen uptake from microbes and plants alike. This work suggests that perennial grass plant–soil feedbacks are more vulnerable to both short‐term (seasonal) and long‐term (multiyear) drought events than shrubs, which can impact the future trajectory of dryland mixed shrub grassland ecosystems as drought frequency and intensity will likely continue to increase with ongoing climate change. [ABSTRACT FROM AUTHOR]

This investigation explores the erosion dynamics in sandy soils triggered by underground pipeline fractures, applying transparent soil technology for visualization. Through this approach, the erosion process within the transparent soil model was meticulously recorded using photography, enabling the quantitative analysis of collapse pit dimensions over time. Results reveal that soil erosion primarily manifests directly above the pipeline fracture, varying significantly with hydraulic conditions. In scenarios devoid of water flow within the pipeline, an increase in collapse pit depth is halted, attributed to the accumulation and blockage of soil particles at the fracture point. Contrastingly, under half-pipe and full-pipe flow conditions, the depth of the collapse pit swiftly reaches the fracture site. The flow of water notably escalates the expansion rate of the erosion pit, especially above the rupture, leading to continuous enlargement of the central area and subsequent secondary and tertiary collapses at the pit's apex. The study further identifies the impact of water flow on soil scouring near the pipeline rupture, with pronounced effects in full-pipe flow, predominantly ahead of the rupture point, and less significant impacts observed in half-pipe flow scenarios. Differential image analysis facilitated the categorization of soil into distinct zones: collapsed, loosened, stable, and eroded, with a direct correlation observed between the extent of the loosened zone and the velocity of water flow. [ABSTRACT FROM AUTHOR]

Green gram is an excellent pulse crop with high economic and nutritional values. Optimal water and nutrient application can boost yield, water productivity, nutrient use, energy indices, and economic gains. The field experiment comprising three irrigation schedules (one irrigation at pre-flowering, two irrigations at pre-flowering and pod formation, and three irrigations at branching, pre-flowering and pod formation stages) and four nutrient management (control, 100% recommended fertilizer (RDF), farmyard manure at 5 t ha−1, and 100% RDF + FYM at 5 t ha−1) was arranged in a split-plot design with three replications during the summer seasons of 2016 and 2017. Based on the principal component analysis technique and economic assessment of all the treatments studied, three irrigations at branching, pre-flowering and pod formation stages with the recommended fertilizer plus FYM resulted in the maximum growth, yield components, seed yield (784 kg ha−1), stover yield (2288 kg ha−1), highest NPK uptake, total output energy, net energy gain, greatest gross return (USD 749.7 ha−1), net return (USD 331.7 ha−1) and higher BCR (1.79). However, maximum crop water productivity and irrigation water productivity (0.55 and 0.96 kg m−3, respectively) were recorded with a single irrigation at pre-flowering stage in tandem with full recommended fertilizer and farmyard manure. A linear relationship was detected between seed yield and seasonal crop evapotranspiration (ETc) at different nutritional levels. Seasonal water consumtion of 178 mm corresponding to an irrigation amount of 170 mm with a yield of 620 kg ha−1 and CWP of 0.36 kg m−3 was a balance for optimum seed yield, ETc and CWP. The 0–30 cm depth of the root zone profile contributed 80–84% while the 30–60 cm depth accounted for 16–20% of total soil moisture depletion. Based on the physical and financial outputs, a three-irrigation schedule coupled with the full recommended fertilizer and manure was identified as the best management strategy for green gram production and can thus be recommended to farmers of non-saline coastal soils in eastern India. [ABSTRACT FROM AUTHOR]

Second‐generation biofuel (e.g., ethanol, renewable diesel) can be made from crop residues. However, the availability of residues for biofuel production is uncertain, because farmers have the option to grow different crops and use the residues for alternative purposes, such as livestock bedding and feed, or leave them in the field to improve soil quality. Taking Canadian wheat straw supply as an example, we develop a dynamic programming model to investigate a farmer's wheat straw supply decision in response to different wheat straw and grain prices. Our model considers crop choices between wheat and canola in the context of disease risk, the trade‐off between the immediate payoffs a farmer may receive from bailing and selling wheat straw, and the long‐term adverse effects that removing wheat straw from the soil surface may have on wheat and canola yields. The results from this study provide insights into how farm‐level supply decisions, in response to wheat straw price changes, affect soil quality dynamics and scale up to regional wheat straw supply for biofuel production. This information also has implications for land use change and the sustainability of feedstock supply for biofuels. [ABSTRACT FROM AUTHOR]

The recent increase in the frequency of extreme weather events and declining soil biodiversity in global agricultural ecosystems make it crucial to assess the daily dynamics of soil communities in fields. To elucidate the daily dynamics of ground-dwelling invertebrate communities, their communities were monitored temporally using infrared camera traps in field farmland during and following an extremely high-temperature (EHT) event in summer 2022 in Ningbo City, China. Nine taxa and 1,147 individuals of the ground-dwelling invertebrate community were photographed in the 176,256 images. There were no significant differences in the taxonomic richness and abundance of the total ground-dwelling invertebrate communities during and following the EHT event. The abundance of ants was significantly decreased following the EHT event, whereas the abundance of other taxa was not. Significantly daily dynamics and obvious differences between each day in taxonomic richness, abundance of ground-dwelling invertebrate community, and abundance of each taxon were not observed during and following the EHT event. The results of this study showed that the daily dynamics of richness and abundance of the ground-dwelling invertebrate community and the abundance of each taxon were not significant during and following the EHT event. Overall, this study provides a useful monitoring method to observe the daily dynamics of ground-dwelling invertebrates in field farmlands and suggests that the daily dynamics of soil fauna communities should be further studied when assessing the effects of climate change on soil biodiversity. [ABSTRACT FROM AUTHOR]

The soil freeze-thaw (FT) state plays a significant role in cold ecosystems by influencing hydrology, geomorphology, ecology, thermodynamics, and soil chemistry. As climate change alters the frequency and timing of FT events, regions, such as the Tibetan Plateau and other subarctic permafrost zones, face significant environmental shifts, including land subsidence, altered hydrological processes, and carbon balance disturbances. This study aimed to detect frozen, thawed, and transition periods, with a particular emphasis on the identification of critical transition periods. A new approach called Percentile-based Freeze-Thaw Identification (PFTI) was applied to identify the three FT periodsusing C-band Synthetic Aperture Radar (SAR) data, specifically using Sentinel-1 VV and VH polarizations in both ascending and descending orbits. The PFTI approach is based on the Seasonal Threshold Approach (STA) with some modifications. We assessed the performance of PFTI against STA and validated it using the in-situ soil FT index. PFTI slightly improved the STA by 4% to 6% in detecting FT cycles over the Nagqu area of the Tibetan Plateau and Stordalen Mire in northern Sweden from 2017 to 2022. Moreover, PFTI demonstrated an accuracy of 94% without and 70% with transition periods in the Stordalen Mire, and 77% without and 50% with transition periods in the Nagqu area, as validated by in situ measurements. This study demonstrates the potential of PFTI on a monthly scale for detecting frozen, thawed, and transition periods on a regional scale to better monitor shifts due to the impacts of climate change in the most vulnerable regions. [ABSTRACT FROM AUTHOR]

This study investigates soil phosphorus (P) partitioning and transformations through chemical fractionation and modeling across various land uses to elucidate their impact on P dynamics and the potential for eutrophication. Geo-referenced soils (0–30 cm at various depth intervals) were collected from diverse land uses, including corn, soybean, wheat stubble, modified relay intercropping, corn-soybean with rye under conventional tillage and no-till systems, and sheep pastures, alongside an adjacent forest (control). Processed soils were sequentially extracted to quantify soluble reactive (SRP), exchangeable (EP), Ca and Mg bound (CaMgP), Fe and Al bound (FeAlP), particulate organic (POP), residual (RP), and total P pools. Results showed significant effects of land use and soil depth on extracted P pools. Notably, corn-soybean with rye exhibited a higher SRP accumulation (2.8 mg/kg) compared to the forest. The labile (SRP + EP), moderately labile (FeAlP + CaMgP + POP), and non-labile P (RP) pools accounted for 1 to 2, 23 to 29, and 65 to 76% of total P, respectively. The structural equation model elucidated soil P transformation, indicating the contribution of labile, moderately labile, and non-labile P pools to SRP accumulation in various land uses. Our findings underscore the critical link between land use, soil P dynamics, and eutrophication risk, offering valuable insights for developing agricultural management practices aimed at mitigating edge-of-field P loss and protecting water quality against eutrophication. [ABSTRACT FROM AUTHOR]

In contrast to prolonged exposure to high temperatures, investigating short-term high-temperature stress can provide insights into the impact of varying heat stress durations on plant development and soil nutrient dynamics, which is crucial for advancing ecological agriculture. In this study, five heating temperatures were set at 200°C, 250°C, 300°C, 350°C, and 400°C, along with five heating time gradients of 6s, 10s, 14s, 18s, and 20s, including a control. A total of 26 treatment groups were analyzed, focusing on maize growth parameters and soil indicators. Principal component analysis was used for comprehensive evaluation. The results showed that high-temperature treatments with different heating times significantly influenced maize growth and soil properties. For instance, the treatment of 300°C+6s resulted in the longest total root length, while 200°C+6s led to the highest average root diameter. Plant height and leaf length were notably increased with the treatment of 400°C+6s. Most treatments resulted in decreased soil pH and organic matter content. Notably, the treatment of 350°C+16s showed the highest available phosphorus content, reaching 24.0 mg/kg, an increase of 4.5 mg/kg compared to the control. The study found that the average levels of active organic carbon and peroxidase were 1.26 mg/g and 3.91 mg/g, respectively. Additionally, the average mass fractions of clay, silt, and sand particles were 8.99%, 66.75%, and 24.26%, respectively. Through principal component analysis, six principal components were able to extract 19 indicators from the 26 treatments, covering 86.129% of the information. It was observed that 16 treatment methods performed better than the control in terms of soil comprehensive quality. The optimal treatment temperature and time identified for improving soil physicochemical properties and crop growth were 300°C+6s. These findings can be used to guide agricultural management and soil improvement practices, ultimately enhancing field productivity and providing valuable insights for sustainable agricultural development. [ABSTRACT FROM AUTHOR]

Climate change had widespread and profound impacts on both natural and social ecological systems. Agricultural soil carbon storage, an important component of the terrestrial carbon pool, played a critical role in global climate change, sustainable agricultural development, and global food security. This study conducted a comprehensive literature review to investigate the multi-dimensional effects of climate change on agricultural soil carbon storage and evaluated the advantages, disadvantages, and applicability of various assessment methods for agricultural soil carbon storage. The results showed that the multi-dimensional effects of climate change included both single-factor effects and the combined effects of multiple climatic factors. Single-factor effects included rising temperatures, changes in precipitation patterns, increasing carbon dioxide concentrations, atmospheric nitrogen deposition, and various extreme weather events. These factors individually affected the input, output, and transformation processes of soil carbon in agricultural systems. For example, rising temperatures accelerated the decomposition of soil organic matter, leading to soil carbon loss, while elevated carbon dioxide concentrations enhanced plant photosynthesis, increasing carbon inputs from plant residues to the soil. The combined effects of multiple climatic factors, such as temperature-precipitation, temperature-precipitation-carbon dioxide, and carbon dioxide-nitrogen deposition-ozone, added complexity to understanding the effects of climate change on agricultural soil carbon storage. These interactions could have synergistic or antagonistic effects on soil carbon dynamics, highlighting the need for a comprehensive approach to studying the response of agricultural soil carbon to climate change. Three main categories of methods were identified to assess agricultural soil carbon storage under climate change: statistical analysis models, process-based simulation models, and hybrid models. Statistical analysis models, including linear regression and machine learning models, established relationships between environmental factors and soil carbon storage, revealing the influence of environmental variables on soil carbon. Process-based simulation models could be divided into process-oriented and microbial-oriented models, depending on whether the decomposition of microorganisms was explicitly represented. These models quantitatively described the interactions among climate, vegetation, soil, and other factors and predicted dynamic changes in agricultural soil carbon storage under future climate change scenarios. Hybrid models took advantage of each method to achieve greater simulation accuracy, reliability, and interpretability by combining two or more different types of models. Some common hybrid models included regression kriging model, process-oriented machine learning model, and so on. Finally, four key areas for future research were suggested. First, the soil carbon storage mechanisms driven by microorganisms should be studied in more detail, as they played an important role in soil carbon cycling. Second, the interactive effects of multiple climate change factors should be emphasized to capture the complexity of future climate change scenarios. Third, the development of hybrid models that integrated statistical analysis and process-based simulation was crucial to improve the accuracy and applicability of soil carbon storage assessments. Fourth, uncertainty analysis in model parameters, input data, and scaling methods should be improved to enhance the reliability of model predictions. In conclusion, this study presented a comprehensive climate-crop-soil research framework through systematic integration and analysis, contributing to the scientific understanding of the impact mechanisms of climate change on agricultural soil carbon storage. [ABSTRACT FROM AUTHOR]

The aim of the current study is to provide evidence regarding the influence of particle size on the dynamic properties in granular materials. Experiments using a resonant column (RC) device were conducted on glass beads having similar coefficient of uniformity, but four different mean grain sizes to describe the tendencies in the magnitude of Gmax and Emax. It can be clearly seen that for similar particle gradation the influence of particle size is significant, in particular for larger mean grain sizes d50 exceeding 1·5 mm. The experimental data were fitted using existing empirical relationships with corresponding fitting parameters. The fitting parameters describing the void ratio and pressure dependence to estimate maximum stiffness were found to depend on grain size to a certain extent. This influence was diminished for the materials with a d50 < 1·5 mm. It was therefore possible to use a unique set of fitting parameters for these materials with a satisfying degree of accuracy. The results were compared with some previous studies to highlight the size dependency of Gmax and Emax for materials with mean size greater than 2 mm, but also the relatively small influence on materials with lower mean particle sizes (d50 < 2 mm) is acknowledged. The results are furthermore discussed through a micromechanical interpretation highlighting why larger grain sizes influence stiffness values. [ABSTRACT FROM AUTHOR]

A 2-year field experiment was conducted to test the effects of individual and co-application of biochar and inorganic fertilizer on soil quality using the principal component analysis (PCA) technique. The dry season field experiments were performed with biochar applied at 0 and 20 t ha−1, and fertilizer at 300 and 0 kg ha−1 (control). The factorial combinations of the above-mentioned treatments were subjected to irrigation at 60, 80, and 100% of irrigation amounts (IAs). Soil hydro-physical and chemical properties and grain yield were determined at harvest. Results from the PCA indicated that the soil total nitrogen (N) and moisture content (MC) were the soil properties mostly affecting the grain yield. The amendments' effects on the soil physico-chemical properties and maize yield were in the order control < biochar < fertilizer < biochar + fertilizer. The derived comprehensive soil quality index (CSQI) from the PCA showed that the soil quality increased by 76, 100, and 200% in treatments individually applied with biochar, inorganic fertilizer, and the co-applications. This study therefore showed that the PCA revealed the actual dynamics in soil properties, in terms of the SQI upon the soil amendment addition, as well as their relationship with maize yield under different weather conditions. [ABSTRACT FROM AUTHOR]

Cover crops (CCs) are regarded as beneficial to agricultural practice as an option for soil quality improvement in field production systems. The main goal of this study was to assess the impact of spring phacelia (Phacelia tanacetifolia Benth.) and buckwheat (Fagopyrum Mill.) in a crop rotation (CC–leek–parsley, 2020–2021) on the physicochemical and biological properties of the soil in an organic high tunnel system. Soil analyses involved measurements of bulk density, water capacity, soil aggregation, soil organic carbon (SOC), available soil nutrients, as well as microbial abundance and diversity. Phacelia generated more aboveground biomass (58.2 t fresh matter ha−1) than buckwheat (33.0 t ha−1), and their biomass contained 161 kg N ha−1 and 67 kg N ha−1, respectively. A large quantity of elements, such as N, Ca, P, S, B, and Cu, were found in phacelia biomass. More Mg and Na were found in buckwheat plants. The results showed that CC biomass significantly improved some of the soil physical and chemical properties, such as soil organic carbon stock and wet aggregate stability, and decreased soil bulk density. Cover crop treatments changed the dynamics of soil bacterial and fungus populations in a high tunnel system. Phacelia increased the quantity of ammonifiers and nitrifiers in the soil substantially. Further research with a long-term focus is needed to assess the impact of cover crops on soil properties, soil quality, and subsequent crop yields in high tunnel crop rotation and management systems. [ABSTRACT FROM AUTHOR]

Background and aims: Several lines of evidence indicate that arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) associations can have different effects on soil nutrient dynamics. Some lineages of ECM fungi can extract N from organic matter, with varying impacts on decomposers, soil carbon pools, mineral N availability, and plants that lack ECM. However, these effects are not always observed, and it is not clear how they are mediated by environmental factors. Methods: We used Plant Root Simulator probes to compare soil availability of a wide range of nutrients beneath replicated 30-yr old plantations of Chilean Nothofagus (ECM) and Cupressaceae (Austrocedrus, Fitzroya: AM) on a lowland temperate site. Probes were buried for two 8-week periods in early spring and late summer. We also compared understorey composition beneath plantations, to test for evidence of different successional trajectories beneath Nothofagus and Cupressaceae. Results: Soil organic carbon, total N and total phosphorus did not differ significantly between Nothofagus and Cupressaceae stands. Redundancy analysis revealed significant effects of both plantation type (Nothofagus vs. Cupressaceae) and season on overall mineral nutrient availability. Mineral N availability did not differ significantly between Nothofagus and Cupressaceae plots, but pH and calcium availability were significantly lower beneath Nothofagus. Manganese (Mn) was much more available beneath Nothofagus stands, which might reflect abundant Mn-peroxidase, a key enzyme involved in breakdown of lignin by ECM fungi. Understorey composition varied considerably between individual plantations, but did not differ significantly between Nothofagus and Cupressaceae plantations. Conclusions: Despite an overall effect on the stoichiometry of nutrient availability, we found little evidence of modification of the local N cycle by ECM fungi, or of divergent regeneration patterns beneath AM and ECM plantations. This might reflect the relatively N-rich character of this site, and/or mycorrhizal effects being counteracted by leaf trait differences between Chilean Cupressaceae and Nothofagus species. [ABSTRACT FROM AUTHOR]

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

Aims: Plant and soil nitrogen (N) isotope ratios (δ15N) have been used as indicators of N cycling processes of ecosystems. However, the effects of N and Phosphorus (P) addition on δ15N values and their indicative roles in N-cycling in legume-dominated tropical forests remain poorly understood. Methods: We compared leguminous (Acacia auriculiformis) and non-leguminous (Eucalyptus urophylla) forests in terms of N concentration and δ15N in the leaf–litter–soil continuum under long-term N and P addition. Typical soil N-cycling processes, including rates of mineralization, nitrification, and N loss, were also examined to determine the differences between the corresponding 15N signatures observed in the leguminous and non-leguminous forests. Results: The plants in both tropical forests were found to be 15N-depleted. N addition significantly increased the foliage δ15N in understorey species in the non-leguminous but not the leguminous forest. In both forests, the addition of N resulted in an increase in nitrate (NO3−) leaching and nitrous oxide (N2O) emission. Conversely, P addition led to a decrease in NO3− leaching and N2O emission. Additionally, foliage δ15N was positively correlated with soil N loss rates (N2O emission and NO3− leaching) in the non-leguminous forest but showed no correlation in the leguminous forest. Conclusions: In contrast to the traditional convention derived from non-leguminous forests, our results suggest that foliar 15N isotope signals are not applicable for indicating the soil N dynamic status of leguminous forests. This study highlights the importance of distinguishing legumes from other plant species in terrestrial N-cycling models when incorporating 15N isotope signals. [ABSTRACT FROM AUTHOR]

Background and aims: Forest management practices affect soil carbon dynamics, particularly by changing the diversity of aboveground plant functional groups. However, we have a limited understanding of the underlying mechanisms for how plant management affects soil respiration in planted forest ecosystems. Methods: We conducted a 3-year manipulation experiment of plant functional groups that included understory removal, tree root trenching, and fertilization treatments in 2-year-old and 6-year-old Eucalyptus plantations in the subtropical region, to explore the responses of soil carbon emission and microbial community composition. Results: Soil respiration was significantly suppressed by understory removal (-38%), tree root trenching (-41%), and their interactions (-54%), but fertilization alone and in interactions had no significant effect. Soil bacterial and fungal diversity was negatively affected by understory removal and tree root trenching, respectively. Soil respiration and microbial diversity were lower in younger plantations. Reductions in soil carbon emissions were associated with losses of plant functional groups and soil microbial diversity, while increases in soil respiration were associated with soil physicochemical factors, soil temperature, and plantation age. Conclusions: The results indicated that understory removal and tree root trenching strongly affected soil respiration, while the power effects were regulated by soil microbial community and soil properties in contrast plantation ages. Our findings highlight that plant management is of great significance to the soil carbon emission processes in afforested plantations. [ABSTRACT FROM AUTHOR]

New soil organic carbon (SOC) formation in cropland from straw/stover or manure input is a vital source of SOC for climate change mitigation. However, location and variations in the efficiency, specifically the ratio of new SOC formation to organic C input (NCE), remain unquantified globally. In this study, the spatial variability of cropland NCE from straw/stover or manure input and explanatory factors were determined by analyzing 897 pairs of long‐term field measurements from 404 globally distributed sites and by mapping grid‐level cropland NCEs. The global NCE for paddy and upland averaged 13.8% (8.7%–25.1%, 5th–95th percentile) and 10.9% (6.8%–17.3%), respectively. The initial SOC and the clay content of soil, rather than temperature, were the most important factors regulating NCE. A parabola with an apex at approximately 17 g kg−1 between the initial SOC and NCE was resolved, and a positive correlation between soil clay content and NCE was observed. High‐resolution mapping of the global NCE derived from manure/straw and insight into NCE dynamics provide a benchmark for diagnosing cropland soil C dynamics under climate change and identifying priority regions and actions for C management. [ABSTRACT FROM AUTHOR]

The magnitude of terrestrial carbon (C)‐climate feedback largely depends on the temperature sensitivity of soil organic matter (SOM) decomposition (Q10). However, our understanding of determinants of Q10 for SOM fractions such as particulate and mineral‐associated organic matter (POM and MAOM, respectively) is still inadequate. Particularly, it remains unclear whether microbial effects on Q10 are fraction‐dependent, which induces large uncertainties in projecting soil C dynamics. Here, we conducted large‐scale topsoil sampling on the Tibetan Plateau, in combination with SOM fractionation and 300‐day laboratory incubation to assess SOM fraction‐dependent linkages between Q10 and microbial properties. We found that compared with MAOM, POM had larger Q10 and greater microbial diversity, and also structured distinct microbial communities as well as their co‐occurrence patterns. Furthermore, associations of Q10 with microbial properties differed between the two SOM fractions. Bacterial community composition and relative abundance of bacterial keystone taxa affected Q10 for POM and MAOM respectively, while bacterial alpha diversity showed opposite relationships with Q10 for POM and MAOM. These findings highlight the necessity of incorporating SOM fraction‐dependent microbial properties and their linkages with Q10 into Earth system models to accurately predict terrestrial C‐climate feedback. [ABSTRACT FROM AUTHOR]

Background Aims Methods Results Conclusions The current transformation of the entire energy system leads to a large‐scale expansion of extra‐high‐voltage underground transmission lines (UTL). Knowledge of the impact on soil temperature and soil moisture dynamics is fundamental for environmental evaluation.We investigated the impact of an existing 320 kV underground cable in continuous operation on soil temperature and moisture dynamics.A soil‐monitoring programme was established at four study sites in Western Germany. Data were continuously recorded in soil up to 120 cm depth using soil sensors over a period of 1 year.Soil warming was in a range of 0.6 K in the topsoil, approx. 1–1.3 K in the rooting zone and 1.7 K in the subsoil at 120 cm depth and was restricted mainly to the immediate vicinity of the cable route. Likewise, the impact on soil moisture dynamics was on average in a range of −1.00 wt.‐% in 0–60 cm depth and −2.45 wt. 2‐% in the subsoil relative to control. Although at a calculated maximum load capacity of 100% in regular operation, soil warming might remain moderate, with 1.5 K in the topsoil, 2.3–3.1 K in the rooting zone and 4.1 K in the subsoil.It is assumed that the reasons for the low‐to‐moderate influence of the UTL are to be found in the operational cable load (on average 65%), heat loss of cables (approx. 12 W m−1 per cable) and the quality of the imbedding material for the cables. [ABSTRACT FROM AUTHOR]

In recent years, machine learning (ML) algorithms have gained substantial recognition for ecological modeling across various temporal and spatial scales. However, little evaluation has been conducted for the prediction of soil organic carbon (SOC) on small data sets commonly inherent to long-term soil ecological research. In this context, the performance of ML algorithms for SOC prediction has never been tested against traditional process-based modeling approaches. Here, we compare ML algorithms, calibrated and uncalibrated process-based models as well as multiple ensembles on their performance in predicting SOC using data from five long-term experimental sites (comprising 256 independent data points) in Austria. Using all available data, the ML-based approaches using Random forest and Support vector machines with a polynomial kernel were superior to all process-based models. However, the ML algorithms performed similar or worse when the number of training samples was reduced or when a leave-one-site-out cross validation was applied. This emphasizes that the performance of ML algorithms is strongly dependent on the data-size related quality of learning information following the well-known curse of dimensionality phenomenon, while the accuracy of process-based models significantly relies on proper calibration and combination of different modeling approaches. Our study thus suggests a superiority of ML-based SOC prediction at scales where larger datasets are available, while process-based models are superior tools when targeting the exploration of underlying biophysical and biochemical mechanisms of SOC dynamics in soils. Therefore, we recommend applying ensembles of ML algorithms with process-based models to combine advantages inherent to both approaches. • We evaluated process-based (PB) and machine-learning (ML) models for SOC prediction. • Random forest & support vector machine predicted SOC superior to PB models. • Reduced data availability and quality significantly weakened ML model performance. • ML-assisted PB model ensembles strongly improved model performance. [ABSTRACT FROM AUTHOR]

Assessment of the current state of the near-surface part of the geological environment and understanding of its layered structure play an important role in various scientific and applied fields. The presented work is devoted to the application of phasometric modifications of geoelectric control methods to solve the problem of the detailed complex study of the underground layers of the environment in the process of drilling operations with the use of special equipment. These studies are based on the analysis of variations in phase parameters and characteristics of an artificially excited multiphase electric field to assess poorly distinguishable details and changes in the layered structure of the medium. The proposed method has increased accuracy, sensitivity and noise proofness of measurements, which allows for extracting detailed information about the heterogeneity, composition and stratification of underground geological formations not only in the zone where the drill makes contact with the medium, but also in the entire control zone. This paper considers practical mathematical models of phase images for basic scenarios of drill penetration between the layers of the near-surface part of the geological medium with different characteristics, obtained by means of approximation apparatus based on continuous piecewise linear functions, and also suggests the use of modern machine learning methods for intelligent analysis of its structure. Studying the phase shifts in electrical signals during drilling highlights their value for understanding the dynamics of soil response to the process. The observed signal changes during the drilling cycle reveal in detail the heterogeneity in soil structure and its response to changes caused by drilling. The stability of phase shifts at the last stages of the process indicates a quasi-equilibrium state. The results make a significant contribution to geotechnical science by offering an improved approach to monitoring a layered structure without the need for deep drilling. [ABSTRACT FROM AUTHOR]

Rhizodeposition fuels carbon (C) and nutrient cycling in soil. However, changes in the dynamics of microbial growth on rhizodeposits with increasing distance from the root is not well studied. This study investigates microbial growth on individual organic components of rhizodeposits and maize root‐derived exudates and mucilage from agricultural soil. By creating a gradient of substrate concentrations, we simulated reduced microbial access to rhizosphere C with increasing distance to the root surface. We identified distinct C‐thresholds for the activation of microbial growth, and these were significantly higher for rhizodeposits than singular, simple sugars. In addition, testing for stoichiometric constraints of microbial growth by supplementing nitrogen (N) and phosphorus (P) showed accelerated and increased microbial growth by activating a larger proportion of the microbial biomass. Early and late season exudates triggered significantly different microbial growth responses. The mineralization of early‐season exudates was induced at a high C‐threshold. In contrast, the mineralization of late‐season exudates showed 'sugar‐like' properties, with a low C‐threshold, high substrate affinity, and a reduced maximum respiration rate of microorganisms growing on the added substrate. Mucilage exhibited the highest C‐threshold for the activation of microbial growth, although with a short lag‐period and with an efficient mucilage degradation comparable to that of sugars. By determining kinetic parameters and turnover times for different root‐derived substrates, our data enable the upscaling of micro‐scale processes to the whole root system, allowing more accurate predictions of how rhizodeposition drives microbial C and nutrient dynamics in the soil. [ABSTRACT FROM AUTHOR]

Knowledge regarding soil wetness dynamics is relevant for its application in hydrological and climatological studies. It is also a parameter that allows the analysis of processes related to land cover and land use. Due to this importance, the spatio-temporal dynamics of the surface soil humidity (SSH) in the southern of the Argentinean Pampean Plains have been analyzed, based on data corresponding to six Argentine localities and in relation to a climatological index that incorporates rainfall and evapotranspiration variables. The methodology includes statistical correlation and multivariate analysis based on modeled and reanalysis data. The results obtained reveal a different response of the SSH at a spatial level, with maximum values in the highest rainfall region, diminishing towards the most arid zone. This allows us to infer the influence of the topographic homogeneity of the area and the predominance of vertical processes in the hydrological balance. At both a spatial and temporal scale, the SSH dynamics concur with the climatological index pattern, confirmed by a Pearson coefficient. It has also been shown that the SSH responds to the climatological parameters and that the highest correlation occurs at a three-month temporal scale. This response may be observed at an interannual and annual level, with maximum and minimum values during the wet and dry years, respectively and a decrease in the SSH during the warmest seasons (summer). The SSH displays the same tendency as the climatological index, from NE to SW, reaching a maximum in the rainiest area and minimum in the arid region. The manuscript, based on diverse sources analysis, pluviometric periods classification and statistical methods application, is a contribution related to the edaphic variable dynamics in a region in which farming activity constitutes the main land use and where the droughts and floods alternance has effects on the flooding risks and the economic losses as a consequence of intensive droughts, respectively. [ABSTRACT FROM AUTHOR]

Phosphorus is one of the major constraints to karst grassland productivity. Understanding the effects of different fertilization practices on soil phosphorus dynamics is essential for enhancing phosphorus bioavailability and rational management of soil phosphorus in karst grasslands. Here, we investigated the effects of fertilizers and manures on soil bioavailability of phosphorus fractions and explored the relationship between soil properties and soil phosphorus fractions. The four fertilizer application designs were as follows: control (CK; no fertilizer or manure); fertilization (F); manure application (M); fertilization and manure application (FM). The results showed that total phosphorus (TP) concentration was elevated by 23%, 1%, and 42% in F, M, and FM treatments, respectively, compared with CK. F and FM treatments enhanced the total inorganic phosphorus (Pi) concentration by 65% and 66%, respectively, while M and FM treatments enhanced the total organo-phosphorus (Po) concentration by 21% and 35%, respectively. FM treatment elevated bioavailable P, active Po, secondary mineral P, primary mineral P, and occluded P by 69%, 39%, 50%, 31%, and 41%, respectively. Fertilizers inhibited soil acid phosphatase activity, whereas alkaline phosphatase did not respond significantly to fertilizer management in low-latitude karst regions. SOM, TN, AP, and MBP are the key factors affecting the bioavailability of phosphorus fractions. The combined application of fertilizer and manure is the most beneficial measure for enhancing soil phosphorus bioavailability. This research helps deepen our understanding of soil phosphorus dynamics in the karst areas and provides a basis for further enhancement of nutrient availability and vegetation productivity of grassland ecosystems. [ABSTRACT FROM AUTHOR]

Phosphorus (P) dynamics in the soil subsurface are relatively unstudied, especially in forest soils, and may be important in areas with groundwater‐fed surface water bodies. Here, we use X‐ray absorption near‐edge P spectroscopy (P‐XANES) and X‐ray fluorescence microprobe mapping (µ‐XRF) to examine P speciation and co‐localization with Fe and Al as a function of depth in soils from coniferous and deciduous forests. P‐XANES revealed similar trends in P speciation with depth for both forest types, with Al‐P and Fe‐P being dominant, whereas Ca‐P and organic P were minor constituents. Correlation plots derived from µ‐XRF mapping revealed a strong correlation between P and both Fe and Al at all depths. At depths of up to 378 cm, a range that includes A, E, and B horizons, the relationships between P and Al/Fe were remarkably consistent, consisting of a population of P diffusely associated with Al/Fe, consistent with Fe‐ or Al‐adsorbed P, as well as P linearly correlated with Al/Fe in several discreet groupings, indicative of the presence of specific P compounds. At depths below 378 cm, the relationships between P and Al/Fe changed dramatically, with correlation plotting indicating the disappearance of any diffuse P:Al/Fe relationships. This change occurred concurrently with a decrease in oxalate extractable P, suggesting that the P present in this deep soil horizon may be present in a more stable form that is less available for transport, as well as potentially indicating that P adsorbed to Fe/Al did not readily pass through the overlaying Bw soil horizon. Core Ideas: Organic P and Ca‐P minor constituents of overall P pool, which was dominated by Al‐P and Fe‐P.Similar trends in deciduous/coniferous soils, suggesting litter composition unimportant at these study sites.Correlation plotting revealed consistent P:Al/Fe relationships from surface down to 378 cm (Bw horizon). [ABSTRACT FROM AUTHOR]

Background and aims: The accumulation of soil organic carbon (SOC) is a crucial process in mitigating climate change and ensuring soil quality. Subtropical plantations in China have shown high potential for enhancing SOC sequestration due to their high carbon sink capacity. However, the dynamics and compositions of SOC after long term afforestation are still poorly understood. Methods: We examined the dynamics of SOC and its fractions of different soil layers (0–5 cm, 5–10 cm, 10–20 cm, 20–40 cm, 40–80 cm, 80–100 cm) in a mixed broadleaf-conifer plantation (BCP), a Masson pine plantation (MP), and a Slash pine plantation (SP), and an enclosed forest (EF) in subtropical China. Both physical fractions (particulate organic carbon (POC), soil clay organic carbon (SOCclay), soil silt organic carbon (SOCsilt)) and chemical fractions (iron-aluminum-bound organic carbon (Fe/Al-OC), and calcium-bound organic carbon (Ca-OC)) were determined. Additionally, soil physicochemical properties were further analyzed. Results: Our results showed the SOC storage in the EF, BCP, MP, and SP in 2019 increased by 82%, 238%, 126%, and 103% respectively compared to 1984. The proportions of MAOC to SOC were respectively as follows: SP (65.9%) > BCP (64.9%) > EF (61.6%) > MP (53.9%). The mean proportions of SOCclay to MAOC were as follows: BCP (71.1%) > EF (66.9%) > MP (58.5%) > SP (51.0%). The mean proportions of Fe/Al-OC to MAOC were as follows: EF (53.3%) > SP (48.3%) > MP (47.9%) > BCP (39.8%). All these proportion increased with soil depth. RDA and PLS-SEM analysis revealed that soil nitrogen content and electrochemical properties (pH and EC) were the main factors that controlled SOC content and fractions. Conclusions: Subtropical plantations have significant soil carbon sequestration capabilities, but they are currently nearing saturation. Soil nitrogen content may be key factor limiting further enhancement of carbon sequestration. Due to the high proportion of MAOC and relative consistent SOC storage, BCP and SP are recommended as priorities for plantation regeneration in subtropical China. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) are prevalent emerging pollutants in soil environments, acting as carriers for other contaminants and facilitating combined pollution along with toxic metals like cadmium (Cd). This interaction increases toxic effects and poses substantial threats to ecosystems and human health. The objective of this study was to investigate the hydrodynamic adsorption of Cd by conducting experiments where polystyrene microplastics (PS) and biochar (BC) coexisted across various particle sizes (10 µm, 20 µm, and 30 µm). Then, soil incubation experiments were set up under conditions of combined pollution, involving various concentrations (0.5 g·kg−1, 5 g·kg−1, 50 g·kg−1) and particle sizes of PS and BC to assess their synergistic effects on the soil environment. The results suggest that the pseudo-second-order kinetic model (R2 = 0.8642) provides a better description of the adsorption dynamics of Cd by PS and BC compared to the pseudo-first-order kinetic model (R2 = 0.7711), with an adsorption saturation time of 400 min. The Cd adsorption process in the presence of PS and BC is more accurately modeled using the Freundlich isotherm (R2 > 0.98), indicating the predominance of multilayer physical adsorption. The coexistence of 10 µm and 20 µm PS particles with BC enhanced Cd absorption, while 30 µm PS particles had an inhibitory effect. In soil incubation experiments, variations in PS particle size increased the exchangeable Cd speciation by 99.52% and decreased the residual speciation by 18.59%. The addition of microplastics notably impacted the exchangeable Cd speciation (p < 0.05), with smaller PS particles leading to more significant increases in the exchangeable content—showing respective increments of 45.90%, 106.96%, and 145.69%. This study contributes to a deeper understanding of the mitigation mechanisms of biochar in the face of combined pollution from microplastics and heavy metals, offering theoretical support and valuable insights for managing such contamination scenarios. [ABSTRACT FROM AUTHOR]

The ecologically and economically vital symbiosis between nitrogen-fixing rhizobia and leguminous plants is often thought of as a bi-partite interaction, yet studies increasingly show the prevalence of non-rhizobial endophytes (NREs) that occupy nodules alongside rhizobia. Yet, what impact these NREs have on plant or rhizobium fitness remains unclear. Here, we investigated four NRE strains found to naturally co-occupy nodules of the legume Medicago truncatula alongside Sinorhizobium meliloti in native soils. Our objectives were to (1) examine the direct and indirect effects of NREs on M. truncatula and S. meliloti fitness, and (2) determine whether NREs can re-colonize root and nodule tissues upon reinoculation. We identified one NRE strain (522) as a novel Paenibacillus species, another strain (717A) as a novel Bacillus species, and the other two (702A and 733B) as novel Pseudomonas species. Additionally, we found that two NREs (Bacillus 717A and Pseudomonas 733B) reduced the fitness benefits obtained from symbiosis for both partners, while the other two (522, 702A) had little effect. Lastly, we found that NREs were able to co-infect host tissues alongside S. meliloti. This study demonstrates that variation of NREs present in natural populations must be considered to better understand legume–rhizobium dynamics in soil communities. [ABSTRACT FROM AUTHOR]

Biofertilizers, consisting of carefully selected microorganisms across various species and genera, exhibit distinct features that enhance soil fertility and promote plant growth. Embracing the principles of eco-friendly agriculture, the use of biofertilizers emerges as a pivotal strategy for sustainable farming, contributing to environmental preservation and the overall health and biodiversity of the soil. In this study, a commercially available biofertilizer, containing a specialized strain of Priestia megatherium with nitrogen-fixing capabilities, was employed alongside chemical fertilizers at two different doses (30 and 40 mg per kg of soil). The primary objective was to evaluate the impact of biofertilizer on the metabolic activity and structure of microbial communities in a short-term experiment involving potted maize plants, utilizing the BIOLOG® EcoPlates technique. Parameters such as average well-color development (AWCD) and substrate utilization across six guilds (SAWCD) were assessed to gauge microbial metabolic activity. Additionally, functional indexes, including Shannon diversity, Shannon evenness, and Simpson diversity, were calculated as indicators of soil microbial community functionality. While statistically significant differences in AWCD among the studied variants were not observed, all estimated functional indexes consistently revealed heightened microbial diversity and evenness following the application of biofertilizer. This noteworthy finding, achieved within a relatively short period of plant cultivation, underscores the necessity for further research to explore the biofertilizer's enduring effects on soil communities, both in controlled laboratory environments and under real-world field conditions. [ABSTRACT FROM AUTHOR]

The designer of irrigation systems must consider a complex combination of emitter type, emitter uniformity, hydraulics, topography, desired water distribution, crop salt tolerance, water requirements, water quality, fertilizer injection, soil salinity, cultural practices, and other site-specific conditions. In contrast to the approaches applied for the hydraulic design of irrigation installations, there is not a clear, general and consolidated design criterion for calculating the number required emitters per plant. In most cases, given the wide spectrum of possible scenarios, only guideline recommendations can be found, and the final decision is often based on the subjective experience of the designer or grower. This paper aims at revising, clarifying and refining the existing published guidelines and methodologies for estimating the required emitters per plant in drip irrigation, focussing on the Montalvo approach. The agronomic design should satisfy, among others, two specific conditions: (i) the emitters should wet at least a minimum threshold of the soil area (or volume) corresponding to the plant for ensuring a proper development of the roots; (ii) overlapping between emitter bulbs is required for merging wetted volumes and avoiding salt concentration near the root zone. Relying on this basis, a thorough theoretical geometric analysis of the overlapping between wet bulbs of contiguous emitters is carried out. As a result, Montalvo's overlapping coefficients are deduced here. This author assumes an identical net wetted area for all emitters in the laterals, but it can be stated that the overlapping areas between emitters differ in extreme emitters and interior emitters, as well as in configurations with one lateral per plant row and two laterals per plant row. Therefore, this study proposes new formulations for the computation of the overlapping coefficient, which need to incorporate the number of emitters as an additional variable, as well as to distinguish between the presence of one or two laterals per plant row, and between grouped and non-grouped emitters. In one lateral per plant row, the original overlapping coefficient underestimates the net wetted area by one emitter and thus overestimates the theoretical number of required emitters. In the case of two laterals per plant row, the original overlapping coefficient overestimates the net wetted area in the interior emitters, and thus underestimates the theoretical number of required emitters per plant. The presented formulations are applied in different practical examples covering a wide range of scenarios. The results allow a general overview of the influence of the soil type, the emitter flow rate, and the selected overlapping ratio in the number of required emitters per plant. The revision of guidelines and methods presented here, complemented with other experimental results and models of soil water dynamics under drip irrigation, might contribute to a better decision making of designers and field engineers. [ABSTRACT FROM AUTHOR]