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Microarthropods such as mites (Acari) and springtails (Collembola) play a key role in the functioning of nutrient‐poor ecosystems. They contribute to the comminution of organic matter and they are likely to affect the structure and function of soil microbial communities through grazing and by changing substrate availability. However, the precise effects of their interactions with microbiota remain poorly understood. In the present study, we conducted a mesocosm field experiment to determine the effects of soil microarthropod density on community composition of soil fungi. We manipulated microarthropod densities in 100 defaunated and soil‐filled meshed mesocosms by inoculating half of the units with microarthropods (i.e. high‐density treatment), while the other half of the units only contained few specimens possibly hatching from recalcitrant eggs that survived defaunation (i.e. low‐density treatment). All mesocosms were then inserted in the top soil of a range of nutrient‐poor grasslands and heathlands in Belgium for the duration of three months. The entire mesocosms were composed of mesh (30 μm mesh size) to allow for a rapid (re‐)colonization by microbes from the surrounding soils, while migration of microarthropods in or out of the mesocosms was precluded. Litter bags (30 μm mesh size) containing two types of organic matter were also buried within each mesocosm, and organic matter mass loss over time was used as a proxy to assess effects of microarthropod density on microbe‐regulated decomposition rates. We found that fungal community composition differed strongly between the two microarthropod density treatments, regardless of habitat type. The mesocosms with higher microarthropod densities were characterized by a higher number of fungal OTUs and a higher number of fungal indicator species associated to this treatment. Microarthropod density, however, did not affect microbe‐regulated organic matter decomposition rates, nor did it affect relative abundances of putative fungal functional groups, thus suggesting considerable levels of fungal functional overlap. Synthesis. The lack of measurable changes in organic matter decomposition or shifts in fungal functional group representation suggest that effects of microarthropods on the functioning of fungal communities may be lower than originally thought. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

This study investigates the effects of physical and chemical soil degradation on crop productivity in the Korekore Watershed. The watershed was categorized into level, sloping, and steep slope gradients. Within each slope gradient, one cultivated land managed with soil and water conservation and one cultivated land without soil and water conservation were selected. Selected soil physicochemical analyses were performed on 18 disturbed and undisturbed soil samples and were taken from the top 0–20 cm depths from each cultivated land with three replications. The soil degradation index (SDI) was evaluated based on the percent changes in soil properties of cultivated land without soil and water conservation to that of the cultivated land managed with soil and water conservation. The crop productivity index was determined by analyzing the percentage growth rate and its standard deviation. Soil bulk density and moisture content improved undercultivated land managed with SWC practices. Significantly higher (p ≤ 0.05) soil organic carbon (SOC) content (2.02%), total N (0.12%), available P (4.69 ppm), and exchangeable K (1.33 cmolc/kg) were observed in cultivated land managed with SWC as compared to cultivated land without SWC measures. The value of the SDI (+243.9%) for the watershed has demonstrated that soil degradation has improved and soil and water conservation measures had a significant impact on crop yields. The average crop yield rate (CYR) (30%) was found to be lower than the estimate provided by the central statistics agency in Ethiopia. A higher CYR was observed in cultivated land managed with soil and water conservation practices. It can be concluded that physical and chemical soil degradation significantly impacts crops unless counterbalanced by soil and water conservation measures. Therefore, it is recommended to implement well‐integrated watershed management practices to improve soil quality and enhance crop productivity. [ABSTRACT FROM AUTHOR]

ABSTRACT During the process of treating soft soil foundations with prefabricated drainage drains (PVD), “soil columns” form around the PVD, and a “weak zone” forms outside the range of the “soil columns.” The difference in properties between the two forms a distinct interface, leading to a gradual decrease in drainage efficiency and obstruction of vertical drainage channels, which in turn causes cracks and lateral displacement in the soil during consolidation. The interfaces between adjacent soil layers are incomplete contact, and the water within the interstices impedes the transfer of heat, manifesting a thermal resistance effect. To address this phenomenon, a synchronous measurement system for the thermal gradient and the heat flux density between the soil interfaces has been developed. Applying Fourier's law of heat conduction, the thermal resistance coefficient has been determined. Based on the theory of thermo‐hydro‐mechanical coupling, a multi‐zone axisymmetric model for saturated soils that considers thermal resistance effect has been proposed. Semi‐analytical solutions were derived and validated through comparison with the custom FEM model and field experiments. The thermal consolidation characteristics of the multi‐zone soils under various thermal contact models have also been discussed, with a comprehensive analysis of the influence of different parameters. Outcomes show that: the generalized incomplete thermal contact model provides a better description of the thermal resistance phenomenon between multi‐zone soils interfaces; ignoring the thermal resistance effect leads to an overestimation of the deformation during the thermal consolidation, and, the thermal resistance effect decreases the influence of the thermo‐osmosis effect on the consolidation characteristics. [ABSTRACT FROM AUTHOR]

The current soil carbon paradigm puts particulate organic carbon (POC) as one of the major components of soil organic carbon worldwide, highlighting its pivotal role in carbon mitigation. In this study, we compiled a global dataset of 3418 data points of POC concentration in soils and applied empirical modeling and machine learning algorithms to investigate the spatial variation in POC concentration and its controls. The global POC concentration in topsoil (0–30 cm) is estimated as 3.02 g C/kg dry soil, exhibiting a declining trend from polar regions to the equator. Boreal forests contain the highest POC concentration, averaging at 4.58 g C/kg dry soil, whereas savannas exhibit the lowest at 1.41 g C/kg dry soil. We developed a global map of soil POC density in soil profiles of 0‐30 cm and 0–100 cm with an empirical model. The global stock of POC is 158.15 Pg C for 0–30 cm and 222.75 Pg C for 0–100 cm soil profiles with a substantial spatial variation. Analysis with a machine learning algorithm concluded the predominate controls of edaphic factors (i.e., bulk density and soil C content) on POC concentration across biomes. However, the secondary controls vary among biomes, with solid climate controls in grassland, pasture, and shrubland, while strong vegetation controls in forests. The biome‐level estimates and maps of POC density provide a benchmark for modeling C fractions in soils; the various controls on POC suggest incorporating biological and physiochemical mechanisms in soil C models to assess and forecast the soil POC dynamics in response to global change. [ABSTRACT FROM AUTHOR]

Verticillium wilt of pistachio (Pistacia vera), caused by Verticillium dahliae, is one of the most important diseases in this crop. The most effective and economical control measure is the use of resistant rootstocks. The main objective of this work was to evaluate the resistance of five rootstocks commonly used in pistachio against the disease under field conditions. Pistachio plants (cv. Kerman) grafted on the rootstocks Pistacia atlantica, Pistacia integerrima, Pistacia terebinthus and cv. Platinum and UCBI hybrids, were planted in a field with high inoculum density of V. dahliae in the soil. Plants grafted on P. terebinthus, followed by P. integerrima, showed significantly higher disease severity values than the rest of the rootstocks almost 53 months after planting; also, plants grafted on P. atlantica were more resistant than those grafted on P. integerrima. These results highlighted the intraspecific variability in resistance to the disease. In addition, the disease was monitored in pistachios grafted onto P. terebinthus or UCBI in an established commercial field with three different zones of V. dahliae inoculum density in the soil (none, low or high). In the high‐density zone, the percentage of diseased plants was significantly lower for plants grafted on UCBI than for those grafted on P. terebinthus. The results indicate the importance of rootstock species and specific genotype or seed population used, concentration of V. dahliae inoculum in the soil, and previous history of crops on the plot, on the development of the disease under natural conditions. [ABSTRACT FROM AUTHOR]

Coastal wetlands are one of the most productive ecosystems on Earth with the capacity to sequester large amounts of carbon dioxide (CO2). Wetland loss due to anthropogenic and natural causes reduces the carbon (C) storage capacity and potentially releases previously fixed C in biomass and soil to the water column and atmosphere through decomposition. Coastal wetland restoration has the potential to mitigate some of the C losses depending on the balance of C fluxes. However, the role of vegetation and environmental conditions in governing rates of C accumulation in restoration sites is not well resolved. The purpose of this study was to examine seasonal C fluxes, specifically, gross ecosystem productivity (GEP), ecosystem respiration (ER), and net ecosystem exchange (NEE) of CO2 in unvegetated and vegetated (Spartina alterniflora) areas of a 2‐year old created marsh, and S. alterniflora and Spartina patens communities in a "natural" reference brackish marsh. S. alterniflora‐dominated areas were sinks for CO2 in both the newly created and reference marsh with an average CO2 uptake rate of 7.0 ± 1.0 μmol m−2 s−1. The unvegetated areas in the newly created marsh and S. patens areas in the reference marsh had approximately net neutral CO2 fluxes. S. alterniflora areas of the created marsh had similar carbon fluxes to that in the reference marsh, despite a much lower soil organic matter content. Because vegetation develops much faster than soil properties, restored marshes can be a C sink equivalent to natural marshes as soon as the marsh is vegetated. Ecosystem productivity and C assimilation in S. alterniflora areas of the reference marsh were enhanced by lower elevations (up to 6 cm) and higher soil bulk density (up to 0.28 g cm−3). At similar elevations, S. alterniflora in both the created and reference marshes was a greater C sink than S. patens areas of the reference marsh. Our findings illustrate that establishment of vegetation is critical to promoting C sink functions in created marshes and, notably, species do matter. [ABSTRACT FROM AUTHOR]

Spectral induced polarization (SIP) exhibits potential to be a nonintrusive approach to monitor bacterial activity in biological hotspots associated with the critical zone of the earth. The polarization of bacteria in a low‐frequency electrical field is related to the polarization of their electrical double layer coating their surface. However, few studies have quantified the induced polarization responses on both gram‐negative (GN) and gram‐positive (GP) bacteria in soil column experiments. To address this gap, 17 experiments using two strains, Pseudomonas aeruginosa O1 (PAO1, GN) and Brevibacillus centrosporus (L3, GP) are conducted. Complex conductivity spectra are collected in the frequency range 10 mHz–10 kHz during bacterial growth and decay phases in soils. The complex conductivity spectra are fitted using a double Cole‐Cole model to remove the effect of Maxwell‐Wagner polarization. The change in the magnitude of the polarization (quadrature conductivity or normalized chargeability of the low‐frequency contribution) is linearly related to the bacterial density, regardless of the type of bacteria. The changes in the normalized chargeability and Cole‐Cole relaxation time are directly proportional to the density of bacteria. Furthermore, it is inferred that the thickness of microcolonies plays a critical role in the relaxation time rather than the diameter of individual bacteria. This study expands the potential of SIP for in situ monitoring of microbial activity in soils. Plain Language Summary: Microorganisms are ubiquitous in the environment. Understanding their impact on the critical zone is crucial in the context of climate change. Spectral induced polarization is a geophysical method that has been proven to be sensitive to the presence of bacteria in porous media, but no specific works have been done for both gram‐negative and gram‐positive bacteria in soils. Column reactor experiments are conducted using the same soil, inoculated with either gram‐negative or gram‐positive strains. Experimental results indicate a direct proportionality between the magnitude of the low‐frequency electrical polarization of the soil and the density of bacteria. It is inferred that the size of microcolonies plays a critical role in the value of the relaxation time. This study provides new quantitative insights into the relationship between the electrical properties and bacterial activity in soils with applications to the nonintrusive monitoring of biological hotspots in the critical zone of the earth. Key Points: The growth and decay of gram‐positive and gram‐negative bacteria in soils exhibit a clear signature on their complex conductivity spectra.The spectra are fitted by a double Cole‐Cole model, and the Maxwell‐Wagner polarization is removed.The normalized chargeability and the Cole‐Cole relaxation time vary linearly with the density of bacteria in the soil. [ABSTRACT FROM AUTHOR]

The additive mass method (AMM) is applied to test the compaction density of soil–rock mixtures (S–RMs) due to its high efficiency, nondestructiveness and accuracy. However, there is no systematic research on influence factor of AMM. In this study, AMM test parameters were systematically calibrated first, and a calculation model for the compaction density of S–RM was established in the test area. After that, the AMM was applied in the on‐site detection of the compaction density of an earth–rockfill dam. After calibration test, the main geophone frequency was 40 Hz, the drop distance and offset distance were 20 and 70 cm, respectively, and set the ∆m of five levels as 38, 88, 138, 213, and 288 kg. The detection error of K–K/ρ model had a better precision than the ω−2−ω−2/ρ model through on‐site testing and verification. A new calculation model with lower accuracy based on vibration stiffness–vibration stiffness/density K−K/ρ) model was proposed according to the test error distribution. It was found that the test error of the K−K/ρ model was reduced to 0.9%. The results demonstrated that the AMM could accurately detect the compaction density of S–RM after the test parameters were reasonably determined. [ABSTRACT FROM AUTHOR]

The effects of reseeded native Gramineae and Leguminosae species on the multifunctionality of desert steppe have remained unclear. Therefore, we examined a semiarid desert steppe that was reseeded 5 years earlier with a dominant native Gramineae species, Agropyron mongolicum; a dominant native Leguminosae species, Lespedeza potaninii; and a 1:1 reseeded mixture of A. mongolicum × L. potaninii. We evaluated the changes in plant communities and soil properties and then quantified aboveground ecosystem multifunctionality (AEMF), belowground ecosystem multifunctionality (BEMF), and overall ecosystem multifunctionality (EMF) using an averaging approach. Compared with the native steppe without reseeding, both reseeded A. mongolicum and A. mongolicum × L. potaninii increased fine root volume, plant height, plant cover, aboveground biomass (AGB), belowground biomass (BGB), soil water storage (SWS), soil organic carbon, light fraction organic carbon, labile organic carbon, total nitrogen (TN), nitrate nitrogen, and total phosphorus (P), but decreased soil bulk density. However, reseeded L. potaninii increased coarse root volume, plant height, plant cover, AGB, BGB, and SWS but decreased plant richness, plant diversity, TN, and total P. In addition, reseeded A. mongolicum and A. mongolicum × L. potaninii increased AEMF, BEMF, and overall EMF, but reseeded L. potaninii only increased AEMF. Further analysis indicated that the fine roots played a crucial role in improving individual ecosystem functions and eventually in determining EMF. Therefore, the reseeding of a desert steppe with Gramineae species has greater potential than with Leguminosae species for improving EMF, since Gramineae species have greater fine roots volume than Leguminosae species. [ABSTRACT FROM AUTHOR]

Understanding the underlying temporal dynamics influencing invasive plant control outcomes is essential to achieve restoration and land management goals. Within grasslands, herbicides are commonly used as the main method for invasive plant control, but the efficacy of management may be dependent on seasonal dynamics, as well as the number of applications. Additionally, assessments to quantify invasive plant control are often limited to aboveground plant composition, overlooking the potential repository of propagules stored in the soil seedbank, and additional impacts on nontarget species. To ensure that an herbicide method is effectively controlling invader populations, while limiting impacts on the resident plant communities, both above‐ and belowground species responses must be assessed. We established an herbicide field experiment across different sites and years in Riverside, CA, U.S.A., to assess the control of a global annual invasive forb, Oncosiphon pilulifer. We investigated how seasonal herbicide management (early‐season vs. late‐season) and repeated annual herbicide applications (1 vs. 2 years) influenced cover and seedbank density of our focal invader and the resident plant community 1 year after treatment. We found that although late‐ and early‐season‐applied herbicides reduced invader cover, early‐season applications were the only strategy to reduce invader seedbank density, indicating potential longer term management control. Lastly, native cover was limited in post‐treated areas, suggesting that additional management strategies may be needed to overcome native establishment limitations in invaded grasslands. [ABSTRACT FROM AUTHOR]

The importance of fine‐root diameter for ecosystem functioning is increasingly recognized, yet much remains to be learned about the variation in fine‐root diameter at large scales. We conducted an analysis of fine‐root diameter for five root orders for 1163 plant species to detect patterns in relation to resource availability (e.g. carbon, nitrogen, water and net primary production (NPP)), stress intensity (e.g. plant/soil biodiversity and soil bulk density) and temperature. First‐ to fourth‐order root diameters showed non‐linear relationships with mean annual temperature (except for first‐order root diameter) and/or with latitude. The diameters of the five root orders decreased with increasing mean annual precipitation, but increased with greater NPP, which was the strongest determinant of fine‐root diameter. Increasing soil biodiversity was associated with decreasing diameters of fourth‐ and fifth‐order roots, while greater plant biodiversity was associated with decreasing diameters of first‐ to third‐order roots. Soil total nitrogen concentration had a positive effect on first‐order root diameter but a negative effect on fourth‐ and fifth‐order root diameters. The patterns reversed for soil total phosphorus concentration. First‐ to third‐order and fifth‐order root diameters increased with greater soil bulk density. Second‐ to fourth‐order root diameters increased with higher soil pH. Overall, the variables related to climatic, biological and edaphic factors explained 44–63% of the total variance in the diameters of the different root orders. The unique patterns of plasticity observed in fine‐root diameter across root orders in response to varying environmental conditions contributes to a diversification of plant strategies for nutrient/water acquisition and transport under climate change. [ABSTRACT FROM AUTHOR]

Drainage density is a fundamental landscape feature that determines the length scale for hillslope sediment transport and results from the competition of diffusive hillslope and advective stream incision processes, whose efficiencies are known to vary with rock type but are notoriously difficult to quantify. Here, we present a comprehensive analysis of a catchment in semi‐arid Central Chile, where landscapes with different drainage densities, but equal tectonic and climatic conditions, have formed on three neighboring granitoid plutons (a monzogranite and two diorites). We combined topographic analysis of a 1‐m digital elevation model with 10Be‐derived denudation rates to estimate stream erosivity and soil diffusivity in the different landscapes. We find that the higher drainage density in the monzogranite is primarily due to higher stream erosivity, whereas soil diffusivity is similar between rock types. Remote sensing data from Landsat imagery confirm field observations of higher vegetation cover in the diorites, especially with regard to deeper‐rooted shrubs, which may result in increased infiltration. Based on geochemical and compositional analyses, we link vegetation differences to a relatively higher abundance of plant‐essential elements in the diorite bedrock. Additionally, the monzogranite's composition and crystal grain size supports more intense physical weathering and leads to a smaller observed hillslope grain size, which increases its erodibility. We conclude that subtle differences in composition and grain size can have a significant impact on stream erosivity and drainage density. Our results demonstrate the importance of taking lithology into account when interpreting fluvial networks and topographic metrics in slowly eroding landscapes. Plain Language Summary: The semi‐arid landscape of Santa Gracia, Chile is characterized by three different rock types: A monzogranite and two diorites. Initial field observations suggest a high stream density in areas underlain by monzogranite, whereas the diorites feature lower stream density, suggesting that rock type may exert a first‐order control over stream density. To test whether this is the case and if so why, we quantified stream density, hillslope curvature, and relief; the composition and properties of the rocks and soils; the vegetation density; the capacity of the soil to hold water; the sediment grain size; and the erosion rates, in areas underlain by each rock type. We found that the monzogranite has a higher stream density for two main reasons. First, because the chemical composition of the monzogranite is nutrient poor, its soils can grow less vegetation, reducing sub‐surface soil moisture and leaving more surface runoff available to carve stream channels. Additionally, the monzogranite bedrock underlaying the soil is more heavily weathered, and has a smaller grain size than the diorite, allowing for easier stream incision than the diorite. Because the rock type dictates the points of initial channel incision, we conclude that rock type can indeed control the spacing of stream channels. Key Points: Quantification of stream erosivity and soil diffusivity in neighboring plutons that vary in composition and grain sizeDrainage density varies by a factor of two due to differences in stream erosivity likely caused by contrasts in erodibility and runoffLithology affects erodibility through weathering intensity, grainsize, vegetation cover, and potentially infiltration [ABSTRACT FROM AUTHOR]

Different tillage methods can have varying effects on soil properties and crop quality. Therefore, field experiments were conducted at the Teaching and Research Farm of Landmark University, located in Omu‐Aran, Kwara State. The objectives were to investigate the impacts of various tillage methods on soil characteristics and the growth, yield, mineral and proximate content of soybean (Glycine max (L.) Merr.). Based on these objectives, it was hypothesized that soil properties, growth, yield, mineral and proximate contents of soybean would react differently to different tillage methods. Consequently, experiments were conducted to validate this hypothesis. The treatments were four tillage methods: manual clearing (MC), ploughing (P), ploughing plus harrowing (P + H) and manual ridging (MR), replicated three times in a randomized complete block design. Data on the initial soil properties (bulk density, particle size, pH, organic matter, N, P, K, Ca and Mg), along with the chemical properties of the soil on a per‐plot basis at the end of the experiment, were collected. Additionally, data on soil bulk density, porosity, moisture content and temperature were collected during the vegetative growth of the soybean. Soybean plant height and the number of branches were recorded at the midflowering stage, while grain yield and the number of pods were recorded at harvest. Soybean seeds were later analysed for their mineral and proximate contents using standard methods. P + H resulted in lower soil bulk density than other tillage methods and led to higher growth, yield, proximate and mineral contents of soybean. In MC, bulk density, soil moisture content, soil organic matter, N, P, K, Ca and Mg were significantly higher and temperature lower than in other tillage methods; yet, these advantages did not translate into increased yield and quality due to the higher bulk density. The growth, yield and quality of soybean were significantly influenced by soil bulk density rather than by soil chemical properties. Using the mean of the two sites, relative to MC, P and MR, P + H increased the grain yield of soybean by 41.3%, 24.4% and 13.7%, respectively. These findings underscore the importance of appropriate tillage practices for successful soybean cultivation in similar agroecological zones. For small‐scale operations, MR is suggested, while P + H is recommended for large‐scale soybean production in the studied area. Future studies could include additional variables, such as economic analysis, long‐term soil health impacts or the effects of tillage methods under varying climate conditions. [ABSTRACT FROM AUTHOR]

Sugar beet (Beta vulgaris L.) is a globally significant crop, valued for its economic importance in sugar production. Saline‐sodic soil environments negatively impact sugar beet productivity. This study investigates the effects of using compost, glauconite enriched‐K and their combinations in mitigating the saline‐sodic soil environment, sugar beet productivity and extracted sugar quality. A two‐season field experiment in split‐plot design with the main plots is three doses of compost: control (C0), recommended (100%) dose (C1) and 150% recommended dose (C2). Each group divided into four subplots of glauconite treatments arranged according to the recommended dose of potassium (K) as follows: G0 (no glauconite), G1 (50% K), G2 (100% K, 480 Kg glauconite Fed−1) and G3 (150% K). The results showed that compost and glauconite mitigated adverse soil effects caused by salinity and sodicity. The C2G3 treatment reduced electrical conductivity (EC) and exchangeable sodium percentage (ESP), improved organic matter and enhanced soil bulk density, porosity and penetration resistance. This combination also increased soil nutrients (N, K, Fe, Mn, Zn and Cu). Regarding the sugar beet yield, C2G3 improved root yield, top yield, sugar yield and extracted sugar. The application of glauconite increased root diameter by 20% and root length by 23%, enhanced sugar quality with minimal sugar losses to molasses (2.43%), and reduced impurities of K, α‐amino N and Na. Principal component analysis showed positive correlations between root yield and soil potassium, organic matter, cation exchange capacity and soil porosity, with negative correlations to bulk density, EC, pH and ESP. Two‐way analysis of main (ANOM) illustrated significant effects of compost and glauconite on soil–plant interactions. Multivariate analysis indicated that higher glauconite doses significantly enhanced root yield. The Gag run charts confirmed that compost (100%) and G3 levels explored more homogeneity reducing the ESP%, increasing sugar beet root yield, sugar yield and quality. [ABSTRACT FROM AUTHOR]

Microbial and microeukaryotic communities are extremely abundant and diverse in soil habitats where they play critical roles in ecosystem functioning and services that are essential to soil health. Soil biodiversity is influenced by above‐ground (vegetation) and below‐ground factors (soil properties), which together create habitat‐specific conditions. However, the compound effects of vegetation and soil properties on soil communities are less studied or often focused on one component of the soil biota. Here, we integrate metabarcoding (16S and 18S rRNA genes) and nematode morphology to assess the effects of habitat and soil properties shaping microbial and microeukaryotic communities as well as nematode‐associated microbiomes. We show that both vegetation and soil properties (soil bulk density) were major factors structuring microbial and microeukaryotic communities in semi‐arid soil habitats. Despite having lower nutrients and lower pH, denser soils displayed significantly higher alpha diversity than less dense soils across datasets. Nematode‐associated microbiomes have lower microbial diversity, strongly differ from soil microbes and are more likely to respond to microscale variations among samples than to vegetation or soil bulk density. Consequently, different nematode lineages and trophic groups are likely to display similar associated microbiomes when sharing the same microhabitat. Different microbiome taxa were enriched within specific nematode lineages (e.g. Mycobacterium, Candidatus Cardinium) highlighting potentially new species‐specific associations that may confer benefits to their soil nematode hosts. Our findings highlight the importance of exploring above‐ and below‐ground effects to assess community structure in terrestrial habitats, and how fine‐scale analyses are critical for understanding patterns of host‐associated microbiomes. [ABSTRACT FROM AUTHOR]

The interspecific trade‐off between growth versus mortality rates of tree species is thought to be driven by functional biology and to contribute to species ecological niche differentiation. Yet, functional trait variation is often not strongly correlated with growth and mortality, and few studies have investigated the relationships of both traits and niches, specifically encompassing above and belowground resources, to the trade‐off itself. These relationships are particularly relevant for seedlings, which must often survive resource limitation to reach larger size classes.We investigated the functional basis of the interspecific growth–mortality trade‐off and its relationship with ecological niches for seedlings of 14 tree species in a tropical forest in southwest China.We found evidence for an interspecific growth–mortality trade‐off at the seedling stage using 15 functional traits and 15 ecological niche variables. None of the organ‐level traits correlated with growth, mortality, nor the trade‐off, whereas specific stem length (SSL), a biomass allocation trait, was the only trait to have a significant correlation (positive). Moreover, light‐defined niches were not correlated with growth, mortality or the trade‐off, but soil‐defined niches did. Species at the faster growth/higher mortality end of the trade‐off were associated with higher fertility defined by lower soil bulk density and slope, and higher soil organic matter concentration and soil total nitrogen.Our findings indicate the importance of stem elongation and soil fertility for growth, mortality and their trade‐off at the seedling stage in this Asian tropical forest. Our findings contrast with analogous studies in neotropical forests showing the importance of photosynthesis‐related leaf traits related to insolation. Therefore, the functional drivers of demographic rates and trade‐offs, as well as their consequences for ecological niches, can vary among forests, likely owing to differences in biogeography, canopy disturbance rates, topography and soil properties. Moreover, the effects of functional trait variation on demographic rates and trade‐offs may be better revealed when biomass allocation is accounted for in a whole‐plant context. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) sequestration is increasingly emphasized as a climate mitigation solution, as scientists, policy makers, and land managers prioritize enhancing belowground C storage. To identify key underlying drivers of total SOC distributions, we compiled a global dataset of soil C stocks held in three chemical forms, reflecting different mechanisms of organic C protection: free particulate organic C (fPOC), physically protected particulate organic C (oPOC), and mineral‐protected soil organic C (mSOC). In our dataset, these three SOC pools were differentially sensitive to the effects of climate, soil mineralogy, and ecosystem type, emphasizing the importance of distinguishing between physical and chemical C protection mechanisms. C stocks in all three pools varied among ecosystems: cropland soils stored the least amount in each pool, with forest and grassland soils both containing significantly more fPOC (40%–60% greater in each ecosystem) than croplands. oPOC stocks did not significantly differ from zero in croplands but were substantial in forest and grassland soils. Meanwhile, mSOC stocks were the greatest in grasslands and shrublands (90%–100% greater than croplands). In cropland soils, there were no major effects of tillage on C storage in any of the three pools, while manure addition enhanced mSOC stocks, especially when added with inorganic N. Thus, the human land use intensity in croplands appears to reduce SOC storage in all major pools, depending upon management; retaining native vegetation should be emphasized to maintain current global SOC stocks. [ABSTRACT FROM AUTHOR]

Grazing annual forages in dryland cropping systems has been used to integrate crop and livestock systems, rejuvenate soils, enhance in-field nutrient cycling and soil organic carbon (SOC), and increase net returns by eliminating harvest expenses and feed delivery. However, cattle (Bos taurus) could potentially degrade soil physical properties by increasing compaction and reducing water infiltration in no-tillage (NT) systems. Minimum tillage (MT) may help correct some of these potential soil quality concerns. The objective of this study was to quantify MT effects on soil properties, forage mass, and weeds compared to NT in a grazed winter triticale [×Triticosecale Wittm. ex A. Camus (Secale × Triticum)] annual forage system from 2020 to 2022 near Jetmore, KS. The experiment had two tillage treatments, NT and MT (sweep plow to a depth of 5–13 cm twice during summer fallow), in a grazed continuous winter triticale cropping system. Bulk density was greater in June, pre-till (1.31 g cm−3), compared to August, post-till (1.23 g cm−3), across tillage treatments. The mean weight diameter of dry aggregates decreased, and wind-erodible fraction increased with MT. Across years, the mean weight diameter of water-stable aggregates was greater with NT compared to MT. The SOC stocks did not differ between tillage practices near the soil surface, but MT increased SOC at the 5- to 15-cm depth. Nitrate (NO3-N) concentration was 28% higher with MT compared to NT across depths at the August sampling time. Soil pH was slightly lower in NT (5.81) compared to MT (5.94). Penetration resistance was high due to frequently dry soil conditions, but there were no differences between tillage systems. Early-season forage biomass was greater in MT compared to NT in one out of two seasons. Our findings suggest that MT could be used to mitigate adverse effects of grazing on soil bulk density in NT systems but could cause short-term decreases in dry and wet aggregate stability and increased wind-erodible fraction. [ABSTRACT FROM AUTHOR]

Physicochemical characteristics of soil, especially organic matter and soil texture, affect the optimal plant density in rice (Oryza sativa L.). A split-plot field experiment was done based on a randomized complete block design (RCBD) in four replications in Amol (Northern Iran) on the coastal strip of the Caspian Sea. The experimental treatments, that is, soil fertility (infertile, semi-fertile, and fertile) as the whole-plot factor and plant density (low, medium, and high by 15.2, 19.6, and 27.8 plants m−2, respectively) as the split-plot factor, were studied over 2 years (2022 and 2023). The results indicated the greatest and smallest number of days from planting to tillering and from tillering to flowering for infertile soil, respectively. The maximum root fresh weight was measured during the tillering stage for infertile soil, whereas for fertile soil, the highest root fresh weight was recorded throughout the phases of panicle initiation and flowering. The greatest root length was measured at the tillering stage for 2022 in high-density infertile soil. The lowest number of panicles m−2 and the percentage of full spikelets were obtained from infertile soil. The highest grain yield was obtained from high-density fertile soil. In mechanized rice cultivation, high density is suggested for fertile and semi-fertile soils and low density for infertile soil. [ABSTRACT FROM AUTHOR]

Repetitive use of heavy farm machinery in cultivated agriculture may cause soil compaction that can adversely affect soil‐health‐related properties. Cover crops (CC) are well‐documented to alleviate problems associated with compaction and improve overall soil health in time. The objective of this field study was to evaluate the cumulative effects of CC treatment (i.e., with ≥ 6 years cereal rye [Secale cereale L.] CC and ≥ 4 years with no cover crop [NCC]) and sample/measurement placement (i.e., in the bed [B] and in the wheel‐track [WT] and no‐wheel‐track [NWT] furrow) on near‐surface soil physical‐, chemical‐, and infiltration‐related properties in an alluvial soil under cotton (Gossypium hirsutum L.) production in the Lower Mississippi River Valley. Samples were collected and in‐situ measurements were conducted in late May 2019 within a single field in eastern Arkansas. Overall‐infiltration rate was two times greater (p ≤ 0.01) in B compared to WT and NWT placement, which did not differ. Soil bulk density in WT was 1.1 times greater than the other two placements, while soil organic matter was greater in CC‐WT (30.7 Mg ha−1) than in all other treatment‐placement combinations, except for CC‐NWT, which did not differ. Similarly, water‐stable‐aggregate concentration was 2.3 and 1.6 times greater in the CC‐NWT and CC‐WT combinations, respectively, which did not differ, compared to under NCC. Results demonstrated that CC benefits extended beyond the bed to positively affect soil properties in adjacent WT and NWT furrows. Continued small‐scale, long‐term management studies using CC will extend insight into site‐specific, soil‐health improvements. Core Ideas: Cover crop use in cotton production reduced compaction and improved soil health in eastern Arkansas.Soil bulk density was greater in wheel‐track than in the bed and no‐wheel‐track placements.Soil organic matter was greatest in cover crop‐wheel and no‐wheel track treatment‐placement combinations.Wheel‐ and no‐wheel‐track water‐stable aggregation was greater in cover than no‐cover treatments. [ABSTRACT FROM AUTHOR]

Long‐term comparisons over several years between organic and synthetic management are lacking in sports turf research. Our objective was to investigate playing surface qualities and soil properties over an 8‐year period. For this trial, Kentucky bluegrass (KBG, Poa pratensis L.) sod was established and annually inter‐seeded with perennial ryegrass (Lolium perenne L.) and KBG. Factors included height of cut (3.2 and 6.4 cm) and management systems (MSs; synthetic and organic) with three replicates. Synthetic practices included chemical fertilizers and pesticides, while the organic system used hand‐weeding and biological fertilizers (leaf compost and naturally derived organics) with biological controls. In all years, wear was simulated in the fall using a slip‐wear machine and evaluated for playing qualities including visual wear tolerance, ball bounce (BB), surface hardness, and traction. Soil properties were evaluated in some years including pH, soil organic matter (SOM), soil bulk density, soil aggregate stability (SAG), and soil available P. Both MS received the same total N of 196 kg ha−1 year−1 but P applied varied with the MS (synthetic, 7.6 kg ha−1 year−1; organic, 23.2 kg ha−1 year−1). Synthetic practices provided acceptable visual wear tolerance (1–9, ≥6 acceptable) in 4 of 8 years compared to only 1 year for organic practices. Shorter cut grass (3.2 cm) consistently provided better visual wear tolerance (average = 5.6), harder surfaces (average = 51 g), and higher BB (average = 35.8%) consistent with accepted player standards. Synthetic practices afforded better tolerance to wear compared to organic practices in 5 of 8 years but little difference was observed in the other surface properties. Organic practices were consistently above 6.0 in soil pH (higher by 12%), 20% higher in soil available P, 25% higher in SOM, and with lower soil bulk density. SAG was higher following 8 years of simulated traffic by the last year of the test under organic practices. Results suggest competing benefits with synthetic practices affording better wear tolerance while organic practices promote better soil health. [ABSTRACT FROM AUTHOR]

The Eurasian woodcock prefers habitats where its main prey, earthworms, can be found in higher densities. Although they are forest‐dwelling birds, they regularly visit pastures and natural grasslands at night, where earthworm abundance is generally higher. However, there is little information on fine‐scale habitat use in relation to variation in habitat characteristics and prey availability, particularly beyond the breeding season. In our study, we investigated if the nocturnal occurrence of woodcocks during migratory stopover periods differed between two neighbouring fields, or management units, with similar vegetation structure, and if within‐field variation in the spatial patterns of woodcock sightings were associated with fine‐scale earthworm densities and soil parameters. Specifically, we used GPS tracking data of two tagged woodcocks and direct observation data to study patterns of occurrence of birds in a mixed forest‐pasture landscape in Hungary during pre‐ and post‐breeding periods. We compared these patterns with fine‐scale soil characteristics and earthworm abundance, acquired by field sampling. We found that the field with higher earthworm abundance was visited by woodcocks more frequently, and this correlation was similarly observed at the intra‐field level. Our results demonstrate that woodcocks select foraging sites with higher earthworm densities at multiple spatial scales, both between fields (coarse scale), and within fields (fine‐scale). Considering that woodcocks tended to return to the same field to forage at night, the strong associations between occupancy and resources provide a basis for developing habitat management strategies at the field level for conservation. As earthworm densities and soil parameters are good indicators of woodcock foraging habitat, measuring those variables, at least at a coarse scale, could aid in predicting important habitats for the species across the landscape. [ABSTRACT FROM AUTHOR]

Skid trails are a major management‐induced disturbance in temperate forest ecosystems with considerable impact on soil ecological processes that are so far poorly understood. In German forests, skid trails comprise 10%–20% of the forest area that is potentially affected by soil compaction through heavy machinery. We systematically investigated the influence of skid trails on physical, chemical and microbiological soil parameters at 84 paired plots across four Central European forest types.In low mountain forests with steeper topography, skid trails had more drastic effects than in lowland forests. Skid trails in low mountain areas showed a decrease in the C to N ratio of microbial biomass (MBC/MBN), as well as increased microbial (MBC/SOC) and enzyme activities leading to faster carbon turnover (lower C/N, EOC/EN) and increased CO2 losses (CO2/SOC) from the soil.The overall effects of the skid trails in lowland forests were small. On base‐poor soils, we found an increase in the MBC/MBN ratio, while skid trails in base‐rich lowland soils showed a reduction in CO2/SOC, suggesting a proportional increase in soil carbon storage.Regardless of region‐specific effects, the relative increase in the bulk density of the fine soil was identified as a 'golden trait' that determined the effects of skid trails on many soil parameters, as shown by negative correlations with SOC, N, MBC, MBN, MBP, MBC/SOC and CO2/SOC and positive ones with the activities of certain hydrolytic enzymes.Synthesis and applications: Our data clearly showed that carbon conversion processes and soil respiration leading to significant carbon and nutrient losses increased significantly on skid trails in low mountain regions with relatively steep slopes, which was in sharp contrast to lowland sites. The strong context dependence of our findings suggests that the mapping of soil conditions in terms of slope, substrate and moisture with high spatial resolution is mandatory to assess the vulnerability of sites to soil compaction by heavy machinery. Based on such vulnerability analysis, negative impacts can be minimised through the designation of permanently fixed skid trails, technical adaptation of vehicles (e.g. wide base tyres) as well as careful planning and timing of management operations that should be restricted to dry weather and soil moisture conditions or periods of frost. [ABSTRACT FROM AUTHOR]

The storage of organic carbon in the soils of salt marshes and other coastal blue carbon ecosystems has gained considerable attention by the scientific community for more than a decade now, while the relevance and mechanisms of soil inorganic carbon accumulation remain poorly understood. Using long‐term annual accretion monitoring over 17 years in N = 50 permanent plots distributed across a 1050‐ha salt‐marsh complex of the European Wadden Sea, we identified clear relationships between salt‐marsh vertical growth rates and the soil densities of inorganic and organic carbon. Specifically, we demonstrate a strong positive correlation between vertical accretion and inorganic carbon density while observing a strong negative correlation between vertical accretion and organic carbon density. This decoupling observed between inorganic and organic soil carbon stocks was governed by plant community composition and associated plant traits, which controlled sedimentation processes. [ABSTRACT FROM AUTHOR]

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

Soil compaction and soil bulk density are key soil properties affecting soil health and soil ecosystem services like crop production, water retention and purification and carbon sequestration. The standard method for soil bulk density measurements using Kopecky rings is very labour intensive, time consuming and leaves notable damage to the field. Accurate data on bulk density are therefore scarce. To enable large‐scale data collection, we tested a new portable gamma ray sensor (RhoC) for in situ field and dry bulk density measurements up to 1 m depth. In this first validation study, measurements with the RhoC‐sensor were compared with classic ring sampling. Measurements were made in two agricultural fields in the Netherlands (a sandy clay loam and a sandy soil), with large variation in subsoil compaction. At 10 locations within each field, three soil density profiles were made. Each profile comprised six depth measurements (every 10 cm from 10 to 60 cm depth) using the RhoC‐sensor and Kopecky rings, resulting in 30 pairwise profiles and 180 measurements in total per field. At an average soil density of 1.5 g/cm3, the relative uncertainty was 9% for the Kopecky rings and 15% for the RhoC‐sensor. Because the RhoC‐sensor is easy and quick to use, the higher relative uncertainty can easily be compensated for by making additional measurements per location. In conclusion, the RhoC‐sensor allows a reliable quantitative in situ assessment of both field and dry bulk density. This provides the much‐needed possibility for rapid and accurate assessment of soil compaction. The acquisition of this data supports the calculation of soil organic carbon stocks and is indispensable for (national) soil monitoring, to assess soil health and to inform sustainable land management practices for sustained or improved soil health and provision of soil ecosystem services, such as requested in the proposed EU Directive on Soil Monitoring and Resilience. [ABSTRACT FROM AUTHOR]

Revegetation is an effective measure to enhance soil organic carbon (OC) and nitrogen (N) storage in drylands, but the underlying processes remain poorly understood. Based on density fractionation, the free light fraction (fLF), the occluded light fraction (oLF), and a heavy fraction (HF) were extracted from a chronosequence of revegetated sites aged 10, 22, 34, 48, and 65 years. A mobile sand dune (MSD) was used as the reference site (aged 0 years). The OC and N contents of different fractions and the bulk soils were determined to evaluate the impacts of revegetation and clarify post-revegetation stabilization mechanisms for the OC and N. The results showed that the dry mass of fLF and oLF in established shrublands were 17.16-31.30 and 17.68-44.87 times greater than those in the MSD, respectively, while the amount of HF decreased by 1.09%-2.51% in 65 years. The contents and stocks of OC and N and C:N ratio in each fraction significantly increased over time but decreased with soil depth, and these three variables decreased sequentially from fLF to oLF to HF. The OC and N contents and their ratios in each fraction were positively and linearly correlated with their corresponding values in the bulk soil. The OC and N percentages contained in the fLF and oLF increased significantly, but those in the HF decreased with increasing site age. Despite this, more than 55.08% of OC and 80.59% of N were remained in the HF across all the sites, indicating that the enhancement of OC and N stocks in SOM following revegetation were mainly derived from an increase in OC and N in protected fractions. Biological and physicochemical factors including microbial biomass C and N, the availability of N, P, and K, bulk density, and clay and silt contents, were the key factors regulating the OC and N dynamics in the density fractions. The initial OC and N accumulation after revegetation occurs mainly in the HF, while vegetation development shifts the OC and N from stable to labile pools. The OC and N accumulation in revegetated soils is attributed to the changes in both the LF and HF whereas OC and N in the light fraction become increasingly important over time. Stabilization by forming aggregates and mineral associations may dominate the long-term OC and N sequestration in restored ecosystems. [ABSTRACT FROM AUTHOR]

Understanding historical changes in root depth attributes is needed for crop productivity and sustainability assessments, but such information is rare. We explored whether newer maize (Zea mays L.) hybrids grow roots faster and deeper than older hybrids and quantified the role of management and environment on root trait expression. We measured root front velocity (RFV) and maximum root depth in 11 Bayer Crop Science legacy hybrids released from 1983 to 2017 across five environments in the US Corn Belt during 2021 and 2022. Root depth was measured weekly during vegetative stages with manual probes and the maximum root depth at crop harvest with a Giddings probe. Results indicated that the RFV and maximum root depth slightly increased with the year of hybrid release (0.13% per year, p = 0.1) at 8.7 plants m−2. Historical increases in plant density from 4.7 to 8.7 plants m−2 lowered RFV and maximum root depth, but the new hybrids compensated for this loss, resulting in 4% higher RFV and 3% higher maximum depth when comparing systems from 1983 to 2017. The environment strongly influenced root trait expression (>41%). Rain anomaly and soil bulk density explained a portion of this variation. We found a linear relationship between root depth and leaf number (R2 = 0.95) and a nonlinear relationship between RFV and maximum root depth (R2 = 0.77), which can stimulate crop model improvements. Faster and deeper roots were not correlated with maize yields in our environments. This study enhances our understanding of maize breeding impacts on root traits. Core Ideas: We studied root front velocity (RFV) and maximum root depth in maize hybrids released from 1983 to 2017.RFV and maximum root depth increased by 0.13% per year, a 10‐fold lower increase than grain yield genetic gain.Root depth and collared leaf number were strongly correlated (R2 = 0.95).The environment had the strongest influence on the root depth traits.Faster and deeper roots did not necessarily translate into higher yields. [ABSTRACT FROM AUTHOR]

Soil bulk density (BD) is important for measuring changes in soil chemical, physical, and biological properties; however, the measurement is tedious to collect and requires specialized equipment. Database measurements for soil surface BD do not always correspond to present field conditions as field management can alter BD in time. Saturation percentage (SP) is a routine lab measurement. The objectives of this study are to (1) understand if a relationship between BD and SP can be developed and (2) build a model that predicts BD based on a routine low‐cost lab analysis. We collected 83 soil samples from different experimental sites around California's Central Valley. At each site, BD, SP, soil organic matter (OM), and soil total organic carbon were measured. A set of models were generated and compared based on their Akaike information criterion (AIC) and adjusted R2. The best two models are presented in this paper, and their accuracy and precision in estimating BD were further compared by calculating the root mean square error (RMSE) and the R2 of the predicted versus values measured in the field. We determined that a strong relationship between BD and SP exists (R2 = 0.70) and that a cubic model that includes SP and OM resulted in the best model to predict BD in California soils. Inclusion of additional data may further strengthen this model or make it applicable for other grower regions. Core Ideas: Database bulk density values may not correspond to field conditions as management can alter bulk density.Bulk density is hard to measure and requires specialized equipment, but is needed to quantify soil carbon changes.There is a significant correlation between soil bulk density, soil saturation paste, and soil organic matter.Three models to predict bulk density based on saturation paste and organic matter were developed and evaluated. [ABSTRACT FROM AUTHOR]

In recent years, there has been a substantial conversion of croplands and grasslands to short rotation Eucalyptus globulus plantations in the northern highlands of Ethiopia. This has raised concerns among researchers, policymakers, and environmentalists regarding potential adverse effects on soil fertility. To address these concerns, a study was conducted to evaluate the impact of Eucalyptus globulus plantations on selected soil physicochemical properties in the region. The study involved four land-use types, comprising two age groups of Eucalyptus globulus plantations (4-year-old and 9-year-old), as well as areas designated for grasslands and croplands. Soil sampling was carried out in 10 m × 10 m subplots within each experimental plot, and standard methods were employed for soil analysis. The soil laboratory results were statistically analyzed using Two-way ANOVA and Pearson's correlation coefficients in R software version 4.1.0. The findings revealed significant variations (p < 0.05) in soil bulk density, soil organic carbon, and soil pH between the 4 -year-old and 9-year-old Eucalyptus globulus plantations and the grasslands. A notable difference (p < 0.05) in exchangeable acidity was observed between the 4-year-old and 9-year-old E. globulus plantations, with the latter exhibiting the highest mean exchangeable acidity (6.20 ± 0.76). However, no significant differences (p < 0.05) were observed between the Eucalyptus plantations and the grasslands in available phosphorus (Av.P), exchangeable calcium (Ca2+), sodium (Na+), and magnesium (Mg2+) concentrations, as well as cation exchange capacity (CEC). The study results has, therefore, implied that Eucalyptus globulus plantations induced changes in specific soil properties with varying stand ages in the study area. Nonetheless, it was emphasized that further long-term research is necessary to comprehend the effects of these plantations on soil properties. [ABSTRACT FROM AUTHOR]

To compare the disparities between free water evaporation and soil water evaporation, and unveil the temporal impact of soil water evaporation in diverse environments, a series of experiments were conducted to observe the soil water content in different temperature and humidity environments. Meanwhile, the soil water characteristic curve (SWCC) and the evaporation process of free water in air were determined, and the sensitivities of temperature, humidity and density on the soil water evaporation process were analysed. The results demonstrated that both external temperature and humidity can serve as variables for controlling the evaporation rate of soil water. These factors exerted a dynamic influence on the evaporation process, with the impact of each factor tending to stabilize as soil water content decreased. The evaporation rate of soil water was higher than that of free water at the initial stage and was lower than that of free water after the soil reached the residual water content; soil water tended to exist in a state with higher entropy than that of free water. This study provides valuable insights for the establishment of a soil water evaporation model. [ABSTRACT FROM AUTHOR]

Agricultural practices that lead to soil carbon sequestration may be a win–win strategy for mitigating global warming and improving soil fertility and resource use efficiency. The mechanisms through which soil organic carbon (SOC) concentration affects crop yields are numerous but difficult to separate. The objective of this study was to disentangle these processes and estimate to what extent the yield response to SOC is mainly driven by changes in physical or biochemical properties and processes. This was achieved by analysing the response of yields in continuous maize to SOC concentrations during 20 years (2000–2019), which had evolved in 14 experimental treatments in a Swedish long‐term field experiment at Ultuna since 1956, ranging from 0.94% to 3.65% in the topsoil (0–20 cm). Average maize yields during this period varied between 1.9 and 8.4 Mg dry mass per hectare in the different treatments. The treatments comprise applications of different mineral nitrogen (N) fertilizers and organic amendments and combinations thereof. Our analysis showed that maize yield in the treatments that were not severely limited by nitrogen supply or soil acidity increased by 16% for each percentage unit increase in SOC. We applied the widely used concept of critical N concentration in plant biomass to diagnose the N status in maize in the different treatments (N nutrition index [NNI]) and parameterized a response function between yield and pH (RpH). Dry soil bulk density (BD) was used as a proxy for soil physical properties. These three variables NNI, RpH and BD explained 95% of the variation in maize yields among treatments. Further analysis of the relationship between BD, SOC and plant available water capacity revealed that about two thirds of the yield increases in response to SOC change could be ascribed to associated changes in soil physical properties. Our analysis suggests that the extra storage capacity of water, which increased by up to 15 mm in the topsoil for each unit percentage increase in SOC, was the main driver for the observed yield responses. We conclude that measures for increasing SOC in soils most likely are an effective adaptation strategy for reducing the risk of crop damage during dry spells, which probably are becoming more frequent in the future due to climate change, even in relatively humid climates as in Sweden. [ABSTRACT FROM AUTHOR]

We examined whether and how woody debris removal for domestic fuel affects carbon storage and soil properties in an Indian rainforest. Fuelwood removal reduced aboveground carbon stocks, increased soil bulk density, and possibly reduced soil phosphorus stocks. Equitably balancing this subtle trade‐off between climate‐regulating and vital, widely utilized provisioning functions, is a challenge for tropical forest research and management. [ABSTRACT FROM AUTHOR]

The tree crown is a useful measure of tree vigour and is highly relevant to a tree's environmental adaptability. Crown allometry depends on environmental and stand conditions. Several studies have focussed on the effects of climate change and competitive intensity on the crown, but the regulatory role of soil resources and diversity on crown allometry and carbon allocation has been neglected.Data from 20,994 trees in 232 mixed forests collected between 2011 and 2019 were located near four major mountain ranges in northeast China. The proposed crown width model includes the stand developmental stage, soil, climate, competition intensity, species mixture, species diversity, structural diversity and their interactions.We observed that the cross‐species allometric scaling exponent does not conform to the universal scaling law. Our results showed that crown width increased with increasing soil bulk density, quadratic mean diameter and coefficient of diameter variation but decreased with increasing de Martonne aridity index, basal area, Simpson index and species mixture. The interaction between quadratic mean diameter and soil bulk density had a significant negative effect on crown width. The influence of a particular factor within the interaction term on crown width was modulated by the gradients of other factors. Furthermore, soil bulk density contributed more to crown width modelling than the aridity index, and structural diversity had a greater effect on crown width than species diversity.Synthesis. Our results provide new insights into the environmental variability of crown allometry in mixed forests under global change, which is critical for improving regional and global estimates of forest biomass and carbon stocks. [ABSTRACT FROM AUTHOR]

Premise: Plants grown at high densities show increased tolerance to heavy metals for reasons that are not clear. A potential explanation is the release of citrate by plant roots, which binds metals and prevents uptake. Thus, pooled exudates at high plant densities might increase tolerance. We tested this exclusion facilitation hypothesis using mutants of Arabidopsis thaliana defective in citrate exudation. Methods: Wild type Arabidopsis and two allelic mutants for the Ferric Reductase Defective 3 (FRD3) gene were grown at four densities and watered with copper sulfate at four concentrations. Plants were harvested before bolting and dried. Shoot biomass was measured, and shoot material and soil were digested in nitric acid. Copper contents were determined by atomic absorption. Results: In the highest‐copper treatment, density‐dependent reduction in toxicity was observed in the wild type but not in FRD3 mutants. For both mutants, copper concentrations per gram biomass were up to seven times higher than for wild type plants, depending on density and copper treatment. In all genotypes, total copper accumulation was greater at higher plant densities. Plant size variation increased with density and copper treatment because of heterogeneous distribution of copper throughout the soil. Conclusions: These results support the hypothesis that citrate exudation is responsible for density‐dependent reductions in toxicity of metals. Density‐dependent copper uptake and growth in contaminated soils underscores the importance of density in ecotoxicological testing. In soils with a heterogeneous distribution of contaminants, competition for nontoxic soil regions may drive size hierarchies and determine competitive outcomes. [ABSTRACT FROM AUTHOR]

The growing needs for agricultural production require maintaining and improving soil fertility through fertilization. However, most research to date in Ethiopia particularly in the Tigray regional state has focused on the effects of soil chemical properties and relatively little work has been done on soil physical properties. The objective of this study was to assess the effects of compost, blended (NPSZn), and potassium chloride (KCl) fertilizers on soil bulk density (BD) and moisture content (SMC). Therefore, a field experiment was carried out for 2018-2019 years to study the influence of sole and combined application of compost, NPSZn, and KCl fertilizers on BD and SMC in clay loam and loamy sand soil textures in Tigray. Two compost (0 and 20 t·ha−1), three NPSZn (0, 60, and 120 kg·ha−1), and four KCl (0, 120, 210, and 300 kg·ha−1) rates replicated three times were arranged in split-split plot design and allocated to main, sub, and sub-subplots, respectively. BD (g·cm−3) and SMC (%) data were collected from 0 to 10 and 0 to 30 cm soil depths before and after harvesting in 2018 and 2019, respectively. Sole and combined application of the fertilizers considerably influenced BD and SMC in both soil textural groups and years. Compost applied in combination with NPSZn at 120 kg·ha−1 and KCl at 300 kg·ha−1 significantly reduced BD (1.24 g·cm−3 in 2018 and 1.22 g·cm−3 in 2019) in clay loam soils as compared to all treatments. Similarly, the lowest BD (1.5 g·cm−3 in 2018 and 1.47 g·cm−3 in 2019) was observed in loamy sand soils. The highest volumetric SMC (21% in both years) was observed in clay loam soil in plots treated with compost. Likewise, the highest SMC (12% in 2018 and 11% in 2019) was found in loamy sand soils in compost-treated plots. This study demonstrated that SMC and BD can be improved through compost and compost combined with NPSZn and KCl application, respectively, in the drylands of Northern Ethiopia. [ABSTRACT FROM AUTHOR]

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Citrus plants are host to several plant parasitic nematodes (PPNs), which are microscopic organisms. Among PPNs, the citrus root nematode, T. semipenetrans (Cobb 1913) (Tylenchida: Tylenchulidae), causes significant damage to citrus plantations worldwide. Understanding citrus nematode populations, precise identification, host preference among citrus species, and damage threshold are crucial to control T. semipenetrans. The minutiae of citrus plant–nematode interactions, nematode density and molecular nematode identification are not well understood. In this study, nematode species and density in citrus orchards, host specialization, molecular and morphological characteristics of nematodes were assessed.Molecular and morphological methods, host–nematode interactions, host (citrus species) preference, damage economic threshold (ET), and economic injury level (EIL) were determined using laboratory methods and field sampling. Citrus plantations in different provinces in the Mediterranean region of Turkey were investigated.Nematode species were identified molecularly and morphologically. ITS sequences revealed that samples were infected by citrus root nematode T. semipenetrans. The lowest nematode density was in C. reticulata in Mersin (53 2nd stage juveniles (J2s) 100 g−1 soil), while the highest density was from Hatay in C. sinensis (12173 J2s 100 g−1 soil). Highest citrus nematode population density was on roots of C. reticulata, followed by C. sinensis, C. limon, and C. paradisi.The citrus nematode is more common than was thought and population fluctuations change according to specific citrus species. Environmental conditions, host and ecological factors, such as temperature, soil pH, and soil nutrients, might influence nematode populations in citrus orchards. Investigating nematode density in diverse soil ecologies and the responses of different resistant/tolerant citrus species and cultivars to nematode populations is essential in future studies. [ABSTRACT FROM AUTHOR]

Soil water content (SWC) and soil temperature (ST) are important indicators of environmental change in permafrost regions. In this study, we conducted soil sampling at 89 locations in the Three Rivers Headwaters Region (TRHR) to investigate the individual and synergistic effects of environmental factors on SWC and ST. We used multivariable regression and random forest modelling to analyse the data. The results show that SWC and ST were higher in the southeast TRHR than in the northwest and higher in surface layers than deeper soil layers. The most important factors affecting SWC in the 0–20 cm and 20–40 cm soil layers were soil bulk density and precipitation, while bulk density was the most important factor in the 40–60 cm layer, and soil bulk density and steppe vegetation were the most important factors in the 60–80 cm layer. For ST, altitude, temperature and slope gradient were the drivers in the 0–20 cm surface layer, while altitude and temperature were the most critical drivers in the 20–40 cm, 40–60 cm and 60–80 cm layers. Overall, bulk density and altitude were the key environmental factors influencing SWC and ST values, respectively. The outcomes of this study provide valuable insights into the environmental factors that impact the SWC and ST in permafrost regions, which can guide decision‐making processes for sustainable soil management in the context of climate change. [ABSTRACT FROM AUTHOR]

Soil bulk density (BD) is a principal component in estimating the density of soil nutrients and elements including carbon (C). Current literature states that in soils with rock fragment (RF) content ≥3% of the total sample volume, substantial differences in estimated soil organic carbon density (SOCD) are found, depending on the soil BD calculation method chosen, potentially affecting the accuracy of soil nutrient and C inventories. In many soil surveys, soil BD is not measured directly, or the core method is used as the sole determinant of soil BD, potentially neglecting the soil volume dilution effect of RFs larger than the diameter of the cores used. This study uses the core and quantitative pit methods at 10 forest sites in Ireland to determine the BD and RF mass and volume to a depth of 40 cm. The authors examine how large RFs impact BD and subsequently affect the estimated SOCD values by comparing against reference values from established soil sampling and BD calculation methods. The analysis reveals significant variations in the estimated SOCD values when the RF volume in the soil sample exceeds 8% of the total sample volume. A novel method, hereafter named "core‐scaling," combines core and pit sampling methods to account for large RF mass and volume in BD calculations. This study suggests that using the core‐scaling method provides results that are strongly correlated with the pit method, thus offering an alternative that can also provide accurate SOCD estimates in soils with a high RF content. Core Ideas: Soil carbon inventories in stony soils need to account for rock fragments larger than commonly used core diameters.Depending on the BD sampling‐calculation method used, significant disparities in SOCD results were observed.Combining elements of core and pit sampling enables the dilution effect of large RF to be more efficiently estimated.The novel "core‐scaling" method increases sampling efficiency and the accuracy of SOCD estimates.Pit and core‐scaling method SOCD results are more comparable than pit and core method SOCD results. [ABSTRACT FROM AUTHOR]

Peat and other organic soils (e.g., organo‐mineral soils) show distinctive volume changes through desiccation and wetting. Important processes behind volume changes are shrinkage and swelling. There is a long history of studies on shrinkage which were conducted under different schemes for soil descriptions, nomenclatures and parameters, measurement approaches, and terminologies. To date, these studies have not been harmonized in order to compare or predict shrinkage from different soil properties, for example, bulk density or substrate composition. This, however, is necessary to prevent biases in the determination of volume‐based soil properties or for the interpretation of elevation measurements in peatlands, in order to predict carbon dioxide emissions or uptake caused by microbial decomposition or peat formation. This study gives a comprehensive overview of shrinkage studies carried out in the last 100 years. Terminology and approaches are systematically classified. In part I, the concepts for shrinkage characteristics, measurement methods, and model approaches are summarized. Part II is a meta‐analysis of shrinkage studies on peat and other organic soils amended by own measurement data obtained by a three‐dimensional structured light scanner. The results show that maximum shrinkage has a wide range from 11% to 93% and is strongly affected by common soil properties (botanical composition, degree of decomposition, soil organic carbon, and bulk density). Showing a stronger correlation, bulk density was a better predictor than soil organic carbon, but maximum shrinkage showed a large spread over all types of peat and other organic soils and ranges of bulk density and soil organic carbon. Core Ideas: Shrinkage characteristics of organic and mineral soils differ strongly.Shrinkage of organic soils depends on botanical composition, degree of decomposition, and pedogenetic modification.Maximum shrinkage of organic soil varied between 11% and 93%.For all types of organic soil, bulk density was more suitable to explain maximum shrinkage than SOC.Neglecting shrinkage biases the determination of volume‐based soil properties (e.g., bulk density and porosity). [ABSTRACT FROM AUTHOR]

Microplastics have been found in large quantities in agricultural soil and now become a major global issue. Different types of microplastic have adverse effects on agricultural soil. The most widely used method for the extraction of microplastics in agricultural soil is the density floatation method by using saturated NaCl solution. This method includes the pre‐digestion of soil samples with H2O2 to remove all the organic matter present in the soil. Different types of microplastic particles were extracted and identified by using ATR‐FTIR viz polypropylene, polybutylene tetrapthalate, polyethylene, polystyrene, and polyethylene tetrapthalate. The crystalline nature of extracted microplastic was checked by employing XRD analytical technique. Floatation with higher density saturated sodium chloride (NaCl) solution recovered approximately 80% MPs from soil. Floatation methods were found to be effective for extracting microplastics from soils. [ABSTRACT FROM AUTHOR]

Climate warming leads to widespread permafrost thaw with a fraction of the thawed permafrost carbon (C) being released as carbon dioxide (CO2), thus triggering a positive permafrost C-climate feedback. However, large uncertainty exists in the size of this model-projected feedback, partly owing to the limited understanding of permafrost CO2 release through the priming effect (i.e., the stimulation of soil organic matter decomposition by external C inputs) upon thaw. By combining permafrost sampling from 24 sites on the Tibetan Plateau and laboratory incubation, we detected an overall positive priming effect (an increase in soil C decomposition by up to 31%) upon permafrost thaw, which increased with permafrost C density (C storage per area). We then assessed the magnitude of thawed permafrost C under future climate scenarios by coupling increases in active layer thickness over half a century with spatial and vertical distributions of soil C density. The thawed C stocks in the top 3 m of soils from the present (2000-2015) to the future period (2061-2080) were estimated at 1.0 (95% confidence interval (CI): 0.8-1.2) and 1.3 (95% CI: 1.0-1.7) Pg (1 Pg = 1015 g) C under moderate and high Representative Concentration Pathway (RCP) scenarios 4.5 and 8.5, respectively. We further predicted permafrost priming effect potential (priming intensity under optimal conditions) based on the thawed C and the empirical relationship between the priming effect and permafrost C density. By the period 2061-2080, the regional priming potentials could be 8.8 (95% CI: 7.4-10.2) and 10.0 (95% CI: 8.3-11.6) Tg (1 Tg = 1012 g) C year-1 under the RCP 4.5 and RCP 8.5 scenarios, respectively. This large CO2 emission potential induced by the priming effect highlights the complex permafrost C dynamics upon thaw, potentially reinforcing permafrost C-climate feedback. [ABSTRACT FROM AUTHOR]

Soil compaction has caused negative impacts on soybean productivity due to the excessive use of machinery and heavy agricultural implements in the cultivation areas. Effects of two levels of soil compaction were investigated on 60 soybean genotypes in a field experiment. Soil properties, weather conditions in the region and changes in agronomic characteristics of the crop were evaluated. The genotypes were divided into three groups according to the relative maturity group (RMG) and classified according to stress susceptibility. Compaction increased soil density and soil mechanical resistance to penetration, varying according to the registered rainfall regime. The genotype responses to compaction in the three groups, in general, were increased seedling emergence (EME), initial height (IH), number of nodes (NN), shoot dry matter (SDM), and final height (FH) of the plants. However, there was a reduction in the relative growth rate (RCR), in the number of pods (NP), and in grain yield (PROD). From the calculation of the stress susceptibility index (SSI) it was possible to identify tolerant and sensitive soybean genotypes to soil compaction stress. SSI and the relative trait change index (RTC) indicated the responses that the tolerant genotypes present under conditions of high mechanical impedance. Therefore, soil compaction provides greater seedling emergence and vegetative growth, but significant losses in soybean yield. Soil compaction‐tolerant genotypes show smaller reductions in relative growth rate, absolute growth rate, final height, number of pods, and grain yield. [ABSTRACT FROM AUTHOR]

Soil density fractionation is a common tool to separate organic matter of different function and turnover. But it has not been tested so far how much soil material is necessary to obtain reproducible results. A reduction of chemicals like polytungstate would further save valuable resources. Here, we show that soil weight reduction from 25 to 5 g was not significantly affecting fractionation results. Compared to the commonly used 10–25 g, this corresponds to a saving of resources of up to 80%. [ABSTRACT FROM AUTHOR]

Retrogressive thaw slumps (RTSs) have become a dominant geomorphic event in permafrost regions due to the modern climate change. However, the roles of topographic, vegetation, and soil factors in influencing the spatial distribution and recurrence of RTSs remain not fully understood. Here, we identified the formation and recurrence of 459 RTSs during 2008–2021 using satellite images of the central Qinghai‐Tibet Plateau (Northwest of the Beiluhe Basin, 239 km2). We found that the topographic and environmental attributes of the RTSs exhibited strong correlations with the variation in the RTS density. The RTS‐affected areas had a higher slope, elevation, relative slope position, normalized difference vegetation index, soil water content, and lower soil bulk density than other landscapes. Regarding the influence of topographic and environmental attributes on the activity status of RTSs during 2018–2020, we found that the higher slope, elevation, and soil water content were advantageous for the activity of the RTSs. The RTSs with larger sizes and presenting an elongated shape were more likely to be active. Additionally, we examined the variation of the headwall shape of RTSs based on the fractal dimension and UAV‐based orthophoto. We found that the headwall shape of RTSs becomes more complicated due to the small‐scale thawing of ice‐rich permafrost, which may further induce subsequent thaw slumping. Higher air temperature triggers new RTSs, and increased precipitation may be responsible for the further activity of RTSs. Our findings can enhance our understanding of the development pattern and mechanism of RTSs in permafrost regions. Plain Language Summary: Retrogressive thaw slumps (RTSs) have become more common on the Qinghai‐Tibet Plateau (QTP). They are treated as a key sign of permafrost degradation, as an RTS may continue to grow for decades until the ground ice supply is exhausted. A total of 459 warming‐induced RTSs were concentrated in the central of QTP during 2008–2021. We found that the RTSs were concentrated in regions with specific topographic and environmental attributes. RTSs with a larger scale and elongated shape were more likely to continuously expand. In the long term, higher air temperature may be the main reason for the formation of new RTSs, and increased precipitation may be responsible for the expansion of RTSs. Key Points: Retrogressive thaw slump (RTS) area had a higher slope, elevation, relative slope position, normalized difference vegetation index, and soil water content than landscapeRTSs with larger sizes and elongated shapes during 2018–2020 were more likely to be activeHigher air temperature triggers new RTSs, while increased precipitation may be responsible for their further activity [ABSTRACT FROM AUTHOR]

Soil Bulk Density (BD) is an extremely important variable because it is an important site characterization parameter, and it is highly relevant for policy development because it is mandatory for calculating soil nutrient stocks. BD can influence soil chemical properties, land‐use planning and agronomic management. The 2018 Land Use and Coverage Area Frame Survey (LUCAS) saw the unprecedented collection of BD core analysis in a subset of the locations in Europe and the United Kingdom where soil physical and chemical properties were analysed in the 2009 and the 2015 sampling campaigns. Here, we integrated the LUCAS 2018 BD sampling campaign with the mass fraction of coarse fragments previously determined in LUCAS 2009–2015 in order to provide a dataset of the volume fraction of coarse fragments and the BD of the fine earth and improve soil organic carbon (SOC) stock estimation accuracy for topsoil. BD data sampled at 0–10 and 10–20 cm were averaged to harmonize the BD with the mass fraction of coarse fragments measured in 2009, 2012 and 2015. Samples were from cropland, grassland and woodland soils, which accounted for 41%, 21% and 30%, respectively, of the total number of selected sites (n = 6059); 'bareland', and 'shrubland' accounted for 3% of the sites each, whereas 'artificial land' accounted for <1%. Only six samples were classified as 'wetland'. The dataset was produced assuming the mass density of the coarse fraction to be constant across all LUCAS soil samples. We also estimated the SOC stocks associated with LUCAS 2018 BD and SOC content measurements and showed that correcting the BD by the coarse mass fraction instead of the coarse volume fraction generates SOC stock underestimation. We found the highest deviations in woodlands and shrublands. We showed that, when SOC stock is computed with coarse mass fraction, the error compared with the computation by volume may vary depending on the SOC and coarse mass fraction. This may imply a SOC stock underestimation for European soils. This dataset fits into the big framework of LUCAS soil properties monitoring and contributes both to soil awareness and soil research and assessments, which are two important objectives of the Soil Strategy and the European Soil Observatory (EUSO). [ABSTRACT FROM AUTHOR]

The development of horizontal drilling and hydraulic fracking has led to an increase in oil and natural gas extraction. Development of infrastructure to extract and transport these resources is expected to increase over the next few decades, resulting in extensive land disturbance. Although reclamation aims to sufficiently return disturbed lands to their pre‐disturbance use in an ecological sense, reclaimed rights‐of‐ways (ROW) commonly produce reduced crop yields. The objective of this study was to use meta‐analysis to determine soil disturbance trends across studies found in the peer‐reviewed literature. Papers that reported soil property data on disturbed ROWs and adjacent undisturbed sites were retrieved by searching the Web of Science database. Papers were separated by climate regions, resulting in analyses being conducted for studies in semiarid and humid climate regions. Results indicate that soil bulk density, soil organic matter, and pH are significantly increased on reclaimed ROWs. Soil metrics not incorporated in meta‐analysis due to insufficient observations or the possible presence of publication biases like a desire to publish significant results and poor study design (cation exchange capacity, calcium, phosphorus, magnesium, total nitrogen, electrical conductivity, sodium, sodium adsorption ratio, and texture) are assessed and discussed. Best management practices gleaned from studies incorporated into meta‐analysis are discussed to provide strategies to limit soil property disturbances. Core Ideas: Soil bulk density, soil organic matter, and pH changed most post‐disturbances.Climate will influence long‐term impacts of disturbances due to parent materials and leaching water.Limiting the size of disturbance is best for long‐term recovery. [ABSTRACT FROM AUTHOR]

The article discusses concerns about the method used to calculate carbon dioxide removal (CDR) rates through enhanced rock weathering. The authors highlight flaws in the method developed by the research team of the for-profit supplier Eion Carbon, which render it unusable without modifications. They point out issues with the model for rare earth element (REE) concentration changes due to basalt addition to soils, lack of consideration of control data variability, and arbitrary selection of REEs and soil depth. Despite these concerns, the authors acknowledge that the overall carbon budget presented in the study may still be valid. They emphasize the importance of robustly addressing these issues before using the method in other studies or as part of monitoring, reporting, and verification (MRV) toolsets. The authors commend the data sharing practices of the study and encourage further development of robust monitoring tools for enhanced weathering. [Extracted from the article]

The rainfall intensity, slope, and underground pore density are major factors affecting the soil erosion of maize‐covered karst slopes. We studied the erosion process of maize‐covered karst slopes and the influencing mechanism of soil erosion on these slopes under different rainfall intensities, slopes, and underground pore density via simulated rainfall tests. The results are as follows: (1) No runoff was observed on the slope surface under light rainfall (30 mm hr−1); instead, subsurface flow was predominant. However, runoff from the surface and subsurface flows under moderate rainfall (60 mm hr−1) increased with the rainfall intensity. The average surface runoff under extreme rainfall (90 mm hr−1) was 2.3‐times that under moderate rainfall. In addition, the average subsurface runoff under extreme rainfall was 1.6‐ and 3.5‐times that under moderate rainfall and light rainfall, respectively. The total amounts of surface and subsurface soil losses increased as the rainfall intensity increased. The surface and subsurface soil losses from light to moderate and extreme rainfall events increased by 258% and 151%, respectively. The soil loss from the surface was 5.3‐times greater than that from the subsurface, indicating that the erosion of maize‐covered karst slopes mainly occurs on the surface and that the subsurface loss is relatively small. (2) As the slope angle increased, the runoff, sediment yield, and proportion of erosion on the surface increased, and vice versa. (3) The subsurface runoff and sediment yield increased as the underground pore density increased, while the opposite occurred on the surface. Multiple regression analysis showed that the rainfall intensity is the most critical factor affecting the soil erosion of maize ‐covered slopes in karst areas, followed by the slope, while the influence of the underground pore density is small. [ABSTRACT FROM AUTHOR]