European Journal of Soil Science最新文献

Mechanical soil disturbance is one among the key factors influencing soil biodiversity in agriculture. Although many soil organisms are sensitive to soil disturbance, fungi could be highly impacted due to their sessile lifestyle, relatively slow growth and filamentous body structure. Arbuscular mycorrhizal (AM) fungi are of particular interest in arable lands, providing crop plants with numerous vital services such as nutrient acquisition and protection against abiotic and biotic stressors. Considering this, tillage practices that aim to reduce soil disturbance are often seen as a fungal-friendly alternative to conventional inversion tillage. Although local studies exist on the impacts of minimal tillage practices on AM fungi, the universality of this approach has been debated. Our objective was to assess the effects of reduced tillage intensity on AM fungi in comparison with conventional tillage. Using high-throughput sequencing techniques in long-term field experiments in five European countries, we show that the effects of reduced tillage intensity may not necessarily be positive on soil AM fungal diversity. Plots which were tilled using reduced tillage techniques had lower AM fungal richness in three countries, whereas in one of them, no significant differences were found. We also observed a shift in AM fungal communities where prevalence of taxa preferring root colonisation rather than soil exploration increased under reduced tillage regimes. Here, we argue that more detailed and long-term studies are needed to understand the factors that could make the reduction of soil disturbance more beneficial to AM fungi if agricultural sustainability goals are to be met.

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.

Arbuscular mycorrhizal (AM) fungi form mutualistic relationships with the majority of land plants and are an important part of the soil microbial community in natural and agricultural ecosystems. These fungi promote water and nutrient acquisition by their host plant and regulate the allocation of photosynthetic carbon to soil. Both crop variety and environment affect naturally occurring mycorrhizal abundance in roots, but the relative importance of those factors for mycorrhization is largely unknown. In a field study covering a large pedoclimatic gradient across four European sites, we (i) compared the abundance of AM fungi in the roots of 10 modern winter wheat (Triticum aestivum L.) varieties, (ii) evaluated the relative importance of variety and site for the variability in root colonization by AM fungi and (iii) tested the relationship between mycorrhizal abundance and grain yield. Root colonization by arbuscules and hyphae ranged from 10% to 59% and 20% to 91%, respectively, across all samples and varied by 8% and 18%, respectively, among varieties when averaged across sites. Variance decomposition analysis revealed a 10 times higher importance of site than variety for AM fungal root colonization. Specifically, we found the highest mycorrhizal abundance on the site with the most arid conditions and the lowest on the sites with low soil pH and high nutrient availability. Despite the low variability in mycorrhizal abundance among varieties, there were significant differences in both arbuscular and hyphal root colonization. However, this did not translate into an increase in yield as no significant relationships between mycorrhizal abundance at flowering and grain yield were detected. The consistent differences between wheat varieties in root colonization by AM fungi across European field sites underline that genetic drivers of mycorrhization are to some extent independent of the site. This highlights the relevance of breeding practices to shape a wheat variety's capacity for mycorrhizal symbiosis across a range of environmental conditions.

The paradigm of modernity is associated with human detachment from soil as the agricultural and affective foundation of modern societies. The focus on soil as a resource has created increasingly exhausted landscapes. Soil science is well placed to (re)build the urgently needed connection between humans and nature by generating evidence for soil functioning and, perhaps most importantly, by establishing linkages with diverse types of soil knowledge and integrating them in collaborative solutions. Such transdisciplinary solutions can be achieved by transforming current ways of doing soil science, which begin with soil scientists. Anchored in feminist and critical thinking, we used the ‘reflecting and doing’ framework (Lopez et al., 2023) to demonstrate how reflexivity can help soil science to become a transformative space. By partially dissolving the mind–heart and human–soil dualisms, we can foster a way of generating soil knowledge that emerges from the relations within and beyond the human Self. Such an approach is relatively new in academic soil science, which relies heavily on the scientific method as a detached form of knowing that privileges mind over body, reason over emotion, culture over nature and production over reproduction. We argue that this journey starts with (re)positioning ourselves as soil scientists in relation to our research and advance a Transformative Soil Science that recognizes soil knowledge as situated and embodied and that identifies soil as the main ally for a sustainable world.

Adsorption kinetics of three organic phosphate compounds (OPs) with varying molecular sizes and structures and inorganic phosphate (Pi) were investigated on α-Al₂O₃ and poorly crystalline goethite. The organic phosphates were inositol hexaphosphate (IHP), glycerol phosphate (GlyP) and glucose-6-phosphate (G6P), and the inorganic phosphate was KH₂PO₄. Batch adsorption experiments were performed at 25°C. We tested the sorption kinetic data using various non-linear models/equations and on their transformed linear forms by applying appropriate statistics. Besides, we also used a modified non-linear equation having four parameters to this effect. Data were found to fit best with the modified equation and described the whole sorption process satisfactorily. For sorption of compounds on to the surface of these minerals, the equation with four parameters may be used in contrast with many standard equations applied for kinetic studies in soils. Sorption was described to take place in two processes: a fast one that takes place in less than 45 min and a slow one that takes place in several hours or more. The rate of the slow process did not depend directly on the concentration of phosphate compounds in solution, but depended linearly on the amount of phosphate that was adsorbed during the fast process. These initially adsorbed ions carrying some amount of negative charge likely hindered the movement of subsequent adsorbate ions to the solid surface due to decreased surface potential. This caused the variation in fast and slow sorption rate constants. Sorption densities increased in the order, Pi >Gly P >G6P >IHP, which revealed that the sorption density and initial sorption rate of OPs decreased with increasing molecular weights of OPs.

Modifying root systems by crop breeding has been attracting increasing attention as a potentially effective strategy to enhance the sustainability of agriculture by increasing soil organic matter (SOM) stocks and soil quality, whilst maintaining or even improving yields. We used the new soil-crop model USSF (Uppsala model of Soil Structure and Function) to investigate the potential of this management strategy using winter wheat as a model crop. USSF combines a simple (generic) crop growth model with physics-based descriptions of soil water flow, water uptake and transpiration by plants. It also includes a model of the interactions between soil structure dynamics and organic matter turnover that considers the effects of physical protection and microbial priming on the decomposition of SOM. The model was first calibrated against field data on soil water contents and both above-ground and root biomass of winter wheat measured during one growing season in a clay soil in Uppsala, Sweden using the GLUE method to identify five ‘acceptable’ parameter sets. We created four model crops (ideotypes) by modifying root-related parameters to mimic winter wheat phenotypes with improved root traits. Long-term (30-year) simulations of a conventionally tilled monoculture of winter wheat were then performed to evaluate the potential effects of cultivating these ideotypes on the soil water balance, soil organic matter stocks and grain yields. Our results showed that ideotypes with deeper root systems or root systems that are more effective for water uptake increased grain yields by 3% and SOM stocks in the soil profile by ca. 0.4%–0.5% in a 30-year perspective (as an average of the five parameter sets). An ideotype in which below-ground allocation of dry matter was increased at the expense of stem growth gave even larger increases in SOM stocks (ca. 1.4%). An ideotype combining all three modifications (deeper and more effective root systems and greater root production) showed even more promising results: compared with the baseline scenario, surface runoff decreased while yields were predicted to increase by ca. 7% and SOM stocks in the soil profile by ca. 2%, which is roughly equivalent to ca. 20% of the 4-per-mille target (https://4p1000.org/).

This study describes iron (Fe) pipestems formed around and within root channels during the development of a homogeneous unripe sulfidic sediment into a ripe soil where redox- or pH-active elements segregate. Pipestems and adjacent soil material samples were characterised by chemical and mineralogical analyses and scanning electron microscopy (SEM) associated with energy dispersive spectroscopy (EDS). Pipestems occurred at 60–190 cm and at 30–130 cm in a young Finnish soil and a more mature Australian soil, respectively, while sulfidic materials were found below 170–180 cm. The pipestems consisted of mineral grains cemented together by Fe precipitate. There was an up to 24-fold enrichment of Fe and an up to 13-fold enrichment of sulfur (S) in the Finnish pipestems compared to the adjacent soil material, whereas the corresponding enrichment in the Australian soil was up to 27-fold for Fe and up to 8-fold for S. In the Australian pipestem matrices, the Fe concentration was as high as 40% compared to 14% in the Finnish ones. It was estimated that about 70 ton ha⁻¹ S had been mobilised from the sulfidic material in the Finnish soil at the depth of 50–150 cm. Part of S has leached out but a substantial amount remained in the soil constituting the stock of retained acidity. Almost all pipestems contained a new solid phase precipitated within the former cortex cells of the plant roots. In the Finnish samples, this precipitate consisted of jarosite and schwertmannite. After oxidative exhaustion of sulfidic material in the surrounding soil, these metastable minerals are gradually hydrolysed, associated with leaching of S. In the mature Australian soil, most of these minerals had already been transformed to goethite. Pipestems formed after roots in unripe soil are sites for synthesis and hydrolysis of minerals and serve as routes for atmospheric oxygen into the reduced subsoil and for soluble reaction products to exit the soil. Pipestems have an important role in the ripening of the soil profile.

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.

Peat makes up approximately a quarter of Scotland's soil by area. Healthy, undisturbed, peatland habitats are critical to providing resilient biodiversity and habitat support, water management, and carbon sequestration. A high and stable water table is a prerequisite to maintain carbon sink function; any drainage turns this major terrestrial carbon store into a source that feeds back further to global climate change. Drainage and erosion features are crucial indicators of peatland condition and are key for estimating national greenhouse gas emissions. Previous work on mapping peat depth and condition in Scotland has provided maps with reasonable accuracy at 100-m resolution, allowing land managers and policymakers to both plan and manage these soils and to work towards identifying priority peat sites for restoration. However, the spatial variability of the surface condition is much finer than this scale, limiting the ability to inventory greenhouse gas emissions or develop site-specific restoration and management plans. This work involves an updated set of mapping using high-resolution (25 cm) aerial imagery, which provides the ability to identify and segment individual drainage channels and erosion features. Combining this imagery with a classical deep learning-based segmentation model enables high spatial resolution, national scale mapping to be carried out allowing for a deeper understanding of Scotland's peatland resource and which will enable various future analyses using these data.

Genomic evidence suggests that lysogenic viruses significantly influence the evolution of their host communities and soil microbial ecology and functionality. However, the response of soil viral reproductive strategies (VRS) to environmental factors, in particular soil water stress, remains poorly understood. We investigated this by employing a laboratory microcosm incubation system with different soil moisture levels (30%, 60% and 90% field capacity). Our study focused on soil biochemical properties, bacterial and viral populations, lysogenic fractions and virus/bacteria ratio (VBR). The results showed that soil moisture significantly affected bacterial and viral counts, lysogenic fractions and VBR (p < 0.01), with bacterial counts increasing and viral counts decreasing with increasing soil moisture. The lysogenic fraction peaked at low moisture, suggesting a shift in viral strategy under hydration stress, which may affect virus-bacteria interactions and nutrient dynamics, enhancing host adaptability. Analyses using correlation, random forest and structural equation modelling identified soil moisture as the dominant factor shaping VRS by altering nutrient availability and host population. These findings provide a new insight into microbial regulation of feedback to environmental change from the life history strategies of soil viruses.