Changes In Soil Conditions Research Articles

Model‐based assessment of the impact of agri‐environment scheme options and short‐term climate change on plant biodiversity in temperate grasslands

Abstract Agri‐environment schemes (AES) incentivise land‐management practices aimed at mitigating environmental impacts. However, their effectiveness depends on the duration and type of management. We modelled the potential for grassland AES options in Wales (UK) to achieve positive changes in plant diversity via change in soil conditions. We modelled the response of plants and soils to the predicted effects of AES options over a 13‐year time interval. We applied scenarios of change in soil conditions in three managed grassland types, using high‐resolution baseline soil and vegetation data collected in grasslands across Wales, UK. We also applied scenarios of climate change to determine the extent to which this might modify the impact of AES intervention on plant species compositional turnover. Empirical models of soil response to extensification were constructed from published experimental data and used to drive change in soil inputs to a small ensemble of ecological niche models for British plants. These models were applied to the local pool of species in each baseline (2 × 2 m) quadrat plus a wider 10 × 10 km pool from which we draw species absent at baseline but predicted to find conditions suitable as a result of AES intervention and climate change, thus estimating dark diversity at each location. Outputs were summarised by grouping species by the ecosystem functions and services they support and by matching projected species composition to the UK National Vegetation Classification. Scenario modelling indicated that at least 10 years of management under grassland AES options were needed to achieve conditions suitable for desirable plant assemblages more typical of lower fertility habitats. Synthesis and applications: We predict that management effects will have a more marked effect on vegetation and soil than predicted climate variation up to 2029. Realising modelled changes in habitat suitability as species compositional turnover and community assembly is likely to require additional measures to assist plant dispersal and establishment.

Strong Dispersal Limitation of Microbial Communities at Shackleton Glacier, Antarctica.

Microbial communities can be structured by both deterministic and stochastic processes, but the relative importance of these processes remains unknown. The ambiguity partly arises from an inability to disentangle soil microbial processes from confounding factors, such as aboveground plant communities or anthropogenic disturbance. In this study, we characterized the relative contributions of determinism and stochasticity to assembly processes of soil bacterial communities across a large environmental gradient of undisturbed Antarctic soils. We hypothesized that harsh soils would impose a strong environmental selection on microbial communities, whereas communities in benign soils would be structured largely by dispersal. Contrary to our expectations, dispersal was the dominant assembly mechanism across the entire soil environmental gradient, including benign environments. The microbial community composition reflects slowly changing soil conditions and dispersal limitation of isolated sites. Thus, stochastic processes, as opposed to deterministic, are primary drivers of soil ecosystem assembly across space at our study site. This is especially surprising given the strong environmental constraints on soil microorganisms in one of the harshest environments on the planet, suggesting that dispersal could be a driving force in microbial community assembly in soils worldwide. IMPORTANCE Because of their diversity and ubiquity, microbes provide an excellent means to tease apart how natural communities are structured. In general, ecologists believe that stochastic assembly processes, like random drift and dispersal, should dominate in benign environments while deterministic processes, like environmental filtering, should be prevalent in harsh environments. To help resolve this debate, we analyzed microbial community composition in pristine Antarctic soils devoid of human influence or plant communities for eons. Our results demonstrate that dispersal limitation is a surprisingly potent force of community limitation throughout all soil conditions. Thus, dispersal appears to be a driving force of microbial community assembly, even in the harshest of conditions.

Soil biodiversity supports the delivery of multiple ecosystem functions in urban greenspaces.

While the contribution of biodiversity to supporting multiple ecosystem functions is well established in natural ecosystems, the relationship of the above- and below-ground diversity with ecosystem multifunctionality remains virtually unknown in urban greenspaces. Here we conducted a standardized survey of urban greenspaces from 56 municipalities across six continents, aiming to investigate the relationships of plant and soil biodiversity (diversity of bacteria, fungi, protists and invertebrates, and metagenomics-based functional diversity) with 18 surrogates of ecosystem functions from nine ecosystem services. We found that soil biodiversity across biomes was significantly and positively correlated with multiple dimensions of ecosystem functions, and contributed to key ecosystem services such as microbially driven carbon pools, organic matter decomposition, plant productivity, nutrient cycling, water regulation, plant-soil mutualism, plant pathogen control and antibiotic resistance regulation. Plant diversity only indirectly influenced multifunctionality in urban greenspaces via changes in soil conditions that were associated with soil biodiversity. These findings were maintained after controlling for climate, spatial context, soil properties, vegetation and management practices. This study provides solid evidence that conserving soil biodiversity in urban greenspaces is key to supporting multiple dimensions of ecosystem functioning, which is critical for the sustainability of urban ecosystems and human wellbeing.

Assessment of land reclamation status using remote sensing and GIS in territory of Pakhtakor district of Uzbekistan

The importance of land distribution across all sectors of the national economy cannot be overstated, particularly in agriculture. Agricultural land plays a critical role in meeting the population's food needs and satisfying the demand for raw materials in the industry. The fertility of the land is the main productive property in agriculture. Continuous improvements in land productivity, combined with the adoption of innovative technologies, are key factors in modern agriculture development. However, natural and anthropogenic factors are negatively impacting agricultural land productivity, leading to a decrease in productivity. To prevent this, urgent measures must be taken to improve the reclamation conditions of agricultural lands, develop regions following climate change, and effectively organize cadastral reclamation activities. Additionally, monitoring the reclamation condition of agricultural lands is crucial in times of scarcity. This research focuses on the assessment of the melioration condition of agricultural land in the Pakhtakor district of the Republic of Uzbekistan, using geoinformation technologies and remote sensing data. These technologies enable the low-cost, timely, and high-accuracy measurement of changes in soil conditions over large land areas. By continuously monitoring the earth's surface, we can identify existing problems and develop timely solutions to address them. In research, enhancing agricultural land productivity is a critical task for modern agriculture development. Innovative technologies and effective monitoring strategies, such as geoinformation and remote sensing techniques, are essential to achieving this goal. Through this research, we hope to contribute to the continued improvement of land management practices and sustainable agriculture in Uzbekistan.

Leaf phenology rather than mycorrhizal type regulates soil nematode abundance, but collectively affects nematode diversity in seven common subtropical tree species

The underlying mechanisms of the relationships between tree species and the soil micro-food web in forest ecosystems remain uncertain, primarily ascribed to an insufficient understanding on how tree functional traits drive soil nematode communities, including in subtropical forests. We investigated the impacts of seven subtropical tree species (evergreen: Pinus massoniana, Mytilaria laosensis, Ilex chinensis, Michelia macclurei; and deciduous: Liquidambar formosana, Quercus acutissima, and Betula luminifera) on the soil nematode communities. We found that the abundance of soil nematodes was not affected by mycorrhizal types, but it was around 83% higher under the deciduous trees than the evergreen trees, indicating the importance of leaf phenology to the abundance of soil nematodes. Nonetheless, both the evergreen and the arbuscular mycorrhizal trees increased soil nematode diversity, resulting from changes in root traits and soil properties. Furthermore, root traits (root C, root N, and root C:N ratio), and soil properties (total C, total N, moisture content, and bulk density) were the best predictors of the community composition of soil nematodes, indicating a key role of resource quality and soil microhabitat in regulating soil nematodes. In contrast, the ectomycorrhizal trees had lower plant parasite and Wasilewska indices, and evenness, whereas the evergreen trees slightly improved the evenness of soil nematodes. This study suggests that tree species affect the soil food web through changes in soil conditions and plant functional traits in subtropical forests.

Satellite observed delaying effects of increased winds on spring green-up dates

Wind speeds have substantially changed over the Northern Hemisphere during the past a few decades, and such changes have been shown to have important implications for the growth, chemical composition, structure, and morphology of terrestrial ecosystems. However, the effects of wind change on the spring leaf green-up date (GUD) remain largely unknown. Using both 89 sites of flux measurements (972 site-year in total) and satellite observations over 1982–2015, here we show that higher winds in the spring preseason contributed to the delayed GUD for 29.8% of northern ecosystems, and various factors controlled the strength of the delaying effects. We further show that the earlier GUD with climate change was offset roughly by 24.4 ± 3.7% due to the increase of wind. Higher winds potentially caused delayed GUD by changes in soil conditions and differences between daytime and night-time temperatures. A higher precipitation could likely compensate the drying effects of winds on GUD. Among different vegetation types, soil water and water use efficiency were the most important regulators of the sensitivity of GUD to wind for all plant functional types, while evapotranspiration regulated grasslands and shrubs. Our results identified the new role of wind change on the spring phenology in respective of satellite observations, and future ecosystem models might consider these effects for a better representation of the responses of vegetation phenology to climate change.

Quantitative and qualitative assessment of pine seedlings under controlled undergrowth disturbance: Fire and soil scarification

Scots pine (Pinus sylvestris L.) is the most widespread forest tree species in Central Europe. The range of Scots pine depends on the influence of forest management on stand species composition, as the potential for the natural regeneration of Scots pine monocultures is smaller than the current range of the species. To achieve regeneration, pine requires specific ecological conditions, including adequate soil preparation. The literature notes that the effective natural regeneration of pine requires fire or mixing the organic soil layer with the mineral layer. This hypothesis was critically evaluated carrying out work with the main objective of comparing the germination and growth dynamic of pine seedlings in two variants, simulating fire or soil scarification against natural conditions. The research focused on analyzing the growth of pine seedlings from germination to the final number of seedlings, which remained unchanged until the end of the experiment. The evaluation was carried out in soil monoliths from Kampinos National Park (KNP), in which seeds from a homogeneous mother stand were planted. The quantitative and qualitative characteristics of the seedlings were statistically evaluated, including analyses of their root system characteristics. The results confirmed the positive effect of mixing an organic and mineral layer at the germination stage and during the subsequent growth of the pine. The seedlings had a high survival rate (65.3%). However, the positive effect of fire on the regenerative capacity of pine could not be confirmed; the number of obtained seedlings (29.5%) was significantly lower than in the control variant. In addition, the “fire variant” was characterized by high seedling mortality immediately after germination. Root systems were important for the survival of the seedlings, the development of which was affected by the tested variant. The analyses performed may have implications for the development of research on the possible natural regeneration of Pines after natural disturbances. Additional topic that needs further research is the response of seedling root systems to changes in soil conditions.

Effects of the changes in soil conditions due to land rolling on the growth of barley (Hordeum vulgare L.)

Abstract This study aimed to determine the changes in soil properties due to land rolling after sowing and analysis the effects of these changes in soil properties on the plant growth in barley (Hordeum vulgare L.) production. For this purpose, a field experiment was conducted by using three weights of the land roller (196.37, 337.67, 478.97 kg/m) and untreated control treatment after sowing barley. The results showed that land rolling significantly changed the soil properties such as bulk density, moisture content, and penetration resistance. These changes in soil conditions significantly affected the plant growth parameters in barley production. The increased bulk density at the 0 ‒ 100 mm depth of the soil due to land rolling increased the seed emergence, the plant growth parameters and the yield of barley. However, it was observed that the grain yield per ear started decreasing at the higher penetration resistance than 345, 486, and 630 kPa for 50 mm, 75 mm and 100 mm, respectively. Consequently, it can be said that the use of a land roller after sowing in barley production can increase the yield by improving the plant growth parameters and soil physical properties under the soil and climate conditions like the experimental field.

Geotechnical Measurements for the Investigation and Assessment of Arctic Coastal Erosion—A Review and Outlook

Geotechnical data are increasingly utilized to aid investigations of coastal erosion and the development of coastal morphological models; however, measurement techniques are still challenged by environmental conditions and accessibility in coastal areas, and particularly, by nearshore conditions. These challenges are exacerbated for Arctic coastal environments. This article reviews existing and emerging data collection methods in the context of geotechnical investigations of Arctic coastal erosion and nearshore change. Specifically, the use of cone penetration testing (CPT), which can provide key data for the mapping of soil and ice layers as well as for the assessment of slope and block failures, and the use of free-fall penetrometers (FFPs) for rapid mapping of seabed surface conditions, are discussed. Because of limitations in the spatial coverage and number of available in situ point measurements by penetrometers, data fusion with geophysical and remotely sensed data is considered. Offshore and nearshore, the combination of acoustic surveying with geotechnical testing can optimize large-scale seabed characterization, while onshore most recent developments in satellite-based and unmanned-aerial-vehicle-based data collection offer new opportunities to enhance spatial coverage and collect information on bathymetry and topography, amongst others. Emphasis is given to easily deployable and rugged techniques and strategies that can offer near-term opportunities to fill current gaps in data availability. This review suggests that data fusion of geotechnical in situ testing, using CPT to provide soil information at deeper depths and even in the presence of ice and using FFPs to offer rapid and large-coverage geotechnical testing of surface sediments (i.e., in the upper tens of centimeters to meters of sediment depth), combined with acoustic seabed surveying and emerging remote sensing tools, has the potential to provide essential data to improve the prediction of Arctic coastal erosion, particularly where climate-driven changes in soil conditions may bias the use of historic observations of erosion for future prediction.

INFLUENCE OF AGRICULTURAL TRACTORS ON SOIL COMPACTION

Agriculture needs both wheeled and tracked tractors, as not all operations are rational to perform only wheeled machines. Before carrying out agricultural operations, it is necessary to comprehensively assess the consequences of changes in soil condition after tillage, choosing in advance a rational type of tractor and implements. When performing energy-intensive operations, it is necessary to try to use a tractor with a caterpillar engine. Agricultural enterprises need to recommend the optimal composition of the fleet depending on the type of soil, area of cultivated fields, the range of crops and solve the problem of long and efficient use of fertile land, taking into account not only costs and yields, but also negative impact on soil. As a result, productivity will increase, soil fertility will be preserved, operating costs will be reduced, and AIT productivity will increase. These considerations should be taken into account when determining the niche of tracked vehicles in the production and formation of the tractor fleet

Detection of rice plant disease using AdaBoostSVM classifier

AbstractThe research in the detection of plant diseases using plant images based on machine learning is widely increased in the field of agriculture. This could be done with the images of infected rice (Oryza sativa L.) plants. The changes in atmospheric condition cause changes in soil condition and in temperature. Both air temperature and soil temperature have distinct roles in crops, which can also lead to diseases in rice plants. In this paper, a prototype is developed for the detection of rice plant diseases like bacterial leaf blight, brown spot, and leaf smut. The proposed prototype is developed by undergoing experiments on image processing using machine learning algorithms. Several images of rice leaf which are infected by diseases had been captured and preprocessed using a median filtering technique. The important features are extracted by using Discrete Wavelet Transform (DWT) for the diseased part of the leaf images. Then the green parts of the leaf have been removed, so as to extract the diseased part. The features are extracted based on the attributes like color, shape, and texture. For multiclass classification process, Adaptive Boosting support vector machine (AdaBoostSVM) Classifier is used. The proposed prototype results in the accuracy of about 98.8% in detecting and classifying the rice leaf disease.

Improving Nitrogen Use Efficiency in Aerobic Rice Based on Insights Into the Ecophysiology of Archaeal and Bacterial Ammonia Oxidizers.

The abundance and structural composition of nitrogen (N) transformation-related microbial communities under certain environmental conditions provide sufficient information about N cycle under different soil conditions. This study aims to explore the major challenge of low N use efficiency (NUE) and N dynamics in aerobic rice systems and reveal the agronomic-adjustive measures to increase NUE through insights into the ecophysiology of ammonia oxidizers. Water-saving practices, like alternate wetting and drying (AWD), dry direct seeded rice (DDSR), wet direct seeding, and saturated soil culture (SSC), have been evaluated in lowland rice; however, only few studies have been conducted on N dynamics in aerobic rice systems. Biological ammonia oxidation is majorly conducted by two types of microorganisms, ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). This review focuses on how diversified are ammonia oxidizers (AOA and AOB), whose factors affect their activities and abundance under different soil conditions. It summarizes findings on pathways of N cycle, rationalize recent research on ammonia oxidizers in N-cycle, and thereby suggests adjustive agronomic measures to reduce N losses. This review also suggests that variations in soil properties significantly impact the structural composition and abundance of ammonia oxidizers. Nitrification inhibitors (NIs) especially nitrapyrin, reduce the nitrification rate and inhibit the abundance of bacterial amoA without impacting archaeal amoA. In contrast, some NIs confine the hydrolysis of synthetic N and, therefore, keep low NH4+-N concentrations that exhibit no or very slight impact on ammonia oxidizers. Variations in soil properties are more influential in the community structure and abundance of ammonia oxidizers than application of synthetic N fertilizers and NIs. Biological nitrification inhibitors (BNIs) are natural bioactive compounds released from roots of certain plant species, such as sorghum, and could be commercialized to suppress the capacity of nitrifying soil microbes. Mixed application of synthetic and organic N fertilizers enhances NUE and plant N-uptake by reducing ammonia N losses. High salt concentration promotes community abundance while limiting the diversity of AOB and vice versa for AOA, whereas AOA have lower rate for potential nitrification than AOB, and denitrification accounts for higher N2 production. Archaeal abundance, diversity, and structural composition change along an elevation gradient and mainly depend on various soil factors, such as soil saturation, availability of NH4+, and organic matter contents. Microbial abundance and structural analyses revealed that the structural composition of AOA was not highly responsive to changes in soil conditions or N amendment. Further studies are suggested to cultivate AOA and AOB in controlled-environment experiments to understand the mechanisms of AOA and AOB under different conditions. Together, this evaluation will better facilitate the projections and interpretations of ammonia oxidizer community structural composition with provision of a strong basis to establish robust testable hypotheses on the competitiveness between AOB and AOA. Moreover, after this evaluation, managing soils agronomically for potential utilization of metabolic functions of ammonia oxidizers would be easier.

Soil properties of North Iberian wet heathlands in relation to climate, management and plant community

Background and aimsHeathlands are a broad vegetation type characterized by the dominance of evergreen shrub species that thrive on nutrient-poor soils, thus sensitive to small changes in soil conditions. Here we aimed to identify soil gradients related to climate, management and main species in wet heathlands.MethodsSoil nutrient levels, organic matter and acidity were studied at two soil depths on ninety plots from 18 sites in Erica mackayana wet heaths of NW Iberian Peninsula, in relation to presence and cover of structural plant species (shrubs and graminoids) at two scales: plot and site (landscape) scale.ResultsWe identified one main soil gradient explained by soil organic matter (SOM), the effective cation exchange complex (eCEC), available phosphorus (P), and Aluminium-Calcium ratio (Al:Ca). Cattle density had a positive correlation with the main gradient in the surface layer, all other climate and management factors were unrelated to soil conditions. Molinia caerulea had a positive relation with SOM, eCEC, basic cations and low Al:Ca ratio. Erica cinerea showed the opposite reaction at both scales. Ulex gallii showed a negative correlation with C:N ratio at the plot scale and deeper layer.ConclusionSOM accumulation, low nutrient levels and Al toxicity explain the uniqueness of E. mackayana heathland vegetation and soils. Main indicator species react to soil conditions at plot and landscape scales. Cattle density correlated positively with soil nutrient levels, but density of wild ponies is unrelated to soil conditions. Large herbivores, especially ponies, are needed for conservation management of these heathlands.

Diverse responses of pqqC- and phoD-harbouring bacterial communities to variation in soil properties of Moso bamboo forests.

SummaryPhosphate‐mobilizing bacteria (PMB) play a critical role in the regulation of phosphorus availability in the soil. The microbial genes pqqC and phoD encode pyrroloquinoline quinone synthase and bacterial alkaline phosphatase, respectively, which regulate inorganic and organic phosphorus mobilization, and are therefore used as PMB markers. We examined the effects of soil properties in three Moso bamboo forest sites on the PMB communities that were profiled using high‐throughput sequencing. We observed differentiated responses of pqqC‐ and phoD‐harbouring PMB communities to various soil conditions. There was significant variation among the sites in the diversity and structure of the phoD‐harbouring community, which correlated with variation in phosphorus levels and non‐capillary porosity; soil organic carbon and soil water content also affected the structure of the phoD‐harbouring community. However, no significant difference in the diversity of pqqC‐harbouring community was observed among different sites, while the structure of the pqqC‐harbouring bacteria community was affected by soil organic carbon and soil total nitrogen, but not soil phosphorus levels. Overall, changes in soil conditions affected the phoD‐harbouring community more than the pqqC‐harbouring community. These findings provide a new insight to explore the effects of soil conditions on microbial communities that solubilize inorganic phosphate and mineralize organic phosphate.

Shrub encroachment enhances the infiltration capacity of alpine meadows by changing the community composition and soil conditions

Due to global changes and anthropogenic disturbances shrubs are widely encroaching into alpine meadows, which may have profound impacts on the ecohydrological functioning of these key ecosystems. This phenomenon is particularly alarming in the alpine meadows of the Qinghai-Tibetan Plateau, the headwaters for many of Asia’s largest rivers. However, little is known about the extant in which shrub encroachment alters the infiltration capacity of those soils. Here we examined the effects of shrub encroachment on the plant community and soil infiltration processes by contrasting vegetation and infiltration variables between three areas: a reference alpine meadow, an alpine meadow lightly encroached by smaller shrubs, and an alpine meadow heavily encroached by larger shrubs. We found that shrub encroachment reduced herbaceous plants aboveground biomass by 10–24 g m−2 and root biomass by 1346–2239 g m−2. The sedge functional group was gradually replaced by forbs. Initial infiltration rates gradually increased with shrub encroachment, and were approximately doubled and tripled at the earlier and later stages of encroachment, respectively. Overall, shrub encroachment improved the soil infiltrability by changing soil conditions and inhibiting herbaceous species due to the reduction of surface mattic epipedon and the formation of dead root channels. These findings suggest that the rapid transformation of alpine meadows into shrublands could have drastic effects on the surface runoff and streamflow dynamics of the Qinghai-Tibetan Plateau.

Changes in soil conditions before and after earthquakes at a repetitive soil liquefaction site in Taiwan

Beishih Village of Hsinhua Township in southern Taiwan is a unique location for studying soil liquefaction. Soil liquefaction has been observed at the same site after earthquakes in 1946, 2010, and 2016, each of which had a Richter magnitude greater than six. This recurrence provides an opportunity for analyzing soil condition variations resulting from soil liquefaction. Seismic data sets have been collected in 2011, 2014, 2016, and 2017. We have used seismic refraction tomography and the multichannel analysis of surface waves to estimate P- and S-wave velocities. In S-wave velocity profiles, low shear velocity zones have been located beneath sand volcanoes shortly after two earthquakes and have disappeared four years after a 2010 earthquake. However, the P-wave velocity has been less sensitive to soil condition changes, possibly because groundwater obscures the effect of soil liquefaction on velocity profiles. In addition, we use seismic wave velocities to determine the importance of soil properties such as Poisson’s ratio, shear modulus, and porosity to identify the cause of the low shear velocity zone. Notably, although porosity decreases after soil grain rearrangement, sand and clay mixing increases the Poisson’s ratio, reducing the shear modulus of the soil. In addition, a soil layer between 2 and 7 m and a deeper layer below 10 m that resulted in sand volcanoes have been liquefied. We also consider how the evaluation of soil liquefaction potential can be affected by long-term variations in soil conditions and changes resulting from liquefaction. The factor of safety is used to evaluate the liquefaction potential of the site. The results reveal that the assessment conducted long after the earthquake underestimated risk because the soil developed shear strength after the earthquake.

Mobilization and methylation of mercury with sulfur addition in paddy soil: Implications for integrated water-sulfur management in controlling Hg accumulation in rice

Sulfur-fertilizer is commonly applied in croplands and in immobilizing Hg in contaminated soil. However, there is still great uncertainty and controversy concerning Hg transportability and transformation when supplying sulfur in paddies with complex conditions. Herein, we explored the effect of adding sulfate in paddy soil at different rice growth stages on soil Hg release and MeHg accumulation in rice and uncovered the correlation between sulfur induced MeHg production and the dynamically changed soil Eh, dissolved Fe, and dissolved organic carbon (DOC). In specific, sulfate addition at early stages (flooding period) triggered the decrease of Eh and increase of DOC and dissolved Fe, which in turn promoted Hg release and favored MeHg generation (increased by 235.19–555.07% vs control). Interestingly, adding sulfate at late stages (drainage condition), as compared with that at early stages, alleviated Hg release and MeHg production accompanied by the increase of Eh and decrease of dissolved Fe and DOC. The microcosmic experiment further confirmed the reduction of sulfate to sulfide promoted the change of Eh, thereby stimulating HgS dissolution in soil extract. The results give clues on the rational application of sulfur-fertilizer and through the water-sulfur fertilizer management considering the correspondingly changed soil conditions to diminish Hg bioavailability and MeHg production in paddies and paddy-like environments.

Trophic niche but not abundance of Collembola and Oribatida changes with drought and farming system.

Higher frequencies of summer droughts are predicted to change soil conditions in the future affecting soil fauna communities and their biotic interactions. In agroecosystems drought effects on soil biota may be modulated by different management practices that alter the availability of different food resources. Recent studies on the effect of drought on soil microarthropods focused on measures of abundance and diversity. We here additionally investigated shifts in trophic niches of Collembola and Oribatida as indicated by stable isotope analysis (13C and 15N). We simulated short-term summer drought by excluding 65% of the ambient precipitation in conventionally and organically managed winter wheat fields on the DOK trial in Switzerland. Stable isotope values suggest that plant litter and root exudates were the most important resources for Collembola (Isotoma caerulea, Isotomurus maculatus and Orchesella villosa) and older plant material and microorganisms for Oribatida (Scheloribates laevigatus and Tectocepheus sarekensis). Drought treatment and farming systems did not affect abundances of the studied species. However, isotope values of some species increased in organically managed fields indicating a higher proportion of microorganisms in their diet. Trophic niche size, a measure of both isotope values combined, decreased with drought and under organic farming in some species presumably due to favored use of plants as basal resource instead of algae and microorganisms. Overall, our results suggest that the flexible usage of resources may buffer effects of drought and management practices on the abundance of microarthropods in agricultural systems.

Disaster-induced migration types and patterns, drivers, and impact: A union-level study in Bangladesh

Environmental shocks like disasters are reported to induce migration in different parts of the world. Bangladesh has been witnessing migration across the years, but the underlying mechanism of disaster-induced migration needs to be explored and understood with changing climate conditions. The main objective of this study is to evaluate disaster-induced migration types and patterns, the auxiliary drivers and the perceived impact of migration. A semi-structured questionnaire survey was carried out with 155 Union-level key persons from five districts of Bangladesh, and collected qualitative data were thematically analyzed using NVivo. Irrespective of the type of disaster, the major spatial-temporal pattern of migration was perceived to be temporary domestic migration from rural to urban areas. Comparing the auxiliary drivers of migration revealed some common economic drivers. The comparison diagram also identifies several other drivers which are disaster-specific. For e.g., social, demographic, and physical drivers are perceived to drive migration in cyclone-affected areas, while environmental drivers (land degradation, scarcity of safe drinking water, changes in soil condition, etc.) are the primary drivers behind migration in saline-affected areas. Regarding impacts, though household economic status is perceived to get better post-migration, loss of traditions and cultural value, loss of social ties, and loss of security are identified as some of the negative impacts of disaster-induced migration. The current study emphasizes that a migration policy as an umbrella policy may mask the local challenges and community requirements and argues for the need of a disaster-specific migration policy that addresses disaster-induced challenges encountered by local communities.

Assessment of self-adjustment of tillage working bodies to soil conditions

Assessment of self-adjustment, that is, automatically adjusting parameters of tillage working bodies as a result of soil exposure, is an urgent task, since it is associated with the problem of developing energy-efficient tillage units. The purpose of the research is to assess the self-adjustment of typical and dynamic tillage working bodies to specific soil conditions during their functioning. The objects of research are a dynamic tillage working body with an energy-storage transmitting device and a typical tillage working body for continuous surface treatment of various soil types. The subject of research was the indicators of self-adjustment of tillage working bodies to soil conditions. During the research, methods of mathematical modeling, strain measurement of tillage working bodies, analysis and generalization of experimental data were used. The scientific novelty of the work is represented by the selected criteria for assessing the self-adjustment of working bodies and the patterns of their change from the movement speed. As criteria for assessing the self-adjustment of tillage working bodies, the following were selected: the coefficient of terradynamic resistance, the specific traction resistance per unit of its active frontal area, the number of degrees of freedom of the tillage working body and indicators for assessing the tillage quality. Based on the proposed evaluation criteria, it was experimentally established that the dynamic tillage working body developed by the authors with an energy-storage transmitting device is more efficient and adapted to changing soil conditions in comparison with a typical working body, which provides a reduction in traction resistance by an average of 20% and an increase in the degree of soil loosening by an average of 8.4-8.8% compared with typical working bodies.