Arable Plots Research Articles

Mitigation measures designed to reduce soil compaction decrease the surface runoff, soil erosion and phosphorus losses from tramlines in agricultural fields

AbstractThe use of tramlines or wheelings to carry out agricultural operations, such as spraying and fertilizer applications, is common across the world. They are often orientated up and down the slope and the soil that is driven on becomes compacted because of machinery weight transferring stress through the soil profile. This compaction leads to tramlines becoming conduits for water moving over the soil surface. Like water, sediment and phosphorus are also detached and transported. Reducing surface runoff and diffuse pollution losses from surface runoff associated with wheelings has received some research attention, but results are often difficult to interpret. This is because of the low number of replicates that are possible in agricultural landscapes, if the research is to be conducted at meaningful scales and to remain feasible. To address this, we utilize effect sizes and confidence intervals to analyse surface runoff and diffuse pollution data from a series of studies at five arable field sites, in the UK where surface runoff, sediment and phosphorus was collected from hillslope scale tramline plots utilizing the same methodology. In addition, we tested the impact of very flexible tyres, rotary harrows and a surface profiler roller on surface runoff and diffuse pollution loses. Although the monitoring period did not encompass widespread flood inducing storms, we demonstrate that the magnitude of the sediment and total phosphorus (TP) losses from the tramline plots across the study sites are significant in the UK context. Annual sediment losses from the study plots are in the order of 0.5–4.5 Mg ha−1 yr.−1 and consistent with the magnitudes of soil erosion in the UK. TP fluxes observed at the study plots, ranged between 0.8 and 3.9 kg ha−1 yr.−1, are consistent with the TP losses reported for surface runoff from arable plots in the UK. By utilizing effect size analysis, we demonstrate the significant impact of tramline mitigation on surface runoff and diffuse pollution losses. The rotary harrow performed best overall, and the combination of the rotary harrow and the very flexible tyre was superior to all other methods. This was the case for all treatments apart from some, where the surface profiler performed well in reducing sediment fluxes. Our work supports the need for incorporating tramline management measures into soil management strategies for arable landscapes and provides evidence for policymakers developing measures for agri‐environmental schemes.

Early Mapping Method for Different Planting Types of Rice Based on Planet and Sentinel-2 Satellite Images

In Northeast China, transplanted rice cultivation has been adopted to extend the rice growing season and boost yields, responding to the limitations of the cumulative temperature zone and high food demand. However, direct-seeded rice offers advantages in water conservation and labour efficiency. The precise and timely monitoring of the distribution of different rice planting types is key to ensuring food security and promoting sustainable regional development. This study explores the feasibility of mapping various rice planting types using only early-stage satellite data from the rice growing season. We focused on Daxing Farm in Fujin City, Jiamusi City, Heilongjiang Province, for cropland plot extraction using Planet satellite imagery. Utilizing Sentinel-2 satellite imagery, we analysed the differences in rice’s modified normalized difference water index (MNDWI) during specific phenological periods. A multitemporal Gaussian mixture model (GMM) was developed, integrated with the maximum expectation algorithm, to produce binarized classification outcomes. These results were employed to detect surface changes and map the corresponding rice cultivation types. The probability of various rice cultivation types within arable plots was quantified, yielding a plot-level rice-cultivation-type mapping product. The mapping achieved an overall accuracy of 91.46% in classifying rice planting types, with a Kappa coefficient of 0.89. The area extraction based on arable land parcels showed a higher R2 by 0.1109 compared to pixel-based area extraction and a lower RMSE by 0.468, indicating more accurate results aligned with real statistics and surveys, thus validating our study’s method. This approach, not requiring labelled samples or many predefined parameters, offers a new method for rapid and feasible mapping, especially suitable for direct-seeded rice areas in Northeast China. It fills the gap in mapping rice distribution for different planting types, supporting water management in rice fields and policies for planting-method changes.

Assessing and geostatistical mapping of metal contamination in the polar arable plot (Yamal-Nenets Autonomous District, Russia)

Assessing and geostatistical mapping of metal contamination in the polar arable plot (Yamal-Nenets Autonomous District, Russia)

Assessment and Spatial Modelling of Agrochernozem Properties for Reclamation Measurements

Traditional land-use systems can be modified under the conditions of climate change. Higher air temperatures and loss of productive soil moisture lead to reduced crop yields. Irrigation is a possible solution to these problems. However, intense irrigation may have contributed to land degradation. This research assessed the ameliorative potential of soil and produced large-scale digital maps of soil properties for arable plot planning for the construction and operation of irrigation systems. Our research was carried out in the southern forest–steppe zone (Southern Ural, Russia). The soil cover of the site is represented by agrochernozem soils (Luvic Chernozem). We examined the morphological, physicochemical and agrochemical properties of the soil, as well as its heavy metal contents. The random forest (RF) non-linear approach was used to estimate the spatial distribution of the properties and produce maps. We found that soils were characterized by high organic carbon content (SOC) and neutral acidity and were well supplied with nitrogen and potassium concentrations. The agrochernozem was characterized by favorable water–physical properties and showed good values for water infiltration and moisture categories. The contents of heavy metals (lead, cadmium, mercury, cobalt, zinc and copper) did not exceed permissible levels. The soil quality rating interpretation confirms that these soils have high potential fertility and are convenient for irrigation activities. The spatial distribution of soil properties according to the generated maps were not homogeneous. The results showed that remote sensing covariates were the most critical variables in explaining soil properties variability. Our findings may be useful for developing reclamation strategies for similar soils that can restore soil health and improve crop productivity.

Fenced open-fields in mixed-farming systems: spatial organisation and cooperation in southern Sweden during the seventeenth century

The organisation of fields and fences in agriculture that emerged during the Middle Ages and the early modern period was a complex system that combined individual ownership of and communal practices in arable land, meadows and pastures. It was adapted for small and mid-size family-based farming and was a different way to organise agriculture than the medieval estates (demesnes) and the larger coherent fields of the eighteenth century and onwards. The past decade of research in historical geography and economic history has highlighted the origin of this system, which is often referred to as the open-field system; it was open in the sense that it promoted communal farming of primarily arable land. This pre-modern farming system was, however, in many areas a physically closed landscape – a landscape where fences stood out as significant elements. This article investigates the use of fences in a part of early modern western Sweden. The empirical base is a reconstruction of fence-organisations from detailed large-scale maps dating from the mid-seventeenth century. Using historical maps, this study focuses on the collaboration and interaction among farms and settlements. We argue that the open-field system cannot be fully understood without regard to an in-depth analysis of the fences and the institutions holding the complex collaboration together. The occurrence or absence of fences in relation to open-fields involves several questions: What are the characteristics of the fences in the farming systems known as open-field? What can be said about the spatial distributions and connections between the settlements sharing the same open-field? Can agrarian landscapes where fences were prominent elements be considered open-field? The results show that fences appear to be a key factor in understanding settlement patterns and open-fields in Scandinavian regions. A large number of fences created small fenced open-fields. Moreover, the divisions of the arable plots had less importance in the creation of open-fields, which included arable land, meadows and pastures. Instead, cross-settlement collaborations and arrangements are central for the open-fields in the study region. The regional differences within the open-field system provide an understanding of the preconditions and organisation of mixed farming, which combined small-scale arable land cultivation and large-scale pastures.

Conventional Tillage Effects on the Physico-Chemical Properties and Organic Matter of Chernozems Using 13C-NMR Spectroscopy

In this study, we examined the influence of long-term conventional tillage on the water-physical, chemical properties, and composition of the organic matter of chernozems. The study has been conducted on an arable plot subjected to water and wind erosion in the Pre-Ural steppe zone (Republic of Bashkortostan, Russia). Soil samples were collected from non-eroded and eroded arable plots as well as from an adjacent pristine forest windbreak. Key structural fragments of soil organic matter under different land use types were identified and quantified using 13C-NMR spectroscopy. The results showed that the water-physical properties deteriorated in agrochernozems: the number of valuable soil aggregates decreased and the soil bulk density increased, which may limit the growth of crops. The soil organic matter content for the different samples varied in the following direction: arable non-eroded > forest windbreak > arable eroded. It has been found that long-term plowing by conventional methods decreases aliphatic and increases aromatic structures in soils. As a result of the reduced inputs of plant residues, the processes of humification slowed down compared to unplowed soils. To increase soil fertility and carbon sequestration potential, it is necessary to stop degradation processes and implement conservation tillage practices.

On optimizing the deployment of an internet of things sensor network for soil and crop monitoring on arable plots

One of the main stream of digitalization in agriculture is the introduction of Internet of Things technologies, which is expressed in the creation and use of specialized sensors that are placed in the fields. The placement of such sensors within agricultural plot should make it possible to characterize all the microvariability of soil fertility parameters in the field. That is, their number and spatial location should be optimal, on the one hand, in terms of costs of their acquisition and operation, and, on the other hand, in terms of accuracy of interpolation of data obtained with their help to the entire plot. It has been shown that the use of crop condition maps obtained on the basis of satellite data and the separation based on them of management zones can lead to significant errors in the interpolation of monitoring results, obtained in separate points, on the whole plot. An approach for optimization of sensor placement is proposed based on the use of soil fertility mapping, which is the result of refinement, updating and clarification of traditionally drawn soil maps on the basis of high spatial resolution remote sensing data. The possibilities of using the approach are demonstrated by the example of a test plot in Leningrad region of Russia.

Fermentation of Whole Grain Sorghum (Sorghum bicolor (L.) Moench) with Different Dry Matter Concentrations: Effect on the Apparent Total Tract Digestibility of Energy, Crude Nutrients and Minerals in Growing Pigs.

Simple SummaryDue to climate change and pests as result of maize monoculture, the need of diversification of crop rotation forces researchers to look for alternative grains for animal nutrition. Furthermore, grain fermentation may increase the nutritional value of feed and, simultaneously, decrease costs of feed conservation because the necessity for grain drying and associated energy costs are reduced. In this context, the cultivation and integration of early harvested and fermented sorghum grain in pig diets might be an interesting strategy for the substitution of maize. Therefore, we tested the nutritional value of three varieties of fermented sorghum grains with gradual differences in total dry matter, in a Latin-Square experiment comprising growing pigs. Results indicated there is a potential for improving the nutrient digestibility of sorghum-based pig diets by using early harvested and fermented whole sorghum grain with lower dry matter concentration. Especially the need for inorganic phosphorus supplementation and, hence, the fecal phosphorus emissions were significantly reduced.This study investigated the effects of sorghum ensiled as whole grains with different dry matter concentrations on the apparent total tract digestibility (ATTD) of energy, crude nutrients and minerals in growing pigs. Whole grain sorghum batches with varying dry matter (DM) concentrations of 701 (S1), 738 (S2) and 809 g kg−1 (S3) due to different dates of harvest from the same arable plot, were stored in air-tight kegs (6 L) for 6 months to ensure complete fermentation. Subsequently, 9 crossbred barrows (34.6 ± 1.8 kg; (Duroc x Landrace) × Piétrain)) were used in a 3 × 3 Latin square feeding experiment. Diets were based on the respective sorghum grain silage and were supplemented with additional amino acids, minerals and vitamins to meet or exceed published feeding recommendations for growing pigs. The ATTD of gross energy, dry matter, organic matter, nitrogen-free extracts, and crude ash were higher in S1 compared to S3 treatments (p ≤ 0.05), while S2 was intermediate. Pigs fed S1 showed significantly higher ATTD of phosphorus (P) compared to all other groups while ATTD of calcium was unaffected irrespective of the feeding regime. In conclusion, growing pigs used whole grain sorghum fermented with a DM concentration of 701 g kg−1 (S1) most efficiently. In particular, the addition of inorganic P could have been reduced by 0.39 g kg−1 DM when using this silage compared to the variant with the highest DM value (809 g kg−1).

Assessment of species diversity and distribution of woody species on selected plots in Olokemeji Forest Reserve, Ogun State, Nigeria

The Assessment of forest species composition and species diversity is essential in understanding the status of tree population and diversity for conservation purpose. Olokemeji forest reserve is situated in the lowland rain forest of south-western Nigeria and it occupies a total land area of 58.88 km2 . Six study plots of 50m2 each were randomly selected and designated as Frequently Burnt Plot 1, Frequently Burnt Plot 2, Harvested Plot, Unharvested Unburnt Plot, Arable Plot 1 and Arable Plot 2 for the purpose of assessment of species diversity and distribution of woody species. Seven species of trees were identified belonging to five families. One hundred and eighty two stands were enumerated, with Unharvested Unburnt Plot having the highest number of trees at 50. The dominance index for the woody flora was 1 in Frequently Burnt Plot 1 and 2 as well as Arable Plot 1 and 2 except for the Harvested Plot that had the lowest (0.29) while the Unharvested Unburnt Plot had 0.75. Highest species richness was recorded at the Harvested Plot at 0.71. The species diversity in Harvested Plot was low (1.54), while it was extremely low in Unharvested Unburnt Plot (0.43). Evenness index was lowest in the Unharvested Unburnt Plot at 0.43. Tectona grandis had the highest relative importance value in the Frequently Burnt Plot 1. The low species richness and species diversity is a direct indication of anthropogenic interference in the study plots and the forest reserve; this requires urgent mitigation to prevent a total loss of its structure and function as expected of a forest reserve.
 Keywords: Species, Diversity, Evenness, Anthropogenic, Forest, Dynamics

Study of thickness of humus profiles of gray forest and chernozem soils of different terms of agricultural use in landscape shrubs of the central forest-steppe

The article presents the results of a field study of the thickness of the humus profiles of gray forest soils and podzolized chernozems of dif-ferent terms of agricultural use of soil catens of broad-leaved-forest (background) and meadow-steppe areas of the Belgorod region. The work was carried out in the spring and summer period 2018-2019. The objects of the study were different-aged arable plots with the age of agricultural development of 100 and 160 years, respectively. The steepness of the surface on the plots did not exceed 5-60. It is established that the thickness of humus profile under the influence of agricultural cultivation during 60 years has decreased by 49 cm, at that on the slopes of northern exposition this index is more expressed (33 cm) than on the slopes of southern exposition (16 cm). It is possible, to note, that with increase of age of agricultural use on slopes of northern and southern expositions the greatest thickness of humus horizon is observed on anomalous soils (72 and 65 sm accordingly). Within the background catens the soil cover is homogeneous, the second humus horizon was observed in each of the studied transects.

Land use parameters ensuring sustainable development of agricultural producers taking into account characteristics of climatic zones and land quality

Land use parameters determine to a large extent not only the scale, but also the efficiency of agricultural production. The article gives a description of the size and other qualitative characteristics of land use resulting from the agrarian transformations. The area of arable land used, including rented and owned by agricultural organizations, is shown by natural agricultural zones and the region as a whole. Based on the analysis of the influence of the size of arable land on the farm, the bonitet score, the technological properties of arable plots and their remoteness from production centers on the productivity and efficiency of crop production, the parameters providing effective and sustainable development of the industry were substantiated. In general, the trend of greater efficiency of crop production with a large land use is confirmed. As a result of the analysis, the marginal parameters of land quality were determined (bonitet score, index of estimated costs of the distance from economic centers to arable land), ensuring efficient crop production. These data were obtained for all natural and agricultural zones of the region. The validity of the parameters is determined by the state of agricultural production and is recommended for the next 5 years. In the future, such an analysis should be repeated periodically. The parameters obtained as a result of the study are recommended for use in the management of agricultural production and land use. They allow one to determine the main priorities in the agricultural policy of the region, including objects of state and regional support for agricultural production.

Edaphic factors and plants influence denitrification in soils from a long-term arable experiment

Factors influencing production of greenhouse gases nitrous oxide (N2O) and nitrogen (N2) in arable soils include high nitrate, moisture and plants; we investigate how differences in the soil microbiome due to antecedent soil treatment additionally influence denitrification. Microbial communities, denitrification gene abundance and gas production in soils from tilled arable plots with contrasting fertilizer inputs (no N, mineral N, FYM) and regenerated woodland in the long-term Broadbalk field experiment were investigated. Soil was transferred to pots, kept bare or planted with wheat and after 6 weeks, transferred to sealed chambers with or without K15NO3 fertilizer for 4 days; N2O and N2 were measured daily. Concentrations of N2O were higher when fertilizer was added, lower in the presence of plants, whilst N2 increased over time and with plants. Prior soil treatment but not exposure to N-fertiliser or plants during the experiment influenced denitrification gene (nirK, nirS, nosZI, nosZII) relative abundance. Under our experimental conditions, denitrification generated mostly N2; N2O was around 2% of total gaseous N2 + N2O. Prior long-term soil management influenced the soil microbiome and abundance of denitrification genes. The production of N2O was driven by nitrate availability and N2 generation increased in the presence of plants.

Development of empirical models for analysis of subsoil agricultural parameters from resistivity measurement in a basement complex terrain

ABSTRACT Soil electrical resistivity measurements and soil properties determination were carried out at an arable plot located within the Federal University of Technology, Akure, Ondo State. This was with a view to establishing relationship between in-situ soil resistivity and selected topsoil properties in a typical basement complex environment. Electrical Resistivity was measured from the soil surface at 0 to 50 cm soil depths using Wenner Array. Electrode spacing of 130 cm (1.3 m) was utilized. Soil samples were collected to a depth of 50 cm at the mid points of 2 m by 2 m cell. These were analyzed for properties that include: moisture content, particle size analysis, Organic Matter (OM), pH and electrical conductivity. The regression analysis plots show that ER correlate significantly to soil properties, with coefficient of correlation of 0.90 for MC, 0.63 for SC, 0.74 for CC, 0.57 for OM, 0.94 for EC. Except for SC and PH that shows a non-significant correlation of 0.52 and 0.30 respectively. Validation of the derived empirical model gives a coefficient of correlation between the observed and predicted result as 0.94 for MC, 0.74 for OM, 0.93 for EC, 0.79 for SC, 0.94 for silt content, 0.52 for clay content and 0.48 for PH. The study concluded that electrical resistivity measurements could be used as a rapid tool for obtaining the selected topsoil properties.

Soil modification in a chronosequence of postagricultural ecosystems of the intrazonal lithogenic matrix (Arkhangelsk region, Russia)

Processes of soil self-restoration and soil modification in the chronosequence of postagricultural ecosystems located within the intrazonal (floodplain) soils of boreal forests were studied. Successional changes in ecological features of the floodplain meadow soil properties in the postagricultural period were considered. We used arable land plots (22 model fields) in the Northern Dvina River delta (Primorsky District, Arkhangelsk region, Northwestern Russia) that have been removed from agricultural practice for the past 50 years and are currently at the self-overgrowing stage. Primary/secondary floodplain meadows with natural floodplain soils were used as reference plots. Changes in soil profiles and chemical properties in an old-arable horizon were observed during the restoration of abandoned fields. Floodplain soils of the Northern Dvina River basin occupied 4.8% of the area. These soils were characterized by high fertility and were actively used in agricultural production in the past. Postagricultural ecosystems of the Northern Dvina River floodplain tended to form natural waterlogged soils to varying extents. Ecosystems were characterized by a short period of soil restoration. The soil restoration process was slower than the vegetation cover restoration process. Soil fertility of the arable horizon persisted for 20 years. A cost-effective return of floodplain meadow lands to agricultural production is feasible over a period of 40 years. Then, soils return to natural floodplain soils, whereby they become waterlogged and lose their fertility.

Aggregate stability of south Chilean volcanic ash soils – A combined XPS, contact angle, and surface charge analysis

Soils developed from volcanic ash deposits vary extremely in physical and chemical soil properties and are known to degrade easily through erosion or soil compaction, which limits intensive utilization. Our objective was to test if aggregate stability, AS, as a key factor for erodibility, can be assessed from surface parameters, namely particle wettability in terms of the solid–water contact angle, CA, and the specific surface charge, SSC. To relate wettability to the chemical composition of particle interfaces, the amount of polar and nonpolar carbon (C) species within the particle interface layer was assessed by X-ray photoelectron spectroscopy, XPS. Samples were taken from four locations in southern Chile (40° south) along a 120 km transect from the central volcano range to the coastal mountain region. Sites were different in stage of soil development and land use. Aggregates (8–12 mm) were sampled on forest, meadow or arable plots from upper top- and subsoil. To increase the natural range of SSC and CA, soil pH was modified by treatment with HCl and NH3 gas, respectively. Results showed a general trend of increasing AS with increasing soil development, i.e. decreasing bulk density and increasing clay and soil organic carbon, SOC, content. A clear relation was also found between CA and AS with a wide range of AS (about 9 to >90%) at CA < 35° and always high AS for CA > 35°. XPS analysis showed that CA was closely related to the amount of nonpolar C species. Interestingly, the relation between CA and AS was still consistent after pH variation (initial pH ≅ 6, modified to pH 2 to 9) which led to net changes in SSC from around 0 C g−1 (pH 6) to values between +10 and −8 C g−1, respectively. CA for negative SSC were still in the range from 0° to >90°, similar to untreated soil, whereas positive SSC reduced the maximum CA to <40°. Increasing or decreasing SSC caused higher AS, while the least stable aggregates were found at point of zero charge, PZC. XPS analysis showed that a relative increase in interfacial C content increased AS (r2 = 0.77) and CA (r2 = 0.98) significantly. Generally, CA was revealed to be a significant parameter that allows rapid assessment of the present status and possible modifications of AS for a wide range of environmental conditions.

Mountain Arable Land Abandonment (1968–2018) in the Romanian Carpathians: Environmental Conflicts and Sustainability Issues

The agricultural mountain landscape in the Romanian Carpathians follows the same change trend in other European mountains, from variety and individuality to simplification and uniformization. Our paper proposes two complementary case studies from the Southern Carpathians—Poiana Mărului and Fundata, representative areas for the entire Carpathian ecoregion. The research focuses on a remote sensing approach with Corona KH-4B (1968) and Planet Scope (2018) images at 2.0–3.0 m resolution used for mapping arable plots pattern and size change. Landscape transformation modelling is focused on four-hectare sampled grid for both case study areas, followed by a landscape metric analysis. Fundata area is the most transformed, where arable plots disappeared under the service-based economy pressure. Poiana Mărului shows an earlier stage of landscape transformation, where the arable land abandonment process is incipient. The spatial and statistical analysis and field survey confirmed that tourism changed the traditional agricultural landscape, generating potential environmental conflicts and indicating the sustainability degree.

Emission of Carbon Dioxide from the Dark Chestnut Soil in West Kazakhstan

The necessity of studying and assessing emissions of carbon dioxide from the agricultural soils is related to the important role played by the soil in their formation. Active release of carbon dioxide shows changes in the content of the organic matter in the soil and its biological activity. Carbon dioxide emissions can be influenced both by biotic and anthropogenic factors. Due to the negative effect of grazing and arable plots on the soil respiration, unequal emission of carbon dioxide is noted. The research was aimed at assessing the dynamics of carbon dioxide emissions from the dark-chestnut soil, depending on the nature of the soil use in agriculture. The studies for determining the carbon dioxide flow rate were performed according to the standard variant of the closed dynamic chamber method. The results of studying the content and emission of carbon dioxide from the dark-chestnut soil of the agricultural lands in Western Kazakhstan are shown. The content and reserves of humus in the 100 cm layer of the studied soils are low, and the soil is characterized by low humus content. The total annual flow of carbon dioxide from the virgin lands is higher than that from the arable lands but is less than that from the pastures.

Change of CO2 Emission in Dark Chestnut Soil of Transurals

The article presents data on carbon reserves of dark chestnut soil and describes the influence of agricultural land on CO2 emissions in the arid territory of the Ural region. According to the study, the largest carbon stock in the humus horizon was observed on virgin soil, the smallest - on arable land. Emission of carbon dioxide can be influenced by both biotic and anthropogenic factors. Due to the negative impact of pasture and arable plots on soil respiration, there has been noted a significant release of CO2 emissions.

Agriculture changes soil properties on the Galápagos Islands – two case studies

The Galápagos Islands have faced a huge rise in the number of inhabitants and tourists over recent decades. As a consequence, natural forest vegetation has been converted to arable land to meet the increasing demand for agricultural produce. However, studies on soils and soil use change in the Galápagos Islands are scarce. In this study, we assessed the impacts of agricultural land-use on the islands of Santa Cruz and San Cristóbal. The site on Santa Cruz was called El Cascajo (EC, Leptosol, 5 years after conversion to intensive agriculture) and that on the oldest island of the Galápagos archipelago, San Cristóbal, Cerro Verde (CV, Ferralsol, 15 years after conversion). At both sites, we compared arable soils to soils under forests within the adjacent Galápagos National Park, which had formed on the same parent materials. Several soil properties showed a significant impact of the arable use. Soil organic carbon (Corg) stocks were relatively high at both sites (between 94 ± 28 and 142 ± 10 Mg ha–1). At CV, the stocks were 25% lower in arable plots compared with natural forest, but the observed decrease at EC was non-significant. Many other parameters like total nitrogen and several Mehlich-III extractable nutrients were closely correlated with the changes in Corg. Microbial biomass carbon (Cmic) and dissolved organic carbon were significantly lower in arable plots compared with forest at both sites. At EC, Cmic/Corg dropped by a factor of 1.9. Changes in pH and the use of agrochemicals, evidenced by pesticide residues detected in the soil, might be a possible explanation. Ammonium-N decreased and nitrate-N increased tremendously in the arable plots on both islands. Our research shows that present agricultural practices have potential for improvements towards a more sustainable agricultural use of soil resources on the Galápagos Islands.

Структурный состав почв юго-востока Центрально-Черноземной зоны с различным характером использования (на примере почв Каменной степи)

The study of the structural state of chernozems with patterns of use was done at V.V. Dokuchaev Research Institute of Agriculture of the Central Black-Earth Zone in 2019. The study was done under the conditions of agrocenoses and undisturbed ecosystems. Soils of naturally preserved biocenosis were represented by ordinary chernozems (automorphic) or segregation chernozems, soils of arable land – ordinary chernozems (automorphic) or segregation agro-chernozems. The experimental plots of arable land with slope variants were represented by sections of slopes of the Eastern exposure with a slope of up to 3°. The soil cover of experimental arable plots was a combination of chernozems such as topsoil segregation, migration-micellar with a small part of zoogenic turbocharged soil. The soil structure was determined by the method of N.I. Savvinov. A significant reduction in the share of agronomically valuable aggregates in soils influenced to intensive agrogenic impacts was found. Confirmation of this phenomenon was a significant decrease of the coefficient of soil structure: 3.2 on arable land, 14.0 – on abandoned land. There was a threefold decrease in the amount of the soil aggregates under the conditions of agrogenic impacts in spite of there was the small amount of silty part of the soil aggregates. The meso-aggregates of soil with size from 2 to 5 mm were related to the most vulnerable component of soil agronomically valuable structure. There were the most noticeable decrease of the relative content of meso-aggregates of soil under agricultural impacts (along with lumpy particles).