Surface Soil Horizons Research Articles

The nature of the patchiness of the irrigated fields and the possibility of its recognition on space imagery

Different variants of the patchiness of irrigated fields as observed at the multispectral satellite imagery of Landsat-8 OLI (on the open soil surface and under the canopy of agricultural crops), were studied on the example of irrigated cropland of the Svetloyarsk irrigation system located in the Volgograd region. The area has a soil cover consisting of solonetz complexes of the dry steppe. The field studies were also performed. It was revealed that the patchiness of irrigated fields is mainly associated with secondary salinization or with a significant content of carbonates in the surface soil horizons. Patchiness is often accompanied by a significant decrease in yield due to the loss of crops. Since the patchiness of irrigated fields in the south of Russia has a different origin, the ground truth data are necessary for correct interpretation of remote sensing materials.

Influence of ecological and anthropogenic factors on soil transformation in recreational areas of Volgograd (Russia)

In this paper, we studied the soils of recreational areas of Volgograd within three research areas. The survey found that in research area I the soils spatial distribution is mainly represented by the following soil group according to WRB: Urbic Technosols, Urbic Technosols (Mollic) and Gleyic Terric Phaeozem (Mollic, Prototechnic). Buried soils are represented by Gleic Cambisols (Protocalcic). In research area II, among natural soils, the largest areas are occupied by Calcaric Fluvisols (Loamic, Technic, Protovertic), Calcaric Fluvisols (Arenic, Salic), and Gleyic Calcisols (Sodic, Protocalcic, Technic, Salic). The anthropogenic-transformed soils include Urbic Technosols, and Ekranic Technosols are under buildings and road surfaces. In research area III, the natural soils spatial distribution is homogeneous and mainly represented by Gleyic Cambic Calcisols (Protocalcic), Gleyic Cambisols (Protocalcic, Prototechnic), and Calcaric Colluvic Regosols (Arenic, Prototechnic) in the bottoms of small flat-bottom valleys. In irrigation sites occur Urbic Technosols, and on hiking trails – Gleyic Cambisols (Prototechnic). Despite the presence of reclaimed horizons with a high content of phosphorus in the soils (average concentration of 82 mg kg−1), none of the profiles revealed Hortic horizon, but only some of its properties (colour, horizon thickness, zoogenic activity). The thickness of urbic-stratifying layer (Au) varies in a wide range from 10 to 135 cm, and the thickness of reclaimed horizons (A) also varies from 10 to 48 cm. The bulk density in Au horizons is 1.4 g cm−3, in the reclaimed horizons (A) – 1.39 g cm−3. The content of soil carbon in soil surface horizons varies from 0.85% to 4.58% in urbic horizons, and to 1.49% in reclaimed horizons. Chemical analysis of urbic (Au) and reclaimed (A) horizons revealed a low content of easily soluble salts (0.16%) and carbonates (1.5% and 1.7%, respectively).

Changes of Soil Organic Carbon after Wildfire in a Boreal Forest, Northeast CHINA

Boreal forests with high carbon sequestration capacity play a crucial role in mitigating global climate change. Addressing dynamic changes of soil organic carbon (SOC) after wildfire helps in understanding carbon cycling. The objective of this study is to investigate changes in soil organic carbon after wildfires in a boreal forest. The post-fire soil chronosequence after 3 months, 17 years, and 25 years within a boreal forest was used to examine dynamic and stable SOC after wildfire at the decadal scale. Soils in genetic horizons were sampled and analyzed for dynamic and stable SOC, including water stable aggregates (WSA), WSA associated organic carbon (WSA-SOC), soil heavy fractions (HF) associated organic carbon (HF-SOC), and soil total organic carbon (TOC). The TOC and WSA-SOC content of the A horizon was the greatest in the control site. There was no significant difference for TOC between burned and unburned deep BC horizons. The TOC for the A and B horizons at the 17-year-old site was significantly lower compared to the other sites. TOC did not recover to the pre-fire levels (control site) in any of the burned areas. The lowest WSA was found in the A and B horizons of the 3-month-old site. The WSA at the 25-year-old site was higher compared to the 17-year-old site. WSA increased with time following fire, but the recovery rate differed among different sites. The lowest concentration of WSA-SOC for the A horizon occurred at the 17-year-old site, and no significant difference was observed between B and BC horizons. The HF content for the A horizon was the greatest at the 3-month-old site. There was no significant difference in HF-SOC between B and BC horizons in all sites. TOC and stable SOC (HF and WSA) increased over time in species-dominance relay stand areas, while self-replacement stands areas showed the opposite. The results indicate that overall, the ability of soil to sequester carbon decreased after wildfire disturbances. Stable SOC accumulated more in areas where species-dominance relay succession occurred compared to the self-replacement stands. These disturbances were more pronounced for surface soil horizons. This study provides a quantitative assessment of SOC changes after wildfires that are useful for forest management and modeling forecasts of SOC stocks, especially in boreal forests.

Degradation of Arable Soils in Central Yakutia: Negative Consequences of Global Warming for Yedoma Landscapes

Global warming, which is especially intensive (up to 0.08°C yr−1) in permafrost area of Central Yakutia, has dramatic consequences for scarce arable land resources in this region. In Yedoma landscapes, intense permafrost thawing on arable fields unprotected by forest vegetation transforms the surface microtopography with the formation of residual thermokarst mounds (byllars) of 6–10 m in diameter surrounded by a polygonal network of hollows of 0.3–1.5 m in depth above melting ice wedges. This process also takes place on former croplands abandoned in the recent decades because of socioeconomic reasons. It is accompanied by a significant transformation of the previously highly likely homogeneous soil cover composed of Cambic Turbic Cryosols (Sodic) into differentiated complexes of permafrost-affected Stagnic Cambisols or Calcic Solonetzes (Turbic) on the mounds and Calcic Stagnic Solonetzes (Turbic) in the microlows. Surface soil horizons on the mounds have a strongly to very strongly alkaline reaction (pH 8.5–9.5) and low (<2%) organic carbon content; a wavy line of effervescence is found at a depth of 15–30 cm. Soils in the microlows have a close to neutral reaction in the upper horizons (pH 6.2–7.5); higher organic carbon content (2–3%); more pronounced textural differentiation of the profile with the formation of typical natric Btn and, in some cases, overlying eluvial E horizons; deeper (50–60 cm) line of effervescence; and clear stagnic features in the lower part of the profile. In the case of shallow embedding by ice wedge, the lowermost part of the soil in the microlow is characterized by the low bulk density (1.04 g cm−3) because of the appearance of hollows after thawing of the ice-rich transient layer and melting of the top of ice wedges. This may be indicative of the further soil subsidence in the future and the appearance of initial thermokarst lakes (dyuedya) within the Yedoma terrain with its transformation into the alas type of landscape. Rapid thermokarst-driven development of microtopography followed by differentiation of the soil cover with increasing soil alkalinity on the microhighs and soil textural differentiation and overmoistening of deep layers in the microlows prevents the return of abandoned arable land to agriculture in Yedoma landscapes.

Slope aspect and altitude effect on selected soil organic matter characteristics in Beskid Mountains forest soils

Abstract In the era of dynamic climate change, it is important to have knowledge on the interactions between climatic factors and processes occurring in the soil environment. The present study aimed to determine how slope aspect and altitude above sea level influence carbon and nitrogen accumulation and dehydrogenases activity of forest soils. The study was conducted in the Beskid Żywiecki in the south-facing part of Poland. Soils of the same texture, with similar vegetation species composition, in different altitude variants (600, 800, 1000 and 1200 m above sea level) and different north-facing and south-facing slope aspect were selected for the study. For each height and slope aspect variant, samples were collected from the surface horizons of soils for further analyses. The basic chemical properties and dehydrogenases activity of the soil samples were determined. Carbon and nitrogen stocks in the surface horizons of the soils were calculated. The analyses confirmed the influence of location conditions on the carbon and nitrogen stocks in mountain forest soils. The stock of carbon and nitrogen increased with the height up to 1000 m a.s.l. In the soils at the highest altitude, the reserve of carbon and nitrogen decreased regardless of the slope aspect variant. There were no statistically significant differences in carbon and nitrogen stocks between slope aspect variant. The highest dehydrogenases activity was associated with the organic horizons of the soils at the lowest altitude in height gradient. In our study, higher dehydrogenases activity was observed in the north-facing slope soils, and this finding can be explained by more stable thermal conditions.

Changing controls of soil water retention in an alpine catchment: Integrating sedimentological and pedological processes

Soil’s hydrological and ecological functions depend largely on soil water retention, which is affected by both structural and compositional soil properties. Studies have shown that alpine soils derived from sediments with different origins in the northeast Qinghai-Tibetan Plateau differ significantly in terms of particle size distribution, bulk density and soil organic carbon content. However, the variation pattern and its drivers of soil water retention in this region remain unclear. In this study, soil water retention characteristics (saturated soil water capacity, field capacity, wilting point and plant available water capacity) from different geomorphic settings (i.e., hillslopes, alluvial fans and floodplains) of an alpine catchment in the western part of the Qilian Mountains were analyzed in relation to sediment types and soil properties. Results show that soil water retention varies significantly with sediment types. Soils with an aeolian origin have a higher capacity to retain water compared with soils developed on fluvial sediments. Variations in soil water retention are mainly controlled by particle size distribution for fluvial sediments and by soil organic carbon content for aeolian sediments. The accumulation of soil organic carbon enhances plant available water capacity for sandy fluvial sediments but not for silty fluvial and aeolian sediments. The critical eco-hydrological functions of the mattic surface soil horizon in relation to water retention, runoff regulation and erosion control were highlighted for the alpine ecosystems. By deciphering sedimentological and pedological controls of soil water retention, this study improves the understanding of the evolution and functioning of alpine soils, which has further implications for other sedimentary ecosystems.

Bioenergy production effects on SOM with depth of loblolly pine forests on Paleaquults in southeastern USA

Managed loblolly pine (P. taeda L.) forests comprise a major land-use across the “wood basket” of the southeastern US. Lower coastal plain loblolly pine forests can enhance carbon (C) storage in fast-growing vegetation and soils, representing a significant opportunity to manage these forests for improved soil health through an understanding of soil C and nitrogen (N) storage. Furthermore, these forests have unrealized potential to produce biomass for emerging bioenergy markets. Despite this, very little is known about how intensified management (herbaceous bioenergy production) of these forests influences short-term soil organic C (SOC) and soil organic N (SON) pools in surface and subsurface soil horizons. The field site was located in the Lower Coastal Plain of North Carolina, USA in which trees were planted in bedded (e.g., raised) rows (bed) and intercropped with or without switchgrass (P. virgatum L.) between the bedded rows of trees (interbed). Soils were collected from four depths (0–5, 5–15, 15–30, and 30–45 cm) and two locations (bed and interbed regions) and fractionated into light and heavy mineral-associated SOC and SON pools using a sequential density fractionation technique. Bulk soil SOC and SON concentration as well as C:N ratio decreased with depth for both treatments, while 15N became enriched. Free and occluded lighter fractions (< 1.65 g cm−3) had higher SOC and SON concentration (~45% C and ~ 1.15% N) compared to medium (1.65–2.00 g cm−3) and heavy (> 2.00 g cm−3) fractions. At the 0–5 cm depth in interbeds, SOC and SON were concentrated in the free light fraction (~45%), but transitioned to being concentrated in the heaviest mineral-associated fraction at the 15–30 (~55%) and 30–45 (~70%) cm depth. The 15N analysis of density fractions indicated progressive enrichment with increasing density, suggesting increasing incorporation of microbially-derived products into stable mineral-associated soil organic matter (SOM) pools. In the pine-switchgrass treatment, SOC and SON concentrations were higher in the light and medium fractions in beds and interbeds compared to the pine only treatment, particularly at the 30–45 cm depth. The C:N ratio in the pine-switchgrass treatment was higher compared to the pine only treatment indicating inputs of new plant-derived organic matter. Furthermore, the δ13C stable isotope signature was enriched in both the occluded light fraction (1.65 g cm−3) and the mineral-associated fraction (1.65–1.85 g cm−3). Our results suggest that switchgrass intercropping is contributing to the early buildup of SOM in particulate and mineral-associated SOM pools possibly through additions of new root-derived organic matter and the positive effect on soil microbial activity through priming of microbes.

Geochemical Distribution of Some Heavy Metals in Agricultural Soil and Their Environmental Impacts in Kirkuk, Northern Iraq

This study is based on agricultural soil samples which are collected along three traverses (A, B, C), near the gypsum quarries located near the village of Bajwan north of Kirkuk city, to conduct a geochemical analysis and determining some heavy elements (Co, Cr, Ni, Cu, Sr, Pb, Cd) levels in the surface and subsurface soil horizons, and to indicate the potential sources of contamination with these elements. Accordingly, 30 samples were collected (six samples from travers A, five samples from travers B, and four samples from travers C) from the soil for each of the surface and subsurface levels. The results showed that the average concentrations of most studied elements increased in the subsurface soil compared to the surface soil, as a result of the influence of different geological and environmental conditions on the distribution of these elements in different soil horizons. The concentrations of the studied elements (Co, Ni, Cd) are more than their natural concentrations when compared to the natural abundance of these elements in the earth's crust, which indicates an increase in the concentration of these elements in the soil as a result of the proximity of the study area to the oil industries activities, causing the emission of high concentrations of heavy elements. As well as the traffic density of vehicles, causing the release of high concentrations of some elements. The geo accumulation factor (Igeo) indicates that most of the soil samples within different horizons of most of the heavy elements are uncontaminated to moderately contaminated, and moderately contaminated for cadmium. Also, by calculating the RI and the environmental risk factor (Er), it was found that the relative content of cadmium in soil samples recorded a considerable potential ecological risk to a high potential ecological risk. This indicates high affinity of cadmium in the soil as its infiltration into the subsurface layers.

Impact of soil temperature on fruit species within climate change scenarios

Climate change, with its consequent increase in temperatures and precipitation, has significant impacts on soil surface horizons, affecting the establishment, development, and production of crops and food security and safety. Solar radiation influences the thermals of Earth's surface. Apart from radiation, the effects of soil temperature (STe) are specific to fruit species and are mainly modified by humidity, soil cover and air temperature. Increasing the STe within an optimal range promotes the growth of roots and plants and increases the absorption of water and nutrients, photosynthesis, transpiration, efficient use of water and microbial processes. These effects have been demonstrated in several studies on fruit trees and on grape vines, citrus, cape gooseberries, Annonaceae, avocados, olives and prickly pears. However, apart from these positive results, an increased STe as the result of global warming can generate water stress and in turn affect the yield and quality of fruit trees. In terms of effects from cultural practices, mulching with black or blue plastic can increase the soil temperature, and white or silver plastic decreases it. When compared to air temperature, increases in STe in the plants physiology and climate impact studies have been little studied. Therefore, this review aimed to make significant contributions to facilitate decision-making with the goal of reducing the effects of global warming, especially on fruit trees.

Carbon Storage along with Soil Profile: An Example of Soil Chronosequence from the Fluvial Terraces on the Pakua Tableland, Taiwan

A well-dated soil chronosequence may allow exploration of the accumulation of soil carbon over time. There are multiple levels of river terraces on the Pakua tableland in Central Taiwan. Unlike many of the reddish or lateritic soils in Taiwan, these soils were recently dated, with absolute ages in the range of 19–400 kyr. This information allowed us to develop an ideal soil chronosequence, with time constraints, through which it is possible to explore soil organic carbon (SOC) storage and its changes over time. In this study, we attempted to establish an SOC time series, and to give an estimate of long-term accumulation of the SOC storage in the red soils of Taiwan. The data on these soils used in this study were taken from the soil profiles presented in our previous studies. Two additional soil profiles were sampled for those soils for which data were not available from the previous studies. The total carbon stock (TCS) for each soil profile was measured and assessed based on the depth categories of 0–30, 30–50, and 50–100 cm. Weighted carbon stock (WCS) measurements were further derived by the total thickness of the soil profile, for better comparison. The overall carbon stocks of the soils in the Pakua tableland were in the range of 2.8–3.2 Tg for TCS and WCS, respectively. In addition, the SOC tended to be highest in the surface soil horizons and decreased with the soil depth. The continuous pattern of the carbon content, in terms of its vertical distribution, was considered in terms of a negative exponential function, which showed that the SOC was highest in the shallowest soil layers and decreased rapidly with the soil depth. This trend was mitigated at a depth of 50–100 cm, which approached a fixed value, denoted as the carbon sequestration value (CSV), below a certain depth. We show here that the values of the CSV, as approximated by exponential fitting, are closely related to soil age. The CSV linearly decreases with age. These findings point to the potential of using carbon storage for chronometric applications.

Nitrogen limitation of microbial activity in alpine tundra soils along an environmental gradient: Intra-seasonal variations and effect of rising temperature

Alpine tundra ecosystems exhibit one of the most limited availabilities of nitrogen. Furthermore, climate change may potentially stimulate not only soil organic matter decomposition, but also N mineralization; therefore, a better understanding of the response of microorganisms to increasing N availability is crucial for evaluating soil C cycling under warmer climate scenarios. In this study, we suggested that the degree of N limitation of microbial activity in the surface and subsurface soil horizons of a N-poor dwarf-shrub heath (DSH) and an N-rich graminoid meadow (GM) during a single active growing season. We conducted three series of laboratory incubations under natural (+10 °C) and high (+20 °C) temperatures with soil samples collected at the beginning, peak, and end of the growing season to examine the effects of rising temperature and intra-seasonal variations on the N limitation of microbial activity. We measured the contents of microbial C and N, microbial respiration, and the potential activity of peroxidase and β-1.4-glucosidase (enzymes that play a key role in the SOM turnover processes). It was found that the N limitation of microorganism activity could be dynamic and demonstrate temporal (depending on the season) and spatial (depending on the soil horizon) variations. The results disputed the universality of previous conclusions about the high degree of N limitation of microorganisms in alpine tundra soils, thereby suggesting that N is not always a limiting factor for microbial activity, even in the N-poor DSH. We found that warming could increase the N limitation of microorganisms, even in the N-rich GM soil, thereby limiting the effect of warming on the mineralization of soil organic matter. These data demonstrate the importance of further understanding the internal feedback mechanisms that control soil organic matter mineralization and microbial activity for accurately predicting the effects of global climate change in the Arctic.

Indicators of the state of forage ecosystems arid and semi-arid territories of Siberia and Kazakhstan

Science-based management of forage ecosystems of arid and semi-arid territories and the fight against their degradation, carried out on the basis of systematic monitoring, assessment and accounting of their state and dynamics, are becoming actual state problems in Russia and Kazakhstan. As a result of studying, evaluating and agro-landscape-ecological zoning of territories of Siberia and Kazakhstan, creating databases of land resources and natural forage lands, using literary and stock data, the authors developed indicators of the state of forage ecosystems of arid and semi-arid territories. One of the most important ways to improve the effectiveness of assessments of the state and dynamics of degradation of forage ecosystems, as well as the most accurate diagnosis of negative processes is to solve the problem of creating and using a system of geobotanical and soil indicators of degradation of forage ecosystems. The full assessment of the state and development of the process of degradation of forage ecosystems can only be provided by using the entire system of indicators compiled on the basis of a combination of a number of main indicators of forage ecosystems. Geobotanical indicators of forage ecosystems include the following main indicators: change of plant communities, degradation of pastures, projective cover of indigenous and ruderal vegetation, productivity of natural pastures, etc. Soil indicators include: the area of allotments disturbed by erosion, the degree of destruction of surface soil horizons by erosion, the intensity of erosion, etc.

Influence of edaphic and management factors on soils aggregates stability under no-tillage in Mollisols and Vertisols of the Pampa Region, Argentina

In the highly fertile and productive soils of the Pampa Region of Argentina, constraints on soil water regime as a consequence of the decline in aggregates stability and the development of platy structures, are observed. Most of agricultural plots in this region, even under no tillage, are subjected to simplification of crop sequences (low cropping intensity) with predominance of soybean. On the contrary, some farmers are intensifying the crops sequence to avoid soil degradation and equilibrate economical incomes. The aim of this work was to evaluate the effects of intrinsic soil factors and of cropping intensity on aggregates stability in the surface horizon of the main soils in this region. Three Mollisols (an Entic Haplustoll and two Typic Argiudolls) and a Vertisol (Hapludert) located across a west-east transect in the northern part of the Argentinean Pampas were selected for this study. In each site two management treatments under no-till (GAP: Good Agricultural Practices –high cropping intensity- and PAP: Poor Agricultural Practices –low cropping intensity-) and a soil without cultivation as a reference (NE: Natural Environment) were compared. In each treatment, aggregates destruction mechanisms were assessed by Le Bissonnais (1996) tests: slaking, microcraking and cohesion loss. Mollisols showed higher aggregates stability than the Vertisol. Differences on aggregates stability depended on management variables and on organic carbon contents in the Mollisols and on both clay content-clay type in the Vertisol, revealing a strong relationship of aggregation mechanisms with soils taxonomic order. In the Mollisols, the labile coarse particulate organic carbon fraction (POCc) determined the shifts on slaking and overall aggregates stability rather than other carbon fractions. In the soils studied, aggregates stability was linked mainly to management variables, best reflected by the cropping intensity index (CI). More intensive agricultural managements (GAP treatments) in Mollisols and Vertisol, resulted in an enhancement of aggregates stability; however, this relationship was stronger in the Mollisols. Surface horizons from both soil orders evidenced a high soil fragility related to slaking process (FW10s and FW tests). Thus, FW test was the best test to discriminate between management treatments. The results obtained in this work allow, on the one hand, to understand the stabilization mechanisms of the structure in the surface horizon of the main Pampas soils and, on the other hand, to highlight the effect of different NT management practice on soil aggregate stability, which highly affects soil health and the sustainability of agricultural systems.

The conservation agriculture in northwest of Morocco (Merchouch area): The impact of no-till systems on physical properties of soils in semi-arid climate

Conservation agriculture (CA) is characterized by three principles: minimum tillage, even the total absence of tillage in the case of direct seeding (NT), permanent soil cover by mulch, and diversification of crops. Its main objective is to control soil degradation by conserving the physical and biological properties and fertility of the soil, which leads to an improvement in productivity, while preserving the environment. Conventional tillage (CT) used in the arid and semi-arid environments of Morocco (particularly in the study site area of Merchouch) compromise the productivity of established crops in these regions. The work presented consists in the study of the impact of NT on the physico-chemical properties of the soil, especially organic matter (SOM), bulk density (BD), soil moisture (θg), and structural stability (SS) in semi-arid zones. The results show that the use of the NT system positively influences the accumulation of SOM, especially at the soil surface horizon (0-5cm). Concerning θg, there is a significant difference between the two treatments (NT and CT) at the average of the three depths and especially at the horizon 20-40 cm so NT increases the water retention capacity. This study also shows that the mean weight diameter (MWD) of the 3 tests (water, ethanol, and rehumectation) is higher for NT compared to CT. This shows that no-till helped to build a good soil structure over time, which is highly desirable for improving agricultural productivity and conserving natural resources, especially water.

Osobine i nivo podzemne vode Humoglej zemljišta južne Bačke

The paper examines hydromorphic soils from the class of gley soils, soil type humogley. The examined soils are located in the protected part of the inundation of the middle course of the Danube. According to the chemical properties of the examined soils, the pH value ranges from 7,64 to 8,15 on average, and with depth there is an increase in alkalinity. The total salts of the examined soils had increased values in the humus horizon and ranged from 0,06 to 0,09%. The texture classes of the humus horizon of these soils are: clay loam to sandy clay loam, while the lower sub-horizons of the gley are textural classes of sandy loam, loamy sand and sand. The influence of the Danube water level on the groundwater level results in high correlation coefficients, which range from 0,67 to 0,88. The groundwater in these soils had the highest level from 28 cm to 70 cm depth, and the lowest level was from 110 to 175 cm deep. The amplitude of groundwater variation during the year in the examined humogley soils ranges from 66 to 132 cm. Groundwater quality classes according to U.S. Salinity Laboratories are unfavorable and range from C3S1 to C4S1, ie salt to very salty water with low sodium content, and according to the FAO classification the water quality is such that there is a moderate need for restriction. High groundwater level above the critical level, as well as watering the soil with water of this quality can have an impact on salinization of the surface horizon of humogley soil of the examined area.

The influence of different methods of soil processing on the microbial communities composition

Modern agriculture faces the challenge of soil degradation due to improper land use and the development of erosion processes. Plowing technology profoundly transforms the surface soil horizon and makes it vulnerable to such negative processes. One of the technologies that reduce agricultural practices’ negative impact on the soil is direct sowing, which is much more environmentally friendly than disking and plowing. In this work, the influence of different tillage technologies on the soil microbial community structure was studied. It was found that the number of cellulolytic, ammonifying bacteria, actinomycetes, and soil fungi was significantly higher when using direct sowing technology compared to plowing. The intensity of mineralization processes was lower than during plowing, which indicates a shift in the balance towards the accumulation of soil organic matter. Thus, the technology of direct sowing contributes to an increase in the soil biological activity and can be an effective method for restoring soil fertility.

К оценке гумусного состояния и ферментативной активности почв Дальневосточного морского заповедника

Indicators of humus state and catalase activity were determined in the soils of the Far Eastern marine reserve. The average humus content was exposed for the dark humus burozem and the dark humus soil, formed on buried burozem. The distribution of humus in the profile is estimated as gradually decreasing, the humus reserves in the 20 cm layer are characterized as very high and high. Variation of the typical humus composition and humification index differs in the studied soils. "Free" fractions predominate in the composition of humic acids, their proportion reaching high and very high values. The surface horizons of soils are characterized by poor and very poor catalase enrichment. The morphological shape of the profile and the parameters of the humus state of the studied soils of the far Eastern marine reserve confirm the previously obtained data on climate changes and ocean transgression in the South-Western part of the Pacific coast of the region in the Holocene.

دراسة التركيب المعدني لبعض ترب الجزيرة السورية

تهدف الدراسة إلى معرفة التركيب المعدنيّ لترب من الجزيرة السورية وتأثيره في بعض خصائص التربة الفيزيائيّة والكيمائيّة. تم تحضير مقطعين وأخذ ثلاثة عيّنات ترابية من كل مقطع حسب الآفاق، وتمت دراسة بعض الخصائص الفيزيائيّة والكيمائيّة بالإضافة إلى دراسة التركيب المعدنيّ لهذه الترب، وبينت نتائج دراسة التركيب المعدنيّ وجود مجموعة من المعادن الأوليّة وكانت أعلى نسبة لمعدن الكالسيت في الترب المدروسة، ويليه معدن الكوارتز من حيث الانّتشار في الترب المدروسة، ولكن الفلدسبار البوتاسي (الأورثوكلاز) كانت نسبته أقل من الكالسيت والكوارتز في الترب المدروسة، بينما وجد معدن البيروكسين فقط في ترب القطاعين الرابع والخامس حيث الصخرة الأم بازلتيّة، بينما وجد معدن الباليغورسكيت وبنسبة قليلة في جميع أنّواع الترب المدروسة ؛ أما معادن الطين الثانّويّة فقد وجد معدن السمكتيت بنسبة عاليّة في القطاع الثاني وبنسبة أقلّ في الأفق الأول لباقي القطاعات. كما وجد الميكا (وغالباً الإلّيت) والكاؤولينت والكلوريت بنسب أقل من السمكتيت في جميع عيّنات الترب المدروسة. وبينت نتائج الدراسة ﺍﻟﻔﻴﺯﻴﺎﺌﻴّﺔ ﺃنّ أغلب ﺍﻟﺘﺭﺏ ﺫﺍﺕ قوام ﻁﻴنيّ، وﺒﻠﻐﺕ ﺃﺨﻔﺽ ﻨﺴﺒﺔ ﻟﻠﻁﻴﻥ والهيغروسكوبية ﻓﻲ ﺍﻟﻌﻤﻕ ﺍﻟﺴﻁﺤﻲ ﻟﺘﺭﺒﺔ القامشلي (تل معروف) (41.00) و(5.06)% على التوالي، ﻓﻲ ﺤـﻴﻥ ﺸـﻜﻠﺕ ﺃﻋﻠـﻰ ﻨﺴﺒﺔ للطين والهيغروسكوبية (58.00) و(6.26)% على التوالي ﻓﻲ ﺍﻟﻌﻤﻕ الثالث ﻟﺘﺭﺒﺔ المالكية (دير دجلة)، وقيم الكثافة الظاهرية بين (1.19–1.33)غ/سم3، وتراوحت قيم الكثافة الحقيقة (2.62–2.75) غ/سم3، ورافقها تباين في قيم المسامية الكلية، إذ تراوحت قيمتها بين (50.15–54.58)%. ﺒﻴﻨﺕ ﺍﻟﻨﺘﺎﺌﺞ الكيميائية والخصوبيّة ﺃﻥّ ﺩﺭﺠﺔ (pH) التربة معتدلة في الأفق السطحي لتربة القامشلي، إذ بلغت (7.71)، وتصبح متوسطة القلويّة أكثر من (8.00) بقليل، ومحتوى التربة للكاتيونات المتبادلة من متوسط إلى عالٍ، ﺇﺫ ﺘﺭﺍﻭﺤـﺕ ﺒـﻴﻥ (32.24 و45.32) ﻤﻠﻴﻤﻜﺎفئ/100غ ﺘﺭﺒﺔ، ويشغل كاتيون الكلسيوم ﺍﻟﻤﺭﺘﺒﺔ ﺍﻷﻭﻟﻰ ﻋﻠﻰ ﻤﻌﻘﺩ الامتصاص يأتي بعده ﺍﻟﻤﻐﻨيسيوﻡ. يعتبر محتوى الترب المدروسة من المادة العضويّة في العمق الأوّل منحفضة لأنّ قيمتها تترواح بين قيمتي (00.5 –01.0) %،. ﻭتراوحت ﻨﺴﺒﺔ كربونات الكلسيوم ﺍﻟﻜﻠّﻴﺔ ﺒﻴن أدنى قيمة (21.63%) في تربة المالكية (دير دجلة)، وأعلى قيمة (31.91%) في تربة القامشلي (تل معوف). وبدراسة حركية البوتاسيوم تبين أن قيم ARKe تراوحت بين (0.092 و 0.183) (مول/ليتر)2/1 حيث سجلت أعلى قيمة للفعالية الأيونية في تربة المالكية 0.0183)) (مول/ليتر)2/1 وأقل قيمة للفعالية الأيونية في تربة القامشلي (0.0092) (مول/ليتر)2/1 . وإن قيم K∆ للترب المدروسة تراوحت من ((0.3595 – 0.885) سنتي مول.كغم-1، حيث تراوحت قيم السعة التنظيمية لجهد البوتاسيوم للترب المدروسة بين (33.751- 60.314) [cmol kg-1]/(M L-1)0. 5]. بأن قيم معامل كابون تراوحت بين (0.867 – 1.713) ليتر.مول-1.

SLAKES and 3D Scans characterize management effects on soil structure in farm fields

Adoption of no-till (NT) is low in the Lower and Middle Brazos River Watershed of Texas, leaving soil vulnerable to erosion, exacerbating flooding, and contributing to high nutrient and sediment levels in surface waters. To investigate the impact of NT on soil structure and hydraulic function in the region, we measured saturated hydraulic conductivity, organic carbon, bulk density, slaking index of soil aggregates (inversely related to aggregate stability), and soil structure in farm fields under three management systems: conventional tillage (CT), NT, and perennial grass (PG). Soil structure was measured using a novel method for 3D scanning of soil surface horizons – multistripe laser triangulation. Slaking index was measured using a recently developed smartphone application. Exploratory factor analysis combined with a semi-supervised cluster analysis showed that, in general, CT and PG fields were classified into different clusters from one another. Three fields managed with NT for 21, 21, and 7 years were classified in the same cluster as PG fields, while the remaining fields (managed with NT for 21, 21, 18, and 3 years) were classified with CT fields. Organic carbon was significantly higher in NT compared to CT fields. Conventional fields had significantly lower hydraulic conductivity than PG fields and hydraulic conductivity was 1.3 cm h−1 higher in NT than CT fields. Soil structure measured from 10–30 cm depth was significantly improved in NT compared to CT. Improvements in organic carbon and soil hydraulic function are meaningful indicators of improved physical soil health that can be used to promote NT adoption. Improvements in organic carbon and soil hydraulic function also provide ecosystem services to off-site stakeholders who are impacted by erosion and sedimentation resulting from soil tillage. The two novel measurements (a metric derived from scanning of soil structure and slaking index from a smartphone application) were particularly sensitive to management system.

The Effect of Organic and Conventional Farming Systems with Different Tillage on Soil Properties and Enzymatic Activity

The chemical properties and enzymatic activity of the surface soil horizon were compared between an organic farm (OF) (crop rotation with legume plants, fertilisation with manure) and a conventional farm (CF) (simplified crop rotation, mineral fertilisation, chemical crop protection products). In the years 2001-2017 on the OF (near the village of Juchowo, northern Poland), a reduced tillage system (ploughless) was used, while plough cultivation was used on a CF located in its immediate vicinity. The parameters used to assess the properties of soils were: particle size composition, pH, total organic carbon (TOC) and total nitrogen (TN), dissolved organic carbon (DOC) and dissolved organic nitrogen (DON). The activity of dehydrogenases (DEH), catalase (CAT), alkaline phosphatase (AlP) and acid phosphatase (AcP) and the content of easily extractable glomalin-related soil protein (EEGRSP) were also determined. Sixteen years of soil use in accordance with ecological principles significantly increased the average content of TOC, NT, DOC and DON. Soil samples rich in TOC and DOC showed significantly higher DEH and AcP activity, and EEGRSP content. Statistical analysis showed that the activity of DEH, AlP and CAT in the soil was significantly higher for the OF than for the conventional cultivation system. Limiting soil cultivation procedures on the OF improved the balance of soil organic matter (SOM) and pH value, and significantly increased the content of EEGRSP as compared to the cultivation system used on the CF.