Soil-forming Processes Research Articles

The Influence of Sewage Sludge Composts on the Enzymatic Activity of Reclaimed Post-Mining Soil

Mining leads to serious degradation of the ecological values of the landscape. After mining is completed, degraded areas should be reclamated in order to mitigate the destructive effects of mining activities. Effective reclamation aims to initiate soil-forming processes. The paper evaluates the effects of land reclamation in post-mining areas 12 to 14 years after the reclamation process. The assessment was based on a determination of the activity of selected enzymes. Municipal sewage sludge compost (SSC) and compost with a composition of 70% municipal sewage sludge + 30% fly ash (SSFAC) were used as an external source of organic matter in the reclamation. The activity of dehydrogenases, phosphatases, and urease was determined. The fertilization of reclaimed soil with compost caused a significant increase in the activity of the assessed enzymes. Significantly higher dehydrogenase activity was found in the soil treated with SSC. The soil treated with SSFAC was characterized by higher activity of phosphatase and urease. The one-time application of composts from sewage sludge and sludge with fly ash, and the introduction of a mixture of grasses, allow for a permanent reclamation effect. An additional ecological advantage of this reclamation model is waste management, which is part of the circular economy strategy.

Vertical changes in P-acquiring enzyme activities and microbial biomass in Luvisols – The effect of different types of agricultural land use and soil-forming processes

The activities of enzymes involved in the transformation of soil organic P are rarely measured in soils below a 30 cm depth, even though substantial amounts of P are also stored in deep soils. Changes in soil microbial biomass and the activities of P-cycling enzymes with depth were determined across the eight Luvisol profiles in four agricultural land uses including lucerne, winter wheat, vineyards and orchards. The activities of acid phosphatase (AcP), alkaline phosphatase (AlP) and phosphodiesterase (PDE) were assessed, as was the microbial biomass carbon (MBC) and phosphorus content (MBP) as well as some physico-chemical properties (e.g. total organic carbon – TOC, total nitrogen – TN, available phosphorus – Pavail, bulk density, pH in CaCl2). Additionally, mass and morphological parameters of the plant roots were also determined. The highest enzymatic activity and microbial biomass C and P content were found in the surface and sub-surface horizons and decreased with depth to varying degrees in parallel to the changes in TOC and TN. The studied properties were primarily determined by means of the organic C content and availability in all genetic horizons, while the influence of the lessivage (clay content) was only clearly pronounced for AcP activity, which was significantly higher in the illuvial layers (E) as compared to the eluvial horizons (Bt) in most of the considered profiles. What is more, only AcP activity was significantly and positively related to the root biomass and the number of small roots in the plants. Although it was revealed that the particular plants being cultivated had a significant impact on AcP activity, the data should be interpreted with caution because other factors (e.g. mineral fertilization) may also contribute to this.

Vulnerability of diked marsh ecosystems under climate change

Diked marsh soils are natural laboratories where soil-forming processes take place over a short period of time, such as the aeration of previously water-saturated soil environments along with desalinization. These manmade ecosystems are threatened by climate change in multiple ways. Since long-term data to evaluate the vulnerability of these settings is scarce, we merged hydrological (water table, WT; electrical conductivity, EC; sea level rise), pedological (redox potential, EH; air-filled porosity, AFP), and meteorological variables (evapotranspiration, ET0; climatic water balance, CWB), and discussed the holistic relationship between these under future climate scenarios. Our multifactorial data identified ET0 as the strongest driver of WT development with a causal dependency on AFP and subsequently on EH. Within 11 years of intense monitoring, we encountered an extension of the soils’ aeration windows (EH > 300 mV) due to an enhanced seasonal WT component; i.e., the difference between winter and summer WT positions increased. This process has an impact on capillary rise from groundwaters and EC patterns due to increased seasonal variations. Desalinization stabilized two decades after diking, and the present EC does not indicate any saltwater intrusion to these near-coastal settings at present. However, sea level rise and a reduced CWB in the future will foster capillary rise from potentially salt-enriched groundwaters into the topsoils of these highly productive ecosystems. These mechanisms need to be evaluated to account for climate change–driven impacts on coastal-diked marsh soils. Indeed, a holistic view of pedological, meteorological, and hydrological variables is urgently needed.

The influence of burial rate on variability in tephra thickness and grain size distribution in Iceland

We explore whether the rate at which a tephra deposit is buried influences the variability (thickness and grain size distribution) within the tephra layer subsequently preserved within the stratigraphic record. This has important implications for understanding how processes of soil formation interact with the creation of a volcanic record. To assess the relationship between soil formation and the preservation of tephra layers, the thickness and grain size distribution of the Katla 1918 tephra in Iceland and the rate at which it was buried (inferred from the thickness of the overlying soil) was measured 1620 times at six locations. Tephra layer thickness does not correlate with rate of burial, but the proportion of original deposit retained does, and variations in grain size distribution are correlated with burial rate. Our results indicate that whilst medium term (i.e. years-decades) burial processes may contribute less to tephra layer variability than environmental processes operating immediately after deposition, rapid burial facilitates better preservation of the original fallout characteristics with important implications for the accurate reconstruction of past volcanic eruptions based on tephra layer characteristics. There are two key implications: firstly, sites need to be chosen where surface characteristics minimise the initial alterations of tephra deposits, and secondly sites with rapid burial will produce the best quality data, although workable data can be gathered elsewhere if areas of uncertainty are acknowledged.

Chemical Composition of Tissues of Syringa vulgaris L. and Soil Features in Abandoned Cemeteries

Abandoned anthropogenic sites are transformed when they come into use. In the present study, such objects were abandoned Evangelical cemeteries located in the Land of the Great Mazurian Lakes (northern Poland). This study aims to compare the concentrations of selected major (Ca, Na, Mg, Al, Fe) and potentially toxic elements (Zn, Cd, Pb) in the roots, leaves, and branches of Syringa vulgaris and buried necrosols and unburied soils in which this species grows. The soils analysed differ in their profile structure; in the case of burial necrosols, anthropogenic layers are present, while Brunic Arenosol has a natural horizon arrangement. Regarding pH, the soils analysed are characterised in the weakly acidic (6.6–6.8) to alkaline (7.2–8.6) range, both in KCl and H2O. Total phosphorus has high values in the humus and anthropogenic horizons, especially at coffin sites (Rudówka Mała: layer of Ccoffin—759 mg∙kg−1; Szymonka—844 mg∙kg−1). Necrosols are characterised by a slightly higher variation in major element content than soils outside the burial area. The highest elemental content in Syringa vulgaris is accumulated in leaves and roots. Potassium (K) has the highest content in the studied tissues, and cadmium (Cd) is the lowest. The study showed no significant differences in heavy metal accumulation for plants directly associated with necrosols and soils formed outside of burials, which is confirmed by analyses of environmental indicators. The study showed that plant chemistry is more influenced by the soil substrate and soil-forming process than the soil anthropogenisation associated with burials. There was no significant effect of burials on the chemical composition of individual parts of Syringa vulgaris.

Main influencing factors of soil particle distribution in the karst basin

Soil particle distribution is an important soil property that is widely studied. However, more attention has been focused on specific environmental factors. As soil and environmental factors of nature are related, what is the relationship between soil particle distribution and environmental factors? What are the most important factors affecting soil particle distribution at the watershed scale? The principal component dimension reduction analysis showed that the important factors affecting soil particle distribution included and ranked as parent material, slope and slope position. The karst soil in the Houzhaihe Basin, Guizhou Province, China, is taken as the research object. A grid of 150 m·150 m is used for sampling, and the total number of sample collection points is 2755. The effects of seven environmental factors (soil parent material, land use type, slope direction, slope, soil type, slope position and altitude) on soil particle distribution were studied. The results showed that the seven factors all significantly affected the soil particle distribution in the basin, but the significance of different factors was distinct, and some factors had no significant effect on the specific particle type. The principal component dimension reduction analysis showed that the important factors included parent material, slope and slope position, which were ranked as parent material, slope and slope position. On the one hand, the change in soil particle distribution is affected by the factors of the soil formation process (parent material) and by the transport and transportation of dynamic factors such as water and gravity (slope and slope position) in the basin. The change in soil particle distribution is driven by the coupling of these two factors. The redundancy analysis shows that the contribution rates of environmental factors to the content of three kinds of soil particle sizes are arranged in the order of soil parent material, land use type, slope direction, slope, soil type, slope position and altitude and explained 14.2 %, 8.9 %, 3.4 %, 3.0 %, 1.9 %, 1.5 % and 0.9 %, respectively, and only three of them reach the level of P < 0.05. The results of high-density sampling analysis at the karst basin scale show that the parent material is the most important factor affecting the soil particle distribution.

RETRACTED: A tropical soil (Ferralsol) identified in the northernmost part of the Mediterranean (Istria, Croatia)

Terra rossa soils on the Istrian peninsula are generally considered polygenetic relict soils. They overlie and mark the youngest subaerial unconformity in the northwestern part of the Adriatic Carbonate Platform and are susceptible to erosional and redepositional processes. Terra rossa soils represent a valuable archive of information that can be used to understand present and past soil formation processes in the context of climate variability and landscape dynamics, especially in low-lying parts of the karst landscape where thicker deposits are typically found. We studied a 3 m thick terra rossa profile in a karst depression on the northernmost part of the southwestern Istrian planation surface and analysed the micromorphology, physical/chemical properties, geochemistry, bulk and clay mineralogy, and composition of heavy and light mineral fractions. The profile shows several signs of colluviation and polygenesis with clay distribution along the profile, clearly indicating lithic discontinuities. Kaolinization, along with iron oxide formation, is the dominant process in the studied profile. Ferralitization and lessivage processes were diagnosed throughout the profile, with intense clay translocation occurring despite the extremely stable soil microaggregates. In accordance with the WRB system, the profile is classified as Lixic Rhodic Ferralsol (Clayic, Aric). This implies that some terra rossa soils, previously classified as e.g. Cambisols or Luvisols, might actually be Ferralsols or other tropical soils (e.g. Lixisols), in which relict properties are preserved in the present climate. The finding of a Ferralsol in the study area indicates the old age of the surface of the karst depression and provides the first data on the burial history of the southwestern Istrian planation surface. We suggest the older Quaternary interglacials, the mid-Piacenzian Warm Period (Pliocene) and the Miocene Climatic Optimum as favourable periods for the formation of the studied soil.

Qualitative composition of humus and physical and chemical properties of typical chernozem depending on the fertiliser system

The soil-forming process is closely related to the accumulation and circulation of organic substances, which are a source of nutrients for plants released during the mineralisation of humus, so research on determining the qualitative composition of humus is relevant. In this regard, the purpose of this paper is to determine humic and fulvic acids in typical chernozem, depending on the fertiliser system. The leading approaches to solving this problem are conducting field and laboratory studies to determine the quality indicators of humus and dispersion methods to establish the accuracy and reliability of experimental data. Based on the conducted studies, it was observed that the application of an organo-mineral fertiliser system leads to an increase in the content of humic acids, while the insoluble residue shows an increase in carbon content. The utilisation of organo-mineral fertilisers resulted in a reduction in the excessive accumulation of non-humified organic substances. Additionally, the soils in these areas exhibited a higher level of organic substance humification. The combination of organic matter at a rate of 11.5 tonnes per hectare (8 tonnes of manure and 3.5 tonnes of by-products) and mineral fertilizer N27P38K45 in a crop rotation resulted in an increasing trend of the buffering capacity of typical chernozem soil. In this scenario, there was an increase in absorption capacity at the end of the second rotation for grain-legume crop rotation by 6.05 mg/equiv per 100 g, specialised grain-legume rotation by 3.9 mg/equiv per 100 g, and legume rotation by 3.06 mg/equiv per 100 g of soil compared to the beginning of the first rotation. The use of organo-mineral fertilisers increases the third fraction of fulvic acids in specialised grain-legume rotation, which affects the ratio of humic acids to fulvic acids in favour of the humic type of humus formation. The ratio of humic acids to fulvic acids in the grain-planting crop rotation in the organo-mineral system was 2.84 at the end of the second rotation, and 2.24 at the beginning of the first rotation. The research materials are of practical importance for farmers when analysing the fractional-group composition of typical chernozem humus

Source apportionment of heavy metals in the soil at the regional scale based on soil-forming processes

Source apportionment is crucial to the prevention and control of heavy metals in the soil. The major methods focus on the identification of soil heavy metals from different pollution sources. However, they are unsuited to the source apportionment at a regional scale due to ignoring the spatial heterogeneity of heavy metal content caused by soil formation. Thus, we built a source apportionment model by introducing the weathering and leaching coefficients as the key parameters of soil-forming processes. In this study, we selected Liaohe Plain in China as the study area, which was the starting point of China's industrial development, with dense industrial areas and high levels of heavy-metal emission. Heavy metals concentrations in surface and deep soil of reference and grid points were collected as model data. The results showed that the average contribution rates of soil-forming process to Cd, Hg, As, and Pb were 82.7%, 85.2%, 88.6%, and 91.7%, respectively, and those of anthropogenic activities were 17.3%, 14.8%, 11.4%, and 8.3%, respectively. Spatial distribution of contribution rates showed the superposition of soil environmental background and pollution sources. This study provides a feasible method to quantify heavy metals contents from natural and anthropogenic sources at a regional scale.

DEPARTMENTS OF GEOGRAPHY OF UKRAINE, SOIL SCIENCE AND LAND CADASTRE OF ODESSA UNIVERSITY – 55TH ANNIVERSARY!

In the structure of Odesa I. I. Mechnikov National University University in 1967, the Department of Soil Science and Geography of Soils was established (since 2017 – the Department of Geography of Ukraine, Soil Science and Land Cadastre), the main tasks of which is the study of modern soil-forming processes in chernozems of the steppe zone, mainly under conditions of irrigation and drainage, and soil mapping and lands in order to rationalize their use. In connection with the 55th anniversary of the operation of the Department at the University, the proposed publication highlights the history of the establishment and development of the Department, the main directions and achievements of educational and research activities.

Органическое вещество гранулометрических фракций и его роль в формировании морфогенетического своеобразия буроземов острова Русский

The features of the fixation of humus substances by particle-size fractions of soil for the main types of burozems of the Russky Island are characterized. It is shown that the diagnostic indicator of the morphological diversity of island burozems soils, reflecting the different intensity of the development of accumulative-humus and illuvial-humus processes of soil formation in their profile, is the level of carbon accumulation in the fractions of silt and fine dust, the share of carbon of these fractions in the structure of the total humus and the features of its profile dynamics. It has been established that in typical burozem, the bulk of carbon is confined to the fraction of silt, with depth the role of silt in fixing the organic matter of these soils only increases. In dark burozem, the carbon content of the silty fraction increases almost twice as compared to typical brown soils, and its share in the composition of total soil carbon decreases. At the same time, the saturation of the organic matter of the upper humus horizon with carbon of the fine dust fraction increases. The most significant changes in the structure of total carbon and in the level of its accumulation by particle-size fractions are noted for dark illuvial-humus burozem. An important diagnostic feature of dark illuvial-humus burozem is that the fine-dusty fraction participates in the accumulation of organic matter more than the silty fraction, both in the upper humus horizon and in the sub-humus horizon. In the lower part of the profile of all burozems, the concentration of humus in the silt increases almost twice, accounting for more than half of its gross content in the soil.

Geochemistry Process from Weathering Rocks to Soils: Perspective of an Ecological Geology Survey in China

Ecological characteristics are very important for the Earth’s environment and human lives. Recently, more attention has been paid to the ecological problems in the world. The soil and its parent materials/rocks serve as the supporting materials for the ecological system on the Earth’s surface. The ecological characteristics in one region are associated with or even dependent on the soil-forming process. Thus, the study of the weathering process of parent materials/rocks is important for our understanding of the geological genesis of ecological problems. In this study, three typical ecological problems in China are introduced: land salinization in the north, the desertification of land in the northwest, and Karst rocky desertification in the south. We chose 23 typical profiles for observation and sampling. The soil-forming processes in these areas were investigated by geochemical research, and eco-geology models were subsequently established to explain the profound relationship between vegetation cover and the soil-forming process. Our work first focuses on the geochemical methods used to explore these ecological issues, emphasizing the contribution of the geological genesis to the ecological characteristics. Using geochemical methods, such as the chemical index of alteration (CIA), major element and trace element distribution characteristics, the formation processes, and characteristics of bedrock-weathering soils under diverse epigenetic geological settings were determined. Eco-geology models were then developed by evaluating the vertical structure and material composition of soil, the characteristics of elemental migration during soil formation, and the enrichment and loss of elements in the supporting layers and their repercussions.

Investigation of Relationships Between Available Boron and Soil Properties

Soil formation processes and cropping and management practices affect plant-available amounts of boron (B) in soils. Using Pearson's correlation and principal component analyses, this study investigated the relationships between soil properties and plant-available boron concentrations in 69 soil samples. In principal component analysis (PCA), 73.079% of the variance was explained with four components. Plant-available B in the soil was significantly correlated with phosphorus, potassium, pH, and electrical conductivity (EC), showing that phosphorus and potassium fertilizer producers would be adding boron to fertilizers, although it is not mentioned on their packages. Also, the tide correlation between B and either soil pH and EC was attributed to greater solubility B, pH and EC. The majority of the experimental soils were deficient in boron. Therefore, boron fertilizer must be added to the fertilization program to mitigate the losses caused by boron deficiency in low-input agricultural production fields.

Microdispids mites of Turkmenistan and their ecological groups

This study presents the results of research on the ecology of microdispids mites in Turkmenistan. In particular, 8 species of microdispids mites were found in the soil and anthills. The importance of these mites in the decomposition of plant residues and in soil-forming processes is shown. Data on seasonal changes in the abundance and vertical distribution of microdispids mites in irrigated soils are presented. The phoretic relationship of microdispids mites with ants has been proven. Mushrooms adapted to grow in anthills serve as food for microdispids mites. The importance of anthills is indicated as a special place for shelter and a center of mass reproduction of mites, therefore, as a specific biotope in arid conditions.

Роль мелиорации в повышении продуктивности сельскохозяйственных земель на примере Московской области

When making decisions about putting unused agricultural lands into turnover, it is advisable to estimate their potential productivity under the current climatic conditions. The analysis of energy expenditures of the main components of the natural process of soil formation (radiation balance, PAR, moistening coefficient) for Moscow region of CFD by weather stations of Dmitrov, Kolomna, Staritsa was carried out. The mechanism of influence of ameliorative measures on the components of radiation balance is described and the dependencies allowing for calculation of energy accumulated in the annual growth of vegetation mass and energy consumption for soil-forming process corresponding to the calculated energy amount are given. The calculations of theoretically possible crop yields at introduction into agricultural production of unused lands with different values of PAR during the vegetation period are presented. The assessment of climatically secured crop capacity of three researched plots was carried out by the example of 2021 and comparison with actually obtained capacity in the farms, where the researched plots are located, which are planned to be put into agricultural turnover. The purpose of the study is to assess the role of reclamation in increasing the productivity of unused lands when making decisions on their return to agricultural circulation based on the results of an assessment of their current state using the example of the Moscow Region.

О генетической (гносеологической) теории мелиорации сельскохозяйственных земель

Based on studying the regularity of the formation of the genetic theory of runoff by A.I. Voyeykov, which belongs to the dependence of river runoff, atmospheric precipitation, and total evaporation, an attempt was made to establish a causal relationship between the coeffi cient of natural moisture by N.N. Ivanov, the «dryness index» or hydrothermal indicator by M.I. Budyko, and the energy costs of soil formation by V.R. Volobuev, in order to form a genetic (gnoseological) theory of agricultural land improvement. Using philosophical ideas and worldview in the fi eld of natural resource management, a logical framework for the genetic theory of agricultural land improvement was constructed, and based on them, a calculation method was proposed to determine the ecological norm of water consumption for agricultural lands for purposeful management and regulation of the soil formation process and productivity of reclaimed lands.

The possibility of physico-theoretical methods in soil ecology (the case of modeling soil-climatic areas structure)

The aim of the study was to consider the possibilities of up-to-date physical and theoretical methods for solving problems of soil ecology related to the mathematical description of the regularities of the systemic organization of soil-climatic areas according to hydrothermal factors of the environment. Methods. Methodological analysis of the idealizations, hypotheses and concepts was used alongside with mathematical modeling. Results. Methodological analysis of the assumptions underlying the quantitative determination of the two traditional hydrothermal coefficients (the radiation index of dryness, R/LP, and the moisture coefficient, P/E0) justifies their attribution to the marginal (boundary) soil conditions, determined mainly by climatic characteristics. From the physico-theoretical (quantitative) point of view, this is one of the reasons for their limited applicability when considering soil and ecological problems related to the quantitative description of the relationship between the types of soil thermal and water regimes and the general climatic patterns of their distribution on the earth's surface. Based on the fundamental principle of affine similarity (a variety of the general principle of symmetry), the article suggests the new generalized variables R/Eα and P/Eβ. In these variables soil moisture evaporation E(R,P), determined for the entire range of the average long-term climatic characteristics of R (radiation balance) and P (precipitation), acts as a general reference system. The specificity of the hydrothermal response of the soil substrate is determined by the corresponding structural and functional indices of similarity α and β. The physical meaning of the new variables is that they characterize the totality of radiation energy (α) and precipitation (β) use by specific soil-forming process. Conclusions. A mathematical model, based on the functional association between the generalized variables, enables predicting new structural and functional regularities (radial and tangential) in the system of soil-climatic areas. In comparison with the climatic hydro- and thermoseries proposed by V. R. Volobuev, these regularities better describe the experimental data.

Agroecological assessment of agricultural soils fertility in the Iglinsky region, the Russian Federation

The article provides an assessment of soil fertility indicators of agricultural lands in the northern foreststeppe of the Republic of Bashkortostan within the Iglinsky region (Russian Federation). The content of humus, mobile phosphorus, exchangeable potassium, the thickness of the humus horizon, granulometric composition, morphological properties and soil washout were studied. It was revealed that the soil-forming process occurs on rocks of different ages and genesis, such as diluvial carbonate and carbonate-free clays and heavy loams, limestone eluvium, sandstone eluvium and alluvial deposits, which determine the diversity of the soil cover. In the study area, water erosion processes are developing, influenced by anthropogenic and natural factors such as planar and linear washout on slopes with a steepness of more than 2–3° and high ploughing of agricultural land. In terms of humus content, low-humus and medium-humus soils are widespread, accounting for 45.5 and 40%, respectively. The soil map was corrected and digitised to identify the main types and subtypes of soils, indicating the varieties at a scale of 1: 25,000. Digitised maps, taking into account the current state of soil fertility, are used to develop projects for inter-farm and intra-farm land management of organisations of the agro-industrial complex, state cadastral valuation of agricultural land, determination of land tax and development of measures to improve soil fertility.

GEO-TOURIST SITES AND ROUTES IN THE TERRITORY OF SAMBIR-KHYRIV TERRACE FOOTHILLS

The geological and geomorphological objects of Sambir-Khyriv terrace foothills have been characterized as natural monuments and potentially popular geo-touristic sites. The foothills cover the pre-Carpathian sections of the Stryvihor and Dniester valleys, the entire Bolozivka valley and the uplands of the interfluves. The main geomorphological elements of the study area are river valleys with a complex of river terraces of different ages. Outside the valleys, in the uplands of the interfluves, the most ancient foothill terraces and different-aged denudation leveling surfaces are spread. Relief-forming deposits of the foothills are mainly represented by Neogene and Anthropogenic accumulations. The anthropogenic depositsoverlapping the older accumulations are extremely heterogeneous in terms of genesis, age, and lithological structure. Within the foothills, the most valuable natural monuments are the following objects: sections of anthropogenic accumulations Slokhyni, Torhanovychi 1 and 2 and Kruzhyky, as well as landforms, i.e. a fragment of Krasna surfacedeveloped on the eastern macro-slope of RadychMountain and the western part of the Bolozivka valley. We identify the listed objects as stratigraphic and geochronological (sections of Slokhyni, Torhanovychi 1 and 2 and Kruzhyky), paleontological (section of Kruzhyky), geomorphological (surface of Krasna, Bolozivka valley),and scenic natural monuments (surface of Krasna). Foothill natural monuments are important in terms of research and geo-educational functions, in particular to study and illustrate stratification of sedimentary accumulations of anthropogenic age; lithological and sedimentological features of continental deposits; variability of paleogeographic conditions of anthropogenic age; cyclicityof continental morpholithogenetic processes; formation of exogenic forms of relief due to denudation shearing of uneven surface of the Earth, erosion and accretion activity of fluvial flows; soil-forming processes; and geological age of human material culture. The described natural monuments are important for the organization of events intended to popularize geological and geographical science, as well as environmental education among people, and teach the skills of careful attitude to the environment. It would befeasible to integrate them into the existing network of tourist routes inLviv region. Key words: Sambir-Khyriv terrace foothills; natural monuments; sections of anthropogenic deposits; surface of Krasna; Bolozivka valley.

Interactive effect of parent material and topography on spatial variability of paddy soil material characteristics in the alluvial plain

ABSTRACT To investigate the interactive effects of parent material and topography as soil forming factors, we examined the distribution of soil materials in an alluvial plain, where two types of surface geology were situated upstream and different parent materials supplied accordingly. We hypothesized that these two types of parent material make it possible to trace alluvial processes by analyzing their spatial distribution based on soil physicochemical properties. We collected 101 soil samples from the alluvial plain and nine soil samples from two types of unmixed upstream areas, i.e., granite and mélange. Particle size distributions and total concentrations of 32 elements were analyzed for spatial variabilities. Elemental composition of unmixed upstream samples and isarithmic maps of elemental composition of the soils in the alluvial plain based on geostatistical analysis revealed that gravel, coarse sand and total Na, Al, K, Ca, and Mn concentrations were higher at the southern part close to granite rock areas, whereas silt+clay content and total C, N, Mg, Ti, and Fe concentrations were higher at the northern part close to the mélange area, suggesting strong influence from parent material. In contrast, fine sand content and total P and Si concentrations showed west-east trends, suggesting topography effects reflecting particle size selection. Directional semivariograms suggest coarse sand and silt+clay content, as well as total C, N, Na, Mg, Al, K, Ca, Ti, and Mn concentrations were more strongly affected by parent material, whereas gravel and fine sand and total P concentration were more strongly affected by topography. Accordingly, the combination of elemental composition analysis and geostatistics revealed that the contribution of parent material and topography to total elemental contents in paddy surface soils in the alluvial plain varied among elements. In conclusion, evaluation of the interactive effects of parent material and topography on spatial variability of soil material characteristics enabled better understanding of soil formation processes and their potential fertility.