The vegetation cover dynamics (1982–2006) in different erosion regions of the Yellow River Basin,China

Vegetation significantly influences human health in the Yellow River basin and the plant cover is vulnerable to people. Typical types of erosion in the Yellow River basin include that caused by water, wind and freeze–thaw. In this paper, vegetation cover change from 1982 to 2006 was studied for a number of different erosion regions. The Global Inventory Monitoring and Modeling Studies Normalized Difference Vegetation Index (GIMMS NDVI) data were employed, while climatic data were also used for analysis of other influencing factors. It was shown that: (1) generally the vegetation cover in different erosion regions displayed similar increasing trends; (2) spatially the vegetation cover was highest in the water erosion region, the second highest was in the freeze–thaw region and the lowest in the wind erosion region; and (3) vegetation cover in the Yellow River basin is influenced by climate factors, especially by temperature. In water erosion regions, the temporal change of vegetation cover seemed complicated by comprehensive climatic and human influences. In wind erosion regions, the vegetation cover had close relations to precipitation. In freeze–thaw erosion regions, the vegetation cover was primarily altered by temperature. In all the three erosion regions, significant change of the vegetation cover occurred from 2000 just after the ‘Grain for Green’ (GFG) programme was implemented throughout China. Copyright © 2010 John Wiley & Sons, Ltd.     

Effect of rock fragment cover on interrill soil erosion from bare soils in Western Andalusia, Spain

It is known that rock fragments on the surface of soils can enhance infiltration and protect the soil against rainfall erosion. However, the effect of rock fragments in natural forest soils is less well understood. In this article, we studied the influence of rock fragment cover on run‐off, infiltration and interrill soil erosion under simulated rainfall on natural bare soils in a Spanish dehesa (managed holm oak woodland). We studied 60 plots with different rock fragment cover ranging from 3% to 85% under three simulated rainfall intensities (50, 100 and 150 mm/h). Surface run‐off appeared later and sediment yield values were smaller in soils with greater rock fragment cover. Rock fragment cover also increased infiltration rates. The final infiltration rates were 54–98% at a rainfall intensity of 50 mm/h, 31–88% at 100 mm/h and 20–80% at 150 mm/h. The interrill soil loss rates were decreased by rock fragment cover and increased with rainfall intensity. The soil loss rate was always small (0.02–1 Mg ha/h) when rock fragment cover was 75% or more. Rock fragment cover was related to soil loss rate by an exponential function.     

Effect of sowing methods and sowing rate in organic seed production of timothy (Phleum pratense L.), meadow fescue (Festuca pratensis Huds.) and red clover (Trifolium pratense L.)

Different sowing methods and sowing rates were evaluated in organic seed production of timothy (two trials), meadow fescue (two trials) and red clover (one trial) in Southeast Norway, during 2010–2013. The plan included: (1) broadcast sowing of grass/clover, cover crop sown at 12 cm row distance; (2) sowing of cover and seed crop in crossed rows, both at 12 cm row distance; and (3) sowing of cover crop and seed crop in every other row. The three sowing rates were 5, 10 and 15 kg ha–1 in timothy and meadow fescue and 3, 6 and 9 kg ha–1 in red clover. On average for sowing rates and all trials with timothy, meadow fescue and red clover, first year’s seed yields were 5–6%, 20–25% and 19–25% higher on plots sown with cover crop and seed crop in every other row than on plots where seed crop had been broadcast or sown perpendicularly to the cover crop. The different sowing methods had no effect on weed coverage or weed contamination in the cleaned seed. Increasing sowing rate usually had a negative influence on seed yield, while weed coverage/contamination was not significantly affected. It is concluded that organic seed crops should be established with cover crop and seed crop in every other row at a low sowing rate. However, in an organic production system, even this favorable method will not always be sufficient to meet the requirement for seed crop purity.     

Effects of a plastic cover on soil moisture change in a Mediterranean climatic regime

Water deficit is a serious problem for most agricultural crops, especially in arid–semiarid regions, and limits sustainable development. Production can be improved by reducing evapotranspiration and loss of infiltrated water by the use of a plastic cover. We monitored soil moisture fortnightly over 1 yr using a neutron probe near four trees in an olive grove (Olea europaea, var. Arbequina), two of which had a plastic cover buried in the topsoil around them. These trees were monitored using three neutron probe access tubes per tree to compare the behaviour of soil moisture over time with two other identically instrumented and nearby trees with no cover. Analysis was based on the resultant moisture profiles. The plastic cover retained moisture and increased soil water residence time. During the dry season, the amount of water retained in the plots was at most 15–20% greater in the mid‐season and at least 5–6% greater at the end of season than in the central part of the plots near the trunk. The plastic cover was effective to ca. 50 cm with maximum water content near the soil surface. During the wet season, the cover did not affect soil water. Soil moisture was greater near the tree trunk as a result of stemflow and throughfall.     

Soil microbiological properties and its stratification ratios for soil quality assessment under different cover crop management systems in a semiarid vineyard

In vineyards in Spain, tillage and semiarid Mediterranean climatic conditions accelerate organic matter loss from the soil. Cover crops are a conservation management practice that can provoke changes in soil quality which requires evaluation. Stratification ratios of soil properties such as soil organic C and labile C fractions have been proposed for the assessment of soil quality under different soil management systems. Our objective was to study the effect of different cover crop management on various soil parameters and their stratification ratios. We evaluated three different soil managements in a Typic Haploxerept from NE Spain: conventional tillage (CT); 5‐y continuous cover crop of resident vegetation (RV); and 4‐y continuous cover crop of Festuca longifolia Thuill., followed by 1‐y Bromus catharticus L. after resowing (BV). We monitored soil organic C, particulate organic C, water soluble C, potentially mineralizable N, microbial biomass C, β‐glucosidase and urease enzymatic activities, and water stable aggregates at 0–2.5, 2.5–5, 5–15, 15–25, and 25–45 cm soil depths. We calculated soil depth stratification ratios of those soil properties. Resident cover crop increased microbiological properties, labile C fractions, and aggregation with respect to conventional tillage at 0–2.5 and 2.5–5 cm soil depths. However, for Bromus cover crop the same soil properties were lower than for the resident cover crop at 0–2.5 cm depth. Stratification ratios of β‐glucosidase and urease enzymatic activities, and particulate organic C showed a higher sensitivity than other soil properties; therefore, they would be the best indicators for soil quality assessment in semiarid Mediterranean vineyards.     

Evolution of the soil cover of soccer fields

A soccer field can be considered a soil-like technogenic formation (STF). According to the theory of soil cover patterns, the artificially constructed (anthropogenic) soil cover of a soccer field is an analogue of a relatively homogeneous elementary soil area. However, the spatial homogeneity of the upper part (50–80 cm) of the STF of soccer fields is unstable and is subjected to gradual transformation under the impact of pedogenetic processes, agrotechnical loads, and mechanical loads during the games. This transformation is favored by the initial heterogeneity of the deep (buried) parts of the STF profile. The technogenic factors and elementary pedogenetic processes specify the dynamic functioning regime of the STF. In 50–75 years, the upper part of the STF is transformed into soil-like bodies with properties close to those in zonal soils. Certain micro- and nanopatterns of the soil cover are developed within the field creating its spatial heterogeneity.     

Hydraulic conductivity and porosity under conventional and no-tillage and the effect of three species of cover crop in northern France

We studied soil hydraulic conductivity (K) and porosity in five combinations of soil tillage and cover crop management systems. Treatments were winter wheat (Triticum aestivum L.) grown on a conventionally tilled soil (CT), on a no‐till soil (NT), and on an NT with three different cover crops: red fescue (Festuca rubra L.; Fr), bird's‐foot‐trefoil (Lotus corniculatus L.; Lc) and alfalfa (Medicago sativa L.; Ms). Measurements were made on a loamy soil in Grignon, France, in November 2004, May 2005 and October 2005. K and mean size of hydraulically active pores were measured in situ at three water potentials (?0.6, ?0.2 and ?0.05 kPa) at the soil surface and at 10 cm depth. In November 2004 and May 2005, pore space was described using 2D image analysis of pores on undisturbed soil samples in the 0–10 cm layer and in the 10–20 cm layer. The major differences were caused by soil tillage that created two heterogeneous soil layers and increased K in the 0–10 cm layer relative to NT. The effects of cover crop on K and porosity were not affected by the root type: there were no major differences between the grass cover crop (fibrous‐root type) and the leguminous ones (tap‐root type). However, we recorded larger functional pores and more tubules in the no‐till treatments with a cover crop, compared with the no‐till treatment without cover crop; this was probably the result of root activity. Although these changes generally did not result in larger values of K, they participated in the maintenance of soil structure and K over time.     

Cover crop potential of winter oilseed crops in the Northern U.S. Corn Belt

ABSTRACT

Winter camelina [WC, Camelina sativa (L.) Crantz] and field pennycress (FP, Thlaspi arvense L.) are emerging oilseed crops in corn–soybean rotations, but little is known about their cover crop potential. A 2-year study was conducted in Minnesota, USA to evaluate the effect of winter oilseed crops on nitrogen (N) use, growth and yield of corn and soybean. Treatments included WC, FP, winter rye (WR, Secale cereale L.), and a no cover crop (NC) control. Oilseed crops produced 40–50% less spring biomass and accumulated less N compared to WR. The tissue-N of WC and FP was 39.0% and 6.6% higher than WR, respectively. The C:N ratio of cover crops was lower than 20:1, suggesting rapid decomposition. Compared with NC, cover crops lowered soil nitrate before major crops planting, but the post-harvest N profile following corn and soybean was not affected. Compared with NC, cover crops significantly decreased corn yield, with 8.7%, 9.5% and 9.8% reduction following WC, FP and WR, respectively. Cover crops did not affect growth, yield and N uptake of soybean. Oilseed crops showed potential to improve N cycling in the rotation, but more research of their impact on major crops is needed.     

Hydrocarbons in the background soils of the southern- and middle-taiga subzones of the Komi Republic

The background content of hydrocarbons in soils of the southern and middle taiga has been assessed with consideration for the landscape and geochemical features of the area. Studies of hydrocarbons in soils of the taiga zone have showed that the position in the relief, particle-size distribution, and organic matter content are the main factors determining their content. The geochemical background of hydrocarbons is 50–100 mg/kg in the organic horizons of the soils on cover loams and 17–70 mg/kg in the soils on sandy deposits.     

Cover crops alter the soil nematode food web in banana agroecosystems

Cover crops are increasingly being used in agriculture, primarily for weed or erosion management. The addition of cover crops increases the primary productivity of the system and diversifies basal resources for higher trophic levels. How increases in the quality and quantity of basal resources affect bottom-up and top-down control remains a key question in soil food web ecology. We evaluated the response of the nematode community to the introduction of cover crops between rows of a banana plantation. We measured changes in nematode food web structure and inferred the prevalence of bottom-up and top-down effects on the abundance of phytophagous nematodes (i.e., plant-feeding and root-hair-feeding species) 1.5 years after plots with cover crops (Poaceae or Fabaceae species) or bare soil were established. The addition of a cover crop greatly affected the structure and the abundance of the soil nematode community 1.5 years after planting. The abundance of all trophic groups except for plant-feeding nematodes tended to increase with the addition of cover crops. The Shannon–Weaver diversity index and the enrichment index increased with the addition of cover crops, indicating that opportunistic, bacterivorous and fungivorous nematodes benefited from the added resources. Plant-feeding nematodes were least abundant in plots with Poaceae cover crops, while bacterivorous, omnivorous, and root-hair-feeding nematodes were more abundant with Fabaceae cover crops than with bare soil, indicating that cover crop identity or quality greatly affected soil food web structure. Bottom-up effects on all trophic groups other than plant-feeding nematodes were evident with Poaceae cover crops, suggesting an top-down control of plant-feeding nematodes by omnivorous nematodes. Conversely, plant-feeding nematodes were evidently not suppressed in Fabaceae cover crops, perhaps because bottom-up effects on omnivorous nematodes were weaker (hence, top-down control by omnivorous nematodes was weaker), and because Fabaceae cover crops probably served as good hosts for some plant-feeding nematodes.     

Characteristics of Nitrogen Loss through Surface-Subsurface Flow on Red Soil Slopes of Southeast China

Soil nitrogen (N) loss related to surface flow and subsurface flow (including interflow and groundwater flow) from slope lands is a global issue. A lysimetric experiment with three types of land cover (grass cover, GC; litter cover, LC; and bare land, BL) were carried out on a red soil slope land in southeast China. Total Nitrogen (TN) loss through surface flow, interflow and groundwater flow was observed under 28 natural precipitation events from 2015 to 2016. TN concentrations from subsurface flow on BL and LC plots were, on average, 2.7–8.2 and 1.5–4.4 times greater than TN concentrations from surface flow, respectively; the average concentration of TN from subsurface flow on GC was about 36–56% of that recorded from surface flow. Surface flow, interflow and groundwater flow contributed 0–15, 2–9 and 76–96%, respectively, of loss load of TN. Compared with BL, GC and LC intercepted 83–86% of TN loss through surface runoff; GC intercepted 95% of TN loss through subsurface flow while TN loss through subsurface flow on LC is 2.3 times larger than that on BL. In conclusion, subsurface flow especially groundwater flow is the dominant hydrological rout for N loss that is usually underestimated. Grass cover has the high retention of N runoff loss while litter mulch will increase N leaching loss. These findings provide scientific support to control N runoff loss from the red soil slope lands by using suitable vegetation cover and mulching techniques.     

Changes in the structure of differently tilled soil in a growing season

Changes in the structure of tilled soil over a growing season were investigated. Structural data from ten differently tilled plots were collected at the 40–50 mm depth on sectioned tilth block samples impregnated with paraffin wax. At the end of the growing season, significant increases in clod size and decreases in void size were observed. In some plots also a significant reduction in percentage of small (1–5 mm) aggregates was observed, but a crop cover (barley) increased the percentage of small aggregates.     

Spatio‐Temporal Patterns of Land Use/Cover Changes Over the Past 20 Years in the Middle Reaches of the Tarim River,Xinjiang, China

The interaction between land use/cover change and landscape pattern is pivotal in research concerning global environmental change. This study uses three different Landsat images of 1989, 1998 and 2009 to study the land use/cover and landscape pattern changes in the middle reaches of the Tarim River basin. envi ®, erdas ®, ArcGIS ® and fragstats ® software were used to analyse the land use/cover changes. The objectives of study were to map and study the changes in land use/cover and landscape pattern, and propose some possible factors in making the land use/cover changes from 1989 to 2009. Seven different types of land use/cover are analysed, and the results are listed in tables. From 1989 to 1998, the percentage of farmland, slight–moderate saline land, heavy saline land and water areas have increased; woodland, desert and the undeveloped land have decreased. From 1998 to 2009, farmland, heavy saline land and the undeveloped land have increased; the other types of land use/cover have decreased. The gravity centre of each land use/cover types has shifted. The farthest shifting of the gravity centre was heavy saline land, which occurred between 1989 and 1998. The transformation and changes of land use/covers and landscape occurred more frequently from 1989 to 2009. Other types of land use and land cover changes to saline land have increased, which implied that a serious salinization took place in the Tarim Basin. The results from this study would show the adverse environmental changes (e.g. salinization and desertification) and they can be used for future sustainable management of land resources. Copyright © 2013 John Wiley & Sons, Ltd.     

Complex pedogenesis related to differential aeolian sedimentation in microenvironments of the southern part of the semiarid region of Argentina

The aim of this paper is to explain soil genesis and spatial variability in the soil cover of a flat landscape in the southern part of Argentina's semiarid region. Soil survey data indicate random differences in the properties of soils lying within a few hundred meters of one another, as reflected in an intricate distribution pattern which cannot be explained by the climatic theory of soil genesis in a single pedogenetic cycle. This pattern is unrelated to the actual vegetation cover. The soil parent materials consist of a <2-m mantle of aeolian Holocene sediments overlying a thick plio-Pleistocene “tosca” layer (calcrete, caliche). The undulations in the tosca layer are indicative of a paleomicrorelief levelled up to the present surface after the deposition of the Holocene sediments. Soils with fine-textured sandy loess and strong development (Meridiano soil: A–Bw–Ck–2Ckm) occupied a higher position within paleomicrorelief of the tosca layer. Adjacent soils on border or intermediate positions of the petrocalcic paleosurface have more complex profiles with a relict calcic horizon (Vizcachera soil: A–C–2Ck–3Ckm) and coarser texture (silty clayey sand) in the topsoil. In the lower positions of the paleomicrorelief of the tosca layer, the silty clayey sand directly overlie the petrocalcic horizon (El Khazen soil: A–C–2Ckm). The intricate distribution pattern is due to the coexistence of older polypedon (Meridiano soil), remnants of an earlier erosion cycle complexed with two younger soils, one from partial erosion (Vizcachera soil) and the other where total erosion of earlier soils was followed by successive pulses of aeolian deposition (El Khazen soil). The distribution pattern of the three soils thus reflects a complex history involving at least three stages of landscape evolution.     

Cover‐crop seeding‐date influence on fall nitrogen recovery

Planting cover crops after corn‐silage harvest could have a critical role in the recovery of residual N and N from fall‐applied manure, which would otherwise be lost to the environment. Experiments were conducted at the University of Massachusetts Research Farm during the 2004–2006 growing seasons. Treatments consisted of oat and winter rye cover crops, and no cover crop, and four cover‐crop dates of planting. The earliest planting dates of oat and winter rye produced the maximum biomass yield and resulted in the highest nitrate accumulation in both cover‐crop species. The average nitrate accumulation for the 3 years in winter rye and oat at the earliest time of planting was 60 and 48 kg ha^–1, respectively. In 2004 where the residual N level was high, winter rye accumulated 119 kg nitrate ha^–1. While initially soil N levels were relatively high in early September they were almost zero at all sampling depths in all plots with and without cover crops later in the fall before the ground was frozen. However, in plots with cover crops, nitrate was accumulated in the cover‐crop tissue, whereas in plots with no cover crop the nitrate was lost to the environment mainly through leaching. The seeding date of cover crops influenced the contribution of N available to the subsequent crop. Corn plants with no added fertilizer, yielded 41% and 34% more silage when planted after oat and rye, respectively, compared with the no–cover crop treatment. Corn‐silage yield decreased linearly when planting of cover crops was delayed from early September to early or mid‐October. Corn‐ear yield was influenced more than silage by the species of cover crop and planting date. Similar to corn silage, ear yield was higher when corn was planted after oat. This could be attributed in part to the winter‐kill of oat, giving it more time to decompose in the soil and subsequent greater release of N, while the rapidly increasing C : N ratio of rye can lessen availability to corn plants. Early plantings of cover crops increased corn‐ear yield up to 59% compared with corn‐ear yield planted after no cover crop.     

Nitrogenase Activity and Nodule Biomass of Cowpea (Vigna unguiculata L. Walp.) Decrease in Cover Crop Mixtures

Legume cover crops are often used to build soil nitrogen (N) fertility and there is increasing interest in cover crop mixtures. The objective of this mechanistic greenhouse study was to determine the effect of cover crop community diversity and soil fertility on nitrogenase activity and nodule biomass of cowpea. Cover crops were grown for 42–53 days, aboveground biomass was harvested, and nitrogenase activity was estimated with the acetylene reduction assay. Roots were then excavated to determine nodule and root biomass. Nitrogenase activity and nodule biomass per plant were greatest in cowpea monoculture and reduced by 71–98 percent in four-species mixtures. Reduced capacity for N₂ fixation was partially driven by lower cowpea biomass in mixtures. The ratio of root nodule / shoot biomass increased by 81–297 percent in low-fertility relative to high-fertility soils, which contributed to increased nitrogenase activity. Results suggest cowpea monocultures in low-fertility soils have the greatest potential for N₂ fixation.     

Spatial distribution of rock fragments on steep hillslopes in karst region of northwest Guangxi,China

Rock fragments (> 5 mm in diameter) at the soil surface and within the topsoil have a large effect on the intensity of various hydrologic and geomorphic processes. However, little information is available on the spatial distribution of rock fragments in subtropical regions. The objective of this paper was to investigate the relationship between the spatial distribution of rock fragments and landforms on two different steep karst hillslopes in northwest Guangxi, southwest China. On the first hillslope (a disintegrated landslide failure) with the presence of several large rock outcrops (> 2 m in height), the spatial distribution of rock fragment cover had no obvious relationship with topographic position except that the mean cover percentage of small rock fragments (5–20 mm) decreased from bottom to top. On the second hillslope (an avalanche slope) without the presence of large rock outcrops, the mean total rock fragment cover (5–600 mm) increased from bottom (5%) to top (21%) with decreasing variability and rock fragments with various sizes (5–20, 20–75, and 75–250 mm) showed a similar increasing trend. The mean total rock fragment cover increased linearly with slope gradient on the second hillslope and tended to increase and then decrease with gradient but their relationship was not obvious on the first hillslope. This indicated that the spatial distribution of surface rock fragment cover had a close relationship with the presence of large rock outcrops and slope gradient. However, the median diameter (D₅₀) of the surface rock fragments had an increase–decrease trend with slope gradient but there was no obvious relationship on both hillslopes with low overland flow. Therefore, the dominant factor for the spatial distribution of rock fragment cover and size at the soil surface might not be soil erosion by water, but slope gradient, vegetation and geomorphologic condition of the slope. The mean total volumetric rock fragment content (5–250 mm) within the topsoil (10–20 cm thick) increased linearly from bottom (16%) to top (39%) with slope gradient on the first hillslope, and had a logarithmic increase from bottom (10%) to top (27%) with gradient on the second hillslope. This suggested that rock fragment content within the topsoil was mostly controlled by slope gradient and topographic positions and had not a close relationship with the presence of large rock outcrops.     

Influence of trees on soil organic matter in Mediterranean agroforestry systems: an example from the 'Espinal' of central Chile

The ‘Espinal’ agroforestry system of the Mediterranean zone of central Chile, which covers an area of 2000 000 ha, is in various stages of degradation due to human activities. The objective of our study was: (i) to determine the effects of the canopy cover of Acacia caven (‘Espino’) on total soil organic carbon (SOC), soil respiration and the labile components of soil organic matter (microbial biomass, and light fraction); and (ii) to determine the influence of ecosystem degradation on total and labile components of SOC. Soils of the study area are classified as fine, mixed, active, mesic Ultic Palexeralfs, typical of the Mediterranean‐type environment. We investigated sites according to the percentage coverage of A. caven canopy: (i) well‐preserved Espinal (WPE), 80–51% cover; (ii) good Espinal (GE), 50–26% cover; (iii) degraded Espinal (DE), 25–11% cover; and (iv) very degraded Espinal (VDE), < 10% cover. In addition, a site under native forest (NF) was included to characterize the original state of the zone. Soil samples were taken under and outside the canopy of A. caven at two depths, 0–5 and 5–10 cm. We conclude that the microbial biomass carbon (C_mic), and total and labile components of SOC are influenced by the presence of the A. caven tree, with greater values under than outside its canopy. Under the tree canopy, to a depth of 10 cm, C_mic was less under all the agroforestry systems than in NF (46 and 30% less for WPE and GE, respectively, and 67 and 57% less for DE and VDE). However, there was no clear trend for less C_mic with increased ecosystem degradation, especially outside the canopy. However, the respiration of microbial communities was affected by ecosystem degradation for both soil depths under the tree canopy, e.g. soil respiration in VDE ecosystems was about 50% greater than that found in WPE ecosystems. Increasing the coverage of the A. caven tree in the semiarid ecosystems of central Chile, e.g. changing from VDE to WPE, would result in an eventual, long‐term (over several centuries) increase in soil organic C of approximately 50%.     

Soils of the Pavlovsk Park (Saint Petersburg)

Eurasian Soil Science - Soils of the Pavlovsk Park–the largest landscape park in Europe—have been studied, and large-scale mapping of the soil cover of the main areas of the park has...     

Minerals in the three-component combination of agrochernozems in the Kamennaya Steppe

Properties and mineralogy of fine fractions separated from agrochernozems forming a three-component noncontrasting soil combination in the Kamennaya Steppe have been characterized. The soil cover consists of zooturbated (Haplic Chernozems (Clayic, Aric, Pachic, Calcaric)), migrational-mycelial (Haplic Chernozems (Clayic, Aric, Pachic)), and clay-illuvial (Luvic Chernozems (Clayic, Aric, Pachic)) agrochernozems. All the soils are deeply quasi-gleyed because of periodical groundwater rise. The mineralogy of the fraction <1μm includes irregular mica–smectite interstratifications, di- and trioctahedral hydromicas, imperfect kaolinite, and magnesium–iron chlorite. The profile distribution of these minerals slightly varies depending on the subtype of spot-forming soils. A uniform distribution of clay minerals is observed in zooturbated agrochernozem; a poorly manifested eluvial–illuvial distribution of the smectite phase is observed in the clay-illuvial agrochernozem. The fractions of fine (1–5 μm) and medium (5–10 μm) silt consist of quartz, micas, potassium feldspars, plagioclases, kaolinite, and chlorite. There is no dominant mineral, because the share of each mineral is lower than 35–45%. The silt fractions differ in the quartz-to-mica ratio. The medium silt fraction contains more quartz, and the fine silt fraction contains more micas.