Thermal diffusivity and temperature regime of soils in large lysimeters of the experimental soil station of Moscow State University

The thermal diffusivity of the upper horizons of model soddy-podzolic soils in the lysimeters depends on their water contents and varies within 2.1?4.32 × 10^?7 m²/s in the Ap horizon, 1.59?3.99 × 10^?7 m²/s in the B1 horizon, 1.28?3.74 × 10^?7 m²/s in the plowed B2 horizon, and 1.12?4.10 × 10^?7 m²/s in the B2 horizon. The dependence of the thermal diffusivity on the soil water content is described by an inverted parabolic curve for the Ap horizon, an S-shaped curve for the B1 and B2 horizons, and by a curve of transitional type for the plowed B2 horizon. The temperature regimes of model soils with different morphologies of the profile do not differ much and are close to the soil temperature regime under natural conditions on the plots of the weather station of Moscow State University.     

Thermal diffusivity of plowed leached meadow-chernozemic soils in the Adygeya Republic

Thermal diffusivity of the upper horizons of leached meadow-chernozemic soils varies in dependence on the soil water content within the following limits: 1.20–4.11 × 10⁻⁷ m²/s for the Ap horizon, 1.21–3.85 ×10⁻⁷ m²/s for the A1 horizon, and 1.35–3.73 × 10⁻⁷ m²/s for the A1B horizon. The relationships between the thermal diffusivity and the soil water content are described by S-shape curves with a long gently inclined segment within the range of water contents of <0.20 cm³/cm³, a distinct rise in thermal diffusivity within the water contents from 0.20 to 0.30–0.35 cm³/cm³, and a flattened or somewhat declining segment in the area with the high (>0.30–0.35 cm³/cm³) water contents. The thermal diffusivity of air-dried soil samples correlates with the physical clay (<0.01 mm) content. The Pearson correlation coefficient for these two variables equals −0.67 and is statistically significant at the significance level of 0.05. Regression equations allowing one to calculate the thermal diffusivity of the investigated soil horizons on the basis of data on the soil water content have been obtained.     

Modelling Thermal Diffusivity of Differently Textured Soils

A series of models has been proposed for estimating thermal diffusivity of soils at different water contents. Models have been trained on 49 soil samples with the texture range from sands to silty clays. The bulk density of the studied soils varied from 0.86 to 1.82 g/cm³; the organic carbon was between 0.05 and 6.49%; the physical clay ranged from 1 to 76%. The thermal diffusivity of undisturbed soil cores measured by the unsteady-state method varied from 0.78×10^–7 m²/s for silty clay at the water content of 0.142 cm³/cm³ to 10.09 × 10^–7 m²/s for sand at the water content of 0.138 cm³/cm³. Each experimental curve was described by the four-parameter function proposed earlier. Pedotransfer functions were then developed to estimate the parameters of the thermal diffusivity vs. water content function from data on soil texture, bulk density, and organic carbon. Models were tested on 32 samples not included in the training set. The root mean square errors of the best-performing models were 17–38%. The models using texture data performed better than the model using only data on soil bulk density and organic carbon.     

Dynamics of Sodium in Saline and Sodic Soils

Abstract

Soil salinization and sodication affect large areas of agricultural land in the world. Amelioration of these soils to make them suitable for agricultural production depends on understanding sodium dynamics and chemical interactions governing nutrient availability. Three locations in eastern Croatia were characterized to the 5‐m depth. The two solonetz‐solonchak soils were alkaline, whereas the solonetz soil had near‐neutral A/E horizon and alkaline deeper horizons. Electrical conductivity of the saturated extract (ECe) was greater than 4 dS m^?1 in the top horizons in the solonetz‐solonchak soils. The solonetz soil had 2.8–4.7 dS m^?1 in shallow A/E, CG, and G horizons and up to 6.3 dS m^?1 below 1.5 m. Highly alkalinized sodic horizons (exchangeable sodium percentage, ESP >20) had 24–47% Ca²⁺ and 27–33% Mg²⁺ on the cation exchange complex. Sodium adsorption ratio (SAR) was high (18–26) in the P horizon and even more so in Bt,na horizon (35–36) of solonetz‐solonchak soils. A strong negative exponential relationship existed between soluble Ca²⁺ and SAR (SAR increased greatly when Ca²⁺ dropped to around 3 mg dm^?3). An increase in pH to greater than 8.4 resulted in an exponential increase in SAR. Leaching of Na⁺ with successive volumes of water was similarly effective for the P and Bt,na horizons in the solonetz‐solonchak soils, but SAR remained greater than 15 even after six successive cycles of leaching. In conclusion, extensive amelioration of tested soils with gypsum and leaching will be required to overcome poor physical and chemical characteristics caused by various degrees of alkalization and sodication to bring these soils into production.     

Changes in the salt status of meadow-chestnut soils under the impact of saline groundwater in a model experiment

The continuous upward inflow and ascending capillary movement of sodium-sulfate groundwater through the profile of an initially nonsaline meadow-chestnut soil entail the displacement of exchangeable calcium by sodium in the lower Bca and BCca horizons; therefore, the content of sodium in the SEC increases to 60% and more. No unfavorable changes in the physical properties of the soils are observed because of the high salt concentration. Dissolved calcium is partially precipitated as calcite and gypsum in the Bca and BCca horizons and partially migrates, together with Cl^? ions, to the upper horizons with the ascending solution flow. In the Al horizon, Ca and Mg chlorides are accumulated as poorly crystallized strongly hydrated compounds, which give no peaks in X-ray diffraction patterns, and gypsum is deposited.     

Experimental Study of Factors Affecting Soil Erodibility

The effect of different factors and preparation conditions of monofraction samples from the arable horizon of leached chernozem on soil erodibility and its relationship with soil tensile strength (STS) has been studied. The exposure of samples at 38°C reduces their erodibility by two orders of magnitude. The drying of samples, on the contrary, increases their erodibility. It has been shown that erodibility decreases during the experiment. It has been found that the inoculation of soil with yeast cultures (Naganishia albida, Lipomyces tetrasporus) reliably increases the STS value in 1.5–1.9 times. The sterile soil is eroded more intensively than the unsterile soil: at 4.9 and 0.3 g/(m² s), respectively. The drying of soil followed by wetting to the initial water content (30%) has no significant effect on the STS value in almost all experimental treatments.     

Fractionation of Cu, Pb, Cr, and Zn in a Soil Column Amended with an Anaerobic Municipal Sewage Sludge

The objective of this study was to investigate the changes in the chemical partitioning of Cu, Pb, Cr and Zn within a column of soil incubated with an anaerobic sewage sludge (ANSS) for 2.5 months. The soil was irrigated during the incubation period. A sequential extraction method was used to fractionate these metals into exchangeable, weakly adsorbed, organic, Al oxide, Fe–Mn oxide, and residual, respectively. ANSS was applied at a loading rate of 69 Mg ha^?1. The soil is a Dystric Cambisol with low pH (<3.8), low CEC [<10 cmol(+) kg^?1 below the first 4 cm depth], and low base saturation (<7%). The addition of the ANSS caused a decrease in concentrations of Cu, Pb, and Cr in the A1 horizon, and an increase in the concentrations with depth. Below the A1 horizon, concentrations of Cu increased uniformly (~1 mg cm^?1), and the greatest increases were observed in the residual, Fe–Mn oxides, and weakly adsorbed fractions. Maximum increases in Pb occurred at 4–9 cm of depth (1.6 mg cm^?1), and mainly affected the weakly adsorbed fraction. Chromium essentially accumulated at the limit between the A2 and the Bw horizons (1.1–1.5 mg cm^?1) as residual and organic bound forms, probably through particulate transport. Zinc mainly accumulated in the A1 horizon (2.9 mg cm^?1) as exchangeable Zn. At depth, Zn increments were predominantly observed in the residual fraction. The results of this study thus demonstrate the redistribution of contaminants into different chemical pools and soil layers after sludge amendment.     

Mineralization of nitrogen compounds in a soil under an oxalis birch forest

The total mineralization of nitrogen in the AO-A1 (0–6 cm), A1 (6–11 cm), and A2 (11–21 cm) horizons of a soddy pale-podzolic soil under an oxalis birch forest in Yaroslavl oblast was measured from May to November in 2009 and 2010 and comprised 6.7 ± 0.9, 3.0 ± 0.4, and 5.5 ± 0.6 g of N/m² in 2009 and 5.6 ± 0.5, 2.5 ± 0.2, and 2.1 ± 0.5 g of N/m² in 2010, respectively. The total nitrification reached 0.4 ± 0.1, 1.1 ± 0.2, and 1.4 ±0.1 g of N/m² in 2009 and 1.0, 0.6, and 0.7 g of N/m² in 2010. Overall, the amount of mineralized nitrogen in the 21-cm-deep soil layer in 2009 and 2010 constituted 15.2 ± 1.1 and 10.2 ± 0.7 g of N/m², respectively. The contribution of nitrification to the nitrogen mineralization amounted to 20%. The seasonal variations in the soil temperature and moistening affected the concentrations of ammonium in the upper horizons and the accumulation of ammonium in the AO-A1 and A1 horizons. The combined effect of the temperature and moisture controlled the ammonification in the AO-A1 horizon (R = 0.83 at p = 0.16 in 2010), the nitrification in all the studied horizons (R = 0.86 at p= 0.13 in 2009), and the ammonia emission from the soil surface (R = 0.92 at p = 0.06 in 2010). A correlation between the seasonal dynamics of the ammonification and the CO₂ emission was found for the AO-A1 horizon (r = 0.64 at p = 0.16 in 2010) and was absent in the deeper layers of the soil profile. The nitrogen losses from the soil surface due to the ammonia emission in the investigated periods reached 95 ± 31 g of N/ha (2009) and 33 ± 30 g of N/ha (2010).     

In Situ Determination of Thermal Conductivity of Waste Rock Dump Material

In situ determinations of thermal conductivity of waste rock dumps at three mine sites: Aitik, Sweden; Kelian, Indonesia; and Heath Steele, Canada are described. Measurements were carried out at various locations and depths at each site. The estimated thermal conductivities range from 0.62 to 1.63 W m^-1K^-1 with an average of 1.21±0.27 W m^-1K^-1 for the waste rock pile at the Aitik site, 1.04 to 1.25 W m^-1K^-1 with an average value of 1.17(0.11 W m^-1K^-1 for the Heath Steele site, and 1.57 to 2.08 W m^-1K^-1 with an average value of 1.89±0.21 W m^-1K^-1 for the Kelian site. The higher average thermal conductivity at the Kelian site could be attributed to higher moisture content in the waste rock pile because of high rainfall at this site. Thermal diffusivity was also evaluated at a region of the Aitik waste rock dump where the thermal conductivity was also determined using measured temperature profiles. The thermal diffusivity value determined this way was (5.75 ± 0.75) × 10^-7 m²s^-1, consistent with that calculated from the thermal conductivity values determined for the same location.     

Mineralization of nitrogen compounds in the soil under the bilberry-sphagnum birch forest (Yaroslavl Oblast)

Net mineralization of nitrogen was measured in the horizons of peaty podzolic gley soil (At1, 0–6 cm, At2, 6–10 cm, and A2, 10–20 cm) of the bilberry-sphagnum birch forest from May to the beginning of November in 2011 and 2012; it comprised 2.1 ± 0.4, 2.7 ± 0.4, 1.2 ± 0.4, and 1.9 ± 0.2, 1.9 ± 0.2, 0.8 ± 0.15 g N/m², respectively. The total of 6 ± 0.7 and 4.6 ± 0.3 g N/m² were mineralized in the soil profile in the years 2011 and 2012, respectively, with the contribution of ammonification being more than 99%. The seasonal variations in nitrogen mineralization correlated with the temperature and soil moisture content in At1 and At2 horizons. The efficiency of nitrogen mineralization in soil horizons under the birch forest was expressed by similar values, namely, 0.005 ± 0.0008, 0.0064 ± 0.0008, and 0.003 ± 0.001 mg N/g C per day, and this suggests a high efficiency of substrate utilization in the eluvial part of the soil profile. The seasonal variation of carbon dioxide production correlated with the ammonification in the At1 horizon with r = 0.85 and p = 0.03 in 2011 and 2012, and in the At2 horizon with r = 0.65 and p = 0.16 in 2012. Over the studied period, production of ammonia depended on soil moistening in the dry year of 2011 (r = 0.91; p = 0.01) and soil temperature in the wet year of 2012 (r = 0.78; p = 0.06). The productivity of the process equaled 3 ± 0.9 mg N/m², or 30 g N/ha in both years of observation.     

Measuring the millimetre-scale oxygen diffusivity in soil using microelectrodes

The diffusivity of oxygen in soil was measured by periodically changing the gas above a soil core from nitrogen to air and vice versa. The concentration wave was measured as a function of depth with an oxygen electrode. For different Fourier components in the signal, phase shifts were calculated. The diffusivity follows from the increase of the phase shift with depth. Phase shifts are more suitable than signal amplitudes for the derivation of diffusivity. They are also easier to measure and do not require electrode calibration. For a clay soil with an air–filled porosity of about 0.05 m³ m^?3 a local diffusivity of 0.9 × 10^?9 m² s^?1 was measured. This is several orders of magnitude smaller than macroscopic values for entire core samples of the same soil type. This low value can be explained by the presence of locally water–saturated clay.     

Mineralization of nitrogen compounds in soils of south-taiga ecosystems

The productivity of the nitrogen mineralization in the A0 (0–2 cm), A1 (2–3 cm), and A2 (3–13 cm) horizons of a soddy-podzolic soil was measured in a wood-sorrel-whortleberry birch forest (7Birch3Asp, 80 years, the second stand quality class, tree canopy density 0.7, Yaroslavl oblast) using the sample incubation method; the measurements were performed from May till October in eight replicates for each horizon. In 2007, 5.85 ± 0.73 g N/m² were mineralized in the soil. In the litter, 2.01 ± 0.23 g N/m² were mineralized, whereas 0.35 ± 0.03 and 3.49 ± 0.72 g N/m² were mineralized in the A1 and A2 horizons, respectively. In 2008, 3.34 ± 0.25 g N/m² were mineralized in the A0 and A1 horizons, of which 2.44 ± 0.23 g N/m² were in the former. Ammonification prevailed in all the horizons. The contribution of nitrification was assessed as 1.6 and 0.3% of the process’s productivity in 2007 and 2008, respectively. The C_org and N_org pools decreased in the litter by 407 g C/m² and 13.7g N/m² (or 33%) from May to October. Of this carbon amount, 67% is spent for humification and the organic mass preservation and 33% was transformed to carbonic acid. The nitrogen expenses for the synthesis of humus acids are equal to 70 and 30%; it is spent equally for the mineralization of the element and its immobilization by microorganisms. In the A0 and A1 horizons, the seasonal trends of the ammonification correlated with the carbon dioxide emission from these horizons in the year of 2008 with r = 0.75 atp = 0.09 and r = 0.82 atp = 0.04 for both horizons, respectively.     

太湖流域水生态系统服务及其空间差异

以太湖流域土地利用资料、水文水质资料和统计资料为基础,对流域尺度上水生态系统服务功能及其空间差异性进行了评价与分析。结果表明,太湖流域水生态系统的水供给功能为3.70×1010 m3/a,水产品功能为6 681.180t/a,水路旅客周转量为4.604×108人/(km.a),水路货运周转量为2.90×1011t/(km.a),蓄水总量为4.53×109 m3/a,调节水量为7.69×109 m3/a,固碳量为4.28×106 t/a,释放O2量为1.14×107 t/a,净化污水量为6.30×109 t/a,年输沙量为1.22×106 t/a,造陆面积为189.851hm2/a;水生态系统服务功能总价值为9.10×1010元/a,不同服务功能价值量排序为:旅游>航运>调蓄>水质净化>固碳释氧>水供给>水产品>输沙造陆;太湖流域单位面积水生态系统服务功能价值为19.22元/(m2.a),且存在较大空间差异,其顺序为:浦西区>武澄区>浙西区>杭嘉湖区>湖西区>阳澄区>太湖区。     

Studies on the properties of organic matter in buried humic horizon derived from volcanic ash

Abstract

Humic acids were extracted from the surface horizon Yu 1 and buried humic horizons (Yu 2, 800-864 AD; Yu 4, ca. 4,000 years B.P.; Yu 6, 7,000 years B.P.; Yu 7, ca. 10,000 years B.P.). The humic acids were filtered with ultramembranes with 20, 10, 5, 1 or 0.1 × 10' M.W. in this order and separated into five fractions; (>20), (20-10), (10-5), (5-1) and (1-0.1) × 10⁴ M.W. fractions. The elementary composition, functional groups, optical properties, and hydrolyzable total- and sugar-carbon contents of each humic acid fraction were determined, and the changes in properties of the humic acid with age after burial were discussed.

In horizons Yu 1 to Yu 6, the patterns of M.W. distribution of the >20 × 10⁴ to (1- 0.1) × 10⁴ fractions were rather similar. In contrast, Yu 7 was characterized by the predominance of (1-0.1) x 10' M.W. fraction and the presence of a small amount of <0.1 × 10⁴ M.W. fraction.

The chemical properties of humic acid (HA) fractions of each humic horizon and their changes with age after burial were as folIows:

1) Elementary composition of HA fractions of each humic horizon was rather similar to each other. The C% and C/N ratio increased, and the H%, N% and H/C ratio decreased in all HA fractions with age.

2) Total acidity and carboxyl contents of HA fractions of Yu 1 were higher in the lower M.W. fractions. These values increased with age up to Yu 4 or Yu 6 horizons, then decreased in the Yu 6 or Yu 7 horizon. The contents of carbonyl groups in all the HA fractions which were very low in Yu 1, showed a wide range of variations in Yu 2, intermediate values from Yu 4 to Yu 6 horizons then decreased in the HA fractions of Yu 7, except for the (>20) fraction.

3) The degree of humification of the HA fractions of Yu 1 judging from the RF and \sDlogK values, tended to be higher in higher M.W. fractions, and increased in all the HA fractions with age after burial.

4) Hydrolyzable total- and sugar-carbon contents were high in the HA fractions of Yu 1 and decreased with age.

5) Changes of elementary composition, degree of humification and hydrolyzable total- and sugar-carbon contents were conspicuous from the Yu 1 to Yu 2 horizons, and less significant afterwards.

6) The 0%, C/O ratio and phenolic OH content did not show any consistent change with age after burial.     

Contribution of separate solid-phase components to the formation of the cation exchange capacity in the main genetic horizons of meadow-chestnut soils

Different types of cation exchange capacity (CEC) and related chemical properties were determined in the main genetic horizons of meadow-chestnut soils in the mesodepressions at the Dzhanybek Research Station of the Institute of Forestry of the Russian Academy of Sciences. In the A horizon, the CEC is mainly due to the organic matter from the clay and coarse fractions, which provides 36% of the soil CEC, and to labile silicates and other clay minerals of the clay fraction. In the Bt horizon, the CEC is mainly provided by the labile minerals of the clay fraction and organic matter of the clay and coarse fractions. The standard soil CEC was found to be significantly higher than the sum of the exchangeable cations in the A horizon and slightly lower than the sum of the exchangeable cations in the Bt and Bca2 horizons. This difference can be related to the fact that the NH₄⁺ ion, which is selectively adsorbed by clay minerals, is used as a displacing cation during the determination of the exchangeable bases, while the Ba²⁺ ion, which is more selectively adsorbed by organic matter, is used during the determination of the standard CEC. In all the genetic horizons, the experimentally determined value of the standard CEC almost coincides with the CEC value obtained by summing the standard CECs of the different particle-size fractions with account for their contents; hence, this parameter is additive in nature.     

Decomposition of clay minerals in model experiments and in soils: Possible mechanisms, rates, and diagnostics (analysis of literature)

The analysis of model experiments on the dissolution of clay minerals showed that, beginning from a certain moment, this process reaches a steady state and proceeds at a constant rate. The minimum dissolution rate was observed in a neutral environment, where this value varied in the range from n × 10^?14-n × 10^?12 mol/(m² s). Under acidic and alkaline conditions, this value increased to n × 10^?12 or n × 10^?10 mol/(m²s) for most clay minerals. The first stage of the dissolution mechanism involved the formation of protonated (in an acidic environment) and deprotonated (in an alkaline environment) complexes, which destabilized and polarized metal-oxygen (or metal-hydroxyl) bonds in the crystal lattice. At the second stage, the rupture of Si-O and Al-O bonds and the release of these components into the solution occurred at a specific concentration of these complexes, and this stage largely controlled the dissolution rate of the mineral. The presence of organic ligands forming mononuclear polydentate complexes on the surface of the mineral particles at the same solution pH increased the dissolution rate of the minerals by several times and sometimes by an order of magnitude proportionally to the concentration of these complexes on the surface of the particles. It was found that the dissolution rates of kaolinite, illite, and smectite in the podzolic horizon of loamy podzolic soil calculated from the losses of clay minerals in the soil profile with consideration for the soil age exceeded the corresponding values obtained in model laboratory experiments at the same pH values by several orders of magnitude. The revealed differences could be related to the long-term functioning of biota in native soils and the existing uncertainties in the assessment of the active surface of mineral particles.     

Soil Ammonium Diffusion Constraints Contribute to Large Differences in Nitrogen Supply to Rice in the Southern United States

This study was to determine if diffusion of soil ammonium may explain why many sandy soils have greater nitrogen (N)–supplying capacity to rice than clay soils. A laboratory procedure using transient-state methods measured the linear movement of soil ammonium (NH₄) in tubes packed with five field soils under aerobic conditions. Ammonium diffusion was measured by sectioning tubes after 48 h of equilibration and then measuring NH₄ by steam distillation. Effective diffusion coefficients, D_e, and NH₄ diffusion distance, d, per day ranged from D_e = 4.6 × 10^?5 cm² d^?1 and 1.5 cm d^?1 for Katy sandy loam to D_e = 2.9 × 10^?7 cm² d^?1 and 0.11 cm d^?1 for League clay. Ammonium diffusion distance d was strongly related to soil clay content and hence was predicted by d = Y × {[100/(% clay)] ? 1}, where Y is set to 0.1. Predicted d and measured d were highly related (R² = 0.99).     

Microsite assessment of forest soil nitrogen,phosphorus, and potassium supply rates in‐field using ion exchange membranes

Abstract

A new method for microsite assessment of soil nutrient supply in forest soil was developed. The method involves the use of ion exchange membranes to assess differences in soil nitrogen (N), phosphorus (P), and potassium (K) supply rates in‐field over small depth increments in the forest floor (i.e., the L, F, and H horizons). Ion exchange membranes were buried and retrieved from the forest floor in an aspen forest stand in Saskatchewan, Canada. Small (6 mm diameter) sections of the membrane were cut out and ion concentration on the sections measured to provide a nutrient supply rate at that location. Soil nutrient supply rates at the site ranged from 4.6–6.0, 7.3–8.5, 11.6–21.5, and 122–196μg 10 cm²#lb2 h^‐1 for NH₄ ⁺‐N, NC₃ ^‐‐N, P, and K, respectively. On average, the highly humified H horizon had the highest N and P supply rates, followed by the F horizon, with the surface litter (L horizon) having the lowest N supply rates. The simplicity and sensitivity of the procedure make this method appropriate for in‐field assessment of differences in soil nutrient supply over small vertical and horizontal distance and was especially appropriate for the forest floor horizons in forest soils.     

Radiological maps for fallout 7Be in forest soil horizons in a mountainous area of Turkey

Due to the paucity of data on separate spatial distribution of cosmogenic ⁷Be radionuclide activities in forest soil layers, a spatial study was performed in Mount Ida (Kazdagi)/Edremit, Turkey. In this study, it was aimed to examine the ⁷Be spatial variability and depth distribution in the surface soil layers. The ⁷Be activity concentrations were determined by HPGe gamma spectrometry system and the distributions of ⁷Be activities in the O_L and O_F + O_H horizons throughout the region were mapped separately. Activity concentrations of ⁷Be in O_L horizons and O_F+O_H horizons varied as 35 ± 23–701 ± 40 Bq kg^?1 and 0.96 ± 0.63–197 ± 11 Bq kg^?1, respectively. ⁷Be inventories (0.20 ± 0.06–5.69 ± 0.75 kBq m^?2) in the study area were relatively higher when compared with the other regions of the world. ⁷Be inventories increased with altitude, slope and the thickness of the humus layer in some of the investigated area. Average ⁷Be activity level in deciduous forest stand type was significantly higher than that for coniferous and mixed stand types. Our limited data could not provide a latitudinal distribution pattern of ⁷Be soil inventory or precipitation dependence and further investigation is needed.     

SW—Soil and Water: Improvement of Whitish Oasis Soil, Part 1: Field Experiments with a Four-stage Subsoil Mixing Plough

A prototype four-stage subsoil mixing plough was designed in Japan and built in China for the improvement of whitish oasis soil. The machine was transported to two places in China for field tests where the whitish oasis soil is found. This paper presents the trash mixing rate into mixed layer of Bca and C horizons, the inverting rate of the Bca and C horizons and the draught of the plough in the whitish oasis soil.The results show that the rolling resistance of the tracked vehicle (T802), on which the plough was mounted, was about 8 kN and the draught of the first plough body which tilled the Ap horizon was about 4 kN with a working depth of 200 mm and a working width of 500 mm. The draught of the second plough body, which tilled the surface of the Ap horizon, was about 2 kN with a working depth of 50 mm. The draught of the third plough body increased steeply with greater working depths. The draughts were about 8, 14 and 24 kN, respectively, for working depths of 117, 239 and 300 mm. The draught of the fourth plough body also increased steeply with greater working depth. The draughts were about 7, 14 and 18 kN, respectively, for working depths of 117, 178 and 239 mm. When the whitish oasis soil was disturbed by the plough bodies, it was observed that the whitish oasis soil was very hard but comparatively brittle and easily broken up. This property explains the smaller draught requirements in the whitish oasis soil despite a greater soil strength. The values of the soil-inverting rate ranged between 0·45 and 0·6, and the average value was 0·5. Perfect inversion of the Bca and C horizons was not possible, but good mixing was achieved by the plough. The average trash mixing rate in Inner Mongolia was 0·85, and that in North of River was 0·95. These data show that even in Inner Mongolia where the trash material is long, a fairly uniform trash mixing was possible.