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In order to compare the influence of different soil types and stratification on water infiltration capacity, two main types of soil in the desert steppe, sierozem (S) and aeolian sandy soil (A), were selected, and infiltration simulation tests were conducted on homogeneous soil and layered soil (layer thickness 5, 10, and 20 cm), respectively. The results show that during the whole experiment, there was a small difference between S5A95 (aeolian sandy soil 95 cm thick was covered with sierozem 5 cm thick) and S10A90 (aeolian sandy soil 90 cm thick was covered with sierozem 10 cm thick) in the wetting front process, infiltration rate and cumulative infiltration, but there was a significant difference between S5A95 and S20A80 (aeolian sandy soil 80 cm thick was covered with sierozem 20 cm thick). In the initial infiltration stage, there was no significant difference between A5S95 (sierozem 95 cm thick was covered with aeolian sandy soil 5 cm thick) and A10S90 (sierozem 90 cm thick was covered with aeolian sandy soil 10 cm thick). However, with the increase of infiltration time, the wetting front process, A5S95, A10S90 and A20S80 had significant differences in terms of wetting front process, infiltration rate and cumulative infiltration. The infiltration capacity of A was significantly higher than that of S. Combined with linear Ä2 value and model parameters, the three infiltration models were comprehensively compared, and the fitting process and results of the general empirical model for the infiltration process of homogeneous soil and layered soil showed good results. Three models were used to simulate the water infiltration process of layered soil with different textures, and the order of the effect is as follows; general empirical model > Kostiakov model > Philip model. Soil type and layer thickness had a great influence on water infiltration process. When sierozem was covered with aeolian sandy soil 20 cm thick, the infiltration capacity was the best. As aeolian sandy soil was covered with sierozem 10 cm thick, the infiltration effect was the worst. Therefore, once coarse graying occurs on the surface of sierozem (the thickness of sand is more than 20 cm) or when the content of fine particles overlying aeolian sandy soil (the thickness of silt and clay soil is more than 10 cm) during ecological restoration is high, the soil hydrological characteristics will change significantly, which may lead to changes in vegetation types and even ecosystem structure. [ABSTRACT FROM AUTHOR]

Current ware potato yields in the Netherlands are approximately 70% of their potential. It is hypothesised by several stakeholders within the potato value chain that part of the potato yield gap is caused by a lack of phosphorus (P) and potassium (K) application. In this study, we analysed for 46 farmers' fields if increasing P and K fertiliser application rates led to a higher yield and yield quality. We found that, on average, increased P and K fertiliser application did not result in a significantly higher yield for two currently cropped potato cultivars on two different soil types in the Netherlands (Innovator on clay soils and Fontane on sandy soils) and in two years (2019 and 2020). However, on sandy soils at relatively lower farmer K application rates, our K application led to a small positive yield response up to 5 t ha−1. On clay soils, there was an average positive yield response to our K application at lower yield levels of the control. For P, we did not find any correlation between yield response to P application and the amount of P applied by farmers or any of the measured soil parameters. In terms of yield quality, the K application led to a slight reduction in underwater weight on sandy soils in 2019 and a slight increase in the yield of large tubers in 2020. We conclude that, although in some fields there was a small positive yield effect of increased K application, increasing P and K application rates will not narrow the potato yield gap and improve potato yield quality in the Netherlands. Instead, increasing the P and K application will decrease P and K use efficiency and hence is not recommended from an environmental and economic perspective. [ABSTRACT FROM AUTHOR]

Compressed stabilized soil block is a sustainable building material primarily made up of stabilized damp soil compressed under pressure. Soil properties and the type of the stabilizer used in producing compressed soil blocks have a significant impact on the quality and behavior of the soil blocks. This study presents the physical and mechanical behavior of lime-cement-stabilized compressed interlock soil blocks produced from two types of natural soil. The two types of soil have different index properties and mineral oxide compositions. Lime-cement combination and cement standalone was used as a binder in the production of test sample blocks depending on the index properties of the soil. 2%lime + 6%cement, 3%lime + 8%cement, and 4%lime + 10%cement were used for the soil block produced from silty clay soil of medium plasticity index. On the other hand, 6%, 8%, and 10% cement by dry mass of soil were used to stabilize silty sand soil. The behaviors of the blocks, such as dry density, the initial rate of water absorption, saturated absorption of water, compressive strength, and stress-strain relation, were examined. The result shows that the compressed soil blocks produced from lime-cement-stabilized silty clay soil has a low rate of initial water absorption and a low dry unit weight when compared to cement-stabilized sandy soil blocks. Soil blocks produced from cement-stabilized silty sand soil attain greater compressive strength by more than 50% of the compressive strength of silty clay soil blocks stabilized by a combination of lime and cement at 60 days after production. The initial tangent modulus of the soil blocks produced using a manual compressing machine from a clay soil stabilized by the lime-cement proportions of 2%L + 6%C, 3%L + 8%C, and 4%L + 10%C is about 1,700 MPa–2,300 MPa with a dry density greater than 1,660 kg/m3. [ABSTRACT FROM AUTHOR]

Co-application of fertilisers and biofertilisers increases solubility and concentration of nutrient elements in the soil. However, information on the effect of P fertiliser and rhizobium inoculation on the concentration of mineral elements in the rhizosphere of field-grown chickpea in contrasting soil types is lacking. We assessed the effect of phosphorus fertiliser, rhizobium inoculation, and rhizobium inoculation plus P fertilizer on the concentration of nutrients in the rhizosphere of 2 chickpea genotypes (ACC#1 & ACC#5) at clay and sandy soil sites in two consecutive years. ACC#5 accumulated higher amounts of rhizospheric nutrients than ACC#1 in both soil types despite the variable response to fertiliser treatment. Rhizobium inoculation plus P fertiliser resulted in higher accumulations of rhizosphere N (7-219%), P (20-348%), K (9-365%), Ca (2-155%) and Zn (15-259%) compared to the other fertiliser treatments suggesting an additive effect of P fertiliser and rhizobium inoculation. Moreover, the effect of fertiliser treatments was more pronounced in the clay than the sandy soil. Our investigation is the first to document the effects of fertiliser treatment, genotype, and soil type on the accumulation of rhizosphere nutrients in field-grown chickpea. However, we propose further studies, incorporating more cultivars and environments, before making practical recommendations. [ABSTRACT FROM AUTHOR]

The selectivity and efficacy of protoporphyrinogen oxidase (PROTOX) inhibitor herbicides in cassava varieties depend on product formulation, dosage, and soil texture. The aim of this study was to assess the selectivity and efficacy of flumioxazin and sulfentrazone in the cassava variety 'IPR B36' and the clone 'VN 117'. Two experiments were carried out: one in a clayey soil and one in a sandy soil. Both experiments were laid in a split-plot randomized block design with three replicates. The two cassava varieties were used as main plots, with subplots consisting in 10 treatments including, flumioxazin at 50, 75, 100, and 125 g ha-1; sulfentrazone at 250, 500, 750, and 1000 g ha-1; one weed-free control, and one unweeded control. Flumioxazin (=75 g ha-1) and sulfentrazone (=250 g ha-1) achieved mean weed control rates > 70 and 90% in both types of soil for up to 90 days after application. Flumioxazin exhibited fewer residual effects on the cassava varieties than sulfentrazone, particularly in clayey soil. Flumioxazin was selective to the different cassava varieties planted in both soil types, whereas sulfentrazone was more selective in clayey soil. PROTOX inhibitors were effective in controlling weed growth in cassava plots, and there were no varietal differences in herbicide selectivity; however, the use of sulfentrazone should be restricted to maximum spray rates of 250 g ha-1 in sandy soils. [ABSTRACT FROM AUTHOR]

The priming effect (PE) induced by exogenous organic substrate input plays an important role in the soil carbon balance. However, little is known about how the chemical complexity of different exogenous organic substrates and soil type regulate the PE. Therefore, we conducted a 72-day incubation experiment involving the addition of three 13C-labelled substrates (glucose, starch and cellulose) to two forest soils with contrasting textures (i.e., a fine-textured clay soil and a coarse-textured sandy soil). Cellulose had a lag phase in the mineralization process but induced greater PE compared to glucose and starch in both soils. Moreover, exogenous organic substrate input generally induced negative PE and net soil C gain in the clay soil, but positive PE and net soil C loss in the sandy soil. The negative PE in the clay soil was negatively correlated with exogenous C mineralization, indicating that preferential substrate utilization was the mechanism controlling PE in the clay soil. However, the positive PE in the sandy soil was positively correlated with exogenous C mineralization, microbial biomass C (MBC), cellulase activity and soil inorganic N content, suggesting that co-metabolism was the mechanism regulating PE in the sandy soil. The significant difference in PE between the clay and sandy soils was mainly attributed to their significant differences in soil MBC, dissolved organic C (DOC) and SOC contents, followed by soil texture (particularly the clay content), available N content and pH. Overall, our results demonstrate that soil type is much more important than substrate type in regulating the PE and that the clay soil has a greater C storage potential than the sandy soil following the input of exogenous organic substrates. [ABSTRACT FROM AUTHOR]

A series of large scale direct shear tests was performed to obtain the shear strength interface parameters for five different geosynthetic reinforcement materials in marginal clayey sandy soil. The performance of geosynthetic layers was evaluated at soil optimum moisture content (OMC) and high moisture content (OMC+6%) conditions. It was observed that the shear strength interface parameters dramatically decreased at 6% wet of optimum in comparison with optimum moisture content. Moreover, a comparison was made between the performance of different geosynthetic layers in a quantitative manner at target moisture content (i.e., OMC+6%). Based on the analysis of large scale direct shear test results, it was concluded that the geosynthetic layer, provided it has high drainage capability, could effectively increase the interface shear strength parameters at OMC+6% condition. [ABSTRACT FROM AUTHOR]

The liquefaction phenomenon may originate in fine sandy - silty type of soils subjected to dynamic effects, low plasticity clays and even in soils with gravels based on the magnitude of applied acceleration. The mechanical or chemical soil improvement techniques have been used to prevent this problem. The mixing or grouting operations of sodium polyacrylate, which has a high-water absorption capacity, is one of the chemical soil improvement techniques. The frost behavior of this material, which turns into a gel form when react with the water in the environment, is not known in the permafrost areas. Within this purpose, sandy specimens including 5.00%, 10.00%, 15.00%, and 20.00% sodium polyacrylate gel as well as reference ones, were frozen at -20C° and unconfined compression tests were applied. Moreover, the tests were repeated for additional specimens containing 5.00% bentonite clay by weight. Although the unconfined compressive strength of all samples improved according to the increase in the amount of water with the gel content, about 14.00% lower values were obtained in specimens containing bentonite. On the other hand, the unit strain values of frozen samples without bentonite increased, while reduction observed in samples with bentonite. The viscous structure, that is in gel form inside the soil, dissipates volume increase during the freezing process and prevents the frost heave problem. However, the loss of bearing capacity should be considered in case of insufficient saturation in liquefaction sensitive sandy soils improved with sodium polyacrylate. [ABSTRACT FROM AUTHOR]

A generalized water retention curve (WRC) model in a wide suction range considering the initial void ratio is presented in this paper. Both capillary and adsorbed water in soil pores are considered. Based on the experimental results that the adsorbed water content w a is not dependent on the initial void ratio, a new degree of saturation equation of adsorbed water is established. Meanwhile, a new degree of saturation equation of capillary water at various initial void ratios is proposed with a void ratio-related expression of the air entry value. Compared to Lu's model, only one parameter b is introduced in the established model, which can be easily calibrated using WRCs under two initial void ratios. The measured WRC results of 5 soils are used to verify the proposed model in comparison with the other 3 widely used WRC models. The soil used in the model validation covers a wide range of soil types from sandy soil to clay soil, including clayey silty sand, sandy clay till, clayey silt, expansive soil and lateritic soil. The proposed model is well verified for its ability to describe soil water retention characteristics in a wide suction range at various initial void ratios. [ABSTRACT FROM AUTHOR]

Two field experiments were conducted to evaluate the effect of foliar application of salicylic acid (SA) on the growth, yield and quality characters of five sugar beet varieties (MARWA KWS, SUGAR KING, MiRAGE, DREEMAN and ESTORA KWS) under two types of soil in the two different locations in Nubaria and Sakha regions during 2018/2019 and 2019/2020 seasons. The experiments were conducted in split-split plot design in the three replications, where the main plots assigned by the two soil types (sandy soil in Nubaria and clay soil in Sakha), while the subplots were occupied by the three foliar application concentrations of SA (control, 1000 and 2000 ppm) and the five sugar beet varieties (Marwa kws, Sugar king, Mirage, Dreeman and Estora kws) were allocated randomly the sub-subplots. The results revealed that the foliar application of 2000 ppm SA significantly influenced the top fresh mass and root biomass of sugar beet plants. Conversely, the increasing concentration of SA led to significant differences in fresh mass, sugar yield, and sucrose % as well as purity % of sugar beet in both seasons. The Dreeman and Estora kws exhibited better performance in terms of root length under Nubaria conditions. The interaction effect between the three factors gave the maximum levels of increment for most of the studied characters, particularly for the cultivar ESTORA KWS. [ABSTRACT FROM AUTHOR]

This paper presents the influence of temperature on the residual strength by analyzing shearing tests carried out in a temperature- and velocity-controlled ring shear apparatus. Temperature was applied in steps of cooling and heating ranging between 6 °C and 50 °C at a constant shearing velocity of 0.442 mm/min. Additional tests include the evaluation of the strength at 0.890 mm/min before and after the imposed temperature change. Six basic soil types characterized by different mineralogy, grain size and plasticity, as well as, mixture soils having different proportions of sand and clay, are evaluated and the results are interpreted in terms of their properties. The experimental results reveal that the temperature effect becomes relevant when fine particles and plasticity increase being negligible in the case of the sandy soil. Shear strength reacts immediately to temperature changes and a new residual strength establishes soon. The temperature effect is symmetric. An increase in temperature leads to a decrease in strength, and an equal and opposite trend is observed when temperature decreases. The magnitude of the strength variation is significant in clayey soils. For the case of high plasticity soils, the residual friction angle variation observed during cooling and heating (±50 °C) is around 2°. The strain rate effect evaluated in a smaller number of tests indicated a strain rate strengthening in all the materials tested except for the case of the sandy soil, which also was not reactive to temperature changes. The experiments are calibrated with a velocity, state, and temperature-dependent friction model. • Influence of temperature on residual shear strength have been characterized. • Heating leads to decrease in friction and cooling leads to an increase for high shearing rates. • Relevance of residual friction change with respect of temperature correlates with the soil plasticity. • No effect of temperature was measured for the clean sand tested. • The friction constitutive model developed by Chester (1994) can reproduce the tests performed. [ABSTRACT FROM AUTHOR]

Natural and man-made slope failure has been a phenomenon that has caused many deaths, destruction, and environmental damage. The use of bioengineering technique (grasses) has been widely approached for slope remediation work. However, slope failure still occurs even though it has been protected by a few grasses. Many previous findings have reported on root pull out and root tensile strength for different plant species. However, the type of soil was not taken into account. Therefore, this research was carried out to investigate the function of root mechanical properties in different types of soil. The dry and wet sieve analysis tests were performed to know the classification of the soil. In addition to that, the soil mineralogy test was also conducted to support the soil classification. Root tensile strength tests were carried out on well-grown and poorly-grown Bermuda grass toward sandy and clay soil in dry and wet conditions. The dry condition is considered the condition of Bermuda grass in hot weather, while the wet condition is the condition after the raining season. Bermuda grass was chosen since this type of grass is widely applied for slope stabilization. The site locations were chosen in Temerloh, Maran which consist of clay soil. The other locations chosen were Karak, Gambang, Kuantan, Dengkil, Batang Kali, Ulu Yam, Kuala Pilah, Gombak and Sabak Bernam consist of sandy soil. The results show that the single root of Bermuda grass has higher tensile strength in sandy soil with range values from 0.47 to 185 Mpa compared to clay soil with range values from 0.12 to 159.10 Mpa. In conclusion, the results indicate that soil is one of the factors that influence the growth of bioengineering techniques for slope reinforcement. • A bioengineering method is being used as an alternative for slope stabilization. • The soil stability will increase with time as the root grows. • The pull out force was much affected by tensile strength. • In term of tensile strength, the value decreases with increasing root diameter. • Roots have a great impact on tensile and pull out strength. [ABSTRACT FROM AUTHOR]

Land application of biosolids can constitute an important source of triclosan (TCS) input to soils, with uncertain effects. Several studies have investigated the degradation potential of TCS in biosolids-amended soils, but the results vary widely. We conducted a laboratory degradation study by mixing biosolids spiked with [14C]-TCS (final concentration = 40 mg/kg) with Immokalee fine sand and Ashkum silty clay loam soils at an agronomic application rate (22 Mg/ha). Biosolids-amended soils were aerobically incubated in biotic and inhibited conditions for 18 weeks. Subsamples removed at 0, 2, 4, 6, 9, 12, 15, and 18 weeks were sequentially extracted with an operationally defined extraction scheme to determine labile and nonlabile TCS fractions. Over the 18-week incubation, the proportion of [14C] in the nonlabile fraction increased and the labile fraction decreased, suggesting decreasing availability to biota. Partitioning of TCS into labile and nonlabile fractions depended on soil characteristics. Less than 0.5% of [14C]-TCS was mineralized to carbon dioxide (14CO2) in both soils and all treatments. A degradation metabolite, methyl triclosan (Me-TCS), was identified in both soils only in the biotic treatment, and increased in concentration over time. Even under biotic conditions, biosolids-borne TCS is persistent, with a primary degradation (TCS to Me-TCS) half-life of 78 d in the silty clay loam and 421 d in the fine sand. A half-life of approximately 100 d would be a conservative first approximation of TCS half-life in biosolids-amended soils for risk estimation. Environ. Toxicol. Chem. 2011;30:2488-2496. © 2011 SETAC [ABSTRACT FROM AUTHOR]

This paper presents results of an analysis of a set of high-quality, side-by-side piezocone penetration test (CPTu) and standard penetration test (SPT) data for examining mechanical behaviour-based classification of soils. The results show that the soil behaviour type index ( ), either defined by Jefferies and Been (denoted herein as ) or by Robertson and Wride (denoted herein as ), is an effective parameter for mechanical behaviour classification. Additionally, an effort is made to find the most suitable cut-off (or boundary) value that can delineate cohesionless (sand-like) soils from cohesive (clay-like) soils. The Robertson and Wride's formulation, = 2·67 is found capable of delineating these two classes of soils. Similarly for the Been and Jefferies' formulation, = 2·58 is found to be the most suitable cut-off value for such classification purpose. These cut-off values for distinguishing sand-like soils from clay-like soils are found to be reliable in a case study of liquefaction susceptibility. [ABSTRACT FROM AUTHOR]

This study examined the effect of soil type on burrowing behaviour and cocoon formation during aestivation in the green-striped burrowing frog, Cyclorana alboguttata (Günther, 1867). Given a choice, frogs always chose to burrow in wet sand in preference to wet clay. Frogs buried themselves faster and dug deeper burrows in sandy soil. However, under my laboratory conditions, there was little difference in the pattern of soil drying between the two soil types. Frogs in both sand and clay soil experienced hydrating conditions for the first 3 months and dehydrating conditions for the last 3 months of the 6-month aestivation period, and cocoons were not formed until after 3 months of aestivation. After 6 months, there were more layers in the cocoons of frogs aestivating in sand than those aestivating in clay. Frogs were able to absorb water from sandy soil with water potentials greater than –400 kPa, but lost water when placed on sand with a water potential of –1000 kPa. [ABSTRACT FROM AUTHOR]

The damping-off incidence caused by Pythium aphanidermatum in chilli was 20.0 and 58.0% post-emergence at 7 and 20 days after sowing, respectively in clay soil. Among 4 different soils, clay soil favoured the disease most and recorded the maximum fungal population of 12.46×103 cfu/g of soil at 20 days after sowing. The incidence of disease was comparatively low in sandy soil. [ABSTRACT FROM AUTHOR]