Soil Particle Size Composition Research Articles

Successive monoculture of Eucalyptus spp. alters the structure and network connectivity, rather than the assembly pattern of rhizosphere and bulk soil bacteria

Eucalyptus as a fast-growing timber tree plays a crucial role in maintaining wood supplication and ecosystem balance worldwide. Nonetheless, the management practices of Eucalyptus plantation in southern China have resulted in productivity decline and soil degradation due to high-intensity successive cultivation. Soil bacteria is a sensitive indicator of soil quality, how does the successive planting of Eucalyptus regulate the soil bacterial community structure for instance the abundance of oligotrophic bacteria, network complexity, and soil bacteria assembly remain ambiguity. To explicate the underlying influencing mechanisms of successive cultivation of Eucalyptus plantations on soil bacterial community structure. Four harvests of Eucalyptus plantations that underwent 0, 1, 2, and 3 times of harvesting were conducted to examine variations in the bacterial community between rhizosphere and bulk soils after successive planting of Eucalyptus. An adjacent evergreen broadleaf forest was employed as control. The present study revealed that successive planting of Eucalyptus increased and reduced the relative abundance of Chloroflexi (oligotrophic bacteria) and Proteobacteria (copiotrophic bacteria), respectively. Continuous planting of Eucalyptus did not modify the assembly pattern of soil bacterial communities, which was governed by stochastic processes. Successive planting of Eucalyptus decreased co-occurrence network complexity, and elevated the proportion of rare microorganisms in the keystone bacterial taxa. Soil particle size composition (clay, silt, sand) indirectly influenced the structure of soil bacterial communities by directly affecting pH, carbon, nutrients, and their stoichiometric ratios. Improving soil physical structure, increasing the input of soil carbon, nitrogen, and other nutrient resources, and maintaining a balanced resource allocation may be effective strategies for ensuring enhanced productivity and sustainable utilization of soil in successive Eucalyptus plantations.

Long-term effects of conventional cultivation on soil cation exchange capacity and base saturation in an arid desert region

Land reclamation and subsequent management affect soil condition, which is critical for sustainable agricultural production. Soil cation exchange capacity (CEC) and base saturation (BS%) play an important role in the assessment of soil fertility and buffering capacity. However, the variation of these indicators in the evolution of oasis farmland in arid desert areas remains unclear. Therefore, this study was carried out aiming to evaluate the effect of desert reclamation and following long-term conventional cultivation on the CEC and BS%. For the study, we investigated the CEC and exchangeable bases (ExBas) content in oasis farmlands along a chronosequence (0–100 years) of cultivation in arid region and identified the key factors affecting CEC and BS%. The results showed that soil CEC and ExBas significantly increased after desert reclamation, whereas the BS% dramatically decreased. However, all these changes were alleviated with the conventional cultivation age. Regression analysis showed that soil CEC, ExBas, and BS% all exponentially changed with cultivation years. Based on our findings, CEC and ExBas were closely related to soil particle size composition, total nitrogen (TN), soil organic matter (SOM) and soil water content (SWC). The multiple stepwise regression further indicated that the changes in CEC and ExBas after reclamation mainly depended on the silt content, SWC, SOM, and TN. Our findings highlight that although desert reclamation increases soil CEC and ExBas in arid area, this effect tends to disappear after about 100 years of conventional cultivation, and meanwhile, the decline in BS% due to increased acids should also be noted.

Exploring a path of vegetation restoration best suited for a photovoltaic plant in the Hobq desert

To investigate the soil improvement effects of different vegetation restoration measures during the operation and maintenance of photovoltaic power plants in the Hobq Desert. This study determined the soil grain size composition and soil nutrient content of 0–5 cm under four vegetation restoration measures and within the mechanical sand barriers by laser diffraction techniques and chemical experiments. The results showed that: (1) Soil particle size composition in the study area is predominantly sandy, with 1.02%, 6.63%, 5.34% and 2.61% less sand in Leymus chinensis (YC), Glycyrrhiza uralensis (GC), Artemisia ordosica Krasch (YH) and Hedysarum scoparium (HB), respectively, compared to mechanical sand barriers (CK). Soil particle distributions of YC, GC, and HB showed better sorting and more concentrated patterns, and all four vegetation restoration measures had higher fractal dimensions than CK. (2) AN (Alkali-hydrolyzable Nitrogen) content performance: The content of YC, GC, and HB was significantly higher than that of YH and CK, AP (Available Phosphorus) content did not differ significantly between measures, AK (Available Potassium) content was higher than that of CK in all measures, with YC content being the highest and SOM content being the highest for GC. (3) Soil total nutrient is unstable across vegetation restoration measures. Overall, the performance showed that the three vegetation restoration measures, YC, GC, and HB, were more evident in the soil total nutrient content improvement. Each particle size characteristic parameter and soil nutrient response vegetation restoration measures ameliorate sandy soil in PV power plants during operation and maintenance. YC and GC have the most apparent effect on soil amelioration.

Comprehensive Effect of Soil Particle Size Composition and Wind Speed on Dust Emission Efficiency

AbstractRecent studies have shown that the dust emission efficiency (Ed) of some soil surfaces undergoes changes with wind speed and that such changes are related to soil properties. Through wind tunnel experiments, we investigate the comprehensive effect of soil particle size composition (PSC) (both minimally and fully dispersed) and friction wind speed (u*) on Ed. Results show that Ed initially increases and then decreases as soil texture changes from fine to coarse, with intermediate‐textured soils having the highest Ed and the strongest dust emission ability. The ratio of silt to sand in soil is an index suitable for reflecting the influence of soil texture on Ed. The PSC of soil dry aggregate is a factor that directly determines Ed. With increasing u*, Ed tends to increase for coarse‐ and intermediate‐textured soils but not for fine‐textured soil, supporting the view that Ed is influenced by u* and that the influence is related to soil PSC. Despite the fitting power function equations between Ed and u* for some soils failing to pass the significance test in this study, the substantial influence of soil texture on the power exponents implies potential for establishing an equation capable of expressing the comprehensive effect of soil texture and u* on Ed.

Characteristics of Soil Erodibility in the Yinna Mountainous Area, Eastern Guangdong Province, China

Soil erodibility research is of theoretical and practical significance to the prediction and prevention of regional soil erosion. At present, the study on soil erodibility in the lateritic red soil area of eastern Guangdong province is relatively lacking. Taking the forest land soil of the Yinna mountainous area as the research object, the physical and chemical properties (organic matter mass fraction, texture, moisture, bulk density, pH, aggregate content) of soil samples at different altitudes were measured with field survey sampling and indoor analysis. Soil erodibility K values were simulated with different models (the EPIC model, the Torri model, and the Shirazi model) and the regional applicability of the K simulation models was discussed. The influence of soil properties on soil erodibility was analyzed. The results showed that: (1) K values in the Yinna mountainous area are between 0.0250 and 0.0331 t·hm2·h/MJ·mm·hm2, and the K value in the subsoil layer (20-40 cm) is higher than that of the topsoil layer (0-20 cm). These values decreased significantly with the increase of altitude. The soil in the study area belongs to low-medium to medium erodible soil types. (2) The three models have certain applicability in the Yinna mountainous area, but the simulation results still lack validation. (3) Soil particle size composition is the most important factor affecting the K value in the study area. As far as the topsoil is concerned, K values increase with the increase of clay and silt content and decrease with the increase of sand content and aggregate stability. Soil erodibility has no significant correlation with pH and bulk density and has no clear relationship with the content of soil organic carbon and soil moisture. The research results can provide basic data for regional soil and water conservation and the construction of K value databases of different soil types in China.

High-resolution mapping and driving factors of soil erodibility in southeastern Tibet

Quantifying the spatial distribution of soil erodibility (K factor) in the Qinghai-Tibet Plateau is essential for global soil erosion management. However, many K factor maps have a coarse spatial resolution at the regional scale, and high-resolution mapping is still a challenge. Quantitative analysis of the influence of environmental factors such as soil, topography, climate, and vegetation, and human activities on the K factor is also lacking. Therefore, we mapped the high-resolution (90 m) spatial distribution of the K factor values in southeastern Tibet using a random forest model with multiple environmental variables, based on remote sensing, ground observations (114 sampling points), and gridded datasets. The K factor estimates based on soil particle size composition and organic carbon content ranged from 0.09 to 0.35, showing moderate variation. The random forest model yielded a coefficient of determination > 0.9 and provided detailed information on the spatial distribution of K factor values, especially in large unsampled areas. The predicted K factor values tended to be high in the eastern area and low in the western area. Partial least squares path modeling showed that soil physical properties such as fractal dimension and mean weight diameter of aggregates had the largest influence on the K factor (path coefficient 0.695). Climate and topography also had a considerable influence on the K factor (path coefficient −0.489 and −0.469, respectively), while the influence of vegetation and human activities was minimal. Accordingly, the random forest model is an effective tool for high-resolution spatial distribution mapping of the K factor with limited sampling data.

Effects of shell sand content on soil physical properties and salt ions under simulated rainfall leaching

To reveal the influence of shell sand content on soil physical properties and salt ion changes under simulated rainfall leaching conditions, various ratios of shell sand to fluvo-aquic soil were simulated to change the particle composition of shell sand. Basic physical and chemical properties, such as soil particle-size composition, soil bulk density, soil porosity, soil pH, soil electrical conductivity, and soil salt ions were determined and analyzed. Fuzzy mathematics was used to evaluate the potential for soil water storage and salt suppression by altering the shell sand-to-fluvo-aquic soil ratio. The results showed that with decreasing shell sand content, the soil particle composition with different ratios of shell sand to fluvo-aquic soil changed significantly. With decreasing shell sand content, bulk density and capillary porosity of the soils with different ratios increased, and the total porosity and noncapillary porosity decreased. The soil pH first decreased and then increased, following the order 0:1 > 1:0 > 1:1 > 1:2, while the electrical conductivity increased. Cl−, NO3−, Na+, Ca2+, and Mg2+ showed a trend of first decreasing and then increasing with decreasing shell sand content, following the order 0:1 > 1:0 > 1:2 > 1:1. The mixed soil with a 1:1 ratio of shell sand and fluvo-aquic soil has the largest leaching loss of salt segregants. A comprehensive evaluation of the soil improvement performance with respect to the ratio of shell sand to fluvo-aquic soil revealed a trend of 1:1 > 1:0 > 0:1 > 1:2, and the mixed soil with a 1:1 ratio of shell sand to fluvo-aquic soil showed the greatest improvement. The shell sand content can significantly affect soil water and salt transport, and a suitable shell sand content can effectively improve soil water storage and salt inhibition effects.

Spatial variability of soil properties in fixed sand dunes of the Eastern Ningxia Province

As sand dunes gradually become fixed, soil particle size, soil organic carbon (SOC) and total nitrogen (TN) contents vary across different locations of the dunes. To investigate the spatial variation of soil particle size distribution and soil nutrition in the fixed sand dunes, we examined particle composition, SOC and TC features in different locations of dunes in the Eastern Ningxia. The results showed that the particle sizes of each soil layer were mainly characterized by medium and coarse sands. The SOC and TN contents were higher in surface soil layers, with a maximum of 5.781 and 0.412 g·kg-1, respectively, which were observed in interdune lands and dune ridges, while the leeward slope of the dunes showed the least. The SOC content of both the leeward and windward slope gradually decreased with increasing soil depth along the dune. By contrast, that of the interdune lands decreased first and then increased. At small scale, both the SOC and TN contents showed a clear spatial heterogeneity. There was a positive correlation between soil nutrition contents (SOC and TN) and silt and very fine sand contents in the fixed sand dunes, and a negative correlation with medium and coarse sand contents. Our results implied that soil particle size composition influenced SOC and TN contents. The contents of soil nutrition increased with increa-sing contribution of fine particles, highlighting the role of fine particles in adhesion and accumulation of organic matter.

Soil detachment capacity by rill flow for five typical loess soils on the Loess Plateau of China

The loess region of China is one of the most heavily eroded areas in the world. Soil detachment capacity by rill flow (Dc) is a key parameter for quantifying intensity of rill erosion in many process-based erosion models. However, only a limited number of studies have been devoted to soil detachment capacity for the various types of loess soil such as is found on the Loess Plateau, where there is variation from south to north and in terms of soil particle size composition. The objectives of this study were (1) to discriminate differences in soil detachment capacity by rill flow (Dc) among five loess soils, (2) to investigate the relationship between Dc and hydrodynamic parameters, and the relationship between Dc and soil properties, and (3) to establish an equation to model soil detachment capacity by rill flow for the loess region. Soil detachment capacity by rill flow for five typical loess soils found on the Loess Plateau of China was investigated through a flume experiment by varying five flow discharges and five slope gradients. The results show that Dc of SM sandy loess is the largest with a mean of 2.2145 kg m−2 s−1, followed by YL clay loess, DB sandy loess, AS loess, and CW loess. Stream power is the best hydrodynamic parameter to describe the dynamic process of soil detachment capacity by rill flow for these five loess soils. Soil detachment capacity by rill flow was negatively correlated with soil cohesion and effective silt content (P < 0.05), while it was positively correlated with effective median soil particle size (P < 0.01) and effective sand content (P < 0.05). Soil detachment capacity by rill flow for various hydraulic and soil conditions in the loess region could be modeled using a quaternary power function of slope gradient, flow discharge, soil cohesion and effective median particle size (NSE = 0.96), or it could be modeled by a ternary power function which calculates the variation of soil detachment capacity with stream power, soil cohesion and effective median size (NSE = 0.96). The results of this study reveal the mechanism of soil detachment by rill flow and advance development of a physically-based rill erosion model. Future research should focus on the impact of effective particle size on Dc to ensure a full understanding of soil erosion processes.

Coupling of Hofmeister effect, electrolyte concentration, and mechanical composition in soil loss: Runoff simulation study

Electrostatic repulsive forces among soil particles control the intensity of soil loss in runoff and are controlled by the coupling of cation surface reactions (e.g., the Hofmeister effect), electrolyte concentration, and soil particle size composition. In this study, we used different concentrations of Li+, K+, and Cs+ to adjust the cation surface reaction or Hofmeister effect and electrolyte concentration of a neutral purple soil (Entisol). The mechanical composition of the soil was adjusted by adding 0.55–1 mm diameter quartz particles, and the mean surface potential of the soil particles was used to indirectly express the electrostatic repulsive force between particles. The results show that the Hofmeister effect, electrolyte concentration, and mechanical composition are strongly coupled during soil loss, of which the Hofmeister effect plays the most critical role. The physical mechanisms of the coupling effects can be summarized as follows. The electrostatic repulsive force among soil particles depends on the coupling of the Hofmeister effect and electrolyte concentration. Breaking intensity of the soil aggregate, which influences soil loss intensity in runoff, is determined by the electrostatic repulsive force and the production rate of the electrostatic repulsive force-which is controlled by the soil mechanical composition. We conclude that: (1) soil cation surface reactions are a key factor for determining the electrostatic repulsive forces and thus soil loss intensity in runoff; (2) for a given soil, the mechanical composition provides the basic factors that determine the production rate of the electrostatic repulsive force to break soil aggregates; and (3) increasing the soil’s large particle content enhances soil loss intensity but not necessarily soil loss quantity.

Relationship among water penetration, soil structure and understory vegetation according to the land conditions around the greenway in Kohoku New Town

In the slope forest of suburban area, which is affected by the land development, rainwater is getting to be more difficult to be penetrated because of the long-term compaction of surface soil. In the slopes along the greenway in Kohoku New Town, we selected survey plots according to the land conditions and the existence of understory vegetation cover, comparing original slopes of tablelands, slopes of constructed fill and cut mud slopes. We investigated rainwater penetration capacity, soil softness, soil particle size composition, and cover and biomass of understory vegetation, and analyzed their relationships. As a result, soil softness and the hierarchical diversity of understory vegetation had positive correlation with water penetration capacity, and these relationships were found in the cut mud slopes, same as in the original slopes, although no such relation was confirmed in the filled slopes. In the filled slopes, the effect of the underground structure to water penetration is stronger than that of surface soil, but in the cut mud slopes, hierarchical vegetation and softened surface soil are distributed with higher water penetration capacity. It was suggested that it is important to utilize such cut mud slopes to recover rainwater penetration capacity, with conserving the developing vegetation, in the restructuring of the greenway.

A laboratory study to disentangle hydrological, mechanical and structural mechanisms of soil stabilization by plant mucilage between eroding and depositional zones of a slope

AbstractBiological exudates, such as plant mucilage, can greatly stabilize soils, but as the mechanical and hydrological drivers depend much on soil particle size composition, eroding and depositional areas of a slope may respond differently. Soils from an eroded midslope and a depositional footslope in an arable farm were amended with chia (Salvia hispanica) seed mucilage at concentrations of 0 g C kg−1, 0.46 g C kg−1 and 2.3 g C kg−1 mucilage, formed into cores, and then imparted with wetting and drying (WD) cycles. Mucilage increased the stability of these inherently stable soils from 80% to &gt;98% water‐stable macroaggregates at 0 WD cycles regardless of slope position. Aggregate stability was maintained after 5 WD cycles by mucilage, whereas the stability of unamended soil dropped by 66.7% in the footslope and 30.1% in the midslope compared with 0 WD. The underlying physical stability properties were measured by tensile strength and penetration resistance for mechanical properties, water sorptivity and repellency for hydrological properties, and micro‐, meso‐, macro‐ and total porosity for structural properties. Almost every soil physical property measured changed less with WD cycles if mucilage was present. Compared to unamended soil, 2.3 g C kg−1 mucilage amendment decreased water sorptivity from 0.289 mm s−1/2 to 0.122 mm s−1/2 in the midslope and 0.230 mm s−1/2 to 0.182 mm s−1/2 in the footslope after 5 WD cycles. Aggregate stability, total porosity and water sorptivity were correlated. In the midslope, hydrology and penetration resistance were affected the most, which was likely to be driven by mucilage deposition in the macropores of this more coarsely textured soil. In the footslope, the greater impact of mucilage on tensile strength was likely to be driven by buffering of macroporosity formation by WD cycles in this finer‐textured soil.Highlights We explored how slope position interacts with plant mucilage to drive soil physical stability. Changes in soil physical stability by plant mucilage have rarely been considered with slope position. Interactions between mucilage and soil particles caused greater physical stability in the midslope than footslope. Mucilage stabilized soil by easing changes in pore structure, DOC redistribution and water repellency, with particle bonding less important.

The Physical and Chemical Properties of Soil Crust in Straw Checkerboards with Different Ages in the Mu Us Sandland, Northern China

Straw checkerboards, as a mechanical sand barrier, are one of the most important engineering measures for sand control and vegetation restoration. In this study, we characterized the physical and chemical properties of soil crust treated with straw checkerboard in the Mu Us Sandland, Northern China, and investigated the mechanism of sand stabilization and revegetation in the arid area. We collected soil crust from 1.0 × 1.0 m straw checkerboards after revegetation intermittently over 10 years, and then measured properties such as soil particle size composition, bulk density, soil nutrients, pH, and other indicators in the laboratory. During the progress of straw checkerboard treatment, the results showed a significant decrease in percentage of soil crusts sand and a corresponding increase in the portion of silt and clay with straw checkerboard treatment years. The age of straw checkerboard treatment was positively correlated with soil nutrients, such as organic matter, total N, total P, total K, available N, available P, and available K. While pH showed a slightly rising trend, electrical conductivity (EC) was negatively correlated with crust life. The number of plant species has significantly changed, herbaceous vegetation succession being replaced by shrubs over 10 years, and vegetation coverage peaked at the sixth year. This study can represent a successful example of restoration in arid desert regions, thereby supplying more theoretical basis for sand fixation and dessert restoration.

荒漠草原区土壤粒径组成对柠条根际土壤微生物数量及酶活性的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 荒漠草原区土壤粒径组成对柠条根际土壤微生物数量及酶活性的影响 DOI: 10.5846/stxb201810252309 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 宁夏自然科学基金项目（NZ15001）；国家自然科学基金项目（31860158） Effects of soil particle size on enzyme activities and the amount of soil microorganism in rhizosphere of Caragana korshinskii in desert steppe Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:柠条（Caragana korshinskii）是荒漠草原区主要的造林绿化树种，研究其根际土壤微生物和酶活性与不同土壤类型土壤粒径组成的关系有重要意义，然而土壤粒径对荒漠草原柠条根际土壤微生物数量和酶活性的影响知之甚少，探讨土壤颗粒组分与微生物数量、土壤酶活性之间的关系，以及土壤颗粒组成对荒漠草原区固沙灌木植物柠条根际土壤微生物数量及酶活性的影响，可为揭示荒漠草原土壤退化及生态修复提供参考。以宁夏荒漠草原区土壤粒径组成差异显著的灰钙土、红黏土、风沙土环境下栽植的柠条为研究对象，研究不同土壤颗粒组成对根际土壤微生物数量及酶活性的相互关系与影响。结果表明：土壤微生物的数量表现为细菌 > 放线菌 > 真菌。根际土壤中的细菌、真菌数量显著高于非根际，且在3种不同类型的土壤中随着细砂粒的增多，真菌和放线菌数量逐渐降低，而细菌数量呈先增大后减小的趋势；根际与非根际土壤的蔗糖酶、碱性磷酸酶及过氧化氢酶活性均呈现出灰钙土 > 红黏土 > 风沙土的趋势，红黏土根际土壤中的脲酶活性显著高于灰钙土与风沙土；除过氧化氢酶外，土壤酶活性表现为根际高于非根际，在3种不同类型的土壤中随着细砂含量的增加，土壤酶活性均呈递减趋势。土壤颗粒组成与微生物数量之间没有明显的相关性，而与土壤酶活性之间显著相关，土壤酶活性与黏粒、粉粒呈正相关，与细砂、中砂呈负相关关系，根际土壤中酶活性更高，能够为植物及微生物提供更多的营养。 Abstract:Caragana korshinskii is the main afforestation tree species in desert steppe, it is important to study the relationship between microorganisms and enzymes in rhizosphere soil and soil particle size composition. Soil types affect enzyme activities and the amount of microorganism in rhizosphere soil, soil particle size in different soil types is different, however, little is known about how soil particle size affect on enzyme activities and the amount of soil microorganism in rhizosphere of Caragana korshinskii planted in desert steppe. In this study, soil enzyme activities and the amount of soil microorganism in rhizosphere and non-rhizosphere soil in three soil types were analyzed, as well as soil particle size of sierozem, red clay soils, and aeolian sandy soils in Yanchi country of Ningxia. The results showed that the amount of bacteria in rhizosphere soil was significantly higher than that in non-rhizosphere soil, and the amount of fungi increased with the increase of fine sand grains in three soil types. The activities of sucrase, alkaline phosphatase, and catalase in rhizosphere and non-rhizosphere soil presented the tendency of sierozem > red clay soils > aeolian sand soils. The urease activity in red clay soils of rhizosphere was significantly higher than that in sierozem and aeolian sand soils. The amount of fungi and actinomycetes decreased gradually, while the amount of bacteria increased firstly and then decreased. The amount of bacteria and fungi were more abundant than bulk soil. With the increasing of fine sand content, the amount of fungi and actinomycetes gradually decreased while the amount of bacteria increased and then decreased. Soil enzyme activity in rhizosphere exceeded bulk except catalase. With the increasing of fine sand content, soil enzyme activity gradually decreased. There was no significant correlation between soil particle size and the amount of soil microorganism and soil enzyme activity presented a positive correlation with clay and silt sand but it negatively correlated with fine sand and medium sand, rhizosphere soil has higher enzyme activity and could provide more nutrients for plants and microorganisms. 参考文献 相似文献 引证文献

Soil Particle Size Composition and Differences of Different Grassland Types in the Southern Slope of Qilian Mountain

In this paper, we collected soil samples of different grassland types in the southern slope of Qilian Mountain in Qinghai province and analyzed the soil particle size composition and differences. The research result shows that: The soil particle size composition of different grassland types is obviously different, and the soil texture is in silt-sandy soil level. The soil texture from fine to coarse of each grassland is: temperate steppe> alpine meadow> alpine steppe> degenerated grassland> swamp meadow; the overall coefficient of variation(CV) of soil particle size content in different grassland types shows a large difference, the variation of soil silt content in each grassland type was small, while the content of soil sand and clay content fluctuate greatly; the variation degree of soil sand content in each grassland type is moderately variable, but the content of silt and clay is moderately weak, the change rule is sand> clay> silt.

Comparative research on soil magnetic susceptibility and Chroma and grain of grassland soil and farmland soil in alpine region

This thesis aims at researching unchanged perennial farmland and grassland soil on the northern of Qinghai Lake basin and differences between soil magnetic susceptibility, chroma and soil particle size composition of grassland and farmland in lengthways profile(0-60cm). The result shows that the distinction of Xlf between grassland and farmland is smaller above 15cm, and farmland Xlf is finer than grassland below 15cm. The Xfd of grassland is finer than farmland above 30cm, which has a little difference below 30cm. Farmland chroma value is finer than the grassland generally. The lightness of grassland has increased trend and farmland has the decrease trend above 30cm, the lightness of grassland and farmland has no other changes below 30cm, the change of redness and yellowness in lengthways profile has a decrease trend from 0 to 60cm; the clay and silt content of grassland are finer than farmland except sand content; the sand maximum content of farmland in 0-10cm segment; 20 to 35 cm segment sand content decrease and began to increase from 35-60cm segment; the soil particle size composition has a big difference, in particular, when it is above 30cm, it has a little difference below 30cm.

Soil nutrient loss due to tuber crop harvesting and its environmental impact in the North China Plain

Soil loss due to crop harvesting (SLCH) is a soil erosion process that significantly contributes to soil degradation in croplands. However, little is known about soil nutrient losses caused by SLCH and its environmental impacts. In the North China Plain area, we measured the losses of soil organic carbon (SOC) and nitrogen as well as phosphorus due to SLCH and assessed their relationship with soil particle size composition, agronomic practices and soil moisture content. Our results show that the losses by harvesting potato of SOC, total nitrogen (TN), available nitrogen (AN), available phosphorus (AP) and total phosphorus (TP) were 1.7, 1.8, 1.8, 15.9 and 14.1 times compared by harvesting sweet potato, respectively. The variation of SOC, N and P loss by SLCH are mainly explained by the variation of plant density (PD) (17–50%), net mass of an individual tuber (Mcrop/p) (16–74%), soil clay content (34–70%) and water content (19–46%). Taking into account the current sewage treatment system and the ratio of the nutrients adhering to the tubers during transportation from the field (NTRP/SP), the loss of TN and TP by harvesting of potato and sweet potato in the North China Plain area amounts to 3% N and 20% P loads in the water bodies of this region. The fate of the exported N and P in the sewage treatment system ultimately controls the contribution of N and P to the pollution of lakes and rivers. Our results suggest that a large amount of SLCH-induced soil nutrient export during transportation from the field is a potential pollutant source for agricultural water for vast planting areas of tuber crops in China, and should not be overlooked.

Analysis of irradiance losses on a soiled photovoltaic panel using contours

This paper introduces an irradiance loss factor that quantifies the relationship between irradiance, tilt angle and power output of a soiled panel with the soil particle size composition. Artificial soiling experiments were performed using four soil samples at irradiance levels between 200 and 1200W/m2 at 18 tilt angles. Biharmonic interpolation was used to develop power contours in terms of irradiance and tilt angle from experimentally obtained data. These contours were compared with ideal ones of a clean panel to observe deviation in the nature of contours for a soiled panel. A correction factor in terms of particle size composition (as a coefficient to tilt angle) was proposed to calculate power output of a tilted soiled panel. The angular loss on a panel with soil sample containing 150μm particle size in abundance was observed to be 22% and for sample containing 75μm particles in majority, the loss is 24%. Presence of 300μm particle size in abundance causes a 23.7% loss, while 52% angular loss was observed for soil with highest composition of less than 75μm particle size.

Characterization of power losses of a soiled PV panel in Shekhawati region of India

This paper introduces a model that quantifies the relationship between power output, incident irradiance and soil particle size composition of soiled photovoltaic panels. Soil samples used in artificial soiling experiments were collected from Shekhawati region in India and their relative percentage of standard particle sizes is determined from sieve analysis. A non-linear relationship between irradiance and power is obtained using regression analysis showing the effect of particle size composition present on the panel. Further, the tilt angle for maximum power extraction is determined for each soiled panel and the deviation from the optimum tilt angle of a clean panel is observed. It is concluded that, when the soil present on the panel is rich in the particles with diameter (75μm and below), the deviation from the tilt angle of a clean panel is 4°, however if the soil contains higher composition of both 150μm and 300μm particle sizes the deviation is 8°.

Effects of Different Land-Use Types on Soil Erosion Under Natural Rainfall in the Loess Plateau, China

The Loess Plateau, which is located in the arid and semi-arid areas of China, experiences significant soil erosion due to intense human activities and soil erodibility. It is necessary to explore and identify the land-use types or land-use patterns that can control soil erosion and achieve certain agricultural production capabilities. This study established runoff plots with two slope gradients (5° and 15°) in north of Yan'an, one area of the Loess Plateau, with 3 single land-use types (cultivated land, CL; switchgrass, SG; and abandoned land, AL) and 2 composite land-use types (CL-SG and CL-AL). From 2006 to 2012, we continuously monitored the rainfall characteristics, runoff depth, soil loss, vegetation coverage, and soil physical properties. The results indicated a general trend in the number of runoff and soil loss events for the 5 land-use types: CL = CL-SG > CL-AL > SG> AL. The general trend for runoff depth, soil loss, their magnitudes of variation, and the slopes of rainfall-runoff regression equation was CL > CL-SG > CL-AL > SG > AL, whereas the rainfall threshold for runoff generation exhibited the opposite trend. Results of nonparametric test regarding runoff depth/EI30 and soil loss/EI30, where EI30 is the product of rainfall kinetic energy and the maximum rainfall intensity over 30 min, and the runoff depth-soil loss relationship regression indicated that the effect of CL-AL was similar to that of SG; SG was similar to AL; and CL-AL, SG, and AL were superior to CL with regard to soil and water conservation. Runoff depth and soil loss significantly increased as the slope gradient increased. Runoff depth and soil loss were significantly correlated with the soil particle size composition and bulk density, respectively. The strongest significant correlations were found between runoff depth and vegetation coverage as well as between soil loss and vegetation coverage, which showed that vegetation coverage was the primary factor controlling soil erosion. Therefore, the composite land-use type CL-AL and the artificial grassland (SG) are appropriate options because both soil conservation and a certain degree of agricultural production are necessary in the study area.