Effect Of Different Soil Types Research Articles

Numerical analysis of pile group, piled raft, and footing using finite element software PLAXIS 2D and GEO5

Foundation plays a vital role in weight transfer from the superstructure to substructure. However, foundation characteristics such as pile group, piled raft, and footing remain unfolded due to their highly non-linear behaviour in different soil types. Bibliography analysis using VOSvierwer algorithm supported the significance of the research. Hence, this study investigates the load-bearing capacity of different types of foundations, including footings, pile groups, and piled rafts, by analyzing experimental data using finite element tools such as PLAXIS 2D and GEO5. The analysis involves examining the impact of various factors such as the influence of surcharge and the effect of different soil types on the load-bearing capabilities of the different types of foundation. For footing, parametric investigations using PLAXIS 2D are conducted to explore deformational changes. Pile groups are analyzed using GEO5 to assess their factor of safety (FOS.) and settling under various criteria, such as pile length and soil type. The study also provides insight into selecting the right type of foundation for civil engineering practice. Findings showed that different soil types have varying deformational behaviours under high loads with sandy soil having less horizontal deformation than clayey soil. Also, it was observed that increasing the pile thickness by 50% resulted in a reduction of 13.88% in settlement and an improvement of 16.66% in the FOS. In conclusion, this study highlights the importance of professionalism, exceptional talent, and outstanding decision-making when assessing the load-bearing capabilities of various foundation types for building structures.

Pengaruh Jenis Tanah terhadap Semai Mahoni Daun Besar (Swietenia Macrophylla)

Big Leaf Mahogany (Swietenia macrophylla) is a tropical plant commonly found growing wild in teak forests and areas near the coast. This plant is also known for its resilience, meaning it can withstand harsh and arid soil conditions. Even without watering for months, mahogany can still survive. The propagation of this plant can be done through seeds, as well as through air layering or grafting. When used for medicinal purposes, it should not be treated with chemical (inorganic) fertilizers or pesticides. The significance of this research lies in providing valuable information to relevant institutions about the suitable soil type for propagating Big Leaf Mahogany (Swietenia macrophylla) seedlings, ensuring high-quality seedlings for reforestation or afforestation efforts. The research was conducted at the Greenhouse of the Faculty of Agriculture from March to June 2023. The objective of this study was to determine the effect of different soil types on the growth of Big Leaf Mahogany (Swietenia macrophylla) seedlings. The experimental design used in this research was a Completely Randomized Design (CRD) with 2 (two) treatments and 3 (three) replications. The treatments consisted of: A (Regosol soil) and A2 (Podsolik soil). The research results indicate that Regosol soil type provided better average growth results for Big Leaf Mahogany (Swietenia macrophylla) seedlings.

Effect of Soil Types on Phenology and Heat Units of Quinoa

Background: Quinoa, a promising pseudocereal crop has superior nutritional profile and able to withstand wide range of biotic and abiotic stresses. Understanding the effect of different soil types on phenology and heat units is important in new crop like quinoa. Therefore, in this investigation, different soil types that widely dispersed around Coimbatore were used to evaluate the performance of quinoa on its phenology and further heat units. Methods: Pot experiment was carried out in the Department of Agronomy, Tamil Nadu Agricultural University, Coimbatore during Kharif 2022 season. Eight soil types were collected from different areas around Coimbatore and tested in completely randomized design with three replications. Development of phonological stages were noted and in turn calculated heat units by using standard formulae. Result: Results of the investigation revealed that clay loam textured Ooty soils took maximum days to attain four phenological stages, viz., branching, panicle initiation, flowering and physiological maturity of quinoa than other soils. Similarly, more heat units (Growing Degree Days, Helio Thermal Units, Photo Thermal Units and Relative Temperature Disparity) were recorded with the soils collected from Ooty when compared to other soils. Sandy loam soils of Mettupalayam registered the least number of days to attain different developmental stages and also recorded the lowest heat units of quinoa. Based on the above results, it can be concluded that among eight different soils, the growth of quinoa was prolonged in clay loam textured Ooty soils and correlation with yield indicated that extending duration enhanced the yield.

Effect of soil types on root infection of Acacia mangium and Eucalyptus pellita by Ganoderma philippii and Pyrrhoderma noxium

Abstract. Indrayadi H, Glen M, Fahrizawati, Siregar BA, Rimbawanto A, Mardai, Tjahjono B, Mohammed C. 2023. Effect of soil types on root infection of Acacia mangium and Eucalyptus pellita by Ganoderma philippii and Pyrrhoderma noxium. Biodiversitas 24: 2358-2364. Acacia mangium Willd. and Eucalyptus pellita F.Muell. are susceptible to red root-rot disease, caused by Ganoderma philippii (Bres. & Henn. ex Sacc.) Bres., has led to the demise of planted A. mangium as a commercial pulpwood in Indonesia. A second root-rot pathogen, Pyrrhoderma noxium (Corner) L.W.Zhou & Y.C.Dai (syn. Phellinus noxius (Corner) G.Cunn.), also attacks both species. The objective of this study was to investigate the effect of different soil types on the root infection of A. mangium and E. pellita by G. philippii and P. noxium. The effect of three contrasting soil types (mineral R41, R51 and peat soil) used in a plantation estate in Riau province on disease development was investigated in a pot trial using four isolates, two of G. philippii and two of P. noxium. Two models of inoculation were used, in one of which inoculated wood blocks were placed against the seedling roots (Model 1), the second where the blocks were 10-20 cm from the roots (Model 2). Fifty weeks after the experiment was established, mortality was significantly higher in the soil of low than high clay content, in A. mangium than E. pellita, and in Model 1 than Model 2; there was no difference between the two G. philippii isolates, and P. noxium did not cause any mortality. G. philippii inoculum could survive in all three soil types for over 9 months; hence, the effect of soil type was not mediated by inoculum longevity. Alternatives should be pursued to limit further development of root-rot diseases in existing E. pellita estates.

Effect of Different Soil Types and Plant Densities on Growth Dynamic and Yield of Sweet Corn (Zea mays L.) in Peninsular Malaysia

Aims: Soils and plant densities are two of the major factors affecting sweet corn growth and yield. Although many worldwide studies were done to evaluate the effect of these factors on sweet corn, it is still necessary to do more study in this area because environmental factors will give significant effect to growth and yield of sweet corn. The objective of this study is to assess yield optimization through different plant densities for different type of soils for sweet corn (Zea mays L.) cultivation.
 Study Design: The experiment was carried out from February to May 2018 using split-split plot design with four replications. Analysis of Variance (ANOVA) with probability value of @ 0.05 using LSD was used to analyze the obtained data. Regression analyses were performed using Nonlinear Regression Model (NLIN Procedure); Logistic Growth Model y=A/(1+be-cx) and their rate of change was calculated using its derivate, dy/dx = (Abce-cx)/(1+be-cx)2.
 Methodology: A variety of sweet corn seed Akik SC422 at (i) four soils which were riverine soil (Tanah Merah, Kelantan), BRIS (Bachok, Kelantan), peat (Simpang Renggam, Johor) and sedentary soil (UPM, Serdang, Selangor) assigned as the main plots with (ii) 1 and 2 row(s) per bed plant arrangements as subplots at (iii) 25 cm and 50 cm planting distances formed as sub-subplots.
 Results: Interaction between peat at 2-row per bed plant arrangement at 25 cm planting distance produced the highest potential plant height while peat at 1-row per bed plant arrangement at 50 cm planting distance the best in highest potential in stem diameter. The interaction between peat with 1-row per bed plant arrangement at 50 cm planting distance; low plant density produced the highest in cob weight, cob length, cob diameter, thousand kernel’s weight and total sugar content. This was reflected by higher growth rates of photosynthesis rate, leaf area per plant and relative chlorophyll content of each individually plant. However, the interaction between peat with 2-row per bed plant arrangement at 25 cm planting distance; high plant density produced the highest in quantity per hectare.
 Conclusion: Results of this study confirms that significant differences in the plant growth, physiological attributes and yield components of sweet corn grown on different soil types, plant arrangements and planting distances.

Crop Productivity, Nutritional and Economic Benefits of No-Till Systems in Smallholder Farms of Ethiopia

Smallholder maize and wheat production systems are characterized by high drudgery. On-farm trials were run for three seasons in Ethiopia. The study assessed the effect of 2 WT direct seeding and growing season on (1) soil quality, and (2) maize and wheat productivity, energy and protein gains, and gross margins, on smallholder farms in Ethiopia. For the wheat crop, the effect of different soil types and agroecological conditions on productivity was assessed. The treatments in paired plots were (i) conventional ploughing practice and (ii) no-till (NT). Soil properties, crop yield, nutrition gains and gross margins were determined. No-till improved soil properties in the short term. No-till produced 1210–1559 kg ha−1 grain, 18–29 GJ ha−1 energy and 121–194 kg ha−1 proteins, and generated 358–385 US$ ha−1 more than the conventional practice in the maize system. In the wheat system, no-till treatment had 341–1107 kg ha−1 grain, 5–16 GJ ha−1 energy and 43–137 kg ha−1 proteins, and generated 230–453 US$ ha−1 more than conventional practice. No-till can be more productive and profitable in the Ethiopian maize and wheat-based cropping systems.

Evaluation of the Performance of a Heat Pipe for Pre-Frozen Soil around a Solar Support by a Numerical Method

The base of solar collector systems is usually installed in soil that contains moisture. In cold regions, due to the low ambient temperature, the moisture in the soil freezes, creating a risk of frost heave. This study analyzed the frost heave mechanism of power transmission and transformation foundation, clarified the factors affecting soil frost heave and the way to solve soil layer frost heave, and proposed the use of heat transfer elements to pre-frozen soil layers to prevent the foundation of the solar collector system from freezing. A numerical model of the ground heat exchange pipes in soil was established. The effects of different soil types, soil moisture content, and the effective radius and operating time on the heat transfer performance of the system were investigated by the verified numerical model. The results show that the heat pipe pre-freezing technology can reduce the drop in soil temperature, thereby increasing the temperature difference between the ground heat exchange pipe and the far-field soil. In terms of the ability to delay the decline in soil temperature, reducing the water content and selecting certain clays can increase the degree and speed of the drop in soil temperature.

Effect of Soil Type on the Nutritional Quality of Groundnut (Arachis hypogaea L) in Burkina Faso

Background: Groundnut is an important food crop in West Africa. It is an oilseed that provides food and nutritional security for many populations. The objective of this study was to determine the effect of different soil types on the nutritional quality of groundnut. Methods: This study was done in the village of Lebda located in the Centre-North region of Burkina Faso. The methodology consisted of collecting groundnut seeds of the SH 470 P variety from fourteen farmers according to three types of soil and determining macronutrient and mineral contents. Result: Analyses of variance showed significant differences between soil types for fat, carbohydrate and iron content. Clay soils showed high fat contents, 46.6%±6.3 g/100 g dry matter. While gravelly soils showed peanut seeds with high carbohydrate contents, 18.8±1.9 g/100 g of dry matter. Iron content varied from 1.9±0.5 mg/100 g dry matter on sandy soils to 2.46±0.39 mg/100 g dry matter on clay soils.

Improved index to quantitatively assess clogging potential based on mixing test results

Clogging frequently occurs during underground excavation using tunnel boring machines (TBMs) and can cause severe schedule delays and cost overruns on projects. However, an index to quantitatively describe clogging potential has not been standardized. This paper presents an improved index to assess clogging potential based on the results of a mixing test. A sensitivity analysis was conducted to understand the effect of different soil types, weight of soil and beater size on the variability of the index. The new index is also compared with the stickiness ratio to show the advantage of using the new index. The results show that although the mass of soil that sticks to the mixing tool varies, assessing clogging potential quantitively using the new index, W/Ac, gives reproducible results, since it reduces the impact of beater size and mass of soil. This paper provides a reliable, straightforward index with improved accuracy to easily assess clogging potential using a simple mixing test that can be conducted in the field.

Effect of the Different Soil Types on Chrysanthemum Cut Flower Quality

Cultivating annual crops in the high upland has the potential to increase avalanche and land erosion. Therefore, chrysanthemum extensification from high upland to medium upland can create sustainable agriculture. The differences between high upland and medium upland are microclimate and soil type. Meanwhile, the effect of soil type between the high upland and the medium upland on the chrysanthemum spray type quality is unknown. The study aimed to determine the effect of different soil types on the quality of chrysanthemums when planted in high upland. The study used a split plot design with two factors. The first factor was the type of soil, such as Andosol from the high upland and Latosol from the medium upland. The second factor was the chrysanthemum varieties, such as Yastayuki (white flower), Arosuka Pelangi (yellow flower) and Socakawani (red flower). The results showed that both Andosol and Latosol soil types could produce the same quality of chrysanthemum in all varieties when planted in high upland. The quality aspects of chrysanthemum were the plant height, the stem diameter, the number of flowers and flower color. Consequently, we could extend the cultivation of chrysanthemum in medium upland by using Latosol type soil.

Bioecology of the guava weevil Conotrachelus psidii Marshall (Coleoptera: Curculionidae)

The guava weevil, Conotrachelus psidii Marshall (Coleoptera: Curculionidae), is a key pest in guava and information concerning the bioecology of this insect is scarce. This work aimed to verify the bioecology of certain aspects of this insect's lifecycle by observations of the period during which the larvae abandon the fruits in order to enter the soil to pupate, the effect of different soil types on penetration times and the subsequent emergence of adults from the soil. Adult population levels were monitored over a two year period and the possible relationship between population density and climatic factors investigated. The abandonment of guava fruits by the larvae was evaluated during two time periods (day-time and night-time). The time taken for 4th instar larvae to penetrate 3 different soil types was observed. The time these insects remained underground and subsequent adult emergence periodicity was evaluated following the release of 4th instar larvae into trays filled with soil. These trays were maintained in the field and observations carried out three times a day (morning, noon, and afternoon). Path analysis was used to investigate the relationship between the climate variables and adult population density. Soil penetration by 4th instar larvae was fastest in clay soils and slowest in sand. There was no difference (p = 0.075) between the number of larvae that abandoned the fruits during the day (51%) and during the night (49%). A majority of the adults emerged from the soil during daytime (86.84%), which was significantly different (p < 0.001) to the number of adults emerging during the night (13.16%). When comparing adult emergence during different periods of the day, the majority emerged in the afternoon (93.94%), with only 6% emerging in the morning (p < 0.001). The average time period between penetration of the soil by 4th instar larvae and adult emergence was approximately nine months (272 days). Adult population density fluctuations were similar during both years studied here, with the lowest population seen from May to August, a peak in November, and then a decline in population density until March. Path analysis showed that rainfall positively influenced C. psidii population density. The results of this work will be important for the development of sustainable IPM programs aiming to control this serious pest of guava orchards.

Experimental study and numerical simulation on dynamic soil‐structure interaction under earthquake excitations

Soil-structure interaction (SSI) phenomena subjected to seismic loadings are investigated in this study. Firstly, shaking table tests on dynamic soil‐structure interaction subjected to seismic loadings are carried out, and SSI effects are analyzed through a comparative study between the soil-structure system and the rigid foundation condition. Then, a corresponding numerical model on the SSI tests is presented. In the finite element model, a bounding surface plasticity model and an equivalent linear method are separately used for simulating the nonlinear behavior of soil. It turns out that the calculated results by the bounding surface plasticity model agree much better with the experimental results. Finally, the effects of different soil types and structural properties on soil-structure interaction are discussed by numerical parametric study. The results show that SSI effects noticeably mitigate the dynamic response of structure, and the closer the frequency of superstructure to the soil frequency, the more obvious the effect of soil-structure interaction. With increased shear wave velocity of soil, the impact of soil-structure interaction weakens. It is important for studying the impact of SSI on structural responses and practical engineering design purposes.

The Effect of Different Soil Types on the Concentration, Distribution, and Trend of Some Micro Nutrients in the Apple Orchards of Urmia Plain

The Effect of Different Soil Types on the Concentration, Distribution, and Trend of Some Micro Nutrients in the Apple Orchards of Urmia Plain

Farklı Dolgu Malzemesine Sahip Donatılı İstinad Duvarlarının Performanslarının Değerlendirilmesi

Failure of retaining walls may cause loss of lives and injuries. Failure of retaining walls also has economical effects because of damaged buildings, infrastructure and vehicles. There have been some devastating cases regarding failure of retaining wall. Therefore, interest for construction of reinforced earth wall has increased in recent years due to several advantages they provide. Reinforced earth wall is more economical than ordinary retaining walls. They are lightweight structure which affects their earthquake performance positively. However, if necessary attention has not paid during design and construction, similar events may occur. Selection of backfill material is also important. In order to build an economical reinforced earth wall, constructors tend to use available soil on site instead of clean sand which changes behavior and performance of the reinforced earth wall significantly. Performance of geosynthetic reinforced earth walls is investigated in this study to find out effects of different soil types used as backfill. Locally available sand and clay is obtained for this purpose. Sand and clay is mixed at different proportions. Amount of clay is increased by 20%. Strength parameters of each mixture are determined by direct shear test. Experimentally computed Mohr-Coulomb material model parameters are used in finite element analysis. Performance of geosynthetic reinforced earth wall is evaluated by considering horizontal deformations, settlement, maximum forces acting on geotextile and its position.

Feasibility of electromagnetic soil heating using magnetic nanoparticle-coated geotextiles

This paper reports a new way of soil heating using a woven and a non-woven geotextile coated with magnetic nanoparticles (MNPs) that generate heat when exposed to a magnetic field. The MNPs were synthesised in the presence of the geotextile, creating and simultaneously coating the MNPs onto the geotextile. The fixation of MNPs on the geotextile was confirmed by direct observation by way of scanning electromagnetic images and an induction heating test. When the prepared geotextile was placed inside a soil medium, heat was generated immediately as the geotextile was exposed to a high-frequency alternating magnetic field, subsequently transferring heat from the MNP-coated geotextile to the surrounding soil. The soil heating performance was greater with the non-woven geotextile than with the woven one, which implies a better capacity to retain the MNPs with a rough surface. However, the effect of different soil types (sand and clay) on heating performance was insignificant. A follow-up study on the heat transfer on a field scale will provide a practical strategy for field application. Overall, the innovative heating method can potentially provide additional functionality to geotextiles as an attractive option for soil heating.

Microwave Transmittance Technique Using Microstrip Patch Antennas, as a Non-Invasive Tool to Determine Soil Moisture in Rhizoboxes.

Investigating the growth behavior of plant root systems as a function of soil water is considered an important information for the study of root physiology. A non-invasive tool based on electromagnetic wave transmittance in the microwave frequency range, operating close to 4.8 GHz, was developed using microstrip patch antennas to determine the volumetric moisture of soil in rhizoboxes. Antennas were placed on both sides of the rhizobox and, using a vector network analyzer, measured the S parameters. The dispersion parameter S21 (dB) was also used to show the effect of different soil types and temperature on the measurement. In addition, system sensitivity, reproducibility and repeatability were evaluated. The quantitative results of the soil moisture, measured in rhizoboxes, presented in this paper, demonstrate that the microwave technique using microstrip patch antennas is a reliable, non-invasive and accurate system, and has shown potentially promising applications for measurement of rhizobox-based root phenotyping.

The Response of CO2 Flux to Soil Warming, Manure Application and Soil Salinity

In this research effect of different soil types (normal and saline), farmyard manure norms (2 ton/ha - 4 ton/ha), manure application techniques (surface and subsurface) and soil temperature levels (20-25°C, 25-30°C, 30-35°C, 35-40°C, 40-45°C and 45-50°C) were examined of the soil CO2 flux on the pots at the laboratory conditions. According to obtained results, soil type (ST), manure norm (MN), manure application technique (MAT) and soil temperature (T) values changed CO2 flux. CO2 flux value of saline soil condition smaller than the normal soil condition. As an expected result, increased the manure amount increased the CO2 flux from soil to atmosphere. However, CO2 flux on the condition that subsurface manure application was less than surface manure application. CO2 flux values at the high soil temperatures were more than low soil temperature conditions. According to the interaction (T*ST, T*MN and T*MAT) results were not statistically significant. Soil CO2 flux were affected by gradually increasing of temperature.

Application of Dempster-Shafer theory and fuzzy analytic hierarchy process for evaluating the effects of geological formation units on groundwater quality.

This study investigates the impacts of different geological units on groundwater quality of an aquifer in southern Iran. The Kriging interpolation technique with a Gaussian semivariogram model was employed to prepare groundwater maps for different water quality constituents. In the next stage, two different models based on fuzzy analytic hierarchy process (AHP) and Dempster-Shafer theory (DST) were used to evaluate the overall water quality index based on the World Health Organization's drinking water standard in different parts of the aquifer. The DST model was able to generate water quality maps with 99.5%, 99%, and 95% confidence levels. The water quality maps were subsequently compared with the geology map of the area to determine the effects of different soil types on the water quality of the aquifer. Both methods showed poor water quality indices in the areas with an Asmari formation containing elevated levels of chloride and sodium ions. Comparison of water quality maps generated by the fuzzy-AHP and DST model revealed that the DST could more reliably handle the uncertainty in the water quality data, and thus was able to generate more accurate water quality maps. Increasing the confidence level in the DST model yielded water quality maps with a decreased overall water quality index. Results of this study could assist water management practices to generate water quality maps for their groundwater resources with confidence levels commensurate socio-economic importance of the region.

不同类型土壤栽培对苦丁茶树叶片生长和光合特性的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 不同类型土壤栽培对苦丁茶树叶片生长和光合特性的影响 DOI: 10.5846/stxb201806111303 作者: 作者单位: 福建农林大学林学院,贵州大学林学院 作者简介: 通讯作者: 中图分类号: 基金项目: 贵州省科技攻关项目（黔科合NY字[2007]3040号） Effects of different soil types on growth and photosynthetic characteristics of Ligustrum robustum Author: Affiliation: College of Forestry,Fujian Agriculture and Forestry University,College of Forestry,Guizhou University 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:研究苦丁茶树叶片生长与光合特性对不同类型土壤栽培的响应特征，确定最适苦丁茶栽培的土壤类型，可为高产优质化的苦丁茶种植业及其规模化生产基地的建立提供科学依据。通过土壤栽培实验研究了不同类型的土壤对苦丁茶树叶片生长、叶片解剖结构、叶绿素含量和光合特性的影响。结果表明：石灰岩土壤栽培条件下，苦丁茶叶长和叶面积比其他6种土壤栽培下的显著提高了34%-57%和43%-68%，叶绿素总量显著增加9%-33%，叶片、上下表皮、海绵组织和栅栏组织的厚度均显著高于其他6种土壤栽培。不同类型土壤栽培下苦丁茶净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）和饱和蒸气压亏缺（Vpdl）的日变化趋势均呈单峰型，日均Pn和Tr值大小依次为：石灰岩 > 石英砂岩 > 玄武岩 > 长石石英砂岩 > 第四纪红色黏土 > 变余砂岩 > 煤系砂页岩，其中石灰岩土壤栽培下的日均Pn值相比其他6种土壤下的显著提高了13%-45%，且叶片最大净光合速率、表观量子效率、暗呼吸速率、光补偿点（LCP）和光饱和点（LSP）也最大，而煤系砂页岩栽培时最低，其LSP和LCP较石灰岩栽培的分别显著下降了40%和46%。综上，在7种类型的土壤中，石灰岩土壤栽培最有利于苦丁茶树叶片的生长发育、并促进叶绿素的合成和加强对光能的吸收利用，最终提高其叶片光合能力，其次为玄武岩土壤，而煤系砂页岩土壤是最不利于苦丁茶树叶片生长发育和光合作用。建议在苦丁茶种植业的发展和规模化生产基地建立时因选择由石灰岩性母岩发育的土壤进行栽培，从而提高苦丁茶的产量和品质。 Abstract:In this study, we investigated the effects of seven types of cultivation soil on leaf growth and photosynthetic characteristics of Ligustrum robustum (kuding tea) seedlings, aiming to provide scientific advices for cultivation and management of the species for cultivation and management of the species. We measured leaf length, width, area, spongy tissue thickness, palisade tissue thickness, layer of palisade tissue, chlorophyll content, and photosynthetic parameters of the seedlings grown in different soil types. The results showed that cultivation in limestone soil increased the length and area of the leaves by 34%-57% and 43%-68%, respectively, when compared with the other six soil types. In addition, leaf thickness, spongy tissue, and palisade tissue were significantly higher, and total chlorophyll content was 9%-33% higher in the limestone soil than in the other six soil types. The soil types did not affect the diurnal variation in net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), and vapor pressure deficit (Vpdl). The daily average of Pn and Tr values in the seven soil types in descending order were as follows:limestone > quartz sandstone > basalt > feldspathic quartz sandstone > quaternary red clay > blastopsammite > coal sand shale. The daily average of Pn value was 13%-45% higher in limestone soil than in the other six soil types. Pn, Gs, and Tr were positively correlated, but they were negatively correlated with Vpdl. The maximum net photosynthetic rate, light saturation (LSP), light compensation (LCP), dark respiration rate, and apparent quantum yield were observed in limestone soil. LSP and LCP were significantly lower in coal sand shale soil (40% and 46%, respectively) than in the limestone soil. In summary, limestone soil is most beneficial for the growth and development of leaves. It can promote the production of chlorophyll and thus enhance the absorption and utilization of light energy and improve leaf growth and photosynthetic capacity. The second appropriate soil type is basalt. In contrast, coal sand shale soil is most unfavorable for the growth and development of leaves and photosynthesis. Therefore, limestone soil should be used for the large-scale plantation of L. robustum and improvement of the yield and quality of kuding tea. 参考文献 相似文献 引证文献

Measuring ephemeral gully erosion rates and topographical thresholds in an urban watershed using unmanned aerial systems and structure from motion photogrammetric techniques.

Both rural and urban development can lead to accelerated gully erosion. Quantifying gully erosion is challenging in environments where gullies are rapidly repaired, and in urban areas where microtopographic complexity complicates the delineation of contributing areas. This study used unmanned aerial vehicles (UAVs) and Structure-from-Motion (SfM) photogrammetric techniques to quantify gully erosion in the Los Laureles Canyon watershed, a rapidly urbanizing watershed in Tijuana, Mexico. Following a storm event, the gully network extent was mapped using an orthomosaic (0.038 m pixel size); the local slope and watershed area contributing to each gully head were mapped with a Digital Surface Model (0.3 m pixel size). Gullies formed almost exclusively on unpaved roads which had erodible soils and concentrated flow. Management practices (e.g. road maintenance that fill gullies after large storms) contributed to total sediment production at the watershed scale. Sediment production from gully erosion was higher and threshold values of slope and drainage area for gully incision were lower than ephemeral gullies reported for agricultural settings. This indicates high vulnerability of unpaved roads to gully erosion which is consistent with high soil erodibility and low critical shear stress measured in the laboratory with a mini jet-erosion-test device. Future studies that evaluate effects of different soil types on gully erosion rates for unpaved roads, as well as those that model effects of management practices such as road paving and their impact on runoff, soil erosion, and sediment loads are needed to advance sediment management and planning in urban watersheds.