Mixed Soil Samples Research Articles

Isolation of antibiotics producing bacteria from marine soil and comparative analysis of same with commercially available drugs

The isolation of antibiotic producing bacteria from marine soil and comparative analysis of same with ciprofloxacin and amoxicillin against staphylococcus aureus and Escherichia coli was carried out in a Microbiology Laboratory of Chukwuemeka Odumegwu Ojukwu University, Uli. This was done to isolate antibiotic producing bacteria and compare same with existing commercially available antibiotics with a view to using marine soil in the treatment of common bacterial infections. Soil samples were collected from Bonny Island Sea, Port Harcourt. One gram of mixed soil sample was serially diluted and spread-plated on nutrient agar plates. The representative isolates obtained were sub-cultured to get a pure culture. Morphological, biochemical, physiological characteristics of the bacteria were analyzed. Agar well diffusion was carried out. One isolate had a substantial antibacterial activity with 3.5mm zone of inhibition against two test bacteria used in the preliminary screening. The isolate was marked as Streptomyces (STR I) and was identified as Streptomyces griseus while other isolates did not show any antibacterial activity. Ciprofloxacin showed the highest antibacterial activity to both Staphylococcus aureus and Escherichia coli of 3.7mm and 4.0mm respectively while Amoxicillin showed antibacterial activity of 3.5mm and 2.7mm respectively. This reveals that antibiotic producing bacteria from marine soil are also effective in antimicrobial activity and could be used for antimicrobial chemotherapy.

Rapid determination of mixed soil and biochar properties using a shortwave near infrared spectroscopy approach

Presented study aimed to apply the near infrared spectroscopy approach in determining some related properties of soil mixed by biochars. Spectra data of soil samples were acquired using a self-developed NIRS instrument (PSD NIRS i16) in shortwave near infrared (SW-NIRS) range from 1000 to 1750 nm with optical gain 4x and co-added of 32 scans per acquisitions. Spectra data were corrected and enhanced using mean centering and peak normalization. Multivariate analysis namely principal component regression (PCR) were employed to develop NIRS based models followed with leverage validation. The results showed that mixed soil samples with biochar properties (K and N) can be determined simultaneously with maximum correlation coefficient are 0.86 and 0.77 for K and N respectively. Based on this obtained performance, it may conclude that SW-NIRS approach can be applied to determine related properties of mixed soil biochar samples rapidly.

Effects of ageing on the occurrence form of uranium in vertical soil layers near an uranium tailing reservoir

Uranium contamination due to mining and metallurgical operations is a serious problem worldwide. Upon entering an ecosystem, uranium poses a high potential threat to humans and other organisms. A better understanding of the distribution and speciation of uranium in contaminated soil is therefore necessary over relevant time scales. In this study, we collected uncontaminated soil samples, including eluvial (E), illuvial (B), and parent-material (C) horizons, from a soil profile near a uranium tailing reservoir in southern China. Four columns were filled with the E, B, and C horizons and three types of mixed soil samples to simulate the behavior of uranium in soil near an uranium tailing reservoir. The atomic-scale mechanisms were investigated using X-ray diffraction, X-ray photoelectron spectroscopy, and other characterization methods. The results show that air, clay minerals, iron and manganese oxides, and other soil properties exert important effects on the forms and mobility of uranium in soil, and that ageing leads to a rearrangement and chemical fractionation of uranium in soil.

Effects of ammonium ion and bentonite content on permeability of bentonite-clay mixture

Sanitary landfill is a common method for the treatment of municipal solid waste. The landfill leachate contains a large amount of NH4+, which will affect the physicochemical properties of bentonite, and subsequently change the anti-seepage function of the bentonite enhanced cutoff wall. The permeability tests were carried out on bentonite-clay mixed soil infiltrated by the ammonium salt solutions using a head pressure control permeameter. The results show that saturated permeability coefficient of the bentonite-clay mixture increases with the decrease of bentonite content and with the increase of NH4+ concentration. Moreover, the reasonable mass content of bentonite is about 10% if the studied bentonite-clay mixture are used in vertical cutoff wall. The scanning electron microscope (SEM) and the nuclear magnetic resonance (NMR) measurements were conducted on the bentonite-clay mixed soil samples with different bentonite contents, and samples infiltrated by the ammonium salt solutions with different concentrations, and afterwards the variations of the micro pore structure and pore-size distribution were obtained. Connecting the Donnan osmotic pressure with saturated permeability of bentonite-clay mixed soils, the effect mechanism of bentonite content and ammonium solution concentration on the permeability of the bentonite-clay mixture was analyzed.

Unified Evaluation of Consolidation Parameters for Low to High Plastic Range of Cohesive Soils

Knowing the engineering properties of geomaterials is imperative to make the right decision while designing and executing any geotechnical project. For the economical and safe geotechnical design, quick characterization of the compressibility properties of the cohesive soil is often desirable; these properties are indeed tedious to determine through actual tests. Therefore, correlating the consolidation parameters of the soils with its index properties has a great significance in the geotechnical engineering field. Several attempts have been made in the past to develop correlations between the consolidation parameters and index properties of the cohesive soils, within certain limitations. However, there is still a need to develop such correlations based on the extensive database, composing of unified plasticity range of soils, i.e., low to high plasticity. In the current study, 148 undisturbed soil specimens were obtained from different areas of Pakistan. Out of which 120 samples were utilized to develop correlations, and 28 samples were used to check the validity of the developed correlations. In order to enhance the index properties database, 30 more bentonite mixed soil samples were prepared and tested accordingly. Correlations to envisage different consolidation parameters such as compression index, compression ratio and coefficient of volume compressibility were developed using 150 cohesive soil samples of low to high plasticity. In addition, the performance of these developed correlations was verified on a set of 40 soil samples and compared with the performance of different correlations available in the literature. The percentage deviation in the prediction of compressibility characteristics through developed correlations in the present study was found to be very less, which endorsed the excellent reliability of the developed correlations.

Organic Contaminant-Triggered Self-Healing Soil Mix Cut-Off Wall Materials Incorporating Oil Sorbents

Soil mix cut-off walls have been increasingly used for containment of organic contaminants in polluted land. However, the mixed soil is susceptible to deterioration due to aggressive environmental and mechanical stresses, leading to crack-originated damage and requiring costly maintenance. This paper proposed a novel approach to achieve self-healing properties of soil mix cut-off wall materials triggered by the ingress of organic contaminants. Oil sorbent polymers with high absorption and swelling capacities were incorporated in a cementitious grout and mixed with soil using a laboratory-scale auger setup. The self-healing performance results showed that 500 µm-wide cracks could be bridged and blocked by the swollen oil sorbents, and that the permeability was reduced by almost an order of magnitude after the permeation of liquid paraffin. It was shown by micro-CT scan tests that the network formed by the swollen oil sorbents acted as attachments and binder, preventing the cracked mixed soil sample from crumbling, and that the oil sorbents swelled three times in volume and therefore occupied the air space and blocked the cracks in the matrix. These promising results exhibit the potential for the oil sorbents to provide soil mix cut-off walls in organically-contaminated land with self-healing properties and enhanced durability.

Effects of chemical solutions on the hydromechanical behavior of a laterite/bentonite mixture used as an engineered barrier

Compacted laterite and bentonite, as well as a mixture of the two, are strongly impermeable and can effectively prevent the migration and diffusion of contaminants. This study explored the feasibility of employing a laterite/bentonite mixture as a vertical barrier in landfills, tailings ponds, or sites contaminated by heavy metals. Permeability tests using chemical solutions of different concentrations and compression tests were performed on mixed bentonite/laterite samples with different dry densities and mixing ratios. The permeability and consolidation characteristics were verified using scanning electron microscopy. The hydraulic conductivity of the laterite samples decreased with increased dry density, and the hydraulic conductivity of the mixed-soil samples decreased with increased bentonite content. Adding bentonite significantly improved seepage control performance. The hydraulic conductivity of the pure laterite was 4.7 × 10−7 cm/s, whereas that of the laterite sample mixed with 20% bentonite was 1.6 × 10−8 cm/s. The compacted laterite with a dry density of 1.5 g/cm3 was demonstrated to satisfy the permeability specifications to serve as a landfill seepage control system. When the concentration of the heavy metal or salt solutions increased, the laterite flocculation increased, and the hydraulic conductivity decreased. The laterite in the mixed soil samples substantially affected these characteristics, particularly decreasing the hydraulic conductivity. As the concentration of the chemical solutions increased, the yield stress of the compacted samples and the compression index decreased, and the compression performance improved. These findings indicate that chemical solutions significantly affect the hydromechanical behavior of a laterite/bentonite mixture used as an engineered barrier.

Effects of long-term super absorbent polymer and organic manure on soil structure and organic carbon distribution in different soil layers

Super absorbent polymer (SAP) and organic manure (OM) may improve soil structure and change soil organic carbon (SOC) composition and agroecosystem functioning. However, the understanding of the effects of SAP and OM on SOC composition, specifically in deeper soil layers, is still not clear. The objectives of this study were to examine the effects of long-term application of SAP and OM (8 years) on changes in SOC and soil structure down to a soil depth of 100 cm. Therefore, in order to investigate the stability of soil structure and the distribution of organic carbon at different soil depths (0-10 cm, 10-20 cm,…, 90-100 cm) under long-term application of SAP, OM, and a control treatment, soil structure and soil organic carbon content were analyzed in mixed soil samples and undisturbed soil samples. The results indicated that with depth, the proportion of large aggregates (0.5-2.0 mm) decreased gradually, while the proportion of small aggregates (<0.25 mm) increased gradually. Compared with the control, SAP treatment was conducive to the increment of>0.5 mm soil aggregates in the 0-30 cm and 40-60 cm soil layers (P < 0.05) and 0.25-0.5 mm in the 0-50 cm soil layer (P < 0.05), and while the OM treatment had the same effect in the 0-30 cm soil layer (P < 0.05). The total organic carbon content (TOC) and labile organic carbon content (LOC) of bulk soil increased (0-20 cm) initially with depth, and then decreased (20-70 cm) approximately. In the 0-50 cm soil layer, the TOC and LOC under SAP treatment were higher than those under OM treatment. The SAP treatment was more beneficial to the increase of the TOC and LOC of 0.5-2.0 mm and 0.25-0.5 mm aggregates in the 10-40 cm soil layer compared with the control and OM treatment (P < 0.05). The SAP treatment was also more beneficial in increasing the contribution rate of organic carbon (CROC) in> 0.5 mm aggregates in 0-40 cm soil depth, while the OM treatment was more beneficial in increasing the CROC of > 0.5 mm aggregates in 0-30 cm soil depth. The SAP treatment improved the stability of the soil structure in 0-30 cm and 40-60 cm depths, and the OM treatment had the same effect in the 0-30 cm depth. Compared with the control and OM treatments, SAP treatment has shown to be the most beneficial in improving soil structure and increasing organic carbon content.

Chromium Removal Using Soil Loaded with Green Iron Nanoparticles.

Chromate is considered as a serious environmental problem due its toxicity. Iron nanoparticles produced by green tea polyphenols (GT-nZVI) is a powerful reductant, which can effectively reduce Cr(VI) to Cr(III). Nano ZVI suspension was initially conceived ideal for direct injection in the contaminated aquifers. However GT-nZVI presents limited mobility in calcareous aquifers. For this reason the incorporation of nanoiron in a permeable reactive barrier was investigated as an alternative mode of GT-nZVI application. Namely an amount of soil was loaded with nZVI (0.40mmol/g of soil) and was evaluated for Cr(VI) removal by conducting batch and column tests. Batch tests were carried out by mixing soil samples, loaded with different levels of nZVI from 0.04 to 0.40mmol per gram, with contaminated groundwater (GW) containing 1300ppb Cr(VI). Cr(VI) concentration dropped below detection limit within 1day using the highest nZVI dose. Soil pre-loaded with nZVI (S-nZVI) presented also high efficiency for chromates remediation, when tested under flow conditions by conducting column tests.

Effect of compaction characteristics on hydraulic conductivity performance for sedimentary residual soil mixed bentonite as compacted liners

This paper discusses on the compaction effect to the hydraulic conductivity performance for the sedimentary residual soil mixed bentonite. This mixture is proposed as a barrier material in landfill area and may possibly potential materials for use as compacted soil liners in landfills for leachate protection. A laboratories series was conducted to evaluate the effectiveness of compaction characteristics on sedimentary residual soil mixed with different percentage of bentonite (5%, 10% and 15%). The sedimentary residual soil sample was used in this study and was collected in sedimentary residual formation area in Salak Tinggi, Malaysia and named as Salak Tinggi soil. The mixed samples were compacted at three different compaction effort with different energy to determine the maximum dry density (MDD) and optimum moisture content (OMC). Then, the permeability test to determine the hydraulic conductivity (k) was conducted at MDD condition at every compaction effort at effective stress of 100 kPa. The results show that the MDD value were slightly low for the entire soil sample mixed with bentonite at all compaction energy level. Instead it shows all the three different compaction efforts applied to the mixed soil samples with bentonite yielded hydraulic conductivity less (k ≤ 1x10−9m/s). In fact, the increment of bentonite content also resulted in lower of MDD value and hydraulic conductivity value. However, MDD values were found to be higher for mixed soil when compacted with high compaction effort. The results of hydraulic conductivity tests demonstrated that hydraulic conductivity, k ≤ 1x10−9m/s can be achieved just by using lower compaction energy for the soil mix with bentonite. Instead it considered as suitable materials for liner due to the hydraulic requirement for soil barrier, k ≤ 1x10−9m/s. This finding show that compaction efforts play an important role for workability of the mixtures and significantly to be used as compacted of soil liner materials.

高寒地区种植不同种类牧草对土壤节肢动物群落的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 高寒地区种植不同种类牧草对土壤节肢动物群落的影响 DOI: 10.5846/stxb201809091931 作者: 作者单位: 西南民族大学生命科学与技术学院,西南民族大学生命科学与技术学院,西南民族大学生命科学与技术学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41371270）；四川省科技厅应用基础研究计划重点项目（2018JY0556）；重点研发项目（2018SZ0333）；四川省教育厅创新团队项目（14TD0049）；西南民族大学研究生创新项目（CX2017SZ076） Effects of different forage species on soil arthropod communities on the Qinghai-Tibetan plateau Author: Affiliation: College of Life Science and Technologies,Southwest Minzu University,College of Life Science and Technologies,Southwest Minzu University,College of Life Science and Technologies,Southwest Minzu 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:为了明确高寒地区种植不同种类牧草对土壤节肢动物群落的影响，于2016年7月，选取2013年建植的垂穗披碱草、老芒麦、早熟禾、羊茅、燕麦、苜蓿6种牧草地为研究样地，以外围天然草地为对照样地，采集0-15 cm混合土样，采用干漏斗法（Tullgren）分离土壤节肢动物。结果表明：（1）7种类型牧草种植地对土壤节肢动物群落组成结构、密度、类群数、Shannon多样性指数和Simpson优势度指数均有显著差异性（P < 0.05或0.01）。群落密度、类群数和Shannon多样性指数均表现为燕麦显著高于垂穗披碱草和苜蓿牧草地，而Simpson指数与之相反，其他几种牧草地间土壤节肢动物群落指数均无显著差异性。（2）典范对应分析（CCA）结果表明，影响土壤节肢动物群落组成结构的主要因素是土壤pH、TN、N/P、C/N、AK；其中，在垂穗披碱草样地中土壤节肢动物群落与pH呈正相关，在早熟禾样地中土壤节肢动物群落与TN和N/P呈正相关，而在天然草地中土壤节肢动物群落与C/N和AK呈正相关。（3）回归分析表明，土壤节肢动物群落密度及多样性指数仅与TK含量呈显著正相关（P < 0.05或0.01）。研究表明，在青藏高原种植不同种类牧草对土壤节肢动物的群落结构、密度和多样性均存在较大的影响。从长远的观点来看，种植苜蓿等其他种类牧草虽然能缓解草畜矛盾，但会降低土壤节肢动物多样性，不利于生物多样性保护和草地生态系统的可持续利用。 Abstract:The objective of this study was to examine the effects of different forage species on soil arthropod communities in alpine ecosystems. Six grasslands dominated by six different forage species, viz., Elymus nutans, Elymus sibiricus, Poa annua, Festuca ovina, Avena sativa, and Medicago sativa, and a natural grassland (NG) were selected for study in July 2016, in Hongyuan county, northwest Sichuan. Two plots measuring 2 m×4 m each were setup in each type of grassland. In the each areas,three sampling points were selected by the diagonal method and mixed soil samples in the 0-15 cm layer were collected. and soil arthropods were extracted from soil samples for 48 h at 38℃ using the Tullgren method in the laboratory. (1)There were significant differences in soil arthropod community density, group number, Shannon diversity index and Simpson dominance index among the seven grasslands (P < 0.05 or 0.01).The community density, group number and Shannon diversity index showed that Avena sativa were significantly higher than Elymus nutans and Medicago sativa, while the Simpson index was opposite. There was no significant difference in soil arthropod community index among other grassland types. Sex.(2) The results of canonical correspondence analysis (CCA) showed that the composition of soil arthropod community was mainly affected by pH, TN, N/P, C/N, and AK, among other parameters; and the soil arthropod community was positively correlated with pH in Elymus nutans,with TN and N/P in P. annua grassland, and with K in natural grassland.(3) The regression analysis between soil arthropod diversity indexshowed that only total K had a significant positive correlation(P < 0.05 or 0.01).The effects of cultivating different forage species on the community structure, abundance, and diversity of soil arthropods varied among the seven grasslands in the Qinghai-Tibet Plateau. Clutivating Medicago sativa and some other forage species will reduce the diversity of soil arthropods,and not benefit biodiversity conservation and the sustainable utilization of grassland ecosystems in the long term,although the contradictions between forage and livestock can be alleviated to some extent.We strongly recommend that a comprehensive ecological assessment should be conducted before planting forage species. 参考文献 相似文献 引证文献

Effect of Reforestation on Microbiological Activity of Postagrogenic Soils in European Russia

We have studied the microbiological activity of postagrogenic soddy–podzolic, gray, and dark gray forest soils representing succession stages of natural reforestation on former agricultural lands in various forest zones. The chosen succession chronoseries of postagrogenic soils are uniform and include arable soil, abandoned lands of various ages, and forest cenoses. The content of organic carbon (Corg) and total nitrogen (N), pH, water holding capacity (WHC), basal respiration (Vbasal), microbial biomass carbon (Cmic), and ecophysiological parameters of the status of microbial communities (metabolic coefficient qCO2; the Cmic: Corg ratio, and specific rate of basal respiration calculated as the Vbasal: Corg ratio) are determined in mixed soil samples taken from 0–10 and 10–20 cm layers. It has been revealed that the transformation of arable soils into abandoned lands constantly occupied by meadow or forest vegetation usually results in the progressive accumulation of organic carbon in the 0–10-cm layer. This causes more active soil respiration and a significant increase in the pool of microbial carbon. Parallel to this, the processes of podzol formation upon the development of forest vegetation result in a pronounced increase in acidity in the 10–20 cm layer, which causes a decrease in Vbasal and Cmic in soils of forest cenosis. For all the studied chronoseries of postagrogenic soils, the correlation between microbiological parameters (Vbasal and Cmic) and the general soil properties (Corg, N, and WHC) is the closest. The following factors (in decreasing order) exert effect on the dynamics of all the studied properties at postagrogenic evolution: forest zone/soil type > age of abandoned land ˜ depth in the arable layer.

HYDROCHLORIC ACID HEAT REACTION METHOD TO MEASURE CEMENT CONTENTS IN CEMENT MIXED SOILS

The mixing cement with soft soil to increase their strength has been used in many constructionsites and it is important that soil and cement are well mixed. In order to evaluate the mixing accuracy duringconstruction, it may be required to measure the cement content by sampling the cement mixed soil. While thereare several methods for measuring cement content, the hydrochloric acid heat reaction (HAHR) method iseasiest and quickest and is relatively high in precision to measure the cement content in fresh concrete.However, to apply HAHR to the fresh soil cement, there were many questions about a test condition. Thisstudy investigated conditions to apply the HAHR method to cement mixed soil. At first, cement are mixed tothe local soil samples in the ratio of 0 to 10g/100g. Initial temperatures (T0) of the mixed soil and hydrochloricacid are measured. 100 g of mixed soil is put in an insulated container. 100mL of hydrochloric acid is added,and reaction temperature (T1) is measured. Relationship of temperature rise (T1-T0) and cement content is acalibration graph. The relation is proportional. And, the temperature rises are measured about 100g of cementmixed soil of the site. Its cement content is obtained using the calibration curve. It is optimal to use 6Mhydrochloric acid for this method. It is necessary to examine it with local soil and local cement to prepare acalibration curve. When the water content ratio of the soil greatly changes, it is necessary for the calibrationcurve to be updated. HAHR tests are done in 10 to 60 minutes after having mixed soil and cement in the caseof samples containing a little water. But, in the case of containing much water, the tests are done under thespecified elapsed time. As an example of the result, the cement content of soil can be determined from therising temperature of the sample soil.

Variation of soil bacterial diversity after the invasion of Phyllostachys edulis into Pinus massoniana forest.

To identify the variation in soil bacterial community diversity brought by the invasion of Phyllostachys edulis into Pinus massoniana forest, we collected mixed soil samples from three types of forests, including a pure Ph. edulis forest, a mixed Ph. edulis and conifers (P. massoniana) fore-st, and a mixed forest of evergreen broadleaves and conifers. Samples were analyzed by high-throughput sequencing for measuring the soil bacterial community diversity and structure. The results showed that the bacterial communities comprised of 511 genera, 160 families, 134 orders, 88 classes, and 39 phyla. The proportion of Acidobateria in the pure Ph. edulis forest was significantly lower and the proportions of Actinobacteria, Bacteroidetes, TM7, and Chlamydiae were significantly higher than that in other forests. Meanwhile, various genera showed significant differences in proportions in both the mixed forests when compared with their corresponding proportions in the pure Ph. edulis forest. There were 130 non-dominant genera presented alone in each of the two mixed forests, at proportions between 0.005% and 0.1%. The pure Ph. edulis forest had the lowest &Agr; diversity, while that of the mixed Ph. edulis and evergreen broadleaf forest was intermediate, and that of the mixed evergreen broadleaf and coniferous forest was the highest. The index of &Agr; diversity followed evergreen coniferous mixed forest > bamboo needle mixed forest > pure bamboo forest, and the diffe-rence between the mixed Ph. edulis and evergreen broadleaf forest and the mixed evergreen broadleaf and coniferous forest was insignificant. The PCoA results revealed that the invasion of Ph. edulis affected the population diversity and community structure of soil bacteria. There was a significant correlation between the percentage of non-dominant bacterial phyla in the soil (less than 0.1% of the proportion) and the soil environmental gradient such as water-soluble organic nitrogen and nitrate. Water-soluble organic nitrogen and nitrate had strong effects on the non-dominant bacterial population in the soil following the invasion of Ph. edulis into the P. massoniana forest. These findings would serve as important references for further related studies.

Study on effect of coarse-grained content on the mechanical properties of frozen mixed soils

In this study, the mechanical behavior of frozen mixed soils was studied by laboratory tests, and the effects of coarse-grained content on their mechanical properties were analyzed in detail. With the increase of coarse-grained content, the strength of frozen mixed soils decreases and then increases slightly. In regard to volume deformation, both the maximum volume expansion and maximum volume contraction of the frozen mixed soils decrease with the increasing confining pressure. All frozen mixed soil samples show strain softening during the shear process. The softening index, IS, defined here to analyze the degree of strain softening, increases as the mass ratio increases when the confining pressure is above 3.0 MPa, in which the mass ratio is defined as the ratio of coarse-grained mass to fine-grained one. The greater the IS, the more obvious of the strain softening. All stress-strain curves of the frozen mixed soils can be divided into three stages: (1) the first stage is the initial linear stage of εa ≤ εi, where the ice strength and deformation are dominant, and the linear limit stress point (σi) corresponding to εi increases with the mass ratio increasing. The axial strain range of the first stage in the experimental results of our test is about 0.874%; (2) the second stage is the hardening stage of εi < εa ≤ ε1f. In a macroscopic view, the samples show shear contraction. With the increases of mass ratio, the axial strain range of the second stage is reduced and the failure strain (ε1f) of the frozen mixed soils also decreases; and (3) the third stage is the softening stage of εa>ε1f. The samples exhibit dilatancy on a macro scale. Finally, the Mohr-Coulomb strength criterion is modified to discuss the strength variation of frozen mixed soils and an expression of stress-strain relationship for the three-stage characteristics of frozen mixed soils is proposed.

Contribution of organic amendments to soil organic matter detected by thermogravimetry

AbstractSustainable soil management requires reliable and accurate monitoring of changes in soil organic matter (SOM). However, despite the development of improved analytical techniques during the last decades, there are still limits in the detection of small changes in soil organic carbon content and SOM composition. This study focused on the detection of such changes under laboratory conditions by adding different organic amendments to soils. The model experiments consisted of artificially mixing soil samples from non‐fertilized plots of three German long‐term agricultural experiments in Bad Lauchstädt (silty loam), Grossbeeren (silty sand), and Müncheberg (loamy sand) with straw, farmyard manure, sheep faeces, and charcoal in quantities from 3 to 180 t ha−1each. In these mixtures we determined the organic carbon contents by elemental analysis and by thermal mass losses (TML) determined by thermogravimetry. The results confirmed the higher reliability of elemental analysis compared to TML for organic carbon content determination. The sensitivity of both methods was not sufficient to detect the changes in organic carbon content caused by small quantities of organic amendments (3 t ha−1or 0.1–0.4 g C kg−1soil). In the case of elemental analysis, the detectability of changes in carbon content increased with quantities of added amendments, but the method could not distinguish different types of organic amendments. On the contrary, the based on analysis of degradation temperatures, the TML allowed this discrimination together with their quantitative analysis. For example, added charcoal was not visible in TML from 320 to 330°C, which is used for carbon content determination. However, increasing quantities of charcoal were reflected in a higher TML around 520°C. Furthermore, differences between measured (with TML110–550) and predicted mass loss on ignition using both organic carbon (with TML330) and clay contents (with TML140) were confirmed as a suitable indicator for detection of organic amendments in different types of soils. We conclude that thermogravimetry enables the sensitive detection of organic fertilizers and organic amendments in soils under arable land use.

Pengaruh Penambahan Abu Ampas Tebu dan Kapur Terhadap Karakteristik Tanah Lempung Ekspansif (Studi Kasus : Tanah di Bojonegoro)

In each region having different types of soil, one type of soil is expansive clay. In Indonesia, more than 1/5 of the land area in Indonesia are an expansive clay. This type of soil will affected by changes in water content and experience significant shrinkage. Therefore, to improve the soil and minimize shrinkage growth, an effort is needed, one of which is soil stabilization. Physical testing of soil with soil samples in the district Ngasem, Kab. Bojonegoro which is expansive clay soil shows that the CBR value is 3.953%, and the swelling value is 6.1858%. With such physical conditions with low carrying capacity it is necessary to stabilize the soil on clay in Bojonegoro. Stabilization efforts carried out are by chemical stabilization by mixing soil samples with additives in the form of bagasse and lime ash. The results of the physical soil test from the preliminary research conducted by the author by mixing bagasse ash in the soil with variations in levels of 8%, 10%, 12%, 14% showed a mixture of 8% bagasse ash was the optimum level for repairs to the soil. So it is used a mixture of 8% bagasse ash with the addition of variations in lime content of 4%, 6% and 8% of the total weight of the mixture. A mixture of 8% bagasse ash and 6% lime content produced a CBR value of 9,324%, this CBR value increased to 135.87%. While the swelling value is 0.1681%, with the same mixture level. This swelling value decreased to 97.28%. For the value of free development it decreased to 217.7% from the previous one which amounted to 70.59% to 22.22%.

Rapid determination of soil organic matter content based on soil colour obtained by a digital camera

ABSTRACTSoil organic matter (SOM) is an important component of soil and a significant criterion in determining the dynamics of soil quality. A rapid, low-cost method to measure SOM content is needed to support the development of precision agriculture. This article studied the quantitative relationship between SOM and soil colour using a digital camera, which is relatively inexpensive and easy to operate, as a portable tool for obtaining colour information of the soil surface. The results show that mixed samples with different soil particle sizes reduce the noise of the image and are more suitable than uniform soil samples for predicting the SOM. Among the three bands of red, green, and blue (RGB), the red band had the best correlation with SOM, and its reciprocal correlation coefficient (r) reached 0.75. The reciprocal regression model of the RGB colour model provided good prediction results for mixed soil samples, with a coefficient of determination (R2) of 0.76 and a root mean square error (RMSE) of 0.55, and the validation result had an excellent predictive ability (R2val = 0.85 and RMSEval = 0.53). The single-variation predictive model of CIELa*b* colour space model through transformation of the RGB colour space model performed well. The model built by colour intensity values had a strong stability and forecasting capacity. Thus, a digital camera can be used as an alternative tool to rapidly measure SOM.

PEMANFAATAN LIMBAH BATUBARA (FLY ASH) UNTUK BAHAN STABILISASI TANAH DASAR KONSTRUKSI JALAN YANG RAMAH LINGKUNGAN

Now days, Indonesia gets much the using of coal as alternative energy because increased of oil price and increased demand in the country. The expected production of coal in 2010 at about 230 million tons, where 68.5 million tons for local needs (45-46 million tons for electric power plant). Sumatera Selatan province is one of coal resources province in Indonesia and also has electric power plant have to promoted the utilizing of polluted material from electricity power plant. Industry electric coal power plant produced 5% polluted as fly ash and bottom ash, where 10-20% as bottom ash and as 80-90% fly ash. That polluted can be utilized as additives material  in soil stabilization for road construction.  This publication proposes an assessment of the utilization of lime, Portland cement (PC), fly ash as stabilizer of soft sub grades material in highway construction. The research conducts various contents of fly ash to different types of clay soils from various sites in Kuantan. The compaction tests and California Bearing Ratio (CBR) tests were applied in soil samples to estimate the optimum mixture design. The samples were set up by mixing soil samples with various content of fly ash and at optimum water content. The accomplishment of sub-grade stabilization depends on the engineering properties of soils and characteristic of additives. The laboratory result shows that the strength gain in stabilization mainly depends on two factors: additives content and molding water content. The variation content of fly ash and were 4%, 8% and 12% by total weight.Keywords: Sustainable, Engineering Properties of Soil, Soil Stabilization, CBR

Spatial Distribution and Source of Perfluorinated Compounds in Urban Soil from Part of Cities in Anhui Province, China

In order to explore the spatial distribution and source of perfluorinated compounds (PFCs),eleven mixed urban soil samples were collected from 7 cities in Anhui Province in 2013.Fifteen individual PFCs were detected by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS),and principal components analysis was used to trace the different sources of PFCs in urban soil.The results showed that the total concentration of PFCs (ΣPFCs) ranged from 1.15 to 5.98 ng·g-1 dry weight (dw),with an average concentration of 2.69 ng·g-1.perfluorooctane sulfonate (PFOS) with a concentration range of n.d.-3.56 ng·g-1 and an average concentration of 0.96 ng·g-1 was the dominant PFC contaminant,followed by perfluorooctane acid (PFOA) with a concentration range of n.d.-2.89 ng·g-1 and an average concentration of 0.64 ng·g-1.The highest ΣPFCs concentration in all selected mixed urban soil samples was from Chuzhou City with the value of 5.89 ng·g-1,followed by Jingxian County of Xuancheng City (4.04 ng·g-1).Interestingly,the PFOS concentration was as high as 3.56 ng·g-1 in Jingxian County,accounting for 88.1% of the total PFCs concentration,which might be influenced by paper industry in this area.Comparing to other soil samples in China,ΣPFCs concentration of urban soil from Anhui Province was at middle level.Over 60% of ΣPFCs in urban soil of Anhui province could be attributed to the four principal components,represented by PFOA,perfluorobutane sulfonate,perfluorododecanoic acid,perfluorobutane acid and PFOS.