Performance of geosynthetic cementitious composite mat and vetiver on soil erosion control

An understanding of how different land covers affect soil erosion caused by rainfall is necessary in mountainous areas.The land cover usually plays an important role in controlling landslide hazards associated with these terrains.This paper presents the results of a field experiment where several types of land covers were placed on a full-scale embankment as erosion control.An 8 m wide,21 m long,and 3 m high embankment with a 45°side-slope was built with lateric soil.The soil was compacted under a relative compaction of 70%to simulate a natural soil slope.Two sides of the embankment were divided into six land cover areas,with three different areas of bare soil,and one each of a geosynthetic cementitious composite mat(GCCM),vetiver grass,and a combination of GCCM and vegetation.Soil erosion and moisture levels were monitored for each land cover area during six natural rainfall events encountered over the experimental period.Field results were compared with a numerical simulation and empirical soil loss equation.The results revealed that the GCCM gave the best erosion control immediately after installation,but vetiver grass also exhibited good erosion control six months postconstruction.

Effects of Multiple Soil Conditioners on a Mine Site Acid Sulfate Soil for Vetiver Growth

A pot experiment was conducted to investigate the effects of various soil treatments on the growth of vetiver grass ( Vetiveria zizanioides (L.) Nash) with the objective of formulating appropriate soil media for use in sulfide-bearing mined areas. An acidic mine site acid sulfate soil (pH 2.8) was treated with different soil conditioner formula including hydrated lime, red mud (bauxite residues), zeolitic rock powder, biosolids and a compound fertilizer. Soils treated with red mud and hydrated lime corrected soil acidity and reduced or eliminated metal toxicity enabling the establishment of vetiver grass.Although over-liming affected growth, some seedlings of vetiver survived the initial strong alkaline conditions. Addition of appropriate amounts of zeolitic rock powder also enhanced growth, but over-application caused detrimental effects. In this experiment, soil medium with the best growth performance of vetiver was 50 g of red mud, 10 g of lime, 30 g of zeolitic rock powder and 30 g of biosolids with 2000 g of mine soils (100% survival rate with the greatest biomass and number of new shoots), but adding a chemical fertilizer to this media adversely impacted plant growth. In addition, a high application rate of biosolids resulted in poorer growth of vetiver, compared to a moderate application rate.

Electrophysiological responses of the rice striped stem borer Chilo suppressalis to volatiles of the trap plant vetiver grass (Vetiveria zizanioides L.)

Vetiver grass （Vetiveria zizanioides L.） was previously found to effectively attract female adults of Chilo suppressalis （Walker）, an important pest of rice. To determine the volatile compounds involved in this attraction, electroantennography （EAG） responses to seven synthetic volatiles released from vetiver plants were examined. Our results indicated that the responses of C. suppressalis adult antennae to the different compounds varied widely. The compounds elicited strong EAG responses in female antennae were subsequently selected for further EAG response tests, namely, caryophyllene, β-ocimene, linalool and a-pinene. EAG responses to a combination of these four compounds did not differ significantly from the individual compounds. However, pair combination tests indicated that 0.01μg μL-1linalool and 50 μg μL-1 α-pinene, 50 μgμL-1 caryophyllene and 0.01μg μL-1 linalool, 0.01 μg μL-1 13-ocimene and 0.01 μg μL-1 linalool, and 0.01μg μL-1 β-ocimene and 50 μg μL-1 caryophyllene elicited significantly greater EAG responses in 3-day female moths compared to the 1-day female. These compound combinations and the corresponding ratios are probably playing an important role in attracting female adults of C. suppressalis to the vetiver grass.

Application of vetiver grass Vetiveria zizanioides: Poaceae(L.) as a trap plant for rice stem borer Chilo suppressalis: Crambidae(Walker) in the paddy fields

Rice is an important staple food in China and it is at risk of attack by rice striped stem borer Chilo suppressalis, which occurs in most rice growing areas. In recent years, severe C. suppressalis outbreaks have been observed in China mainly due to changes in the rice cultivation systems, wide adoption of hybrid varieties and resistance to the dominant insecticides. Management relies primarily on chemical insecticides and resistance is an important contributing factor in these outbreaks. As a result, food safety of agricultural produce is reduced and the ecological and environmental integrities are threatened as well. Recently, environmentally friendly pest management measures, such as trap plants have been introduced for C. suppressalis management and this method can greatly reduce insecticide use. Our previous results indicated that the vetiver grass(Vetiveria zizanioides) is a dead-end trap plant that can effectively attract the adult females of C. suppressalis to lay eggs on it but where larvae are unable to complete their life cycle. This paper further explored the application of vetiver grass as a trap plant to manage C. suppressalis in the paddy fields. This environment-friendly tool can not only reduce C. suppressalis populations, it can also increase the diversity and abundance of natural enemies that can provide better environmental conditions for rice production.

Quantifying Tillage and Vetiver Grass (Vetiveria nigritana Stapf) Strips Spacing Effects on Runoff, Soil Loss and Maize Yield in Southern Guinea Savanna of Nigeria

Soil erosion induced by inappropriate tillage remains a serious problem on many agricultural fields in the humid tropics. Studies were conducted between 2004 and 2006, on an Alfisol in Ogbomoso in the Southern Guinea Savanna of Nigeria to evaluate the effectiveness of Vetiver Grass(Vetiveria nigritana) Strips(VGS) under different tillage systems. The experiment was split-plot laid out in a randomized complete block design with two replications on 6% slope with 18 runoff plots. Main plot treatments were tillage systems; Manual Clearing(MC), Ploughing(P) and Ploughing plus Harrowing(PH). Subplot treatments were VGS spaced at intervals of 5 m(eight strips) and 10 m(four strips) with the control(no-vetiver). Runoffs and soil losses were collected after each major storm. Chemical analyses of eroded sediments and runoff were determined. Data were analyzed using ANOVA at p<0.05. The results showed that tillage had no significant reduction in runoffs and soil losses, but they were reduced with MC compared with P and PH. Mean total runoff on 5 and 10 m VGS plots were significantly(p<0.05) lower than that of the control by 74.4% and 45.0%, respectively. Corresponding soils loss on 5 and 10 m VGS plots were 27.1% and 53.5%, respectively. Mean NO3-N levels in runoff water were lower under PH plots than those under MC plots by 79.0% and 66.5%, respectively in 2004 and 2006 growing seasons. VGS spaced at 5 m significantly(p<0.05) reduced NO3-N loss than the control by 108.8% in 2004. Nutrients loads of eroded sediments were consistently higher for the control(no-vetiver) plots and least for 5 m VGS plot. Carbon, nitrogen and phosphorus contents of eroded sediments were 90%-92.4%, 83%-83.6% and 97%-97.8%, respectively, and were lower on 5 m than other treatments. Maize grain yield was significantly(p<0.05) affected by both tillage and VGS spacing only in 2005 growing season. P plot produced higher grain yield than MC and PH by 79.9% and 99.1%, respectively. Also, grain yield on VGS plot was significantly(p<0.05) higher on 5 and 10 m VGS plots than the control by 82.2% and 85.4%, respectively. The significant beneficial effect of PH in producing higher yields was dwarfed by the potential danger of soil erosion in the absence of a soil erosion control measure. The results showed that a balance needed to be struck between mechanical clearance and protective measure against soil erosion.

Effects of Vetiveria zizanioides Planting on Water Quality in Areas Surrounding Coal Gangue Mountain

In order to investigate the correlation between the variations in the environmental water quality indexes and the distance of water bodies from the planting region of vetiver, samples of surface water were gathered from the water bodies surrounding an abandoned coal gangue mountain of Dahead coal mine (Dahe, Liupanshui, Guizhou Province) based on the method of field survey and typical analysis. According to the results, the planting of vetiver could effectively purify the water bodies surrounding the coal gangue mountain. Detailed findings include three aspects:(1) The main pollutants detected in water bodies around the coal gangue mountain were SO4 2-, NO3 -, Fe and Cu, with a concentration of 869.45, 35.16, 26.06, and 40.85 mg/L respectively in wet season and all exceeded the national environmental standards for surface water.(2) The pH values of water bodies 150~200 m away from the vetiver planting region stayed within the limits of national environmental standards for surface water and presented a homogeneous feature, revealing that vetiver has the capacity to adjust the pH of the surrounding water body.(3) The contents of Fe, Mn, Cu, SO4 2-, and NO3 - under all treatments, tended to increase with the increasing distance of water bodies from the vetiver planting region;it means the shorter the distance between the water body and the vetiver planting region is, the higher the adsorption rate and purification effects will be;the optimal concentrations of Fe, Mn, and Cu were 0 mg/L, much lower than the national environmental standards for surface water.

Seedling Production from Seeds of a Wild Ecotype of Vetiver Grass (<i>Vetiveria zizanioides</i>L.) in Southern China

Vetiver grass (Vetiveria zizanioides L.) is widely used for soil and water conservation, and land management. In practice, all vetiver seedlings are propagated via ramets or tillers, which cannot meet the market demand and would also destroy the original habitat. Most vetiver genotypes flower but do not produce seeds. A wild ecotype of vetiver grass originated in southern China is fertile, but the rate of seed germination is very low. This study aimed to develop a novel method to improve its seed germination and seedling establishment. In the field, the inflorescences of wild vetiver were wrapped using a transparent plastic bag with a pot containing wet soils. The effects of inflorescence bagging and Tween 80 application on seed germination and seedling growth were examined. The results showed that seed development was characterized by low seed setting rate (19.2%), uneven maturity time, easy shedding (more than 95% of spikelets shed off 20 days after flowering), therefore difficult harvest of viable seeds. Bagging the inflorescence with moist soils in pot ensured the mature seeds falling onto the nursery soil surface and absorbing water for germination while the immature seeds continued to grow on the inflorescence. Bigging not only improved seed development and maturity, saved the procedure of seed collection and storage, but also provided a humid micro-environment for seed germination and seedling growth. Tween 80 as a surfactant promoted seed water absorption, germination and seedling growth. This simple and novel method has integrated the procedures of seed collection, storage, germination and seedling establishment, and enables the production of a large number of healthy seedlings. The possible reasons for the degeneration and disappearance of the original population were also discussed from the perspective of the disadvantages of vetiver propagation.

Phytoremediation Potential of Vetiver Grass (Vetiveria Zizanioides) in Two Mixed Heavy Metal Contaminated Soils from the Zoundweogo and Boulkiemde Regions of Burkina Faso (West Africa)

In the agricultural regions of Burkina Faso, urban solid waste fertilizers were usually applied. This activity is likely to contaminate the soils and expose populations to serious diseases. This study aims to assess rate of heavy metal (Cd, Cu, Mn, Pb, Zn, Ni, Cr) contamination in both agricultural lixisol and vertisol and to evaluate the removal efficiency of heavy metals using Vetiver grass on different two mixed heavy metal contaminated soils. A pot experiment was conducted to compare the metal accumulation and overall efficiency of metal uptake by different plant parts (roots and shoots) on both tropical soils. After 3 and 6 months growing on laboratory conditions, Vetiver grass plants were harvested and heavy metal concentrations in shoot and root parts determined by Inductively Coupled Plasma - Atomic Emission Spectroscopy. The results indicate that at 3 and 6 moths, the shoot and root concentrations of heavy metals in Vetiver grass harvested in lixisol were higher than vertisol. For different plant parts, all metal concentrations were higher in root than in shoot, except Cu and Pb. At the 3 and 6 months, the BCF values > 1 for Cd, Cu and Zn in both soils showed Vetiver grass as an effective phyto-stabilizer for these metals. However, the TF values > 1 for Cd (lixisol), Mn, Zn Ni and Cr (vertisol) indicated the efficiency of Vetiver for phytoextraction. The results of this study showed that Vetiver is more effective in lixisol, but it can be used for remediation of both studied tropical soils from agricultural region of Burkina Faso. Nevertheless, considering the special limitations of the experimental conditions, further field monitoring is necessary to demonstrate the phytoremediation efficiency of Vetiver in agricultural soils under the climatic conditions of Burkina Faso.

Using Vetiver grass technology for mitigating sediment loads in the Talakhaya Watershed areas in Rota, CNMI

Talakhaya watershed in Rota is identified as a Coral Reef Management Priority site for CNMI (Com-monwealth of Northern Mariana Islands). In 2010 federal and jurisdictional partners developed a Con-servation Action Plan (CAP) for the Talakhaya Watershed. The goal of this initial Watershed Soil Loss Assessment therefore, was to assist in evaluating the re-vegetation objectives of 'Mitigating Sediment Load' in the Talakhaya watershed by making a thorough characterization of its main river systems. The objectives of this project were to reach those goals by measuring the hydrological parameters following the installation and the use of water meters, barometric level loggers, turbidity meters and rain gauges. The water flow as well as the turbidity level of each stream leading to the ocean from the Talakhaya Watershed was measured and sedimentation level was assessed accordingly. The results from the monitoring of the watershed conducted during the project timeline reported here show that all four rivers under study have statistically different stage-discharge curves. The river's relationship between time and turbidity also vary especially in the summer months of the first-year observations. Linear and convex polynomial relationships were sometimes observed in the different rainfall groupings for the four river systems, however relationships were often not significant. This-being-said, Quantile Regressions suggest that when data from all four river systems are combined for cases where there is some de-tectable rainfall, a maximum possible turbidity level can be defined.

Influence of root suction on tensile strength of Chrysopogon zizanioides roots and its implication on bioslope stabilization

Root tensile strength is an important factor controlling the performance of bio-slope stabilization works. Due to evapotranspiration and climate factors, the root moisture content and its suction can vary seasonally in practice and may not equal soil suction. The influences of suction and root moisture contents were investigated on Chrysopogon zizanioides(vetiver grass) root tensile strength. The root specimens were equilibrated with moist air in different suction conditions(0, 10, 20, and 50 kPa), prior to root tension tests. The root-water characteristic curve or relationship between root moisture and suction, was determined. The increase in suction resulted in decreased tensile strengths of the grass roots, particularly those with diameter of about 0.2 mm, which constituted 50.7% of all roots. For 1 mm roots, the tensile strength appeared to be unaffected by suction increase. The average root tensile strengths were used to estimate the root cohesion in slope stability analysis to find variation of safety factors of a bioengineered slope in different suction conditions. The analysis showed that the critical condition of slope with the lowest factor of safety would happen when the soil suction was zero and the root suction was high. Such condition may occur during a heavy rain period after a prolonged drought.

Defluoridation of water using biosorbents

Contamination of drinking water due to fluoride is a severe health hazard problem. Excess of fluoride (>1.5 mg/l) in drinking water is harmful to human health. Various treatment technologies for removing fluoride from groundwater have been investigated. The present study showed that Vetiveria zizanioides, a herbal plant of Kerala—commonly known as Vetiver is an effective adsorbent for the removal of fluoride from aqueous solution. Phosphoric acid activated Vetiver root showed good adsorption capacity than the fresh powdered Vetiver root. Batch sorptive defluoridation was conducted under variable experimental conditions such as pH, agitation time, dose of adsorbent and particle size. Maximum defluoridation was achieved at pH 6;there is a greater possibility of columbic interaction between fluoride ion and adsorbent surface at this pH. The percentage of fluoride removal in- creases with adsorbent dose and time at a given initial solute concentration. The surface and sorption characteristics were analyzed using SEM techniques. Freundlich as well as Langmuir isotherm were plotted and kinetic constants were determined.

Green remediation of tetracyclines in soil-water systems

The presence of tetracyclines in soil and surface water is an emerging concern. The present study was undertaken to investigate remediation of tetracylines (tetracycline (TC), oxytetracycline (OTC) and chlortetracycline (CTC)) from aqueous solution using vetiver grass, water lettuce, and sunflower and root exudates of water lettuce, sunflower and from soil by tomato, Indian mustard and carrot plant. The data of this study denote that vetiver grass, water lettuce, sunflower remedy tetracyclines from water. The remediation % after 63 days of treatment was 87-61 for TC;88-68 for OTC and 87-68 for CTC. The remediation of tetracyclines at lower concentration of antibiotics in presence of root exudates of water lettuce and sunflower was more than 99% and remediation was faster than water lettuce or sunflower. The remediation of tetracyclines from aqueous solution may be due to oxidation of-OH group(s) of tetracycline through a process that is thought to involve reactive oxygen intermediates and/or role of peroxidase enzyme. The plant crops viz., tomato, Indian mustard and carrot can remedy 41%-72% of amended tetracyclines. The maximum bioaccumulation of TC and CTC was in Indian mustard and OTC was maximally bioaccumulated in tomato.

Effect of Soil and Water Conservation Measures on Selected Soil Physical and Chemical Properties and Barley （Hordeum spp.） Yield

A study was conducted in 2007/2008 at Absela locality, Banja Shikudad District of the Amhara National Regional State, Ethiopia to evaluate the effects of soil bunds stabilized with vetiver grass （IT. zizanioides） and tree lucerne （C. palmensis） on soil physical and chemical properties, bund height, inter-terrace slope and barley （Hordeum vulgare L.） yield. Data were analyzed using one-way analysis of variance （ANOVA） and mean values for the treatments were separated using Duncan＇s Multiple Range Test. Results indicated that the non-conserved fields had significantly （p 〈 0.05） lower organic carbon and was found to contain 66% less OM from the average of the conserved treatment. 9-year old sole soil bund, the 9-year old soil bund stabilized with tree lucerne, the 9-year old soil bund stabilized with vetiver, and the 6-year old soil bund stabilized with tree lucerne had 71.20, 68.56, 52.30, and 36.12%, respectively higher percent OM than the control treatment. The trend was similar for total nitrogen. The non-conserved treatment had a higher bulk density when compared to the conserved fields. Fields with soil bunds stabilized with vetiver grass had the highest bund height and the lowest inter-terrace slope than fields treated with the rest of remaining conservation measures. Barley grain yields were significantly （P 〈 0.05） greater in both the soil accumulation and loss zones of the conserved fields than the non-conserved （control） treatment. Practicing soil conservation measures and curtailing causes of land degradation could improve the soil physical and chemical properties thereby increase land productivity of the conserved land.

A review on dump slope stabilization by revegetation with reference to indigenous plant

The waste,subgrade ROM and fine dumps of iron ore mines are characterized by high rock fragment contents,low moisture retention capacity,higher bulk density,low nutrients,lower pH and elevated metal concentrations.Use of suitable revegetation programme,that require the selection of right type of plants to be used vis-à-vis the site condition and characteristics,can enhance the long-term stability,both mechanical and ecological,of dumps(waste,subgrade ROM and fines)through providing vegetative cover to control soil erosion and gully formation,consolidation of dump top and side surfaces,binding the loose particles through intricate roof system,etc.This paper overviews the roles of revegetation programme that can be used where vegetation is considered to be the long-term answer to slope protection and erosion control.Various revegetation processes like Coir matting,lemon grass,vetiver grass and indigenous plant may find a wide range of usage in iron ore mines for dump stabilization.The Miyawaki method of plantation is more effective than the conventional method of plantation.This will lead to co-existence of plants,and as a matter of fact each plant draws from the other vital nutrients and they grow to become strong and healthy.The Miyawaki plantation technique aims at“survival of the fittest”,and the area which undergone such plantation has an ecology of their own.The indigenous plant has good binding capacity and helps to control soil erosion as well as improve the dump stability.These indigenous plant species include Shorea robusta(Sal),Dalbergia sisoo(Shisham),Karanj and Azadirachta(Neem).The growth of indigenous plants is dependent upon the soil quality as well as the organic matter of the dump material.The leaf debris plays an important role for improving the organic matter of the dump material to successfully implement the revegetation programme.

Characteristics of unsaturated soil slope covered with capillary barrier system and deep-rooted grass under different rainfall patterns Check for updates

Rainfall-induced slope failures commonly occur in residual soil slopes.Slope failures are triggered by the reduction in soil strength.This is attributed to the decrease in soil suction due to rainwater infiltration.Slope covers like capillary barrier system and vegetative cover are effective methods that can be used to prevent rainfall-induced slope failures.The capillary barrier system is able to limit the rainwater infiltration,and vegetation can contribute to the increase in soil strength.Vetiver grass is widely planted in tropical and subtropical areas of the world for soil and water conservation.This study investigates the characteristics of unsaturated soil slope covered with capillary barrier system and Vetiver grass in comparison with the original slope through numerical analyses and field measurements.The analyses were carried out under the advanced,normal,and delayed rainfall patterns.The results of the analyses indicated that the capillary barrier system played a more significant role than the Vetiver grass in maintaining slope stability,although both the capillary barrier system and Vetiver grass contributed to the slope stability.In addition,both numerical analyses and field measurements showed that under the delayed and normal rainfall patterns,when antecedent rainwater infiltration could increase the soil moisture,the capillary barrier system performed much better compared to Vetiver grass in maintaining soil matric suctions and slope stability.