Vegetative Filter Research Articles

Effects of ionic strength, particle size, flow rate, and vegetation type on colloid transport through a dense vegetation saturated soil system: Experiments and modeling

Summary Colloids are widely distributed in agricultural runoff, especially from croplands with manure applications. Dense vegetation has been suggested to be effective to reduce surface runoff contaminants, including colloidal particles. In this work, small scale laboratory experiments were used to determine the influence of physical and chemical factors (i.e. solution ionic strength, particle size, surface flow rate, and vegetation type) on the surface transport and removal of colloids in a dense vegetation system without drainage. Conservative tracer studies of bromide were conducted as a control to quantify the deposition of colloids onto grass surfaces and the mass exchange of colloids between the overland flow and soil underneath under various experimental conditions. The deposition of colloids enhanced with increases in solution ionic strength and particle size, and with decreases in flow rate. We also found vegetation type played an important role on colloid transport with more deposition onto Ryegrass than onto Bahia grass under the same experimental conditions. A mathematical model combining overland flow, convection–dispersion equations and exchange layer theory was developed to simulate the transport of colloids in overland flow through the dense vegetation. Simulations of the model fitted the experimental data well and helped to understand the effect of ionic strength, particle size, flow rate, and vegetation type on colloid transport and removal in dense vegetation. Although additional investigations are still needed, findings from this study can inform the installation and maintenance of dense vegetation systems, such as vegetative filter strips, to reduce the loading of colloids in surface runoff.

Automatic segmentation of road overpasses and detection of mortar efflorescence using mobile LiDAR data

Abstract This manuscript presents a novel method to automatize the efflorescence detection process in road overpasses using the geometric and radiometric informations from mobile LiDAR data. The study is performed over three main groups of algorithms. First, a data reduction algorithm based on the point cloud normalization, radial and vegetation filters is implemented. A second group of segmentation and classification algorithms uses the incidence angle derived by the LiDAR sensors to separate overpasses from pavement data. Finally, an algorithm to classify efflorescence considering its reflectivity lower than the surrounding granite is developed. The experimental results demonstrate the effectiveness of the method, using field data from the New Bridge of Ourense (Spain).

Integration of bioenergy systems into UK agriculture–New options for management of nitrogen flows

The large flow of reactive nitrogen (N) through agriculture causes negative environmental impacts, pointing to a need for changes in agricultural practices. At the same time, agriculture is expected to provide biomass to support the increasing demand from the UK bioenergy sector. A high-level aggregated model of the agricultural system in the UK was developed, which maintains the existing level of food and livestock production and at the same time increases N recirculation. Integrating three different bioenergy sub-systems into the agricultural system was an essential component of the model development. Cellulosic bioenergy crops were located in the landscape as vegetation filters to intercept and capture N and thereby reduce N leaching. Efficient collection and digestion of manure produced organic N fertiliser and biogas. Efficient forage production for cattle allowed further cultivation of bioenergy plants. Five implementation scenarios were developed to clarify the contribution of these bioenergy sub-systems to improved N management. The results point to a significant potential for improving the productive use of reactive N and for decreasing N losses to water and air. The interception and recirculation of N presently leaching from arable fields is assessed as the most important option. It is also important to increase recirculation of N in manure and in bioenergy system by-flows. Besides mitigating the environmental impacts of agriculture these measures reduce the requirements for newly synthesised N fertilisers. A systems perspective on N, agriculture, and bioenergy systems facilitates N recirculation and promotes effective N use, reducing the need for additional N inputs.

Sediment Trapping from Hyperconcentrated Flow as Affected by Grass Filter Strips

To evaluate the effect of vegetative filter strips on sediment trapping, the spatial distribution of deposited sediment, and the size distribution of deposited particles from hyperconcentrated flows, a simulated grass filter strip experiment was conducted with plastic grass using an adjustable slope steel flume. The simulated vegetation cover was 36%, and the inflow sediment concentrations applied were 147, 238, 320, and 429 kg m−3. The sediment concentration in the outflow, and the sediment particle size were determined. The results showed that the grass filter strips trapped most of the sediment from inflow at low sediment concentration. The deposition efficiency decreased with increasing sediment concentration, being 55.2% and 15.7% in the 147 and 429 kg m−3 sediment treatments, respectively. Most of the deposited sediments were distributed in the upper flume. In addition, the grass filter strips mainly trapped the coarse sediment (particle size > 10 μm).

The performance of grass filter strips in controlling high‐concentration suspended sediment from overland flow under rainfall/non‐rainfall conditions

ABSTRACTThere is little information on the performance of vegetative filter strips (VFS) in filtering high‐concentration sediment from subcritical overland flow. Flume experiments on simulated grass strips were conducted using combinations of three slope gradients (3°, 9° and 15°), five 1‐m‐wide slope positions (from upslope to downslope), two flow rates (60 and 20 L min‐1 m‐1) and sediment concentrations of 100–300 kg m‐3 under simulated rainfall and non‐rainfall conditions. The results showed that sediment deposition efficiency increased with VFS width as a power function. Rainfall significantly reduced sediment deposited within VFS. Higher sediment concentration corresponded to a larger sediment deposition load but reduced deposition efficiency. Flow rate had a negative effect on deposition efficiency but no effect on deposition load. Sediments were more easily deposited at the upper slope position than downslope, and the upper slope position had a higher percentage of coarse sediments. The deposited sediment had significantly greater median diameters (D50) than the inflow sediment. A greater proportion of coarse sediments larger than 25 µm in diameter were deposited, and particles smaller than 1 µm and of 10–25 µm had a better deposition performance than particles of 1–10 µm. Rainfall reduced the deposited sediment D50 at a slope gradient of 3° and had no significant influence on it at 9° or 15°. A higher sediment concentration led to a smaller D50 of the deposited sediment. Rainfall had no significant effect on overland flow velocity. Both the deposited sediment load and D50 decreased with increasing flow velocity, and flow velocity was the most sensitive factor impacting sediment deposition. The results from this study should be useful to control sediment flowing into rivers in areas with serious soil erosion. Copyright © 2013 John Wiley & Sons, Ltd.

Performance Evaluation of Three Vegetative Filter Strip Designs for Controlling Feedlot Runoff Pollution

A vegetative filter strip (VFS) is designed to reduce transport of sediments and nutrients downstream mainly through settling, infiltration (into soil profile), adsorption (to soil and plant materials), and by plant uptake. However, the performance of a VFS greatly depends on a VFS design and climatic conditions of a region. In this paper, relative performance of three VFSs (hereafter Cass County-CC, Sargent County-SC, and Richland County-RC buffers) was evaluated and compared in the context of VFS design for feedlot runoff pollution control and management under agro-climatic condition of North Dakota. Buffer at CC feedlot was established with broadleaf or common cattail (Typha latifolia) grass filter, SC feedlot buffer had Garrison creeping foxtail (Alopecurus arundinaceus Poir.) and reed canary grass (Phalaris arundinaceus), and RC feedlot buffer had mixed grasses. Automatic samplers were installed to collect runoff samples at each inflow and outflow locations. Collected runoff samples were analyzed for total suspended solids (TSS), ortho-phosphorus (ortho-P), total phosphorus (TP), ammonium nitrogen (NH4-N), nitrate nitrogen (NO3-N), total Kjeldahl nitrogen (TKN), total nitrogen (TN), and potassium (K). Cass County (CC) VFS with cattails grass filter had the longest runoff-flow length (65 m) and resulted in better conducive environment for restricted TSS and TP transports reduction and better adsorption of ortho-P, NH4-N, and K compared to SC and RC feedlot buffers. Overall TSS, ortho-P, TP, NH4-N, and K removal efficacies were 88%, 90%, 89%, 91% , and 90%, respectively, at CC VFS. At SC feedlot VFS resulted in the highest NO3-N reduction. Relatively poor performance was observed for the RC feedlot which was due to smaller runoff-flow length (12 m). Overall, CC feedlot outperformed the SC and RC VFSs in respect of TSS, ortho-P, TP, NH4-N, TKN/TN transport reductions.

Antibiotic Effects on Microbial Community Characteristics in Soils under Conservation Management Practices

Veterinary antibiotics (VAs) administered to livestock are introduced to agroecosystems via land application of manure, posing a potential human and environmental health risk. Recent evidence suggests that agroforestry and grass vegetative filter strips (VFS) may act to mitigate VA transport or enhance VA degradation; however, VAs may adversely affect soil microbial communities within VFS and thus alter the primary functioning of the VFS. The objectives of this research were to investigate potential changes in microbial community structure and function and to quantify the development of antibiotic resistance in VFS and no‐till soils exposed to various VA classes and concentrations. Laboratory mesocosms were established using soils collected from no‐till cropland and two VFS (grass and agroforestry). Soils were treated with oxytetracycline or lincomycin (5–200 mg kg−1 soil). Individual mesocosms underwent destructive sampling at nine time points during 63 d, and the soils were tested for soil microbial function (C‐utilization, dehydrogenase, and fluorescein diacetate hydrolysis assays), community structure (phospholipid fatty acid analysis), and antibiotic resistance. Functional assays associated with all VA treatments showed an initial inhibitory effect, but this trend was generally reversed by the seventh day. Shifts in microbial community structure and increased antibiotic resistance were not observed, suggesting that the soil microbial communities were robust to the effects of oxytetracycline and lincomycin at test concentrations. This work indicates that using VFS to mitigate VA loss from agroecosystems will not diminish important primary functions associated with VFS use in agriculture.

Relationships Among Water Stable Aggregates and Organic Matter Fractions Under Conservation Management

Soil organic carbon (SOC) plays an important role in soil aggregation, yet the exact nature of this relationship is not well understood. The objectives of this study were to (i) evaluate relationships among field‐moist and air‐dried macroaggregate stability (WSAFM and WSAAD, respectively), cold water‐extractable organic C from whole soil and the particulate, adsorbed and occluded (PAO) fraction, and associated soil properties, (ii) compare properties of the PAO fraction to those of whole soil, and (iii) evaluate the effects of conservation management practices, including grass vegetative filter strips (VFS), agroforestry VFS, and no‐till, plus landscape positions on these variables. Soil samples were collected in 2007 from an agroecosystem established on claypan soils located in Missouri. This study found that cold water‐extractable organic C and aggregate‐associated organic C were more highly correlated with WSAAD (r ≥ 0.74) than SOC, suggesting that these organic C fractions may play an important role in aggregate stability. In addition, less degraded water‐extractable organic C (as indicated by a greater C/N ratio) was preferentially concentrated in the PAO fraction (C/N = 10.6) relative to whole soil (C/N = 4.2). Further, macroaggregation and accumulation of less degraded organic C (in solid and water‐extracts) was enhanced under grass VFS and agroforestry VFS relative to no‐till. Overall, this study found that macroaggregate stability, cold water‐extractable organic C, and the PAO fraction served as effective early indicators of soil C change in the soil studied.

Extracellular Enzyme Activity in a Willow Sewage Treatment System

This paper presents the results of studies on the activity of extra-cellular enzymes in soil-willow vegetation filter soil which is used in the post-treatment of household sewage in an onsite wastewater treatment system located in central Poland. Wastewater is discharged from the detached house by gravity into the onsite wastewater treatment system. It flows through a connecting pipe into a single-chamber septic tank and is directed by the connecting pipe to a control well to be further channelled in the soil-willow filter by means of a subsurface leaching system. Soil samples for the studies were collected from two depths of 5 cm and 1 m from three plots: close to the wastewater inflow, at mid-length of the plot and close to its terminal part. Soil samples were collected from May to October 2009. The activity of the extra-cellular enzymes was assayed by the fluorometric method using 4-methylumbelliferyl and 7-amido-4-methylcoumarin substrate. The ranking of potential activity of the assayed enzymes was the same at 5 cm and 1 m soil depths, i.e. esterase > phosphmomoesterase > leucine-aminopeptidase > β-glucosidase > α-glucosidase. The highest values of enzymatic activity were recorded in the surface layer of the soil at the wastewater inflow and decreased with increasing distance from that point.

Microbial community diversity in agroforestry and grass vegetative filter strips

Vegetative filter strips (VFS) have long been promoted as a soil conservation practice that yields many additional environmental benefits. Most previous studies have focused primarily on the role of vegetation and/or soil physical properties in these ecosystem services. Few studies have investigated the soil microbial community of VFS. Therefore, we examined potential differences in soil microbial community characteristics of claypan soil planted to VFS with differing vegetation and a traditional row-crop system in a maize–soybean rotation. Samples were tested for soil microbial function and community structure using dehydrogenase and fluorescein diacetate (FDA) hydrolysis enzyme assays and phospholipid fatty acid (PLFA) analysis, respectively. The grass VFS soil exhibited the greatest dehydrogenase activity levels and FDA activity was greater in the grass and agroforestry (i.e., tree–grass) VFS soils relative to the cropland soil. The PLFA analysis revealed community structural differences underlying these functional differences. The agroforestry VFS soil was characterized by a greater proportion of total bacteria, gram-negative bacteria, anaerobic bacteria and mycorrhizal fungi than the cropland soil. The grass VFS soil shared some characteristics with the cropland soils; but the grass VFS supported greater mycorrhizal fungi and protozoa populations. This work highlights differences in soil microbial function and community structure in VFS relative to cropland soil 12 years post VFS establishment. It also enhances our fundamental knowledge regarding soil microorganisms in VFS, which may aid in explaining some ecosystem services provided by VFS (e.g., decomposition of organic agrichemicals).

Distinct influence of filter strips on acute and chronic pesticide aquatic environmental exposure assessments across U.S. EPA scenarios

Vegetative filter strips (VFS) are proposed for protection of receiving water bodies and aquatic organisms from pesticides in runoff, but there is debate regarding the efficiency and filter size requirements. This debate is largely due to the belief that no quantitative methodology exists for predicting runoff buffer efficiency when conducting acute and/or chronic environmental exposure assessments. Previous research has proposed a modeling approach that links the U.S. Environmental Protection Agency’s (EPA’s) PRZM/EXAMS with a well-tested process-based model for VFS (VFSMOD). In this research, we apply the modeling framework to determine (1) the most important input factors for quantifying mass reductions of pesticides by VFS in aquatic exposure assessments relative to three distinct U.S. EPA scenarios encompassing a wide range of conditions; (2) the expected range in percent reductions in acute and chronic estimated environmental concentrations (EECs); and (3) the differential influence of VFS when conducting acute versus chronic exposure assessments. This research utilized three, 30-yr U.S. EPA scenarios: Illinois corn, California tomato, and Oregon wheat. A global sensitivity analysis (GSA) method identified the most important input factors based on discrete uniform probability distributions for five input factors: VFS length (VL), organic-carbon sorption coefficient (Koc), half-lives in both water and soil phases, and application timing. For percent reductions in acute and chronic EECs, VL and application timing were consistently the most important input factors independent of EPA scenario. The potential ranges in acute and chronic EECs varied as a function of EPA scenario and application timing. Reductions in acute EECs were typically less than percent reductions in chronic EECs because acute exposure was driven primarily by large individual rainfall and runon events. Importantly, generic specification of VFS design characteristics equal across scenarios should be avoided. The revised pesticide assessment modeling framework offers the ability to elucidate the complex and non-linear relationships that can inform targeted VFS design specifications.

Evaluation of the Langmuir model in the Soil and Water Assessment Tool for a high soil phosphorus condition

Phosphorus adsorption by a water treatment residual was tested through Langmuir and linear sorption isotherms and applied in the Soil and Water Assessment Tool (SWAT). This study uses laboratory and greenhouse experimental Phosphorus data to evaluate the performance of a modified version of SWAT for high P concentration simulation development. A combination of vegetative filter strips (VFS) and water treatment residuals (WTR) were used to reduce soluble P runoff concentration. To effectively simulate the concentration measured in the experiments, a Langmuir model was incorporated into SWAT. The effective depth of surface runoff and soil interaction over a small subwatershed (0.07 km2) was based on an experimentally determined WTR rate of 64 Mg ha−1. A continuous flow method for rapid measurement of soil hydraulic properties was used to determine soil water contents and hydraulic conductivities. A parameter sensitivity analysis to model output indicated that the Soil Conservation Service runoff curve number for moisture soil condition II was the most responsive to change for this subwatershed. The SWAT model yielded significantly different soluble P and P leached amounts once the Langmuir model was included as an option to the linear P sorption model. With this new adaptation, SWAT was able to simulate higher P concentrations as validated by laboratory and greenhouse experimental data. The laboratory and greenhouse assessment of the WTR provided insight into the data required to evaluate the incorporation of the Langmuir model into a watershed scale tool. The choice of P model simulation (between the Freundlich option already in SWAT and the Langmuir method) was included in a sensitivity analysis performed to define the model sensitivity to selected parameters. This study provides one case of higher P conditions that SWAT was able to more adequately simulate with the Langmuir model incorporated.

Influence of inflow rate of runoff on purification effectiveness of vegetative filter strip

Influence of inflow rate of runoff on purification effectiveness of vegetative filter strip

Effect of vegetative filter strips on herbicide runoff under various types of rainfall

Narrow vegetative filter strips proved to effectively reduce herbicide runoff from cultivated fields mainly due to the ability of vegetation to delay surface runoff, promote infiltration and adsorb herbicides. A field trial was conducted from 2007 to 2009 in north-east Italy in order to evaluate the effectiveness of various types of vegetative filter strips to reduce spring-summer runoff of the herbicides mesotrione, metolachlor and terbuthylazine, widely used in maize, and to evaluate the effect of the rainfall characteristics on the runoff volume and concentration. Results show that without vegetative filter strip the herbicide load that reaches the surface water is about 5–6gha−1year−1 for metolachlor and terbuthylazine (i.e. 0.5–0.9% of the applied rate), confirming that runoff from flat fields as in the Po Valley can have a minor effect on the water quality, and that most of the risk is posed by a few, or even just one extreme rainfall event with a return period of about 25–27years, causing runoff with a maximum concentration of 64–77μgL−1. Mesotrione instead showed rapid soil disappearance and was observed at a concentration of 1.0–3.8μgL−1 only after one extreme (artificial) rainfall. Vegetative filter strips of any type are generally effective and can reduce herbicide runoff by 80–88%. Their effectiveness is steady even under severe rainfall conditions, and this supports their implementation in an environmental regulatory scheme at a catchment or regional scale.

Temporal evolution of atrazine and metolachlor concentrations exported in runoff and subsurface water with vegetated filter strips

Metolachlor and atrazine are herbicides used in corn agriculture and detected in surface- and groundwater. Vegetated filters reduce masses of herbicides in runoff, but less attention has been given to their impact on degradation products and subsurface infiltrated water. The objective was to study the temporal evolution of dissolved metolachlor, atrazine and deethylatrazine concentrations in runoff and subsurface infiltrated water with two types of vegetated filters over 2 years for the first three rains following herbicide application. Runoff and subsurface infiltrated at 90-cm water samples from 12 plots of 30 × 5 m in a completely randomized block design of four replicates of three treatments-control without filter, 5-m-long grass filter, 5-m-long grass and tree filter were analysed using gas chromatography/mass spectrometry. Controls in runoff generally had the highest average atrazine, as high as 739 μg L−1, and metolachlor average concentrations, as high as 1,725 μg L−1. The first rain after application was mainly responsible for atrazine and metolachlor exports. Vegetated filters reduced concentrations of atrazine and metolachlor in runoff below their respective Canadian criterion of 1.8 μg L−1 for atrazine and 7.8 μg L−1 for metolachlor (provisory) (CCME 2002) for the protection of aquatic life when rain did not occur shortly after application. With the need to increase food production and agricultural yields to sustain the increasing world population came the need to develop efficient mitigation tools such as vegetated filter strips to reduce the ecotoxicologial impacts of pesticides. The present study is among the few that examined herbicide degradation products and subsurface infiltrated water under filter strips in order to provide new knowledge on the relationship between herbicide loss pathways and the environmental benefits of these strips. Such knowledge will provide much needed information to modellers, decision makers, ecotoxicologists and agronomists involved in the regulation, design and implementation of vegetated filter strips for the protection of water quality.

Field Application of Farmstead Runoff to Vegetated Filter Strips: Surface and Subsurface Water Quality Assessment

Farmstead runoff poses significant environmental impacts to ground and surface waters. Three vegetated filter strips were assessed for the treatment of dairy farmstead runoff at the soil surface and subsurface at 0.3- or 0. 46-m and 0. 76-m depths for numerous storm events. A medium-sized Michigan dairy was retrofitted with two filter strips on sandy loam soil and a third filter strip was implemented on a small Michigan dairy with sandy soil to collect and treat runoff from feed storage, manure storage, and other impervious farmstead areas. All filter strips were able to eliminate surface runoff via infiltration for all storm events over the duration of the study, eliminating pollutant contributions to surface water. Subsurface effluent was monitored to determine the contributing groundwater concentrations of numerous pollutants including chemical oxygen demand (COD), metals, and nitrates. Subsurface samples have an average reduction of COD concentrations of 20, 11, and 85% for the medium dairy Filter Strip 1 (FS1), medium dairy Filter Strip 2 (FS2), and the small Michigan dairy respectively, resulting in average subsurface concentrations of 355, 3960, and 718 mg L COD. Similar reductions were noted for ammonia and total Kjeldahl nitrogen (TKN) in the subsurface effluent. The small Michigan dairy was able to reduce the pollutant leachate concentrations of COD, TKN, and ammonia over a range of influent concentrations. Increased influent concentrations in the medium Michigan dairy filter strips resulted in an increase in COD, TKN, and ammonia concentrations in the leachate. Manganese was leached from the native soils at all filter strips as evidenced by the increase in manganese concentrations in the leachate. Nitrate concentrations were above standard drinking water limits (10 mg L), averaging subsurface concentrations of 11, 45, and 25 mg L NO-N for FS1, FS2, and the small Michigan dairy, respectively.

Effect of dense vegetation on colloid transport and removal in surface runoff

Widely distributed in aquatic environment, colloids can pose risks to water quality, particularly when loaded in surface runoff, which can facilitate fast distribution of contaminants. It is unclear whether densely vegetated areas, which are known to be effective to reduce solutes and sediment from runoff, can be used to remove colloidal contaminants. In this paper, laboratory experiments were conducted to investigate effects of dense vegetation on colloid transport and removal in surface runoff. First, batch experiments were conducted to obtain the sorption isotherms of colloids (fluorescent microspheres) onto different vegetation parts (grass leaf, stem, and root). Then, a laboratory rainfall/runoff system was used to compare the transport behaviors of a tracer (bromide) and colloids in overland and drainage flows during a simulated rainfall event (64 mm/h). The system was equipped with Bahia grass growing on sandy soil containers with one surface flow and four vertical drainage sampling outlets. We found that all grass parts can sorb aqueous colloids with the Langmuir maximum sorption capacity between 455.3 and 1188.3 mg kg−1. Runoff experimental results demonstrated that both the surface vegetation and the soil (including plant root) underneath can effectively remove colloids from surface and subsurface flows. Only about 33% of the applied colloids were recovered from the outflows, with about 29% and 4% from overland flow and drainages, respectively. Our results suggest that well designed and maintained areas of dense vegetation, like vegetative filter strips, can be used as an effective best management practice to reduce colloidal contaminants in surface runoff.

Rapid determination of 226Ra in environmental samples

A new rapid method for the determination of 226Ra in environmental samples has been developed at the Savannah River Site Environmental Lab (Aiken, SC, USA) that can be used for emergency response or routine sample analyses. The need for rapid analyses in the event of a Radiological Dispersive Device or Improvised Nuclear Device event is well-known. In addition, the recent accident at Fukushima Nuclear Power Plant in March, 2011 reinforces the need to have rapid analyses for radionuclides in environmental samples in the event of a nuclear accident. 226Ra (T1/2 = 1,620 years) is one of the most toxic of the long-lived alpha-emitters present in the environment due to its long life and its tendency to concentrate in bones, which increases the internal radiation dose of individuals. The new method to determine 226Ra in environmental samples utilizes a rapid sodium hydroxide fusion method for solid samples, calcium carbonate precipitation to preconcentrate Ra, and rapid column separation steps to remove interferences. The column separation process uses cation exchange resin to remove large amounts of calcium, Sr Resin to remove barium and Ln Resin as a final purification step to remove 225Ac and potential interferences. The purified 226Ra sample test sources are prepared using barium sulfate microprecipitation in the presence of isopropanol for counting by alpha spectrometry. The method showed good chemical recoveries and effective removal of interferences. The determination of 226Ra in environmental samples can be performed in less than 16 h for vegetation, concrete, brick, soil, and air filter samples with excellent quality for emergency or routine analyses. The sample preparation work takes less than 6 h. 225Ra (T1/2 = 14.9 day) tracer is used and the 225Ra progeny 217At is used to determine chemical yield via alpha spectrometry. The rapid fusion technique is a rugged sample digestion method that ensures that any refractory radium particles are effectively digested. The preconcentration and column separation steps can also be applied to aqueous samples with good results.

Wheat Strip Effects on Nutrient Loads Following Variable Manure Applications

Vegetative filters have been found to significantly reduce nutrient loads in runoff. This study was conducted to: (1) evaluate the effects of a narrow wheat strip, varying manure application rates, and different overland flow rates on runoff nutrient loads following application of beef cattle manure; (2) determine the upper capacity of a narrow wheat strip to reduce nutrient loads by applying excessive amounts of manure; and (3) compare the effectiveness of narrow wheat strips and grass hedges in reducing runoff nutrient loads. A 1.4 m wide strip of actively growing winter wheat was located at the bottom of selected 0.75 m wide by 4.0 m long plots. Three 30 min simulated rainfall events, separated by 24 h intervals, were applied at an intensity of 70 mm h-1 to the plots. The wheat strips were effective in reducing runoff loads of NO3-N, NH4-N, and total nitrogen (TN). Runoff loads of dissolved reactive phosphorus (DP), particulate phosphorus (PP), total phosphorus (TP), NH4-N, and TN were significantly influenced by manure application rate. The application of manure to meet a 2-year rather than a 1-year corn P requirement did not significantly increase DP, PP, or TP loads. However, application of manure to meet a 4-year P requirement resulted in DP, PP, and TP loads that were significantly greater than those obtained for a 2-year P requirement. Runoff rate significantly affected each of the measured water quality parameters. The actively growing wheat strips were much less effective than grass hedges in reducing runoff nutrient loads.

Trapping efficiency with rainfall and seasonal changes in vegetative filter strips over a course of three years

Abstract Nonpoint source pollution does not have a clear route for elimination, and due to the amounts of these types of pollution, it is not easy to eliminate the polluting substances. In addition, the characteristics of nonpoint source pollution can easily be affected by factors other than the concentration, making it difficult to predict the pollution sources. Therefore, we installed a vegetative filter strip, which is a natural type of nonpoint source, around Kyung-An stream and calculated the trapping efficiency occurring during rainfalls, after which we analyzed these results. Over a period of 3 y, we monitored these strips 17 times, dividing the events by growth periods and non-growth periods to look more carefully into their effectiveness according to the rainfall levels. Owing to the special characteristics of nonpoint source pollution, the range of data was wider, but as we went through the elimination process, the number of outflows appeared to be more stable than the number of inflows. During ...