Vegetative Filter Strip Design for Grassed Areas Treated with Animal Manures

Vegetative filter strips (VFS) are a low-cost management option that have been demonstrated to be effective in reducing runoff transport of fertilizer constituents applied to grassed areas (pasture or meadow). Runoff quality studies involving fertilizers applied to grassed areas suggest that VFS can be designed by assuming that (1) only infiltration is responsible for pollutant removal, (2) the first post-application runoff event is most important from a water quality perspective (enabling a design event approach), and (3) no pollutant build-up that degrades VFS performance will occur. The purpose of this study was to develop a VFS design algorithm for grassed areas that uses available information on the water quality dynamics of these systems to simplify the design process to the greatest degree practical. The design algorithm consists of the SCS (1972) Curve Number method for runoff estimation and the Overcash et al. (1981) equation for predicting concentrations of pollutants exiting a VFS as a function of VFS and runoff parameters. The procedure can be used to determine the VFS length required to meet either an allowable pollutant runoff concentration or allowable pollutant mass transport. As an alternative, the process can be used to determine VFS length required to achieve given relative reductions in incoming pollutant runoff concentrations and mass transport. This algorithm can be used quickly and with minimal data to determine the VFS length requirement necessary to provide any desired degree of effectiveness given inputs such as incoming pollutant runoff concentration, background pollutant runoff concentration, soil hydrologic properties, and design storm parameters. Charts are presented that eliminate the need for computations in selected cases

Poultry Litter-Treated Length Effects on Quality of Runoff from Fescue Plots

Using experimental data and/or mathematical simulation models to identify practices that reduce pollution from manure-treated areas is sometimes perceived as limited by the unknown validity of extrapolating plot-scale data to larger areas and by uncertainties in modeling transport of various pollutants. The objectives of this study were to assess the effect of length of manure treatment on runoff concentrations of poultry litter constituents and to define the modes of transport (particulate versus soluble) for nitrogen (N), phosphorus (P), carbon (C), and solids. Poultry litter was applied to three 1.5- x 18.3-m fescue (Festuca arundinacea Schreb.) plots with runoff collection gutters installed at 3.0-m intervals along the lengths of the plots. Runoff was generated from simulated rainfall (50 mm/h for 1 h of runoff), and samples were analyzed for total Kjeldahl N (TKN), organic N (Org-N), ammonia N (NH3-N), nitrate N (NO3-N), total P (TP), total organic C (TOC), and total suspended solids (TSS). Soluble fractions of TKN, Org-N, NH3-N, TP, and TOC were also determined. Manure-treated length had no effect on runoff concentration of any parameter, indicating that a manure-treated length of only 3.0 m would have been sufficient to simulate runoff quality associated with longer manure length treatments. Proportions of TKN, Org-N, NH3-N, and TP transported in soluble form were high (≥ 74%), and over half of the TOC in the runoff was in soluble form. These results indicate that for conditions similar to those of this study, extrapolation with respect to runoff concentrations might be possible with little adaptation of the data and might simplify the design of management practices that key on edge-of-field runoff concentrations. The results with regard to modes of transport can help to better model losses of N, P, and COD and suggest that losses of these parameters will be most effectively controlled through practices that focus on reducing soluble losses rather than simply reducing erosion

Can High-risk Older Drivers be Identified in a DMV Setting with a Brief Battery of Functional Tests?

Recent research has indicated that some laboratory measures of functional ability may discriminate between crash-involved and crash-free older adults. However, the ability of these tests to provide the same level of discriminability in a real-world setting such as a Department of Motor Vehicles remains to be established. Therefore, in conjunction with the Maryland Department of Motor Vehicles and the National Highway Traffic Safety Administration, a brief battery of tests was developed and evaluated. The battery contained a number of cognitive tests (e.g., UFOV® subtest 2, the closure subtest of the Motor Free Visual Perception Test [MVPT], Trails A and B, etc.) and physical measures (e.g., Rapid Pace Walk, Head and Neck Rotation, etc.) that prior literature had indicated might be related to crash risk in older adults. Motor Vehicle Administration staff were trained to administer the test battery. Older adults (N=4,173, mean age =69 years) were approached by the staff after license renewal and asked to help evaluate the brief battery. Of the 4,173 older adults approached at the field sites, 2,112 individuals aged 55-96 years of age participated. The primary outcome of interest for this study was the occurrence of an at-fault Motor Vehicle Collision (MVC) following assessment. For members of this sample, the outcome period ranged from 2-3 years. Rate Ratios were determined for each functional variable based upon at-fault crashes adjusted for driving exposure over this period. Univariate analyses revealed that five variables (Age, Walk Time, MVPT, Trails A and UFOV®) were significantly related to crash frequency. These significant variables overlapped with one another to a certain degree, indicating that impaired older drivers score poorly on multiple cognitive assessments. The UFOV® subtest 2 appears to be the most strongly associated within this analysis (RR=3.78, p\u3c .05) and Rapid Pace Walk (RR=1.96, p \u3c .05) remained uniquely related to the frequency of state-reported, at-fault crashes. The role of such a screening battery in field settings such as a DMV will be discussed

Quality of Runoff from Four Northwest Arkansas Pasture Fields Treated with Organic and Inorganic Fertilizer

Long-term land application of animal manures, even at agronomic rates, can promote accumulation of soil phosphorus (P) which can, in turn, contribute to increased P loadings to downstream waters. The objective of this study was to assess the soil and runoff effects of replacing animal manure as a soil amendment with inorganic fertilizer (ammonium nitrate, NH4NO3) on fields that had been treated previously with animal manures. Runoff from two pairs of small fields (0.57 to 1.46 ha) was sampled from September 1991 to April 1994. All fields had been treated previously with animal manures; after runoff monitoring began, one field of each pair received only NH4NO3, while the other of each pair continued to receive animal manure. Both soil and runoff P concentrations exhibited statistically significant decreasing trends over the monitoring period. The results demonstrate the potential for positively influencing runoff quality in a relatively short duration by replacing animal manures with ammonium nitrate for fields already having sufficient soil P

Performance of Vegetative Filter Strips with Varying Pollutant Source and Filter Strip Lengths

Vegetative filter strips (VFS) can reduce runoff losses of pollutants such as nitrogen (N) and phosphorus (P) from land areas treated with fertilizers. While VFS effectiveness is considered to depend on lengths of pollutant source and VFS areas, there is little experimental evidence of this dependence, particularly when the pollutant source is manure-treated pasture. This study assessed the effects of pollutant source area (fescue pasture treated with poultry litter) length and VFS (fescue pasture) length on VFS removal of nitrate N (NO3-N), ammonia N (NH3-N), total Kjeldahl N (TKN), ortho-P (PO4-P), total P (TP), total organic carbon (TOC), total suspended solids (TSS), and fecal coliform (FC) from incoming runoff. This research examined poultry litter-treated lengths of 6.1, 12.2, and 18.3 m, with corresponding VFS lengths of up to 18.3 m, 12.2 m, and 6.1 m, respectively. Runoff was produced from simulated rainfall applied to both the litter-treated and VFS areas at 50 mm/h for 1 h of runoff. Pollutant concentrations in runoff were unaffected by litter-treated length but demonstrated a first-order exponential decline with increasing VFS length except for TSS and FC. Runoff mass transport of NH3-N,TKN, PO4-P, TP and TOC increased with increasing litter-treated length (due to increased runoff) and decreased (approximately first-order exponential decline) with increasing VFS length when affected by VFS length. Effectiveness of the VFS in terms of NH3-N, TKN, PO4-P, TP and TOC removal from runoff ranged from 12-75, 22-67, 22-82, 21-66, and 8-30% respectively. The data from this study can help in developing and testing models that simulate VFS performance and thus aid in the design of VFS installed downslope of pasture areas treated with animal manure

Effectiveness of Vegetative Filter Strips in Controlling Losses of Surface-Applied Poultry Litter Constituents

Vegetative filter strips (VFS) have been shown to have high potential for reducing nonpoint source pollution from cultivated agricultural source areas, but information from uncultivated source areas amended with poultry litter is limited. Simulated rainfall was used in analyzing effects of VFS length (0, 3.1, 6.1, 9.2, 15.2, and 21.4 m) on quality of runoff from fescue (Festuca arundinacea Schreb.) plots (1.5 x 24.4 m) amended with poultry litter (5 Mg/ha). The VFS reduced mass transport of ammonia-nitrogen (NH3-N), total Kjeldahl nitrogen (TKN), ortho-phosphorus (PO4-P), total phosphorus (TP), chemical oxygen demand (COD), and total suspended solids (TSS). Mass transport of TKN, NH3-N, TP, and PO4-P were reduced by averages of 39, 47, 40, and 39%, respectively, by 3.1 m VFS and by 81, 98, 91, and 90%, respectively, by 21.4 m VFS. Effectiveness of VFS in terms of mass transport reduction was unchanged, however, beyond 3.1 m length for TSS and COD and averaged 35 and 51%, respectively. The VFS were ineffective in removing nitrate-nitrogen from the incoming runoff. Removal of litter constituents was described very well (r2 = 0.70 to 0.94) by a first-order relationship between constituent removal and VFS length

Vegetative Filter Strip Removal of Metals in Runoff from Poultry Litter-Amended Fescuegrass Plots

Runoff from land areas amended with poultry (Gallus gallus domesticus) manure can contain elevated concentrations of metals such as Cu, Fe, and Zn. Vegetative filter strips (VFS) can reduce runoff concentrations of animal manure components, but reported studies have typically focused on nutrients and solids rather than metals. This experiment assessed the impact of VFS length (0 to 12 m) on concentrations and mass losses of Cu, Fe, K, Na, Ni, and Zn in runoff from fescuegrass (Festuca arundinacea Schreb.) plots (1.5 m wide × 6 and 12 m long) treated with poultry litter. The runoff was produced from simulated rainfall applied at 50 mm h-1 until 1 h of runoff had occurred. Runoff Ni concentrations were below detection levels in all cases. Concentrations of Cu, Fe, K, Na, and Zn did not differ between litter-treated plot lengths but were significantly (p \u3c 0.001) affected by VFS length, decreasing in an approximately firstorder fashion. Means separation indicated that concentrations of Cu, Fe, K, and Zn did not significantly decrease after a VFS length of 3 m, while Na concentrations decreased up to a VFS length of 6 m. Mass transport of only Cu significantly decreased with increasing VFS, suggesting that VFS removal mechanisms such as adsorption to clay particles might play a larger role with regard to Cu than to Fe, K, Na, and Zn

Application of Simplified Phosphorus Transport Models to Pasture Fields in Northwest Arkansas

Runoff transport of phosphorus (P) is often predicted from simple equations with parameters determined from data applicable primarily to row-cropped and fallow cover conditions. The applicability, accuracy, and precision of such P transport prediction equations under pasture situations are less well defined. The objectives of this study were to determine parameters of simplified runoff P transport equations for pasture fields and to assess the accuracy and precision of the equations. Runoff, sediment yield, soluble P transport, and particulate P transport data were collected from four pasture fields in northwestern Arkansas. Runoff event enrichment ratios and extraction coefficients were computed, and confidence limits on respective predicted particulate and soluble P transport were determined. An inverse linear relationship between the natural logarithms of enrichment ratio and sediment yield was found significant for all fields, but the slopes were lower than values reported earlier for general use. Runoff event extraction coefficients were considerably higher than those typically used and were highest for runoff occurring shortly following animal manure application. The 95% confidence limits on predicted soluble and particulate P transport varied in some cases by more than an order of magnitude, indicating that significant imprecision was associated with those predictions. The data suggested that the simplified model of soluble P transport might be a reasonable description of the processes for the fields, but that modification to the particulate P transport prediction method might be necessary to improve the prediction accuracy for low event sediment yields (\u3c 10 kg/ha)

Indicator Bacteria Concentrations of Two Northwest Arkansas Streams in Relation to Flow and Season

Concentrations of indicator bacteria such as fecal coliform (FC) and fecal streptococcus (FS) are often used to assess the suitability of waters for their intended use(s) and to allocate resources for water quality improvement measures. There is evidence, however, that concentrations of FC and FS can be influenced by variables such as season and flow rate during sampling, which could lead to biased results. The objective of this study was to assess the impacts of season and flow rate on concentrations of FC and FS. Fecal indicator bacteria concentrations were measured for approximately three years at five sites on two Northwest Arkansas streams. Flow data were collected at two of the five sites. Land use in the basins draining the streams was primarily pasture (57-90%) and forest (6-40%). Significant seasonal influences on FC and FS concentrations were detected for all sampling sites, with the highest concentrations occurring in summer. On the two sites with flow data, flow rate generally had a significant effect on FC and FS concentrations during all seasons, with FC and FS concentrations increasing with flow rate. Ratios of FC and FS, which have been used in the past to differentiate between animal and human sources of fecal pollution, did not appear to reliably indicate the major sources of fecal indicator bacteria. The findings of this study suggest a potential for fixed sampling intervals to contribute to biased results. The issue of biased results might be avoided by sampling during times of year and flow conditions that support the intended use(s) of the waters

Effect of BMP Implementation on Storm Flow Quality of Two Northwestern Arkansas Streams

The effectiveness of management practices in improving quality of runoff from agricultural land areas has been reported based primarily on results from plot- and field-scale studies. There is limited information available on watershed scales, particularly when the dominant agricultural land use is pasture. The objective of this study was to determine whether a program of Best Management Practice (BMP) implementation in the Lincoln Lake watershed of northwestern Arkansas was effective in reducing storm stream flow concentrations and mass transport of nitrate nitrogen (NO3-N), ammonia nitrogen (NH3-N), total Kjeldahl nitrogen (TKN), ortho-phosphorus (PO4-P), total phosphorus (TP), chemical oxygen demand (COD), and total suspended solids (TSS). Storm flow quality of the two main tributaries to Lincoln Lake was monitored from September 1991 to April 1994. Significant decreases (from 23 to 75% per year) in both concentrations and mass transport of NO3-N, NH3-N, TKN, and COD occurred concurrently with BMP implementation. The decreases in nitrogen and COD concentrations and mass transport are attributed to BMP implementation, and the BMP most responsible for these decreases is most likely nutrient management