QUALITY OF RUNOFF FROM PLOTS WITH SIMULATED GRAZING1

ABSTRACT: Grazed pastures represent a potential source of non‐point pollution. In comparison to other nonpoint sources (e.g., row‐cropped lands), relatively little information exists regarding possible magnitudes of nutrient losses from grazed pasture, how those losses are affected by management variables, and how the losses can be minimized. The objective of this study was to measure concentrations of nitrogen (N), phosphorus (P), and solids in runoff from fescue plots and relate those measurements to simulated forage management strategy. The study was conducted at the University of Kentucky Maine Chance Agricultural Experiment Station north of Lexington. Plots (2.4 m wide by 6.1 m long) were constructed and established in Kentucky 31 fescue (Festuca arundinacea Schreb.) to represent pasture. The experimental treatments applied to the plots varied in terms of forage height and material applied (none, manure, or manure and urine). Runoff was sampled for six simulated rainfall events applied over the summer of 1997 and analyzed for nitrate N (NO₃‐N), ammonia N (NH3‐N), total Kjeldahl N (TKN), ortho‐P (PO₄‐P), total P (TP), and total suspended solids (TSS). All runoff constituents exhibited dependence on the date of simulated rainfall with generally higher concentrations measured when simulated rainfall followed relatively dry periods. The effects of forage height and manure addition were mixed. Highest runoff N concentrations were associated with the greatest forage heights, whereas highest P concentrations occurred for the least forage heights. Manure/urine addition increased runoff P concentrations relative to controls (no manure/urine) for both the greatest and least forage heights, but runoff N concentrations were increased only for the greatest forage heights. These findings indicate that runoff of N and P is at least as sensitive to amount and proximity of preceding rainfall and suggest that managing forage to stimulate growth and plant uptake can reduce runoff of N.     

FECAL COLIFORM AND STREPTOCOCCUS CONCENTRATIONS IN RUNOFF FROM GRAZED PASTURES IN NORTHWEST ARKANSAS1

ABSTRACT: Agricultural practices such as cattle grazing and animal manure application can contribute to relatively high runoff concentrations of fecal coliform (FC) and fecal streptococcus (FS). Available information, however, is inconsistent with respect to the effects of such practices as well as to measures that can discriminate among candidate sources of FC and FS. The objective of this study was to assess the effects of grazing, time of year, and runoff amounts on FC and FS concentrations and to evaluate whether FCIFS concentration ratios are consistent with earlier values reported as characteristic of animal sources. Runoff from four Northwest Arkansas fields was sampled and analyzed for fecal coliform (FC) and fecal streptococcus (FS) for nearly three years (1991–1994). Each field was grazed and fertilized, with two fields receiving inorganic fertilizer and two receiving animal manure. Runoff amount had no effect on runoff concentrations of FC or FS. There were no consistent relationships between the presence of cattle and FC and FS runoff concentrations. Both FC and FS concentrations were affected by the season during which the runoff occurred. Higher concentrations were observed during warmer months. Runoff FC concentrations exceeded the primary contact standard of 200 cfu/100 mL during at least 89 percent of all runoff events and the secondary contact standard of 1000 cfu/100 mL during at least 70 percent of the events. Ratios of FC to FS concentrations varied widely (from near zero to more than 100), confirming earlier findings that FC/FS ratios are not a reliable indicator of the source of FC and FS.     

A COMPARISON OF RUNOFF QUALITY EFFECTS OF ORGANIC AND INORGANIC FERTILIZERS APPLIED TO FESCUEGRASS PLOTS1

ABSTRACT: Application of fertilizer can degrade quality of runoff, particularly during the first post-application, runoff-producing storm. This experiment assessed and compared runoff quality impacts of organic and inorganic fertilizer application for a single simulated storm occurring seven days following application. The organic fertilizers used were poultry (Gallus gallus domesticus) litter, poultry manure, and swine (Sus scrofa domesticus) manure. All fertilizers were applied at an application rate of 217.6 kg N/ha. Simulated rainfall was applied at 50 mm/h for an average duration of 0.8 h. Runoff samples were collected, composited, and analyzed for nitrate N (NO₃-N), ammonia N (NH₃-N), total Kjeldahl N (TKN), ortho-P (PO₄-P), total P (TP), chemical oxygen demand (COD), total suspended solids (TSS), fecal coliforms (FC), and fecal streptococci (FS). Application of the fertilizers did not alter the hydrologic characteristics of the receiving plots relative to the control plots. Concentrations of fertilizer constituents were almost always greater from treated than from control plots and were usually much greater. Flow-weighted mean concentrations of NH₃-N, PO₄-P, and TP were highest for the inorganic fertilizer treatment (42.0, 26.6, and 27.9 mg/L, respectively). Runoff COD and TSS concentrations were greatest for the poultry litter treatment. Concentrations of FC and FS were greater for fertilized than for control plots with no differences among fertilized plots, but FC concentrations for all treatments were in excess of Arkansas' primary and secondary contact standards. Mass losses of fertilizer constituents were low (≤ 3 kg/ha) and were small proportions (≤ 3 percent) of amounts applied.     

RUNOFF OF METALS FROM ALUM-TREATED HORSE MANURE AND MUNICIPAL SLUDGE1

ABSTRACT: Land application of organic soil amendments can increase runoff concentrations of metals such as Fe and Zn, metalbids such as B and As, and non-metals such as P and S that have the potential for causing adverse environmental impacts. Aluminum sulfate, or alum (Al₂(SO₄)3*(14H₂O), can reduce concentrations of some materials in runoff from sites treated with organic amendments. The objectives of this study were to (a) quantify concentrations of selected constituents (Al, As, B, Ca, Cd, Co, Fe, K, Mg, Mn, Mo, Na, P, Pb, 5, Se, Ti, and Zn) in runoff from plots treated with horse manure (mixed with stall bedding) and municipal sludge, (b) assess runoff quality effects of alum addition to those treatments, and (c) determine time variations in concentrations of the constituents. Horse manure and municipal sludge were applied to twelve 2.4 by 6.1 m fescue plots (six each for the manure and sludge). Alum was added to three of the manure-treated and three of the sludge-treated plots. Simulated rainfall (64 mm/h) was applied to the 12 treated plots and to three control (no treatment) plots. The first 0.5 h runoff was sampled and analyzed for the constituents described above. Addition of manure or sludge had no effect on runoff concentrations of the majority of constituents. In some cases (e.g., Al, As, Fe, Zn), however, concentrations were near or in excess of threshold values recommended for marine wildlife protection. Alum addition increased runoff of Al, Ca, K, and 5, due likely to its composition and by the addition of lime to counteract the acidity of alum. Concentration decreases of more than 50 percent were noted for P for the horse manure treatment. No alum effect was detected for P in runoff from the sludge-treated plots, possibly due to relatively stable P forms in the sludge. Runoff concentrations of Al, As, Fe, K, Mn, and P followed an approximately first-order decline with respect to time. Runoff concentrations of Ca and 5, however, peaked during the second runoff sample (four minutes following initiation of runoff), suggesting that differences in mobility and/or transport mechanisms exist among the materials investigated.     

Demonstration of methods to reduce E. coli runoff from dairy manure application sites

Contamination by bacteria is a leading cause of impairment in U.S. waters, particularly in areas of livestock agriculture. We evaluated the effectiveness of several practices in reducing Escherichia coli levels in runoff from fields receiving liquid dairy (Bos taurus) manure. Runoff trials were conducted on replicated hay and silage corn (Zea mays L.) plots using simulated rainfall. Levels of E. coli in runoff were approximately 10(4) to 10(6) organisms per 100 mL, representing a significant pollution potential. Practices tested were: manure storage, delay between manure application and rainfall, manure incorporation by tillage, and increased hayland vegetation height. Storage of manure for 30 d or more consistently and dramatically lowered E. coli counts in our experiments, with longer storage providing greater reductions. Manure E. coli declined by > 99% after approximately 90 d of storage. On average, levels of E. coli in runoff were 97% lower from plots receiving 30-d-old and > 99% lower from plots receiving 90-d-old manure than from plots where fresh manure was applied. Runoff from hayland and cornland plots where manure was applied 3 d before rainfall contained approximately 50% fewer E. coli than did runoff from plots that received manure 1 d before rainfall. Hayland vegetation height alone did not significantly affect E. coli levels in runoff, but interactions with rainfall delay and manure age were observed. Manure incorporation alone did not significantly affect E. coli levels in cornland plot runoff, but incorporation could reduce bacteria export by reducing field runoff and interaction with rainfall delay was observed. Extended storage that avoids additions of fresh manure, combined with application several days before runoff, incorporation on tilled land, and higher vegetation on hayland at application could substantially reduce microorganism loading from agricultural land.     

Surface runoff losses of phosphorus from Virginia soils amended with turkey manure using phytase and high available phosphorus corn diets

Many states have passed legislation that regulates agricultural P applications based on soil P levels and crop P uptake in an attempt to protect surface waters from nonpoint P inputs. Phytase enzyme and high available phosphorus (HAP) corn supplements to poultry feed are considered potential remedies to this problem because they can reduce total P concentrations in manure. However, less is known about their water solubility of P and potential nonpoint-source P losses when land-applied. This study was conducted to determine the effects of phytase enzyme and HAP corn supplemented diets on runoff P concentrations from pasture soils receiving surface applications of turkey manure. Manure from five poultry diets consisting of various combinations of phytase enzyme, HAP corn, and normal phytic acid (NPA) corn were surface-applied at 60 kg P ha(-1) to runoff boxes containing tall fescue (Festuca arundinacea Schreb.) and placed under a rainfall simulator for runoff collection. The alternative diets caused a decrease in manure total P and water soluble phosphorus (WSP) compared with the standard diet. Runoff dissolved reactive phosphorus (DRP) concentrations were significantly higher from HAP manure-amended soils while DRP losses from other manure treatments were not significantly different from each other. The DRP concentrations in runoff were not directly related to manure WSP. Instead, because the mass of manure applied varied for each treatment causing different amounts of manure particles lost in runoff, the runoff DRP concentrations were influenced by a combination of runoff sediment concentrations and manure WSP.     

CONTROLLING PHOSPHORUS IN RUNOFF FROM LONG TERM DAIRY WASTE APPLICATION FIELDS1

ABSTRACT: Phosphorus (P) in runoff from long term animal waste application fields can contribute to accelerated eutrophication of surface waters. Manure when applied at nitrogen (N) agronomic rates generally increases soil P concentrations, which can increase runoff of soluble P. Along the North Bosque River in central Texas, dairy waste application fields are identified as the most controllable nonpoint source of soluble P in a total maximum daily load. To evaluate P reduction practices for fields high in soil extractable P, edge‐of‐field runoff was measured from paired plots of Coastal bermudagrass (Cynodon dactylon) and sorghum (Sorghum bicolor)/ winter wheat (Triticum spp.). Plots (about 0.4 ha) received manure at P agronomic rates following Texas permit guidelines and commercial N during the pretreatment period. During the post‐treatment period, control plots continued to receive manure at P agronomic rates and commercial N. Treatment plots received only commercial N during the post‐treatment period. Use of only commercial N on soils with high extractable P levels significantly decreased P loadings in edge‐of‐field runoff by at least 40 percent, but runoff concentrations sometimes increased. No notable changes in extractable soil P concentrations were observed after five years of monitoring due to drought conditions limiting forage uptake and removal.     

Effects of alum and aluminum chloride on phosphorus runoff from swine manure

Phosphorus (P) runoff from fields fertilized with swine (Sus scrofa domesticus) manure may contribute to eutrophication. The objective of this study was to evaluate the effect of aluminum sulfate (alum) and aluminum chloride applications to swine manure on P runoff from small plots cropped to tall fescue (Festuca arundinacea Shreb.). There were six treatments in this study: (i) unfertilized control plots, (ii) untreated manure, (iii) manure with alum at 215 mg Al L(-1), (iv) manure with aluminum chloride at 215 mg Al L(-1), (v) manure with alum at 430 mg Al L(-1), and (vi) manure with aluminum chloride at 430 mg Al L(-1). Manure application rates were equivalent to approximately 125 kg N ha(-1). Alum and aluminum chloride additions lowered soluble reactive phosphorus (SRP) levels from about 130 mg P L(-1) to approximately 30 mg P L(-1) at low rates. At high rates, SRP levels in swine manure were around 1 mg P L(-1). Soluble reactive P concentrations in runoff were 5.50, 3.66, 3.00, 0.87, 0.87, and 0.55 mg P L(-1), for normal manure, low alum, low aluminum chloride, high alum, high aluminum chloride, and unfertilized control plots, respectively. Hence, high alum and aluminum chloride reduced SRP concentrations in runoff by 84% and were not statistically different from SRP concentrations in runoff from unfertilized control plots. These data indicate that treating swine manure with alum or aluminum chloride could result in significant reductions in nonpoint-source P runoff.     

Riparian Grazing Impacts on Streambank Erosion and Phosphorus Loss Via Surface Runoff1

Tufekcioglu, Mustafa, Richard C. Schultz, George N. Zaimes, Thomas M. Isenhart, and Aydin Tufekcioglu, 2012. Riparian Grazing Impacts on Streambank Erosion and Phosphorus Loss via Surface Runoff. Journal of the American Water Resources Association (JAWRA) 1‐11. DOI: 10.1111/j.1752‐1688.2012.12004.x Abstract: Surface runoff is one of the major pathways of sediment and phosphorus (P) transport to surface waters. Rainfall simulations were conducted on nine grazed pasture sites with different stocking rates in three different Iowa (United States) regions. The purpose of the simulations was to determine the impacts of cattle grazing on the amounts of sediment and P in surface runoff within a 15‐m wide strip on both sides of the stream from different source areas (SAs). These riparian SAs included stream‐side loafing areas, cattle streambank access paths to the stream, and the other vegetated areas adjacent to the streambanks. The runoff samples collected during the simulations were analyzed for suspended sediment (SS) and total phosphorus (TP). Soil bulk density and antecedent soil moisture samples were collected around the rainfall simulation plots to identify differences in compaction, infiltration, and surface runoff among the SAs. SS and TP losses from access paths and loafing areas within the 15‐m wide strips accounted for up to 72 and 55% of the total losses, respectively, even though they accounted for only 2.7% of the total area within the 15‐m wide strips. This suggests that access paths and loafing areas require special attention to mitigate the impacts of cattle on stream water pollution. Significant correlations were found between stocking rates and both SS and TP losses suggesting that low stocking rates can reduce sediment and P export to streams from the SAs.     

Nutrient transport from livestock manure applied to pastureland using phosphorus-based management strategies

Land applications of manure from confined animal systems and direct deposit by grazing animals are both major sources of nutrients in streams. The objectives of this study were to determine the effects of P-based manure applications on total suspended solids (TSS) and nutrient losses from dairy manures and poultry litter surface applied to pasturelands and to compare the nutrient losses transported to the edge of the field during overland flow events. Two sets of plots were established: one set for the study of in-field release and another set for the study of edge-of-the-field nutrient transport. Release plots were constructed at three pastureland sites (previous poultry litter applications, previous liquid dairy manure application, and no prior manure application) and received four manure treatments (turkey [Meleagris gallopavo] litter, liquid dairy manure, standard cowpies, and none). Pasture plots with a history of previous manure applications released higher concentrations of TSS and higher percentages of total P (TP) in the particulate form. Transport plots were developed on pasture with no prior manure application. The average flow-weighted TP concentrations were highest in runoff samples from the plots treated with cowpies (1.57 mg L(-1)). Reducing excess P in dairy cow diets and surface applying manure to the land using P-based management practices did not increase N concentrations in runoff. This study found that nutrients are most transportable from cowpies; thus a buffer zone between pastureland and streams or other appropriate management practices are necessary to reduce nutrient losses to waterbodies.     

Rate of fall-applied liquid swine manure: effects on runoff transport of sediment and phosphorus

Reducing the delivery of phosphorus (P) from land-applied manure to surface water is a priority in many watersheds. Manure application rate can be controlled to manage the risk of water quality degradation. The objective of this study was to evaluate how application rate of liquid swine manure affects the transport of sediment and P in runoff. Liquid swine manure was land-applied and incorporated annually in the fall to runoff plots near Morris, Minnesota. Manure application rates were 0, 0.5, 1, and 2 times the rate recommended to supply P for a corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotation. Runoff volume, sediment, and P transport from snowmelt and rainfall were monitored for 3 yr. When manure was applied at the highest rate, runoff volume and sediment loss were less than the control plots without manure. Reductions in runoff volume and soil loss were not observed for spring runoff when frozen soil conditions controlled infiltration rates. The reduced runoff and sediment loss from manure amended soils compensated for addition of P, resulting in similar runoff losses of total P among manure application rates. However, losses of dissolved P increased with increasing manure application rate for runoff during the spring thaw period. Evaluation of water quality risks from fall-applied manure should contrast the potential P losses in snowmelt runoff with the potential that incorporated manure may reduce runoff and soil loss during the summer.     

Managing broiler litter application rate and grazing to decrease watershed runoff losses

Pasture management and broiler litter application rate are critical factors influencing the magnitude of nutrients being transported by runoff from fields. We investigated the impact of pasture management and broiler litter application rate on nutrient runoff from bermudagrass (Cynodon dactylon) pastures. The experiment was conducted on a Ruston fine sandy loam with a factorial arrangement on 21 large paddocks. Runoff water was collected from natural rainfall events from 2001 to 2003. Runoff water and soil samples were analyzed for nutrients and sediments. Runoff was generally greater (29%) from grazed than hayed pastures regardless of the litter application rate. There was greater inorganic N in the runoff from grazed paddocks when litter rate was based on N rather than P. The mean total P loss per runoff event for all treatments ranged from 7 to 45 g ha(-1) and the grazed treatment with litter applied on N basis had the greatest total P loss. Total dissolved P was the dominant P fraction in the runoff, ranging from 85% to 93% of the total P. The soluble reactive P was greater for treatments with litter applied on N basis regardless of pasture management. Runoff total sediments were greater for N-based litter application compared to those which received litter on P basis. Our results indicate that litter may be applied on N basis if the pasture is hayed and the soil P is low. In contrast, litter rates should be based on a P-basis if pasture is grazed.     

Phosphorus and nitrogen in runoff after phosphorus- or nitrogen-based manure applications

Application of beef cattle () manure based on nitrogen (N) requirements of crops has resulted in elevated concentrations of soil test phosphorus (P) in surface soils, and runoff from this cropland can contribute to eutrophication of surface waters. We conducted a 3-yr field study (2005-2007) on a Lethbridge loam soil cropped to dryland barley () in southern Alberta, Canada to evaluate the effect of annual and triennial P-based and annual N-based feedlot manure on P and N in runoff. The manure was spring applied and incorporated. There was one unamended control plot. A portable rainfall simulator was used to generate runoff in the spring of each year after recent manure incorporation, and the runoff was analyzed for total P, total dissolved P, total particulate P, dissolved reactive P, total N, total dissolved N, total particulate N, NO-N, and NH-N. Annual or triennial P-based application resulted in significantly ( ≤ 0.05) lower (by 50 to 94%) concentrations or loads of mainly dissolved P fractions in runoff for some years compared with annual N-based application, and this was related to lower rates of annual manure P applied. For example, mean dissolved reactive P concentrations in 2006 and 2007 were significantly lower for the annual P-based (0.12-0.20 mg L) than for the annual N-based application (0.24-0.48 mg L), and mean values were significantly lower for the triennial P-based (0.06-0.13 mg L) than for the annual N-based application. In contrast, other P fractions in runoff were unaffected by annual P-based application. Our findings suggested no environmental benefit of annual P-based application over triennial P-based application with respect to P and N in runoff. Similar concentrations and loads of N fractions in runoff for the P- and N-based applications indicated that shifting to a P-based application would not significantly influence N in runoff.     

The Effect of Rain and Runoff When Assessing Timing of Manure Application and Dissolved Phosphorus Loss in Runoff1

Vadas, Peter A., William E. Jokela, Dory H. Franklin, and Dinku M. Endale, 2011. The Effect of Rain and Runoff When Assessing Timing of Manure Application and Dissolved Phosphorus Loss in Runoff. Journal of the American Water Resources Association (JAWRA) 47(4):877‐886. DOI: 10.1111/j.1752‐1688.2011.00561.x Abstract: A significant pathway of nonpoint source, agricultural phosphorus (P) transport is surface runoff, to which surface‐applied manure can contribute. Increasing the time between manure application and the first rain‐runoff event is proposed as a practice to reduce runoff P loss. Few studies have investigated this aspect of manure P loss in runoff, with mixed results. Studies observing a decrease in runoff P as the time between application and the first rain‐runoff attribute the decrease to adsorption of manure P by soil and manure drying effects, but do not consider the effect of storm hydrology on runoff P. We ran the manure P runoff model SurPhos with data from nine published studies that investigated the effect of time between application and the first rain event on runoff P. SurPhos successfully simulated the experimental conditions in the studies and predicted runoff P loss. Simulation results suggest soil adsorption of manure P is not the dominant mechanism that will significantly decrease manure P availability to runoff. Rather, regardless of when the first rain‐runoff event occurs, storm hydrology will significantly affect manure P loss in runoff. Although model scenarios indicate that increasing the time between manure application and the first rain‐runoff event will typically decrease P loss in runoff, runoff P could be equal to or greater 30 days after application than the day after application if a more intense rain and runoff event occurs at the latter date.     

Evaluation of phosphorus transport in surface runoff from packed soil boxes

Evaluation of phosphorus (P) management strategies to protect water quality has largely relied on research using simulated rainfall to generate runoff from either field plots or shallow boxes packed with soil. Runoff from unmanured, grassed field plots (1 m wide x 2 m long, 3-8% slope) and bare soil boxes (0.2 m wide and 1 m long, 3% slope) was compared using rainfall simulation (75 mm h(-1)) standardized by 30-min runoff duration (rainfall averaged 55 mm for field plots and 41 mm for packed boxes). Packed boxes had lower infiltration (1.2 cm) and greater runoff (2.9 cm) and erosion (542 kg ha(-1)) than field plots (3.7 cm infiltration; 1.8 cm runoff; 149 kg ha(-1) erosion), yielding greater total phosphorus (TP) losses in runoff. Despite these differences, regressions of dissolved reactive phosphorus (DRP) in runoff and Mehlich-3 soil P were consistent between field plots and packed boxes reflecting similar buffering by soils and sediments. A second experiment compared manured boxes of 5- and 25-cm depths to determine if variable hydrology based on box depth influenced P transport. Runoff properties did not differ significantly between box depths before or after broadcasting dairy, poultry, or swine manure (100 kg TP ha(-1)). Water-extractable phosphorus (WEP) from manures dominated runoff P, and translocation of manure P into soil was consistent between box types. This study reveals the practical, but limited, comparability of field plot and soil box data, highlighting soil and sediment buffering in unamended soils and manure WEP in amended soils as dominant controls of DRP transport.     

Management practice effects on phosphorus losses in runoff in corn production systems

Phosphorus losses in runoff from cropland can contribute to nonpoint-source pollution of surface waters. Management practices in corn (Zea mays L.) production systems may influence P losses. Field experiments with treatments including differing soil test P levels, tillage and manure application combinations, and manure and biosolids application histories were used to assess these management practice effects on P losses. Runoff from simulated rainfall (76 mm h(-1)) was collected from 0.83-m2 areas for 1 h after rainfall initiation and analyzed for dissolved reactive P (DRP), bioavailable P, total P (TP), and sediment. In no-till corn, both DRP concentration and load increased as Bray P1 soil test (STP) increased from 8 to 62 mg kg(-1). A 5-yr history of manure or biosolids application greatly increased STP and DRP concentrations in runoff. The 5-yr manure treatment had higher DRP concentration but lower DRP load than the 5-yr biosolids treatment, probably due to residue accumulation and lower runoff in the manure treatment. Studies of tillage and manure application effects on P losses showed that tillage to incorporate manure generally lowered runoff DRP concentration but increased TP concentration and loads due to increased sediment loss. Management practices have a major influence on P losses in runoff in corn production systems that may overshadow the effects of STP alone. Results from this work, showing that some practices may have opposite effects on DRP vs. TP losses, emphasize the need to design management recommendations to minimize losses of those P forms with the greatest pollution potential.     

SURFACE WATER QUALITY IMPACTS OF TILLAGE PRACTICES UNDER LIQUID SWINE MANIJRE APPLICATION1

ABSTRACT: Field studies were conducted to investigate the effects of tillage practices on the saturated hydraulic conductivity, and quantity and quality of surface runoff water resulting from the application of the liquid swine manure as a fertilizer. As part of the study, infiltration experiments were conducted on silt-loam soil with no-tillage (NT) and disk tillage (DT) practices. Liquid swine manure was applied on test plots, and the rainfall was applied by the portable rainfall simulator. The infiltration data was analyzed for the saturated hydraulic conductivity (K8) and runoff volume determinations. The surface runoff water was analyzed for total N, total P, ammonia, and nitrate concentration determinations. The study indicated that the tillage had significant effects on K_s, and quantity and quality of runoff water. The K_s values of the NT plots were found to vary from 0.693 to 1.734 mm/min, with a mean of 1.494 mm/min, while they varied from 1.056 to 2.543 mm/min, with a mean of 2231 mm/mm in the DT plots. The total N, total P, ammonium nitrogen and nitrate nitrogen concentrations were lower in runoff generated from DT plots, compared to that from the NT plots. The chemical concentration levels were significantly different in runoff waters collected one-day after manure application than in those collected 40-days after the manure application. Study suggested that the DT practice must be preferred over the NT practice if liquid swine manure is used as the fertilizer. The study is further continued to assess the long-term impacts of swine manure application and tillage on the quantity and quality of surface runoff water.     

Manure composition and incorporation effects on phosphorus in runoff following corn biomass removal

Greater demand for corn ( L.) stover for bioenergy use may lead to increased corn production acreage with minimal surface residue cover, resulting in greater risk for soil erosion and phosphorus (P) losses in runoff. A rainfall simulation study was conducted to determine the effects of spring-applied dairy cow () manure (none, in-barn composted, and exterior walled-enclosure pit) with >200 g kg organic solids content following fall corn biomass removal with and without incorporation (chisel plow [CP] and no-till [NT]) on sediment and P in runoff. Runoff was collected from a 0.83-m area for 60 min following the onset of rainfall simulation (76 mm h), once in spring and once in fall. Runoff dissolved reactive P (DRP) and dissolved organic P (DOP) concentrations were positively correlated with manure P rate and were higher in NT compared with CP. Conversely, sediment and particulate P (PP) concentrations in runoff were inversely correlated with manure P rate (and manure solids) and were higher in CP compared with NT. Runoff volume where no manure was applied was higher in NT than in CP in spring but similar in fall. The addition of manure reduced runoff volumes by an average of 82% in NT and 42% in CP over spring and fall. Results from this study indicate that surface application of dairy manure with relatively high solids content may reduce sediment and PP losses in runoff without increasing the risk of increased DRP and DOP losses in the year of application where corn biomass is harvested.     

Residue level and manure application timing effects on runoff and sediment losses

There is growing interest in evaluating the effects of corn silage harvesting methods on erosion control. Increasing the silage cutting height will increase residue cover and could conceivably minimize off-site migration of sediments compared with conventional silage harvesting. The effects of residue level and manure application timing on runoff and sediment losses from no-till corn were examined. Treatments included conventional corn grain (G) and silage (SL) and nonconventional, high-cut (60-65 cm) silage (SH). Corn harvesting treatments were subjected to different manure application regimes: no manure (N) or surface application in fall (F) or spring (S). Simulated rainfall (76 mm/h; 1 h) was applied in spring and fall for two years (2002-2003), runoff from 2.0- x 1.5-m plots collected, and a subsample analyzed for sediment concentration and aggregate size distribution. Runoff volume was inversely related to residue cover. Manure addition to silage plots reduced spring runoff by 71 to 88%, attributable to an increase in soil organic matter content, compared with SH-N and SL-N. Differences in sediment concentration between SH and SL were not significant. For silage plots, spring-applied manure had the greatest influence on sediment export reducing it by 84 to 93% in spring runoff compared with corresponding N plots. Sediment loads were also 85 to 97% lower from SH-S compared with SL-N in all four seasons. Except for spring 2003, sediment export was lower from G compared with SL. The combination of manure and higher residue associated with high-cut silage often lowered sediment export compared with low-cut silage. Nearly identical aggregate size distributions were observed in sediments from SH and SL plots. High residue levels combined with spring-applied manure led to enrichment in the clay-sized fraction of runoff sediment. Recently applied manure and higher residue levels achieved by high-cutting silage can substantially lower sediment losses in spring runoff when soil is most susceptible to erosion.     

Effects of winter manure application in Ohio on the quality of surface runoff

Winter application of manure poses environmental risks. Seven continuous corn, instrumented watersheds (approximately 1 ha each) at the USDA-ARS North Appalachian Experimental Watershed research station near Coshocton, Ohio were used to evaluate the environmental impacts of winter manure application when using some of the Ohio Natural Resources Conservation Service recommendations. For 3 yr on frozen, sometimes snow-covered, ground in January or February, two watersheds received turkey litter, two received liquid swine manure, and three were control plots that received N fertilizer at planting (not manure). Manure was applied at an N rate for corn; the target level was 180 kg N ha(-1) with a 30-m setback from the application area to the bottom of each watershed. Four grassed plots (61 x 12 m) were used for beef slurry application (9.1 Mg ha(-1) wet weight); two plots had 61 x 12 m grassed filter areas below them, and two plots had 30 x 12 m filter areas. There were two control plots. Nutrient concentrations were sometimes high, especially in runoff soon after application. However, most events with high concentrations occurred with low flow volumes; therefore, transport was minimal. Applying manure at the N rate for crop needs resulted in excess application of P. Elevated P losses contributed to a greater potential of detrimental environmental impacts with P than with N. Filter strips reduced nutrient concentrations and transport, but the data were too limited to compare the effectiveness of the 30- and 61-m filter strips. Winter application of manure is not ideal, but by following prescribed guidelines, detrimental environmental impacts can be reduced.