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In some high‐fertility, high‐stocking‐density grazing systems, nitrate (NO3) leaching can be great, and ground water NO3–N concentrations can exceed maximum contaminant levels. To reduce high N leaching losses and concentrations, alternative management practices need to be used. At the North Appalachian Experimental Watershed near Coshocton, OH, two management practices were studied with regard to reducing NO3–N concentrations in ground water. This was following a fertilized, rotational grazing management practice from which ground water NO3–N concentrations exceeded maximum contaminant levels. Using four small watersheds (each approximately 1 ha), rotational grazing of a grass forage without N fertilizer being applied and unfertilized grass forage removed as hay were used as alternative management practices to the previous fertilized pastures. Ground water was sampled at spring developments, which drained the watershed areas, over a 7‐yr period. Peak ground water NO3–N concentrations before the 7‐yr study period ranged from 13 to 25.5 mg L−1Ground water NO3–N concentrations progressively decreased under each watershed and both management practices. Following five years of the alternative management practices, ground water NO3–N concentrations ranged from 2.1 to 3.9 mg L−1Both grazing and haying, without N fertilizer being applied to the forage, were similarly effective in reducing the NO3–N levels in ground water. This research shows two management practices that can be effective in reducing high NO3–N concentrations resulting from high‐fertility, high‐stocking‐density grazing systems, including an option to continue grazing.

Potassium bromide was applied at a rate of 168 kg Br−/ha to two 1.1‐ha pasture watersheds in east‐central Ohio to study the impacts on groundwater quality of a one‐time application of a soluble constituent. The watersheds had well‐drained residual silt loam soils and average slopes of about 20%. A nearly impermeable clay layer under the watersheds created a perched aquifer from which groundwater samples could be taken at developed springs. Three monolith, grassed lysimeters having soil profiles similar to the watersheds also received the Br−1treatment. The lysimeters, which were 8 m2in surface area and had a depth of 2.4 m, had shorter leaching pathways than the watersheds and showed peak Br−1concentrations in percolation (24.0 mg/L maximum peak) occurring 52–78 weeks following the Br−1application. The Br−1concentration in the groundwater from the watersheds had lower peaks (9.2 mg/L maximum peak) but occurred 84 to 104 weeks after the Br−1application. Because of variable leaching pathway lengths, including pathways much longer than those in the lysimeters, the watershed groundwater Br−1applications had shown no meaningful decrease by 2 yrs after the Br−1application. A one‐time application of a soluble, nondegradable chemical constituent can have a multi‐year influence on groundwater quality.

Four small, medium fertility (56 kg/ha per year N) watersheds were used in a rotational summer‐grazing and winter‐feeding program to determine its effects on N levels in water. During a 5‐year study on sloping uplands in Ohio, the concentrations of NO3‐N and NH4‐N were determined in precipitation, surface runoff, subsurface flow, and sediment. Although the NO3‐N concentration was generally higher in the surface runoff from the summer‐grazing/winter‐feeding area than from the summer‐grazing‐only areas, it usually resulted in no significant impairment of water quality, except on a few occasions when the NO3‐N concentration exceeded 10 mg/liter. The N transported in the subsurface flow from the summer‐grazing only areas was approximately equal to that transported from the winter‐feeding area and to the amount of N received in the precipitation. Both surface runoff transport and sediment transport of N were much greater in the winter‐feeding area than in the summer‐grazing‐only areas because these latter areas yielded very little surface runoff and only a trace of soil loss. Reduction of vegetative cover and increased soil disturbance on the winter‐feeding area resulted in increased surface runoff and soil erosion and thus more N was transported. Surface and subsurface losses of N from the winter‐feeding area were nearly equal. A large percentage of N was transported by the large storms, which represented a small percentage of the total number of storms.

Four small, sloping upland watersheds in Ohio (0.5–1.1 ha) were studied for 5 years to investigate hydrologic and soil erosion changes resulting from a beef cattle pasturing program. The cattle grazed all four pastures rotationally during the summer (May–October) and were wintered on hay (November–April) on the same pasture each year. The long‐term record for these pastures, which had been in meadow and light pasturing during the previous years, showed average annual surface runoff to be approximately 15 mm. During the 5 years of the grazing project, the three summer‐grazing‐only pastures showed a slight increase in surface runoff and a trace of soil loss. However, the winter‐feeding/summer‐grazing area showed a large increase in surface runoff (131 mm/year) and soil loss (1,355 kg/ha per year). Eighty‐one percent of the soil loss occurred during the dormant season. Large runoff events, although a small percentage of the total number of events, produced most of the runoff volume and most of the soil loss. Water balance studies indicated that subsurface flow was relatively unchanged by the grazing program. The increase in surface runoff was offset by a decrease in the evapotranspiration.

Each year for 3 y, 56 steer calves were fed to market weight on a corn‐silage and shelled‐corn ration in a 243‐m2paved lot. Storm runoff was measured and sampled as it left the feedlot, and again after it passed through a shallow, concrete settling basin and two consecutive 30 m long by 4.5 m wide sod filter strips. Storm runoff amounts and transport of TS (total solids), COD (chemical oxygen demand), BOD5(5‐d biological oxygen demand), N (total nitrogen), and P (total phosphorus) were smaller during the fall and winter months, when the steers were small and being fed silage than during May through July, when the animals were larger and eating shelled corn. The settling basin reduced transport of TS and COD by about 55%, while retaining only 35–40% of the BOD5, N, and P. Total reduction of all parameters was increased to 80–90% in the filter strips. The basin was more effective in large storm events, and the filter strips were more effective when the basin was slowly drained after settling of the settleable solids. Rainfall on the filter strips reduced the concentration of all parameters during large storms, and infiltration during other events reduced transport to downstream areas.

A beef cattle‐pasturing system involving four rotationally grazed summer pastures (SG) and four pastures used rotationally for winter grazing/feeding (WGF) was studied on sloping upland watersheds in Ohio to determine effects of livestock management on N levels in water. Both summer and winter areas annually received 224 kg N/ha as NH4NO3fertilizer. Surface runoff was collected automatically during runoff events, and subsurface flow was sampled from spring developments on a weekly basis. Although seasonal N concentration and transport in surface runoff tended to be greater in the area occupied by the cattle, N concentration and transport in runoff from the two areas were quite similar and did not significantly impair water quality, based on U.S. Public Health Standards. The NO3‐N concentration in the subsurface flow from the WGF area was higher than in the subsurface flow from the SG area. The NO3‐N concentration in the subsurface flow from both areas increased progressively throughout the study period, and reached levels as high as 18 mg/L. The subsurface flow provided the main pathway for N transport, with the surface transport being approximately 20 and 14% of the total N transport from the SG and WGF areas, respectively. The amount of sediment‐N transported was very small because of low soil loss.

Five small watersheds (0.25–3.1 ha) on sloping uplands in eastern Ohio were used to evaluate environmental effects of a beef management program of rotational summer grazing on one area, and rotational winter grazing/feeding with stored hay on another area. During the 5‐y study, annual precipitation was 1080 mm, which was 8–15% greater than the long‐term average. The surface runoff was measured by precalibrated H‐flumes, and automatically sampled using Coshocton wheels. Surface runoff from watersheds with beef cattle management increased, compared with the long‐term averages when hay was grown on the watersheds. Greater precipitation was the primary factor causing more runoff during the growing season (May–October), and the cattle management was a major contributing influence on the runoff increase during the dormant season (November–April). Maintenance of good vegetative cover on the study areas was a major factor in limiting annual average surface runoff to < 110 mm, which was a relatively small amount. The large runoff events, although a small percentage of the total number of events, produced most of the runoff volume. Soil loss from these pastures was minimal.

The influence of pasturing on surface runoff water quality was studied on a 26‐ha, unimproved pasture watershed in eastcentral Ohio. Data were collected for 2 y with no cattle in the pasture and for 3 y with summer grazing by a 17‐cow beef cattle herd. Because of springs and seep areas in the pasture, a small stream (accessible to the cattle) in the watershed flowed permanently. Samples of storm runoff were collected with a rotating vane sampler. The concentrations of most of the measured chemical parameters (NO3‐N, mineral N, organic N, total P, K, Ca, Mg, Na, S, Cl, HCO3, total organic C, salts) in the storm discharge water were low and changed very little as a result of grazing. The weighted annual NO3‐N concentrations for the ungrazed period and grazed period were 0.5 and 0.7 mg/L, respectively, and the highest event concentrations were 1.2 and 3.8 mg/L, respectively. A 17.7‐ha, wooded watershed that contained no pastured areas and received no agricultural chemical inputs, had concentrations of chemical parameters in surface discharge that were greater than or equal to those from the unimproved pasture during the grazing period. Nutrient transport during storm runoff from the unimproved pasture was greater during the 3‐y period with summer grazing than during the 2‐y, ungrazed period. This largely resulted from increased precipitation and subsequent increased surface runoff during the 3‐y period. The transport levels from the pasture during the 3‐y period were similar to or less than the transport levels from the wooded watershed during the same period. The increase in sediment transport from the pastured area was more than could be attributed solely to the increased surface runoff.

A common practice for grazing land in the humid, eastern USA is continuous grazing with little or no fertilizer use. Concentrations and transport of nutrients from a 28‐ha unimproved grassed watershed were assessed in east‐central Ohio for 2 yr without the presence of livestock, for 3 yr with a 17‐cow beef (Bos taurus) herd grazing during the summer months only, and for an additional 6‐yr period with all‐year grazing with hay being brought in for winter feed. Nutrient concentrations remained low during all three grazing levels. An exception was K concentration, which increased with all‐year grazing. Concentrations of NO3‐N, mineral‐N, P, Ca, Mg, Na, and Cl were similar to or less than the concentrations from a nearby 17.7‐ha wooded watershed that contained no pastured areas and received no agricultural inputs. Nutrient concentrations showed no consistent seasonal variation. Concentrations of organic‐N, total organic C and sediment increased with increased grazing pressure. Greatest sediment concentrations and transport rates generally occurred during July and August regardless of grazing system. Largest monthly average sediment concentrations were 0.8, 1.3, and 3.2 g/L for the three systems, respectively; annual sediment losses were 0.2, 1.2, and 2.1 Mg/ha, respectively. All‐year cattle grazing/feeding on an unimproved pasture in this area would not be expected to produce degradation of stream water quality from nutrient concentrations or transport.

Three monolith lysimeters, each with a surface area of 8.1 m2and a depth of 2.4 m, were planted to no‐till corn (Zea maysL.) for 6 consecutive years. The lysimeters contained a Rayne silt loam (Typic Hapludult), a well‐drained residual soil. Urea was placed in a slot approximately 10‐cm deep and 10 to 15 cm from the corn row at a rate of 336 kg N/ha. The urea applied to two of the lysimeters was treated with nitrapyrin [2‐chloro‐6‐(trichloromethyl)pyridine], a nitrification inhibitor, and applied untreated on the third lysimeter. Two years of unfertilized meadow immediately preceded the corn. Concentrations of NO−3; in the leachate from the lysimeters were higher during the corn years than during the meadow period. Concentrations showed seasonal variations during the last 3 yr of the study, but showed no increasing trend. The leachate from the lysimeters receiving the nitrapyrin treated urea had seasonally flow‐weighted NO−3; concentrations ranging from 6 to 40 mg/L, while the leachate from the lysimeter receiving untreated urea had seasonally flow‐weighted NO−3;‐N concentrations ranging from 20 to 54 mg/L. Nitrate‐N losses showed a similar treatment difference. The 6‐yr annual average NO−3; loss was 117 and 160 kg/ha from the lysimeters with the treated urea and untreated urea, respectively. This study demonstrates that nitrification inhibitors such as nitrapyrin, have a potential to reduce NO−3; leaching when applied with ammoniacal fertilizers.

High levels of N fertilizer applied to pastures can result in NO3‐N concentrations in groundwater exceeding the USEPA potable water standard of 10 mg N/L. This study was conducted to determine groundwater NO3‐N levels following a change in N source from fertilizer to a legume in a grass‐pasture grazed by beef cattle. For 5 yr, 224 kg N/ha was applied annually to small watersheds with orchardgrass (Dactylis glomerataL.) pastures used for summer‐grazing and tall fescue (Festuca arundinaceaSchreb.) areas used for winter‐grazing‐feeding. At the beginning of the sixth year, alfalfa (Medicago sativaL.) was interseeded into the grass pastures and N fertilizer was no longer applied. Groundwater sampies from developed springs and surface runoff samples were collected and analyzed for NH4‐N, NO3‐N, and total N for the 5‐yr fertilization period and for the following 10‐yr period without applied N fertilizer. Nitrogen in groundwater was present mainly in the NO3form, and concentrations increased throughout the 5‐yr period of fertilizer application and reached levels that were usually in excess of 10 mg N/L. With the change from N fertilizer to legume N, the NO3‐N concentrations in groundwater dropped rapidly during a 2‐yr period. In a tall fescue‐alfalfa area, NO3‐N levels decreased from 17.7 to 9.3 mg N/L. In two orchard‐grass‐alfalfa areas, NO3‐N levels decreased from 11.2 to 2.7 and from 8.3 to 3.6 mg N/L. During the remainder of the 10‐yr period, NO3‐N concentrations declined to levels similar to those before N fertilization. Although the amount of N lost via subsurface flow decreased with decreasing concentrations, subsurface flow remained the main pathway for N loss compared with surface runoff or sediment‐attached N.