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To interpret the effects of best management practices on water quality at a regional or large watershed scale, likely response times at various scales must be known. Therefore, four small (≤1 ha [≤2.5 ac]) watersheds, in rotational grazing studies at the North Appalachian Experimental Watershed near Coshocton, Ohio, were used to study management impacts on water quality and response times. Surface runoff was sampled on an event basis; groundwater discharge was sampled monthly from springs developed where a perching clay layer outcropped at the soil surface. In four large watersheds ranging from 18 to 123 ha (44 to 303 ac), base flow was over 50% of annual stream flow and approximately 20% of annual precipitation. Nitrate-N loads in base flow were 31% to 59% of total annual NO 3 -N load in stream flow. When the N fertilization rate in a “medium fertility” area that contains two small watersheds was increased from 56 to 168 kg ha -1 y -1 (50 to 150 lb ac -1 yr -1 ), NO 3 -N concentrations in groundwater discharge responded little in four years. Then NO 3 -N levels in groundwater discharge increased for 10 years. With discontinuation of N fertilization, NO 3 -N concentrations in groundwater discharge returned to pre-N increase levels after six years. In a “high fertility” grazing area with a similar perched water table, 224 kg N ha -1 (200 lb ac -1 ) was applied annually. Concentrations of NO 3 -N increased to >10 mg L -1 (ppm) after five years. Legumes were then interseeded into the grass forage, and mineral N fertilization was discontinued. Nitrate-N concentrations in groundwater discharge returned to their pre-fertilization levels after about five years. This multi-year response of groundwater discharge quality to management change in small watersheds indicates that the response time for measurable change in multi-square-mile watersheds will be equally long, if not longer, and trends will be muted.

Received for publication December 15, 2006. Residual herbicides used in the production of soybean [Glycine max (L.) Merr] and corn (Zea mays L.) are often detected in surface runoff at concentrations exceeding their maximum contaminant levels (MCL) or health advisory levels (HAL). With the advent of transgenic, glyphosate-tolerant soybean and glufosinate-tolerant corn this concern might be reduced by replacing some of the residual herbicides with short half-life, strongly sorbed, contact herbicides. We applied both herbicide types to two chiseled and two no-till watersheds in a 2-yr corn-soybean rotation and at half rates to three disked watersheds in a 3-yr corn/soybean/wheat (Triticum aestivum L.)-red clover (Trifolium pratense L.) rotation and monitored herbicide losses in runoff water for four crop years. In soybean years, average glyphosate loss (0.07%) was 1/7 that of metribuzin (0.48%) and about one-half that of alachlor (0.12%), residual herbicides it can replace. Maximum, annual, flow-weighted concentration of glyphosate (9.2 μg L-1) was well below its 700 μg L-1 MCL and metribuzin (9.5 μg L-1) was well below its 200 μg L-1 HAL, whereas alachlor (44.5 μg L-1) was well above its 2 μg L-1 MCL. In corn years, average glufosinate loss (0.10%) was similar to losses of alachlor (0.07%) and linuron (0.15%), but about one-fourth that of atrazine (0.37%). Maximum, annual, flow-weighted concentration of glufosinate (no MCL) was 3.5 μg L-1, whereas atrazine (31.5 μg L-1) and alachlor (9.8 μg L-1) substantially exceeded their MCLs of 3 and 2 μg L-1, respectively. Regardless of tillage system, flow-weighted atrazine and alachlor concentrations exceeded their MCLs in at least one crop year. Replacing these herbicides with glyphosate and glufosinate can reduce the occurrence of dissolved herbicide concentrations in runoff exceeding drinking water standards.

Conservation tillage can reduce soil loss; however, the residual herbicides normally used to control weeds are often detected in surface runoff at high levels, particularly if runoff-producing storms occur shortly after application. Therefore, we measured losses of alachlor, atrazine, linuron, and metribuzin from seven small (0.45-0.79-ha) watersheds for 9 yr (1993-2001) to investigate whether a reduced-input system for corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] production with light disking, cultivation, and half-rate herbicide applications could reduce losses compared with chisel and no-till. As a percentage of application, annual losses were highest for all herbicides for no-till and similar for chisel and reduced-input. Atrazine was the most frequently detected herbicide and yearly flow-weighted concentrations exceeded the drinking water standard of 3 μg L-1 in 20 out of 27 watershed years that it was applied. Averaged for 9 corn yr, yearly flow-weighted atrazine concentrations were 26.3, 9.6, and 8.3 μg L-1 for no-till, chisel, and reduced-input, respectively. Similarly, flow-weighted concentrations of alachlor exceeded the drinking water standard of 2 μg L-1 in 23 out of 54 application years and in all treatments. Thus, while banding and half-rate applications as part of a reduced-input management practice reduced herbicide loss, concentrations of some herbicides may still be a concern. For all watersheds, 60 to 99% of herbicide loss was due to the five largest transport events during the 9-yr period. Thus, regardless of tillage practice, a small number of runoff events, usually shortly after herbicide application, dominated herbicide transport.

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 × 12 m) were used for beef slurry application (9.1 Mg ha−1 wet weight); two plots had 61 × 12 m grassed filter areas below them, and two plots had 30 × 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.

Removal of corn (Zea mays L.) stover for biofuel production may affect crop yields by altering soil properties. A partial stover removal may be feasible, but information on appropriate rates of removal is unavailable. We assessed the short-term impacts of stover management on long-term no-till (NT) continuous corn grown on a Rayne silt loam (fine loamy, mixed, active, mesic Typic Hapludults) at Coshocton, Hoytville clay loam (fine, illitic, mesic Mollic Epiaqualfs) at Hoytville, and Celina silt loam (fine, mixed, active, mesic Aquic Hapludalfs) at South Charleston in Ohio, and predicted corn yield from soil properties using principal component analysis (PCA). The study was conducted in 2005 on the ongoing experiments started in May 2004 under 0 (T0), 25 (T25), 50 (T50), 75 (T75), 100 (T100), and 200 (T200)% of stover corresponding to 0, 1.25, 2.50, 3.75, 5.00, and 10.00 Mg ha-1 of stover, respectively. Stover removal promoted early emergence and rapid seedling growth (P < 0.01). Early-emerging plants grew taller than late-emerging plants up to about 50 d, and then the heights reversed at Coshocton and were comparable at other two sites. Stover management affected corn yield only at the Coshocton site where average grain and stover yields in the T200, T100, T75, and T50 (10.8 and 10.3 Mg ha-1) were higher than those in the T0 and T25 treatments (8.5 and 6.5 Mg ha-1) (P < 0.01), showing that stover removal at rates as low as 50% (2.5 Mg ha-1) decreased crop yields. Soil properties explained 71% of the variability in grain yield and 33% of the variability in stover yield for the Coshocton site. Seventeen months after the start of the experiment, effects of stover management on corn yield and soil properties were site-specific.

Phosphorus is an essential plant nutrient and critical to agricultural production, but it is also a problem when excessive amounts enter surface waters. Summer rotational grazing and winter feeding beef pasture systems at two fertility levels (56 and 28 kg available P ha-1) were studied to evaluate the P losses from these systems via surface runoff and subsurface flow using eight small (0.3-1.1 ha), instrumented watersheds and spring developments. Runoff events from a 14-yr period (1974-1988) were evaluated to determine the relationships between event size in mm, total dissolved reactive phosphorous (TDRP) concentration, and TDRP transport. Most of the TDRP transported was via surface runoff. There were strong correlations (r2 = 0.45-0.66) between TDRP transport and event size for all watersheds, but no significant (P = 0.05) correlations between TDRP concentration and event size. Flow-weighted average TDRP concentrations from the pasture watersheds for the 14-yr period ranged from 0.64 to 1.85 mg L-1 with a few individual event concentrations as high as 85.7 mg L-1. The highest concentrations were in events that occurred soon after P fertilizer application. Average seasonal flow-weighted TDRP concentrations for subsurface flow were <0.05 mg L-1. Applying P fertilizer to pastures in response to soil tests should keep TDRP concentrations in subsurface flow at environmentally acceptable levels. Management to reduce runoff and avoidance of P fertilizer application when runoff producing rainfall is anticipated in the next few days will help reduce the surface losses of P.

Corn (Zea mays L.) stover is a primary biofuel feedstock and its expanded use could help reduce reliance on fossil fuels and net CO2 emissions. Excessive stover removal may, however, negatively impact near-surface soil properties within a short period after removal. We assessed changes in soil crust strength, bulk density (rho(b)), and water content over a 1-yr period following a systematic removal or addition of stover from three no-till soils under corn in Ohio. Soils from ongoing experiments at the North Appalachian Experimental Watershed (NAEW), Western Agricultural Experiment Station (WAES), and Northwestern Agricultural Experiment Station (NWAES) of Ohio Agricultural Research and Development Center (OARDC) were studied. Six stover treatments of 0 (T0), 25 (T25), 50 (T50), 75 (T75), 100 (T100), and 200 (T200)% were imposed on 3 by 3 m plots corresponding to 0, 1.25, 2.50, 3.75, 5.00, and 10.00 Mg ha(-1) of stover, respectively. Cone index (CI), shear strength (SHEAR), rho(b), and volumetric water content (theta(v)) were measured monthly from June through December 2004 and in May 2005. Effects of stover removal on increasing CI and SHEAR were soil-specific. Stover removal consistently increased rho(b) and decreased theta(v) across soils (P < 0.01). Compared with the normal stover treatment (T100), doubling the amount of stover (T200) did not significantly affect soil properties except theta(v) where, after 1 yr, T200 increased theta(v) by 1.3 to 1.6 times compared with T100 across all sites (P < 0.05). After 1 yr, complete stover removal (T0) increased CI by 1.4 times and SHEAR by 1.3 times at NAEW compared with T100 and T75, but CI increases at other sites were nonsignificant. At NWAES, T0 increased SHEAR by 26% compared with T100 (P < 0.05). The T0 decreased theta(v) by two to four times except in winter months and increased rho(b) by about 10% compared with T100 (P < 0.05). In a short-term test, stover removal resulted in increased soil crust strength and reduced soil water content.

Soil strength influenced by management and soil properties controls plant growth, root development, and soil-moisture relations. The impact of textural and structural parameters on soil strength is moderated by soil organic C (SOC) concentration. Therefore, the objectives of this study were to assess differences in soil strength and SOC concentration in watersheds under long-term (>15 yr) management practices in the North Appalachian region on a predominantly Typic Hapludults on undulating slopes (>6% slope). Seven watersheds without field replication under moldboard plow (MP), chisel plow, disk with beef cattle manure (DiskM), no-till with beef cattle manure (NTm), no-till with no beef cattle manure (NTnm), pasture, and forest were studied. Cone index (CI), shear strength, bulk density (rho(b)), volumetric moisture content (theta(v)), and SOC concentration were determined at the summit, backslope, and footslope landscape positions at the 0- to 10-, 10- to 20-, and 20- to 30-cm depths. The SOC concentration was slightly higher at the footslope than at the summit position in the cultivated watersheds. The rho(b) was lower at the footslope than at the summit in NTm (1.22 vs. 1.42 Mg m(-3)) and chisel (1.34 vs. 1.47 Mg m(-3)) treatments. Forest had the lowest CI (0.19 MPa), shear strength (6.11 kPa), and rho(b) (0.93 Mg m(-3)) and the highest SOC concentration (62.7 g kg(-1)), whereas MP had the highest CI (0.67 MPa), shear strength (25.5 kPa), rho(b) (1.44 Mg m(-3)), and the lowest SOC concentration (13.6 g kg(-1)) in the 0- to 10-cm depth (P < 0.01). The SOC concentration in NTm was 1.7 times higher than that in NTnm, and both no-till treatments had lower rho(b) (<1.21 Mg m(-3)) than MP (1.44 Mg m(-3)) at 0- to 10-cm depth (P < 0.01). Manuring decreased both CI and shear strength, but increased SOC concentration. The rho(b), theta(v), and SOC concentration were potential predictors of CI; whereas rho(b) and SOC concentration were of shear strength (r2 > 0.42; P < 0.01). Results show that landscape positions had small effect, but management, particularly manuring, had large and significant effects on soil strength and SOC concentration.

Hydrologic data from agricultural watersheds are necessary to identify long-term trends and to develop and validate hydrologic and water quality models. These types of data have been collected for 70 yr at the North Appalachian Experimental Watershed (NAEW) near Coshocton, OH. The NAEW has 19 small (0.5–3.0-ha), single-land-use watersheds for which surface runoff data have been collected year round on an event basis for various time periods since 1939. There are six large (17–123-ha), mixed-use watersheds with perennial streams where flow is measured continuously. Hydrologic data have been collected from 11, 2.4-m-deep, 8.1-m2 surface area monolith lysimeters. Meteorological, land management, and soil property data are available. Water quality data have been collected from watersheds and lysimeters since the early 1970s. Collaborative research efforts utilizing this resource are encouraged; the NAEW web site (www.ars.usda.gov/mwa/coshocton; verified 19 Dec. 2009) has detailed information on the types of available data. Data are available through the authors.

Grazing is an important land use in the humid, eastern U.S. When the grass is dormant, late fall through early spring, the land is most vulnerable to the pressures of livestock. Runoff and sediment losses from a small pastured watershed (WS) in eastern Ohio have been studied for 20 years. In Period 1, a beef cow herd grazed it rotationally during the growing season for 12 years and was fed hay in this WS during the dormant season (high animal density with feeding). During the next 3 years of this study (Period 2), there was summer rotational grazing only. There was no animal occupancy on this WS during the last 5 years (Period 3). Annual runoff was more than 10% of precipitation during Period 1 (120 mm) and less than 2% during Periods 2 and 3 (14 and 6 mm, respectively). The decrease in annual sediment loss was even greater with the change in management, yielding 2259, 146, and 9 kg/ha for the three respective periods. Over 60% of the soil loss during Period 1 occurred during the dormant season. In response to weather inputs, there was considerable seasonal and annual variation in runoff and soil loss within management periods. Low amounts of runoff and erosion from three adjacent watersheds with summer-only grazing supported the conclusion that the increased runoff and erosion during Period 1 resulted from the non-rotational, winter feeding on pastures. When the management was changed, the impacts of the previous treatment were not long lasting, changing within a year.