Explore the vast range of titles available.

Contrary to earlier studies, this study suggests that even one year of tillage within a long-term no-till agroecosystem adversely affected the soil quality, with possible negative impact on crop yields. Worldwide interest in conservation tillage is increasing, because conventional tillage adversely impacts the long-term quality of the soil and its vulnerability to erosion. No-till agriculture minimizes adverse impacts of an intensive arable land use. In some cases, occasional tillage is used as a means of weed or pathogen control. Therefore, this study was conducted in eastern Ohio to examine soil quality as affected by occasional tillage, i.e. disk plowed every 3–4 years, within a long-term no-till agroecosystem. The study compared the soil characteristics between two fields, both under corn ( Zea mays L.) at the time of the study. Soil properties were studied for three depths of 0–6, 6–12, and 12–18 cm. Compared with the continuous no-till field, the field under occasional tillage had significantly higher bulk density of 1.45 versus 1.31 g cm −3 , and somewhat higher soil penetration resistance of 1.77 versus 1.56 MPa. Also, compared with the no-till field, the field under occasional tillage had significantly lower water stable aggregate of 475 versus 834 g kg −1 , mean weight diameter of 1.4 versus 3.4 mm, field moisture capacity of 293 versus 360 g kg −1 , equilibrium infiltration rate of 2.0 versus 6.7 mm min −1 , and cumulative infiltration of 353.4 versus 1,211.8 mm. The field under occasional tillage had somewhat lower soil organic carbon of 16.0 versus 19.2 g kg −1 , soil water sorptivity of 16.3 versus 36.5 mm min −0.5 , and transmissivity of 2.1 versus 4.9 mm min −1 . The occasional tillage had no effect on the soil shear strength. In general, the effect of tillage on soil properties decreased with increase in soil depth. Also corn yields were compared between the two agroecosystems. Compared with the no-till field, the field under occasional tillage had significantly lower grain moisture content of 22.4 versus 28.2%, and somewhat lower wet stover biomass of 14.6 versus 20.2 Mg ha −1 , wet corn ear yield of 10.0 versus 11.4 Mg ha −1 , and dry grain yield of 8.2 versus 9.4 Mg ha −1 . As contrasted with earlier studies which were conducted under controlled research plots, this study was conducted under on-farm conditions.

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.

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.

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.

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.

Aggregate properties determine the macroscale structural condition of the soil. Understanding of impacts of no‐till and traditional agricultural practices on the mechanical properties of aggregates is fundamental to soil management. This study assessed the tensile strength (TS), bulk density (ρagg), soil moisture retention (SMR), and soil organic C (SOC) concentration of soil aggregates and determined the interrelationships among aggregate properties under long‐term moldboard plow (MP), chisel plow (CP), disk with beef cattle manure (DM), no‐till with beef cattle manure (NTM), no‐till without beef cattle manure (NT), pasture, and forest systems in the North Appalachian region. Properties were determined on 1‐ to 8‐mm aggregates from 0‐ to 30‐cm soil depth. The TS and SMR (0 to −333 kPa) in NTM were higher than those in MP and CP (P < 0.01). The SOC concentration for NTM was higher than that for MP, CP, and NT (P < 0.01). The ρagg was 1.35 Mg m−3 in NTM and approximately 1.61 Mg m−3 in MP and CP (P < 0.01). Manuring had a positive and excessive tillage negative impact on aggregate properties. Aggregates from forest had the lowest TS (63 kPa) and ρagg (0.99 Mg m−3) and the highest SOC concentration (70 g kg−1), whereas the MP and CP had the highest TS (approximately 358 kPa) and the lowest SOC concentration (14 g kg−1) in 0‐ to 10‐cm depth (P < 0.01). Mean ρagg was significantly higher than the density of bulk soil (ρb). The log‐transformed TS (LogTS) increased with increasing ρagg and decreased with increasing aggregate size and SOC. Size, SOC concentration, and ρagg explained 84% of the variability of LogTS. Long‐term (>35 yr) no‐till combined with manuring improved the aggregate properties contrasting with conventionally cultivated systems.

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.

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.

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-1. Ground 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-1. Both 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.

High rates of N fertilizer in the production of continuous corn (Zea mays L.) have resulted in excessive nitrate N (NO3‐N) leaching, with concentrations in ground water frequently exceeding the maximum contaminant level (MCL) of 10 mg/L. This study was conducted to determine whether NO3‐N leaching would be reduced by allowing for a legume N credit for soybean [Glycine max (L.) Merr.], and applying less N fertilizer to corn in a corn‐soybean rotation than would be applied to continuous corn. A rye (Secale cereale L.) winter cover crop was used following soybean. In the spring of each corn year, 140 kg N/ha as NH4NO3 was surface applied to two large, undisturbed monolith lysimeters (8.1 m2 surface area, 2.4 m deep), and 196 kg N/ha was applied to two other lysimeters. Prior to 6 yr of this treatment, there was a 6 yr period during which lysimeters received 224 kg N/ha in the spring of the corn year. The highest NO3‐N concentrations and the most transport occurred during the winter/spring soil moisture recharge period (November through April). Concentrations of NO3‐N in the percolate from all four lysimeters were similar, with a 6‐yr, flow‐weighted average of 9.9 ± 2.5 mg/L. Although reducing N fertilizer inputs in a corn‐soybean rotation to allow for a legume N credit may lower N leaching amounts and concentrations, the NO3‐N MCL may still be exceeded. For a given year, weather can impact percolation and leaching more than the current crop.