Author
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Owens, Lloyd |
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Hothem, Daniel |
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Submitted to: Eastern Native Grass Symposium
Publication Type: Proceedings Publication Acceptance Date: 5/1/2000 Publication Date: N/A Citation: N/A Interpretive Summary: Organic matter has long been considered important in agricultural soils. But with global change issues and the possible role of CO2 in those changes, it is important to evaluate the potential practices to mitigate CO2 emissions through carbon storage in soils. Many cropping practices need to be studied, including grasslands. At the North Appalachian Experimental Watershed near Coshocton, OH different grazing/grassland management practices have been studied for over 20 years. Soil samples from these systems were taken and archived over much of the life of these studies. Total carbon concentrations were measured in the soil profiles and the amount of total carbon was assessed. Beef cattle grazed pastures on unglaciated, silt loam soils with continuous grazing, rotational grazing with medium amounts of nitrogen fertilizer being applied, and rotational grazing with high amounts of nitrogen fertilizer. Total carbon concentrations were found to be as high as 2.5% in the 0-15 cm (0-6 in) layer and 5.0% in the 0-2.5 cm (0-1 in) layer. Total amounts of carbon in pasture soils ranged from 50-75 Mg/ha (22-33 tons/acre) for the 1-60 cm (0-24 in) depth and tended to be slightly higher with higher fertility. No-till practices have been shown to store more carbon that cultivation practices, which often have a net release of soil carbon. Pastures had greater carbon concentrations and carbon amounts than no-till corn/soybean-rye on similar soils. Such information strengthens the use of grasses as an option for land use, land reclamation, etc. This information is useful for farmers, land use planners, and consultants. Technical Abstract: To evaluate the potential for agricultural practices to mitigate CO2 emissions through C storage, many cropping practices need to be studied, including grasslands. At the North Appalachian Experimental Watershed near Coshocton, OH different grazing/grassland management practices have been studied for over 20 years. With archived soil samples from these areas, total carbon (TC) concentrations and amounts are being assessed. Management systems from which soils were sampled include: A.) continuous (non-rotational) grazing on unimproved pasture (28 ha); B.) four orchardgrass (Dactylis glomerata L.)/Kentucky bluegrass (Poa pratensis L.) paddocks (17 ha) for summer rotational grazing with 56 kg N/ha annually supplied for 5 years followed with 11 years of annual applications of 162 kg N/ha; C.) four orchardgrass paddocks (14 ha) for rotational summer grazing and 224 kg N/ha was annually applied for 5 years, followed by 10 years where the N source was from alfalfa (Medicago sativa L.) that had been interseeded into the orchardgrass; and D.) four tall fescue (Festuca arundinacea Schreb.) paddocks (10 ha) for winter grazing and feeding of the hay made during the summer; this area had the same N management as system C. TC contents were greatest for the summer grazed, fertilized pastures, ranging from 1.56 and 2.02% in 1975 to 2.22 and 2.37% in 1998 in the 0-15 cm layers for systems B and C, respectively. Systems A and D had similar TC contents, ranging from 1.30 and 1.37% to 1.88 and 1.81%, respectively. Amounts of TC in the 0-15 cm layer showed a similar pattern, with 1998 values of 34.8 and 36.0 Mg/ha for systems B and C, respectively. For comparison, a 12-year no-till corn/soybean rotation had 24.8 Mg/ha of TC. Soils under grasslands may store more C than soils with no-till. |
