- Authors:
- Manley, W. A.
- Hart, R. H.
- Manley, J. T.
- Reeder, J. D.
- Schuman, G. E.
- Source: Ecological Applications
- Volume: 9
- Issue: 1
- Year: 1999
- Summary: Rangeland grazing management strategies have been developed in an effort to sustain efficient use of forage resources by livestock. However, the effects of grazing on the redistribution and cycling of carbon (C) and nitrogen (N) within the plant-soil system are not well understood. We examined the plant-soil C and N balances of a mixed grass rangeland under three livestock stocking rates using an area that had not been grazed by domestic livestock for more than 40 years. We established nongrazed exclosures and pastures subjected to continuous season-long grazing at either a light stocking rate (20 steer-days/ha) or a heavy stocking rate (59 steer-days/ha, ~50% utilization of annual production). Twelve years of grazing under these stocking rates did not change the total masses of C and N in the plant-soil (0-60 cm) system but did change the distribution of C and N among the system components, primarily via a significant increase in the masses of C and N in the root zone (0-30 cm) of the soil profile. The mass of soil C (0-60 cm) under heavy grazing was comparable to that of the light grazing treatment. Grazing at the heavy stocking rate resulted in a decrease in peak standing crop (PSC) of aboveground live phytomass, an increase in blue grama (Bouteloua gracilis [H.B.K.] Lag. Ex Steud.), and a decrease in western wheatgrass (Pascopyrum smithii [Rydb.] A. Love) compared to the light grazing treatment. The dominant species under light grazing was western wheatgrass, whereas in the nongrazed exclosures, forbs were dominant and appeared to have increased at the expense of western wheatgrass. The observed increase of soil C and N in the surface soil where roots dominate indicates a greater opportunity for nutrient availability and cycling, and hence enhanced grazing quality.
- Authors:
- Source: The American Economic Review
- Volume: 89
- Issue: 4
- Year: 1999
- Summary: selections from paper: "I develop and demonstrate a method by which the costs of carbon sequestration can be estimated on the basis of evidence from landowners' behavior when confronted with the opportunity costs of alternative land uses...develop an econometric model of land use...simulation model of carbon sequestration...derive...marginal cost results
- Authors:
- Year: 1999
- Summary: This report has two objectives. First, it presents the U.S. Environmental Protection Agency’s (EPA’s) baseline forecast of methane emissions from the major anthropogenic sources in the U.S., and EPA’s cost estimates of reducing these emissions. Emission estimates are given for 1990 through 1997 with projections for 2000 to 2020. The cost analysis is for 2000, 2010, and 2020. Second, this report provides a transparent methodology for the calculation of emission estimates and reduction costs, thereby enabling analysts to replicate these results or use the approaches described herein to conduct similar analyses for other countries. Chapter 5: "EPA estimates 1997 U.S. methane emissions from livestock manure management at 17.0 MMTCE (3.0 Tg), which accounts for ten percent of total 1997 U.S. methane emissions (EPA, 1999). The majority of methane emissions come from large swine (hog) and dairy farms that manage manure as a liquid. As shown below in Exhibit 5-1, EPA expects U.S. methane emissions from livestock manure to grow by over 25 percent from 2000 to 2020, from 18.4 to 26.4 MMTCE (3.2 to 4.6 Tg). This increase in methane emissions is primarily due to the increasing use of liquid and slurry manure management systems which generate methane. This use is associated with the trend toward larger farms with higher, more concentrated numbers of animals." - from summary
- Authors:
- Cole, C. V.
- Follett,R. F.
- Kimble, J.
- Lal, R.
- Source: Journal of Soil and Water Conservation
- Volume: 54
- Issue: 1
- Year: 1999
- Summary: The effects of human activities on atmospheric concentrations of carbon dioxide (CO2) and other greenhouse gases (GHGs) are under intensive study in the United States and worldwide. Since conversion to cropland during the 17th and 18th centuries, the vegetation and soils of the U.S. forests, grasslands, and wetlands have undergone extensive change. Clearing, tilling, and draining of these soils for long-term cropland use released large amounts of CO2, a GHG, to the atmosphere from the soils' fertile soil organic matter (SOM). The SOM in topsoil often was depleted by up to half of its soil organic carbon (SOC) (Cambardella and Elliott 1992). Now, improved farming technologies, increased farmland productivity, and government programs to return highly erodible lands to permanent vegetation are producing unanticipated benefits by letting soils become major sinks for atmospheric CO2 that is stored in them as increasing levels of SOC.
- Authors:
- Cole, C. V.
- Follett, R. F.
- Kimble, J. M.
- Lal, R.
- Year: 1999
- Summary: from exec. summary: "This report...assesses the potential of U.S. cropland to sequester carbon (C). It concludes that properly applied soil restorative processes and best management practices (BMPs) can mitigate the greenhouse effect both by decreasing the emissions of greenhouse gases (GHGs) from U.S. agricultural activities and by making U.S. cropland a major sink for C sequestration. Worldwide soil restoration and adoption of BMPs has a potential to mitigate effectively a large proportion of the annual increase in atmospheric concentration of CO2."
- Authors:
- Peters, M.
- House, R.
- Lewandrowski, J.
- McDowell, H.
- Source: Agricultural Outlook
- Year: 1999
- Authors:
- Source: Science
- Volume: 284
- Issue: 5423
- Year: 1999
- Summary: Maintaining and increasing soil organic matter (SOM) adds to soil fertility, water retention, and crop production. Recently, many soil scientists have suggested that the sequestration of atmospheric carbon dioxide in SOM could also contribute significantly to attempts to adhere to the Kyoto Protocol. Conversion of large areas of cropland to conservation tillage, including no-till practices, during the next 30 years could sequester all the CO2 emitted from agricultural activities and up to 1% of today's fossil fuel emissions in the United States. Similarly, alternative management of agricultural soils in Europe could potentially provide a sink for about 0.8% of the world's current CO2 release from fossil fuel combustion. Beyond conservation tillage, however, many of the techniques recommended to increase carbon sequestration in soils contain hidden carbon “costs” in terms of greater emissions of CO2 into the atmosphere.
- Authors:
- Martínez, J.
- Haines, T. K.
- Cleaves, D. A.
- Source: USDA Forest Service General Technical Report PSW-GTR-173
- Year: 1999
- Summary: The results of a survey from 1985 to 1994 of the USDA Forest Service's National Forest System prescribed burning activity and costs are examined. Fuels management officers from 95 National Forests reported costs and acreage burned for 4 types of prescribed fire, including slash reduction, management-ignited fires, prescribed natural fires, and brush, grass, and rangeland burns, and rated the relative importance of 9 resource enhancement targets and 12 factors influencing burning costs. Substantial differences were found in per acre costs and cost variability by burn type, National Forest Regions, and resource target mix. Planning costs were estimated to be about 25 percent of total costs in most regions. Unit size, labor availability, escape fire safeguards, and environmental restrictions were the most important cost influences, but these varied by region. Data limitations suggest the need for a uniform, comprehensive system of data collection on prescribed burning activity and costs.
- Authors:
- Paul, E. A.
- Huggins, D. R.
- Dick, W. A.
- Bundy, L. G.
- Blevins, R. L.
- Christenson, D. R.
- Collins, H. P.
- Source: Soil Science Society of America Journal
- Volume: 63
- Issue: 3
- Year: 1999
- Summary: We used natural 13C abundance in soils to calculate the fate of C4-C inputs in fields cropped to continuous corn (Zea mays L.). Soil samples were collected from eight cultivated and six adjacent, noncultivated sites of the Corn Belt region of the central USA. The amount of organic C in cultivated soils declined an average of 68%, compared with adjacent, noncultivated sites. The {delta} 13C of cultivated soil profiles that had been under continuous corn for 8 to 35 yr increased in all depth increments above that of the noncultivated profiles. The percentage of soil organic C (SOC) derived from corn residues and roots ranged from 22 to 40% of the total C. The proportion of corn-derived C, as determined by this technique, decreased with soil depth and was minimal in the 50- to 100-cm depth increments of fine-textured soils. The mean residence time of the non-corn C (C3) ranged from 36 to 108 yr at the surface, and up to 769 yr at the subsoil depth. The longer turnover times were associated with soils high in clay. Prairie-derived soils have a higher potential to sequester C than those derived from forests. The significant loss of total C at all sites and the slow turnover times of the incorporated C lead us to conclude that there is a substantial potential for soils to serve as a C sink and as a significant nutrient reserve in sustainable agriculture.
