121. Greenhouse Gas Mitigation Potential in U.S. Forestry and Agriculture

• Authors:
  • Andrasko, K.
  • DeAngelo, B.
  • Gillig, D.
  • McCarl, B.
  • Jones, K.
  • Depro, B.
  • Sommer, A. J.
  • Sohngen, B.
  • Murray, B. C.
• Year: 2005
• Summary: From executive summary: "This report evaluates the potential for additional carbon sequestration and GHG reductions in U.S. forestry and agriculture over the next several decades and beyond. It reports these reductions as changes from baseline trneds, starting in 2010 and projected out 100 years to 2110. The report employs the Forest and Agriculture Sector Optimization Model with Greenhouse Gases (FASOMGHG). FASOMGHG is a partial equilibrium economic model of the U.S. forest and agriculture sectors, with land use competition between them, and linkages to international trade. FASOMGHG includes most major GHG mitigation options in U.S. forestry and agriculture; accounts fo rchanges in CO2, GH4, and N2O from most activities; and tracks carbon sequestration and carbon losses over time. It also projects a dynamic baseline and reports all additional GHG mitigation as changes from that baseline. FASOMGHG tracks five forest product categories and over 2,000 production possibilities for field crops, livestock, and biofuels for private lands in the conterminous United States broken into 11 regions. Public lands are not included. FASOMGHG evaluates the joint economic and biophysical effects of a range of GHG mitigation scenarios, under which costs, mitigation levels, eligible activities, and GHG coverage may vary. The six scenarios evaluated in this report are constant GHG prices, rising GHG prices, fixed national mitigation levels, inclusion of selected mitigation activities only, incentive payments for CO2 only, and payments on a per-acre versus per-tonne basis. GHG mitigation incentives are estimated by dollars per tonne of CO2 equivalent ($/t CO2 Eq.) payments for four of the six scenarios above. The model and analysis cover the 100 years from 2010 to 2110, but three focus dates are highlighted: 2015, 2025, and 2055. FASOMGHG's standard GHG accounting and payment approach is a comprehensive, pay-as-you-go system, for all applicable GHGs and activities over time. The analysis reported here is unique from other studies conducted on forestry and agricultural mitigation options on a number of fronts. First, the range of covered activities across the sectors is wide. Most comparable studies look at just one of the sectors or at one or a small subset of activities within each secvtor, which this report examines a fairly comprehensive set of activites across the two sectos covering a vast majority of all GHG effects. Of particular note are the inclusions of biofuels and non-CO2 mitigation options in agriculture. Second, the intertemporal dynamics of the economic and biophysical systems within FASOMGHG allow for an accounting of mitigation over time and by region, and for quantification of leakage effects that other studies generally have not produced. And third, the inclusion of non-GHG co-effects allows insights into the multiple environmental and economic tradeoffs that pertain to GHG mitigation in these sectors.

122. The adoption and impact of management intensive rotational grazing (MIRG) on Connecticut dairy farms

• Authors:
  • Lang, G.
  • Foltz, J.
• Source: Renewable Agriculture and Food Systems
• Volume: 20
• Issue: 4
• Year: 2005
• Summary: Management intensive rotational grazing (MIRG) has garnered a great deal of interest in recent years as a method for returning profitability to Northeastern dairy farms. This work uses a random sample of Connecticut dairy farmers to estimate a binary choice adoption model and then cost, productivity, and profit functions that control for the adoption choice. MIRG adopters are shown to be more educated and have less rented agricultural land (a proxy for lack of access to land within a short distance of the barn). MIRG adoption had no significant effects on costs and productivity, nor did it lower profits, per cow. Evidence was found, however, to suggest that full adopters of the technology had more profitable farms than partial adopters. These results also show the importance of controlling for the different characteristics of adopters when evaluating the returns to animal grazing.

123. Soil organic carbon sequestration and agricultural greenhouse gas emissions in the southeastern USA

• Authors:
  • Franzluebbers, A. J.
• Source: Soil & Tillage Research
• Volume: 83
• Issue: 1
• Year: 2005
• Summary: Agriculture in the southeastern USA can be highly productive (i.e., high photosynthetic fixation of atmospheric CO2) due to warm-moist climatic conditions. However, its impacts on greenhouse gas emissions and mitigation potential have not been thoroughly characterized. This paper is a review and synthesis of literature pertaining to soil organic C (SOC) sequestration and greenhouse gas emissions from agricultural activities in the southeastern USA. Conservation tillage is an effective strategy to regain some of the SOC lost following decades, and in some areas centuries, of intensive soil tillage and erosion. With conventional tillage (CT) as a baseline, SOC sequestration with no tillage (NT) was 0.42 ± 0.46 Mg ha-1 year-1 (10 ± 5 years). Combining cover cropping with NT enhanced SOC sequestration (0.53 ± 0.45 Mg ha-1 year-1) compared with NT and no cover cropping (0.28 ± 0.44 Mg ha-1 year-1). By increasing cropping system complexity, SOC could be increased by 0.22 Mg ha-1 year-1, irrespective of tillage management. Taking into account an average C cost of producing and transporting N fertilizer, SOC sequestration could be optimized at 0.24 Mg ha-1 year-1 with application of 107 kg N ha-1 year-1 on N-responsive crops, irrespective of tillage management. In longer-term studies (5-21 years), poultry litter application led to SOC sequestration of 0.72 ± 0.67 Mg ha-1 year-1 (17 ± 15% of C applied). Land that was previously cropped and converted to forages sequestered SOC at a rate of 1.03 ± 0.90 Mg ha-1 year-1 (15 ± 17 years). Limited data suggest animal grazing increases SOC sequestration on upland pastures. By expanding research on SOC sequestration into more diverse pasture and manure application systems and gathering much needed data on methane and nitrous oxide fluxes under almost any agricultural operation in the region, a more complete analysis of greenhouse gas emissions and potential mitigation from agricultural management systems would be possible. This information will be necessary for developing appropriate technological and political solutions to increase agricultural sustainability and combat environmental degradation in the southeastern USA.

124. Physical indicators of sustainability - a farming systems approach for the small farmer in the rainfed vertisols of the western zone of Tamil Nadu.

• Authors:
  • Jayanthi, C.
  • Shekinah, D. E.
  • Sankaran, N.
• Source: Journal of Sustainable Agriculture
• Volume: 25
• Issue: 3
• Year: 2005
• Summary: In a small-scale resource-poor farm, modest increments in productivity are no longer sufficient to justify the investment of scarce resources. Integrated farming systems with multiple enterprises pave the way for realizing increased productivity, profitability and sustainability in small farms of the developing countries. A study conducted at Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India from July 2000 to March 2002 to optimize enterprise combination, increase employment and bring about maximum bioresource utilization and residue recycling for a 1-ha farm of the dryland tract of the western zone of Tamil Nadu compared four farming system combinations: FS 2 (crop+pigeon+goat+agroforestry+farm pond), FS 3 (crop+pigeon+buffalo+agroforestry+farm pond), and FS 4 (crop+pigeon+goat+buffalo+agroforestry+farm pond) with FS 1 (sorghum only) as the reference system. The results indicated the following: crop (0.80 ha) fertilized with buffalo manure produced on the farm, with pigeon (10 pairs on 0.01 ha), goat (5:1 female:male on 0.02 ha), buffalo (2 milking buffaloes+1 calf on 0.03 ha), agroforestry (0.10 ha) and farm pond (0.04 ha) was the profitable system enterprise that generated higher employment year-round. This system also facilitated the maximum recycling of resources and residues generated on the farm among the enterprises. The output and the waste of one enterprise served as input to another. The nutritive value of the system in terms of carbohydrate, protein and fat was also highest with this enterprise combination. Thus, FS 4 seems to be the best enterprise combination as revealed by the physical indicators. However, since the purchase and maintenance of buffalo enterprise involves higher costs, for farmers who have limited cash for investment, linkage of crop (0.80 ha) with pigeon (10 pairs on 0.01 ha), goat (5:1 female:male on 0.05 ha), agroforestry (0.10 ha) and farm pond (0.04 ha) is suggested as the alternative farming system for sustainability instead of conventional cropping alone.

125. Conservation of isolated Atlantic heathlands in the Mediterranean region: effects of land-use changes in the Montseny biosphere reserve (Spain)

• Authors:
  • Plaixats, J.
  • Bartolome, J.
  • Fanlo, R.
  • Boada, M.
• Source: Biological Conservation
• Volume: 122
• Issue: 1
• Year: 2005
• Summary: In the Mediterranean region, cycles of controlled burning combined with continuous grazing appear to have been an effective tool for maintaining isolated Calluna vulgaris heathlands in the form in which they occur in many places in the Atlantic region. Changes in land use and management of the mosaic of extensively exploited heathland and associated grassland over recent decades, such as bringing land into cultivation followed by its abandonment and the prohibition of fires has resulted in a process of transformation into new shrub communities with lower biodiversity. In the Mediterranean region, these changes are similar to those described in the Atlantic area, but encroachment occurs faster and could lead ultimately to afforestation by Mediterranean woodland. In a study area of 300 ha of heathland in the Spanish Mediterranean basin (specifically, in the Montseny Natural Park and Biosphere Reserve), comparison of present and former vegetation showed that shrub cover increased from 15% in 1967 to 32% in 2000. Broom (Cytisus scoparius) was the main invasive species in abandoned crop fields, whereas Mediterranean holm oak forest (Quercus ilex) increased by 18%. The surface area of fernlands doubled and C. vulgaris heathlands decreased from 35% to just 9% during the same period. Intermixed grasslands also decreased moderately and progressively from 4% to 3%. It seems probable that cycles of fires are more important in terms of shrub control and biodiversity conservation than continuous grazing alone, even at a high rate of stocking (four small ruminants per hectare per year). This encroachment process throws into relief the role that isolated habitats can play as a monitor of land use changes. (C) 2004 Elsevier Ltd. All rights reserved.

126. Response of organic and inorganic carbon and nitrogen to long-term grazing of the shortgrass steppe

• Authors:
  • LeCain, D. R.
  • Morgan, J. A.
  • Schuman, G. E.
  • Reeder, J. D.
• Source: Environmental Management
• Volume: 33
• Issue: 4
• Year: 2004
• Summary: We investigated the influence of long-term (56 years) grazing on organic and inorganic carbon (C) and nitrogen (N) contents of the plant-soil system (to 90 cm depth) in shortgrass steppe of northeastern Colorado. Grazing treatments included continuous season-long (May-October) grazing by yearling heifers at heavy (60-75% utilization) and light (20-35% utilization) stocking rates, and nongrazed exclosures. The heavy stocking rate resulted in a plant community that was dominated (75% of biomass production) by the C 4 grass blue grama (Bouteloua gracilis), whereas excluding livestock grazing increased the production of C 3 grasses and prickly pear cactus (Opuntia polycantha). Soil organic C (SOC) and organic N were not significantly different between the light grazing and nongrazed treatments, whereas the heavy grazing treatment was 7.5 Mg ha higher in SOC than the nongrazed treatment. Lower ratios of net mineralized N to total organic N in both grazed compared to nongrazed treatments suggest that long-term grazing decreased the readily mineralizable fraction of soil organic matter. Heavy grazing affected soil inorganic C (SIC) more than the SOC. The heavy grazing treatment was 23.8 Mg ha ˆ1 higher in total soil C (0-90 cm) than the nongrazed treatment, with 68% (16.3 Mg ha ˆ1) attributable to higher SIC, and 32% (7.5 Mg ha ˆ1) to higher SOC. These results emphasize the importance in semiarid and arid ecosystems of including inorganic C in assessments of the mass and distribution of plant-soil C and in evaluations of the impacts of grazing management on C sequestration.

127. Management to reduce nitrogen losses in animal production

• Authors:
  • Rotz, C. A.
• Source: Journal of Animal Science
• Volume: 82
• Issue: 13
• Year: 2004
• Summary: Reduction of nitrogen loss in animal production requires whole-farm management. Reduced loss from one farm component is easily negated in another if all components are not equally well managed. Animal excretion of manure N can be decreased by improving the balance of protein or amino acids fed to that required by individual animals or animal groups or by improving production efficiency. Management to increase milk, meat, or egg production normally improves efficiency by reducing the maintenance protein required per unit of production. Large losses of manure nitrogen occur through the ammonia and nitrous oxide that are emitted into the atmosphere and the nitrate leached into groundwater. Up to half of the excreted nitrogen is lost from the housing facility, but this loss can be decreased through frequentmanure removal and by avoiding deep litter systems and feedlots. Tech- niques such as acid treatment of manure, scrubbing of ventilation air, and floor designs for separating feces and urine substantially reduce ammonia emissions, but these practices are often impractical or uneconomical for general use. Manure storage units improve nutrient utilization by allowing better timing of nutrient application with crop needs. At least 70% of the nitrogen entering anaerobic lagoons is typically lost, but a less than 10% loss can be maintained using slurry storage with a natural crust or other cover, or by drying poultry manure to at least 50% dry matter. Irrigation and surface spreading of manure without soil incorporation often ensures the loss of all remaining nonorganic nitrogen (typically, 20 to 40% of remaining nitrogen). Rapid incorporation and shallow injection methods decrease this loss by at least 50%, and deep injection into the soil essentially eliminates this loss. For grazing animals, excessive loss can be avoided by not overstocking pastures and avoiding late fall and winter grazing. Reducing emissions between the animal and the soil can lead to greater leaching and denitrification losses from the soil if this additional nitrogen is not used properly. The use of a crop rotation that efficiently absorbs these nutrients and applying nitrogen near the time it is needed by crops reduce the potential for further loss. Maintaining the proper number of animals per unit of land available for manure application is always crucial for efficient recycling of nitrogen. Our understanding of nitrogen loss processes is improved through modeling, and computer models assist in the development of integrated systems for efficient and economical nitrogen use in animal production.

128. Soil carbon sequestration impacts on global climate change and food security

• Authors:
  • Lal, R.
• Source: Science
• Volume: 304
• Issue: 5677
• Year: 2004
• Summary: The carbon sink capacity of the world's agricultural and degraded soils is 50 to 66% of the historic carbon loss of 42 to 78 gigatons of carbon. The rate of soil organic carbon sequestration with adoption of recommended technologies depends on soil texture and structure, rainfall, temperature, farming system, and soil management. Strategies to increase the soil carbon pool include soil restoration and woodland regeneration, no-till farming, cover crops, nutrient management, manuring and sludge application, improved grazing, water conservation and harvesting, efficient irrigation, agroforestry practices, and growing energy crops on spare lands. An increase of 1 ton of soil carbon pool of degraded cropland soils may increase crop yield by 20 to 40 kilograms per hectare (kg/ha) for wheat, 10 to 20 kg/ha for maize, and 0.5 to 1 kg/ha for cowpeas. As well as enhancing food security, carbon sequestration has the potential to offset fossil fuel emissions by 0.4 to 1.2 gigatons of carbon per year, or 5 to 15% of the global fossil-fuel emissions.

129. Economics of Grazing or Haying Conservation Reserve Program Land

• Authors:
  • Diersen, M. A.
• Source: South Dakota State University Cooperative Extension Service Extension Extra
• Year: 2004
• Summary: This extension bulletins examines the economics of grazing or haying Conservation Reserve Program (CRP) land.

130. Six years of CO2 flux measurements for a moderately grazed mixed-grass prairie

• Authors:
  • Frank, A. B.
• Source: Environmental Management
• Volume: 33
• Issue: Supplement 1
• Year: 2004
• Summary: The large area occupied by temperate grassland ecosystems makes it important to determine their strength as a carbon sink. The Bowen ratio/energy balance (BREB) technique was used to determine CO 2 fluxes over a moderately grazed mixed-grass prairie at Mandan, North Dakota, USA, over a 6-year period from 1996 to 2001. Above-ground biomass and leaf area index (LAI) were measured about every 21 days throughout the growing period. Root biomass was determined to 1.1 m depth in mid-July each year. Peak above-ground biomass typically occurred between mid-July to early August and ranged from 782 kg/ha in 1998 to 2173 kg/ha in 1999. Maximum LAI ranged from 0.4 in 1998 to 0.9 in 1999. Root biomass ranged from 11.8 Mg/ha in 1997 to 17.4 Mg/ha in 1996. Maximum daily CO 2 fluxes generally coincided with periods of maximum LAI and above-ground green biomass. The average time period for CO 2 uptake was 5 May to 3 October. Annual CO 2 fluxes ranged from a low of 13 g CO 2/m 2 in 1998 to a high of 247 g CO 2/m 2 in 2001, nearly a 20-fold difference, and averaged 108 g CO 2/m 2. The cumulative annual flux over all 6 years was 646 g CO 2/m 2 or 176 g CO 2-C/m 2. These results indicate that the strength of the carbon sink for this moderately grazed prairie site is about 30 g CO 2-C/m 2/yr, which is quite small, but considering that the site was grazed and still remains a sink for carbon, it is significant.