• Authors:
    • Harben, R.
    • Beyer, J.
    • Dusault, A.
    • Fry, R.
    • Shrestha, A.
    • Klonsky, K. M.
    • Mitchell, J. P.
  • Source: Australian Journal of Experimental Agriculture
  • Volume: 47
  • Issue: 12
  • Year: 2007
  • Summary: While there have been several similarities between the development of cropping systems in Australia and California ( including climate, the need for irrigation and very diverse, highly specialised crop rotations), the historical patterns of conservation tillage development in the two regions have been quite different. Current estimates indicate that conservation tillage ( CT) practices are used on less than 2% of annual crop acreage in California's Central Valley. Tillage management systems have changed relatively little since irrigation and cropping intensification began throughout this region, more than 60 years ago. The University of California ( UC) and United States Department of Agriculture ( USDA) Natural Resource Conservation Service ( NRCS) CT Workgroup is a diverse group of UC, NRCS, farmer, private sector, environmental group and other public agency people. It has provided wide- ranging services aimed at developing information on reduced tillage alternatives for California's production valleys. In a short span of 7 years, the CT Workgroup has grown to over 1000 members and has conducted over 60 demonstration evaluations of CT systems. While CT is still quite new in California, a growing number of farmers has become increasingly interested in it, for both economic and environmental reasons. They are now pursuing a wide range of activities and approaches aimed at developing sustainable CT systems. As successful CT systems continue to be demonstrated, the rate of adoption is expected to increase.
  • Authors:
    • Wright, J.
    • Herrick, J.
    • Fredrickson, E.
    • Bestelmeyer, B.
    • Brown, J.
    • Skaggs, R.
    • Peters, D. P. C.
    • Havstad, K. M.
  • Source: Ecological Economics
  • Volume: 64
  • Issue: 2
  • Year: 2007
  • Summary: The over 300 million ha of public and private rangelands in the United States are characterized by low and variable precipitation, nutrient-poor soils, and high spatial and temporal variability in plant production. This land type has provided a variety of goods and services, with the provisioning of food and fiber dominating through much of the 20th century. More recently, food production from a rangeland-based livestock industry is often pressured for a variety of reasons, including poor economic returns, increased regulations, an aging rural population, and increasingly diverse interests of land owners. A shift to other provisioning, regulating, cultural, and supporting services is occurring with important implications for carbon sequestration, biodiversity, and conservation incentives. There are numerous goods and services possible from rangelands that can supply societal demands such as clean water and a safe food supply. The use of ecologically-based principles of land management remains at the core of the ability of private land owners and public land managers to provide these existing and emerging services. We suggest that expectations need to be based on a thorough understanding of the diverse potentials of these lands and their inherent limits. A critical provisioning service to rangelands will be management practices that either maintain ecological functions or that restore functions to systems that have been substantially degraded over past decades. With proper incentives and economic benefits, rangelands, in the U.S. or globally, can be expected to provide these historical and more unique goods and services in a sustainable fashion, albeit in different proportions than in the past.
  • Authors:
    • Keita, M.
    • Kodio, A.
    • Nelson, R.
    • Jones, J. W.
    • Stöckle, C. O.
    • Badini, O.
  • Source: Agricultural Systems
  • Volume: 94
  • Issue: 1
  • Year: 2007
  • Summary: In the Sahel region of West Africa, the traditional organization of the population and the grazing land avoided overexploitation of pastures. Since independence in the 1960s, grazing lands have been opened to all without specific guidance, and the vulnerability of the pastures to degradation has increased. Rotational grazing is postulated as a possible solution to provide higher pasture productivity, higher animal loads per unit land, and perhaps improved soil carbon storage. The objective of this study was to conduct a simulation-based assessment of the impact of rotational grazing management on pasture biomass production, grazing efficiency, animal grazing requirement satisfaction, and soil carbon storage in the Madiama Commune, Mali. The results showed that grazing intensity is the primary factor influencing the productivity of annual pastures and their capacity to provide for animal grazing requirements. Rotating the animals in paddocks is a positive practice for pasture protection that showed advantage as the grazing pressure increased. Increasing the size of the reserve biomass not available for grazing, which triggers the decision of taking the animals off the field, provided better pasture protection but reduced animal grazing requirements satisfaction. In terms of soil carbon storage, all management scenarios led to reduction of soil carbon at the end of the 50-year simulation periods, ranging between 4% and 5% of the initial storage. The differences in reduction as a function of grazing intensity were of no practical significance in these soils with very low organic matter content, mostly resistant to decomposition.
  • Authors:
    • Azarnivand, H.
    • Jafari, M.
    • Sharifani, F.
    • Abbasi, H.
    • Sori, M.
  • Source: Iranian Journal of Range and Desert Research
  • Volume: 13
  • Issue: 4
  • Year: 2007
  • Summary: The effects of plant growth on soil quality in the Sagzi plain of Isfahan (Iran) were determined to evaluate the influence of agriculture on the desertification processes in dry lands. Inappropriate crop management significantly affected soil and water salinization which is one of the important processes of desertification. To determine if agriculture is a positive or negative factor for the reclamation of saline soils, improved and degraded factors of desertification in Sagzi plain of Isfahan were considered. Medicago, wheat and barley were evaluated to determine which crop is more effective for soil reclamation. Wheat and barley were selected and compared with derelict land, which was and independent variable in this study. The soils considered were cultivated with these products successively for at least 5 years. Soil samples were then obtained at different depths (0-3, 30-60, 60-90, 90-120, 120-150 cm) and were analysed for CaCO 3, electrical conductivity, organic matter, K +, Mg +, Ca 2+, Na +, CaSO 4, Cl -, sodium adsorption ratio, HCO 3- and SO 4-. Variance analysis showed significant difference between treatments at different depths and that among the three crops, wheat cropping is the best for soil reclamation.
  • Authors:
    • An, M.
    • Cheema, Z. A.
    • Iqbal, J.
  • Source: Plant and Soil
  • Volume: 300
  • Issue: 1/2
  • Year: 2007
  • Summary: A 2-year field investigation was carried out during 2003-2004 to determine the effectiveness of intercropping single and double rows of sorghum, soybean and sesame in a cotton crop on the suppression of purple nutsedge ( Cyperus rotundus L.). Results revealed that all three intercrops were effective in inhibiting purple nutsedge density (70-96%) and dry matter production (71-97%) during both years of experimentation. Control in the second year was more effective than in the first year. The seed cotton yield was also depressed by the intercrops but its suppression (8-23%) was far less severe than that of purple nutsedge and its loss was compensated by greater total economic returns. Intercropping of sorghum and sesame produced greater than 20% net benefits (up to 60%) in comparison with the control (cotton alone). Soybean intercropping produced comparable net benefits (95-103%). Sesame two rows intercrop treatment appeared the most profitable with net benefit of 51-59% with good purple nutsedge control (73-92% density suppression, 77-95% dry weight suppression) during both years of experimentation.
  • Authors:
    • Kahlown, M. A.
    • Azam, M.
    • Kemper, W. D.
  • Source: Journal of Soil and Water Conservation
  • Volume: 61
  • Issue: 1
  • Year: 2006
  • Summary: Conventional management practices for the rice-wheat rotation in Pakistan's Punjab have failed to improve crop yield, increase water and fertilizer use efficiencies, and decrease production costs enough to meet an ever-increasing food demand. New technologies such as no-till, laser leveling, and bed and furrow irrigation are being rapidly adopted by the farming community, but without adequate scientific information. Therefore, those practices were evaluated on 71 farms within four representative sites. Land preparation/sowing costs, water savings, use of fertilizers, soil salinity, and crop yield were evaluated. Land preparation and sowing cost on no-till fields was significantly less than on tilled fields. Highest yields were obtained on laser-leveled fields, followed by no-till, bed and furrow fields. Water and nitrogen use efficiencies were much higher on fields with bed and furrow irrigation as compared to the conventional fields. Although the new technologies were economically feasible, we conclude that no-till was the best option for the farmers.
  • Authors:
    • Kimble, J. M.
    • McCarty, G. W.
    • Follett, R. F.
    • Reeves, J. B.
  • Source: Communications in Soil Science and Plant Analysis
  • Volume: 37
  • Issue: 15-20
  • Year: 2006
  • Summary: The objective of this study was to compare mid-infrared (MIR) an near-infrared (NIR) spectroscopy (MIRS and NIRS, respectively) not only to measure soil carbon content, but also to measure key soil organic C (SOC) fractions and the delta13C in a highly diverse set of soils while also assessing the feasibility of establishing regional diffuse reflectance calibrations for these fractions. Two hundred and thirty-seven soil samples were collected from 14 sites in 10 western states (CO, IA, MN, MO, MT, ND, NE, NM, OK, TX). Two subsets of these were examined for a variety of C measures by conventional assays and NIRS and MIRS. Biomass C and N, soil inorganic C (SIC), SOC, total C, identifiable plant material (IPM) (20x magnifying glass), the ratio of SOC to the silt+clay content, and total N were available for 185 samples. Mineral-associated C fraction, delta13C of the mineral associated C, delta13C of SOC, percentage C in the mineral-associated C fraction, particulate organic matter, and percentage C in the particulate organic matter were available for 114 samples. NIR spectra (64 co-added scans) from 400 to 2498 nm (10-nm resolution with data collected every 2 nm) were obtained using a rotating sample cup and an NIRSystems model 6500 scanning monochromator. MIR diffuse reflectance spectra from 4000 to 400 cm-1 (2500 to 25,000 nm) were obtained on non-KBr diluted samples using a custom-made sample transport and a Digilab FTS-60 Fourier transform spectrometer (4-cm-1 resolution with 64 co-added scans). Partial least squares regression was used with a one-out cross validation to develop calibrations for the various analytes using NIR and MIR spectra. Results demonstrated that accurate calibrations for a wide variety of soil C measures, including measures of delta13C, are feasible using MIR spectra. Similar efforts using NIR spectra indicated that although NIR spectrometers may be capable of scanning larger amounts of samples, the results are generally not as good as achieved using MIR spectra.
  • Authors:
    • Deregibus, V. A.
    • Bartoloni, N.
    • Rodriguez, A. M.
    • Jacobo, E. J.
  • Source: Rangeland Ecology & Management
  • Volume: 59
  • Issue: 3
  • Year: 2006
  • Summary: We evaluated the adequacy of rotational grazing to improve rangeland condition in the Flooding Pampa region, eastern Argentina, comparing the floristic composition dynamic of the 2 main plant communities under rotational and continuous grazing over a study period of 4 years (1993-1996). The experiment was conducted in commercial farms located in 4 sites of the Flooding Pampa region. In each site, a couple of farms, one managed under rotational grazing (implemented in 1989) and an adjacent one managed under continuous grazing at a similar stocking rate (1 AU(.)ha(-1)), constituted the replications of the experiment. Basal cover of species, litter, and bare soil were monitored in midslope and lowland grassland communities on each farm. Total plant basal cover in midslope and in lowland communities remained unchanged over the whole experimental period under both grazing methods. Under rotational grazing, litter cover was higher in both communities while the amount of bare soil showed a significant reduction in lowlands and a tendency to be lower in midslope. Basal cover of legumes, C-3 annual and C-3 perennial grasses was higher, while cover of C-4 prostrate grasses was lower under rotational grazing in the midslope community. In the lowland community, rotational grazing effects were evident only in the drier years, when higher cover of hydrophytic grasses and legumes and lower cover of forbs occurred. Plant species diversity did not change in response to grazing. In conclusion, rotational grazing promoted functional groups composed of high forage value species and reduced bare soil through the accumulation of litter. These changes indicate an improvement in rangeland condition and in carrying capacity. As the stocking rate was approximately 60% higher than the average stocking rate of the Flooding Pampa region, we believe that productivity and sustainability may be compatible by replacing continuous with rotational grazing.
  • Authors:
    • Perez, A.
    • Ali, M.
    • Pollack, S.
    • Lucier, G.
  • Year: 2006
  • Summary: The U.S. fruit and vegetable industry accounts for nearly a third of U.S. crop cash receipts and a fifth of U.S. agricultural exports. A variety of challenges face this complex and diverse industry in both domestic and international markets, ranging from immigration reform and its effect on labor availability to international competitiveness. The national debate on diet and health frequently focuses on the nutritional role of fruit and vegetables, and a continued emphasis on the benefits of eating produce may provide opportunities to the industry. In the domestic market, Americans are eating more fruit and vegetables than they did 20 years ago, but consumption remains below recommended levels. In terms of per capita consumption expressed on a fresh-weight basis, the top five vegetables are potatoes, tomatoes, lettuce, sweet corn, and onions while the top five fruit include oranges, grapes (including wine grapes), apples, bananas, and pineapples. The industry also faces a variety of trade-related issues, including competition with imports. During 2002-04, imports accounted for 21 percent of domestic consumption of all fresh and processed fruit and vegetables, up from 16 percent during 1992-94.
  • Authors:
    • Young, G.
    • Stuth, J.
    • Rauzi, S.
    • Peterson, T.
    • Pawar, R.
    • Kobos, P.
    • Mankin, C.
    • Leppin, D.
    • Lee, R.
    • Kim, E.
    • Hughes, R.
    • Guthrie, G.
    • Cappa, J.
    • Brown, J.
    • Biediger, B.
    • Allis, R.
    • McPherson, B.
  • Year: 2006
  • Summary: The Southwest Partnership on Carbon Sequestration completed its Phase I program in December 2005. The main objective of the Southwest Partnership Phase I project was to evaluate and demonstrate the means for achieving an 18% reduction in carbon intensity by 2012. Many other goals were accomplished on the way to this objective, including (1) analysis of CO2 storage options in the region, including characterization of storage capacities and transportation options, (2) analysis and summary of CO2 sources, (3) analysis and summary of CO2 separation and capture technologies employed in the region, (4) evaluation and ranking of the most appropriate sequestration technologies for capture and storage of CO2 in the Southwest Region, (5) dissemination of existing regulatory/permitting requirements, and (6) assessing and initiating public knowledge and acceptance of possible sequestration approaches. Results of the Southwest Partnership's Phase I evaluation suggested that the most convenient and practical "first opportunities" for sequestration would lie along existing CO2 pipelines in the region. Action plans for six Phase II validation tests in the region were developed, with a portfolio that includes four geologic pilot tests distributed among Utah, New Mexico, and Texas. The Partnership will also conduct a regional terrestrial sequestration pilot program focusing on improved terrestrial MMV methods and reporting approaches specific for the Southwest region. The sixth and final validation test consists of a local-scale terrestrial pilot involving restoration of riparian lands for sequestration purposes. The validation test will use desalinated waters produced from one of the geologic pilot tests. The Southwest Regional Partnership comprises a large, diverse group of expert organizations and individuals specializing in carbon sequestration science and engineering, as well as public policy and outreach. These partners include 21 state government agencies and universities, five major electric utility companies, seven oil, gas and coal companies, three federal agencies, the Navajo Nation, several NGOs, and the Western Governors Association. This group is continuing its work in the Phase II Validation Program, slated to conclude in 2009.