• Authors:
    • WCI
  • Volume: 2010
  • Year: 2010
  • Summary: Welcome to the Western Climate Initiative (WCI). The WCI is a collaboration of independent jurisdictions working together to identify, evaluate, and implement emissions trading policies to tackle climate change at a regional level. This is a comprehensive effort to reduce greenhouse gas pollution, spur investment in clean-energy technologies that create green jobs and reduce dependence on imported oil.
  • Authors:
    • Stevens, W. E.
    • Scharf, P. C.
    • Kitchen, N. R.
    • Williams, J. D.
  • Source: Precision Agriculture
  • Volume: 11
  • Issue: 3
  • Year: 2010
  • Summary: Precise management of nitrogen (N) using canopy color in aerial imagery of corn (Zea mays L.) has been proposed as a strategy on which to base the rate of N fertilizer. The objective of this study was to evaluate the relationship between canopy color and yield response to N at the field scale. Six N response trials were conducted in 2000 and 2001 in fields with alluvial, claypan and deep loess soil types. Aerial images were taken with a 35-mm slide film from C1100 m at the mid- and late-vegetative corn growth stages and processed to extract green and red digital values. Color values of the control N (0 kg N ha-1) and sufficient N (280 kg N ha-1 applied at planting) treatments were used to calculate the relative ratio of unfertilized to fertilized and relative difference color values. Other N fertilizer treatments included side-dressed applications in increments of 56 kg N ha-1. The economic optimal N rate was weakly related (R2<= 0.34) or not related to the color indices at both growth stages. For many sites, delta yield (the increase in yield between control N and sufficient N treatments) was related to the color indices (R2<= 0.67) at the late vegetative growth stage; the best relationship was with green relative difference. The results indicate the potential for color indices from aerial photographs to be used for predicting delta yield from which a site-specific N rate could be determined.
  • Authors:
    • Hyman, J. M.
    • Lichau, A.
    • Richardson, A.
    • Kerchner, C. D.
    • Winsten, J. R.
  • Source: Journal of Dairy Science
  • Volume: 93
  • Issue: 4
  • Year: 2010
  • Summary: This paper provides a summary of results from a recent survey of 987 dairy farmers in 4 northeastern US states. The survey results provide descriptive characteristics of the current state of dairy farming in the region, as well as farmer satisfaction levels, concerns, and plans for the future of their farming operations. The paper analyses characteristics of two increasingly important dairy production systems used in the Northeast. Averages from across the survey states (Maryland, Pennsylvania, New York, and Vermont) show that approximately 13% of dairy producers use management-intensive or rotational grazing and 7% use large, modern confinement systems with more than 300 cows. These more specialized production systems show many significant differences in farm and farmer characteristics, satisfaction levels, and plans for the future compared with farms using more traditional production systems. The changing structure of the dairy industry has potentially important implications for environmental quality, rural communities, and the food system.
  • Authors:
    • Lynd, L. R.
    • Gunderson, C. A.
    • Borsuk, M. E.
    • Davis, E. B.
    • Wullschleger, S. D.
  • Source: Agronomy Journal
  • Volume: 102
  • Issue: 4
  • Year: 2010
  • Summary: Fundamental to deriving a sustainable supply of cellulosic feedstock for an emerging biofuels industry is understanding how biomass yield varies as a function of crop management, climate, and soils. Here we focus on the perennial switchgrass (Panicum virgatum L.) and compile a database that contains 1190 observations of yield from 39 field trials conducted across the United States. Data include site location, stand age, plot size, cultivar, crop management, biomass yield, temperature, precipitation, and information on land quality. Statistical analysis revealed the major sources of variation in yield. Frequency distributions of yield for upland and lowland ecotypes were unimodal, with mean (+/-SD) biomass yields of 8.7 ± 4.2 and 12.9 ± 5.9 Mg ha-1 for the two ecotypes, respectively. We looked for, but did not find, bias toward higher yields associated with small plots or preferential establishment of stands on high quality lands. A parametric yield model was fit to the data and accounted for one-third of the total observed variation in biomass yields, with an equal contribution of growing season precipitation, annual temperature, N fertilization, and ecotype. The model was used to predict yield across the continental United States. Mapped output was consistent with the natural range of switchgrass and, as expected, yields were shown to be limited by precipitation west of the Great Plains. Future studies should extend the geographic distribution of field trials and thus improve our understanding of biomass production as a function of soil, climate, and crop management for promising biofuels such as switchgrass.
  • Authors:
    • Li, Y.
    • Kelly, K.
    • Eckard, R.
    • Chen, D.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 136
  • Issue: 3-4
  • Year: 2010
  • Authors:
    • Grace, P.
    • Kiese, R.
    • Butterbach-Bahl, K.
    • Rowlings, D.
    • Rochester, I.
  • Source: Soil Solutions for a Changing World: proceedings of the 19th World Congress of Soil Science
  • Year: 2010
  • Authors:
    • Anderson, R. L.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 25
  • Issue: 3
  • Year: 2010
  • Summary: Weeds are a major obstacle to successful crop production in organic farming. Producers may be able to reduce inputs for weed management by designing rotations to disrupt population dynamics of weeds. Population-based management in conventional farming has reduced herbicide use by 50% because weed density declines in cropland across time. In this paper, we suggest a 9-year rotation comprised of perennial forages and annual crops that will disrupt weed population growth and reduce weed density in organic systems. Lower weed density will also improve effectiveness of weed control tactics used for an individual crop. The rotation includes 3-year intervals of no-till, which will improve both weed population management and soil health. Even though this rotation has not been field tested, it provides an example of designing rotations to disrupt population dynamics of weeds. Also, producers may gain additional benefits of higher crop yield and increased nitrogen supply with this rotation design.
  • Authors:
    • Van Zwieten, L.
    • Kimber, S.
    • Rowling, D.
    • Grace, P. R.
    • Scheer, C.
  • Source: Soil Solutions for a Changing World
  • Year: 2010
  • Summary: An intensive field campaign was performed from April to June 2009 to assess the effect of biochar amendment on the emission of soil-borne GHGs from a sub-tropical pasture on acidic ferrosol. Over the whole measurement period high emissions of N2O and high fluxes of CO2 could be observed, whereas a net uptake of CH4 was measured. Only small differences in the fluxes of N2O and CH4 from the biochar amended plots (35.33 ± 4.83 μg N2O-N/m2/h, -6.76 ± 0.20 μg CH4 -C/m2/h) vs. the control plots (31.08 ± 3.50 μg N2O-N/m2/h, -7.30 ± 0.19 μg CH4 -C/m2/h) could be observed, while there was no significant difference in the fluxes of CO2. However, it could be observed that N2O emissions were significantly lower from the biochar amended plots during periods with low emission rates (< 50 μg N2O-N/m2/h). Only during an extremely high emission event following heavy rainfall N2O emissions from the biochar amended plots were higher than from the control plots. Our results demonstrate that pastures on ferrosols in Northern NSW are a significant source of GHG and that the amendment of biochar can alter those emissions. However, more field and laboratory incubation studies covering prolonged observation periods are needed to clarify the impact of biochar amendment on soil microbial processes and the emission of soil-borne GHGs.
  • Authors:
    • Walker, C.
    • Edis, R.
    • Li, H.
    • Chen, D.
    • Suter, H.
  • Source: Soil Solutions for a Changing World
  • Year: 2010
  • Authors:
    • Dalal, R. C.
    • Wang, W. J.
  • Source: Soil Solutions for a Changing World
  • Year: 2010
  • Summary: This study aimed to assess the feasibility of predicting ranges in N2O emission with a boundary line approach using a few key driving factors. Intact soil cores (9 cm dia. and ~20 cm in depth) were collected from pasture, cereal cropping and sugarcane lands and incubated at various temperature and moisture conditions after addition of different forms of mineral nitrogen (NH4+ and NO3⎯). The pasture and sugarcane soils showed greater N2O production capacity than the cropping soils with similar mineral N and organic C contents or under similar temperature and water filled pore space (WFPS%), and thus different model parameters need to be used. The N2O emission rates were classified into three ranges: low (< 16 g N2O/ha/day), medium (16 –160 g N2O/ha/day) and high (> 160 g N2O/ha/day). The results indicated that N2O emissions were in the low range when soil mineral N content was below 10 mg N/kg for the cropping soils and below 2 mg N/kg for the pasture and sugarcane soils. In soils with mineral N content exceeding the above thresholds, the emission rates were largely regulated by soil temperature and WFPS and the emission ranges could be estimated using linear boundary line models that incorporated both temperature and WFPS. Using these key driving factors (land use, temperature, WFPS and mineral N content), the boundary line models correctly estimated the emission ranges for 85% of the 247 data points for the cropping soils and 59% of the 271 data points for the pasture and sugarcane soils. In view of the fact that N2O emissions from soil are often very variable and difficult to predict and that the soil and environmental conditions applied in this study differed substantially, the above results suggested that, in terms of accuracy and feasibility, the boundary line approach provides a simple and practical alternative to the use of a single emission factor and more complex process-based models.