• Authors:
    • Watanabe, T.
    • Tsuruta, H.
    • Akiyama, H.
  • Source: Chemosphere - Global Change Science
  • Volume: 2
  • Issue: 3
  • Year: 2000
  • Summary: Three nitrogen chemical fertilizers were applied to soil - controlled-release urea (CU), a mixture of ammonium sulfate and urea with nitrification inhibitor (AM), and a mixture of ammonium sulfate and urea with no nitrification inhibitor (UA). N2O and NO fluxes from an Andosol soil in Japan were measured six times a day for three months with an automated flux monitoring system in lysimeters. The total amount of nitrogen applied was 20 g N m-2. The total N2O emissions from CU, AM and UA were 1.90, 12.7, and 16.4 mg N m-2, respectively. The total NO emissions from CU, AM and UA were 231, 152, and 238 mg N m-2, respectively. The total NO emission was 12-15 times higher than the total N2O emission. High peaks in N2O and NO emissions from UA occurred for one month after the basal fertilizer application. The N2O emissions from CU and AM during the peak period were 50% of those from UA, and the NO emissions were less than 50% of those from UA. After the peak period, the N2O and NO emissions from CU were the highest for two months. A negative correlation was found between the flux ratio of NO-N to N2O-N and the water-filled pore space. A diel pattern with increased N2O and NO fluxes during the day and with decreased fluxes during the night was observed.
  • Authors:
    • Johnson, D. E.
    • Minami, K.
    • Heinemeyer, O.
    • Freney, J. R.
    • Duxbury, J. M.
    • Mosier, A. R.
  • Source: Climatic Change
  • Volume: 40
  • Issue: 1
  • Year: 1998
  • Summary: Agricultural crop and animal production systems are important sources and sinks for atmospheric methane (CH4). The major CH4 sources from this sector are ruminant animals, flooded rice fields, animal waste and biomass burning which total about one third of all global emissions. This paper discusses the factors that influence CH4 production and emission from these sources and the aerobic soil sink for atmospheric CH4 and assesses the magnitude of each source. Potential methods of mitigating CH4 emissions from the major sources could lead to improved crop and animal productivity. The global impact of using the mitigation options suggested could potentially decrease agricultural CH4 emissions by about 30%.
  • Authors:
    • McCarl, B. A.
    • Adams, D. M.
    • Alig, R. J.
  • Source: Journal of Agricultural and Applied Economics
  • Volume: 30
  • Issue: 2
  • Year: 1998
  • Summary: The forest and agriculture sectors are linked by having a portion of their land bases suitable for use in either sector. A substantial part of the southern land base is suitable for either forestry or agriculture use, with most of forestation on U.S. agriculture land in the South. We examine how land exchanges between forestry and agriculture are influenced by specific federal conservation and farm support policies, including changes in the Conservation Reserve Program. Reallocation of land is a significant part of the sectors' responses to the policies, along with intensification of timber management on existing southern forests.
  • Authors:
    • Kadoya, K.
    • Ishii, T.
  • Source: Journal of Japanese Society for Horticultural Science
  • Volume: 63
  • Issue: 3
  • Year: 1994
  • Summary: Effects of several kinds of charcoal applied to soil on citrus growth and vesicular-arbuscular mycorrhizal (VAM) development were investigated. Satsuma mandarin (Citrus unshiu Marc.) trees on trifoliate orange (Poncirus trifoliata Raf.) rootstocks were transplanted to root boxes using the soil mixed with charcoal derived from rice husk, citrus juice sediment or western spruce bark. The trees were inoculated with the spores of Glomus fasciculatum (Thaxter) Gerdemann and Trappe emend. Walker and Koske. Elongation of the roots in the charcoal treatments was more vigorous than that in the charcoal-free control. The fresh weigths of the root, shoot and the whole tree increased in response to charcoal application. The intensity of VAM infection in any charcoal treatment was higher than that in the control. In particular, the percentage of the infection in the rice husk charcoal plot was 41.5 and P concentration in the leaf exceeded that of the control. In a Citrus iyo orchard, the percentage of VAM infection was 52% in the rice husk charcoal plot, the highest among plots. The intensity in the Bahia grass (Paspalum notatum Flugge.) plot was next, followed by the third highest rate found in the abandoned plot which had not been cultivated in recent years. The lowest percentage of VAM infection was in a clean-culture plot. A microscopic observation also revealed that in a charcoal-treated plot there were many sites where VAM fungi infected the root.