Agroecosystem management effects on nitrous oxide and methane emissions.

摘要

Global budgets of many greenhouse gases and stratospheric ozone depletors are still poorly understood. Two such gases are CH₄ and N ₂O; both are greenhouse gases and the latter an ozone depletor. A need exists for further understanding of effects agroecosystem management has on these two gases. Four studies were conducted to better document the effects of several management practices.; The first study was located near Shorter, Alabama, to determine the interactive effects of tillage method (conventional tillage and no tillage) and wheel traffic (traffic and no traffic) on denitrification from a Coastal Plain soil. For ambient field conditions, a trend for a tillage by season interaction was shown (P ≤ 0.14), while for optimum field conditions, a tillage by season interaction was observed (P ≤ 0.06). For ambient field conditions, greater denitrification was observed in the spring and from conventionally tilled soil.; A second field study was conducted at Auburn University to determine the influence of commercial N fertilizer and legumes on the emission of N₂O-N and CH₄-C from a no-till cotton (Gossypium hirsutum L.)-corn (Zea mays L.)-rye (Lolium perenne L.) rotation. It was found that average flux of N₂O-N for each treatment across all sampling dates was 65.0, 55.2, and 50.8 mg N ₂O-N ha−1 h−1 for no N with winter legume, complete fertilization, and no N without winter legume treatments, respectively, with winter legume consisting of clover (Trifolium pratense L).; A third field study near Auburn University was conducted in a bermudagrass [Cynodon dactylon (L.) Pers.] pasture to determine the influence of the red imported fire ant [Solenopsis invicta (L.) Buren] on soil emission of three greenhouse gases. It was concluded that for a bermudagrass pasture in Alabama, the influence of red imported fire ants can increase annual emissions of N₂O-N and CO₂-C by 0.2% and 1.1%, respectively, and CH₄-C emission from ant influenced soil can reduce annual CH ₄-C oxidation by only 0.2%.; A fourth study conducted at Auburn University was designed to determine the source-sink relationship of three greenhouse gases in three Alabama soils (Black Belt, Coastal Plain, and Appalachian Plateau regions) amended with swine waste. (Abstract shortened by UMI.)