Carbon and nitrogen distribution and processes in forest and agricultural ecosystems
- 出版日期：2004.
- 页数：1 v. :
- 第一责任说明：Karl Jay Dria.
- 分类号：a875 ; a270
- ISBN：0496065866(ebk.) :
MARC全文
02h0029589 20120627113507.0 cr un||||||||| 120627s2004 xx ||||f|||d||||||||eng | 3148380 0496065866(ebk.) : CNY371.35 NGL NGL NGL a875 ; a270 Dria, Karl Jay. Carbon and nitrogen distribution and processes in forest and agricultural ecosystems [electronic resource] : a study involving solid- and liquid-state NMR and pyrolysis GC/MS / Karl Jay Dria. 2004. 1 v. : digital, PDF file. Adviser: Hatcher, Patrick G. Thesis (Ph.D.)--The Ohio State University, 2004. Forest and agricultural ecosystems comprise a large portion of the United States. Soil organic matter SOM) is viewed as the organic source of C and N for plants and microorganisms as well as an important C and N sink in these soils. To obtain a better understanding of C and N cycling in forest and agricultural ecosystems, one needs to understand humification, transformations, the chemistry of the various inputs and the chemical structural changes that these materials are subjected to on their path towards soil formation. For the forest study, a vertical transect of samples was collected from the forest canopy to the subsoil in the Harvard Forest before and after ten years of chronic N fertilization to determine compositional changes caused by ten years of fertilization and assess the effects of N loading. Currently, little is known about carbon structural types, quantity or quality preserved as a result of agricultural management practices. Soil samples and various OM inputs before and after degradation) were collected from agricultural soils under conventional and organic management practices. Samples from both ecosystems were characterized using elemental analysis, solid-state 13C and 15N NMR, and pyrolysis GC/MS. 13C NMR spectra from all samples contain signals associated with paraffinic, carbohydrate, aromatic and carboxyl structures. NMR spectra of soil inputs are dominated by carbohydrate carbons, while these intensities are severely diminished in the soil. An important observation is that the dominant persistent structures are paraffinic-type carbons in forest and agricultural ecosystems and, to a lesser extent, lignin structures in the agricultural system. However, comparison of the paraffinic signatures of the major OM inputs to the soils suggests that these are not the primary source of persistent paraffinic structures. In the forest system, N fertilization caused an increase in lipid-extractable paraffinic structures in oak leaves, an increase in N content in leaves, and slower litter decomposition in O and A soil horizons under pine and hardwood trees. In the agricultural system, minimal differences were observed between organic and conventionally managed soil, while crop residue lignin-to-nitrogen ratio differences were observed between management practices. Carbon ; Nitrogen Environmental aspects. ; Environmental aspects. Electronic dissertations. aeBook. aCN bNGL http://pqdt.bjzhongke.com.cn/Detail.aspx?pid=HZ8V6VA2H9g%3d NGL Bs1605 rCNY371.35 ; h1 bs1204