Impacts of agricultural management and landscape factors on soil carbon and nitrogen

Loading...
Thumbnail Image

Persistent link to this item

Statistics
View Statistics

Journal Title

Journal ISSN

Volume Title

Title

Impacts of agricultural management and landscape factors on soil carbon and nitrogen

Published Date

2011-12

Publisher

Type

Thesis or Dissertation

Abstract

Agricultural management has altered soil carbon (C) and nitrogen (N) inputs, losses, and turnover rates. Understanding how management interacts with landscape factors to regulate soil C and N losses is essential to addressing climate change. Through research conducted in agricultural systems in Minnesota I investigated: (1) how the loss of corn root-derived C as carbon dioxide (CO2), and N as nitrous oxide (N2O) differed among five management systems, and (2) how hillslope position and soil moisture affected the size and turnover of soil C pools. In a field study using stable isotope techniques, I found that the fraction of root-derived C and N emitted as CO2 and N2O, the C and N emission factors, were 35% and less than 1% respectively. Individually, each emission factor was lower in systems with increased rotation diversity. Conversely, the relationship between C and N emission factors differed with tillage and fertilization intensity, not with rotation diversity. The magnitude of root-derived C and N emission factors has agricultural policy implications. Currently an emission factor of 1% is used for all N inputs to agricultural systems. My research suggests that a lower emission factor would better reflect N2O emissions from belowground N sources.In a laboratory study, both position and soil moisture significantly impacted the size and mean residence time of soil C pools along a low slope hillslope. Intact core sections of the upper four horizons from three hillslope positions were incubated at 50, 75, 90 and 100% water-filled pore space (WFPS) for 355 days. Total soil C (TC), N, and the resistant fraction of TC (64%) increased downslope. Under saturated conditions, 100% WFPS treatment, the size and mean residence time of the labile C fraction (<1% of TC) increased. Increased moisture, between 50% and 90% WFPS, also lengthened the mean residence time of slow C. In this low slope landscape I found effects of both position and moisture on C pool dynamics; soil moisture had the most significant impacts on labile C pool size and the slow C pool mean residence time.

Description

University of Minnesota Ph.D. dissertation. December 2011. Major: Ecology, Evolution and Behavior. Advisor: Jennifer Y. King. 1 computer file (PDF); ix, 156 pages.

Related to

Replaces

License

Collections

Series/Report Number

Funding information

Isbn identifier

Doi identifier

Previously Published Citation

Other identifiers

Suggested citation

Van Vleck, Harriet E.. (2011). Impacts of agricultural management and landscape factors on soil carbon and nitrogen. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/162273.

Content distributed via the University Digital Conservancy may be subject to additional license and use restrictions applied by the depositor. By using these files, users agree to the Terms of Use. Materials in the UDC may contain content that is disturbing and/or harmful. For more information, please see our statement on harmful content in digital repositories.