Impact of a red clover winter cover crop on carbon and nitrogen mineralization by microorganisms in soil aggregates Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/tx31qk97c

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • Although legumes have been widely studied for their nitrogen-fixing ability, it is uncertain to what extent legume cover crops achieve their nitrogen-fixing potential under the climatic conditions encountered in western Oregon. Furthermore, it is unknown what factors control the proportions of legume cover crop N that are either sequestered into soil organic matter, or that contribute to the N requirements of the following summer crop. Soil was sampled in mid-September 1997, after harvest of a summer broccoli crop, from plots located at the North Willamette Research and Extension Center, Aurora, Oregon. Soil was sampled from main plots that had been either winter cover cropped with red clover (LN₀ and LN₁) or fallowed during the winter period (FN₀ and FN₁), and specifically from sub-plots in which the following summer crop had received either zero (N₀) or an intermediate (N₁) rate of N fertilizer as urea. Levels of total organic carbon (TOC), total Kjeldahl nitrogen (TKN), and readily mineralizable C and N were measured in both whole soil samples and in different aggregate-size classes (<0.25, 0.25-0.5 0.5-1.0, 1.0-2.0, and 2-5mm) prepared by dry sieving the soil. Aggregate size-class distribution was not affected by the cover crop treatment. Although there was no significant effect of cover crop treatment on either TKN or TOC levels in whole soil samples, TOC levels were consistently higher in the small aggregate size-classes <1 mm of the fallow than the legume treatment. There was a significantly higher level of mineralizable C in the <0.25 mm size class of the legume than the fallow treatment. There was a trend for the level of mineralizable N to be greater in soil from the legume than the fallow treatment. However, N fertilizer had a significant positive effect on the level of readily mineralizable N in both fallow and legume cover-cropped treatments, it had a negative effect on TKN levels among all aggregate-size classes. There were differences in the levels of mineralizable N measured among the aggregate-size classes, and immobilization of N between 20 and 40 days of incubation also differed among the aggregate-size classes.
Resource Type
Date Available
Date Copyright
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Academic Affiliation
Non-Academic Affiliation
Subject
Rights Statement
Peer Reviewed
Language
Digitization Specifications
  • File scanned at 300 ppi (Monochrome) using Capture Perfect 3.0 on a Canon DR-9050C in PDF format. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR.
Replaces
Additional Information
  • description.provenance : Submitted by Kirsten Clark (kcscannerosu@gmail.com) on 2012-09-21T19:36:30Z No. of bitstreams: 1 NdiayeAissatou1999.pdf: 1673107 bytes, checksum: 629055e3e8025cc6ff1e067f899c0271 (MD5)
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2012-09-21T21:50:48Z (GMT) No. of bitstreams: 1 NdiayeAissatou1999.pdf: 1673107 bytes, checksum: 629055e3e8025cc6ff1e067f899c0271 (MD5)
  • description.provenance : Made available in DSpace on 2012-09-21T21:50:48Z (GMT). No. of bitstreams: 1 NdiayeAissatou1999.pdf: 1673107 bytes, checksum: 629055e3e8025cc6ff1e067f899c0271 (MD5) Previous issue date: 1998-11-24
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2012-09-21T21:48:03Z (GMT) No. of bitstreams: 1 NdiayeAissatou1999.pdf: 1673107 bytes, checksum: 629055e3e8025cc6ff1e067f899c0271 (MD5)

Relationships

In Administrative Set:
Last modified: 08/03/2017

Downloadable Content

Download PDF
Citations:

EndNote | Zotero | Mendeley

Items