The Biogeochemistry of nitrogen and phosphorus cycling in native shrub ecosystems in Senegal Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/0z709157j

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • Two native shrub species (Piliostigma reticulatum and Guiera senegalensis) are prominent vegetation components in farmers’ fields in Senegal. However, their role in nutrient cycling and ecosystem function has largely been overlooked. A study including both laboratory and field experiments was conducted to evaluate potential biophysical interactions of the two shrub species with soils and crops in Senegal. Carbon (C), nitrogen (N) and phosphorus (P) mineralization potential of soils incubated with residues of the two shrubs species was studied in laboratory conditions. Additionally, the effect of shrub-residue amendment on P sorption by soils was examined. Under field conditions, the effect of presence or absence of shrubs on crop productivity and nutrient recycling in soil was investigated. Another study examined shrub species effect on spatial distribution of nutrients and P fractions. Results showed shrub residues used as amendments immobilized N and P, which suggested these residues have limited value as immediate nutrient sources for crops. However, soils amended with shrub residues sorbed less P than unamended soils, indicating that when added to P-fixing soils, shrub residues could improve P availability to crops. In the absence of fertilization or when water was limiting, shrubs increased crop yield, likely through a combination of improved soil quality and water conditions associated with the shrub canopy and rhizosphere. The presence of shrubs increased nutrient-use efficiency over sole crop systems. Shrubs were shown to create “islands of fertility” that had greater C, N and P concentrations under their canopies than in open areas. Shrubs differed in their ability to modify soil properties. G. senegalensis had higher soil C and N under its canopy and lower pH than P. reticulatum. Sequential extraction of P fractions showed that NaOH-P, most of which is organic P, was the dominant P fraction in the soils. These results showed that, in the Sahel, shrubs are important components of cropping systems that should be conserved and actively managed.
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
Keyword
Subject
Rights Statement
Language
File Format
File Extent
  • 899516 bytes
Replaces
Additional Information
  • description.provenance : Made available in DSpace on 2007-01-18T17:08:57Z (GMT). No. of bitstreams: 1 Ekwe'sThesis.pdf: 899516 bytes, checksum: 190487435bbad723f1436b859043fe4d (MD5)
  • description.provenance : Submitted by Ekwe Dossa (dossae@onid.orst.edu) on 2007-01-10T03:10:57Z No. of bitstreams: 1 Ekwe'sThesis.pdf: 899516 bytes, checksum: 190487435bbad723f1436b859043fe4d (MD5)
  • description.provenance : Approved for entry into archive by Julie Kurtz(julie.kurtz@oregonstate.edu) on 2007-01-10T18:29:15Z (GMT) No. of bitstreams: 1 Ekwe'sThesis.pdf: 899516 bytes, checksum: 190487435bbad723f1436b859043fe4d (MD5)

Relationships

Parents:

This work has no parents.

Last modified

Downloadable Content

Download PDF

Items