Show simple item record

dc.contributor.advisorChairperson, Graduate Committee: Clain Jones.en
dc.contributor.authorMcCauley, Ann Michelleen
dc.description.abstractThere is renewed interest within agriculture to improve and sustain soil fertility. Legume crops can provide an alternative nitrogen (N) input to a cropping system through biological N fixation. The contribution of N from legume cropping systems depends on the quantity of N fixed and soil processes that influence soil N availability. The primary objectives of this project were 1) to evaluate the effect of planting and termination time on biomass production and N fixation by two legume green manure crops; and 2) to investigate the role of soil P availability on legume growth and N fixation. A two-yr dryland field study was conducted with three treatments: legume (field pea and lentil), planting time (spring and summer [2010 only]), and termination time (flower, intermediate [2009 only], and pod). Two methods, ¹⁵ N natural abundance and N difference, were used to quantify N fixation. In 2009, N fixed by spring-planted lentil was higher by pod than flower (P=0.03). There was no difference in N fixed by spring-planted pea among termination times, likely because of reduced precipitation during the middle of the growing season. In 2010, both spring-planted crops fixed more N by pod than flower (P<0.01) and more N was fixed by spring-planted crops than summer-planted crops (P<0.01). A greenhouse study was conducted in an unsterilized, low P soil (8 mg kg-soil -¹) with three treatments: legume crop (field pea or lentil), P fertilizer (0, 4, or 8 mg P kg -¹), and arbuscular mycorrhizae fungus (AMF) inoculum (AMF-, AMF+). Shoot biomass was sampled at flower, and N fixation was estimated with ¹⁵ N natural abundance method. Fertilization increased biomass yield and tissue N and P uptake for both crops (P<0.01) and increased N fixed by pea (P<0.01). Inoculation with AMF had little effect on measured parameters; however, there was an increase in pea biomass and N uptake in the AMF+ versus AMF- treatments at the 4P rate. Several variables that affect N fixation in semi-arid cropping systems were identified in this project, however further research assessing the effect of other soil and environmental conditions on N fixation and the cycling of fixed N in an agroecosystem is needed.en
dc.publisherMontana State University - Bozeman, College of Agricultureen
dc.subject.lcshCropping systemsen
dc.titleNitrogen fixation by annual legume green manures in a semi-arid cropping systemen
dc.rights.holderCopyright 2011 by Ann Michelle McCauleyen
thesis.catalog.ckey1739926en, Graduate Committee: Perry Miller; Catherine A. Zabinskien Resources & Environmental Sciences.en
mus.relation.departmentLand Resources & Environmental Sciences.en_US

Files in this item


This item appears in the following Collection(s)

Show simple item record

MSU uses DSpace software, copyright © 2002-2017  Duraspace. For library collections that are not accessible, we are committed to providing reasonable accommodations and timely access to users with disabilities. For assistance, please submit an accessibility request for library material.