Effects of bulk density and soil strength on the growth of blue wildrye (Elymus glaucus Buckl.)

Graduation Date

2006

Document Type

Thesis

Program

Other

Program

Thesis (M.S.)--Humboldt State University, Natural Resources, Rangeland Resources and Wildland Soils, 2006

Committee Chair Name

Susan Edinger-Marshall

Committee Chair Affiliation

HSU Faculty or Staff

Keywords

Soil compaction, Dry bulk density, Elymus glaucus Buckl., Humboldt State University -- Theses -- Natural Resources, Soil strength

Abstract

The effects of soil compaction on plant productivity have frequently been studied in the context of agriculture, but less information exists about this relationship in the context of rangeland resources. Domestic livestock grazing has been cited as contributing to soil compaction and loss of native species on rangelands. This study used a greenhouse experiment to identify the effects of soil compaction on the productivity of seedlings of Elymus glaucus Buckl. (blue wildrye), a native perennial grass. Compaction was characterized by bulk density and by soil strength as a function of bulk density and water content. Plants were grown in three levels of bulk density (1.00, 1.25, and 1.55 g cm-3) at three water potentials (-33, -500, and -1500 kPa). Shoot production increased significantly at high water potential and moderate bulk density (ANOVA, p0.05). Root production decreased significantly at high bulk density and low water potential (ANOVA, p0.05). Soil strengths exceeding 3 MPa and 6 MPa were present in treatments producing the greatest shoot and root biomass, respectively. Similar, intermediate levels of production occurred across the range of bulk densities in this study and across a wide range of soil strength, suggesting that no threshold bulk density or soil strength exists that limits E. glaucus production. Biomass production was greatest when water was readily available. Negative effects of highly compacted soils were often less severe when water was available. This suggests the importance of water in biomass production as well as in the ability of plants to tolerate compacted soil. In field settings, where water availability may be highly variable, soil compaction as it affects water availability to plants may be more important in influencing E. glaucus establishment than physical impedance itself.

https://scholarworks.calstate.edu/concern/theses/z890rw599

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