Date of Award:

1992

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Natural Resources

Department name when degree awarded

Range Science

Advisor/Chair:

Neil E. West

Abstract

The objectives of this study were to determine the effects of two forms of polyacrylamide (PAM) conditioners (Cross-linked and Non-cross-linked PAM) on evaporation, saturated hydraulic conductivity, water retention, crust and crack formation of soils, seed germination, and seedling and tubeling growth.

The two PAM conditioners, 0.2% concentration by weight, were mixed with seven soils of different textures (sandy loam, silt, silty clay loam, silt loam, fine sand, medium sand, and coarse sand) to investigate the effects on evaporation, saturated hydraulic conductivity, and water retention. Soil samples of different textures were brought to field capacity and placed in a growth chamber for two weeks to measure evaporation under a controlled environment.

A second experiment was carried out in the field to determine the effects of the two PAM conditioners on seedling emergence of crested wheatgrass, Agropyron desertorum, as well as on soil cracking, penetrometer resistance, and soil moisture. The two PAMs were mixed with a silt loam Xerollic Calciorthid at 0.2% concentration by weight. Seedling emergence was monitored directly for two weeks. Soil moisture was measured by TDR. Cracking was described by photographic means. Penetrometer resistance was measured by a hand-held. penetrometer.

The third experiment was also carried out in the field, using the same soil texture as in experiment 2, to investigate the effects of the two PAMs on soil moisture at depths between 25 to 45 cm and on sagebrush (Artemisia tridentata) growth.

Evaporation was found to be significantly lower in the fine-textured controls than under the two PAM treatments. The sandy loam and sandy soils experienced significantly higher evaporation from the controls. The two PAM conditioners significantly reduced saturated hydraulic conductivity on all soil textures. Water retention increased in the PAM-treated textures at the matric potential range used (0.0, 0.05, 0.1, 1.5 MPa) • The PAM application also did not improve grass seedling emergence or improve soil moisture, and did not have any significant affects on sagebrush growth. Larger cracks were found in the two plots treated with PAM than the controls. Lower penetrometer resistance occurred in the two PAM treatments compared to the untreated control.

From this study, it can be concluded that the application of PAM conditioners, at relatively high concentrations used, could be more viable on sandy textures. Other researchers are advised to try lower application rates than used here, particularly with finer textured soils.

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