Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
Browse
4 results
Search Results
Item Effects of saline-sodic water on EC, SAR, and water retention(Montana State University - Bozeman, College of Agriculture, 2003) Robinson, Kimberly MarieItem Effects of irrigation water quality and water table position on plant biomass production, crude protein, and base cation removal(Montana State University - Bozeman, College of Agriculture, 2003) Phelps, Shannon DaleItem Soil water flow and irrigated soil water balance in response to Powder River Basin coalbed methane product water(Montana State University - Bozeman, College of Agriculture, 2005) Buchanan, Margaret MacNeill; Chairperson, Graduate Committee: Jon M. Wraith.A repacked soil columns experiment and a series of computer soil water balance simulations were conducted to examine potential impacts of coalbed methane (CBM) water from Montanaαs Powder River Basin (PRB) on soil water flow and water balance in PRB soils. CBM water is often high in sodium, which may separate soil clay particles, particularly after soil exposure to low-salinity rainfall or snowmelt, and when soils contain expansible smectite clay minerals. Aggregates in soils exposed to sodic water may swell and slake, and clays and other fine particles may disperse, clogging soil pores and slowing or preventing soil water flow. In the soil columns experiment, A and B horizon materials from sandy loam, silt loam, and clay loam soils were pre-treated with water having salinity and sodicity typical of PRB CBM water or of Powder River (PR) water currently used for irrigation in the basin. Tension infiltrometer measurements were used to determine infiltration flux, first using pre-treatment water, and subsequently deionized (DI) water, simulating rainwater. Measurements were compared by pre-treatment water, horizon, and soil type. Under pre-treatment water testing, the sandy loam and clay loam soils pre-treated with CBM water exhibited smaller infiltration flux values than when pre-treated with PR water. Only the sandy loam soil showed a greater decrease in infiltration flux with DI water on soils pre-treated with CBM relative to PR water pre-treated soils. There was no difference in infiltration flux decrease with DI water between A and B horizon soils, or between smectite and non-smectite soils. The soil water balance numerical simulations modeled potential effects of sodic irrigation waters on sandy loam, silt loam, clay loam and silty clay PRB soils under sprinkler or flood irrigation, during one growing season. Baseline soil water retention functions were constructed for the five soils, and adjusted via trends identified in the literature to create five additional functions for each soil, simulating exposure to five increasingly sodic irrigation waters. Simulation results showed greater impact of sodic irrigation under flood than sprinkler irrigation. The fine sandy loam and silty clay loam soils exhibited the fewest changes in water balance partitioning, while the silt loam and silty clay soils showed the greatest changes, especially in increased runoff and reduced transpiration.Item Response of grass species to soil salt content and coversoil depth on lands developed for coalbed methane(Montana State University - Bozeman, College of Agriculture, 2005) Mitchem, Melissa Deanne; Chairperson, Graduate Committee: Douglas J. Dollhopf.In areas where land is disturbed to extract energy resources such as coalbed methane, improper soil management may result in soils impaired by elevated salinity. The objectives of this study were to evaluate the emergence and growth of three native grass species (Pseudorogeneria spicata, Hesperostipa comata, and Pascopyrum smithii) as a function of i) soil salt content and matric potential, and ii) coversoil depth overlying a saline substrate. The first study consisted of nine treatments, combining three soil salinity levels (0.80, 5.0 and 11.0 dS/m) and three matric potential ranges (-0.1 to -1.0, -1.0 to -7.0, and less than -7.0 bars). Seedling emergence, plant height, aboveground biomass, and belowground biomass were significantly decreased by increasing soil salinity and decreasing soil moisture. A correlation analysis showed matric potential to be more significantly correlated to seedling emergence and growth than soil salinity. This resulted in large reductions in growth when soil moisture was decreased within a salinity treatment. Emergence for plants grown in elevated salinity increased as much as 26.7 % when moisture was high. At low soil moisture, elevated salinity resulted in emergence losses as high as 88.3 %. Losses in aboveground biomass ranged from 23.0 to 97.9 % at moderate salinity and 27.3 to 98.5% at high salinity. Results indicate that the impacts of elevated soil salinity are highly influenced by soil moisture. Irrigation will be an important factor in revegetation of saline soils. Also, investigators studying plant growth on saline soils must closely consider the impact of soil moisture on study results. For the second study, a substrate consisting of a mixture of soil and geologic stratum was salinized to an EC of 11.0 dS/m. Non-saline coversoil was applied on top of the saline substrate at depths of 0, 5, 10, 15, 30 and 45 centimeters. Aboveground and belowground biomasses were significantly greater with increased coversoil depth, with depths of 15, 30 and 45 cm producing similar results. Results suggest that coversoil is necessary to improve plant growth on a saline substrate, but applications of less than 45 cm may be adequate.