Theses and Dissertations at Montana State University (MSU)
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Item Soil health response to cropping systems in semi-arid Montana(Montana State University - Bozeman, College of Agriculture, 2024) Ashford, Zane Ann; Chairperson, Graduate Committee: Catherine A. ZabinskiTraditional cropping systems in the northern Great Plains (NGP) were dominated by cereal-fallow rotations until the 1970s, resulting in increased soil erosion, decreased soil organic matter (SOM) accumulation, and declines in soil biological activity. Recent shifts toward continuous and more diverse no-till crop production attempt to increase sustainability, diversify economic opportunities, and keep up with the growing food demand without converting more land into agriculture. With a two-year study, I explored the effects of crop types in diverse, no-till, crop sequences on soil health in dryland and irrigated systems on one farm in semi-arid Montana, using biological indicators of potentially mineralizable nitrogen (PMN), soil enzyme activity (beta- glucosaminidase, beta-glucosidase, arylsulfatase, and acid and alkaline phosphatases), and permanganate oxidizable carbon (POxC), a measure of labile carbon. Crop sequences included four crop types -- cereals, oilseeds, legumes, and root crops. Root crops, namely sugar beet, drove soil responses in PMN, evident by increased plant-available N in soils following sugar beet. Soil enzyme activity, an indicator of nutrient cycling capacity, was strongly correlated with SOM, but did not follow a pattern based on crop type. Labile carbon changed in soils between years but did not respond consistently to crops. This research also explored the soil health gap by comparing soil health in cultivated systems to nearby grasslands. In a paired-site comparison on two farms in Montana, biological health indicators were 45% lower, on average, in cultivated soils compared to adjacent uncultivated soils. This difference was consistent with lower SOM averages, offering a simple assessment to quantify the maximum attainable soil health capacity within a specific agroecosystem. Soil acidification, a growing concern for producers across the NGP, contributed to 42% lower soil enzyme activity, based on four enzymes, compared to adjacent neutral pH cultivated soils. Enzyme activity was the only soil health parameter that was lower in acid soils compared to neutral pH soils, demonstrating the sensitivity of soil enzymes. Overall, these results indicate that biological soil health indicators are sensitive to changes in crop production, changing yearly, and provide farmers with the opportunity to fine- tune their management practices to meet their soil health goals.Item Assessing and improving sustainability of Camelina sativa through rhizobacterial inoculants and soil enzymatic activity(Montana State University - Bozeman, College of Agriculture, 2023) Stowell, Henry Douglas; Co-chairs, Graduate Committee: Catherine A. Zabinski and Jed O. EberlyCamelina sativa is an oilseed crop with potential to be used in biofuel production as an alternative to contemporary fossil fuels. To ensure biofuels are a more sustainable alternative , considerations and improvements must be made regarding the inputs and land-use needs of producing biofuel feedstocks. This research assessed the beneficial effects of inoculating C. sativa plant growth-promoting rhizobacteria candidates in greenhouse trials. Additionally, we explored agronomic responses of C. sativa and bulk soil enzymes in field trials across Montana to nitrogen and sulfur fertilizer treatments applied as pelleted urea and gypsum respectively. Co- inoculations of Pseudomonas putida ATCC 12633 and Bacillus thuringiensis ATCC 33679 were associated with seed yield increases of 60% relative to the uninoculated control. Co-inoculations of Pseudomonas brassicacearum 36D4 and B. thuringiensis ATCC 33679 were associated with significantly shortened root lengths of early seedlings but did not reduce total biomass. Field trials found a strong seed yield response to nitrogen treatments, with yields increasing with each treatment up to 168 kg N/ha. No significant yield response to sulfur treatments was observed. Additionally, fertilizer treatments did not have any significant effects on the activities of arylsulfatase, beta-glucosaminidase, beta-glucosidase, or urease in soils sampled at crop flowering. Rhizobacterial inoculants have potential to improve crop yields without additional inputs and should be tested on C. sativa in field settings. Urea applications can be used to improve C. sativa yields without any short term effects on soil enzymatic activity, but longer-term studies are needed to accurately determine the effects of the crop and its inputs on soil properties.Item In-nii (Bison bison L.) reintroduction to Amskapiipikini (Blackfeet) Nation homeland: relationships with ksahko (soils)(Montana State University - Bozeman, College of Agriculture, 2022) Tatsey, Latrice Dawn; Chairperson, Graduate Committee: Anthony HartshornIn-nii (American Bison) are returning to their Traditional Territories after being nearly wiped out of the Great Plains of North America and Canada. The in-nii are slowly returning to Native American tribes who have the resources to run reintroduction programs like that of the Amskapiipikini (Blackfeet). This in-nii reintroduction presented an opportunity to look at the effects of the return of in-nii to the Amskapiipikini, and what their influences might be on the soils, plants, and water resources of the Blackfeet Nation. This research project was conducted on the Blackfeet Buffalo (In-nii) Ranch and the adjacent RRJ Cattle Ranch, comparing the influence of in-nii and cattle on soil nutrient cycles and soil carbon dynamics. Soil samples were taken from locations on the landscape that were near water sources on lower elevations, mid hillslopes for mid-elevation sites and on hilltops at higher elevations. Soil characteristics included soil organic matter (SOM), nitrate, pH, cation exchange capacity (CEC), and exchangeable calcium, potassium, sodium, and magnesium. Only two (CEC, magnesium) appeared to have been influenced by in-nii and cattle. The remaining soil characteristics were little influenced by grazer type. Substrate-induced respiration was also measured in the lab to see how microbes decomposed SOM (carbohydrates and other molecules) to release energy and CO2; we found no evidence of differences between in-nii- and cattle-influenced soils. Finally, we measured field respiration rates and water infiltration rates at multiple fence line sites; field soil respiration rates increased when soil had water infiltrated after the dry readings, soils also increased the time to absorb water after the first infiltration tests were run. Our preliminary results suggest that the reintroduction of in-nii to these lands has not yet resulted in measurable differences in soil-related properties of the Blackfeet Nation. Even so, the return of the in-nii for the Amskapiipikini is also about understanding the importance of using cultural science when studying the ecology of a system. Doing this can create an understanding of the traditional ways of knowing while bringing cultural healing and restoring connections between Amskapiipikini, in-nii, and land.Item Effect of bio-cementation on thermal properties of silty sand(Montana State University - Bozeman, College of Engineering, 2022) Gunyol, Pinar; Chairperson, Graduate Committee: Mohammad KhosraviIn recent years, there has been an increasing interest in the use of biological technologies in geotechnical engineering to improve thermal properties of geomaterials. Urea hydrolysis is a chemical reaction which can generate favorable conditions that result in the precipitation of calcium carbonate. Certain microbes or plant sources produce the urease enzyme which catalyzes the hydrolysis of urea to form carbonate (CaCO 3) to bond soil particles. Cementation located between the grain particles acts as a highly conductive heat transfer path by increasing the contact area between the sand particles. In this thesis, the applicability of bio-cementation via microbially induced calcite precipitation (MICP) on silty sand specimens with different fines contents of 0%, 5%, and 15% were investigated. MICP promoting fluids were injected into sand-filled columns and the resulting calcium conversion was measured. At the end of the injections, the MICP treated specimens were tested for cementation uniformity. The amount of precipitated CaCO 3 gradually decreased as the distance from the injection ports increases. The observed bio-cementation distribution could be attributed to the filtration of bacterial cells through the soil particles. The resulting effect of filtration on CaCO 3 distribution was observed to be more prominent for silty sands, presumably due to the presence of fine grains. Thermal conductivity measurements were assessed after each pulse during the MICP treatment using a TR-3 sensor. Under the saturated and untreated conditions, thermal conductivity increased with increasing fines content. In addition, MICP treatment can increase the thermal conductivity of saturated silty sands with the increasing number of treatment pulses. An increase of about 18% in thermal conductivity of the soil was achieved at an average CaCO 3 content of 10.7% presumably due to the formation of calcium carbonate bridges binding the soil grains together. The results presented herein suggests that MICP treatment can be a viable option to increase the thermal conductivity of soils in the range of fines content studied here (less than 15%). The findings of this research could be used to improve the efficiency of geothermal boreholes and other energy geo-structures using MICP by improving thermal conductivity of dry and partially saturated soil.Item A northern Great Plains soil response to a one-time compost application(Montana State University - Bozeman, College of Agriculture, 2022) Haviland, Molly C.; Co-chairs, Graduate Committee: Jed O. Eberly and Anthony HartshornMany organic cropping systems depend on organic amendments for maintaining crop yields and soil fertility. Weed control is often achieved through tillage, which can degrade soil and lead to a loss of soil organic matter (SOM). The objective of this two-year study was to determine how wheat (Triticum aestivum L.) grain yield, protein concentration, above ground biomass (AGB), and indices of soil health including SOM, substrate-induced respiration (SIR), and field soil respiration (FSR) measurements would respond to compost applications in a Northern Great Plains dryland cropping system on Farnuf loam soils (fine-loamy, mixed, superactive, frigid Typic Argiustolls) near Geraldine, Montana. Cattle manure compost was applied once in spring of 2019 at 0 (Control), 14 (Low), 46 (Medium), and 137 (High) Mg dry weight ha-1 to a spring wheat and cover crop rotation. Compost did not significantly impact wheat yield, AGB, or SOM content (p > .05). Differences were detected for the Low and High compost treatments compared to the Control in overall SIR rates and concentrations but not during any of four measurement periods (0, 7, 24 and 96 hours). The highest (median + or = interquartile range [IQR]) SIR concentrations occurred at 24 hours (Control [25 + or = 2], Low [28 + or = 15], Medium [23 + or = 5], and High [28 + or = 5] mg CO2-C g-1 SOC). Cumulative FSR, however, was significantly higher (2.5 Mg C ha-1) for soils receiving the Medium compost rate compared to all other treatments including the Control, which respired ~2 Mg C ha-1 over the four-month measurement period. Together, these results indicate that when cattle manure compost is applied to fine-textured dryland soils, wheat grain yields and protein concentration, as well as soil properties like SOM, do not appear to be enhanced in the short-term. These results also indicate that, one year after application, compost treatments may be detectable via soil health indices such as SIR and FSR, but these results can be inconsistent. As demand for organically grown, dryland crops increase, future research should clarify the most sensitive, robust, and cost-effective indices of soil health capable of guiding improved agricultural practices, including compost amendments.Item Integrating livestock into small-scale vegetable farming systems(Montana State University - Bozeman, College of Agriculture, 2021) Benson-Feagler, Trestin Thea; Chairperson, Graduate Committee: Megan Van Emon; D.L. Regan, M.L. Van Emon and C.J. Yeoman were co-authors of the article, 'Effects of integrating livestock into small-scale vegetable farming systems' submitted to the journal 'Sustainable agriculture research' which is contained within this thesis.Since World War II, modern agriculture systems have shifted to low-diversity monoculture crops, specializing in a singular species and generally separating those crops from livestock. Such systems require high inputs including fertilizers, herbicides and tillage, all of which may reduce ecological potential of farmland. Small-scale farms are becoming more popular due to recent interest in local eating and sustainability. To improve their environmental sustainability, some small-scale farms have incorporated livestock back into cropping systems. Soil health measurements can be valuable in understanding the impacts livestock have on small- scale farming systems as soil is the growth medium for vegetation. The objectives of this study were to evaluate nutrient cycling, microbial communities and compaction in response to grazed versus un-grazed vegetable cropping systems and use this information to understand the interaction between soil biology, nutrient cycling and livestock when integrated in a variety of vegetable production systems. Soil and biomass samples were collected over three years (2017- 2020) before and after sheep grazing occurred on three farm locations in the Northern Great Plains. Soil samples were analyzed for soil microbial diversity, bulk density and soil nutrients. While I found no consistent differences in soil nutrients, bulk density or soil microbial diversity, my results indicate that integrating livestock into small-scale vegetable farming systems did not negatively impact soil quality. Results from this study may help demonstrate to farmers and livestock operators the importance of an integrated approach, for those that already practice this approach there is affirmation that integration is feasible and purposeful and also become the starting point for further research into a little studied topic.Item Response of soil bacterial communities to cropping systems, temporal changes, and environmental conditions in the northern Great Plains(Montana State University - Bozeman, College of Agriculture, 2021) Ouverson, Laura Tindall; Chairperson, Graduate Committee: Fabian D. MenalledSoil bacterial communities are essential components of the soil ecosystem that support crop production. However, agriculture in semiarid drylands and their associated soil bacterial communities face increasingly warmer and drier conditions due to climate change. Two complementary studies were conducted to assess the response of soil bacterial communities to cropping systems, temporal changes, and soil temperature and moisture conditions in semiarid, dryland agricultural systems of the Northern Great Plains. The first study focused on soil bacterial community response to crop phase in contrasting cropping systems (chemical inputs and no-till, USDA-certified organic tilled, and USDA-certified organic sheep grazed) over a growing season. Organic grazed management supported more diverse bacterial communities than chemical no-till, though diversity in all systems decreased over the growing season. Organic grazed bacterial communities were distinct from those in the organic tilled and chemical no-till systems. An interaction between cropping system and crop phase affected community dissimilarity, indicating that overarching management systems and environmental conditions are influential on soil bacterial communities. The second study evaluated soil bacterial communities in a winter wheat - cover crop or fallow rotation. Observations were conducted in the summer fallow and two cover crop mixtures differing by species composition and phenologies, terminated by three different methods (chemical, grazing, or haying), and subjected to either induced warmer/drier or ambient soil conditions. Only the presence and composition of cover crops affected bacterial community dissimilarity, where mid-season soil bacterial communities were distinct from early season and fallow communities. Bacterial communities responded to an interaction between the presence and composition of cover crops and environmental conditions, but not termination. No treatment effects were observed in bacterial communities in 2019, which could be attributed to above average rainfall. The results of these studies suggest cover crop mixtures including species tolerant to warmer and drier conditions can foster diverse soil bacterial communities compared to fallow soils. Overall, these studies contribute to a better understanding of how soil bacterial communities respond to soil health building practices in the Northern Great Plains. Cropping systems can foster unique soil bacterial communities, but these effects may be moderated by environmental and temporal conditions.Item Soil legacy effects alter plant volatile emissions in response to diversified cropping systems(Montana State University - Bozeman, College of Agriculture, 2020) Malone, Shealyn Chelsea; Chairperson, Graduate Committee: David K. Weaver and Amy Trowbridge (co-chair); David K. Weaver, Fabian Menalled, Tim Seipel, Justin B. Runyon, Lila Hamburg, Megan L. Hofland and Amy M. Trowbridge were co-authors of the article, 'Cropping systems alter crop volatile cues important for insect pests through soil legacy effects' which is contained within this thesis.; David K. Weaver, Tim F. Seipel, Fabian D. Menalled, Megan L. Hofland, Justin B. Runyon and Amy M. Trowbridge were co-authors of the article, 'Soil microbes alter herbivore-induced volatile emissions in response to cereal cropping systems' submitted to the journal 'Plant and soil' which is contained within this thesis.Soil microbes can influence the emissions of plant volatile organic compounds (VOCs) that serve as host-location cues for insects and their natural enemies. The influence of the soil microbial community on the plasticity of plant VOC synthesis and emissions is particularly important in agricultural settings where crop rotations and management practices cause significant shifts in the soil microbiome. Studies have shown agricultural soils to influence plant-insect interactions through changes in foliar chemistry, but their potential to alter VOC emissions is unknown. To determine the effect of diversified agricultural practices on crop VOC emissions through microbe-mediated soil legacy effects, I measured VOCs from wheat (Triticum aestivum L.) in a series of field and greenhouse experiments. In Chapter II, I determined the effect of the soil microbiome on VOCs in the greenhouse by first measuring VOCs from wheat plants grown in sterilized soil or soil with added inoculum from an agricultural field. Next, to determine the effect of diversified agricultural practices on VOC phenotypes, I measured VOCs from wheat plants in the field in rotation with either fallow or a mixture of cover crops that was terminated by grazing cows. Finally, in Chapter III, I explored the interactive effect of herbivory and the soil microbiome on VOC emissions in a full factorial experiment in which wheat grown in soil inoculum from wheat-fallow or wheat-cover crop rotation that was subjected to larval feeding by the wheat stem sawfly (WSS; Cephus cinctus Norton), a major pest of wheat. Across all studies I found that soils associated with a higher microbial diversity--cover crop soils and inoculated soils--tended to emit more total VOCs and blends that would likely increase pest resistance to the WSS through 1) shifts in key bioactive compounds and 2) enhanced herbivore-induced VOC emissions. Results also suggest that soil microbes may be more likely to alter plant VOCs when plants experience abiotic or biotic stressors. Together, these results suggest that agricultural practices may indirectly influence plant resistance through microbe-altered VOCs, and these effects are more likely to occur when plants experience additional stressors, such as herbivory or drought.Item Effects of grazing after wildfire on soil health in eastern Montana(Montana State University - Bozeman, College of Agriculture, 2021) Hanson, Joshua Todd; Chairperson, Graduate Committee: Clayton B. Marlow; Clayton B. Marlow, Kurt O. Reinhart, Lance T. Vermeire and Sam A. Wyffels were co-authors of the article, 'Effects of grazing after wildfire on indicators of soil health in eastern Montana' submitted to the journal 'Fire ecology' which is contained within this thesis.Rangelands are resilient to grazing and fire. However, the resilience of rangelands may be degraded by livestock grazing too soon after wildfire. Due to the growing interest in soil health and its link to sustainable grazing, following a large wildfire (109,346 ha, Lodgepole complex in 2017) we tested the effect of grazing (grazed verses no grazing) on three indicators of soil health in ponderosa pine savvanas of the northern Great Plains. We measured indicators of soil hydrologic function (i.e., soil hydraulic conductivity), properties related to nutrient cycling (i.e., soil organic matter, plant available nutrients, pH), and soil structure (i.e., aggregate stability) in 2019 and 2020. Grazing occurred two out of three years following the fire. Most indicators of soil health were not appreciably affected by grazing post-fire. However, we detected a marginally significant negative effect of grazing on soil organic matter. Specifically, soil organic matter was 7% greater in ungrazed than grazed areas. No other grazing treatment effects were detected. Several soil health metrics varied between sampling years. Our results suggest that grazing(two out of the three years) following fire is unlikely to negatively affect many indicators of soil health of ponderosa pine savannas in the northern Great Plains. The increased organic matter observed by resting did not have an appreciable impact on the other soil health metrics. These findings suggest that soil health indicators are relatively resilient to grazing after wildfire and have implications for grazing policy post-fire.Item Screening field pea (Pisum sativum L.) for tolerance to high salinity conditions(Montana State University - Bozeman, College of Agriculture, 2020) Tracy, Jacob D.; Chairperson, Graduate Committee: Kevin McPheeField pea (Pisum sativum L.) is an important salt-sensitive crop utilized in rotation with cereals in semi-arid cropping systems in the Northern Great Plains (NGP). Saline soils (EC > 4 dS m -1) negatively impact over 10.8 million acres in Montana, the second largest producer of field pea in the US. Despite its global importance, few studies have explored field pea response to high salinity conditions outside of germination testing and even fewer have looked at tolerance to sodium sulfate (Na 2SO 4), the dominant salt affecting plant growth in the NGP. In this study, 311 accessions comprising the genetically diverse USDA Pisum single plant (PSP) core collection were screened under high Na 2SO 4 conditions in germination and seedling experiments. Germination screening was conducted in petri dishes within a dark growth chamber. Accessions received H 2O (control) or 16 dS m -1 Na 2SO 4 (highly saline) solution for 8 days. The mean percent germination compared to the control was used as the indicator for tolerance. A preliminary greenhouse concentration series experiment using 7 levels of Na 2SO 4 (0, 3, 6, 9, 12, 15, and 18 dS m -1), supported screening seedlings at 9 dS m -1 Na 2SO 4. Greenhouse screening was conducted in plastic pots of coarse sand media. Accessions received a nutrient solution (control) or 9 dS m -1 Na 2SO 4 and nutrient solution daily. Salinity symptom scores were assessed on days 21, 28, 35, and 38 post-sowing using a visual growth response scale of 1-9 (healthy-dead). Phenotypic measurements and the Area Under the Injury Curve (AUIC) were used as indicators for tolerance. A Genome Wide Association Study (GWAS) was conducted using the phenotypic data collected and a large dataset of 68,222 Single Nucleotide Polymorphisms developed from the USDA PSP plus core collection. Potential candidate breeding germplasm conferring high salinity tolerance at the germination and seedling growth stages was identified. Significant marker-trait associations were discovered for all traits measured, providing potential Marker-Assisted Selection (MAS) opportunities.