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Item Pulse crop management to enhance biological nitrogen fixation in the northern Great Plains(Montana State University - Bozeman, College of Agriculture, 2022) Baber, Kaleb Wade; Chairperson, Graduate Committee: Clain Jones; Clain Jones, Perry Miller, Sydney Atencio, Samuel Koeshall and Peggy Lamb were co-authors of the article, 'Lentil nitrogen fixation response to fertilizer and inoculant in the northern Great Plains' submitted to the journal 'Agronomy journal' which is contained within this thesis.; Clain Jones, Kevin McPhee, Perry Miller and Peggy Lamb were co-authors of the article, 'Assessment of nitrogen fixation among pea and lentil varieties in the semiarid northern Great Plains' submitted to the journal 'Agronomy journal' which is contained within this thesis.Pulse crop production has increased dramatically in Montana and the surrounding northern Great Plains over the past few decades. Through N fixation, pulse crops, including pea and lentil, can reduce N fertilizer requirements, both by replacing non N-fixing crops and positively contributing to soil N pools for subsequent crop uptake. Three studies were conducted in Montana over three years to investigate pulse crop management practices that enhance N fixation of pea and lentil. The first study investigated lentil N fixation response to fertilizers and inoculant types. Inoculant and S fertilizer each increased N fixed by lentil in 40% of site-years, but response was not well correlated with cropping history or soil sulfate-S levels. In one site-year, N fixation appeared to continue increasing at the highest tissue S concentration while seed yield plateaued below that highest level, indicating that S fertilizer could increase the soil N benefit of lentil even if a yield response is not expected. Potassium fertilizer nor inoculant type influenced N fixed. The second study assessed differences in N fixation among lentil and pea varieties. Amounts of N fixed varied in 75% and 50% of site-years for lentil and pea, respectively. Differences among varieties were sometimes large, up to 45 kg N ha-1. Two lentil varieties, CDC Richlea and Riveland, were frequently among the top N-fixers, while no pea varieties consistently fixed more N than others. Correlations between N fixed and seed yield ranged from weak to moderate, and pea more frequently had positive relationships than lentil. The third study evaluated N fixation response of two pea varieties to inoculant formulations. Inoculant formulation did not impact N fixed by either variety, and the uninoculated treatment performed as well as the inoculated treatments. This suggests producers may not need to inoculate pulse crops to achieve sufficient N fixation when effective rhizobia populations exist in their fields. These results contribute to the researchers' understanding of N fixation by pulse crops in the region. Together, these studies can help producers in the northern Great Plains better manage pea and lentil, improving both economic and environmental sustainability of the region's cropping systems.Item Integrating crop diversity, forage crops, and targeted grazing to manage Avena fatua L.(Montana State University - Bozeman, College of Agriculture, 2021) Wong, Mei-Ling; Chairperson, Graduate Committee: Fabian D. Menalled and Tim F. Seipel (co-chair)Wild oat (Avena fatua L.) is one of the most difficult weeds to manage in spring cereal crops and causes large economic losses throughout the Northern Great Plains. The continual use of herbicides for wild oat management has selected for herbicide resistant and multiple herbicide resistant biotypes and has left no selective herbicide options for farmers in small-grain fields. To sustain crop production, this thesis aimed to develop ecologically based practices to manage wild oat populations. We evaluated the impact of spring wheat height, seeding rate, crop type, forage termination method, and tillage on wild oat tiller density, biomass, and seed production. Two studies were conducted: (1) from 2017 through 2019 in Bozeman, Montana and (2) from 2018 through 2019 in Moccasin, Montana. The first study examined the combined effect of spring wheat height and seeding rate on its competitiveness against wild oat. We found that the tall near-isogenic wheat line did not have greater wild oat suppression than the short line. Spring wheat seeded at a higher than recommended rate reduced wild oat biomass and seed production only when nitrogen fertilizer was applied. The second study assessed management practices including integrating lentil, fall and spring forage mixture, sheep grazing and tilled fallow, in addition to spring wheat height and seeding rate. Forage mixtures, sheep grazing, and tillage were the most successful tactics in suppressing wild oat growth and seed production. However, wild oat suppression was not different between spring wheat and lentil, regardless of spring wheat height and seeding rate. Our results indicate that spring wheat height was not correlated with increased suppression of wild oat. A higher seeding rate of spring wheat also did not increase wild oat suppression; we suggest that fertilization may be needed to enhance crop competitiveness. Integrating forage crops with sheep grazing has the best potential to reduce the wild oat seed bank. This information can help redesign cropping systems. However, there is a continual need to develop other integrated weed management techniques to limit wild oat growth and seed production and to reduce reliance on herbicides.Item Impacts of crop rotations and nitrogen fertilizer on soil biological factors in semi-arid Montana(Montana State University - Bozeman, College of Agriculture, 2021) Fouts, Willa Constance; Chairperson, Graduate Committee: Catherine A. ZabinskiEvaluating the effects of cropping and fertilizing techniques is key to informing agricultural best practices. We must continue monitoring how we manipulate soils in order to preserve and cultivate high-quality soil ecosystems that can support us in the face of climate change and widespread soil loss and deterioration. We assessed the effects of common agricultural practices in Montana by measuring biological indicators of soil quality in the 18th year of a field plot experiment with 100% and 50% the recommended rate of synthetic nitrogen (N) fertilizer and crop rotations incorporating wheat, fallow, and legumes. The biological indicators measured were four soil extracellular enzymes, potentially mineralizable N (PMN), and microbial biomass. We sampled once in spring 2020 and subsampled in the fall. We also tested whether enzymes and PMN were correlated to aboveground plant residue, which was represented by the sum of the dried plant mass from past two years left on the plots after harvest. Plant residue was positively correlated with the C, N, and S-cycling enzymes and to PMN. The positive correlation between PMN and residue reflects that increased biomass inputs could increase easily mineralizable N. Soil with the high N-rate had a slightly higher geometric mean enzyme activity. This could be from the resulting increase in plant residue. The high N-rate treatment slightly decreased soil PMN but was not affected by crop rotation treatments. Fallow systems had lower enzyme function overall, indicating a lessened fertility and decomposition rate compared to continuously cropped treatments, which keep the soil covered with a crop for more months out of the year. The positive correlations of plant residue, along with the general lower performance of the fallow systems, especially the tilled fallow rotation, support that aboveground biomass inputs are a driver in soil ecosystem function. Continuous no-till crop rotations have increased aboveground plant organic matter, which could increase nutrient cycling and decomposition, and thereby soil biological quality and fertility.Item Effects of a barley chromosome 6H grain protein QTL on agronomic traits, malt quality traits, and stomatal control under two irrigation and nitrogen fertilization regimes(Montana State University - Bozeman, College of Agriculture, 2018) Mangel, Dylan J. L.; Chairperson, Graduate Committee: Andreas FischerCereal grain protein concentration (GPC) is an important quality parameter, with high GPC desirable when grain is used for food or feed, while low (typically below 12- 13%) GPC is needed when barley grain is used for malting. A major QTL controlling grain protein has previously been identified on barley chromosome 6H. Based on the comparison with a co-linear region on wheat chromosome 6B, the functional status of a gene coding for a NAC transcription factor (HvNAM-1) is responsible for controlling whole-plant senescence, nutrient remobilization from leaves to developing grains, and grain protein concentration. In this context, the purpose of this study was the analysis of the influence of a low- vs. a high-grain protein allele at this locus on barley agronomic and malting quality parameters in different genetic backgrounds. Integration of the low-protein allele stably lowered GPC by 1.6-1.8%, in both years and across all combinations of genetic backgrounds and management practices. Lines with the low-protein allele matured 1.4 to 2.5 days later, dependent on management, and had stably lower malt protein and diastatic power. Effects on additional agronomic and malt quality parameters including yield, test weight, percentage of plump kernels, free amino nitrogen and alpha-amylase activity were subtler and depended on the genetic background tested. Our data also provide important information on the influence of soil N and water availability on malt quality characteristics. Overall, use of the chromosome 6H low-grain protein allele stably lowered grain and malt protein levels without important negative influences on any of the tested agronomic and malt quality parameters, indicating its usefulness in the development of new malting barley germplasm. The studied chromosome 6H GPC QTL also controls expression of a gene coding for a glycine-rich RNA-binding protein (HvGR-RBP1) that may improve drought tolerance. Stomatal conductance and canopy thermal imaging assays did not show consistent effects of the allelic state of the GPC QTL on stomatal control. However, our data showed important correlations between stomatal conductance, canopy temperature depression and agronomic parameters including yield, demonstrating the value of the performed assays for variety selection and breeding.Item Price relationships in the U.S. nitrogen fertilizer industry(Montana State University - Bozeman, College of Agriculture, 2018) Gumbley, Thomas J.; Chairperson, Graduate Committee: Anton BekkermanThis study estimates the price dynamics in the U.S. nitrogen fertilizer industry, measures information flow efficiency in spatially separated fertilizer markets, and measures to what extent structural changes in corn and natural gas markets may have altered these price dynamics and information flow relationships. A vector error correction model is used to measure the short-run and long-run relationships between nitrogen fertilizer markets, natural gas markets, and corn markets. The results show that price information flows from the central market of New Orleans to inland regional markets. The efficiency of this information flow increased in the period after the Renewable Fuel Standards increased the demand for corn.Item Effects of rangeland fertilization on forage crop yield and quality(Montana State University - Bozeman, 1978) Nemeth, Chris EdwardItem Fallow replacement and alternative fertilizer practices : effects on nitrate leaching, grain yield and protein, and net revenue in a semiarid region(Montana State University - Bozeman, College of Agriculture, 2015) John, Andrew Augustus; Chairperson, Graduate Committee: Clain JonesHigh nitrate concentrations in groundwater have been observed in agricultural regions worldwide. In the Judith River Watershed of central Montana, groundwater nitrate concentrations have increased from 10 to 23 mg L-1 over the span of 20 years. Nitrate leaching from agricultural fields is a major concern for growers and stakeholders in the region. Little research has been conducted in dryland semiarid regions on the effects of agricultural practices on nitrate leaching. We conducted a 2-yr study comparing three alternative management practices (pea rotation, controlled-release urea, split nitrogen application) to grower standard practices (fallow, conventional urea, spring broadcast urea) on grain yield, grain protein, net revenue, and the amount of nitrate leached. Eight field treatment interfaces were established across three farms and each treatment was in duplicate per year. Ten soil and biomass sampling locations were designated on both sides of the interface. Net revenue was calculated by enterprise budgets constructed from local and state data. Nitrate leaching was calculated using a nitrogen mass balance equation. Replacing pea with fallow decreased winter wheat grain yield and protein yet had no effect on net revenue during the first year of the study (2013). In the second year, pea-winter wheat earned $83 ha -1 more (P<0.1) than fallow-winter wheat. Neither fertilizer alternative management practice had an effect on net revenue. In the 2013 treatment year, wheat after pea leached less nitrate (20 kg N ha -1) than wheat after fallow (56 kg N ha -1), indicating more deep percolation of nitrate with fallow practice. In the 2014 treatment year, a greater amount of nitrate leached (P<0.1) while using controlled-release urea than conventional urea, possibly in part because the controlled release urea was applied earlier than conventional urea. The results of our study revealed that replacing fallow with pea can decrease the amount of nitrate that leaches out of the root zone. Also, this practice either increased or had no effect on net revenue, revealing its ability to be economically feasible for a grower to implement. Based on our findings, future research should likely focus on practices that decrease rates of deep percolation.Item Modification of grain drill openers to place fertilizer below the seed(Montana State University - Bozeman, College of Agriculture, 1985) Palmer, John ThomasItem Evaluation of nitrogen fertilization and grazing effects on a porcupine grass (Stipa spartea var. curtiseta) community(Montana State University - Bozeman, College of Agriculture, 1974) Roath, Leonard RoyItem Effects of nitrogen, phosphorus and sulfur on the yield, growth and quality of canola (Brassica napus L.)(Montana State University - Bozeman, College of Agriculture, 1994) Popove, Gregory B.