Theses and Dissertations at Montana State University (MSU)
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Item Effect of summer fallowing, perennial crop cover and conservation reserve practices on soil nitrate distribution(Montana State University - Bozeman, College of Agriculture, 1994) Pannebakker, Lynn S.; Chairperson, Graduate Committee: Jim BauderDryland agriculture is an economically feasible method of producing crops in some parts of the semi-arid regions of the mid-west and western United States. Summer fallowing, which is commonly practiced in these regions, serves to replenish soil moisture and plant-available nitrate-nitrogen (N0 3--N), while also stabilizing production and more uniformly distributing the work load. In areas where dryland agriculture is concentrated, summer fallowing may lead to N0 3--N contamination of ground-water due to lack of plant uptake of excess water and N. Under certain conditions of precipitation, soil percolation, slope, and cropping intensity, summer fallowing has been shown to cause elevated N03--N concentrations in shallow groundwater wells. These elevated N0 3--N levels have been detected in several areas of the U.S. Two areas where high N0 3--N concentrations have been repeatedly found in groundwater samples are in northeastern and central Montana. Judith Basin and Fergus Counties of Montana were selected for soil sampling to assess any differences in soil NO3--N concentrations under three different land use systems: 1) crop fallow rotation, 2) acreage enrolled in the USDA Agricultural Stabilization and Conservation Service (ASCS) conservation reserve program (CRP), 3) and rangeland. Soil samples were collected to a depth of three m (10 ft) at four different sites in each county. Soil samples from all sampling depths at each of the eight sites were analyzed for gravel percent (>2 mm diameter) , N0 3--N load, and N0 3--N concentration. Samples from 0 m to 0.6 m were also analyzed for total-N concentration. Trends in soil N0 3-N give evidence that summer fallowing may be the cause of N0 3--N in shallow groundwater in some areas Of Montana where dryland cropping is practiced. Overall, average soil N0 3--N concentration throughout the sampled soil profile was 4.2, 2.0, and 1.3 mgkg-1 for the crop fallow, CRP, and rangeland land use practices, respectively. Average N0 3--N concentration in Fergus County ranged from 2.5 mgkg-1 to 20.4 mgkg-1 under crop fallow while it ranged from only 0.9 to 6.2 mgkg-1 and from 0.9 to 4.2 mgkg-1 for the CRP and rangeland uses, respectively. Average N0 3--N concentration in Judith Basin County ranged from 1.4 mgkg-1 to 6.9 mgkg-1, 0.6 mgkg-1 to 2.0 mgkg-1, and from 0.8 mgkg-1 to 1.4 mgkg-1 under crop fallow, CRP, and rangeland land use systems, respectively. Assuming that extensive use of crop fallow causes increased N0 3--N concentrations under some conditions, alternative land use management practices may be effective in reducing N0 3--N levels in such areas.Item Wheat stem sawfly parasitism in varying field sizes and tillage systems in dryland wheat in Montana(Montana State University - Bozeman, College of Agriculture, 2001) Runyon, Justin BlakeItem Nitrogen fertilizer strategies and empirical models for rainfed spring wheat(Montana State University - Bozeman, College of Agriculture, 1994) Mahmood, ShaukatItem Evaluating selected soil morphological, classification, climatic, and site variables that influence dryland small grain yield on Montana soils(Montana State University - Bozeman, College of Agriculture, 1984) Burke, Thomas HaroldItem A preliminary evaluation of herbicides in dryland cropping systems for saline seep control(Montana State University - Bozeman, College of Agriculture, 1974) Tasker, Alan VonnItem Forage-crop substitutions on dryland units sensitive to shift(Montana State University - Bozeman, College of Agriculture, 1956) Norman, Terry N.Item The problem of the unsuccessful dry farm in the northern Great Plains(Montana State University - Bozeman, College of Agriculture, 1938) Halcrow, Harold G.Item Resource productivity on Montana dry-land crop farms(Montana State University - Bozeman, College of Agriculture, 1952) Fienup, Darrell F.Item The use and effectiveness of financial and physical reserves in Montana's dryland wheat area(Montana State University - Bozeman, College of Agriculture, 1959) Hjort, Howard W.Item The Montana Agricultural Experiment Station and the development of dry farming techniques : 1902-1920(Montana State University - Bozeman, College of Letters & Science, 1975) McGorry, Peter Dennis