Browsing by Subject "Soil Science"

Now showing 1 - 10 of 10
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    Comparison and Methods For Estimating Soil Surface Area
    (2016-01-14) Chi, Brian
    Soil Surface Area is important when analyzing land management and agriculture practices. Indirect methods of measuring Soil Surface Area are usually done through clay content. For this research I have compared both the Hydrometer method and Laser Particle Size Analyzer (LPSA) method as a means of analyzing soil texture. I then compared the Clay Content given from the Hydrometer and compared it to the Soil Surface Area data from the Brunauer–Emmett–Teller (BET) method. I found out that the LPSA didn't correlate to the Hydrometer method when analyzing soil texture. This means we can't use it as a reliable means of soil texture analysis. There needs to be further research on this subject before proving of it. The clay content given from the Hydrometer soil texture data correlated well with the BET SSA data. This means that the clay content does correspond to the soil surface area, this means that it can be used as a cheaper method to predict soil surface area. This discovery will be useful for future research within the soil science field.
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    Effects of Conversion to Management Intensive Grazing on Soil Quality
    (2011-01) Piotrowski, Keith Andrew
    Over the last two decades, increasing concern for environmental protection, as well as quality of life for themselves and their animals, has led some livestock owners to move away from confinement operations to management intensive grazing (MIG). MIG ensures sufficient monitoring and control over animal health, development, and the utilization of resources. Grazing pressure can be controlled through the number of animals allowed to graze an area, and timing can be adjusted to keep animals out of vulnerable areas such as wet or erodible ground during critical periods. In an attempt to compare benefits of management intensive grazing versus continuous grazing and row crop management, this project sought to determine the impacts of these three management systems on soil quality parameters. Physical, chemical, and biological indicators of soil quality were measured and compared statistically over an eight-year period. Results indicate that most biological indicators of soil quality are better in MIG and CG systems compared to RC. Physical indicators of soil quality indicated that RC management has poorer aggregation, but MIG can result in high bulk densities and penetration resistance. Comparison of chemical indicators of soil quality under the three management systems did not produce definitive results.
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    Fertility Levels of Minnesota Lawn and Garden Soils, 1972-76
    (Minnesota Agricultural Experiment Station, 1979) Grava, John; Fenster, William E.
    Chemical soil tests measure the relative nutrient status of the soil and assist in making recommendations for efficient and safe use of fertilizer and lime. Soil testing procedures have now progressed to the stage where the measurement of nutrient deficiencies as well as excesses is possible. The University of Minnesota Soil Testing Laboratory has given assistance to homeowners and turf managers since its establishment in 1950. Lime and fertilizer recommendations were originally prepared by soil scientists at the laboratory, and then from 1955 to 1972, by county extension agents. A computerized recommendation program for garden and lawn samples was introduced in 1972. The computer program was designed to give recommendations, based on the individual customer's situation, faster and more efficiently than previously possible. Soil test results have been summarized periodically since the establishment of the University of Minnesota Soil Testing Laboratory. The summaries published in 1964 reflected the native fertility of Minnesota soils (4). Occasionally, soil test results of samples received from Hennepin and Ramsey counties have been summarized to illustrate soil fertility problems encountered in the Twin City metropolitan area (Grava, J., 1958 and 1969, unpublished data). Soil test summaries are useful to the fertilizer and lime industries by pointing out areas of greatest need for their products. Extension personnel, teachers, and students find summary data helpful as teaching aids. The data reported here summarize 19,224 test results for garden and lawn soil samples received between April1, 1972, and December 31, 1976, by the University of Minnesota Soil Testing Laboratory. This report presents, in a general way, the fertility status of garden and lawn soils of Minnesota.
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    Fertility Status of Minnesota Soils As Shown By Soil Tests
    (Minnesota Agricultural Experiment Station, 1979) Grava, John; Fenster, William E.; Schoper, Robert P.
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    Field Research in Soil Science 1996
    (Minnesota Agricultural Experiment Station, 1996)
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    Field Research in Soil Science 1997
    (Minnesota Agricultural Experiment Station, 1997)
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    Modeling the impact of iIrrigation on precipitation over the Great Plains.
    (2011-08) Harding, Keith John Iliff
    Since World War II, the rapid expansion of irrigation throughout the Great Plains has threatened the sustainability of the Ogallala Aquifer. Irrigation has been shown to modify the surface energy and water budgets over the Great Plains by altering the partitioning of latent and sensible heating. An increase in latent heating from irrigation contributes to a cooler and more humid surface, which has competing impacts on convection. In this study, the Weather Research and Forecasting model was modified to simulate the effects of irrigation at sub-grid scales. Nine April-October simulations were completed for different hydrologic conditions over the Great Plains. Data from these simulations was assimilated into a back-trajectory analysis to identify where evapotranspired moisture from irrigated fields predominantly falls out as precipitation. May through September precipitation increased on average over the Great Plains by 4.97 mm (0.91%), with the largest increases during wet years (6.14 mm; 0.98%) and the smallest increases during drought years (2.85 mm; 0.63%). Large precipitation increases occurred over irrigated areas during normal and wet years, with decreases during drought years. On average, only 15.8% of evapotranspired moisture from irrigated fields fell out as precipitation over the Great Plains, resulting in 5.11 mm of May-September irrigation-induced precipitation. The heaviest irrigation-induced precipitation occurred over north-central Nebraska, coincident with simulated and observed precipitation increases. While irrigation resulted in localized and region-wide increases in precipitation, large evapotranspiration increases suggest that irrigation contributes to a net loss of water in the Great Plains.
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    Swat modeling of sediment, nutrients and pesticides in the Le-Sueur River watershed, south-central Minnesota.
    (2010-01) Folle, Solomon Muleta
    The Le Sueur River Watershed (LRW) of South-Central Minnesota drains 2,850 km² in the Minnesota River Basin. The watershed has an annual discharge of 230 mm and generates significant sediment and chemical pollution. The objective of this study was to quantify the spatial and temporal patterns of sediment, nutrient (nitrate-nitrogen, phosphorus) and pesticide (atrazine, acetochlor and metolachlor) losses from the LRW using the Soil and Water Assessment Tool (SWAT) model. The SWAT model was calibrated and validated from 2000-2006 in the Beauford sub-watershed. The calibrated model was applied to the entire LRW mainly to identify critical pollutant contributing areas and to evaluate effectiveness of alternative best management practices to reduce the loadings. The study has five major parts. The first part deals with hydrologic simulation. The second part identifies the relative contribution of upland and channel sediment sources. The third part deals with water quality impacts of land use and management alternatives on phosphorus and nitrogen losses to the LRW. The fourth part deals with pesticide losses. The fifth part deals with impacts of various biofuel production options on water quality. The LRW has estimated annual loadings of 1.0 kg TP/ha, 18 kg NO3-N/ha and 302,000 t/yr of sediment that contribute to water quality impairments in Lake Pepin and the Mississippi River. Alternative management practices are predicted to reduce upland sediment yield by up to 54%, nitrate-N losses by 22%, and phosphorus loadings by 64%. Overall, the SWAT model was able to accurately simulate the hydrology and transport of chemical pollutants under the land use systems, climate, hydrologic and physiographic settings of South-Central Minnesota.
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    Tracing the flow of carbon through ecosystems using stable isotope techniques
    (2010-03) Fassbinder, Joel J.
    The stable isotope 13C has become a popular tool for tracing carbon exchange between atmospheric and terrestrial reservoirs. Stable isotope techniques have been applied in a variety of ecosystems to partition the component fluxes of net CO2 exchange (FN) and have been incorporated into several atmospheric inversion models that estimate the ter- restrial carbon sink on the regional and global scales. While the use of stable isotope theory has helped provide valuable insight into the temporal and spatial variability of car- bon exchange, there has been some concern about the theory’s dependence on several key assumptions that have gone unverified due to limiting sampling techniques. Specific concerns regard the temporal variability of the isotopic composition of ecosystem respi- ration (δR) and its potential influence on ecosystem flux partitioning. In this thesis, an automated chamber system was combined with stable isotope techniques to evaluate and apply isotopic partitioning theory both in an agricultural ecosystem and in a climate con- trolled experiment using corn and soybean plants. Further, this new automated sampling technique was combined with isotopic flux-gradient measurements to examine the main factors controlling variability in ecosystem respiration and its isotopic composition. The findings from this thesis research may benefit land surface schemes that simulate isotopic fluxes for input to atmospheric inversion models.