Browsing by Author "Wamono, Anthony Walekhwa"

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    Effects of Calcium Based Surface Amendments on Hydraulic Conductivity and Selected Physical Properties of Subsurface Drained Sodic Soils
    (North Dakota State University, 2016) Wamono, Anthony Walekhwa
    Managing excess soil water in agricultural fields in the Northern Great Plains through subsurface drainage increases the risk of sodification in high-risk soils. Leaching sodic soils with low electrical conductivity (EC) water, rainfall, may result in the swelling of soil, dispersion of clay particles and consequently the breakdown of soil structure leading to changes in physical and mechanical properties of soils (e.g., reduced infiltration, hard-setting and reduced trafficability). In this dissertation, the effectiveness of calcium amendments of gypsum and spent lime, a byproduct of the processing sugar beets, with water-management treatments of free drainage (FD) and no drainage (ND) on improving physical properties of the soil were examined. The first objective was to evaluate the effects of drainage and surface treatments on the penetration resistance (PR). The second objective was to use infiltration tests with a mini-disk tension infiltrometer and a Cornell sprinkle infiltrometer to investigate changes in hydraulic properties. Lastly, a drawbar dynamometer was used to measure draft on a chisel plow as it was pulled across the plots by a tractor equipped with an auto-guidance system and instrumentation interfaced with the controller area network of the tractor. The results show that the PR values of plots with gypsum application at high rate of 22.4 Mg ha-1 (GH) were significantly higher than other surface amendments. GH increased the hydraulic conductivity of the soil matrix compared to spent lime application at rate of 22.4 Mg ha-1 (SL); however, the overall flow of water through the soil profile, including the soil matrix and the macropores, was not affected. Both GH and gypsum application at high rate of 11.2 Mg ha-1 (GL) lowered the drawbar power requirements compared to spent lime application. For many farmers, drainage enables early planting and the adding of ameliorants will safeguard against further sodification of their fields.
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    Micro-Pore Parametrics for Optimal Hyperfiltration of Conservative Contaminants
    (North Dakota State University, 2012) Wamono, Anthony Walekhwa
    In compacted Na-montmorillonite membranes, the pore-size, and surface charge will influence filtration processes of solutes. A dead-end hyperfiltration setup was utilized to: (a) study the intrinsic retention, membrane filtration coefficient, and solution flux of different membrane configurations and (b) model nitrate break-through effluent concentrations through the membrane. Scanning electron microscopy and solute analytical techniques were employed to assess what critical components of micro-pore parametrics would prevail in a non-bio stimulated remediation of simulated agricultural wastewater. Although high content bentonite membrane configurations (5 g clay at 2500 psi) offered better solute rejections with a 30 percent increase in the cell concentration, the compaction of the membrane had the most deterministic influence on the solution flux. The results reveal hyperfiltration of nitrate ions is a function of the compaction pressure and composition of bentonite in the mixed soils. High content bentonite membranes compacted at the optimal pressures offer promising solutions to nitrate contaminant remediation.