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This thesis is in four parts that report on the development of two procedures for the prediction of trafficability of tile-drained lowland soils in the Lower Fraser Valley of British Columbia. By these procedures one can predict trafficability either from soil water tension in the plough layer or from water table depth. A mathematical model developed in the Netherlands for the simulation of vertical non-steady flow of water in soils was tested by data collected in Spring from farmers' fields. The model predicted depth to the water table and, less accurately, tension in the top 15 cm in fields drained by tiles spaced at 30.5 m and 15.2 m. Cone penetration resistance (an index of soil strength) of soil in the field was found to be linearly dependent upon soil water tension between 0 and 100 - 175 cm of water. It was possible to predict the slope of this relationship for two mineral soils, but not for an organic soil. Trafficability tests with typical farm vehicles were carried out on one organic and two mineral soils at various degrees of wetness. Soil structure was significantly damaged after the first and third passes of the vehicles. The damage was greatest when the soil was near saturation. However, indices of structure could not be used per se as criteria for trafficable conditions. For each soil a relationship was established between soil strength and traction efficiency measured by wheelslip. A critical value of strength for trafficability was then obtained by using 20% wheelslip as a limiting value for traction efficiency. Reference to known strength-tension curves yielded critical tensions for trafficability. Soil strength was linearly dependent upon water table depth in Spring when evapotranspiration was small and when water table depth was less than 80 cm. Critical water table depths for trafficability inferred from this relationship were 53, 45, and 60 cm for Lumbum muck, Hallart silty clay loam (grassland), and Hallart silty clay loam (cultivated land), respectively. The effect of tile spacing on trafficability in Spring was assessed over a 2-year period. Evidence to support increased benefits due to the closer spacing was inconclusive in both soil types. When compared to undrained land the larger spacing of 30.5 m resulted in a significant increase in the number of trafficable days. Tile drainage was twice as important for the attainment of trafficable conditions in the muck as in the mineral soils. Two procedures for predicting trafficability of tile-drained farmland were described. Predictions by these procedures for two tile spacings in both soil types in Spring 1977 were within 3 days of one another and compared extremely well with dates on which measured water table depth and tension were considered adequate for trafficability. / Land and Food Systems, Faculty of / Graduate

The production of acid mine drainage (AMD) is catalyzed by iron-oxidizing bacteria primarily of the species Thiobacillus ferrooxidans. By inhibiting these bacteria, the production of AMD can be greatly reduced. One compound found to be effective in the inhibition of T. ferrooxidans is nitrapyrine. N-Serve, a product of Dow Chemical, Inc., is the commercially available form of nitrapyrine. This compound has been widely used in agriculture for nitrification inhibition. The purpose of this study was to determine the effectiveness of N-Serve in reducing the production of AMD under simulated field conditions. A column study was completed using a coal mine waste and a hard-rock mine waste. Eight columns containing 7kg of rock were established for each substrate. Three doses of NServe (22% nitrapyrine) were applied once at the beginning of this study: a high dose 2200 mg/kg, a medium dose 220 mg/kg, and a low dose 22 mg/kg. Duplicate columns were included for each N-Serve dose including two untreated columns to serve as a control for each substrate. Beginning the week after treatment, the columns were leached once a week for 29 weeks with deionized, distilled water (equivalent to 2.5 cm precipitation). Only the highest NServe dose produced a column leachate of significantly better quality than that of the controls. The acidity in the high-dose coal mine columns averaged less than 50 percent of the acidity in the control effluent from week 6 through the end of the study. A monolithic controlled release system utilizing acrylonitrile rubber was successfully developed and tested for use with nitrapyrine. This formulation should withstand the rigors of the environment and with minor modification could produce a variety of release rates. / Master of Science

The impact of natural and anthropogenic disturbances on catchment hydrological and biogeochemical dynamics are difficult or impossible to capture through experimentation or observation alone. Process-based simulation models can address this need by providing a framework for synthesizing data describing catchment responses to climate, harvest, fire, and other disturbances. However, existing models are either too simple to capture important process-level hydrological and biogeochemical controls on ecosystem responses to disturbance, or are too computationally expensive to simulate the local dynamics over large watershed areas, or require a high level of expertise to implement. To this end, a spatially distributed, physically based, eco-hydrological model (VELMA: Visualizing Ecosystems for Land Management Assessments) that is both computationally efficient and relatively easy to implement is developed. VELMA is a state-of-the-art model with real-time visualization tools that shows temporal and spatial patterns of state and flux variables, and is used to address the effects of changes in climate, land-use, and other interacting stressors on multiple ecosystem services such as timber production, carbon sequestration, regulation of water quality and quantity and reduction of greenhouse gases at scales relevant to formulating management decisions. In this study, VELMA was applied to the H.J. Andrews Experimental forest, an intensively studied watershed with observed daily temperature, precipitation, streamflow, and nutrient losses data. VELMA was first used to explore the factors that controls catchment response to forest harvest. Specifically, elucidate how forest harvest factors such as harvest location and amount control watershed hydrological and biogeochemical fluxes. Thereafter, VELMA was used to reconstruct and analyze the impact of two significant disturbance events − a stand replacing fire and a 100% clearcut − on vegetation and soil carbon and nitrogen dynamics. Finally, VELMA was used to explore the potential impact of climate change on catchment hydrological regime, site productivity and carbon and nitrogen dynamics at high spatial resolution relevant to formulating management decision. The main insights from this study include: (1) streamflow, nutrient losses to the stream, and gaseous carbon and nitrogen losses to the atmosphere are strongly sensitive to the location of harvest as a result of the spatial variation in soil water content, plant nitrogen uptake, soil organic carbon decomposition, nitrification, and denitrification within the watershed, (2) forested riparian buffers reduce water and nutrient losses to the stream through plant transpiration, plant nitrogen uptake, soil storage, and soil microbial decomposition, (3) following fire and harvest, losses of N from the terrestrial system to the stream are tightly constrained by the hydrological cycle and driven mainly by wet-season rain events large enough to generate hydrologic connectivity and flushing of nutrients along hillslopes, (4) climate change strongly impacts the hydrological regime in the Pacific Northwest as a result of less snowpack, earlier snowmelt, higher winter streamflow, lower summer streamflow, and soil moisture deficit, and (5) climate change increases plant and soil biomass accumulation as a result of longer growing season and higher soil organic decomposition, reduce water quality by increasing the amount of nutrients that reach the stream, and transforms the ecosystem into a net source of carbon to the atmosphere.

Indiana University-Purdue University Indianapolis (IUPUI) / The primary objective of this research involves mapping out and validating the existence of sub surface drainage tiles in a given cropland using Remote Sensing and GIS methodologies. The process is dependent on soil edge differentiation found in lighter versus darker IR reflectance values from tiled vs. untiled soils patches. Data is collected from various sources and a primary classifier is created using secondary field variables such as soil type, topography and land Use and land cover (LULC). The classifier mask reduces computational time and allows application of various filtering algorithms for detection of edges. The filtered image allows an efficient feature recognition platform allowing the tile drains to be better identified. User defined methods and natural vision based methodologies are also developed or adopted as novel techniques for edge detection. The generated results are validated with field data sets which were established using Ground Penetration Radar (GPR) studies. Overlay efficiency is calculated for each methodology along with omission and commission errors. This comparison yields adaptable and efficient edge detection techniques which can be used for similar areas allowing further development of the tile detection process.