The main goal of this research is to contribute to the understanding of nutrient transport and transformations in soil and its impact on groundwater on a large scale. This thesis specifically integrates the physical, chemical and biochemical nitrogen transport processes with a spatial and temporal Land Surface Scheme (LSS). Since the nitrogen biotransformation kinetics highly depends on soil moisture and soil temperature, a vertical soil nitrogen transport and transformations model was coupled with SABAE-HW. The model provides an improved interface for groundwater modeling to simulate soil moisture and soil temperature for a wide range of soil and vegetation. It is assumed that the main source of organic N is from animal manure. A-single-pool nitrogen transformation is designed to simulate nitrogen dynamics. Thus, the complete mathematical model (SABAE-HWS) is able to investigate the effects of nitrogen biochemical reactions in all seasons. This thesis reports the first field comparison of SABAE-HW using an extensive ten-year data set from BOREAS/BERMS project located in Saskatchewan, Canada. The performance of SABAE-HWS is calibrated and verified using 3 years (2002-2004) data from Carberry site in Canada, Manitoba. The effects of three rates of hog manure application, 2500, 5000, and 7500 gal/acre, was investigated to study the distribution of soil ammonium and soil nitrate within the 120 cm of soil profile. The results clearly showed that there is a good agreement between observed and simulated soil ammonium and nitrate for all treatment at the first two years of study. However, it was found a significant difference between observations and simulations at lower depths for 7500 gal/acre by the end of growing season of 2004. Also, 10 years climate data from OJP site was used to evaluate the effect of manure rates on the distribution of soil nitrate at Carberry site. The results indicated that to minimize the risk of nitrate leaching, the rate of manure application, accumulated soil nitrogen from earlier applications and the atmospheric conditions should be all taken into account at the same time. Comparing the results of SABAE-HWS and SHAW model also showed the importance of the crop growth model in simulating soil NH4-N and NO3-N.

No description available.

A range of adsorbents have been evaluated for the adsorption of selected herbicide compounds from aqueous solution. The adsorption performance of LF -1, a carbonised polymer produced in the laboratory, Amberlite XAD-4, a commercially available polymeric adsorbent produced by Rohm and Haas and MN-200, a HypersolMacronet polymer produced by Purolite, were compared with a commercial activated carbon, Chemviron F -400. The pore size distributions of the adsorbents have been investigated using nitrogen adsorption. F-400, LF-1 and MN-200 were found to contain similar microporous structures. The carbons also possess a significant degree of mesoporous structure, which may enhance the diffusion of organic species into the micropores. The pore size distribution for XAD-4 shows an almost exclusive meso/macroporosity with very little microporous structure. Spectroscopic analysis and titration of the adsorbents indicated a number of different oxygen functional groups. XPS and elemental analysis suggested higher oxygen concentrations than those obtained using direct titration, which was attributed to bound oxygen within the structure of the adsorbents. The adsorption capacity of phenol was assessed as a characterisation technique. The capacity of the carbons was much greater than the polymeric adsorbents. Analytical techniques were developed and validated for the determination of trace levels (0.1 parts per billion) of five herbicides; atrazine, benazolin, bentazone, imazapyr and tric1opyr. Single and multi-component adsorption isotherms are presented for trace concentrations of the herbicides in aqueous solution. The effect of pH and fulvic acid upon the adsorption was also investigated. Mini-column experiments were performed using multi-component mixtures. In all cases, the uptake of herbicides on F -400 is greater than on the other adsorbents. Regeneration of F-400 and MN-200 was investigated usmg solvent stripping techniques. Significant regeneration efficiencies were observed using ethanol at pH 12 and 50°C to make the technique a viable option.

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No description available.

Intercropping of a short-cycle legume crop and a longer-cycle non-legume crop has been suggested as a potentially beneficial intercrop combination. Most studies have concerned cereal and legume corps. Few have involved horticultural crops. In 1990 and 1991, a 56-day semi-leafless pea crop (Curly) and a 75-day lettuce crop (Paris Island Cos) were grown both as monocrops and as intercrops. Intercrops consisting of alternating rows of each crop, represented additive populations (56:100) of peas and lettuce. Three lettuce transplanting dates (June 19, 25 and July 4) and three nitrogen fertilizer rates (0, 50, 100 kg ha$ sp{-1}$) were tested. Peas were all sown on May 18. In addition, a new pea/lettuce intercropping pattern (45:82), consisting of alternating double rows of peas and lettuce, was tested in 1991. The $ sp{15}$N dilution method was also used to test for nitrogen transfer. Alternate row intercropped lettuce plant$ sp{-1}$ yields were, on average, 76% and 46% lower than their corresponding monocrop yields for the early and late transplanted lettuce, respectively. Declines in yield of 63% and 55% were reported for the double row intercropped lettuce for the early and late transplanting dates, respectively. Nitrogen fertilization significantly improved intercropped fresh lettuce yields but had no effect on monocropped lettuce. Pea yields m$ sp{-1}$ row were unaffected by intercropping. Alternate row land equivalent ratios (LER) ranged from 0.87 to 1.05 and from 1.06 to 1.63, in 1990 and 1991, respectively. The double row LER's ranged from 1.06 to 1.21 in 1991. The higher LER's in 1991 reflected higher pea yields. No evidence of nitrogen transfer to the lettuce crop was detected.

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No description available.

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1990. / Includes bibliographical references (leaves 164-173) / Microfiche. / xi, 173 leaves, bound ill. 29 cm

Typescript. / Thesis (Ph. D.)--University of Hawaii, 1967. / Bibliography: leaves 124-137. / xiv, 159 l graphs, tables