Master of Science in Veterinary Science / A investigation into soil nutrient and the change soil physical properties was carried out for three pasture systems for dairy cows; the complementary forage rotation (CFR) which comprised of brassica (Brassica napus )/clover (Trifolium resupinatum ) and maize (Zea mays) capable of achieving more than 40 t/ha, the typical intensive pasture (PI) with kikuyu grass (Penisetum clandestinum) over-sown with ryegrass ( Lolium multiflorum ) and the extensive system (PE); on two soil types (brown chromosol and black vertisol) . The study demonstrated that the CFR system was capable of doubling its yield by using similar fertilizers (N, P and K) and water inputs compared to these of the PI system resulting of greater nutrients (N and K) and water use efficiencies. Overall, the nutrient lost through runoff water was very limited for two intensive systems and nearly nil for PE system. Also similar trends were observed for soil physical properties in the intensive systems except for the topsoil (0-10 cm) where light acidification (P= 0.04) was recorded in the CFR probably due to the soil works before the maize sowing.

Master of Science in Veterinary Science / A investigation into soil nutrient and the change soil physical properties was carried out for three pasture systems for dairy cows; the complementary forage rotation (CFR) which comprised of brassica (Brassica napus )/clover (Trifolium resupinatum ) and maize (Zea mays) capable of achieving more than 40 t/ha, the typical intensive pasture (PI) with kikuyu grass (Penisetum clandestinum) over-sown with ryegrass ( Lolium multiflorum ) and the extensive system (PE); on two soil types (brown chromosol and black vertisol) . The study demonstrated that the CFR system was capable of doubling its yield by using similar fertilizers (N, P and K) and water inputs compared to these of the PI system resulting of greater nutrients (N and K) and water use efficiencies. Overall, the nutrient lost through runoff water was very limited for two intensive systems and nearly nil for PE system. Also similar trends were observed for soil physical properties in the intensive systems except for the topsoil (0-10 cm) where light acidification (P= 0.04) was recorded in the CFR probably due to the soil works before the maize sowing.

Master of Science in Veterinary Science / A investigation into soil nutrient and the change soil physical properties was carried out for three pasture systems for dairy cows; the complementary forage rotation (CFR) which comprised of brassica (Brassica napus )/clover (Trifolium resupinatum ) and maize (Zea mays) capable of achieving more than 40 t/ha, the typical intensive pasture (PI) with kikuyu grass (Penisetum clandestinum) over-sown with ryegrass ( Lolium multiflorum ) and the extensive system (PE); on two soil types (brown chromosol and black vertisol) . The study demonstrated that the CFR system was capable of doubling its yield by using similar fertilizers (N, P and K) and water inputs compared to these of the PI system resulting of greater nutrients (N and K) and water use efficiencies. Overall, the nutrient lost through runoff water was very limited for two intensive systems and nearly nil for PE system. Also similar trends were observed for soil physical properties in the intensive systems except for the topsoil (0-10 cm) where light acidification (P= 0.04) was recorded in the CFR probably due to the soil works before the maize sowing.

I explored the importance of decaying wood to survival and growth of trees in south coastal British Columbia, and the effect of decaying wood on the intensity of podzolization on mesic sites. A field pot study was carried out in both high light and low light conditions using woody and non-woody forest floor materials. After two growing seasons, Pseudotsuga menziesii, Tsuga heterophylla, and Abies amabilis seedlings growing in clearcuts had greater survival and growth in the non-woody substrate; however, in the understory, the effect was much less. The proliferation of western hemlock roots was used as an indicator of the value of decaying wood to trees. In both greenhouse trials (using seed sown on a series of planting pots with each half filled with either a woody substrate or a non-woody substrate), and in field sampling of woody and non-woody substrates in mature stands, the non-woody substrate had a larger density of fine and very fine roots compared to the woody substrates or mineral soil. Ten litres of concentrated solutions of non-woody humus substrate and woody substrates were leached through soil columns. Both the non-woody and woody solutions had similar mean pH but significantly different chemical properties. The non-woody solution leachate had greater net average output of dissolved organic C, Fe, and Mn. The mineral soil treated with the nonwoody solution had significantly greater concentrations of total N and pyrophosphate-extractable Fe. In the field, forest floor and soil samples were compared between pedons having large accumulation of decaying wood and pedons with non-woody humus forms. Despite large and significant differences in chemical properties between the two substrates, there were generally no significant differences between the chemical properties of the soils directly under these substrates. In most cases, the results of (3-analyses showed that the means were not pedologically different. Additionally, 18 pairs of zero tension plate lysimeters were installed under the two substrates. The lysimeter solutions showed no significant differences. I concluded that coarse woody debris appears not to have either a positive effect of increased productivity of trees or a negative effect of increased intensity of podzolization. / Forestry, Faculty of / Graduate

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The objective of this thesis was to validate the dynamic model SAFE (Soil Acidification in Forested Ecosystems) in a small deciduous watershed of southern Quebec. SAFE could then be used to: (1) identify which processes are governing acidification, and (2) assess the rates of acidification according to various forest conditions. / Soil and soil solution chemistry between unburned and burned zones following fire disturbance seventy-five years ago was examined within the watershed. Results showed two major, statistically significant, differences: (1) higher base status, and (2) lower soil solution N in the burned zone. High quality leaf litter of aspen and birch (burned zone) relative to that of sugar and red maple (unburned zone) has contributed to the enrichment of base cations in the forest floor. The enrichment of the forest floor did not however impoverish the B horizon as seen in other studies. Rather, fire enriched the soil in base cations and buffered the effect of forest regrowth in the B horizon. / The MAKEDEP model was used to reconstruct the time-series input files needed to run SAFE. In MAKEDEP, the availability of N determines tree growth which in turn, affects most of the processes involved in nutrient cycling. Regressions of measured deposition at the Hubbard Brook Experimental Forest and that of simulated deposition at the study site suggest MAKEDEP is suitable to model the deposition trends of all elements except Na. / SAFE was calibrated for the unburned and burned conditions at the study site. Fire disturbance and forest regrowth have produced different soil chemical composition within the zones as discussed above. SAFE was therefore validated at the study site as a function of its ability to reproduce soil chemistry under unburned and burned conditions. The simulated soil chemistry was in close agreement with the measured unburned soil conditions, but some processes would have to be clarified or accounted for with greater accurately, e.g., biological N fixation and N immobilization by myccorhizal fungi, to reproduce more accurately the measured burned soil chemistry. Simulated soil chemistry in the unburned zone reinforced nevertheless the conclusions of a few historical soil chemistry studies supporting the hypothesis that acid-sensitive forest sites of the United States underwent significant acidification during 1930--1980 during major input of acidity from the atmosphere. Model output suggests that cation nutrient deficiencies could occur in the long-term, but future Al phytotoxic responses are unlikely to occur due to a relatively high projected pH. (Abstract shortened by UMI.)

Archaeological artefacts excavated today are in a worse preserved state compare to those artefacts found before 1945. Previous research highlighted soil acidification as the main cause. However, not much research has been done to analyse other causalities, such as the spread of road salt during the wintertime and the potential deterioration that salt (sodium chloride) might cause on the physical cultural heritage. Nonetheless, it is proven that salt causes corrosion on infrastructure and on porous stone, masonry, and other composite materials in buildings. The aim of this work is to investigate how road salt move from the road surface (municipal– and state roads) and beyond, what factors might contribute to increased geographical spread and how we can limit the potential risk of damage associated with the spread of road salts to ancient historical sites. The research methods presented in this paper is a mix of field sampling study together with GIS– and literature analysis. The results show that the road salts spread according to an exponential decaying rate, where most of the road salts being spread 5–10 meters beyond the roadside. This means that cultural heritage sites within this buffer–area could be susceptible to salt induced damage to physical structures and deposited artefacts made from metals, rock, brick, and other material. Thereby it is pivotal to highlight the possible actions that can prevent the spread of road salts in a geographical landscape, and its effect on the physical cultural heritage.

This thesis compares the in situ water balance of common annual production systems (wheat, lupin, subclover and serradella) with a grazed perennial system (lucerne) at a site in the Avon Catchment, Western Australia. Using a physically-based water balance approach the value of a plant based solution in redressing the hydrological imbalance that has become a feature of much of the dryland agricultural region of Western Australia is investigated. The effectiveness of lucerne in providing greater available storage for buffering large rainfall events, as compared to the annual systems, is illustrated. Continued transpiration following out-of-season rainfall events maintains a larger available storage capacity. In contrast, the annual systems that are fallow over summer only withdrew a small fraction of water by soil evaporation between rainfall events. Under annual systems, the profile moisture store was sequentially increased to the extent that additional increments of rainfall could potentially contribute to deep drainage. A particular focus of this study has been to investigate the presence of soil constraints to root growth, and to assess how these constraints affect the water balance. A site survey indicated the soil penetration resistance was sufficient to impose a physical constraint to root growth. Published literature on the site shows soil acidity is also at a level imposing chemical constraints to root growth. A root growth model “Rootmodel”, for predicting root growth with and without soil constraints is examined in detail as a method for providing root growth parameters for inclusion into the numerical water balance model, SWIM based on Richard’s equation. Functions developed from “Rootmodel” adequately describe the effect of profile limitations to root growth, such as soil strength, moisture availability and temperature. Recommendations are made for inclusion of a growth suppressing function in “rootmodel” based on the chemical limitation of low pH. The effects of soil acidity on the root growth of several species is investigated experimentally and the resultant root data provided a reference point by which the simplified prediction of root growth built into SWIM could be adjusted using a linear reduction function. A similar linear reduction function is also employed to impose a physical constraint in the form of high penetration resistance.