No description available.

The aim of this work was to assay the effects of previous history of organic amendment to soils in the field on the ability of those soils to mineralise mustard, a non-legume green manure. Soil and 15N labelled mustard mineralisation was followed in laboratory microcosms. Volatilised N was assayed by direct acid trapping of N in glass fibre disks, followed by direct combustion isotope ratio mass spectrometry. Animal manures, green manures and straw added to the soil in the field in the previous season, same season and for 7 years continuously did not significantly affect these soils' ability to mineralise mustard in microcosms. Nitrification and mineralisation were the dominant processes during the first 12 days of incubation. Volatilisation rates were 1000-fold lower than mineralisation or nitrification rates. Mustard N accounted for between 1-3% of the soil mineral N, whereas only a maximum of 0.01% of mustard N was volatilised over 24 days. Soils sampled at different times in the season decomposed mustard at similar rates at stimulated low spring temperatures. Nitrification rate was reduced 5-fold more than the mineralisation rate at 8oC. Straw incorporation for seven years did not affect the subsequent recovery of 15N enriched fertiliser or of 15N from labelled straw, by oil seed rape. 15N labelled fertiliser contributed up to 63% of the winter barley N. The labelled barley straw subsequently contributed 16% of the oil seed rape N in the absence of any applied fertiliser. Ploughing in straw in the autumn, in the absence of applied fertiliser had no yield penalty or effect on crop uptake, and may retain more mineral N in the upper soil layers, lessening the risk of leaching over the winter period. The results obtained here emphasise the importance of additions of organic materials to soil in supplying plant nutrients and minimising nutrient losses.

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 17, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Thesis advisor: Dr. Reid Smeda. Includes bibliographical references.

No description available.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1954. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1949. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 43-45).

Mode of access: Internet via World Wide Web. Available at http://hdl.handle.net/1947/9668. / "October 2008" Title from PDF cover (viewed on 25 September, 2009) Includes bibliographical references.

Inaug.-diss.--Göttingen. / Lebenslauf.

H. incana is a native species of the Mediterranean and Middle East. As a neophyte (alien) it has undergone a large range expansion in Northern Europe, the Americas, Asia and Australasia. Casual field observations suggested that within its native range, the dominant life strategy of H.incana was annual, whereas in the British flora it was predominantly perennial. Populations from native and alien ranges were studied in the field and in common garden experiments. Phenotypic differences in morphological and physiological characteristics were compared. Plants derived from neophyte British populations made larger leaf rosettes, flowered later (> 140 days) and exhibited a perennial life cycle. Plants from native. North African and Southern European populations (excepting those from montane Spain) made smaller rosettes, flowered early (< 110 days) and died after flowering once. Neophyte populations from California were similar to native populations. Some native populations (e.g. Cypress) did not survive a British winter. Unlike native populations, initiation of flowering in neophyte British populations was stimulated by a period of vernalisation. These results suggest that life strategy changes have occurred in neophyte populations of H. incana as this species expanded its range northwards, and implies possible genetic differences. Ten microsatellite primers, previously described for related Brassicaceae species, were therefore investigated for potential use in the assessment of H. incana population genetic structure. Five primers successfully amplified a product of expected size, of which 3 were subscequently sequenced to confirm the presence of the SSR. The application of real-time PCR DNA melting analysis to identify SSR variation was investigated using Roche SYBR green and Corbett HRM platforms. SSR variation could be detected using DNA melt analysis, but due to difficulty identifying the composition of heterozygous SSR's the technique could not be sufficiently refined to investigate population diversity. However, preliminary results indicated possible SSR variation between isolated populations.

No description available.