The aim of this work was to investigate the effect of soil properties on soil iodine dynamics and uptake to plants. Soil and vegetation samples were collected from across eastern Northern Ireland (NI) to form the basis of most experimental work; samples from the Rothamsted Park Grass archive were used to investigate the role of changing soil chemistry through time and due to selected fertiliser applications; and iodine dynamics in humic acid (HA) were studied to improve understanding of the role of organic matter in soils. Input of iodine in rainfall was considered in the context of samples from both locations, and the additional influences of coastal proximity, soil type and underlying geology were reviewed for the NI samples. Total iodine analysis was carried out using extraction with TMAH and quantification by ICP-MS; aqueous iodine speciation was determined using HPLC and SEC coupled with ICP-MS. The most important iodine inputs to both soil and vegetation were found to be directly from the sea in coastally-exposed locations, and from rainfall in other cases. Soil organic matter (measured as soil organic carbon, SOC) was determined to be involved in both retaining a portion of recalcitrant iodine in soil and HA, and in promoting sorption of both iodide and iodate in highly organic soils. Metal oxides (Fe, Mn and Al) were found to be important in rapid sorption of iodate to soils with SOC ≤ 38 %, and there was an indication that they may be involved in promoting the reaction of iodide with organic matter. Replenishment of a transient phyto-available pool was essential for provision of iodine to vegetation. The availability of recently added iodine (as 129IO3-) in the pot experiment was controlled by its sorption onto the solid phase, and near-constant input from irrigation water was the major source of vegetation iodine in most cases. Rainfall was shown to be important in controlling vegetation iodine concentrations in field situations. In soils collected from very coastally-exposed locations, the soil iodine concentration was extremely high and therefore a greater proportion of labile native iodine was available for uptake; irrigation sources were much less important. This work improves understanding of soil iodine dynamics and the important factors controlling iodine speciation and availability to plants. Results can be used to inform practices regarding provision of iodine to crops for both humans and grazing animals.

Conservation tillage is generally considered as an important component of sustainable agriculture. The benefits of conservation tillage have been presented as reducing runoff, enhancing water retention and preventing soil erosion. There is also general agreement that it can be used to conserve and enhance soil organic carbon levels to some extent. However, its applicability in mitigating climate change has been extensively debated, especially when the whole profile of carbon in soil is considered along with a reported risk of enhanced N2O emissions under conservation tillage. The suitability of conservation tillage in mitigating climate change and enhancing carbon sequestration is addressed in this research in an integrated approach combining characterisation of the soil porous architecture and other chemical and biological properties. Novel analytical tools such as X-ray Computed Tomography were used to characterise the 3-D soil pore network under conservation tillage for the first time. The study indicated zero tilled soils had a lower net emission of greenhouse gases on a CO2 equivalent basis indicating potentially zero tillage can be used to mitigate climate change. The net global warming potential under conventional tillage was 20% higher than zero tilled soil. A model developed to predict the greenhouse gas emissions from soil found that soil pore characteristics such as porosity played a significant role in the emission of greenhouse gases such as CO2 and CH4 among other factors such as microbial biomass carbon, bulk density and shear strength. Soil porosity alone accounted for 39.7% of the total variation for CO2 flux which was larger than any other parameter including microbial biomass carbon and soil carbon. Soil pore characteristics were revealed as one of the important determinant in aiding the GHG flux in soil. However N2O emission from soil was mainly dependent on soil moisture, microbial biomass carbon and microbial biomass nitrogen. It was also found that zero tilled soils contained 9% more soil carbon and 30% higher microbial biomass carbon than the tilled soil. It was found that tillage mediated aggregate changes could bring changes in carbon storage in soil depending on texture of soil. Increased microbial activity was evident at zero tilled soils as observed from the increased activities of hydrolysing and oxidising enzymes. The preservation of aromatic structures during residue decomposition might have contributed to enhanced sequestration of carbon under zero tilled soils as revealed by the FTIR data. The study indicates that soil management practices strongly influence other properties and by making a suitable choice of the tillage system, a comparative reduction in greenhouse gas emissions could be achieved at the same time enhancing sequestration of carbon.

An evaluation of the effectiveness of a training course is very difficult to implement, but it is necessary if the course is to achieve the objectives set out by the course designers. When the participants have completed their training, they should be equipped with the knowledge of the latest developments in their discipline, the skills to be able to put them into practice and the attitude to utilise this training experience to the full in the farm or unit situation. This study assesses the techniques available for evaluation and has selected one method of appraising Adult Short Courses, designed specifically for experienced agriculturalists from a particular farm discipline. The Agricultural Training Group Officer established the training needs of group members and organised a programme based at a central location and staffed by A. T. B. or external instructors. A questionnaire was administered to the population of course attenders at the end of each training day. The levels of knowledge, skills and attitudes were measured using a range of question designs and rating scales. The "before" level was valued at the same time as the "after" score. This is a departure from the more commonly used Pretest, Posttest design. Unit or farm physical performance data, related to stockperson control, was collected over the relevant years. A commercial psychological test was also used to evaluate the trainability of the course attenders. A comparative group of experienced agriculturalists, who were not involved in any A. T. B. training related to their unit attachment, were contacted to provide similar information and reduce any maturation, historical and local errors. The data collected showed significant increases in knowledge, skills and attitude levels with some degree of improvement in unit physical performance. The correlations between the objective criteria, unit physical data, and the subjective criteria, self-assessment ratings, were very mixed for the course attenders. The psychological tests tended to support independent unit manager valuations of the trainees. The training courses were effective and the evaluation has shown that trained staff can improve unit physical performance. The analysis supported the methodologies employed and further testing, with some modifications, using a larger population involved in a range of farm disciplines would be useful.

The use of peri-urban fenlands for agriculture usmg urban waste as manorial treatments is increasingly common worldwide, particularly in developing countries. The risk to human health from the use of these contaminated materials for crop production has been studied using two historically contaminated fenlands in NW England. The GBASE survey carried out by the British Geological Survey identified two areas of metal contaminated fenland; west of Manchester (Chat Moss) and north of Liverpool (Halsall Moss). The two areas are used for arable agriculture, and current demand for locally sourced food is increasing pressure on farmers to move to vegetable horticulture. The effect of the metal contamination on the soils and crops is of key importance to monitor any risk to the food chain. Historical research identified the two mossland areas as contaminated with urban wastes, Halsall Moss contaminated with urban organic wastes such as manure and Chat Moss contaminated with urban organic and mineral wastes. Waste disposal on Chat Moss was carried out by the Manchester Corporation to dispose of city waste and generate farmland from the peat. During the drainage up to 1.92 Mt of waste was incorporated into the soil, representing 38% of the topsoil today. Profiles of contaminated and control sites on Chat Moss and a contaminated site on Halsall Moss were collected, with pH, organic matter content and trace metal content measured. Trace metal content was elevated over subsoil levels in the topsoil of all sites, for example arsenic showed topsoil concentrations of 45 mg kg-I in the most contaminated site (CM-3) compared to 3 mg kg-I in the subsoil. The elevation of trace metals in the historically uncontaminated sites indicated possible atmospheric deposition of metals at the control site. Contamination levels were found to be less than originally identified in the GBASE survey, possibly due to differing sample preparation methods and survey size. The GBASE survey measured an average lead concentration in contaminated sites of 1985 mg kg-I compared to 378 mg kg-I measured by the current study. Arsenic and cadmium concentrations exceeded Soil Guideline Values in the most contaminated site, 43 mg kg-I and 1.8 mg kg-I respectively, but all other metals were within guideline limits. Halsall Moss was found to be less contaminated than Chat Moss, due to the mainly organic nature of the waste disposed at Halsall Moss. The mobility and fractionation of the contamination at the most contaminated site on Chat Moss were studied to understand the behaviour of the metals and assess potential risk to ecological or human health. Using sequential extractions, most metals were identified as hosted by organic, Fe/Mn oxide or residual phases. There was no difference observed in fractionation between control and contaminated sites, indicating that soil properties such as organic matter and Fe/Mn oxide content were more important in controlling fractionation than the source of metals. A comparison of Chat Moss with three soils of known contamination history also identified soil properties as key in controlling fractionation. Lability of Pb in the contaminated Chat Moss soil was assessed using 204Pb stable isotope dilution, it was found that 65% of lead was labile. This was the highest out of the four soils studied, and again most likely controlled by soil properties such as organic matter content and pH. The impact of flooding events on the Chat Moss soils was assessed, and it was found that under redox conditions of -200 mY, large quantities of arsenic, lead, molybdenum and manganese were released to soil solution, and drinking water limits for these metals were violated, for example As solution concentration reached 308 J.1g L-1 and the drinking water limit is 10 Ilg L-1. Environmental quality standards for freshwater were also violated by arsenic, copper, lead and zinc showing potential ecological hazard under these reducing conditions, with lead concentrations reaching 137 J.1g L-1 in contrast to the environmental quality standard of 4 - 20 J.1g L-1. The effect of soil contamination on vegetables grown on Chat Moss was also investigated, EU limits for Cd were exceeded by lettuce and onion, and EU limits for Pb were exceeded by parsley, carrot, radish and onion. Hazard Quotients used to assess the impact of plant contamination in the context of human intake showed that only cadmium and molybdenum were potentially hazardous. Thus it is not recommended to grow lettuce (high Cd), parsley, cabbage, radish and onion (all high molybdenum) at contaminated sites on Chat Moss. To minimise risk, conducting liming to raise the pH and immobilise the metals could be used, and careful selection of cultivars that do not accumulate metals is recommended.

The principal aim of this investigation was to understand the transformation and reaction kinetics of iodide and iodate added to soil in relation to soil properties. In addition, to integrate the data into a predictive model of iodide and iodate sorption kinetics parameterised by soil properties. Solid phase fractionation coupled with solution phase speciation (HPLC-ICPMS) was used to follow the assimilation of 129I- and 129IO3- spikes into ‘steady state’ soil microcosms. The extraction efficiency of tetra-methyl ammonium hydroxide (TMAH) for soil iodine, and the effects of experimental procedures and conditions on the speciation of extracted iodine were tested. Moreover, the possibility of extracting ‘reactive’ inorganic iodine forms sorbed on soil metal oxides by competition with PO43- ions was investigated. Results showed that changing TMAH concentration, extraction time, extraction temperature or soil particle size did not generally affect the concentrations of total iodine extracted. The ratio of iodide to total iodine in the TMAH extracts varied with the extraction conditions which led to the conclusion that part, or all, of the measured iodide is possibly produced by hydrolysis of organic iodine forms. This conclusion was also confirmed by the detection of high concentrations of iodide in TMAH extracts of a humic acid. Only iodide was measured in the phosphate extracts of soil and it constituted up to 33% of the total iodine in the KH2PO4 extracts which indicates that most of the iodine mobilised by KH2PO4 is organically bound. When soil / KH2PO4 suspensions were spiked with 129I- and 129IO3-, at least 50% of 129I- and 15% of 129IO3- were recoverable after 72 hours of reaction. The lowest recoveries were observed with the highest concentration of KH2PO4, which also mobilised the greatest concentrations of DOC, indicating that although KH2PO4 is capable of releasing sorbed iodide and iodate in soil, it may also promote iodide and iodate reaction with soil organic matter. Iodine content of soil biomass was determined following chloroform fumigation of soil. The concentrations of total iodine in fumigated soil samples were only marginally higher than iodine concentration in the control samples indicating that microbial biomass iodine constitutes only a small fraction of total soil iodine (0.01 – 0.25 %). The change in iodine (129I) solubility and speciation in nine soils with contrasting properties (pH, Fe/Mn oxides, organic carbon and iodine contents), incubated for nine months at 10oC and 20oC, was also investigated. The rate of 129I sorption was greater in soils with large organic carbon contents, low pH and at higher temperatures. Loss of iodide (129I-) from solution was extremely rapid, apparently reaching completion over minutes-hours; iodate (IO3-) loss from solution was slower, typically occurring over hours-days. In all soils an apparently instantaneous sorption reaction was followed by a slower sorption process for IO3-. For iodide a faster overall reaction meant that discrimination between the two processes was less clear. Instantaneous sorption of IO3- was greater in soils with high Fe/Mn oxide content, low pH and low organic content, whereas the rate of time dependent sorption was greatest in soils with higher organic contents. Phosphate extraction (0.15 M KH2PO4) of soils, ~100 h after 129I spike addition, indicated that concentrations of sorbed inorganic iodine (129I) were very low in all soils suggesting that inorganic iodine adsorption onto oxide phases has little impact on the rate of iodine assimilation into humus. Transformation kinetics of dissolved inorganic 129IO3- and 129I- to sorbed organic forms was modelled using a range of reaction and diffusion based approaches. Irreversible and reversible first order kinetic models, and a spherical diffusion model, adequately described the kinetics of both IO3- and I- loss from the soil solution but required inclusion of a distribution coefficient (Kd) to allow for instantaneous adsorption. A spherical diffusion model was also collectively parameterised for all the soils studied by using pH, soil organic carbon concentration and combined Fe + Mn oxide content as determinants of the model parameters (Kd and D/r2). From the temperature-dependence of the sorption data the activation energy (Ea) for 129IO3- transformation to organic forms was estimated to be ~43 kJ mol-1 suggesting a reaction mechanism slower than pore diffusion or physical adsorption, but faster than most surface reactions.

The present thesis concerns large covariance matrix estimation via composite minimization under the assumption of low rank plus sparse structure. Existing methods like POET (Principal Orthogonal complEment Thresholding) perform estimation by extracting principal components and then applying a soft thresholding algorithm. In contrast, our method recovers the low rank plus sparse decomposition of the covariance matrix by least squares minimization under nuclear norm plus $l_1$ norm penalization. This non-smooth convex minimization procedure is based on semidefinite programming and subdifferential methods, resulting in two separable problems solved by a singular value thresholding plus soft thresholding algorithm. The most recent estimator in literature is called LOREC (Low Rank and sparsE Covariance estimator) and provides non-asymptotic error rates as well as identifiability conditions in the context of algebraic geometry. Our work shows that the unshrinkage of the estimated eigenvalues of the low rank component improves the performance of LOREC considerably. The same method also recovers covariance structures with very spiked latent eigenvalues like in the POET setting, thus overcoming the necessary condition $p\leq n$. In addition, it is proved that our method recovers structures with intermediate degrees of spikiness, obtaining a loss which is bounded accordingly. Then, an ad hoc model selection criterion which detects the optimal point in terms of composite penalty is proposed. Empirical results coming from a wide original simulation study where various low rank plus sparse settings are simulated according to different parameter values are described outlining in detail the improvements upon existing methods. Two real data-sets are finally explored highlighting the usefulness of our method in practical applications.

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A careful examination of the creative writing of T. S. Eliot reveals that his poetry can be divided for purposed of consideration into two phases. The first phase refers to those poems written up to and including "The Hollow Men". These early poems can best be grouped together and characterized by the term frustration. The poetry of the second phase, written after "The Hollow Man," is dominated by and best considered in regard to a quest for the ideal.

There are many vegetable fruits recognized in Nigeria, but tomato, a vegetable fruit is a major food component, an ingredient utilized by every house hold and constitutes the national food security programme. The record confirmed that Nigeria produces approximately 1.8 million metric tons of fresh fruits for domestic consumption, with national demand of about 2-3 million tons per annum with a demand gap of about 500,000 metric tons. Tomato production is an important source of income to farmers unfortunately diseases such as Alternaria alternata greatly increase food losses by an approximately 20-30% and methods of using synthetic chemical compounds can be costly and dangerous if applied by an unskilled operator and are often not available at the time when required. As a result this study focused on the effect of hot water dipping as a non-chemical method to control the black mould disease caused by Alternaria alternata on red tomatoes. Hot water dip at 50ᴼC for 5 or 10 min was carried out on Alternaria alternata spore suspension (in-vitro), the results showed a significant (P≤0.05) reduction in germination of spores after 48 h. The in-vivo hot water treatment was carried out in three groups, viz-a-viz; first group consists of 30 and 50⁰C and tomato fruits were heated in hot water for 30 and 60 min respectively. The second group was 30, 40 and 50⁰C and fruits were dipped in hot water for 20 min. In the third group the temp was at 40, 45 and 500C and fruit were dipped in hot water at these temperatures respectively for 10 min. Furthermore, the hot water temp was increased to 50 and 55⁰C and inoculated fruits were immersed for 5 min in separate hot water bath. In this trial the result showed that dipping artificially inoculated fruit at 50 or 55⁰C for 5 min significantly reduced (P≤0.05) decay development caused by A. alternata. Conidia germination was more sensitive than mycelia growth to 50⁰C, but inhibition of both processes increased with the duration of time of treatment. The in-vitro hot water treatment of Alternaria alternata spores at 50⁰C i for 30 min significantly reduced the spore germination and mycelia elongation of the fungal pathogen in 48 h. The in-vitro result obtained was attributed to the direct effect of heat on the spore germination as well as mycelia growth resulting in the reduction of the growth of the fungus on the inoculated red fruit. Splitting was observed on the pericarp (skin) at the point of inoculation of fruits before hot water treatment at 55°C for 5 min. The hot water treatment of the tomatoes had the following effects on the attributes of quality: the Brix degrees measurement showed a negligible difference in 40 °C or 50°C compared with the control for 30 min heat treatment after 24 h storage. Also there was no effect of heat on the total soluble solid likewise, the firmness measurement on flesh of tomato showed no significant difference when compared with the control. In this study the change in colour after heat treatment was not statistically significant. Similarly, in the taste test there appears no real difference recorded in the attributes of juiciness, flavour and overall acceptance except that the skin of the tomato was recorded “softer” by some of the taste panellists. This study has shown that prestorage hot water treatment may be a useful non-chemical method of controlling A. alternata postharvest disease pathogen without adverse consequence on the fruit quality.

To meet the rapid growth of the global population and the expected demand for food, significant enhancements in yields are needed, together with optimised N fertilisation and environmental issues, particularly in the production of major grain crops, such as wheat and rice. Improving photosynthesis, together with NUE, has been considered an unexploited opportunity in the research on improving crop yields. Therefore, transgenic wheat plants with increased SBPase activity showed an improved photosynthetic leaf rate and total biomass production. The Rubisco protein is a major N investment in crops, but it has also been exhibited that under some environmental conditions, there may be an excess of Rubisco greater than that needed to maintain photosynthesis. This raises the question of whether a small reduction in the amount of the Rubisco enzyme can be used to improve NUE without any negative effects on plant yield. To address the question, wheat plants with decreased Rubisco were produced. Physiological studies were performed on five independent transgenic lines with different levels of Rubisco, and the photosynthetic rates, biomass and grain yields were determined. Rubisco RNAi lines with reductions in the Rubisco protein of more than 40% showed a significant decrease in photosynthesis, growth and grain yield. Interestingly, the plants with the lowest level of Rubisco activity had significantly higher levels of leaf and seed N when compared to WT plants. In contrast, small reductions in the Rubisco protein of between about 10% and 25% did not have an adverse effect on photosynthesis, growth or grain yield in two independent transgenic wheat lines. Furthermore, to search for new promoters to drive good transgene expressions specialised to wheat leaves, two Brachypodium promoters, SBPase and FBPA, were cloned upstream of the GUS fusion gene and transformed into wheat leaves. Consequently, both promoters resulted in detectable GUS expression in wheat leaves at different growth stages and did not show expressions in the roots.