Although current environmental policies may prove successful against narrowly defined criteria of economic, social or environmental sustainability, it is by no means certain that the sustainability of inter-dependent economic and environmental systems will be assured. In fact, policy intervention may result in the displacement of environmental problems to other media, times or places. Farmers are the focus for divergent forces of state, market and social regulation and in consequence their response, or more importantly non-response, to environmental policies cannot be assessed in isolation. This thesis explores these complex issues through analysis of the agriculture-water interface, focusing on the allocation and regulation of abstraction water for use as spray irrigation by farmers in the eastern counties of England. Adopting an interface-network methodology, the analysis traces the network of social relations which directly and indirectly influence the use and management of irrigation water and potential response to demand management policies, encompassing farmers' interaction with the NRA, food processing, manufacturing and retail firms as well as farmer representative groups. Risk and uncertainty play a central role shaping interaction not only between firms, but between firms and farmers as they attempt to reallocate the financial, production, legal and environmental risks associated with production. The analysis demonstrates how farmers' incorporation into the "quality projects" of the downstream food network critically distorts their response to demand management policies. This perpetuates a highly intensive system of agricultural production, contributing to the loss of landscape and wildlife habitat and diffuse pollution of ground and surface water sources. The analysis concludes by outlining an alternative agenda of action for the Environment Agency which focuses on promoting synergy between state and market forces of regulation. Only through addressing these issues will the integration of the environment and economy prove successful at the agriculture-water interface.

This study of the irrigation and drainage systems in Basrah province analyses the factors affecting these systems, such as the water resources, soil conditions, management and crops and then shows the effects of these systems on crop yields and soil salinity. In such a study it is necessary to discuss the physical characteristics of the province and the hydraulic aspects of Iraq which have direct and indirect influences on the irrigation and drainage systems in the province. In accordance with the variations in the irrigation and drainage systems, the province has been divided into four regions, namely : the Western, Southern Tigris, marshes and the Shat Al-Arab. One of the findings of this study has been the spatial differences between the levels of salinity in the irrigation water which ranges from moderate in the southern Tigris, marshes and the upper section of the Shat Al-Arab to excessive in the western region and the lower section of the Shat Al-Arab. The salinity of the irrigated soils has also been shown to vary from region to region, from a very low level in the marshes to a strongly high level in the southern Tigris. Throughout the province it was found that the farmers continued to rely on their traditional skills and inherited experiences in carrying out cultivation and irrigation operations which have resulted in over-irrigation and low efficiency of use of irrigation water. This, together with the inadequate drainage and high evaporation rates has led to exacerbation of the soil salinity problem and the consequent abandonment of large areas of cultivable lands in the western, southern Tigris and the Shat Al-Arab regions. Additionally, in the marshes and the Shat Al-Arab regions the presence of aquatic vegetation forms an important obstacle to irrigation and drainage operations. Moreover, it is likely that in the future the province will face a serious shortfall in irrigation water availability. The province, however, still remains an important agricultural area, providing the Iraqi markets with tomatoes during winters and contributing 11.8% of the country's total date production. Improvements in irrigation and drainage and in soil-water management are therefore vital.

No description available.

No description available.

Existing date harvesting machines are vehicles equipped with a long arm to lift a man on a platform to harvest the fruits. The arm and the vehicle are heavy (4 to 8 tonnes), expensive (from £16 000) and are not sufficiently manoeuvrable in constricted date groves. Most dates in the main producing countries, including Iran, are therefore harvested manually. The manual method is unsafe, slow, expensive (£0.63 per tree) and the fruit quality is often damaged. A light, weight 4 wheel drive, remotely controlled tree climbing machine is, therefore, a potential solution to the problems of harvesting and servicing (such as pollinating and pruning). A prototype of such a device was designed, developed and evaluated under laboratory conditions. To determine the operating characteristics and feasibility the machine was designed to climb the tree using pneumatic tyres as traction wheels. The machine can be transformed to ground drive and move between trees under its own power. This approach reduces the machine weight, cost and size because the tree trunk is used as a support for the machine to climb to the fruits. It is operated and controlled from the ground which improves the operator safety. A vertical traction theory for this type of machine has been developed based on the tree size and surface characteristics and machine size and weight which can be used to design date harvesting and climbing machines with different capacities. The test results showed that the experimental machine could achieve a tractive efficiency of 90% and that the optimum wheel slippage was between 10 - 15%. The machine consumes a maximum of 1.4 kW power which is only 3% of the power requirement of existing systems. The machine weight is 150 kg which is 2- 4% of the existing systems' weight. It is capable of climbing the tree at a maximum speed of 0.27 m/s although the optimum speed is 0.17 m/s for best control. The prototype can carry a payload of 100 kg of dates and, considering a field efficiency of 75%, it can potentially harvest a tree in 22 minutes which is 18 % faster than the manual system in Iran and 6% faster than one of the mechanised systems used in Saudi Arabia. The harvester can work on tree diameter ranges from 300 to 850 mm and can pass over the tree leaf bases of 41 mm high. The machine should not damage the tree because the tree resists the machine stresses with a minimum safety factor of 7. An economic analysis showed that it can be manufactured in Iran at 20 % of the cost of existing systems. The machine cost per tree is equal to the hand harvesting method (£O. 63 per tree) for Iranian farmers if it harvests 978 trees per year.

The contribution by the water table to crop water use was evaluated in the absence of surface water application from lysimetric studies in a glassliouse during 1988, 1989 and 1990. The water table contribution was measured for beans, barley and lettuce in the presence of constant water tables 60, 90 and 120 cm deep. The water table contributed to about 27.0, 16.4 and 11.4% of evapotranspiration of barley with water tables 60, 90 and 120 cm deep, respectively. The contribution in lettuce was found to be 34.7, 13.5 and 6.0% for the 60, 90 and 120 cm water tables, respectively. The water table could not contribute to the evapotranspiration of beans because the initial soil moisture suction profile was not in equilibrium, and there was always a zero-flux plane above the water table. Capillary upward flux from the water table was also measured using Darcy's equation and by direct measurement. For this, unsaturated hydraulic conductivity was determined in the laboratory from diffusivity over a wide range of moisture content. Conductivity values were also evaluated in situ using Darcy's equation. In situ and laboratory conductivity values were well fitted by Gardner's (1958) conductivity function but not by that of Rijtema (1965). Root water uptake was evaluated using the extraction-term approach. A very small proportion of roots near the water table was absorbing water from the capillary fringe iii the case of a deep-rooted crop (barley) for all water table depths. Lettuce, a shal1ow-rootd crop, was absorbing water from the water table although roots were confined to the top 5 cm depth for all water table depths. A simulation model (CAPROW) was developed to account for capillary rise from constant water tables. The model can also predict soil moisture content, root water uptake and inflow to roots provided soil physical parameters and relevent data are known. Parameters needed to run the model were determined from the bean experiment with the water table at 60 cm depth. CAPROW was used to simulate results for water tables at 90 and 120 cm under three different crops. Model predictions of soil moisture contents at harvest agreed well with the measured values. The predicted cumulative upward flux in barley and lettuce under two different water table treatments agreed closely with the measured values. The contribution by the water table to water use by barley was found to be 16.4 and 11.4% for 90 and 120 cm water table depths, respectively. Corresponding simulated values were 15.5 and 10.4%. For lettuce, measured contributions from the water table to evapotranspiration were 13.5 and 6.0%. Corresponding simulated values were 15.7 and 6.7%.

In recent years the importance and the lack of comprehensive methodologies for measuring the performance of existing irrigation schemes has been widely expressed. The objective of this study is to develop a systematic procedure by which some use can be made of the large quantities of data, already routinely collected in irrigation schemes, for the purpose of their regular seasonal evaluation. Consideration is confined to the performance of the main irrigation system of small-holder, canal-fed irrigation schemes of the developing countries. A generalized conceptual framework has been developed for a methodology by which the performance criteria for any irrigation system can be identified and combined together into a single index which measures the overall performance of the system. Six criteria have been identified as adequate for characterizing the important features of the performance of any irrigation system. These are; adequacy, equity, water losses, water user convenience, cost and durability. New methods for characterizing each of adequacy, equity and water user convenience have been developed and tested using data from the Gezira scheme, Sudan. Characterization of adequacy, equity and water losses involves the development of a soil moisture simulation model and characterization of the water user convenience involves the use of the concept of the fuzzy set theory. Identification of the criteria to be used in evaluating any particular system(s) and evaluating the trade-offs between them requires the participation of the decision-maker in the system(s) to be evaluated. This is achieved through the use of the multi-attribute utility theory. It has been applied with a group of Sudanese officials in order to derive their utility functions. The utility function reflects the decision-maker's strength of preferences over different achievement levels of each objective and his trade-offs between different objectives. The derived utility functions are reported and their usefulness is discussed. The methodology developed provides a useful tool for measuring the performance of irrigation systems, comparing the performance of different systems and assessing improvement in performance resulting from rehabilitation investments.

The proportions of the Critical State surfaces of a given soil depend on its stress and moisture history, its current moisture status and soil type. The influence of these factors on the geometry of the state surfaces, and their bearing on the mechanical behaviour of the soil itself, cannot be readily perceived because of the very large number of interacting effects present in the model. The use of sophisticated computer graphics for the three-dimensional visualization of critical state surfaces would therefore provide a ready means for obtaining an insight into the complex changes taking place in critical state space. The initial part of the thesis deals with the formulation of mathematical models and computer software for integrating numerical computations, data reduction and visualization techniques for analysing critical state surfaces. The programmes developed were used for interpreting the influence of moisture status on the key behavioural patterns of three different British Soils. Systematic changes to state space due to the combined influence of moisture content variations and soil type were readily traced. It is well known that collating data for the above analysis is difficult and requires advanced measuring techniques. An attempt was therefore made to establish a connection between the data obtained from a simple field measuring device, such as a cone penetrometer, with the volume-change behaviour of soil, as modelled by its critical state surfaces. This is attempted in two stages. The first stage presented in the thesis assumes the soil to be a rigid-plastic Mohr-Coulomb material and deals with the formulation of a mathematical model to predict cone index as a function of cone geometry, penetration depth, c, cp and soil-to-metal parameters cQ and S. This model is based on the extension of the basic two-dimensional Sokolovski solution to the three-dimensional slip-line field developed during the deep penetration phase of a cone. Shallow penetration depths, at which the standard Sokolovski rupture surface interacts with the soil surface, cannot be dealt with by this approach. The second stage of the investigation attempts to connect cone index with the stress (p, q) and pore space (v) parameters of the soil on the cone surface. The model developed in the thesis is based on identifying a state parameter yr (defined by Been and Jefferies for dry sands). This establishes the position, within critical state space, of the cone surface stress and pore space parameter (p, q and v) relative to the critical state wall. The state parameter yr is then associated with soil type and moisture 2 content by a two-parameter linear function. Once these two parameters are found experimentally, cone index can be readily translated into pore-space estimates. The thesis presents the mathematical analysis which provides the basis for this correlation. The thesis describes the experimental investigations carried out to verify the performance of the theoretical models developed. The validation of the state parameter concept required the design and development of a special calibration chamber which could apply controlled boundary stresses to a cylindrical soil sample into which the penetrometer is advanced. Ideally very large sample diameters are required to minimise boundary interference, but a compromise had to be made by using miniature penetrometers and a realistic sample diameter of 100 mm. The cone penetrometer performance model was tested under laboratory conditions in an indoor soil tank. Both these investigations required tedious back-up laboratory experimentation to establish the basic Mohr-Coulomb and critical state parameters of the test soil over a wide range of moisture contents. All the soils were dealt with in a remoulded state as consistently reproducible stress and moisture histories for this case can be easily maintained in each of the very large number of samples required in the experimental programmes. The experimental work shows very clearly that the state parameter concept is applicable to partly saturated c-Sp soils over a wide range of moisture contents and that it is possible to quantify the systematic changes in the state parameter y' with soil moisture content. The predictive performance of the cone penetrometer model, within the specified penetration range, was also good. Data reduction charts for interlinking these two models are presented and the use of these charts for the derivation of pore space particulars from cone index data predicted satisfactory trends. However, this procedure appears to over-predict dry bulk density by a considerable margin. The validation presented in this study is for a single sandy loam soil. Even though the overall predictive performance of the mathematical models in this particular soil is most encouraging, it should be borne in mind that the models developed are bound to be influenced by the drastic simplifications required to interlink two disparate models, one which ignores volume change with one which does not. Further work is required to remove any detrimental consequences of these compromises and to introduce confidence in extending the findings to other soil types.

Earlier research reported in the literature of plastic extrusion pointed out the surperiority of a tapered screw for developing high pressure in a short barrel. But the conveying process in the tapered screw and how pressure was generated were not explained. This work is intended to provide a thorough understanding of the conveying and compaction processes by a tapered screw. A complete theory of the performance of a tapered screw conveyor was developed, based on the conventional approach which assumes 'plug flow' , but with the following two modifications: the compressibility of the material was taken into account by using a pressure /density relationship which makes it possible to simulate the density change with pressure during compaction. ii. the effect of the slip of material along the screw channel wall was taken into account in the analysis by using a slip factor Po, which modifies the down channel velocity. Slip, by reducing the down channel velocity, leads to a reduction in the axial velocity and the mass flow rate of the extruder at any speed of rotation. The resulting equations express the relationship between the performances of the tapered screw (mass flow rate and pressure build up) and the screw geometries and frictional conditions. A one dimensional differential equation obtained for the pressure build up indicates that low friction between the material and the screw, and high friction between the material and the barrel can help the pressure generation process. A method measuring accurately the coefficients of friction between the material to be compacted and both the screw and the barrel is proposed. An experimental rig was designed and developed to measure the pressure in a tapered screw conveyor for different mass flow rates at four speeds of revolution in order to confirm the theory. A proposal is made for a better design of inlet to a screw conveyor. Comparisons were made between tapered and standard screw extruders with the same length, which show that the tapered screw is capable of generating a much higher pressure than the standard screw under the same operationing conditions. The experimental results indicate that the predicted pressures agree well with the measured ones.

High demand for energy and increasingly expensive petroleum prices led to development of new alternative fuels for transportation, such as bio-ethanol and bio-diesel. Even though a cost reduction in the production of cellulolytic enzymes is occurring, the conversion of plant cellulose into sugars still remains an expensive and slow process. Pretreatment of lignocellulose materials to remove lignin and alter physical/chemical structures significantly improves hydrolysis of cellulose to give high yield of sugars. In this study, ultrasonic pretreatment of energy cane bagasse was used in the presence of ammonia (NH4OH) to enhance the saccharification process by separating lignin, cellulose and hemicellulose from each other in biomass. The process performance was investigated as a function of low ultrasonic frequency (20, 20.5, 21 kHz) at a power level of 100 W for the reaction time of 30 min at 80 to 90°C reaction temperature. The pretreatment was performed for four different combination mixtures:(1) energy cane bagasse with 28% NH4OH and water at a ratio of 1:0.5:8 (w:w:w) and processed immediately, (2) energy cane with water at a ratio of 1:8.5 (no ammonia) and processed immediately, (3) energy cane soaked with 28% NH4OH and water with the same ratio for 3 hours, then drained and pretreated ultrasonically and (4) energy cane soaked with water with the same ratio for 3 hours (no ammonia), then drained and pretreated ultrasonically. Composition analyses were performed after pretreatment to quantify glucose yield and lignin removal rates. Enzymatic hydrolysis tests were also performed to quantify the sugar yield. Results for composition analysis for different pretreatment combinations were obtained against the control. The objective was to find the best frequency for which high glucan % and cellulose digestibility % for degrading them to simple sugars were obtained. The pretreatment process was performed again for all the four combination mixtures mentioned as a function of pretreatment reaction time (30, 45, 60 min) with constant frequency at 20 kHz, power level of 200 W and increase in reaction temperature of above 120 ° C. All the energy cane combination mixtures were pretreated along with their respective controls (without ultrasonic frequency). The cellulose digestibilities among various combination mixture samples based on a particular frequency were not statistically significant but varied significantly compared to the untreated energy cane bagasse. The energy cane bagasse with 28% NH4OH and water for 60 min reaction time obtained the highest cellulose digestibility of almost 44% for both non-soaked and soaked samples compared to 20.44% for the untreated energy cane bagasse (control). Energy cane bagasse with water for 60 min reaction time obtained cellulose digestibility of 34.14%, whereas the water soaked and drained sample for 60 min reaction time obtained cellulose digestibility of 38.12%. The maximum theoretical glucose yield was 24.29 g / 100 g of dry biomass for the combination mixture of energy cane bagasse with 28% NH4OH and water for 60 min reaction time. Theoretical glucose yield for energy cane bagasse with 28% NH4OH and water soaked and drained sample for 60 min reaction time was 23.99 g / 100 g of dry biomass, whereas the theoretical glucose yield for water (no ammonia) for 60 min reaction time was 10.07 g / 100 g of dry biomass. Theoretical glucose yield for water soaked and drained sample for 60 min reaction time was 10.91 g / 100 g of dry biomass. The results also indicated that pretreatment time and various combination mixtures were statistically significant at the 95% confidence interval for % glucose yield of pretreated energy cane bagasse. The pretreatment efficiency was also observed via increased porosity and fiber swelling of the treated energy cane fibers through Scanning Electron Microscopy (SEM). These results demonstrated that ultrasonic pretreatment along with NH4OH can be used as a potential pretreatment method for lignocellulosic biomass to produce biofuels.