12 research outputs found
Modeling subsurface drainage in Clermont silt loam using the finite element technique
No full textA finite element model was used to predict drain flow hydrographs and water table depths in an artificially drained Clermont silt loam soil. The field data were obtained from a drainage project at the Southeast Purdue Agricultural Center (SEPAC). Vertical and horizontal saturated hydraulic conductivities measured in 6 soil layers at 6 vertical sections showed a high spatial variability for that property and an anisotropic soil profile. The model incorporates rectangular and triangular linear elements; it uses two methods (influence coefficient and numerical integration) for calculating the element matrices; and two methods (Brooks and Corey and van Genuchten) for estimating the unsaturated hydraulic conductivity. The model also uses a finite difference technique to approximate the ordinary differential equation in time resulting from the finite element discretization of the spatial domain. The time is also automatically controlled. The simulated drain flow hydrographs for 5, 10 and 20 m drain spacings, predicted the shape of the measured hydrographs quite well. However, the model underestimated the peak flow in a dry year (1987) and overestimated the hydrographs in a wet year (1989). The predicted water table for the wet year was higher than the measured water table. Also, when deep seepage was included in the model, both the predicted water table depth and shape were in better agreement with the field conditions. A probabilistic method, the modified point estimate method, was combined with the finite element model to transfer the variability in the measured saturated hydraulic conductivity to the output of the model. The simulations showed that the flow velocities were more sensitive to the variability in conductivity than were the pressure potentials. While the large coefficients of variation for velocities occurred at the region far away from the drain where the velocities were low, the large coefficients of variation for pressure potentials occurred close to the drain tube. The coefficients of variation for the drain flow rates decreased as the water table depth increased for both 5 and 10 m drain spacings, but were lowest for the 5 m drain spacing. (Abstract shortened with permission of author.
Farmer participation in government commodity programs: A multiyear risk management analysis
No full textGovernment programs for agricultural commodities affect planting decisions and farm income for many producers. Many proposals to reduce federal expenditures are being considered for reform in the 1995 Farm Bill. In order to determine the effect of these proposals on both farmers and government, the producer's planting and participation behavior must be analyzed. This study determines the value to an individual farmer of participating in government programs in a stochastic, multiyear planning environment. It also determines how producer behavior might change if certain proposals for the 1995 Farm Bill are adopted.Stochastic elements are important because program participation and crop diversification may be substituted to manage risk. Multiyear planning is important because the ability to collect program benefits depends on dynamic planting decisions. The mathematical model uniquely combines a discrete stochastic program of uncertain ARP parameters and nested MOTAD submodels of intrayear variability. This new approach is the first known empirical study applying both risk- and variability-aversion coefficients in a multiyear model.Results indicate that government programs are very valuable to producers by both increasing income and reducing risk. Reducing target prices affects a cross section of Illinois farmers more equally than decreasing acres eligible for deficiency payments but penalizes them more to achieve the same effect on the federal budget. Variability aversion is important.Made available in DSpace on 2011-05-07T12:30:47Z (GMT). No. of bitstreams: 2
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The Determinants of Dairy Farming Competitiveness in Ukraine
No full textWTO accession and the expected free trade agreement with the EU pose significant challenges for Ukrainian agriculture, implying structural changes for the sector as well as adaptations at the farm level to improve efficiency and competitiveness. However, a recent study by von Cramon-Taubadel and Nivievskyi [2] demonstrates a clear lack of competitiveness. This directs attention to the forces that drive competitiveness in Ukrainian agriculture. Dairy farming deserves particular attention in this regard, since it is one of the main income generating sources for the rural population, and of raw material supply for the fast growing dairy processing. In this paper at first we analyze the profile of competitiveness of dairy farming in Ukraine, demonstrating that only about 20% of dairy farms produce at competitive level. Then using a fixed-effect panel regression we analyze the determinants of competitiveness in Ukrainian dairy farming. The size of the farm, productivity and labor intensity have a strong positive effect on competitiveness, while arable land per head has negative effect. Finally, total subsidies received by farms are found to have a negative impact on competitiveness, and this impact does not differ significantly between farms with different herd size.Dairy, Ukraine, Competitiveness, Livestock Production/Industries,
Risk management prospects for Egyptian cotton
No full textThe authors examine risk management options for Egyptian cottons, the export prices for which are volatile. They use regression analysis to establish whether Egyptian cotton's prices can be effectively hedged by using existing futures contracts on the New York Cotton Exchange. They find no relationship between the movements in prices of Egyptian long and extra-long cottons and prices for the base quality of U.S. medium staple cotton traded on the New York futures market. (Probably because Egyptian cotton prices are government-determined, U.S. medium staple cotton prices are influenced by price support policies unrelated to the longer staple markets, and the fiber of the cottons analyzed have different physical characteristics.) So, the New York cotton futures market's No. 2 contract is not an appropriate mechanism for hedging the price risk facing Egyptian cotton under present procedures for determining prices - and probably not under market-determined prices. If the cotton market in Egypt is liberalized, cotton prices there may correlate more with prices elsewhere - especially for the longer staple cottons. The authors extend their regression analysis to the prices of other medium staple cottons - Australian, Central Asian, Mexican, Pakistani, and Turkish - to determine how they behave relative to U.S. medium staple cotton prices. None of these prices had short-term movements closely related to U.S. cotton prices, indicating mainly the influence of domestic policies on the U.S. market. Again, the New York futures No. 2 contract does not provide a satisfactory hedge for these cottons. The cotton futures contract recently introduced in New York (world cotton contract) - based on the Cotlook A Index - may prove useful for hedging the price risk for some cottons (especially Australian, Central Asian, and Pakistani) but apparently not Egyptian cotton. The authors recommend (together with privatizing the industry) establishing a domestic spot market to give transparency to the price-forming process. When the spot market is functioning well, establishing a foward market could provide a hedging instrument for Egyptian cotton.Markets and Market Access,Crops&Crop Management Systems,Agricultural Research,Textiles, Apparel&Leather Industry,Access to Markets
COMPARING THE PROFITABILITY OF CASSAVA-BASED PRODUCTION SYSTEMS IN THREE WEST AFRICAN COUNTRIES: COTE D'IVOIRE, GHANA AND NIGERIA
No full textSub-Saharan Africa (SSA) cassava-producing countries such as Nigeria, Ghana, and Côte d'Ivoire have developed, in recent years, a renewed interest in cassava as an alternative food crop. This has led to a major expansion in cassava-based production systems in Nigeria and Ghana, whereas there has been a slower growth in Côte d'Ivoire (Nweke et al., 1998). This paper is based on the argument that the difference in various factors such as agricultural policies (i.e., trade and price policies, domestic production taxes or subsidies), location and technologies (production and processing) between Nigeria, Ghana and Côte d'Ivoire the difference in the level of growth in cassava-based production systems. The paper examines, using the Policy Analysis Matrix (PAM), the magnitude of the impact of these factors on the private and social profitability of cassava production and post-production processing in Côte d'Ivoire, Ghana and Nigeria. The topic has not been examined in previous studies. The paper relies primarily on data for Côte d'Ivoire, Ghana and Nigeria from the Collaborative Study of Cassava in Africa (COSCA) survey. The baseline results demonstrate the similarity in efficiencies of production in these West African countries. The simulation findings indicated that, in Côte d'Ivoire, farmers benefited from the depreciation of the equilibrium exchange rate while farmers in Ghana and Nigeria suffered losses. Simulation results also indicated that Ivorian and Ghanaian cassava/maize farmers could benefit from growing IITA's improved variety and adopting mechanized processing methods.Crop Production/Industries,
The Bioterrorism Act of the USA and international food trade: evaluating WTO conformity and effects on bilateral imports
No full textThe September 11th event focused the world’s attention on the threat of bioterrorism on the food chain. As a consequence, the USA implemented the Bioterrorism Act (BTA) containing new import requirements that can be classified as non-tariff barriers (NTBs). This paper analyses these NTBs by performing an assessment of WTO conformity and trade impact: hereby general problems in the analysis of bioterrorist risks are explored as for this new and unknown threat explicit WTO rules are still missing. Additionally, in exploring the BTA relevant process standard rules laid out by the WTO, the analysis indicates the extensive flexibility provided in this framework. This leads to larger scope for national polices on process standards compared to product standards (e.g. residua levels). The empirical trade flow analysis illustrates differences in the compliance costs between countries. This differentiation can be caused by learning costs that may differ among countries. The analysis highlights that perishable products and countries with small import quantities are mostly affected.food terrorism, non-tariff barriers, trade facilitation, Bioterrorism Act, international food trade, SPS Agreement, International Relations/Trade,
'Beyond, both the Old World, and the New': Authority and Knowledge in the works of Francis Bacon, with special reference to the New Atlantis
No full textPhDThis study investigates the role of authority in the works of Francis Bacon,
arguing that the issue of authority provides not only an interpretation of New
Atlantis, but an important structural component of his body of works. From
the first manifestation of his philosophical project to his last works of natural
history, authority is an all-pervasive issue - the authority of nature, of
scripture, of the named author, and how authority functions in the
dissemination of natural knowledge. Chapter one argues that the publication
of New Atlantis alongside Sylva sylvarum in 1626/7 was more the result of
William Rawley's need to assert his own authority as the protector and
disseminator of Bacon's textual legacy than an appreciation of the work's own
qualities. Chapter two considers Bacon's views of history and time,
suggesting that Bacon not only conceived of a new, progressive mode of
historical time which would allow for the assertion of a textual authority based
on the records of a civilisation unbroken by the vicissitudes of time, but that
he figured these theories in New Atlantis. Chapter three argues that Bacon
used theology both as defence and imperative to his intellectual programme,
while his attempt to move beyond the deterministic, Calvinist world-view to
allow for multiple possible futures, or `chance': Bacon could then present
experiment as the way of eliminating chance, in order to accelerate the rate of
new discovery. Chapter four investigates Bacon's manipulations of textual
authority, from the early rehearsals of the Instauratio magna to the
performance of reliability in print in Sylva sylvarum. Finally, the afterword
seeks to suggest that the New Atlantis hinges on the issues of authority with
which Bacon engaged throughout his career and writings: in the issue of
authority, Francis Bacon found the beginning and the end of his philosophy
Soil and Landscape Factors Affecting Phosphorus Loss from the Fitzgerald River Catchment in South West of Western Australia
No full textFollowing over 100 years of agriculture and continuous phosphorus (P) fertilizer application in the south west of Western Australia, there is a growing risk of P transport from cropping and pasture land to streams. However, soil and landscape factors affecting the likelihood of P losses and of stream water contamination have not yet been assessed for the South coast region of Western Australia. The present investigation was conducted in the Fitzgerald River catchment located ~ 400 km south east of Perth, to identify risk of P losses from agricultural land to streams, through an understanding of how P is retained within complex landscapes and released via surface and subsurface flow paths. The 104,000 ha catchment is in a moderately dissected landscape (average annual rainfall 450 mm) and discharges into the World Heritage listed Fitzgerald Biosphere. The main use of cleared land in the catchment is broad-scale agriculture, primarily winter grain cropping and pasture for livestock.
The aim of an initial study was to identify the areas with high soil P concentrations and their relationship to factors such as soil type, topography, management (e.g. fertilizer and manure inputs, and uptake by crops or forage) and how variations in soil P concentrations were related to soil physico-chemical properties, P fertilizer management and landscape position. A wide variation in P concentrations was observed across the catchment, but few of the samples exceeded Colwell extractable P levels of 30 mg/kg in the 0-10 cm layer which is regarded as a critical level for crop and pasture productivity. The western area of the catchment, which was cleared earlier (before 1966) than the eastern area had a greater prevalence of loam soils, and higher Colwell-extractable P concentrations (average)22 mg/kg vs. 13 mg P/kg) due to soil type effects and higher P accumulation over time. Risk of P loss from the east and west of the catchment is expected to vary due to textural and topographic differences and P history (P fertilizer input and uptake by crops). The CaCl2-extractable P in the catchment was negatively correlated with oxalate extractable Fe (Feox) in soils. This suggests that P may be transported as particulate P (PP) on loam and clay soils due to sorption of P on oxides surfaces, while on sand soil leaching losses may be more likely. On loam and clay soils, higher sodicity and the dispersive nature of subsoils may increase the risk of both dissolved P (DP) and PP loss due to the effects on hydraulic conductivity of the profile.
Hedley's fractionation scheme was used to quantify P fractions in the order of decreasing lability, viz: resin-P > NaOH-Pi > NaOH-Po > acid-P (H2SO4-P) > residual-P. Surface soil had higher resin and NaOH-Pi, which are regarded as water-soluble and readily exchangeable P forms, respectively and expected to contribute to DP in the runoff losses. The residual P was the largest fraction followed by the hydroxide extractable organic-P fraction (NaOH-Po): the former was positively correlated (r) with clay content, organic carbon (OC) and pyrophosphate extractable Fe and Al (0.48**, 0.61**, 0.69** and 0.58**, P < 0.01). A relatively higher value of NaOH-Po in the subsurface layer and positive correlation with OC (r = 0.45**, P < 0.01) suggests potential mobility of P as soluble organic P in run-off, throughflow and leachate.
Phosphorus sorption and its relationship to soil properties was used to assess the potential P release from the catchment soils. Values of P sorption maxima varied from 1111-3333 mg/kg for surface soils and 1010-2917 mg/kg for subsoils. The P sorption isotherms conformed better to the Freundlich equation than the Langmuir equation. A highly significant negative correlation between CaCl2 extractable P and Feox in surface soils (r = -0.65**, P < 0.01) suggests that P was bound to hydrated Fe oxide surfaces and this may determine the concentration and dynamics of loosely bound P equilibrating with leachates and eroded particulate materials. On the other hand, high surface organic matter and the high proportion of total dissolved P in organically bound form may inhibit P sorption on clays and sesquioxides, which would increase P mobility through leaching or runoff losses.
The relationship between soil P concentration and degree of P stratification in the top 0-10 cm of soils along five toposequences was examined to predict the effect on runoff P losses. The total Colwell-P content of the 0-10 cm layer of soils in the catchment was very low in comparison to other studies on P losses from agricultural soils, but soils showed higher P concentration at 0-1 cm depth compared to 5-10 cm (average 37 mg/kg vs. 19 mg/kg). The higher extractable P concentration in the 0-1 cm layer will create a greater P mobilization risk in surface runoff and leachate than analysis of the 0-10 cm layer might suggest. Assessment of P risk using the 0-10 cm data would still be reliable as P concentration in the 0-1 cm layer was linearly related (R2 = 0.59) with concentration in the 0-10 cm layer. The sampling at varied soil depths will result in different critical P levels for estimating the risk of P enrichment in runoff.
In a glasshouse study with intact soil columns, initial high P concentrations in leachate decreased with leaching events suggesting that macropore flow dominated in initial leaching events changing later to matrix flow. The hydraulic behavior of clay and loam soil below 10 cm depends largely on structure and the type of clay minerals and exchangeable Na. Higher levels of exchangeable Na in the subsoil might increase dispersion of clay particles resulting in low permeability leading to ponding of surface water or lateral movement of water at the interface of sand A and clay B horizons. Lateral water movements increase the risk of P losses in the form of DP, dissolved organic P (DOP) or PP. The P concentration in all the P forms (DRP, DOP and TDP) increased significantly with P rates of application (P < 0.01). The DRP concentration was < 2 mg/l in unfertilized columns but an increase to 11 mg/l was observed with P application at 40 kg P/ha. The higher proportion of DOP relative to DRP and its correlation with TDP indicates that the DOP was the major form of P in leachate. However, the estimation of DOP which was by subtraction of DRP from TDP generally overestimates OP concentration.
The TDP load from unfertilized soil was < 0.20 mg/l in runoff and < 2.40 mg/l in throughflow but increased with P application (20, 40 kg P/ha) for both packed box and field studies. Under field conditions, higher P loss was found with broadcast P application compared to drill placement. The higher load of DOP as a proportion of TDP and its significant relationship with TDP in runoff (R2sand = 0.81; R2clay = 0.79) and throughflow (R2sand = 0.94; R2clay = 0.98) in field and box studies also suggests DOP was the major form of P loss from soil. Dissolved OP concentration increased significantly with increase in soluble organic carbon (SOC) in soil solution at 5 cm depth (P < 0.05). Consequently, the amount of organic matter dissolved in soil solution may influence P sorption and mobility. Relatively higher affinity of soil for sorption of DRP compared to DOP might allow DOP to be more mobile through the profile. Higher PP load in clay soil in throughflow indicates subsurface lateral flow along the interface with the horizon of dispersive clay might be an additional risk factor regarding P mobility in clay soils of the catchment.
The runoff, throughflow and leachate were dominated by eroded particles of clay and colloidal organic materials. However, the soil solution collected though 0.1 m pores in the Rhizon samplers had a similar dominance of DOP to the < 0.45 jum filtered samples in runoff and throughflow. This reduces the likelihood that the so-called DOP fraction was mostly P associated with PP in the 0.1 to 0.45 jum size fraction. The composition of DOP in soil solution collected through Rhizon samplers (< 0.1 jum) might provide important insights for P mobility since this more effectively excluded PP than in the < 0.45 jum filtrate used for runoff and throughflow samples. The DOP in soil solution (< 0.1 jum) might be associated with fine colloidal compound such as silicates, metallic hydroxides, humic acids, polysaccharides, fulvic acids and proteins. If so, then most, but not all of the DOP fraction would be organically bound. However, this requires verification.
In conclusion, soil P levels across the catchment were never very high when assessed in the 0-10 cm layer, but levels in the 0-1 cm layer were more than twice as high. Overall, 30 mg/kg (0-10 cm) and hydrological connection to streams. In addition, another 7 % of land had Colwell-P levels > 15 mg/kg, which appears to be a change point in soils for the release of CaCl2 extractable P. These areas, which are predicted to represent critical source areas of the catchment, need careful management. The high proportions of TDP as DOP in runoff, throughflow and soil solution suggest DOP was the major form of P loss from soil. Phosphorus losses from the catchments are also likely in the form of PP in clay and loam soil but leaching losses are more likely in sand. High exchangeable Na in the subsoil of loam and clay soils increases dispersion of clay particles resulting in low permeability of subsoil and greater lateral P mobility as throughflow at the interface of sand and clay textured horizons.
In general, soils of Fitzgerald River catchment had low soil P, but nevertheless significant risk of P loss at Colwell-P > 15 mg/kg. This study provides baseline information for P loss risks in the wheatbelt of WA. Stream water quality monitoring instruments were installed in the upper Fitzgerald River Catchment at 5 stream locations by CSIRO to measure base line concentrations of P. The measured P concentrations were higher than ANZECC trigger values (> 0.05 mg P/l) for management response over the three-year monitoring period (2005-07). Hence this and many other catchments on the south coast and wheatbelt of south west Western Australia need assessment for P loss risks. Previous emphasis in south west Western Australia on P losses from sandy coastal soils under pasture may need to be reconsidered. In the South coast region, cropping land in the medium rainfall zone may still represent a risk of P loss to waterways and risk to water quality. The present study evaluated the risk of P loss based on soil P forms and their mobility. It suggests greater attention needs to be given to the difference between clay and loam soils with dispersive or non-dispersive sub-soils, and to the composition and mobility of DOP. However, a more complete understanding of P loss risks depends on follow-up studies on hydrological flow and connectivity in the upper Fitzgerald River catchment and similar landscapes of south west Western Australia
Instructional technology, L2 writing theory, and IFL: a case-study conducted in a British university among tutors and students
No full textThis study reviews a series of theoretical models and educational experiences, in order to examine how some of the claims made in the existing literature regarding the role of IT - mainly computer technologies - in writing instruction play out in the case of Italian as a Foreign Language (IFL). With this purpose in mind, this study examines a specific context - three IFL modules taught at the University of Warwick - and uses relevant teaching and learning experiences as a case-study and data sample. By using qualitative analysis supported by some quantitative methodologies, this study triangulates data from questionnaires, semi-structured interviews, focus-groups, field notes, classroom observation rubrics, as well as classroom artefacts, including online resources and educational software used over the course of the academic years 2004-2005 and 2005-2006.
The data collected is filtered through a tripartite framework - learning/instructional environment, IFL tutors, and IFL students - designed to address the need expressed in the literature for analysis of multiple dimensions in complex interactions (Abbott, 1997; Athanases and Heath, 1995; Ramanathan and Atkinson, 1999; Snyder, 1997). The salient themes which emerge from the study are the critical roles of IFL tutors' and IFL students' expectations as well as the framework of values underlying these, along with particular features of information technologies themselves, in shaping participants' experiences and practices with respect to IT and writing, sometimes in unanticipated ways.
Finally, the study considers the ways in which the results of the present research support, contradict, or expand existing literature, especially in relation to a number of specific factors, such as: the type of IT used in writing instruction; the physical configurations of IT-enhanced classrooms; and students' as well as tutors' approaches to learning and teaching IFL writing with and without technology. While the present work, like many other studies in the field of SLA and L2 writing, does not provide complete answer to the complex questions of language learning, it highlights
the importance of both the instructional environment as well as the participants' framework
of values. Only then, IT will be able to potentially enhance language instruction and
become an integral component of learning. This research raises new questions, providing
the basis for further research in the area of SLA theory and pedagogy
The Relationship between Cultural Dimensions and Perceptions of Victimization by Teachers
No full textA repository of information for the NICE CROWD project, during the 2023 - 2024 term, led by PIs Kimberly E. Kamper-DeMarco, Jill M. Norvilitis, Jennifer Mitsuyama-Brandenberger, and NICE Chair Brianna Fitapelli
