THE VALUE OF PROTEIN IN FEED BARLEY FOR BEEF, DAIRY, AND SWINE FEEDING

The impact of the protein content of feed barley on the costs of feeding beef, dairy cattle, and swine in Montana is evaluated. A model of least-cost feed rations is constructed to analyze the marginal value of additional protein content in feed barley. The results indicate that increasing the protein content of feed barley above 12% will not substantially increase the value of barley to feeders. This implies that the establishment and maintenance of a protein premium in the feed barley market would tend to result in lower average prices for feed barley because the feed value/protein relationship is concave and the market would be sustaining costs that the inherent value of the commodity could not support.Livestock Production/Industries,

GUIDELINES FOR WESTERN JOURNAL OF AGRICULTURAL ECONOMICS AUTHORS

This article explains the current editorial procedures and policies of the Western Journal of Agricultural Economics. The contents should be of interest both to readers and to authors who plan to submit manuscripts to the Journal. The current editorial policy of the Journal is discussed, the review and publication process is explained, and detailed guidelines for the proper preparation of manuscripts for the Journal are presented.Teaching/Communication/Extension/Profession,

MONEY ILLUSION, GORMAN AND LAU

Any demand equation satisfying Lau’s (1982) Fundamental Theorem of Exact Aggregation and 0° homogeneity in prices and income will have a Gorman (1981) functional form for each income term. This property does not depend on symmetry or adding up. The implications of this result are illustrated by an extensive example.Demand, exact aggregation, functional form, homogeneity

The Public Resource Management Game

Use of public resources for private economic gain is a longstanding, contested political issue. Public resources generate benefits beyond commodity uses, including recreation, environmental and ecological conservation and preservation, and existence and aesthetic values. We analyze this problem using a dynamic resource use game. Low use fees let commodity users capture more of the marginal benefit from private use. This increases the incentive to comply with government regulations. Optimal contracts therefore include public use fees that are lower than private rates. The optimal policy also includes random monitoring to prevent strategic learning and cheating on the use agreements and to avoid wasteful efforts to disguise noncompliant behavior. An optimal policy also includes a penalty for cheating beyond terminating the use contract. This penalty must be large enough that the commodity user who would gain the most from noncompliance experiences a negative expected net return.Renewable resources, public resources policy, optimal contracts

Délimitation des périmètres de protection des puits de pompage en zone agricole à l'aide de la simulation mathématique

Un périmètre de protection de puits de pompage est la surface entourant le puits, dans laquelle des mesures sont prises pour empêcher des contaminants de migrer et de contaminer l'eau de ce puits. Dans l'établissement des périmètres de protection, de nombreux facteurs doivent être considérés, et une approche analytique systématique doit être adoptée. Les modèles mathématiques de simulation peuvent être employés en ce sens et sont souvent les seules méthodes capables de déterminer les périmètres de protection quand des critères quantitatifs sont utilisés. Une telle approche a été appliquée, en couplant un modèle de transport de contaminant en zone non saturée avec un modèle de transport en zone saturée. Le modèle en zone non saturée VULPEST évalue les concentrations de pesticide atteignant la nappe. Ces concentrations sont ensuite utilisées comme données d'entrée du modèle en zone saturée. Ce dernier considère les vitesses d'écoulement et l'influence de chaque puits. Les résultats quantitatifs permettent alors la détermination de périmètres de protection spécifiques à chaque contaminant potentiel. Cette application, réalisée sur un important site de culture de la pomme de terre du Québec, e permis de comparer favorablement les concentrations prédites à celles mesurées dans l'eau d'un puits, et de déterminer le périmètre de protection spécifique au pesticide utilisé. Le cas présenté est un exemple des applications possibles et futures d'une telle méthode pour la détermination des périmètres de protection des puits de pompage.A wellhead protection area is the surface and subsurface area surrounding a waterwell through which contaminants are reasonably likely to move toward and reach. In the past, various approaches have been taken to delineate wellhead protection areas : fixed circles or rings around the well; simplified variable shapes based on geo-hydrologic mapping and classification ; zones with prescribed minimum travel times. However, in establishing wellhead protection areas, many factors need to be considered : zone of influence around the well; well recharge area; flow paths; transport velocities; travel times; sources and types of contamination. To determine a site-specific wellhead protection area, a systematic analytic approach must be taken. Mathematical simulation models may be employed and are often the only method capable to determine the wellhead protection area when quantitative criteria are used.Such an approach can be used in agricultural zones, where pesticides are applied, by coupling a solute transport modal for the unsaturated zone with a saturated zone transport model. The (unsaturated zone) VULPEST model is an evaluation tool for the groundwater contamination by pesticides based on the transport modeling. Developed as a management tool, it permits the evaluation of the groundwater vulnerability to pesticides in terme of risk of contamination. It evaluates the concentrations of pesticide that reach the water table, taking into account the spatial variability of hydrodynamic, physical and physicochemical parameters of the soil. The variability of parameters is taken into account in the Monte Carlo approach. This approach consists of carrying out a sufficient number of simulations so that the distribution of values assigned to each parameter, these values being randomly selected from a chosen probability distribution, approximates the given distribution.The concentrations obtained from the VULPEST model are used as input data in the model which simulates the transport and the fate of the contaminant in the saturated zone. This model uses the finite difference technique to simulate flow and solute transport. It considers the flow velocities and the influence of each well. In steady state conditions, the linked transport models in unsaturated and saturated zones may be considered independent. The quantitative results obtained by these means determine the vulnerability level of the well. Finally, they permit the delineation of the wellhead protection area for a specific contaminant, that is a given pesticide.An application was performed to an important potato crop area in Quebec. Few years ago, this site has shown a contamination of the well water by the pesticide aldicarb. The cultivated soil consists of marine and fluvial sand with medium to coarse grain sizes, deposited on a sea clay with a thickness of about 20 m in some places. Potatoes are intensively grown in this region. In the eighties, a contamination by the pesticide aldicarb was noticed in some wells of this region. The granular form of aldicarb is applied during the sowing period (mid-May) at the recommended rate of 2.24 kg/ha. It has a high solubility (6 000 mg/l) and is leached by soil humidity. The aldicarb is transformed by oxidation to sulfoxide then to sulfone during its transit in the unsaturated zone. After a characterization of the soil physical parameters, calculations were run for both the unsaturated and the saturated zones. The depths of the well and the aquifer are 5 m and 3 m respectively. The thickness of the aquifer affected by pumping is about 2 m. The application of the pesticide aldicarb was done during 1982 and 1983.The predictive results obtained by modelling for the pesticide concentrations in the well water were favorably comparerd to the concentrations measured at the site. The concentrations of pesticide in the water reach their peaks 7 weeks after every application. The maximum concentrations reaching the water table were found to be about 0,5 mg/l. This level exceeds largely the water quality criterion of 9 µg/l set by Health and Welfare Canada, and the one of 10 µg/l of the US-EPA. The well concentrations are calculated by taking into account transport in the saturated zone and decay processes. The maximum concentrations obtained are near 24 µg/l for a decay rate of the pesticide in the aquifer of 0,003 d-1. This decay rate is the one corresponding of the hall-lite of 8 months found by other researchers for Florida soils. The analysis of the water well during this period shows concentrations of about 10 µg/l. Moreover, the leaching of the contaminant into the well, and its persistence in the soil and groundwater is still present over 3 years after the last application. Using the water quality criterion of 9 µg/l set by Health and Welfare Canada, calculations have provided the delineation of the wellhead protection area specific to the pesticide aldicarb. The boundary delineation of water well protection area is determined by the numerical technique of reverse path line. The maximum extension of the well protection area obtained by this mean is 110 meters. It corresponds to a peak arrival with a decay of 1.5 years after the application.The case study shows an example of the possible and future applications for such a method for the delineation of the wellhead protection areas. Such an approach permits to council the best use of pesticides with an appropriate groundwater protection scheme, indeed, agricultural managers can safely decide on the pesticide application rate and date, as on the choice between various pesticides, with regard to the groundwater quality protection. Through this way, regulators and scientists can base their decisions for the registration of new pesticides by testing, before their use, their possible impacts on groundwater. Comparisons can be easily doge between water quality criteria and predicted quantifies, and regulatory decisions can be taken in light of these results

Adsorption du pentachlorophenol sur divers matériaux : Influence de co-adsorbats organiques (Substances humiques et lindane)

Nous avons réalisé, pour de faibles concentrations, l'étude de l'adsoprtion d'un pesticide le pentachlorophénol, sur plusieurs matériaux adsorbants : le charbon actif, la kaolinite et la bentone. Les résultats montrent que l'adsorption du pentachlorophénol sur la kaolinite reste négligeable tandis que la bentone SD-3 (argile traitée) permet d'obtenir des résultats intéressants avec toutefois une capacité maximale d'adsorption 10 à 100 fois plus faible que celle du charbon actif. Le charbon actif reste le meilleur matériau adsorbant pour le pentachlorophénol. La solubilité de ce composé étant très variable en fonction du pH du milieu on constate que l'adsorption du pentachlorophénol-pentachlorophénate (5 mg.l-1) diminue pour des valeurs de pH supérieures au pKa du couple acide-base que nous avons déterminé expérimentalement, égal à 5,9 ± 0,1. L'adsorption du pentachlorophénol n'est pas affectée par la présence d'acides humiques (obtenus à partir de substances commerciales) utilisés comme coadsorbats (10 mg.l-1) alors que les acides fulviques (20 mg.l-1) extraits de sols semblent provoquer une promotion de l'adsorption. On observe d'autre part que le pentachlorophénol n'affecte pas l'adsorption des acides humiques mais augmente légèrement celle des acides fulviques. Ces remarques suggèrent la possible formation d'un complexe acides fulviques-pentachlorophénol. Lorsqu'on utilise le lindane, pesticide hydrophobe comme coadsorbat (165 mg.l-1), on observe encore d'une façon systématique pour tous les nombreux essais une légère promotion de l'adsorption.Adsorption studies for the removal of the pesticide pentachlorophenol found in a number of water supplies (BELAMIE and GIROUD, 1986) were carried out using various materials including kaolinite, bentone SD-3 and powdered activated carbon (WEBER and GOULD, 1966; WEBER and JODELHAH, 1985). It was found that adsorption on kaolinite was negligible, whereas bentone SD-3 presented and adsorption efficiency from 10 to 100-fold less than equivalent quantities of powdered activated carbon (LOTSE et al., 1968; SHAROM et al., 1980). The effect of the pH on the removal of pentachlorophenol by activated carbon was studied. The removal efficiency of pentachlorophenol by activated carbon is better in acidic media. A clear dependence of adsorption on the pH appeared to be the result of a marked variation of the pesticide solubility as a function of the pH (fig. 3). Adsorption of pentachlorophenol/phenate (5mg.l-1) diminishes markedly at pH values above the pKa of this weak acid (that we found equal to 5,9 ± 0,1) when the pentachlorophenol exists almost entirely in ionic form in aqueous solution, and is enhanced at low pH when the percentage of molecular species (whose concentration can be determined from pKa value) becomes significant (WARD and GETZEN, 1970). These remarks and the adsorptive capacities (163 mg.g-1= 0,6 mmol.g-1 at pH = 5,2 and 79 mg.g-1 0,3 mmol.g-1 at pH =12,7), suggest a П-П interaction between pentachlorophenol and activated carbon which seems to be confirmed by the results with bentone SD-3 (tables 1 to 4), and the values of the electrokinetic potential of these materials. This study emphasizes the effect of organic coadsorbates (e.g., dissolved humic substances and the pesticide lindane) on the adsorption capacity of activated carbon for pentachlorophenol. Two different natural organic matters were studied as coadsorbates : purified humic acids from a commercial source (at 10 mg.l-1) and fulvic acids extracted from a top soil horizon (et 20 mg.l-1) (SCHNITZER and SKINNER, 1963; THURMAN and MALCOLM, 1981). Pentachlorophenol adsorption was not affected by humic acids, whereas an increase of adsorption seemed to be observed in the presence of fulvic acids (fig. 6). Pentachlorophenol does not affect the adsorption of humic acids, but improves slightly the removal of fulvic acids. This suggests an association between the two kinds of organic compounds (WERSNAW et al., 1969; KHAN, 1972; OGNER and SCHNITZER, 1970), the resulting « complex », fulvic acids/pentachlorophenol, being more adsorbed than the compounds themselves. The coadsorbate lindane (0,65 mg.l-1) which is easily adsorbed by activated carton (GOMELLA and BELLE, 1975...) seemed also to Improve slightly the removal efficiency of pentachlorophenol by activated carton (fig. 7)

Analyse de sensibilité paramétrique d'un modèle simulant le transport de pesticide dans le sol

Afin de protéger l'eau souterraine des pesticides épandus à la surface des sols agricoles, on doit être capable de prédire et d'évaluer a priori les risques de contamination. La modélisation mathématique, qui est basée sur la représentation des processus, s'avère être un outil à privilégier pour une telle prédiction. Cependant, la fiabilité des résultats de ces modèles est fonction de la précision et de la représentativité des différents paramètres d'entrée. A l'aide d'une analyse de sensibilité, il est possible d'évaluer l'impact de la variabilité de ces paramètres sur les résultats de la modélisation. Une étude de sensibilité menée avec le modèle Pesticide Rosit Zone Model (PRZM) a permis d'identifier les paramètres physiques d'entrée dont la variation apporte le plus de changements au niveau des principaux résultats, c'est-à-dire les paramètres d'entrée auxquels le modèle est le plus sensible. L'utilisation du coefficient de sensibilité relatif s'avère être à cet égard un outil de comparaison fort efficace dans le cadre d'une telle étude. Les paramètres d'apport en eau (précipitations) et en pesticide (taux d'application) sont ceux dont les variations provoquent le plus d'impact au niveau des résultais de la simulation. Egalement, les résultats des simulations sont aussi sensibles aux variations de la capacité au champ et de la densité du sol. La température, le point de flétrissement, ta profondeur d'évaporation et la dispersion sont des paramètres auxquels la modélisation est peu sensible.The ever increasing number of cases of groundwater contamination by pesticides has recently given rise to numerous experimental studies on the tale of these compounds within the soil-water system. In parallel with these experimental studies, the quick and intensive development of numerous simulation models bas emphasized the importance of the various factors and processes controlling the transport of pesticides in the unsaturated zone. The calibration and the validation of such deterministic models, which are especially used in groundwater management, requires the evaluation of several parameters related to the nature of the pesticide as well as to the pedologic and hydrogeological conditions of a given site. The reliability of results predicted by those models is mainly a function of the precision and the representativeness in the evaluation of those parameters at a specific site.The aim of this study was to evaluate the sensitivity of a simulation modes of pesticide movement in the unsaturated zone with regards to the variation in soil physical properties. More particularly, a sensitivity analysis was performed in order to determine the importance of the variation in these parameters with respect to simulation results obtained from the Pesticide Root Zone Model (PRZM). The spatial variability of the composition and structure of the soil, which comes from the site pedogenesis, is the main cause of the variability of the soil water distribution and of the soil transient properties. The sensitivity analysis of a model with respect to the variation in these parameters allows the evaluation of the impact of their representativeness on the model output results. Such an analysis thus allows the determination of an acceptable level of precision (or error) for which an increase of precision in the evaluation of a parameter does not anymore correspond to a significant gain in the representativeness of the model results. It also permits the estimation of the impact of a potential variation of a parameter on the prediction of pesticide transport in the unsaturated zone.The deterministic PRZM modal used in this study has been developed by the US-EPA and devoted to pesticide application on agricultural sites. This modal evaluates the pesticide leaching towards groundwater with respect to the type of culture and pesticide used, the climatic conditions, the soil characteristics and some agricultural practices. Output results from the model can he expressed in concentrations or masses of pesticide, in fluxes or cumulated quantities. Simulations were performed using characteristics and data of the Portneuf region (Quebec). This area of potato farming was until recently one of the Quebec most important sites for aldicarb application before the recommendation of its non use. Cultivated surfaces, which are rather homogeneous, consist of medium-size sand. Simulations were performed river a ten year period (1974 to 1984), implying one application of pesticide a1 the seed-time, and a trop for each year.The parameters of water and pesticide inputs (rain and application rates) are those that induce the higher impact on the simulation results. The simulation results were also influenced by the variation of the field capacity and of the soil bulk density. Temperature, wilting point, maximum evaporation depth and dispersion are the input parameters for which the PRZM model is the less sensitive. The simulation results of pesticide transport, which ultimately consist in predicting the groundwater contamination, are very sensitive to the variations of some physical parameters for which the precision and the representativeness in the measured values are thus very important for the reliability of the results. Considering the spatial variability of a site characteristics, the representativeness of these results is very uncertain if a limited number of data is used in order to determine the mean value. A particular attention has to be focused on the parameters that induce the higher sensitivity of the model. Finally, such a sensitivity analysis shows that a stochastic approach in modelling the solute transport through soil can be a good alternative to take into account the variability of parameters encountered in field situations

Constraints on non-minimally coupled curved space electrodynamics from astrophysical observations

We study interactions of electro-magnetic fields with the curvature tensor of the form $\lambda R_{\mu \nu \alpha \beta}F^{\mu \nu}F^{\alpha \beta}$. Such coupling terms though are invariant under general coordinate transformation and CPT, however violate the Einstein equivalence principle. These couplings do not cause any energy dependent dispersion of photons but they exhibit birefringence. We put constraints on the coupling constant $\lambda$ using results from solar system radar ranging experiments and millisecond-pulsar observations. We find that the most stringent constraint comes from pulsar observations and is given by $\lambda < 10^{11} cm^2$ obtained from the timing of binary pulsar PSR B1534+12.Comment: 9 pages latex, accepted in CQ