Comparative Performance of Selected Mathematical Programming Models

This study compares the predictive performance of several mathematical programming models. Using the cropping patterns, yields and crop gross margins of eighteen farms over a period of five years we compare the models' optimum solutions with observed crop distributions after the Reform of the EU Common Agricultural Policy of 1992. The results show that the best prediction corresponds to a model that includes expected profit and a qualitative measure of crop riskiness. The results suggest that, in order to obtain reliable predictions, the modelling of farmers' responses to policy changes must consider the risk associated with any given cropping pattern. Finally, we test the ability of the proposed model to reproduce the farmers' observed behaviour with equally good performance under conditions of limited data availability.model performance, mathematical programming, modelling, decision-making, Resource /Energy Economics and Policy,

Cohomology of Toroidal Orbifold Quotients

Let $\phi:\Z/p\to GL_{n}(\Z)$ denote an integral representation of the cyclic group of prime order $p$. This induces a $\Z/p$-action on the torus $X=\R^{n}/\Z^{n}$. The goal of this paper is to explicitly compute the cohomology groups $H^{*}(X/\Z/p;\Z)$ for any such representation. As a consequence we obtain an explicit calculation of the integral cohomology of the classifying space associated to the family of finite subgroups for any crystallographic group $\Gamma =\Z^n\rtimes\Z/p$ with prime holonomy.Comment: Final version. Accepted for publication in the Journal of Algebr

Methods to Evaluate Ruminant Animal Production Responses

In experiment 1, 80 steers (197.0 kg initial body weight; BW for fall, 116.9 kg for spring), were stocked at 2.45 and 4.1 calves/ha in fall and spring, respectively in 16 tall fescue pastures [fall ergovaline (EV) = 1,475 ppb and spring EV = 1,173 ppb] under 2 treatments, mineral (MIN) (n = 8) and cumulative management (CM) (n = 8). Forage allowance did not differ (P = 0.76) between CM and MIN during fall but differed during spring (P ≤ 0.05, 2.55 vs. 3.22 kg DM/kg BW, for MIN and CM, respectively). For fall, average daily gain (ADG) resulted in 0.41 × EV for MIN and 1.05 × EV for CM. For spring, ADG resulted in 0.80 × EV for MIN and 0.94 EV for CM resulting in an increase of ADG for CM as the level of EV increased. In experiment 2, steers (n = 3) were fitted with a device (Icetag; IceRobotics) strapped to left metatarsus that measured motion activity while on varying levels of EV toxicity. Initial lying bouts for CM were 18.4 but decreased by 0.9 bouts for every 1,000 ppb EV increase. Period 2 resulted in standing time for MIN calves of 858.01 min/day (14.3 h/d) whereas CM calves spent 792.01 min/day (13.2 h/d) standing and CM calves took 20% more steps daily than MIN calves. For every 1,000 ppb increase in EV, steps decreased by 275. In experiment 3, calves (n = 4) grazed long sward regrowth (LSR) or short sward regrowth (SSR) tall fescue and alfalfa paddocks for forage quality, visual observations, rumen volatile fatty acids and diet selectivity measurements. No differences in these behavior measurements were observed for either forage (P \u3c 0.05). Within fescue paddocks, ruminal ammonia, total volatile fatty acids (VFA), acetate, and the branch-chain VFA were greater from SSR vs. LSR (P \u3c 0.05), but these differences were not observed (P ≥ 0.11) on alfalfa paddocks. In summary, the effect of combined management strategies offers potential to cope with toxicity in tall fescue pastures. Grazing activities of cattle grazing tall fescue or alfalfa may influence intake, but further research is needed to determine these behavioral modifications when differences in sward height are small

Viability of the Raw Cotton Production in Spain After the Decoupling of the Subsidies

Considering the latest reform of the EU's Cotton Regulation of 29th April 2004, which will come into force in the 2006/07 season, we analyse its impact on the cotton production sector of Andalusia. The decoupling of subsidies implies that producers will be entitled to 65 percent of the amount received in the reference period (three years) irrespective of the crop chosen to grow. The remaining 35 percent (slightly higher) is paid as cotton are a payment. In this research, first from a survey carried out in 2004 we obtained six groups of producers using fact or analysis and cluster analysis. Then, based on this characterization, we assess the impact of two policy scenarios: (a) the implementation of the reform without any additional measures, and (b) the addition of a complementary environmentally based area payment plus the modulation of the decoupled subsidy up to 50 percent according to raw cotton quality. In the first scenario most producers would reduce the use of inputs to a minimum and leave the raw cotton in the fields. In the second scenario the production of cotton would shift from conventional toward Integrated Production with a reduction of 30% with respect to the current hectarage.Cotton, Spain, Mid-Term Reform, Simulation, Multi-Criteria Decision Making, Agricultural and Food Policy, Crop Production/Industries,

Agricultural Risk Aversion Revisited: A Multicriteria Decision-Making Approach

In modelling farm systems it is widely accepted that risk plays a central role. Furthermore, farmers' risk aversion determines their decisions in both the short and the long run. This paper presents a methodology based on multiple criteria mathematical programming to obtain relative and absolute risk aversion coefficients. We rely on multiattribute utility theory (MAUT) to elicit a separable additive multiattribute utility function and then estimate the risk aversion coefficients and apply this methodology to an irrigated area of Northern Spain. The results show a wide variety of attitudes to risk among farmers, who mainly exhibit decreasing absolute risk aversion (DARA) and constant relative risk aversion (CRRA).Risk analysis, Agriculture, Utility theory, Multiple criteria analysis, Risk and Uncertainty,

Demand for Non-Commodity Outputs from Spanish Extensive Agricultural Systems

Agricultural multifunctionality is the recognition of the joint exercise of economic, environmental and social functions by this sector. In order to make this concept operative to support the design of public policies, it is necessary to estimate the social demand for such functions. The main objective of this article is to present two empirical applications in this line. For this purpose we have adopted the agricultural system of mountain olive groves in Andalusia (Southern Spain) at risk of abandonment after the decoupling of the EU subsidies and the agricultural system of cereal steppes in Tierra de Campos (North-western Spain). The economic valuation technique used is the Choice Experiment. The results suggest the existence of a significant demand for the different functions, although the demand is heterogeneous, depending on the socio-economic characteristics of the individuals surveyed.Agricultural multifunctionality, Economic valuation, Choice experiments, extensive agriculture, Andalusia, Castilla-Leon (Spain), Farm Management,

MULTI-CRITERIA ANALYSIS OF FACTORS USE LEVEL: THE CASE OF WATER FOR IRRIGATION

In this paper we present a methodology to analyse input use in the agricultural sector. The novelty of the theoretical model explained is that it has been developed considering a multi-criteria environment. Thus, the optimal input use condition is determined by the assessment of "multi-attribute utility" and "multi-attribute marginal utility". We show how the approach adopted in this paper is a generalization of the single-attribute expected utility theory. The theoretical model developed is further implemented in an empirical application that studies water for irrigation use as a particular case. Results show how multi-attribute utility functions elicited for a sample of 52 irrigators explain differences on irrigation water use in relative homogenous agricultural systems, albeit exhibiting similar water partial utility functions. We conclude that these differences come from the dissimilar weights that farmers attached to each attribute in the aggregate utility function. The irrigated area considered as case study is located in North-western Spain.Resource /Energy Economics and Policy,