تعیین نرخ بهینه مالیات سبز بر انتشار گازهای گلخانه‌ای در گاوداری‌های شیری استان همدان

Introduction: One of the challenges faced by governments in the last century is environmental crisis such as greenhouse gasses. Due to population growth in the world, human activities including agriculture and dairy cattle industry for providing food security for peoples have increased and caused the more pollution and greenhouse gasses emission. to the extent that the amount of greenhouse gasses released by agriculture and dairy cattle's activities in the world is more than greenhouse gasses produced by transportation activities. The main agricultural greenhouse gases (GHG) are methane and nitrous oxide. Methane is produced in the rumen of the cows by methanogen microbes and are naturally present in all ruminant animals. Most methane is emitted when cattle burp. Nitrous Oxide is emitted from soil when urine, faeces and fertilizers broken down by microbes in the soil. Governments and policy makers, by applying policies and programs are struggling to overcome the problems encountered in the environmental field and reduce the negative and harmful effects of human functions on the environment. One of the ways to control and reduce environmental damages such as greenhouse gasses is using economic tools and policies such as taxes on environmental degradation activities.
‌Materials and Methods: This study aimed to evaluate the appropriate green tax rate on methane emissions in dairy cattle industry in Hamedan province. Therefore, of 44 dairy farms in Hamedan province were chosen by simple sampling method and data were collected about the cost of producing this section through questionnaires during 1395-96. By calculating the share of costs using shephard lemma and the Iterative Seemingly Unrelated Regressions method (ISUR), the cost function and cost sharing equations were estimated as a system. The advantage of the current model is that the ISUR estimators utilize the information present in the error correlation of the cross regressions (or equations) and consequently are more efficient than single equation estimation methods such as ordinary least squares. In the selected model the price of animal feed (Pfood(, price of medicine and vaccination )Pmedicin (, price of energy(Pene( and labor wage (Pwag(, are the independent variables.
Results and Discussion: The results indicated that about 52% of the pattern coefficients were significant. Thus using Translog cost function is appropriate for estimating the cost function in dairy cattle units. The calculated R2 criterion for Translog cost function is estimated about 0.99 in this research, which implies that about 99 percent of the variations of milk’s total cost are defined by the variables including animal feed price, labor wage, energy price and the price of medicine and vaccination. Parameters for the input share equations including animal feed price, labor wage, energy price and the price of medicine and vaccination, are calculated respectively as 0.53, 0.36, 0.64, 0.57 and 0.34 for the income share equation. The adjusted coefficient of determination, () for the Translog cost function, is about 0.98, and parameters for the input share equations including animal feed price, labor wage, energy price and the price of medicine and vaccination is respectively 0.47, 0.28, 0.47, 0.36 and 0.22 for the income share equation. Based on the results, the D.W of the equation is 1.98, that indicates the fitted regression is true and there is no autoregressions between residuals and independent variables.
Conclusion: Based on this study results, the appropriate green tax rate for methane emissions in the dairy cattle industry is 1.1% per kilogram of milk production. The results revealed a negative relationship among green tax rate and pollution emissions coefficient and marginal cost of production. Also, a positive relationship between green tax rate and the output price has been detected. This signifies that by increasing green tax rate, the emission of pollutions by dairy cattles is reduced. So putting emphasize on the application of green taxes in order to reduce emissions of methane greenhouse gas. It is also recommended that relevant organizations such as the country's environmental organization, by examining the prevalent infrastructure in the country and providing conditions, use green taxes as an economic tool for controlling and reducing environmental pollution. Moreover, in the feasibility studies and the pre-construction of the generating unit, the green tax should be considered in the evaluations.