ETABLISSEMENT DE FONCTIONS DE PRODUCTION N-P-K POUR LE TABAC A CIGARETTE AU QUEBEC

Abstract

Field fertilization tests were carried out with cigarette tobacco to determine production functions. Nitrogen was applied at rates of 0, 12, 27 and 40 kg/ha. Phosphorus was applied at rates of 0, 49, 73 and 122 kg/ha, and potassium at rates of 0, 93, 139 and 232 kg/ha. The nitrogen and potassium had a significant bearing on the yield. The yield response curves showed decreasing ratios. Yield predictions were developed to study the yield surfaces and economic optima. In order to obtain the least costly combinations of N and K, we found the equations of the marginal physical product, the isoquants for various yields and the isoclines. On the basis of the cost combinations and the optimum rates of application of N and K for various situations, we concluded that an economical and balanced fertilizer formula, as is currently recommended, should be used, but that the quantities of K could be increased in relation to the quantities currently recommended.