PROBABILITY OF RESPONSE OF FLAX TO NITROGEN FERTILIZER DEPENDENT UPON PLANTING DATE AND WEATHER

Profitability in agricultural crop production is largely dependent on weather, and specifically on the probabilities associated with weather. Experiments designed to assess the profitability of fertilization account for this by spanning several years and, thus, sampling weather over several years. We measured the response of flax (Linum usitatissimum 'Dufferin') to N fertilization on three planting dates in each of 3 years. Weather patterns and yields differed more among planting dates than among years. The degree of response to N was also dependent on weather, especially during the logarithmic phase of vegetative growth and during the ripening phase. Through several statistical methods, equations were developed that accounted for over 95% of the variability in yield based on meteorological data. These equations were applied in a stochastic simulation of 100 yr of flax trials. The probabilities of response to N and the dollar-return to cost ratios were computed. The sensitivity of these probabilities to the meteorological data was discussed. The estimates suggested that a profitable response of flax to N would occur in about 58% of the years in southern Ontario. Key words: Stochastic, flax, net radiation, degree-day, Linum usitatissimum