EXPECTED CROP YIELD LOSS WHEN CONVERTING TO ORGANIC DAIRY FARMING IN DENMARK

Knowledge of differences between organic and conventional crop yields is of interest for farmers, advisors, politicians, and research scient ists. Based on collected data from Danish organic and conventional mix ed dairy farms the yield difference was estimated to be 21-37% in grai n crops and 12-18% in fodder beets and grass/clover depending on clima tic conditions and soil type. A method is presented to correct for the influence of year and geographic differences using crop and farm-spec ific simulated potential yields as regression variables in a linear st atistical model. An interaction between potential yield and farming sy stem indicates that other growth factors, possibly nutrients, are limi ting the yields on organic farms more than on conventional farms. The results might facilitate modelling and evaluation of economics and ene rgetics of organic farming at the crop and farm level.