Comparison of organic versus conventional farming: results from long-term lysimeter studies

IntroductionOrganic farming (OF) has established itself as an alternative to conventional farming. Currently, only a few results are available from long-term studies examining the effects of OF on the environment and agriculture.MethodsThe effects of organic soil cultivation were investigated in a 32-year long-term experiment (from 1991 to 2023) using non-weighable gravity lysimeters, taking into account the known limitations of this method, and compared with agriculture based on best management practices (BMP) cultivation principles with regard to nitrogen leaching via seepage and other parameters, such as yield, nitrogen uptake, and nitrogen use efficiency.ResultsCompared with BMP, OF showed an average annual increase of 25 mm in seepage volume over the long term. Nitrogen concentrations in seepage water did not differ significantly between the two farming systems. The annual N load (median) was significantly higher for OF at 26.1 kg ha−1 than for BMP (20.5 kg ha−1). In contrast, the OF lysimeters showed a 35% reduction in long-term dry matter yield.DiscussionThe organic management practiced here must be optimized to avoid long-term increases in N emissions. To achieve this, soil tillage intensity must be reduced, fallow periods during the vegetation-free season avoided, and the plowing of legumes in the fall obviated, as this can be associated with high N mineralization losses. The main challenge in increasing the share of OF in agricultural management systems is to enhance OF productivity by increasing yields and improving yield stability.