Cropping systems with leys : analysis of a long-term experiment in Northern Sweden

Abstract: Climate change affects agriculture all over the world and in the Northern hemisphere the change towards warmer temperatures is more rapid than other parts on the planet. As this progresses the need to produce food in a sustainable way and stabilize or increase yields is essential. In Sweden, as well as the rest of the world, the trend in the 20th centaury has been to produce large quantities of food in an intensified large-scale cropping system where a short crop rotation or monoculture has been the norm. One of the fears in agricultural research during the 1950s was what effect these cropping systems would have on soil properties and yield over time. In order to evaluate these effects, a number of long-term field experiments (LTEs) were established during the 1950-1960s. LTEs gives important information about what is beneficial for the soil and crops over time and in that way, what is beneficial for our food production. For a sustainable food production, it is crucial to know what an agricultural system should include to be resilient and sustainable over time. In this thesis an LTE in northern Sweden, established in the 1950s with 4 different cropping systems and different 6-year crop rotations, was analysed for the effects on barley and ley yield. The results suggest that having an animal-based cropping system with longer ley-years, 5 years, reduces the depletion of soil organic carbon and produce a significantly higher yield trend for barley yield over time compared to cropping systems with 0–2 years of ley in the rotation. The results also suggest that cropping systems with shorter ley-years, 2-3 years, result in significantly higher first year ley yield trends over time, compared to a cropping system with 5 years of ley.