Crop yield and energy use in organic and conventional farming: A case study in north-east Italy

The role played by organic farming as an alternative system to conventional farming is widely questioned, since conflicting results on crop yields sometimes greatly affect system efficiency. As a result, prolonged monitoring studies on organic (OF) and conventional farming (CF) systems are still required, especially in real-life farm conditions, in which the entire production process is quantified. In this context, this study reports crop yields (winter wheat, maize, soybean) and energy efficiency, over a 13-year monitoring period, on a farm in north-east Italy in which two sectors are farmed following OF and CF practices. Results showed that organic yields were always lower than conventional ones, averaging 69%, although their range varied greatly over the years (from 45% to 90%) and depended on crop type. Several management constraints had effects on the lower yields, especially reduced available nutrients and cropping season, but also the timings and types of tillage operations. By contrast, OF practices usually had positive effects on the environment, due to reduced energy input mainly fertilisation (−33.4% MJ ha−1 y−1) and the generally higher productivity of invested energy (EOut EIn−1 = 4.53 in OF and 4.28 in CF); energy use differences per product unit were mainly equal. Other factors, such as local climate and soil variability, may have influenced system performance, but as the two experimental sites were located at a distance of 3.5 km from each other, the data reported here are still valuable, in that they represent the results of 13 years of monitoring, during which farm management played a major role. This case study, although conducted in two separate sites, did not highlight the best overall solution at farm level, it does indicate that the agricultural systems applied would be better suited for different situations and targets (e.g., productive, energetic, ecologic).