Crop yield response to long-term reduced tillage in a conventional and organic farming system on a sandy loam soil

This paper describes the long-term effects of practicing ten years reduced tillage on crop yields in a conventional and organic farming system context. Data were collected from the BASIS field experiment, which was established in the Netherlands in 2009 to investigate the effects of reduced tillage on crop yield and soil properties in a controlled traffic farming system on a sandy loam soil. The experiment is unique in its focus on root crops grown on ridges, planted crops and small seeded crops, including cash crops such as potato (Solanum tuberosum), carrot (Daucus carota subsp. Sativus), onion (Allium cepa) and sugar beet (Beta vulgaris). The objective of the present paper was to analyse the long-term effects of reduced tillage on the marketable yields of these crops, grown in a conventional (4-year rotation) and organic farming system (6-year rotation). Tillage treatments were conventional deep inversion tillage (CT, mouldboard plough, 23-25 cm depth), reduced tillage with sub-soiling (RTS, chisel plough, 18-20 cm depth), and reduced tillage without sub-soiling (RT). Our key finding is that the two reduced tillage systems, over a 10-year period, provided similar or even higher marketable yields than conventional tillage, for 12 (RTS) and 11 (RT) of the 13 crops grown. Reduced tillage resulted in lower yields in two crops: carrot (-13.4% in RTS and -15.2% in RT) and cabbage (-5.2% in RT). In both cases, yield losses could be partly related to negative effects of crop residues from the preceding cover crop. Our results provide evidence that yield levels of crops grown in RT in our experiment can generally compete with crop yields in ploughed systems. However, crop residue management and seedbed preparation remain a challenge in reduced tillage systems, requiring further attention in research and dissemination.