Optimering av reducerad bearbetning : högre skörd till lägre kostnad

Abstract: Optimization of soil tillage and crop rotation is important in many aspects, but particularly in maximizing profit margins. Since the economic outcome is usually decisive, it can be interesting to study different combinations of soil tillage systems and crop rotations in order to identify the maximum economic outcome. How a crop functions in a particular tillage system determines whether it is profitable to grow that crop. Different tillage systems affect the soil and its processes in different ways. Reduced tillage often works best on weak-structured heavy clays and on silty clays. However, the positive effects arising from reduced tillage can take a few years to develop, so it is necessary to study such systems over longer periods. This study examined how a crop rotation with only cereals (barley and wheat) and a varied crop rotation (cereals, oil seed rape and peas) were affected by different tillage methods in field trials laid out in a randomized split-plot design at three different sites in Central Sweden: Klostergården in Östergötland, Säby in Uppland and Brunnby research station in Västmanland. The following six tillage systems were compared: Ploughing to 23 cm, ploughing to 12 cm, shallow cultivation to 10-12 cm, deep cultivation to 20 cm, cultivation by Väderstad Carrier to 5-7 cm and direct drilling. The parameters measured included draught requirement for tillage, incidence of fungal disease in the crop, soil penetration resistance and crop yield. Finally, an economic analysis was carried out to identify the optimal crop rotation and tillage method combination at each of the experimental sites. The draught measurements showed no clear differences between the crop rotations. However, there were major differences between the tillage methods, as expected. The plant pathological investigations produced varying results but overall, ploughing was generally most effective in controlling crop rotation-borne fungi. Penetration resistance did not differ significantly between the two crop rotations. However, infiltration rate was surprisingly high in the direct-drilled treatment. Yield varied greatly between years, due in part to the human factor. The economic analysis revealed that the most economically favorable option at Klostergården and Brunnby was to employ a monotonous crop rotation, irrespective of tillage method, particularly when the cultivated area was large (>200 ha). The reverse was true at Säby, where a varied crop rotation gave better profitability.