In the autumn 2006 a project was started with the title "Soil structure for Optimal Winter Oilseed Rape". In this essay eight field trials in the southern and middle part of Sweden have been studied between the years of 2006 and 2007. Six of the field trials (R2-4141 and L2-4141) contained different establish methods. The establish methods that were investigated for winter oilseed rape were conventional ploughing, shallow ploughing, shallow cultivation with a Carrier or a cultivator, spread sowing followed by cultivation with a Carrier or a cultivator and sub soiling. The other two field trials (R2-4135 and R2-4135-6) show how winter oilseed rape reacts on different preceding crops (spring barley, winter wheat, fallow and active fallow) and establish methods (conventional ploughing and shallow cultivation). To investigate the soil structure and how it affects the development of the plant, different measurements were made. Some of these were seed bed analysis, water infiltration, soil penetration, plant counting and studying plant development in autumn and spring. The establishment trials were situated in different parts of Sweden, which made an overall comparison difficult. The results of the measurements varied between the trials, but were small within the trials. The differences in yield were small. There were some tendency that a reduced cultivation system resulted in a higher yield on heavy soil and the opposite on light soil. Winter oilseed rape established well in a reduced cultivation system. The crop yield in a reduced cultivation system was in many cases higher than after conventional ploughing. Even the easy and cheap cultivation systems as broadcasted seeding followed by cultivation with a Carrier or a cultivator resulted in good crop yields. The combination of cheap establishment and high yields has in many cases resulted in the best economy. In the experiments with different preceding crops, located outside Uppsala, there were more significant results between the different treatments. In the seedbed analysis there were more small aggregates in the seedbed in a reduced cultivation system. The preceding crop also seemed to have an effect on the aggregate size, with smallest aggregates after winter wheat as a preceding crop, followed by spring barley, fallow and active fallow. The penetration resistance was less after conventional ploughing then after shallow cultivation with a Carrier in the surface soil. The plant development showed that the preceding crop affected the winter oilseed rape more than the cultivation system. In late autumn, the plants were bigger after winter wheat as a preceding crop than after spring barley, although in the spring the difference was not that clear even if the tendency was the same. The yield was more affected by the cultivation system than by the preceding crop. Shallow cultivation with a Carrier raised the yield compared with conventional ploughing. The preceding crop had marginal effect on the yield.
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