Die Bodenkultur - Journal for Land Management, Food and Environment
M. Dachler und A. Köchl:
Effects of long-term crop rotations, preceding crops, N-fertilization and crop residue incorporation on yield and protein content of winter wheat and following spring barley
The effects of 13 different crop rotations with varying proportions of cereals, legumes and root crops were compared under two different climatic regimes. Additionally, the effects of different nitrogen levels, cover crops and crop residue incorporation were determined by the yields of winter wheat (first following year) and spring barley (second following year) as test crops after each complete rotation.
• Nitrogen fertilization had the strongest influence on yield of winter wheat, followed by the effects of preceding crop.
The cumulative effect of the whole crop rotation was, if at all, weakly pronounced.
• The yield of the test crop, winter wheat, showed following ranking in dependence on the preceding crop in the rather dry area: biennial lucerne fallow > annual lucerne fallow > peas >> sugar beets with manure > rape > sunflower = sugar beets without manure = winter rye. The ranking was under more humid conditions: biennial red clover fallow > annual red clover fallow > field bean > oats > sugar beets with and without manure > winter rye.
• The preceding crop also had significant influence on the protein content of winter wheat. The ranking was almost the same as on yield.
• An influence of the preceding crop on yield of the second test crop, spring barley, could not be ascertained, but protein content after red clover or lucerne fallow and sugar beet with additional manure was enhanced.
• The integration of cover crops into pure cereal rotation had positive yield and quality effects on succeding wheat in the semi dry area with persian clover. This was not the case under more humid conditions with spring rape.
• Crop residue incorporation had generally rather negative yield effects. Higher protein contents were observed only in the dry area.
• On the average of all crop rotations tested, highest winter wheat yields were achieved with 120 kg N/ha under dry conditions and with 140 kg N/ha under humid conditions but only in rotations without legumes.
• Differences in the effects of various preceding crops were also observed with medium nitrogen dressings, but these were not as destinctive, as in the N-unfertilized variant. Therefore negative effects of a unfavourable crop rotation only can be compensated by higher nitrogen amounts to a certain extent.
Key words: crop rotation, preceding crop effect, nitrogen fertilization, crop residue incorporation, cover crops.