4051: Intercropping with cereals for weed management in grain legumes

Hauggaard-Nielsen, Henrik and Nikolajsen, Jakob Tranberg (2005) Intercropping with cereals for weed management in grain legumes. Weed Research.

Summary

Field pea and lupin were either sole cropped or intercropped with barley at two levels of nitrogen application to determine the effects of crop diversification and N-fertility on weed growth and composition, evaluated through six successive harvests during the growing season. Early in the growing season the weed dry matter accumulation was significantly reduced in intercrops compared to the respective pea and lupin sole crops. However, a flush of Trifolium pratense (red clover) completely changed the interspecific competitive interactions between the growing crops. Until 49 days after emergence barley was very competitive towards weeds compared to the grain legumes related to the an efficient soil nitrogen uptake. At later growth stages competition for light and access to atmospheric nitrogen through fixation became more important than competition for a very limited amount of soil mineral N. Obviously, such growth conditions strongly improved grain legume dry matter production and thereby competitive ability towards weeds. In contrast to general findings, final intercrop use of environmental resources for plant growth was only slightly more efficient than the respective sole crops. However, the intercrops ability to dynamically change competitive ability of intercropped species over time was shown to be important to reduce opportunities for weed growth and competitive ability. Diversification of annual crops to resist competitive interactions from the heterogeneous collection of weed phenotypes in a field is discussed.

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