Long-term experiment with ploughed in cereal straw

Abstract

Plooghed in straw in autumn was compared with removal of the straw in two long-term field experiments with barley and oats on clay loam soils. The straw treatments was combined with four levels of nitrogen as calcium nitrate. Effects of straw on grain yields were small. Leaving out straq incorporation and fertilizer N after 24 years in one of the experiments resulted in significant positive after-effects of straw in following years. These residual effects were apparently counteracted by N-assimilation when straw incorporation was continued.