Effects of previous legume and oat crops on grain yield and take-all in spring barley

SUMMARY Two experiments compared yields of spring barley following barley, oats, beans ( Vicia faba ), red clover (cut) and (one experiment only) oil-seed rape, and tested effects of trefoil ( Medicago lupulina ) undersown in the preliminary crops of barley and oats. N fertilizer was applied at two rates to preliminary crops, and four rates to the final crop in each experiment. Barley following barley suffered severely from take-all disease ( Gaeumannomyces graminis var. tritici ); barley after other crops was little affected. Other recognized soil-borne diseases were unimportant. Barley yielded less after barley than after other crops except where excessive N fertilizer caused lodging. Clover and beans left N residues equivalent to about 88 and 44 kg fertilizer N/ha respectively; undersown trefoil left inconsistent N residues. Couchgrass ( Agropyron repens ) was more prevalent after barley than after other crops.