THE EFFECT OF DIFFERENT PRECEDING CROPS ON THE DEVELOPMENT, GROWTH AND YIELD OF WINTER BARLEY

Reliable estimations of the yield response of winter barley to different preceding crops are necessary for the design of crop rotations. The grain yield and yield components of winter barley (cv. Tapir) following either rapeseed, oats, wheat or barley were determined in five years of field experiments on a sandy loam (Luvisol) at the Hohenschulen experimental station near Kiel, Germany, F.R. The growth, development and incidence of take-all (Gaeumannomyces graminis var. tritici) was measured in a total of three years. On average over the five years barley grown after oats yielded 0.8 t per ha (11 %) more than barley following wheat which was mainly due to a higher number of ears per m2. Barley following either oats or rapeseed produced a higher dry weight and a larger number of tillers per m2 compared with barley grown after wheat or barley. This effect was already present at the sampling date before winter. Take-all ratings were constantly higher in barley following a susceptible crop, but only reached a severe level late in the season and therefore could not explain the observed differences in growth, development and subsequently grain yield. Since no other pathogens affected the development other non-pathogenic causes must be considered as main causes for the described observations and yield differences.