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 differe nt preceding crops are necessary for the design of crop rotations. The grain yield and yield components of winter barley (cv. Tapir) followi ng either rapeseed, oats, wheat or barley were determined in five year s of field experiments on a sandy loam (Luvisol) at the Hohenschulen e xperimental station near Kiel, Germany, F.R. The growth, development a nd incidence of take-all (Gaeumannomyces graminis var. tritici) was me asured in a total of three years. On average over the five years barle y grown after oats yielded 0.8 t per ha (11 %) more than barley follow ing wheat which was mainly due to a higher number of ears per m2. Barl ey following either oats or rapeseed produced a higher dry weight and a larger number of tillers per m2 compared with barley grown after whe at or barley. This effect was already present at the sampling date bef ore winter. Take-all ratings were constantly higher in barley followin g a susceptible crop, but only reached a severe level late in the seas on and therefore could not explain the observed differences in growth, development and subsequently grain yield. Since no other pathogens af fected the development other non-pathogenic causes must be considered as main causes for the described observations and yield differences.