EFFECTS OF SOIL TYPE ON CROP YIELD WEED DENSITY RELATIONSHIPS BETWEEN WINTER-WHEAT AND BROMUS-STERILIS

Bromus sterilis emerged later on the heavy Oxfordshire soil than on the other soils, and at the end of the experiment, the yield of B. sterilis was lowest on this one. Biomass yield of the Triticum aestivum crop was also least on this soil, though there had been no delay in emergence. As a result, this soil gave rise to a distinctive crop yield-weed density relationship in which both crop yield and weed competitiveness were reduced compared with those on the other soils. The different responses of the crop and weed on the clay soil might have been caused by waterlogging. Because of such differences in crop yield-weed density relationships, predictions of crop yield at a given density are likely to be imprecise unless the effects of soil type and climate are included in the model. -from Authors