Tillage and weed management effects on forage production in a barley-red clover rotation

Abstract

Tillage and weed management practices used during the establishment year can likely affect forage yield during the subsequent production year(s). This study was conducted as part of a long-term experiment to determine the suitability of conservation tillage practices for red clover (Trifolium pratense L.) production on a Kamouraska clay from 1988 to 1995. Red clover was underseeded with spring barley (Hordeum vulgare L.) in cropping systems including different tillage (MP: fall moldboard plow; CP: fall chisel plow; NT: no-till) and weed management (intensive, moderate, minimum) treatments applied during the establishment year. Red clover dry matter yields and weed biomass were measured twice in the subsequent forage production year. Tillage had no effect on red clover yields in 3 out of 7 yr. Yields were 16% greater with NT in 1 yr and 52% with MP tillage in 3 yr compared with other tillage treatments. Weed response to tillage was consistent over years. Dicot weed biomass increased as tillage intensity was reduced. Monocot biomass was much less with NT than with MP or CP treatments. Red clover yield was 11% greater with intensive weed management, but this yield increase was not associated with differences in dicot or monocot biomass during the forage production year. Red clover yield gain with intensive weed management would need to be weighed against economical and environmental costs to determine the relevance of increased herbicide use in a short-term cereal/forage rotation.