Identifying causes of non-uniform establishment of red clover underseeded to winter wheat

Red Clover (Trifolium pratense) underseeded to winter wheat provides substantial nitrogen and non-nitrogen benefits to a soil when incorporated into a rotation. However, in recent years, growers have been experiencing difficulties achieving uniform stands of red clover, leading to economic and environmental issues in the following season. The main objectives of this study were to assess factors associated with an underseeded environment that affect red clover growth and establishment and to identify possible management practices to improve end of season red clover biomass production. The study was conducted in Southern Ontario over a two-year period, with six locations each year. The results indicate that end of season red clover dry weight is a function of red clover stand count and red clover dry weight post wheat anthesis and prior to wheat harvest. Red clover stand counts prior to wheat harvest are a function of initial red clover establishment. Red clover stand counts and red clover dry weight pre wheat harvest as well as initial red clover stand counts were defined as functions of soil moisture and light penetration through the wheat canopy. Light penetration through the wheat canopy was influenced by nitrogen application rate on the wheat crop as well as thinning treatments. Treatments did not have an effect on soil moisture. Results indicate that (1) early seeding of red clover is essential to ensure that plants are able to utilize early season light penetration through the wheat canopy and soil moisture and (2) light penetration through the wheat canopy and soil moisture prior to wheat harvest influence red clover biomass and stand counts during this period in the growing season.