Dryland winter wheat response to tillage and nitrogen within an annual cropping system

Winter wheat (Triticum aestivum L.) can add diversity to dryland crop rotat ions in the northern Great plains, but it is susceptible to winterkill in l ow surface residue environments. A 12-year study was conducted to determine the response of two winter wheat cultivars, Roughrider and Norstar; to til lage system (conventional-till, CT; minimum-till, MT: and no-till, NT) and N fertilizer rate (34, 67, and 101 kg N ha(-1)) in a dryland spring wheat-w inter wheat-sunflower (Helianthus annuus L,) rotation. Grain yields were gr eater with MT (1968 kg ha(-1)) and NT (2022 kg ha(-1)) than with CT (1801 k g ha(-1)), but tillage system effects on grain yield varied among years, In creasing N rate from 34 kg N ha(-1) to 67 kg N ha(-1) increased grain produ ction from 1844 to 1953 kg ha(-1), but yield response to N rate varied amon g years., The greatest overall grain yield (2111 kg ha(-1)) if as obtained with NT and application of 101 kg N ha(-1). Grain yields were lowest during gears when plant-available Hater (PAW) was <300 mm. In years with >400 an PAW, leaf spot disease incidence was greatest, particularly at the lowest N rate with NT. Application of adequate N reduced the disease incidence in a ll tillage treatments. Cultivar differences Here significant 3 out of 12 ye ars, but not consistent. Winterkill was a factor for both cultivars in only 1 year in the CT and MT plots. Winter wheat performed Hell as a rotational crop in this cropping system when using,tfT and NT systems and adequate N fertility, Our long-term results indicate that producers in the northern Gr eat Plains ran use winter wheat successfully in annual cropping systems tha t do not include a fallow period, particularly if NT is used with adequate N fertilization.