Winter Wheat Recropping on Dryland as Affected by Stubble Height and Nitrogen Fertilization

Abstract

AbstractAlthough crop‐fallow systems stabilize production in the semiarid northern Great Plains, fallow often wastes water, minimally controls water and wind erosion, and contributes to the saline‐seep problem. Developing alternate cropping systems which rely less on fallow requires additional crop residue and more specific soil fertility management guidelines. To optimize the potential of a spring wheat‐winter wheat‐fallow rotation for the northern Great Plains, we examined the effects of spring wheat (Triticum aestivum L. ‘Norana’) stubble management (conventional‐till vs. no‐till stubble at heights of 15, 28, and 38 cm) and N fertilization (rate, timing, and source) on winter wheat yields. Grain yields were significantly higher for ammonium nitrate (NH4NO3) than for urea applied at 67 kg N/ha early (1 May) or late (23 May). Maximum grain yields were 2,620 and 2,540 kg/ha for winter wheat seeded directly (no‐tillage) into 15‐ and 28‐cm stubble heights, respectively, with 67 kg/ha of N applied in early May as NH4NO3. With 22 or 45 kg/ha of N applied early (1 May), grain yield increases for NH4NO3 and urea were similar. With a later application at the same rates, NH4NO3 was significantly superior. Nitrogen topdressing of winter wheat in a recropping system must be completed early, either before or soon after spring growth begins and definitely before the end of tillering.