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This article in AJ

  1. Vol. 91 No. 4, p. 637-642
     
    Received: Sept 1, 1998


    * Corresponding author(s): adhalvor@lamar.colostate.edu
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doi:10.2134/agronj1999.914637x

Sunflower Response to Tillage and Nitrogen Fertilization under Intensive Cropping in a Wheat Rotation

  1. Ardell D. Halvorson *a,
  2. Alfred L. Blackb,
  3. Joseph M. Krupinskyb,
  4. Stephen D. Merrillb and
  5. Donald L. Tanakab
  1. a USDA-ARS, Soil–Plant–Nutrient Res., P.O. Box E, Fort Collins, CO 80522 USA
    b USDA-ARS, Northern Great Plains Res. Lab., P.O. Box 459, Mandan, ND 58554 USA

Abstract

Sunflower (Helianthus annuus L.) is a warm-season, intermediate water-use crop that can add diversity to dryland crop rotations. Reduced tillage systems may enhance sunflower yield in intensive cropping systems. A 12-year study was conducted to determine how sunflower cultivars of early and medium maturity respond to tillage system (conventional-till, CT; minimum-till, MT; no-till, NT) and N fertilization (34, 67, and 101 kg N ha−1) within a dryland spring wheat (Triticum aestivum L.)–winter wheat–sunflower rotation. Averaged across N rates, cultivars, and years, sunflower seed yields were greater with MT (1550 kg ha−1) than with NT (1460 kg ha−1) and CT (1450 kg ha−1). Increasing N rate above 34 kg N ha−1 generally increased grain yield, but varied from year to year. The tillage × N interaction showed that the highest seed yields were obtained with NT (1638 kg ha−1) and MT (1614 kg ha−1) at 101 kg N ha−1 Total plant-available water (TPAW) of <350 mm greatly reduced sunflower yield potential, due to water stress, compared with yields for 350 to 500 mm of TPAW. TPAW > 500 mm did not result in increased sunflower yields over those with 350 to 500 mm TPAW. Yield differences between cultivar maturity classes varied from year to year and with tillage and N level. At the lowest N rate, weeds were more problematic in NT than in CT and MT plots. More N fertilizer may be needed with NT to optimize sunflower yields than with CT and MT, because of less residual soil NO3–N with NT. Results indicate that producers in the northern Great Plains can use sunflower successfully in annual cropping systems, particularly if MT and NT are used with adequate N fertilization.

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Copyright © 1999. American Society of AgronomySoil Science Society of America