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Nitrogen Application Increases Yield and Early Dry Matter Accumulation in Late-Planted Soybean


This article in CS

  1. Vol. 45 No. 3, p. 854-858
    Received: July 29, 2003

    * Corresponding author(s): weavedb@auburn.edu
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  1. R. Scott Taylor,
  2. David B. Weaver *,
  3. C. Wesley Wood and
  4. Edzard van Santen
  1. Dep. of Agronomy & Soils, Auburn Univ., Auburn University, AL 36849


In double-cropped soybean [Glycine max (L.) Merr.] planting is delayed, with a corresponding decrease in yield associated with photoperiod-induced early flowering and reduced accumulation of dry matter during the vegetative growth period. Application of nitrogen (N) has been shown to improve yield of late-planted soybean. We conducted a field study to determine the optimum economic rate of N that would stimulate early dry matter accumulation, and thus yield, in late-planted soybean. The effects of three planting dates (mid-June, late-June, and mid-July), two MG VIII cultivars (Kuell and Prichard), and five N rates (0, 25, 50, 75, and 100 kg ha−1) were studied for 2 yr at three Alabama locations (Fairhope, Shorter, and Crossville). Nitrogen application of 60 to 70 kg ha−1 maximized yield and R1 dry matter accumulation. However, N reduced nodule number and mass, but had no effect on R1 plant height, mature plant height, or seed quality, protein and oil content. Yield was reduced linearly by later planting, but there was no interaction between N rate and planting date for yield. Kuell was taller at maturity and had more R1 dry matter than Prichard, but Kuell yielded more than Prichard in only one environment and there was no cultivar × N rate interaction for yield. At current prices for N and soybean, we concluded that N can be a viable input for double-cropped soybean at an optimal economic rate of 59 kg ha−1

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