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This article in AJ

  1. Vol. 97 No. 6, p. 1493-1501
    Received: Mar 15, 2005

    * Corresponding author(s): beyaertr@agr.gc.ca
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Influence of Nitrogen Fertilization on Multi-Cut Forage Sorghum–Sudangrass Yield and Nitrogen Use

  1. Ronald P. Beyaert *a and
  2. Robert C. Royb
  1. a Southern Crop Protection & Food Research Centre, 1391 Sandford Street, London, ON, Canada, N5T 4T3
    b P.O. Box 186, Delhi, ON, Canada, N4B 2W9


Forage sorghum–sudangrass [Sorghum bicolor (L.) Moench] is a relatively new crop to eastern Canada and the effects of additions of fertilizer N on yield, N accumulation, and N use efficiency are not available for this region. In 1998, 1999, and 2000 the response of forage sorghum–sudangrass to additions of fertilizer N rates (0, 50, 100, 150, 200, and 250 kg N ha−1) either applied as a single sidedress application or split into two sidedress applications was evaluated on a Fox loamy sand (Psammentic Hapludalf). Although timing of N application had little effect on DM production, splitting the N application into two equal applications may be of benefit by enhancing the NUE and ANR of individual cuts. Maximum yield was estimated at 5.95 Mg ha−1 at an N rate of 125 kg N ha−1 and the most economic rates of N ranged from 83 to 107 kg N ha−1 dependent on the cost of N fertilizer and value of hay. Nitrogen concentration increased linearly with increasing N application and the maximum N accumulation was 161 kg N ha−1 at an N rate of 196 kg N ha−1 Total N use efficiency and apparent N recovery decreased with increasing N rates ranging from 36 to 11 kg DM kg−1 and 90 to 24%, respectively. Optimum yield and N efficiency occurred when 100 kg N ha−1 was applied as a split application. Producers in southern Ontario require N fertilizer additions to optimize sorghum–sudangrass yields but need to avoid overfertilization with N to maximize N use efficiency and apparent N recovery.

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