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This article in AJ

  1. Vol. 77 No. 4, p. 616-621
     
    Received: May 3, 1984
    Published: July, 1985


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doi:10.2134/agronj1985.00021962007700040024x

Nitrogen Requirements of Potatoes1

  1. D. T. Westermann and
  2. G. E. Kleinkopf2

Abstract

Abstract

Nitrogen fertilizer applications, for maximum fertilizer efficiencies and crop yields, should be based on the N required by the crop during its various growth stages. The objectives of this paper were to identify the N requirements of the potato plant (Solanum tuberosum L.) during growth and to evaluate selected soil and plant tissue tests as indicators of the plant's N status. Growth analysis data and soil and petiole NO3-N concentrations were obtained at predetermined time intervals from N fertilization treatments in replicated field studies on a coarse-silty mixed, mesic Durixerollic Calciorthrid soil. Maximum early tuber growth occurred when leaf area index was between 2.5 and 3.2 and the tops contained between 79 and 100 kg N ha−1 at the start of linear tuber growth. A preplant N fertilizer application between 67 and 134 kg ha−1 gave these characteristics under the experimental conditions. The maximum dry matter production rate per day (approx. 250 kg ha−1) occurred when there was between 80 and 140 kg N ha−1 in the plant tops and roots. An average tuber growth rate of 0.75 Mg ha−1 day−1 required a N uptake rate of 3.7 kg ha−1 day−1 to prevent the loss of N and dry matter from the tops and roots. Sufficient N was available for this rate when the soil NO3-N concentration was > 7.5 mg kg−1 (0.46-m soil depth), corresponding to 15 000 mg kg−1 NO3-N in the fourth petiole. Soil and petiole NO3-N concentrations may be used to adjust the N fertilization rates during the growing season. This practice has the potential of increasing the overall N fertilizer use efficiency and final tuber yields within the climatic, disease, and variety limitations.

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