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This article in AJ

  1. Vol. 75 No. 1, p. 94-99
     
    Received: Apr 22, 1982


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doi:10.2134/agronj1983.00021962007500010024x

Effects of Long-Term, Annual Applications of N and P on Corn Grain Yields and Soil Chemical Properties1

  1. M. L. Hooker,
  2. R. E. Gwin,
  3. G. M. Herron and
  4. P. Gallagher2

Abstract

Abstract

Maximum yield production in monocultural cropping systems requires annual applications of fertilizer to maintain adequate soil nutrient levels. The rates of applied N and P fertilizers may vary from conservative to excessive applications. Experiments were established at two locations (Ardic Haplustoll and Aridic Argiustoll) to evaluate the effects of annual applications of N and P, over a period of several years, on corn (Zea mays L.) grain yields and the accumulation of these nutrients in the soil. Maximum grain yields were consistently maintained with N applications of 134 to 180 kg/ha and P applications of 20 kg/ha. Applications of N-rates higher than the optimum resulted in accumulations of residual NO3-N and subsequent leaching. At one location the soil P level was maintained constant for 21 years with the 20-kg P rate. A similar trend was observed for the initial 10 years of the second experiment, however, for the last 4 years soil-P has increased at the rate of 4 ppm annually.

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