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Agronomy Journal Abstract -

Nitrogen and Phosphorus in Jaraguagrass (Hyparrhenia rufa (Nees)Stapf) During the Dry Season in a Tropical Savanna as Affected by Nitrogen Fertilization1


This article in AJ

  1. Vol. 63 No. 1, p. 6-9
    Received: Nov 24, 1969

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  1. L. E. Tergas and
  2. W. G. Blue2



The effect of N fertilization during the latter part of the rainy season on yield and N and P composition of jaraguagrass (Hyparrhenia rufa (Nees) Stapf) during the dry season in the wet-dry Guanacaste Province of Costa Rica was studied. The dry season persists from approximately December 1 through May. A split-plot experiment with N rates as main plots and harvest dates during the dry season as subplots was established on October 13 on a newly mowed grass sward. Forage production increased with N fertilization through January 13 and decreased erratically as the plants dried. Forage N concentrations and contents were increased by N fertilization, but decreased after the initial harvest on November 30 as the dry season progressed. Forage P concentrations and contents also decreased. The decreases in forage N and P concentrations and contents were significantly correlated for each N treatment. Root N concentrations and contents generally increased as forage N decreased with time into the dry season. Forage regrowth during the subsequent rainy season was higher when the dry season harvest was delayed. Apparently these elements were lost from the forage by translocation to the roots. The beneficial effect of N fertilizer on forage quality persisted only for a relatively short time after initiation of the dry season.

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