Growth Rate of Mixed Prairie in Response to Nitrogen and Phosphorus Fertilization

Abstract

Earlier initiation of spring growth and increased dry matter production of mixed prairie are important to the livestock industry, particularly in the northern Plains where the winter feeding period is often prolonged. The effect of N and P levels on growth rate and production of mixed prairie was studied over an 8-year period at the Northern Great Plains Research Center near Mandan, North Dakota. Annual application of N had no effect on growth rate prior to May 1; however, during the May 1-May 15 period, and during each successive growth period, rate of growth increased as N level increased up to 160 lb elemental N/acre (160-N). By May 15, plots receiving 40-N produced more dry matter than did plots without N by June 1. As the season progressed, the production lag of the nonfertilized plots became greater. The yield level reached on June 15 by plots receiving 40-N was not attained by the 0-N plots until July 15. Yield levels reached by fertilized plots on July 1 were never attained by nonfertilized plots.