• Interaction of Fertility Level with Harvest Date and Frequency on Productiveness of Mixed Prairie

      Lorenz, R. J.; Rogler, G. A. (Society for Range Management, 1973-01-01)
      Management practices are needed which will insure sustained production from fertilized mixed prairie. Prior to establishing grazing management practices, a better understanding of N and P fertilizer effects on the vegetation is needed. The interaction of harvest date and frequency with annual applications of N and P was studied over an 8-year period near Mandan, N. Dak. Yield increases were significant when 40 lb. N/acre (40-N) and 80-N were applied, but application of 160-N produced little or no increase over the yield from 80-N. Average yields were 548, 1,298, 1,875 and 1,908 lb./acre for the 0-, 40-, 80- and 160-N levels, respectively. Without N, response to P was small and generally not significant. When N was applied annually, response to P became significant in the fourth and subsequent years. Yields at all fertilizer levels decreased as frequency of harvest increased. Greatest yield reductions occurred when the sequence included harvest in June.