• Effects of Nitrogen Source and Phosphorus on Crested Wheatgrass Growth and Water Use

      Power, J. F.; Alessi, J. (Society for Range Management, 1970-05-01)
      The effects of four nitrogen (N) sources upon crested wheatgrass growth were studied for five years at Mandan, North Dakota. The four sources-ammonium nitrate, ammonium sulfate, calcium nitrate, and urea-were applied annually at rates of up to 160 lb N/acre both with and without annual phosphorus (P) fertilization. Dry matter production of crested wheatgrass was increased by N and P fertilization in all years. Only in years of higher production did higher N rate, N source, or any interactions, influence yields. Average yields for the 5-year period were also increased by fertilization with P and with increasing rates of N-but were not influenced by N source. Responses to N fertilization increased by about 380 and 490 pounds for each acre-inch increase in water supply (above 5 inches) with and without P, respectively. In contrast, response to P fertilization was about 50 lb/acre-inch regardless of water supply. Dry matter production and response to N fertilization were both closely correlated with May precipitation (r is greater than or equal to 0.89).