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The nitrogen fertilizer trial on old crested wheatgrass stands, begun in 1951, was continued for the third season. Spencer Ammonium nitrate (33.5% N) was applied at three different rates to a 12 year old stand of crested wheatgrass on April 21, 1953. Rates of application were the same as in the previous years: light - 150 pounds fertilizer per acre (50 pounds N); medium - 300 pounds fertilizer per acre (100 pounds N); and heavy - 450 pounds fertilizer per acre (150 pounds N). Plots were 7' x 150' replicated four times. The fertilizer was broadcast on the surface from the fertilizer attachment on the grain drill.

The results of the trial are summarized in Table 4. The 1951 and 1952 plots were harvested to determine possible residual effects, and the data from these plots are included in the summary table. Overall yields from these plots this year were quite high compared to the yields obtained in the previous two years.

All rates of application produced appreciable increases in yield over the check this year. The light rate of application produced 4,348 pounds of dry forage per acre, an increase of 57.9 per cent over the check. The medium rate produced 5,508 pounds of forage, 99.5 per cent more than the check. The heavy rate did not produce quite as much forage as the medium rate, averaging 5,354 pounds per acre, which was 93.7 per cent more than the check.

Substantial residual effects were shown from both the 1951 and 1952 applications. In fact the increased production this year from the 1951 and 1952 applications at the medium and heavy rates was greater than the total increase in production for the previous years.

Despite the fact that substantial increases in forage production can be obtained from nitrogen applications in favorable seasons, it remains somewhat doubtful whether such applications are economically profitable. The applications at the medium and heavy rates made in 1951 have in the three season period produced just about a ton more hay than the check plots. With the cost of the ammonium nitrate fertilizer figured at $100 per ton, the cost of the medium application was $15 for fertilizer alone and of the heavy, $22.50. The value of a ton of hay would normally be about $12 to $15. The operation therefore would not quite have paid its way.

The 1952 and 1953 applications are also on the margin of being profitable. The heavy applications for the most part, do not seem to produce much more than the medium (100# N) applications. The choice would therefore be between light and medium rates of application. If the beneficial effects of these applications carry over for several more seasons, the possibilities of economic advantage in the operation will be much improved.

Table 3 - Influence of Nitrogen Fertilizer Treatments on Forage Production from an old Crested Wheatgrass Field. Hay Yields in Pounds per Acre - Oven-dry.
Time of Application Year of Yield Yields form Treatments Percentage Increase in Forage Production Total Additional Forage Production
No N Check 50# N Light 100# N Medium 150# N Heavy Light Medium Heavy Light Medium Heavy
Spring - 1951 1951 1627 1976 2233 2250 21.5 37.2 38.2 349 596 623
  1952 467 456 720 841 -2.5 54.2 80.1 -11 253 374
  1953 3330 3532 4481 4485 6.1 34.6 34.7 202 1151 1155


              540 2000 2152
Spring - 1952 1952 366 619 636 716 69.1 73.8 95.6 253 270 350
  1953 2897 4507 4635 5592 55.8 60.0 93.1 1610 1738 2695


              1863 2008 3045
Spring - 1953 1953 2761 4348 5508 5354 57.9 99.5 93.7 1587 2747 2773

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