Extension Ag Update
November/December 2003
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Looking for Volunteers for On-Farm N Rate Trials

Emerson Nafziger, Crop Science Dept., University of Illinois, 217-333-4424, ednaf@uiuc.edu

While we have more N rate response data from Illinois trials than any other state has, we need data from more and better-distributed trials in order to better support the new nitrogen recommendations. For this reason, we are asking producers in all parts of the state to carry out N rate trials using field-scale plots and equipment. Our goal for 2006 is to have at least 100 on-farm, N rate trials in Illinois.

We have applied for funding for this work, but will not know until early spring if the funding is available. We would use funding to provide a stipend to each producer to cover the loss of yield due to N deficiency in the low-rate strips, and also to partly compensate the effort. For now, we are asking for volunteers to run such trials, with the understanding that funds may or may not become available. If we are unable to get funding, then those who lay out trials this fall and do not want to continue can delete the trial by applying N next spring.

Doing such a trial is not complicated, if the equipment is available to place rates precisely and to record yield data. Here's a rundown:

  • Strips need to be in a relatively uniform field or part of a field, in a soil type typical for the area. Strips need to be wide enough to match the application equipment, and to allow harvest inside the strip with at least two border rows on each side within the same N rate. This is needed to prevent "spillover" N effects from the next plots. Most strips will be 12 or 16 rows, with 6 or 8 harvested. Strips should be from 1/8 to 1/4 mile long, with a minimum of 400 ft. or whatever length is needed to assure that yields can be taken accurately.
  • We will use five N rates - 0, 50, 100, 150, and 200 lb N per acre. If other forms of N will be applied (DAP, starter, herbicide carrier), these rates can be in addition, but we would not want the lowest rate (the "0") to get more than 40 lb of N. We can live with VRT-applied DAP as long as rates in different parts of the field don't differ by more than 100 lb of DAP (18 lb of N) or so.
  • Any N form and timing that you are using will be acceptable, from ammonia this fall to sidedress next spring. If applying anhydrous next spring, place it so that planted rows are not directly atop the knife tracks. Application before planting will need to be straight with the way the rows will run.
  • Each rate will be applied to three separate strips, with the five rates bunched together onto three "blocks". Here is an arrangement that can be used for the 15 strips, starting and ending with a border on each side of the plot area:
     
    1. 100 lb 6. 200 lb 11. 50 lb
    2. 50 lb 7. 0 lb  12. 150 lb
    3. 200 lb 8. 100 lb  13.  0 lb
    4. 0 lb 9.  50 lb  14.  200 lb
    5. 150 10. 150 lb 15.  100 lb

  • Of the 100 trials in Illinois for 2006, we'd like 75 or 80 of them to be corn following soybean and the other 20 to 25 be corn following corn. For now, we prefer that these trials not be in fields that have had manure applied within the past 10 years.

From our experience with the WATER plots, we estimate that with average-sized strips, the loss of yield from lowered N rates will be less than 100 bushels for the whole trial. Some of this might be compensated by yield gains at the higher N rates (the average N rate is only 100 lb/acre, which means a little less N expense as well). Trials where corn follows corn will often lose more yield than this, and if we get funding the stipend will be larger to cover that difference. Strips typically need to be at least 12 rows wide (maybe 8 rows in rare cases), but making plots only 500 ft. long will mean less yield loss than with longer plots. It is possible to apply rates only half of the way down 1/4-mile rows, then use the normal N rate for the rest of the length, marking the rate change either with GPS or flags.

If you are willing to conduct one of these trials, feel free to lay it out and apply N rates as indicated above. Please contact me if you are doing a trial and I will send a short form that we'll need to put each trial "on the list." Either a yield monitor or a weigh wagon will be acceptable for taking yields next fall.

If you might have interest in doing a trial but would like to talk about it first, please email me at ednaf@uiuc.edu or call 217 333-4424. We will be working with several seed and fertilizer companies on this project, so we may put you in contact with one of them. We probably can't handle a dozen such trials clustered within a county or two, especially if that means not having trials in some areas of the state. So while we might not be able to support all trials with dollars, we will certainly welcome all data. Within reason, the more data we get the better, and every corn producer in Illinois will benefit directly from this effort.