by James W. Bauder

It's hard to do and awfully rare. So, just what does it take to grow 100 bushel/acre wheat? First of all, some of the requirements are simply beyond the irrigator's control. Beyond that, a producer must plan well in advance of the season, inputting the proper components with appropriate management practices.

Initial Requirements
Those requirements beyond the irrigator's control include:

  • Three feet of well-drained silt loam soil that is moist at planting time
  • 135 frost free days
  • Timely rain in late May, mid June, and early and mid July
  • Soil conductance of less than 1.0 mmhos/cm
  • No days with temperature over 85oF
  • No days with temperature over 80oF and strong wind

Planning is needed for the following requirements:

  • Little or no weed competition
  • Narrow row spacing and uniform seed spacing within rows
  • At least two previous years out of wheat or barley

Significant inputs include:

  • High quality, weed free seed
  • Sulfur addition of 20% of the nitrogen requirement
  • At least 280 pounds per acre of available nitrogen
  • Phosphorus soil test of at least 18 ppm (Olsen test)
  • Potassium soil test of at least 250 ppm

Management practices include:

  • Nearly perfect uniformity of stand
  • Seeding rate of 90 pounds per acre
  • Early planting and establishment
  • Starter nitrogen and phosphorus fertilizer
  • 90% of the nitrogen applied as anhydrous ammonia
  • Phosphorus banded with the seed

Water
Now, it also takes the right amount of water with proper timing to grow 100 bushel wheat. The basic rule of thumb for wheat grain production is that it takes 5 inches of moisture to insure a crop, with a yield increase of 7 bushels of grain for each additional inch of moisture. For 100 bushel wheat, the water requirement is approximately 20 inches per acre (1 3/4 acre feet), which rainfall, stored soil moisture, and irrigation must supply over the course of the growing season. Three feet of moist silt loam soil will hold about 3-4 inches at 50% depletion, so one must schedule irrigations to this limit

Obviously, you can't irrigate constantly, so here is what you need:

  • Moist soil depth of 3 feet at planting (silt loam)
  • Cool, uniform temperatures through tillering
  • Four inches of moisture after tillering
  • Four inches of moisture at boot stage
  • Four inches of moisture at heading
  • Five inches of moisture at soft dough
  • Count on rainfall for the difference
If your soil is not a gravel-free silt loam, but a sandier or shallower soil, you'll need to irrigate more frequently and apply a little less water each time to get the required 1 3/4 acre feet of water. Now, you have all the information you need to grow that 100 bushel wheat crop. You'll just need a little help from Mother Nature!