STEEP - Broadcast Versus With-Seed Fertilizer for Spring Wheat

Explore the effect of a high rate of pop-up fertilizer with broadcast, incorporated fertilizer.

Standard - 160 lb 34-0-0-0 broadcast and incorporated before seeding (fertilizer/ac=54-0-0-0).
With-seed - 174 lb 34-0-0-0 applied with seed (fertilizer=59-0-0-0).

The spring wheat variety was Penawawa. Planting date was May 23, 1995. Seeding rate ended up at 50 lb/ac rather than the 70 lb/ac intended. The in-furrow treatment ended up with 5 lb/ac more N than the broadcast treatment. Broadcast treatment was with 45 ft. Barber spreader at 54 lb N/ac. With-seed treatment used the 1206 Haybuster drill which delivered 59 lb N/ac. Treated plots were 50 ft. by approximately 350 ft. and two 18.5 ft. strips were harvested from each.

Although plant population was nearly the same, the plants in the standard (broadcast) treatment plots appeared to be more vigorous, emerged earlier, and had larger leaves. These visual differences were most noticeable early in the season and gradually diminished until harvest when they became difficult to detect.

**Spring wehat yields**, bu/ac
Treatment	Rep 1	Rep 2	Rep 3	Rep 4	Average
Broadcast	62.08	54.6	59.13	62.28	59.52
With-seed	53.14	53.75	52.97	55.79	53.91
LSD(5%)					5.42 bu
CV					4.25%

Plant populations on 17 June 95, plants per linear foot

**Plant populations on 17 June 95**, plants per linear foot
Treatment	Rep 1	Rep 2	Rep 3	Rep 4	Average
Broadcast	19	25	28	25	24.25a
With-seed	18	9	24	15	16.50b
LSD(10%)					7.83
CV					23.09%

Conclusion

There was a clear advantage to the broadcast treatment. These results were reversed from a similar 1994 trial with spring barley. 1994 application rates were somewhat higher and topsoil moisture content was similar at seeding. Although soil temperature was not recorded, 1994 temperatures may have been significantly lower since the seeding date was approximately 2 weeks earlier. In 1994, the summer was much drier. Research conducted in 1983-85 by Robert Mahler (UI) on management of starter fertilizer in winter wheat indicates that higher soil temperature and/or lower soil moisture increases risk of stand injury and reduced yield.

Mahler’s tests also revealed significant differences among varieties with respect to the effect of starter fertilizer on both stand and yield. It was generally observed that both stand and yield could be improved with low to moderate rates (up to 35#N/ac), and that yield usually continued to increase somewhat even after rates were raised to levels that resulted in stand reductions of 20% or slightly more. Wide fluctuations in threshold rates for both stand and yield reductions were observed among varieties. Although undocumented, similar differences for spring grains are likely. Whether or not increased seeding rates with more sensitive varieties would compensate is unknown.

The advantages of fertilizer placement in proximity to developing crop root systems, and conversely, possible reduction of between row weed competition may allow a reduction in total fertilizer application with no adverse effect on yield. Time and energy savings with "one pass" fertilizer and seed operations have been well documented. Placing seed and fertilizer together requires less horsepower and less sophisticated equipment.

The need for additional trials with both wheat and barley is indicated.