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Comparison of Broadcast, With-Seed, and Split Fertilizer Applications for Winter Wheat

Compare broadcast versus all fertilizer with seed versus half with seed and half in spring.

Location: Fairfield, WA
Annual precipitation: 20 inches
Rotation: 1991 winter wheat; 1992 winter wheat; 1993 lentils

Standard
- 120 lb 16-20-0-12 with seed plus 160 lb 34-0-0-0 topdress broadcast in fall. (fertilizer/ac = 74-24-0-14)

Total with-seed
- 260 lb/ac 27-8-0-5 with seed (fertilizer/ac = 70-21-0-13)

Split
- 31 lb/ac 11-52-0-0 and 120 lb/ac 30-0-0-6 with seed in fall; 108 lb/ac 30-0-0-8 broadcast on 8 April 94 (fertilizer/ac = 71-16-0-15)

The long term goal is to find an alternative to expensive, high-power-requirement drills that fertilize and seed into dry ground in the fall. The split treatment was originally intended to be half with seed and half banded on the ground, but complications resulted in the change to fall with-seed plus spring topdress. It also ended up with a lower seeding rate--standard and total-with-seed received 90 lb seed/ac, and the split received 65 lb/ac, all Hill 81 winter wheat. Soil samples were taken for soil moisture in the 0-6" surface at planting time. Soil moisture in all plots averaged 2.2 inches/ft total moisture (very dry). Seeding was started 1 Nov 93. Wheat had not yet emerged on 5 Feb 94. Plants per 3 ft of 2 adjacent rows were counted in three areas of each plot on 31 Mar 94 at 2-4 leaf stage. Plants per 3 ft of row averaged 18.5 for standard, 16 for total-with-seed, and 13 for the split treatment, which corresponds proportionately to the lesser seed rate in the split treatment. There were no visual differences between treatments.

Data

Yield, bu/ac of Hill 81 winter wheat

Treatment	Rep 1	Rep 2	Rep 3	Rep 4	Average
Standard	42.2	40.3	45.8	44.6	43.2c
Total	36.4	40.3	42.9	40.3	40.0b
Split	33.6	37.5	38.6	37.0	36.7a
LSD (5%)					2.6
CV					3.7%

Conclusion

There were statistically and agronomically significant differences in yield. It may be that the late emergence of the crop gave an advantage to the most dense plant population, since the yields corresponded to plant counts. Experts recommend against placing large amounts of fertilizer directly with seed as in the total and split treatments. It may have been unusual weather conditions or the particular characteristics of placement with this double disk drill that prevented a large stand reduction.

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Hans Kok, WSU/UI Extension Conservation Tillage Specialist, UI Ag Science 231, PO Box 442339, Moscow, ID 83844 USA Redesigned by Leila Styer, CAHE Computer Resource Unit; Maintained by Debbie Marsh, Dept. of Crop & Soil Sciences, WSU