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Stark-Billings County |
Extension Spotlites
April 18, 2008
Fertilizer Application When it is Dry, Considerations for this Year
When soil moisture is low, seeding time approaches and fertilizer has not yet been applied, several strategies might be considered. None is without some risk.
First, application of N, P and K fertilizers may be applied prior to seeding using a broadcast application. If the field is in zero-till and there’s rainfall within two to five days, the nitrogen from the urea might volatilize, depending on the temperature and residue cover. Completely dry fields with no morning dew will enable urea to remain intact at the surface for a longer period. If granules are still visible, volatility would be negligible. When the granules disperse due to a light shower or high humidity, conversion of urea to ammonia gas is much more rapid. If the soil is tilled, the urea would be safe from danger of volatility, but the soil will quickly dry, if it has not done so already, to the depth of tillage.
Another strategy is to apply fertilizer at seeding with the seed if the crop can tolerated some fertilizer or ammonia salts. However, most charts are designed with some soil moisture in mind. If the soil is completely dry, then salt injury would be expected at lower fertilizer rates than normal. Rates should be conservative when seed-placed in a drought.
The last strategy is to delay fertilizer application, applying some small amount of phosphate with the seed, if possible, and apply the nitrogen later when the crop has emerged and established some yield potential. This is not a risky strategy for row crops, which are easily fertilized using a side-dress applicator, but it is a riskier strategy for small grains and other solid-seeded crops where knifing in nitrogen later on is not a good option. Top-dressing solid-seeded crops is better conducted using straight-stream nozzle attachments (Chaffer bars) so that leaf burn is reduced and the liquid nitrogen source, usually 28-0-0 (UAN), is more concentrated in a surface band, reducing the rate of urea volatilization.
Regardless of the method, top-dressed nitrogen must have adequate rainfall for the nitrogen to enter the soil and be utilized by the crop.
For more information contact:
Kurt Froelich,
Extension Agent
NDSU Extension Service
Stark-Billings County
1340 W. Villard St.
Dickinson ND 58601-4646
(701) 456-7665