Nitrogen Timing for Winter Pasture - Does it Matter?
Alot of thought goes into planning winter pasture production. Such thoughts may include: How many acres do I need? What varieties should I plant? Will the armyworms eat more grass than the cattle? How much nitrogen should I use?
Sometimes, lost in these thoughts is the time to apply nitrogen fertilizer for the best results in your operation.
Your timing of nitrogen application will obviously be different if you run only spring stockers versus in both the fall and the spring. How much difference does it make? To answer that, I'd like to share some data from our Red River Research Farm at Burneyville, Okla.
This research was conducted from 1979 to 1992, so it covers a wide range of weather patterns. A mixture of rye, wheat and ryegrass was fertilized with different rates of nitrogen at different times. Nitrogen rates were 0, 50, 100, 150 and 200 lbs. of actual nitrogen per acre. Application timings were:
- all applied in the fall,
- all applied in the spring, and
- 1/2 applied in the fall and 1/2 applied in the spring.
The results were rather interesting. The optimum nitrogen rate for the period was 150 lbs. of actual nitrogen per acre. The interesting results centered on the timing of the nitrogen.
First, as seen in Figure 1, at the end of the growing season there was no difference in total forage yield regardless of when the nitrogen was applied. The total amount of forage produced (November through June) was the same if the nitrogen was all applied in the spring, all applied in the fall or split between the fall and spring.
However, there was a difference in when the forage was produced. Figure 2 shows how fall forage yields (November through February) are affected by timing of nitrogen application. More forage was made in the fall when all the nitrogen was applied in the fall than when the application was split. If you are aiming for fall forage, consider applying most or all of your nitrogen for the growing season up front.
Figure 3 shows that applying all the nitrogen in February makes more spring forage than applying all the nitrogen in the fall or splitting the application. If you are primarily interested in spring stockers, the best plan would be to apply little or no nitrogen in the fall and apply most or all of it in the spring.
The best time to apply nitrogen fertilizer to winter pasture depends on the goals for your operation. For producers from outside our area, remember that our research was conducted on a site with minimal chances for leaching or denitrification. It may not be advisable to apply all the nitrogen for winter pasture in the fall in areas of high rainfall or in environmentally sensitive areas.