Nitrogen
Nitrogen
Oklahoma does not have a specific fertilizer recommendation for switchgrass used for biofuel feedstocks, but several field fertility evaluations are under way. The most common recommendation for N is from 0 to 75 lbs per acre. Based on research done in the past, we recommend using the suggestions in Table 4-2 as an interim N recommendation for switchgrass production until a refined set of suggestions is developed based on field tests conducted in Oklahoma. The actual amount of N needed is the number from Table 4-2 minus soil residual N from a soil test report. The needed N should be applied when switchgrass is about 4 to 6 inches tall in the spring.
Nitrogen may increase competition from weeds during establishment. Therefore, no more than 10 lbs of N should be applied, and if the soil test shows more than 10 lbs of N, no N should be applied for switchgrass establishment.
Nitrogen
recommendation for switchgrass production
| Yield Goal (tons/acre) | N (lbs/acre) |
|---|---|
| 1 | 0 |
| 2 | 40 |
| 3 | 80 |
| >4 | 120 |
