Phosphorus and Potassium
Phosphorus and Potassium
Our current phosphorus (P) and potassium (K) recommendations for native hay may serve as a reference for switchgrass until an improved scheme is developed. Both P and K are immobile nutrients and their recommendation is directly related to supplying power of the soil (suffi ciency). If the soil is near 100 percent sufficiency, additional P or K fertilizer is not needed due to minimal response to applied P or K fertilizer.
| Oklahoma phosphorus and potassium recommendations for native hay based on a soil test. | |||||
|---|---|---|---|---|---|
| P Recommendation | K Recommendation | ||||
| Soil Test P Index | Sufficiency % | P2O5 /A | Soil Test K Index | Sufficiency % | K2O/A |
| 0-10 | 50 | 40 | 0-75 | 40 | 40 |
| 75-125 | 70 | 30 | |||
| 10-20 | 80 | 20 | 125-200 | 85 | 20 |
| 20-40 | 95 | 0 | 200-250 | 95 | 0 |
| >40 | 100 | 0 | >250 | 100 | 0 |
