Example 2
Determine the value of the three types of manure for a continuous fescue hay rotation with the following soil test recommendations: For 2 tons per acre of fescue hay: 80 pounds N, 70 pounds P2O5 and 110 pounds K2O (the soil test P1 test was 7, potassium was 108, and organic matter was 2.2).
Assume the slurry application will be surface applied with no incorporation and reduce the availability of ammonia nitrogen by using a factor of 0.6 instead of the 0.95 used for injection. This reduces the available N from 9,465 pounds of N in Example 1 to 8,205 pounds of N.
Base the slurry manure application on N and observe the results. From Example 1, find 7,838 pounds of P2O5 ; and 11,258 pounds of K2O are available. The 8,205 pounds of N at 80 pounds per acre will fertilize 102.6 acres. Applying the 7,838 pounds of P2O5 to 102.6 acres will be a rate of 76.4 pounds per acre, 6.4 pounds per acre above the recommended rate. Applying the 11,258 pounds of K2O to 102.6 acres will be a rate of 109.7 pounds per acre, 0.3 pounds per acre less than the recommended rate.
Basing the application rate on P would result in application to 112 acres at a rate of 70 pounds per acre, an N application rate of 73.3 pounds per acre, and a K2O application rate of 100.5 pounds per acre.
Table for example 2
Value of manure nutrients used by 2 tons per acre fescue hay (based on soil test)
| Herd size (1,000-pound animals) | |||
|---|---|---|---|
| 150 | 300 | 600 | |
| Gross value of excreted manure | $12,542 | $25,084 | $50,168 |
| Value of lagoon N at 80 pounds per acre | $732 | $1,463 | $2,927 |
| Application acres | 30.5 | 61.0 | 122.0 |
| Value of P2O5 used by fescue | $427 | $854 | $1,708 |
| Value of K2O used by fescue | $503 | $1,007 | $2,013 |
| Value of lagoon nutrients used | $1,662 | $3,324 | $6,648 |
| Value of slurry N at 80 pounds per acre | $2,462 | $4,923 | $9,846 |
| Application acres | 102.6 | 205.1 | 410.3 |
| Value of P2O5 used by fescue | $1,436 | $2,872 | $5,744 |
| Value of K2O used by fescue | $1,692 | $3,385 | $6,769 |
| Value of slurry nutrients used | $5,590 | $11,179 | $22,359 |
| Value of solid N at 80 pounds per acre | $1,210 | $2,420 | $4,840 |
| Application acres | 50.4 | 100.8 | 201.7 |
| Value of P2O5 used by fescue | $706 | $1,412 | $2,823 |
| Value of K2O used by fescue | $832 | $1,664 | $3,327 |
| Value of solid nutrients used | $2,747 | $5,495 | $10,990 |