Table 1.2-12. Nitrogen conversion — approximate pounds of materials required per acre to supply rates of nitrogen recommended per acre.
To compare nitrogen costs for these materials, convert the prices to a per-unit-of-actual-nitrogen basis by dividing the price per ton of fertilizer by the pounds of actual nitrogen in a ton of each material. This figure is given at the bottom of the table. Example:
Compare urea at $800/T with ammonium nitrate at $700/T.
Urea: $800/920 lb N = $0.87/lb N
Ammonium nitrate: $700/670 lb N = $1.04/lb N
In this example, urea is the best buy. Other factors such as suitability of the material, convenience, method of application, and other fertilzer properties also should be considered.
Actual N lb/T = 2,000 × N analysis (as a decimal)
Example: Calculation of lb N/T of 28% liquid nitrogen
Actual N lb/T = 2,000 × 0.28 = 560 lb N/T
| For a nitrogen recommendation of | lb. material per acre to suply rate of N per acre | ||||
|---|---|---|---|---|---|
| Anhydrous ammonia (82% N) | Ammonium nitrate (33.5% N) | Ammonium sulfate (21% N) | Liquid nitrogen (30% N) | Urea (46% N) | |
| 30 | 37 | 90 | 143 | 100 | 65 |
| 40 | 49 | 120 | 190 | 133 | 87 |
| 50 | 61 | 149 | 238 | 167 | 109 |
| 60 | 73 | 179 | 286 | 200 | 130 |
| 70 | 85 | 209 | 333 | 233 | 152 |
| 80 | 98 | 239 | 381 | 267 | 174 |
| 90 | 110 | 269 | 429 | 300 | 196 |
| 100 | 122 | 299 | 476 | 333 | 217 |
| 110 | 134 | 328 | 524 | 367 | 239 |
| 120 | 146 | 358 | 571 | 400 | 261 |
| 130 | 158 | 388 | 619 | 433 | 283 |
| 140 | 171 | 418 | 667 | 467 | 304 |
| 160 | 195 | 478 | 762 | 533 | 348 |
| 180 | 220 | 537 | 857 | 600 | 391 |
| 200 | 244 | 597 | 952 | 667 | 435 |
| 220 | 268 | 657 | 1048 | 733 | 478 |
| Actual N (lbs/T | 1640 | 670 | 420 | 600 | 920 |