Nutrient applied
As an example, the total nitrogen applied to a vegetable crop from irrigation water is 14kg/ha/week if 10mm of irrigation water with a nitrogen concentration of 20mg/L is applied every day for a week (that is, 70mm of irrigation water per week). This figure is shown in bold in Table 1.
| Water applied (mm) | 1 | 5 | 10 | 15 | 20 | 25 | 30 |
|---|---|---|---|---|---|---|---|
| 1 | 0.01 | 0.05 | 0.10 | 0.15 | 0.20 | 0.25 | 0.30 |
| 5 | 0.05 | 0.25 | 0.50 | 0.75 | 1.00 | 1.25 | 1.50 |
| 10 | 0.10 | 0.50 | 1.00 | 1.50 | 2.00 | 2.50 | 3.00 |
| 15 | 0.15 | 0.75 | 1.50 | 2.25 | 3.00 | 3.75 | 4.50 |
| 20 | 0.20 | 1.00 | 2.00 | 3.00 | 4.00 | 5.00 | 6.00 |
| 25 | 0.25 | 1.25 | 2.50 | 3.75 | 5.00 | 6.25 | 7.50 |
| 30 | 0.30 | 1.50 | 3.00 | 4.50 | 6.00 | 7.50 | 9.00 |
| 35 | 0.35 | 1.75 | 3.50 | 5.25 | 7.00 | 8.75 | 10.50 |
| 40 | 0.40 | 2.00 | 4.00 | 6.00 | 8.00 | 10.00 | 12.00 |
| 45 | 0.45 | 2.02 | 4.50 | 6.75 | 9.00 | 11.25 | 13.50 |
| 50 | 0.50 | 2.50 | 5.00 | 7.50 | 10.00 | 12.50 | 15.00 |
| 55 | 0.55 | 2.75 | 5.50 | 8.25 | 11.00 | 13.75 | 16.50 |
| 60 | 0.60 | 3.00 | 6.00 | 9.00 | 12.00 | 15.00 | 18.00 |
| 65 | 0.65 | 3.25 | 6.50 | 9.75 | 13.00 | 16.25 | 19.50 |
| 70 | 0.70 | 3.50 | 7.00 | 10.50 | 14.00 | 17.50 | 21.00 |
Note: Milligrams per litre (mg/L) equals parts per million (ppm).
For a 10-week crop, the total amount of nitrogen applied from the irrigation water will be 140kg/ha. The rate of fertiliser nitrogen applied to the crop should be reduced by the amount calculated for the life of the crop (in the example, 140kg N/ha).