Division 1.7.1.3 Test conditions and duration

The test is carried out in the dark at room temperature of 20±2^oC. The moisture content of soil samples should be maintained during the test between 40% and 60% of the maximum water holding capacity of the soil (see section 1.6.4.2) with a range of ±5%. Distilled, deionized water can be added as needed.

The minimum duration of tests is 28 days. If agrochemicals are tested, the rates of nitrate formation in treated and control samples are compared. If these differ by more than 25% on day 28, the test is continued until a difference equal to or less than 25% is obtained, or for a maximum of 100 days, whichever is shorter. For non-agrochemicals, the test is terminated after 28 days. On day 28, the quantities of nitrate in treated and control soil samples are determined and the EC_x values are calculated.