ARCHIVE: Nitrate Vulnerable Zones (NVZs) - Guidance for Farmers. The N max limit (Leaflet 7 - PB12736g)

Annex 1. Step-by-Step Guide for Calculating Compliance with the N Max Limit

N max limits have been established for the following crop types (see Table 5, Leaflet 3):

  • winter wheat, spring wheat, winter barley, spring barley, winter oilseed rape, sugar beet, potatoes, forage maize, field beans, peas and grass.

It is recommended that you take account of the N max limits when planning your use of nitrogen (see Leaflet 6). If you only do the following calculation after harvest you may find that you have applied too much nitrogen and already exceeded the limit.

You will need to carry out the following 6 steps for each of the specified crop types grown on your farm where at least one field has received, or is expected to receive, a higher rate of nitrogen application than the N max limit listed in Table 5, Leaflet 3.

Step 1 Collect your information
Step 2 Calculate the maximum limit for N applications to the crop type taking account of any relevant adjustments (see Leaflet 3)
Step 3 Calculate the crop available nitrogen supplied from all livestock manure applications
Step 4 Calculate the nitrogen supplied from all applications of manufactured nitrogen fertiliser
Step 5 Calculate the total amount of nitrogen applied to the crop type (from manufactured nitrogen fertiliser plus the crop available nitrogen from livestock manure)
Step 6 Compare the total amount of nitrogen applied to the adjusted N max limit for this crop type

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