ARCHIVE: Nitrate Vulnerable Zones (NVZs) - Guidance for Farmers. Standard values, manure sampling (Leaflet 3 - PB12736c)

2. Information relating to crop nitrogen requirement

Part 4 of the Regulations establishes a limit on the amount of nitrogen (from manufactured nitrogen fertiliser and crop available nitrogen from livestock manures) that can be applied to specified crops (see Leaflet 7). The N max limits for the specified crops are provided in Table 5 below, together with a range of permitted adjustments to the limits.

Part 6 of the Regulations establishes a closed period for manufactured nitrogen fertiliser, although applications are permitted to some crops which have a crop nitrogen requirement during this closed period (see Leaflet 9). These crops are listed in Table 6 together with their maximum permissible application rates.

Table 5: The N max limits

Crop N max limit
(kg N/ha)
(note a)
Standard crop yield (t/ha)
Wheat, autumn or early winter sown 220 (notes b, c, d) 8.0
Wheat, spring sown 180 (notes c, d) 7.0
Barley, winter 180 (notes b, c) 6.5
Barley, spring 150 (note c) 5.5
Oilseed rape, winter 250 (notes e) 3.5
Sugar beet 120 n/a
Potatoes 270 n/a
Forage maize 150 n/a
Field beans 0 n/a
Peas 0 n/a
Grass 330 (note f) n/a

Notes:

  1. An additional 80 kg N/ha is permitted to all crops grown in fields where the previous or current crop received an application of straw for mulching or paper sludge.
  2. An additional 20 kg N/ha is permitted on fields with a shallow soil type (not shallow soils over sandstone).
  3. An additional 20 kg N/ha is permitted for every tonne that the expected yield exceeds the standard yield.
  4. An additional 40 kg N/ha is permitted to milling wheat varieties.
  5. This consists of a maximum autumn application of 30 kg N/ha (allowed as an exemption to the closed period for manufactured nitrogen fertiliser) and a maximum spring application of 220 kg N/ha. The spring application can be increased by up to 30 kg N/ha for every half tonne that the expected yield exceeds the standard yield.
  6. An additional 40 kg N/ha is permitted to grass that is cut at least 3 times in a year. From 1st January 2012, the N max rate for grass drops to 300 kg N/ha.

Table 6: Crops to which manufactured nitrogen fertiliser may be applied during the closed spreading period

Crop Maximum nitrogen rate (kg/ha)
Oilseed rape, winter (note a) 30
Asparagus 50
Brassica (note b) 100
Bulb onions 40
Over-wintered salad onions 40
Parsley 40
Grass (notes a, c) 80

Notes:

  1. Nitrogen must not be applied to these crops after 31 October.
  2. An additional 50 kg N/ha may be applied every four weeks during the closed spreading period up to the date of harvest.
  3. A maximum of 40 kg N/ha may be applied at any one time.
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