Scottish Government

9 Nmax STANDARD REFERENCE AND RESIDUE GROUPS

This booklet contains the standard reference information that you will require to complete the Nmax calculation for your farm.

Contents

Page 4, Information required for Grassland Nmax calculation

Table 14 will allow you to determine the appropriate site class for your farm based upon your locality and soil type

Table 15 will allow you to determine the standard nitrogen requirement for each grass field based upon site class and intended grassland management regime

Page 5, Assessing Crop Nitrogen Requirements by Residue Group

A pictorial guide to help you to use the nitrogen residue group tables

Page 6, Previous Crops in Nitrogen Residue Group 1

Crops - cereals, carrots, swedes, turnips (removed) and linseed

Page 7, Previous Crops in Nitrogen Residue Group 2

Crops - harvested fodder (whole crop), oilseed rape, hemp, vining peas and potatoes

Grassland -
1-2 year low N leys, not grazed within 2 months of ploughing out or during September or October

Page 8, Previous Crops in Nitrogen Residue Group 3

Crops - harvested fodder (root only), beans, combining peas and whole crop lupins

Grassland -
1-2 year low N leys, grazed within 2 months of ploughing out or during September or October
1-2 year high N leys, not grazed within 2 months of ploughing out or during September or October
Thin permanent grass, low N, no clover

Page 9, Previous Crops in Nitrogen Residue Group 4

Crop - grain lupin

Grassland -
1-2 year high N leys, grazed within 2 months of ploughing out or during September or October
3-5 year low N leys, not grazed within 2 months of ploughing out or during September or October
Thick permanent grass, low N

Page 10, Previous Crops in Nitrogen Residue Group 5

Crops - leafy brassica vegetables, leafy non-brassica vegetables and grazed fodder

Grassland -
3-5 year high N leys, not grazed within 2 months of ploughing out or during September or October
3-5 year low N leys, grazed within 2 months of ploughing out or during September or October
Permanent grass, high N, not grazed within 2 months of ploughing out or during September or October

Page 11, Previous Crops in Nitrogen Residue Group 6

Grassland -
3-5 year high N leys, grazed within 2 months of ploughing out
Permanent grass, high N, grazed within 2 months of ploughing out

Page 12, Livestock Manure Nitrogen Efficiency

Pages 13, 14 and 15

Appendix 1, Livestock Manures, Typical Standard Values per Manure Type - You should use these standard values unless you use your own analysis

Pages 16 and 17

Manure Sampling Protocol

As the nitrogen content of manure is significantly variable, it is acknowledged that analysis of manures for nitrogen content can be more accurate than the standard values provided. If you have nitrogen analysis results for your manures, you can use these values in place of the standard values to ensure that you are making the best use of all livestock manure nutrients.

Table 14 - Site classes based on average summer rainfall for each NVZ locality

Table 15 - Standard nitrogen requirement for each grass field based upon site class and grass crop usage

Nitrogen Residue Group 1 - Previous Crops in Nitrogen Residue Group 1 are: cereals, carrots, swedes, turnips (removed) and linseed

Adjustments

a. For wheat, an additional 20 kg N/ha is permitted for every tonne that the expected yield exceeds the standard yield.
b. For wheat, an additional 40 kg N/ha is permitted to milling wheat varieties.
c. For barley and oats, an additional 15 kg N/ha is permitted for every tonne that the expected yield exceeds the standard yield.
d. On winter oilseed rape, the spring application can be increased by up to 30 kg N/ha if the expected yield is over 4.0 t/ha.
e. On spring barley, an additional 15 kg N/ha is permitted for high N grain distilling varieties.

Nitrogen Residue Group 2 - Previous Crops in Nitrogen Residue Group 2 are: harvested fodder (whole crop), oilseed rape, hemp, vining peas and potatoes

Grassland Management Regimes in Residue Group 2:
1-2 year low N leys ¹, not grazed within 2 months of ploughing out or during September or October

¹low N means average N use in last 2 years was less than 150 kg/ha/year

Adjustments

a. For wheat, an additional 20 kg N/ha is permitted for every tonne that the expected yield exceeds the standard yield.
b. For wheat, an additional 40 kg N/ha is permitted to milling wheat varieties.
c. For barley and oats, an additional 15 kg N/ha is permitted for every tonne that the expected yield exceeds the standard yield.
d. On winter oilseed rape, the spring application can be increased by up to 30 kg N/ha if the expected yield is over 4.0 t/ha.
e. On spring barley, an additional 15 kg N/ha is permitted for high N grain distilling varieties.
If actual localised rainfall from 1st October - 1st March exceeds 450 mm: add 10 kg N/ha

Nitrogen Residue Group 3 - Previous Crops in Nitrogen Residue Group 3 are: harvested fodder (root only), beans, combining peas and whole crop lupins

Grassland Management Regimes in Residue Group 3:
- 1-2 year low N leys, grazed within 2 months of ploughing out or during September or October
- 1-2 year high N leys ², not grazed within 2 months of ploughing out or during September or October
- Thin permanent grass, low N, no clover

²high N means average N use in last 2 years was more than 150 kg/ha/year, or high clover

Adjustments

a. For wheat, an additional 20 kg N/ha is permitted for every tonne that the expected yield exceeds the standard yield.
b. For wheat, an additional 40 kg N/ha is permitted to milling wheat varieties.
c. For barley and oats, an additional 15 kg N/ha is permitted for every tonne that the expected yield exceeds the standard yield.
d. On winter oilseed rape, the spring application can be increased by up to 30 kg N/ha if the expected yield is over 4.0 t/ha.
e. On spring barley, an additional 15 kg N/ha is permitted for high N grain distilling varieties.
If actual local rainfall from 1st October - 1st March exceeds 450 mm
: add 20 kg N/ha to crops grown in sandy, shallow or sandy loam soils
: add 10 kg N/ha to crops grown in other mineral, humose and peaty soils

Nitrogen Residue Group 4 - Previous Crop in Nitrogen Residue Group 4 is: grain lupin

Grassland Management Regimes in Residue Group 4:
- 1-2 year high N leys, grazed within 2 months of ploughing out or during September or October
- 3-5 year low N leys, not grazed within 2 months of ploughing out or during September or October
- Thick permanent grass, low N

Adjustments

a. For wheat, an additional 20 kg N/ha is permitted for every tonne that the expected yield exceeds the standard yield.
b. For wheat, an additional 40 kg N/ha is permitted to milling wheat varieties.
c. For barley and oats, an additional 15 kg N/ha is permitted for every tonne that the expected yield exceeds the standard yield.
d. On winter oilseed rape, the spring application can be increased by up to 30 kg N/ha if the expected yield is over 4.0 t/ha.
e. On spring barley, an additional 15 kg N/ha is permitted for high N grain distilling varieties.
If actual local rainfall from 1st October - 1st March exceeds 450 mm
: add 20 kg N/ha to crops grown in sandy, shallow or sandy loam soils
: add 10 kg N/ha to crops grown in other mineral, humose and peaty soils

Nitrogen Residue Group 5 - Previous Crops in Nitrogen Residue Group 5 are: leafy brassica vegetables, Leafy non-brassica vegetables and grazed fodder

Grassland Management Regimes in Residue Group 5:
- 3-5 year high N leys, not grazed within 2 months of ploughing out or during September or October
- 3-5 year low N leys, grazed within 2 months of ploughing out or during September or October
- Permanent grass, high N, not grazed within 2 months of ploughing out or during September or October

Adjustments

a. For wheat, an additional 20 kg N/ha is permitted for every tonne that the expected yield exceeds the standard yield.
b. For wheat, an additional 40 kg N/ha is permitted to milling wheat varieties.
c. For barley and oats, an additional 15 kg N/ha is permitted for every tonne that the expected yield exceeds the standard yield.
d. On winter oilseed rape, the spring application can be increased by up to 30 kg N/ha if the expected yield is over 4.0 t/ha.
e. On spring barley, an additional 15 kg N/ha is permitted for high N grain distilling varieties.
If actual local rainfall from 1st October - 1st March exceeds 450 mm : add 20 kg N/ha to crops grown in sandy, shallow or sandy loam soils
: add 10 kg N/ha to crops grown in other mineral, humose and peaty soils

Nitrogen Residue Group 6

Grassland Management Regimes in Residue Group 6:
- 3-5 year high N leys, grazed within 2 months of ploughing out
- Permanent grass, high N, grazed within 2 months of ploughing out

Adjustments

a. For wheat, an additional 20 kg N/ha is permitted for every tonne that the expected yield exceeds the standard yield.
b. For wheat, an additional 40 kg N/ha is permitted to milling wheat varieties.
c. For barley and oats, an additional 15 kg N/ha is permitted for every tonne that the expected yield exceeds the standard yield.
d. On winter oilseed rape, the spring application can be increased by up to 30 kg N/ha if the expected yield is over 4.0 t/ha.
e. On spring barley, an additional 15 kg N/ha is permitted for high N grain distilling varieties.
If actual local rainfall from 1st October - 1st March exceeds 450 mm : add 20 kg N/ha to crops grown in sandy, shallow or sandy loam soils
: add 10 kg N/ha to crops grown in other mineral, humose and peaty soils

Livestock manure nitrogen efficiency

A key aim of the revised Action Programme is to maximise the efficiency of livestock manure use. Applications in the autumn and winter result in a small percentage of the total nitrogen applied being taken up by the crop. For example, an autumn (August to October) application of 6% dry matter cattle slurry, surface applied on a sandy loam soil, will result in as little as 5% of the total nitrogen becoming available to the crop. In comparison, 35% of the total nitrogen would become available if the same application were made in the spring. Incorporating the spring application would increase the amount recovered in the crop to 40% and injecting it would increase this further to 45%. There is therefore a clear environmental and financial benefit in making more efficient use of the nitrogen available from livestock manure applications.

Default minimum efficiency values have therefore been introduced with the intention of minimising the inefficient use of livestock manure. If applications are made in the autumn or winter the default efficiency values take effect. In these situations you may not be able to supply the optimum nitrogen requirement of your crop. This is because the default efficiency value will result in a reduction of the manufactured nitrogen that can be applied.

The situations where this is likely to occur (from now until January 2012) have been highlighted in red in Appendix 1.

The default minimum efficiency values are set out in the table below. Note that increased efficiency values come into force in January 2012.

Appendix 1: Livestock Manures, Typical Standard Values per Manure Type

Farmyard manure ( FYM) - Percentage of nitrogen available to next crop following FYM applications (all crops and all soil types)

Poultry manure - Percentage of nitrogen available to next crop following poultry manure applications
(use the value in brackets for grassland and winter oilseed rape cropping)

Cattle and Dirty Water - Percentage of nitrogen available to next crop following Cattle Slurry and Dirty Water applications
(use the value in brackets for grassland and winter oilseed rape cropping)

Pig Slurry - Percentage of nitrogen available to next crop following Pig Slurry applications
(use the value in brackets for grassland and winter oilseed rape cropping)

Protocol for Sampling Slurry and Solid Manure for Analysis

Why correct sampling matters

The nutrient content of slurry can vary considerably within a store due to settlement and crusting. Similarly, the composition of solid manure in a heap can vary depending on the amount of bedding and losses of nutrients during storage.

It is important that the sample taken represents an 'average' of what is found in the store or heap.

General principles of sampling

It is important, where this is practical and safe, to take a number of samples. If you are unable to take such samples safely you will need to use standard values for manure nutrient content.

Take samples from a range of positions within the store or heap, bulk them together, mix them and then take a representative sub-sample.

The final sample can be sent to the laboratory for total nitrogen analysis. It would be advisable to obtain other analyses at the same time in order to make best use of manures and save you money on fertiliser costs.

Slurries

You must take at least five sub-samples of 2 litres. Pour into a larger container, stir thoroughly and pour a 2 litre sample immediately into a smaller clean container to provide the sample for analysis.

Above-ground stores

Ideally, slurry should be fully agitated and sub-samples taken from the reception pit. If this is not possible, and provided there is safe access from an operator's platform, the five sub-samples can be taken at a range of positions, using a weighted 2 litre container attached to a rope.

Below-ground pits

It may be possible to obtain sub-samples at various positions using a weighted container as above, but never enter the pit, as lethal gases may be present. Do not attempt to take samples during or soon after slurry agitation as large amounts of lethal gases may be released from the stirred slurry.

Earth-banked lagoons

If the slurry has been well agitated, sub-samples can be obtained from the tanker or irrigator as outlined below. Do not attempt to sample direct from the lagoon unless there is an operator's secure platform that provides safe access.

Sampling while spreading

If the tanker is fitted with a suitable valve, it may be possible to take five sub-samples from the stationary slurry tanker at intervals while field spreading is in progress. Or, trays placed in the field can be used to collect samples while the material is being spread.

Solid manures

You must take at least 10 sub-samples of 1 kg each, taken as described below, and place on a clean, dry tray or sheet. Break up any lumps and thoroughly mix the sample. Then take a representative sample of around 2 kg for analysis (you should check the weight required with the laboratory).

Manure heaps

Provided the manure is dry and safe to walk on, identify at least ten locations which appear to be representative of the heap. Having cleared away any weathered material with a spade or fork, dig a hole approx. 0.5m deep and take a 1 kg sample from each point. Alternatively, take sub-samples from the face of the heap at various stages during spreading.

Pig and poultry manure heaps only

For permanently housed pig and poultry enterprises that only produce solid manures, you may wish to provide samples to check compliance with the Livestock Manure N Farm Limit in Nitrate Vulnerable Zones. You must provide 4 samples for analysis in a calendar year (one in each quarter) by following the advice for manure heaps, but the manure heaps must not be more than 12 months old.

Weeping-wall stores

Do not attempt to take samples before the store is emptied as it is not safe to walk on the surface of the stored material. Sub-samples may be taken from the face of the heap once emptying has commenced.

Sampling during spreading

Trays placed in the field can be used to collect samples while the material is being spread. Take care to avoid the possibility of injury from stones and other objects which may be flung out by the spreading mechanism.

Storage and analysis

Slurry samples sent to a laboratory for analysis should be dispatched in clean screw-topped 2 litre plastic containers. Leave at least 5 cm of airspace to allow the sample to be shaken in the laboratory. For solid manures, use 500-gauge polythene bags and expel excess air from the bag before sealing.

Clearly label the samples on the outside of the container or bag and dispatch them immediately or within a maximum of seven days if kept in a refrigerator.

Notes