ARCHIVE: Fertiliser Manual (RB209)

Table D.
Soil Nitrogen Supply (SNS) Indices following ploughing out of grass leys

The Indices shown in Table D assume that little or no organic manures have been applied. Where silage fields have received the organic manures produced by livestock that have eaten the silage and the manure has been applied in spring, such fields should be regarded as containing nitrogen residues equivalent to a previous grazing history.

See Step 2 of the Field Assessment Method above for definitions of ‘High N’ and ‘Low N’ grassland.

D1. Light sands or shallow soils over sandstone – all rainfall areas    

 

SNS Index

  Year 1 Year 2 Year 3
All leys with 2 or more cuts annually receiving little or no manure
1-2 year leys, Low N
1-2 year leys, 1 or more cuts
3-5 year leys, Low N, 1 or more cuts

0

0

0

1-2 year leys, High N, grazed
3-5 year leys, Low N, grazed
3-5 year leys, High N, 1 cut then grazed

1

2

1

3-5 year leys, High N, grazed

3

2

1

D2. Medium soils and shallow soils – not over sandstone – all rainfall areas
All leys with 2 or more cuts annually receiving little or no manure
1-2 year leys, Low N
1-2 year leys, 1 or more cuts
3-5 year leys, Low N, 1 or more cuts

1

1

1

1-2 year leys, High N, grazed
3-5 year leys, Low N, grazed
3-5 year leys, High N, 1 cut then grazed

2

2

1

3-5 year leys, High N, grazed

3

3

2

D3. Deep clayey soils and deep silty soils in Low rainfall areas (500-600 mm annual rainfall)
All leys with 2 or more cuts annually receiving little or no manure
1-2 year leys, Low N
1-2 year leys, 1 or more cuts
3-5 year leys, Low N, 1 or more cuts

2

2

2

1-2 year leys, High N, grazed
3-5 year leys, Low N, grazed
3-5 year leys, High N, 1 cut then grazed

3

3

2

3-5 year leys, High N, grazed

5

4

3

D4. Deep clayey soils and deep silty soils in Moderate (600-700 mm annual rainfall) or High (over
700 mm annual rainfall) rainfall areas
All leys with 2 or more cuts annually receiving little or no manure
1-2 year leys, Low N
1-2 year leys, 1 or more cuts
3-5 year leys, Low N, 1 or more cuts

1

1

1

1-2 year leys, High N, grazed
3-5 year leys, Low N, grazed
3-5 year leys, High N, 1 cut then grazed

3

2

1

3-5 year leys, High N, grazed

4

3

2

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