« Previous | Contents | Next »
Listen
Guidelines for farmers in nitrate vulnerable zones
Booklet 3: Nitrogen recommendation tables for cereals, oilseed rape, potatoes and grassland
Contents
Using these tables
Different soil types and assessment of texture
Table 1: Soil types
Table 2: Average rainfall values for the NVZ areas in Scotland
Table 3: Site classes - N residues from previous crops or grass/clover swards
Table 4: N residues from previous crops and grass/clover swards
Winter cereals (notes)
Table 5: Winter wheat, N recommendations (also covers Triticale)
Table 6: Winter barley, N recommendations (also covers winter oats)
Spring cereals (notes)
Table 7: Spring barley (feed or high N malting), N recommendations
Table 8: Spring barley (low N malting), N recommendations (also covers spring oats)
Oilseed rape (notes)
Table 9: Winter oilseed rape, N recommendations
Table 10: Spring oilseed rape, N recommendations
Table 11: Potatoes, N recommendations
Table 12: Swedes and turnips, N recommendations
Table 13: Direct sown grass and grass/clover, N recommendations
N requirements for established grass
Table 14: Grass with low clover, N recommendations
Table 15: Grass with high clover, N recommendations
Seasonal application of nitrogen fertiliser (grassland notes)
Table 16: Seasonal application of annual N rate for grazing
Table 17: Seasonal application of annual N rates for silage and grazing
Using these Tables
These tables are based on information supplied by the Scottish Agricultural College. The recommendations take account of the N released from previous crop residues and grass leys, as well as taking account of the reserves held in different soil types.
In order to assess the fertiliser N required for each crop, the following factors need to be taken into account for each field on your holding:
For cropped fields and establishing new grass
To calculate the N requirement for cropped fields and new grass you should refer to the appropriate crop table in this booklet. The final requirement is calculated by entering all of the information detailed below into
Table A. See the Fertiliser and Manure Planning section for a step-by-step guide.
Soil type. If you do not know the soil types in each field on your holding, page 3 in this booklet tells you how to assess it.
Previous crop, This determines the
N residue group (except where grassland has been ploughed out. In this case the N fertiliser/manure use in the previous 2 years and the grazing management during the months immediately prior to ploughing out determine the residue group). Table 4 in this booklet helps you to determine the N residue group.
Crop to be grown. The crop tables give the
N requirement for each crop, based on the N residue group and soil type. Appropriate adjustment factors are given in the tables, to take account of the following:
1.
intended market and for spring barley, the sowing date.
2.
winter rainfall (1 October to 1 March) was more than 450mm
3.
spring rainfall between first and final spring N dressings was more then 200mm.
For established grassland fields
To calculate the N requirement for established grass fields you should refer to the appropriate crop table in this booklet. The final requirement is calculated by entering all of the information detailed below into
Table B. See the Fertiliser and Manure Planning section for a step-by-step guide.
Soil type. If you do not know the soil types in each field on your holding, Table 1 in this booklet tells you how to assess it.
N fertiliser/manure use in the previous 2 years and grazing during the months immediately prior to the growing season. This determines the
N residue group. Table 4 in this booklet helps you to determine the N residue group.
Rainfall between April and September (Table 2). This information is used, along with the soil type, to determine the Site Class. Table 3 in this booklet tells you how to assess the Site class. The site class and
N residue group then determine the basic grassland N requirement, taking account of the clover content of the sward.
Intended grazing/silage/hay management. This information is used to adjust the basic N requirement.
Further adjustments will have to be made to take account of
N available from any livestock manure that was applied for the planned and/or previous crop. For a step-by-step guide, see the Manure Planning section.
N Residues from different soil types and assessment of texture
Nitrogen residues from soil reserves have been arranged into six soil types (Table 1).
"Shallow" means any mineral soil with less than 40cm depth between the soil surface and the underground rock.
Types of mineral soils can be identified by hand texturing. Take about a dessertspoonful of soil. If dry, wet up gradually kneading thoroughly between finger and thumb until aggregates are broken down. Enough moisture is needed to hold the soil together and for the soil to exhibit its maximum cohesion. There are 2 questions to be answered:
Question 1 | Is it difficult to roll the moist soil into a ball? | Answer | YES, then the soil type is "
Sand";
NO, then ask the second question |
Question 2 | Does the moist soil feel smooth and silky as well as gritty? | Answer | NO, then the soil type is "
Sandy loam";
YES, then the soil type is "
Other mineral soil". |
"
Humose" and "
Peaty soils" are identified by percent organic matter, which can be confirmed by laboratory analysis.
« Previous | Contents | Next »