AHDB Potatoes Fertiliser Calculator

Introduction

Farm details

Details marked with a * must be entered

Farm name
Address

Town
Postcode	*

Country

Field details

Field name

Annual rainfall (mm) *

Soil type

Rainfall category The rainfall category is used to assess the Soil Nitrogen Supply (SNS) index. You can change the rainfall category if you have more accurate information on either your annual rainfall or excess winter rainfall.

The rainfall category is used to assess the Soil Nitrogen Supply (SNS) index. You can change the rainfall category if you have more accurate information on either your annual rainfall or excess winter rainfall.

LowMediumHigh

Soil Analysis

Date sampled If you enter soil analysis, you must also enter a date for soil analysis. If you do not enter a date, the calculator will not use any soil analysis entered, and will base recommendations on a default soil index of 2 (England/Wales) or moderate (Scotland). If your soil was sampled on more than 1 date, enter the earlier date here.

If you enter soil analysis, you must also enter a date for soil analysis. If you do not enter a date, the calculator will not use any soil analysis entered, and will base recommendations on a default soil index of 2 (England/Wales) or moderate (Scotland). If your soil was sampled on more than 1 date, enter the earlier date here.

P (mg/l)

P Index

K (mg/l)

K Index

Mg (mg/l)

Mg Index

SNS (kg/ha)

Only enter the Soil Nitrogen Supply (SNS) if you have results from soil mineral nitrogen (SMN) analysis this year. Sampling to 90 cm is recommended when sampling from January onwards. Sampling to 60 cm is satisfactory when sampling in the autumn. If there is no entry here, the SNS index (England/Wales) or N residue group (Scotland) will be automatically based on previous cropping, soil type and rainfall (England and Wales only).

Previous crop

Arable

Grass

Grass history Select the grass history of the field. This is used to identify the SNS index/status.

*

Crop group

*

Crop type

*

Crop info note

*

Current potato crop

Variety name

Or

Variety group Nitrogen recommendations split potato varieties into one of four groups according to their degree of determinacy (a measure of the crop’s capacity to maintain leaf production after the first appearance of flowers).

Nitrogen recommendations split potato varieties into one of four groups according to their degree of determinacy (a measure of the crop’s capacity to maintain leaf production after the first appearance of flowers).

*

Growing season Growing season is the length of time between anticipated 50% plant emergence and haulm death. You can use the calendar feature next to the drop-down menu to help you calculate your growing season length.

Growing season is the length of time between anticipated 50% plant emergence and haulm death. You can use the calendar feature next to the drop-down menu to help you calculate your growing season length.

*

Select estimated date for 50% plant emergence

Select estimated date of haulm death

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September 2021

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Expected yield This is the expected total biological yield (not graded/marketable yield), which will be used to adjust the potash fertiliser recommendations (England/Wales only). If you leave this blank, recommendations will be based on a yield of 50 t/ha.

This is the expected total biological yield (not graded/marketable yield), which will be used to adjust the potash fertiliser recommendations (England/Wales only). If you leave this blank, recommendations will be based on a yield of 50 t/ha.

Manure application

Manure type

Application date

Application rate Enter the rate of manure application. The default application rate shown is a typical average rate which should be changed if more specific information is available.

Enter the rate of manure application. The default application rate shown is a typical average rate which should be changed if more specific information is available.

Application method

Method of soil incorporation

Delay to soil incorporation This is the time between manure application
and incorporation into the soil.

Manure analysis

Dry Matter (%)
Total N (kg/t or kg/m³)
Ammonium-N (kg/t or kg/m³)
Uric acid-N (kg/t or kg/m³) $Uric-acid N is an important part of the readily available N fraction of poultry manures only.$
Nitrate-N (kg/t or kg/m³)
Total P₂O₅ (kg/t or kg/m³)
Total K₂O (kg/t or kg/m³)

Typical nutrient figures are shown for the selected manure type. You may edit these figures if you have more specific information.

Fertiliser recommendations

Value of manure nutrients

Manure nutrient value

Adjust nutrient prices

Ammonium nitrate (34.5% N)	£/tonne	Nitrogen (N)	pence/kg
Triple superphosphate (46% P₂O₅)	£/tonne	Phosphate (P₂O₅)	pence/kg
Muriate of potash (60% K₂O)	£/tonne	Potash (K₂O)	pence/kg

Fertiliser buying requirement

Calculate your fertiliser buying requirement

This table can be used to calculate your fertiliser buying requirement. Enter the crop area. You can add new fertiliser products and edit the product application rate. For further information see User Guide available from the Introduction tab.
Fertiliser requirement			N	P₂O₅	K₂O	MgO

Area (ha)
Fertiliser product					Application rate	Total requirement	Fertiliser nutrients applied (kg/ha)
Name	% N	% P₂O₅	% K₂O	% MgO	kg/ha of product	tonnes of product	N	P₂O₅	K₂O	MgO
AN
TSP
MOP
Epsom salts




					Total nutrients applied (kg/ha)
					Fertiliser requirement (kg/ha)

Report

Fertiliser calculator report

Additional information

Record here any additional information for inclusion in the report, e.g. changes to the recommended fertiliser rates.

Fertiliser advice