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Potatoes: Seed 90-120 days

Potatoes: Seed 90 - 120 days

The nutrient recommendations below are based on SI 113 of 2022 as well as the Teagasc Green Book for Major & Minor nutrient advice. Any nutrient application to crops should be made in line with regulations around N & P use.

Appropriate nutrition is required to sustain high yielding and profitable crops

The importance of Nitrogen, Phosphorus and Potassium is well established for growing crops

Sulphur, Magnesium and Sodium are secondary nutrients which can boost yields in many situations

The appropriate use of micronutrients is essential for maximising crop yield and quality

Having a recent soil analysis at hand is the fundamental first step to building a crop nutrition plan.

Organic manures can be a great source of nutrition for crops. In many cases, they will need to be incorporated into the seedbed

Major Nutrient Requirements (Units/ac)

IndexNitrogen (Units/ac)Phosphorus (Units/ac)Potassium (Units/ac)Sulphur (Units/ac)
1216100244
218492196
316880148
41446896

  1. N rates shown above refer to application rates of available fertilizer. Chemical fertilizer rates should be calculated by deducting the available N contained in organic fertilizer applications from the rates shown in the above table.
  2. See accordian below for information on Soil N Index.
  3. The Phosphorus fertilization rates for soils which have more than 20% organic matter shall not exceed the amounts permitted for Index 3 soils.
  4. P rates shown above refer to recommended application rates of available fertilizer.
  5. Chemical fertilizer rates should be calculated by deducting the P contained in organic fertilizer applications from the rates shown in the above table.
Major Nutrient Requirements (Kg/ha)

IndexNitrogen (kg/ha)Phosphorus (kg/ha)Potassium (kg/ha)Sulphur (kg/ha)
1270125305
2230115245
3210100185
418085120

  1.  

    1. N rates shown above refer to application rates of available fertilizer. Chemical fertilizer rates should be calculated by deducting the available N contained in organic fertilizer applications from the rates shown in the above table.
    2. See accordian below for information on Soil N Index.
    3. The Phosphorus fertilization rates for soils which have more than 20% organic matter shall not exceed the amounts permitted for Index 3 soils.
    4. P rates shown above refer to recommended application rates of available fertilizer.
    5. Chemical fertilizer rates should be calculated by deducting the P contained in organic fertilizer applications from the rates shown in the above table.
Fertiliser Programmes

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  1. Assuming no organic manures are supplied
  2. Assuming Nitrogen Index = 1
Soil Nitrogen Index System

There is, as yet, no satisfactory Irish laboratory test for N in soils at farm level.

  1. Nutrient N advice for grassland systems (grazing and conservation) depends mainly on land use and farming system, and particularly on the stocking rate.
  2. For crops requiring cultivation, the available soil N can be deduced from the previous cropping and manurial history, and the type of soil. Thus, N fertilizer advice is determined by the soil N supply status. This depends in turn on the previous cropping history.

The supply status is categorised into an Index system for grass establishment and tillage crops.

N Index for tillage crops that follow short leys or tillage

Index 1Index 2Index 3Index 4
Previous Crop
Cereals, MaizeSugar beet
Fodder beet
Potatoes
Mangels
Kale
Oil seed rape, Peas,
Beans
Leys (1-4 years)
grazed or cut and
grazed.
Swedes removedSwedes grazed in situ
Vegetables receiving
less than 200 kg/ha nitrogen
Vegetables receiving
more than 200 kg/ha nitrogen

N Index for pasture establishment or tillage crops that follow long leys or permanent pasture

Index 1Index 2Index 3Index 4
Previous Crop
Any crop sown as the 5th tillage crop following long leys or permanent pasture.Any crop sown as the 3rd or 4th tillage crop following long leys or permanent pasture. If original long ley or permanent pasture was cut only use Index 1.Any crop sown as the 1st or 2nd tillage crop following long leys or permanent pasture (see also Index 4). If original long ley or permanent pasture was cut only use Index 2Any crop sown as the 1st or 2nd tillage crop following very good long leys or permanent pasture which was grazed only.

Soil pH
  1. Potatoes can grow very well below pH 6.0 however it is necessary to maintain the soil at a
    pH suitable for the other crops in the rotation.
  2. In a crop rotation with cereals on mineral soils
    target soil pH levels of 6.3 for oats and 6.5 for most cereals will be required.
  3. Lime can take
    years for full reaction with soil, and therefore needs to be applied in good time.
  4. Common scab
    is caused by the organism Streptomyces scabies which is endemic in soils, and infection can be exacerbated by fresh applications of lime.
  5. Lime should not be applied within the
    two years preceding a potato crop because of the increased risk of common scab.
  6. At least 4 years should intervene between liming and sowing a seed potato crop.
  7. Check out the Fertilizer Association of Ireland technical bulletin for more information on Liming
Potassium
  1. Potassium regulates the amount of water in the plant, where there is insufficient potassium, crops will not use water efficiently.
  2. Potassium will also help the crops to withstand stress
    caused by drought, heat, waterlogging, etc.
  3. The use of potassium sulphate is associated with higher dry matter crops.
  4. Lower dry matter when using potassium chloride can result due to
    higher plant water caused by increased chloride supply.
  5. Excessive chloride uptake can also reduce starch content of the tubers.
  6. These potential effects of potassium chloride can be mitigated by using lower application rates or applying 6-8 weeks ahead of planting.
  7. Goulding Soil Nutrition offer Potassium sulphate products as a straight (sulphur of Potash), blend (Potato Plus + GSOP) and Polysulphate. 
  8. Find out more about Polysulphate
Magnesium
  1. Magnesium deficiency is occasionally encountered with potatoes, particularly in sandy soils.
  2. High K applications in conjunction with high soil K can reduce the availability of soil Mg.
  3. Apply 60 kg/ha of Mg for a soil Mg Index of 1 or 35 kg/ha at Index 2.
  4. Goulding Soil Nutrition offer Wolf Trax Magnesium DDP as an option to be coated onto fertilisers, Kieserite, a Mg + S fertiliser and Polysuphate (K, Mg, S, Ca) as options to treat Mg deficiencies. Including Magnesium in your fertilisers allows for earlier intervention (seedbed) when magnesium deficiency is a known issue.
  5. Find out more about Magnesium
Avail
  1. AVAIL is a phosphorous fertiliser enhancer.
  2. It is specifically designed to protect fertiliser P from being fixed into unavailable forms in the soil by antagonistic elements such as iron, aluminium, calcium and magnesium.
  3. Over the last 15 years, many trials have compared the yield increases from using
    phosphate treated with AVAIL against untreated phosphate. Yield increases in potatoes grown using AVAIL are typically in the region of 10-15%
  4. For more information check out our page on AVAIL