Potato Review Group

Contents

Background: influence on crop performance

Application to soil

Potassium concentration in foliage

Further information:

Potassium notes

Potassium model

 

Background: influence on crop performance

  1. Potassium influences transport of nitrogen and sugars in a plant and influences tuber yield by affecting the duration of tuber bulking in particular. Potassium has little influence on the rate of tuber bulking and has no positive affect on the number of progeny tubers.
  2. Potassium may be more important for long than for short duration  crops.
  3. Potassium is important for the water relations of potato tubers and a high concentration of potassium (above that required for yield) can sometimes result in a low concentration of dry matter in tubers, but this is not a consistent response.

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Application to soil

  1. Calculate requirement according to the PRG Potassium Model.
  2. Time of potassium availability is less critical than that of nitrogen or phosphorus and applications can thus be split in time.
  3. A high concentration of potassium fertiliser close to the seed tuber can damage emerging sprouts or developing stolons and result in a reduction in the number of progeny tubers. See Principles of applications to soil.

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Potassium concentration in foliage

  1. The concentration of potassium in the petiole of the 4th leaf provides a good indicator of availability of potassium for growth. Guidance on sampling and identification of the 4th petiole is available here.
  2. Early season measurements can be used to check the success of fertiliser applications.
  3. If potassium is deficient according to the data below, higher applications may be required in future.

Petiole K data

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Further information

Potassium notes

Nutrition 2020 (Includes introduction to / review of potassium)

Applications to seed and soil 2020 (Includes an experiment with foliar applied “Wholly K”)

Potassium application model – background 2019 (A complete revision of the PRG potassium application model)

Nutrient experiments in 2016 – 2017 (Includes experiments on the potential for improving availability of potassium in soil by use of “Blotta” / “DPX”)

Nutrient experiments in 2014&15 2016 (Includes steric K)

Potassium for potatoes 2015 (Availability of potassium in different soils)

Nutrition experiments in 2014 – presented 2015 (Includes steric K)

Potassium application to potatoes 2014 (Influence of cation competition on availability of potassium; relationship between applied and available potassium updated.)

Foliar nutrition 2013 (Includes foliar application of potassium)

Foliar applied potassium 2012 (Potassium physiology; there is a potential for foliar application of potassium)

Foliar nutrition 2012 (Includes foliar application of potassium)

Measurement of potassium in plants 2012 (Research suggests that measurement of potassium as a proportion of leaf fresh weight may be more accurate than dry weigh measurements but commercial tests based on fresh weight are not available)

Potassium for potatoes 2011 (Potassium physiology. N.B. Information on relationship between applied and available K has been superseded.)

Nutrient combinations 2008 (N, P and K combinations: deficiency of one nutrient may limit response to others)

Potassium 2004 (Time of application; duration of tuber bulking. N.B. Information on relationship between applied and available K has been superseded.)

Potassium 1999 (Influence on tuber dry matter concentration; use of petiole tests)

Potassium 1995 (Uptake of potassium)

 

Potassium model

Download the PRG Potassium Model (Excel spreadsheet) here:
PRG Potassium Model