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Table
1. Potassium efffects on yield and process quality. |
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K Rate
lb/acre
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Effect on
US #1 Yield
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Effect on % Dry Matter
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Effect on Sugar Levels
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0-80
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Increase
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Decrease
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Decrease
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above 80
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Increase*
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Decrease
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No change
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*Increase larger tuber size grades
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Table 2. Potassium fertilizer suggestions for potatoes.
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K Soil Test Level
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Soil Test Value, ppm
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K to Apply
lbs/acre*
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very low
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0-40
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120
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low
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41-74
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80
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medium
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75-124
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40
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high
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125-150
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0
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very high
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>150
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0
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*These amounts may be higher for table-stock and fry-stock markets, and lower for seed-stock.
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Table 3. Influence of potassium status on potato plant characteristics.
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Organ
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Deficiency
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Excess
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Leaves
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(early) dark - blue green
(later) overall bronzing
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none
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Younger
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small, cupped, curled down, brown specks (underside), crinkled, bronzed (upperside)
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Older
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bronzed to browning, spots between veins
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Stems
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stunted, short internodes
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none
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Roots
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poor growth
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none
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Stolons
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shortened
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none
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Plant or Soil Fertility Level
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Deficient
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Adequate
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Excess
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Small tubers
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Optimal-sized tubers
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Optimal-sized tubers
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High sugar levels
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Low sugar levels
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Low sugar levels
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Low dry matter
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High dry matter
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Low dry matter
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Few usable (fries)
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Many usable (fries)
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Most usable (fries)
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Many usable (chips)
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Most usable (chips)
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Few usable (chips)
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Mature tubers
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Mature tubers
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Mature tubers
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Disease susceptible
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Disease resistant
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Disease resistant
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