Potassium Tables

Table 1. Potassium efffects on yield and process quality.

 
 

K Rate
lb/acre

Effect on
US #1 Yield

Effect on % Dry Matter

Effect on Sugar Levels

0-80

Increase

Decrease

Decrease

above 80

Increase*

Decrease

No change

*Increase larger tuber size grades

 

 

 

 

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 Table 2. Potassium fertilizer suggestions for potatoes.

 
 

K Soil Test Level

Soil Test Value, ppm

K to Apply
lbs/acre*

very low

0-40

120

low

41-74

80

medium

75-124

40

high

125-150

0

very high

>150

0

 

*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.

 
 

Organ

Deficiency

Excess

Leaves

(early) dark - blue green
(later) overall bronzing

none

Younger

small, cupped, curled down, brown specks (underside), crinkled, bronzed (upperside)

 

Older

bronzed to browning, spots between veins

 

Stems

stunted, short internodes

none

Roots

poor growth

none

Stolons

shortened

none

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Table 4. Influence of potassium status on harvested tuber characteristics.

 
 

Plant or Soil Fertility Level

Deficient

Adequate

Excess

Small tubers

Optimal-sized tubers

Optimal-sized tubers

High sugar levels

Low sugar levels

Low sugar levels

Low dry matter

High dry matter

Low dry matter

Few usable (fries)

Many usable (fries)

Most usable (fries)

Many usable (chips)

Most usable (chips)

Few usable (chips)

Mature tubers

Mature tubers

Mature tubers

Disease susceptible

Disease resistant

Disease resistant