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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