Potassium in soil is available to the plant as a salt.
Potassium is an essential element for plants . Carbohydrates form only when potassium is readily available and is apparently essential for starch formation. Potassium is needed for meristematic activity.
Symptoms on broadleaf plants are marginal and interveinal chlorosis followed by scorching inwardly between the main veins to include the entire leaf, starting with older leaves; leaves may crinkle and roll upward. Shoot tips die back late in the season; shoots from lateral buds have a zigzag growth that is short and brushy. Few flower buds form. Fruit is small with poor color.
Symptoms on Conifers are the oldest foliage is dark blue-green, progressing to yellow and reddish-brown necrosis occurs finally at needle tips. Needle retention is poor with needles stunted. Short, thick, and abundant buds form. Frost injury is common