Overview
Potassium is an essential component of plant nutrition. Potassium deficient plants are known to be less resistant to plant diseases.
Key functions in the plant
Maintenance of water balance in the plant, helps regulate cell water content and plant turgor, maintaining stem strength
Important role in transpiration by controlling stomatal pore opening and closing
Good mobility in the plant
There are 4 pools of potassium in the soil, most are in soil minerals. These weather to release slowly available potassium embedded in clays, readily available potassium held on the surface of clays, organic matter and potassium in soil solution
Factors affecting availability to plant
Low pH soils
Deficiency can be common at the end of the growing season, especially on light, sandy soils
Soils with low clay reserves where little K is released, and on sandy or light soils where K can be leached
Drought and high levels of magnesium reduce uptake