Soils 205- General Soils

Lecture 28- Potassium

I.  Potassium- K is an essential nutrient that plays a role in enzyme activation, water relations, phyotosynthesis, and N fixation.  Additionally, good K nutrition helps plants adapt to environmental conditions (frost hardiness, drought tolerance, disease resistance, etc.)

     a.  Aspects of K in soils

    -present in soil solution only as K+

    -no gaseous form

    -cycle is controlled by cation exchange and mineral weathering, not microbial transformations

    -K doesn't cause off-site environmental damage

    b.  Problems with K nutrition

        -most K is found in forms that are unavailable to plants

        -leaching (especially in acid, sandy soils)

        -plant uptake/luxury consumption

     c.  K "pools"

    d.  The K cycle

    e.  summary- sources and sinks of K