mortiz085

Potassium (K) is second to nitrogen in terms of the amount absorbed by higher plants. Optimum K level for plant growth ranges from 2 to 5% of plant dry weight (Marschner, 1995). Unlike P, K is present in relatively large quantities in soils coming from the weathering of primary minerals such as feldspars, mica and others. But it is commonly deficient in highly weathered or old soils. Total K contents of soils range between 3000 and 100,000 kg/ha in the upper 20 cm of the soil profile (Sparks, 2000). The behavior of K in the soil is influenced primarily by CEC and mineral weathering and not by biological processes. Interrelationship of various forms of soil K (modified from Sparks, 2000) K in the soil occurs in 4 forms: solution K, exchangeable K, nonexchangeable K, and mineral K (Sparks, 2000). a) Solution K . This is the K dissolved in the soil solution. It is the form of K that is readily available to plants and soil microorganisms and also is the form of K most subject to leaching