Grapes growing in loam alluvial soils of Aconcagua Valley (central Chile) frecuently show potassium deficiency symptoms in spite of potassium fertilizer applications. A Laboratory study was conducted to determine potassium fixation of these soils. Potassium fixation were 48%, 66% and 72% by soil samples collected at 0-30 cm, 20-60 cm and 60-90 cm depth, respectively. Clay minerals identified were clorite, montmorillonite and illite. Among these, illite and possibly montmorillonite and its K saturation degree can explain the high fixation determined. |