" These minerals grab soluble plant nutrients like NPK and micro-nutrients when available in excess, because they have charged surfaces".
The clay minerals generally have a negative charge so they would attract the positively charged ions (cations). That's why nitrogen in nitrate form tends to leach more (negative charge) than ammonium nitrogen (positive charge). The major cations would be potassium, calcium, magnesium and sodium. Phosphorus has a negative charge as does sulfur. The micronutrients are a mix of positive and negative.
