Soil pH

Soil pH quantifies the hydrogen ion concentration in the soil solution on a logarithmic scale from 0 (most acidic) to 14 (most alkaline), with 7 being neutral. Most crops grow best in a slightly acidic to neutral range of 6.0–7.0, where essential nutrients are most readily available. When soil pH drops too low, toxic levels of aluminum and manganese can harm roots, while high pH can lock up iron, zinc, and phosphorus. Soil pH is measured through laboratory soil tests and is the starting point for fertility recommendations. Lime application is the primary method used to raise soil pH in acidic soils.