In soil chemistry, what is commonly assessed to determine nutrient availability?

Soil pH is a critical factor in soil chemistry because it significantly influences the availability of nutrients to plants. Most nutrients are available to plants only within a certain pH range, which typically falls between 6.0 and 7.5 for many crops. When soil pH is too low (acidic) or too high (alkaline), several essential nutrients may become unavailable, leading to deficiencies that can adversely affect plant growth.

For example, in acidic soils, nutrients like phosphorus can become bound to soil particles and therefore less available to plants. Similarly, in alkaline soils, elements such as iron and manganese may become less soluble, leading to deficiencies. By assessing the soil pH, agronomists and agronomic advisors can make informed decisions about nutrient management and adjustments needed to optimize soil conditions for plant growth.

Other options like soil color, density, and temperature provide some insights into the soil characteristics but do not directly relate to nutrient availability in the way that pH does. Soil color can indicate organic matter content or moisture levels, soil density relates to compaction and porosity, and soil temperature impacts biological activity; none of these parameters offer as direct a measurement of nutrient availability as soil pH.