Clay
Definition
Clay consists of the smallest soil particles (<2 μm) with a large surface area for nutrient adsorption. Different clay types vary in properties, but all can hold essential nutrients like magnesium, potassium, and calcium, making clay crucial for soil fertility and plant growth.
Clay %
Clay (%) is the percentage of clay that is present in the soil. The presence of clay influences the soil texture. A higher percentage of clay increases the water-holding capacity and creates smaller pores which are beneficial for certain micro-organisms like bacteria and protozoa.
Clay/SOC ratio
The clay / SOC ratio is an indicator of the structural condition of the soil. Generally, the soil structure quality increases with a decreasing clay / SOC ratio. A clay / SOC ratio of 8:1 is an average for a very good structure quality, whereas a clay / SOC ratio of 13:1 or higher is less favourable (Johannes et al., 2017) .
