What is indicated if a clod fails under strong pressure between thumb and forefinger?

When a clod of soil fails under strong pressure between thumb and forefinger, it indicates that the soil is hard. This refers to the compactness and resistance of the soil structure. A hard soil requires considerable force to deform or break apart, which suggests that the soil particles are tightly packed together, resulting in limited airflow and water movement.

In the context of soil evaluation, understanding the firmness of the soil is crucial for determining its potential for root penetration, drainage capacity, and overall health for plant growth. A hard soil can lead to issues such as root obstruction and poor water infiltration, affecting agricultural practices and land use decisions. Recognizing the hardness of soil can guide soil management practices to improve its condition, such as through aeration or tillage.