The biological aspect of soil fertility is similar to a busy community below the surface, where microorganisms, fungi and other tiny life forms help nutrient cycling. Key indicators of biological soil fertility include the presence and activity of micro-organisms such as bacteria and fungi. These microscopic organisms break down organic matter, releasing nutrients for plant uptake. Earthworms, another key indicator, improve soil structure and nutrient distribution through their burrowing activities. The diversity and abundance of these soil organisms are vital signs of a thriving and biologically fertile soil. Monitoring and maintaining this invisible biodiversity are essential practices for cultivating a soil environment that supports vibrant and healthy ecosystems.