Qualified Applicator Certificate (QAC) Landscape and Maintenance Practice Test 2025 – Your All-in-One Guide to Exam Success!

The presence of earthworms is a strong indicator of soil health because these organisms play a crucial role in maintaining soil structure and fertility. Earthworms contribute to nutrient cycling by breaking down organic matter, leading to the formation of rich, fertile soil known as humus. They also help aerate the soil and improve its drainage, which enhances root development for plants. The presence of a healthy population of earthworms generally signifies a well-functioning ecosystem that is conducive to plant growth, making them a reliable bioindicator for assessing soil health.

In contrast, while high levels of nitrogen can be beneficial for plant growth, excessive nitrogen levels can lead to nutrient imbalances and environmental issues such as water pollution. Excessive water retention may indicate poor drainage and compaction, which can harm roots and decrease soil health. Soil color variation can provide some insights into soil composition and organic matter content but does not offer a direct measure of overall soil health like earthworm populations do.