Texas FFA Nursery Landscape Practice Exam

Why should freshly cut bark chips and sawdust be avoided as soil amendments?

1. Release toxic elements into the soil

2. Hold too much water around the plant

3. Rob the soil of nitrogen during decomposition

4. Infested with disease

The correct answer is: Rob the soil of nitrogen during decomposition

Freshly cut bark chips and sawdust should be avoided as soil amendments primarily because they can rob the soil of nitrogen during decomposition. When organic materials like bark chips and sawdust are added to the soil, they undergo a process called microbial decomposition. This process requires nitrogen to be carried out efficiently. Microorganisms that break down these carbon-rich materials consume nitrogen from the surrounding soil, which can lead to a temporary depletion of nitrogen levels in the soil. This depletion can adversely affect plant growth, as nitrogen is an essential nutrient for plants, playing a critical role in their ability to grow and develop. Insufficient nitrogen can lead to poor plant health, reduced vigor, and slower growth. The concerns associated with this nitrogen robbing effect highlight the importance of ensuring that any soil amendments contain a balanced ratio of carbon to nitrogen or that nitrogen is supplied separately when utilizing such materials. This awareness is key for gardeners and landscapers aiming to improve soil conditions without negatively impacting their plants.