Certified Crop Advisor Practice Exam

Which soil structure is most conducive to good internal drainage?

1. Clayey

2. Blocky

3. Granular

4. Plate-like

The correct answer is: Blocky

The most conducive soil structure for good internal drainage is granular. Granular soil structure consists of small, crumb-like aggregates that create spaces between them. These spaces allow water to move freely through the soil, facilitating good drainage. Granular structures enhance porosity and air movement, which are essential for healthy root development and moisture management. This type of structure minimizes compaction, allowing for effective infiltration and reducing the risk of waterlogging. In contrast, clayey soil structures are dense and have very small particle sizes, leading to poor drainage as water moves slowly through the tight spaces. Plate-like structures tend to compact easily and do not allow for good water flow, while blocky structures, though better than clayey and plate-like, still do not match the drainage efficiency of granular structures due to their angular particles which can create uneven water movement.