Certified Crop Advisor Practice Exam

Which of the following textural classes has the largest potential available water?

1. clay

2. sandy loam

3. silt loam

4. loamy sand

The correct answer is: silt loam

Silt loam is the correct choice because it has a balanced combination of silt, sand, and clay particles that maximizes its water-holding capacity while still allowing for good drainage. This textural class typically retains more water than sandy loam and loamy sand due to the finer particles that improve its ability to hold moisture. Clay, while it retains water very well, can become waterlogged, which may limit the availability of water to plants because of poor aeration. Sandy loam has a decent balance of drainage and retention but lacks the higher moisture-holding capacity provided by the silt. Loamy sand, containing a higher percentage of sand, tends to drain quickly and hold less water compared to silt loam. Thus, silt loam strikes an ideal balance that allows it to maintain the largest potential available water for plant use, making it advantageous for agricultural practices.