Agronomy Degree Practice Exam

Which soil type typically holds more nutrients and moisture for crops?

1. Sand

2. Silty clay

3. Sandy loam

4. Clay

The correct answer is: Silty clay

Silty clay is the most effective soil type for retaining nutrients and moisture, making it highly beneficial for crop growth. The composition of silty clay allows it to have a fine texture with a balanced mixture of silt and clay particles. This combination leads to a higher surface area, which enables the soil to hold onto water and nutrients more efficiently compared to coarser soils like sand or sandy loam. Because of its water retention capabilities, silty clay can provide crops with consistent moisture, which is crucial for their development. Additionally, the nutrient-holding capacity is enhanced by the clay fraction, which can bind to various nutrients, keeping them available for plant uptake. These characteristics contribute significantly to soil fertility and overall agricultural productivity. In contrast, other soil types, such as sand, have larger particles and spaces that lead to quick drainage, causing them to hold less moisture and nutrients. Sandy loam, while better than sand, still does not retain as much moisture and nutrients as silty clay. Clay, while excellent at holding moisture, can become compacted and difficult for roots to penetrate, sometimes leading to poor drainage. Therefore, silty clay emerges as the superior choice when it comes to supporting crop growth through its nutrient and moisture retention properties.