FREE Certified Horticulturist Soils and Media Questions and Answers
Which soil texture has the highest water retention capacity?
Clay particles are the smallest in size and have a high surface area, allowing them to retain water effectively. However, clay can also hinder drainage. Loam, while a balanced texture, doesn’t hold as much water as pure clay.
What is cation exchange capacity (CEC) in soil?
CEC refers to the soil's capacity to retain positively charged ions (cations) like potassium, calcium, and magnesium, making them available to plants. High CEC indicates a fertile soil rich in nutrients.
What is the ideal pH range for most horticultural crops?
Most horticultural crops thrive in slightly acidic to neutral soil because nutrient availability is optimal within this range. Some plants, like blueberries, prefer more acidic conditions, but the majority fall within 5.5–7.0.
Which soil amendment is best for increasing drainage in heavy clay soil?
Perlite is a lightweight, porous material that improves drainage by increasing air spaces in heavy soils. Compost and peat moss improve organic content but may not significantly enhance drainage in clay soils.
Which component of potting media provides aeration and prevents compaction?
Sand is often added to potting media to increase aeration and prevent compaction, especially in soils prone to waterlogging. Peat moss and coir help with water retention rather than aeration.