Certified Crop Advisor Practice Exam

Which of the following is not an example of a contribution of soil organic matter to soil properties?

1. Increased Water Holding Capacity

2. Improved Soil Structure

3. Increased Molybdenum Availability

4. Nutrient Cycling

The correct answer is: Increased Molybdenum Availability

Soil organic matter plays a crucial role in enhancing various soil properties, and recognizing what it contributes is essential for understanding soil health and function. Its contributions include increasing water holding capacity, improving soil structure, and facilitating nutrient cycling. Increased water holding capacity refers to the ability of soil to retain moisture, which is vital for plant health. Organic matter acts as a sponge, allowing the soil to hold onto water and making it available to plant roots over time. Improved soil structure is another critical function of soil organic matter. It promotes the aggregation of soil particles, which enhances aeration, water infiltration, and root penetration. This improved structure facilitates better movement of air and water within the soil, supporting healthy plant growth. Nutrient cycling, the process whereby nutrients are released, absorbed, and reused within the soil ecosystem, is significantly influenced by organic matter. It serves as a reservoir for essential nutrients, helping to make them available to plants over time. Conversely, while molybdenum is an essential micronutrient for plants involved in processes like nitrogen fixation and enzyme functions, the presence of soil organic matter does not directly increase the availability of molybdenum in the soil. This lack of direct relationship distinguishes it from the other contributions