Certified Crop Advisor Practice Exam

The depth of sampling no-till soils as compared to conventionally tilled soils is _______?

1. Deeper

2. Similar

3. Shallower

4. More variable

The correct answer is: Shallower

In no-till systems, the primary focus is on maintaining soil structure and minimizing soil disturbance, which is different from conventional tillage practices. This results in the rooting zone and organic matter being concentrated in the upper layers of the soil profile due to the retention of surface residue and minimal disruption of soil horizons. Consequently, when comparing the depth of sampling for no-till soils, it is typically shallower than conventionally tilled soils. In conventional tillage, the process of plowing and turning the soil creates a more uniform and deeper cultivation zone, which can lead to a more extensive root system and organic matter being mixed throughout the soil profile. Therefore, sampling in conventionally tilled soils might encompass deeper layers to capture this mixing and potential stratification effects. Overall, the unique characteristics of no-till systems, focusing on surface layer retention, result in shallower sampling depths compared to conventionally tilled soils where disturbances promote deeper sampling.