At which soil test level would you expect to see the greatest crop response?

The greatest crop response is typically observed at low soil test levels. When nutrient levels are low, crops are more likely to exhibit a significant response to fertilizer application or soil amendments because they are in need of those essential nutrients for growth, development, and yield.

At low soil test levels, the nutrient availability is inadequate for optimal plant growth, which can lead to nutrient deficiencies and adversely affect crop performance. Therefore, when fertilizers or amendments are applied in these conditions, the crops can significantly increase their growth and yield as they now have access to the necessary nutrients they were previously lacking.

In contrast, at high, medium, or very high soil test levels, crops are generally already receiving sufficient nutrients, which lessens the likelihood of a dramatic response to additional inputs. As soil fertility improves, the incremental benefit gained from further fertilization diminishes, leading to a decreased response compared to what would be expected in low nutrient conditions. This is why targeting low test levels is crucial for maximizing crop production efficiency.