Which of the following is an advantage of soil nitrate-nitrogen testing for corn and barley?

Soil nitrate-nitrogen testing is particularly advantageous for corn and barley because it indicates the soil's nitrogen supply ability. This testing provides valuable insights into the current levels of nitrate-nitrogen present in the soil at a given time, which is crucial for determining the potential availability of nitrogen for plant uptake.

For crops like corn and barley, which require adequate nitrogen for optimal growth and yield, understanding the nitrate-nitrogen levels helps farmers make informed decisions about fertilizer applications. This can lead to more efficient use of fertilizers, helping to maximize crop yield while minimizing environmental impacts.

While other options may have merit, they do not directly address the primary benefit of what soil nitrate-nitrogen testing reveals about the soil's ability to supply nitrogen, which is critical for making effective nutrient management decisions.