Some types of nitrogen are available in greater quantities than others. For example, a lot of urea is manufactured globally. This means that there is a lot more availability and options to purchase urea from other sources. However, nitrate-based types of nitrogen are less available, especially liquid nitrogen. In those cases, other products such as urea are chosen. This is an effect we are seeing in the current situation.
On October 5th, 2022. See this statement in context.