Provide your best answer for the following question. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The question is: Overuse of soil for farming causes local disruptions of several Earth subsystems. Which of these is a part of the biogeochemical cycle that experiences the most severe local disruption?
cycling phosphorus into the soil
Nitrogen cycle.