context: Oats remove substantial amounts of nitrogen from the soil. They also remove phosphorus in the form of P2O5 at the rate of 0.25 pound per bushel (1 bushel  38 pounds at 12% moisture). Phosphate is thus applied at a rate of 30 to 40 kg/ha, or 30 to 40 lb/acre. Oats remove potash (K2O) at a rate of 0.19 pound per bushel, which causes it to use 15–30 kg/ha, or 13–27 lb/acre. Usually, 50–100 kg/ha (45–90 lb/ac) of nitrogen in the form of urea or ammonia is sufficient, as oats use about one pound per bushel. A sufficient amount of nitrogen is particularly important for plant height and hence, straw quality and yield. When the prior-year crop was a legume, or where ample manure is applied, nitrogen rates can be reduced somewhat.
question: What things does nitrogen in the soil influence?
answer: plant height