To answer your questions,
The pot is filled up to 16" high, width varies from 18" at the top of the soil level, 24" in the middle and 14" at the bottom. Frightfully sorry but I have no idea how to calculate how many gallons of soil are in the pot. I use professional grade. Harrell's fertilizer slow release fertilizer granules for all tropical plants 16-6-11.
This year we had an unusual amount of rain and I depended on it for watering.
Measuring the pot I found two more lemons one green, still in the plant, and this yellow one which has a funny mark.