Re: fertillizer in potted plant
The whole idea about planting tomatoes deeper came about because the starts were raised in hot houses, then sold to outdoor gardeners. In this situation the starts must be planted deeper because they are too weak to take the non-hothouse environment.
Now I guess that planting deeper as the article suggests would help in situations where growing area is limited. Certainly it is true for tomatoes that crop production is proportional to root volume. When customers want to grow a standard tomato in a pot I always recommend 1 plant in a 25 gallon pot. They look at me like I'm crazy, but after they try it and get 200-300 lbs of tomatoes per plant they start to understand.
When I plant tomatoes in my garden, they are 6-foot apart on center and the ground is heavily mulched so the roots can go deep and wide. 300 lbs per plant is typical.