You will always find Dale, local meteorologist, at the KRIS TV Spring and Fall Home & Garden Shows in Corpus Christi. He has developed a formula famous in this area for growing tomatoes.
http://www.kristv.com/category/294095/dales-tomato-formula
There are two Tomato formulas... One formula for sandy soil and one for clay soil. The first time you use the tomato formula use the "Original" formula no matter what type of soil you have.
Original Formula / Sandy Soil
1 cup 10-20-10 (1-2-1 ratio) fertilizer
1/4 cup super phosphate
1/2 cup gypsum
2 cups cow manure
Dig a hole and mix ingredients. Then, add regular dirt on top of formula before placing tomato plant in hole. Otherwise, formula will burn the roots of the plant. Don't let formula touch the roots when they are first planted. Let the plant grow into the formula. Water regularly. Stand back and watch them grow! Best varieties are Sonny, Bingo, Carnival, Heatwave, Celebrity, Big Boy, Better Boy and President. Best cherry tomatoes to use are small Fry and Cherry Grande. Everything needed is available at any local nursery.
Caution: Please be aware that excessive use of phosphorus in our clay soil over a long period of time can be non beneficial to your plants.
Clay Soil*
1 Cup 21-0-0 (1-0-0 Ratio) Ammonium Sulphate
3/4 Cup Gypsum >p> 2 Cups Cow Manure
Mix these ingredients together with existing garden soil and plant one tomato plant per hole mixture. *Most clay soils in this area already have too much super phosphate, which tends to stay in the soil for a long period of time. The local nursery people tell me, the best way to correct this is by adding ammonium sulphate which is 21-0-0.cc