Evaluate nutrients
Check soil test results for an even balance between nitrogen, phosphorus, and potassium, all necessary for strong tomato production. Evaluating nutrients will go a long way in preparing your soil because you will know what you need to add.

Nitrogen
Nitrogen helps your tomatoes maintain healthy, green leaves. Yellowed older leaves and slowed growth indicate nitrogen deficiency. But when you apply too much nitrogen before fruit is set, stems become quite large, leaves are deep green and soft, and there are few if any flowers. Tomatoes need about 1-3⁄4 pounds of nitrogen per 500 square feet. Incorporate nitrogen into soil just before planting.

Good organic fertilizer sources of nitrogen:

alfalfa meal
blood meal
compost
feather meal
fish meal
legumes
leaf mold

Good inorganic nitrogen sources:

ammonium nitrate
ammonium sulfate
anhydrous ammonia
calcium nitrate
potassium nitrate
sodium nitrate
urea

Phosphorus
Phosphorus helps your tomatoes develop strong root systems, build disease resistance, and cultivate fruit and seed formation. Slow, stunted growth and reddening stems and foliage indicate a phosphorus deficiency. Incorporate phosphorus-containing fertilizers into the soil before planting, rather than sprinkling them on the surface.

Good organic fertilizer sources of phosphorus

bone meal
compost

Good inorganic phosphorus sources

rock phosphate
super phosphate

Potassium
Potassium helps promote growth and disease resistance in your tomato plants. Weak plants and slow growth indicate a potassium deficiency. In more severe cases, leaf edges will brown. An easy way to amend the soil is to add wood ash, which is 5% potassium. Best rate is about 10-15 pounds to a 300 square foot bed. Work in wood ash in the fall or winter.

Good organic fertilizer sources of potassium

wood ash
granite dust (also called rock potash) � slow-releasing leaf mold

Good inorganic potassium sources

potassium sulfate
rock sand

Compost
Compost is broken-down organic matter. It�s not particularly high in nutrients but it�s a fantastic way to improve your soil. Compost improves soil structure, increases its cultivability, aids in nutrient retention, reduces compaction, attracts earthworms, increases microbes, and protects plants from disease. Adding compost is the singular most important step you can take to preparing your soil for planting tomatoes.

yellowing plants could also result from lack of potassium intake... I think a lot of folks over-look this.
it doesn't necessarily display it's self with browning tips.
therefore many people think of nitrogen deficiency.
that is not always the case