Soil Testing: Finding Out What Your Lawn Is Actually Short Of

Most fertilization programs in Florida are built on assumption rather than measurement, and in soil that varies as much as ours does, that is a genuine waste.

What a test tells you

• pH. The most important number, because it determines whether nutrients that are present are actually available to the plant. Iron in particular becomes unavailable at high pH, which is why so many Florida lawns look yellow while having plenty of iron in the soil.
• Phosphorus and potassium levels. Applying phosphorus a lawn does not need is both wasted money and, in Florida, a regulated matter in some areas.
• Micronutrients, including magnesium and iron.
• Organic matter, which in sandy Central Florida soil is frequently very low and is the thing most worth improving.

Why sandy soil changes the answer

Sand holds neither water nor nutrients well. Nutrients applied heavily leach through before the plant uses them, which means the correct approach here is lighter and more frequent rather than heavy and occasional. A soil test tells you where to start; the soil type tells you how to deliver it.

Yellow does not mean nitrogen

This is the most common misreading. Yellowing between the veins on newer growth is usually iron, and iron chlorosis in Florida is nearly always a pH problem rather than an iron shortage. Adding nitrogen to that lawn produces more yellow growth.

Uniform pale yellowing across older growth is more likely nitrogen. The pattern matters more than the colour.

What to do with the result

Correct pH first where it is out of range, because everything else depends on it — and pH correction is slow, so it needs starting before the season you want the result in. Then build the fertilization program around the actual deficiencies rather than a bag that says it is for lawns.