Only a few of the metals, such as iron, benefit from the addition of chelate. Also, a SAR or ESP should be done for alkaline or sodic soils. Testing for secondary and micro nutrients is usually not needed and is expensive to conduct. A current list of testing facilities can be requested from the Cooperative Extension office. Home soil testing kits are not as accurate as lab testing.
Some kits are very poor.
More expensive kits are not necessarily more accurate. How to Take a Soil Sample Obtain cartons and information sheets from your county agent, the state soil testing laboratory, or other sources. Map the different areas within a field - such as hilltops, midslopes, bottomlands, or known areas of different productivity. With a sampling tube take 10 to 15 cores, spaced an equal distance apart. Sample to tillage depth.