For a backyard organic gardener the answer is probably not; for a commercial grower with acres under cultivation, soil testing should be done. Many gardeners may disagree and find soil testing valuable, but I’ll tell why I don’t send soil to a lab for testing.
When labs test soils they do a titration which involves pouring an acid over the soil and testing levels of elements that filter out. Different labs use acids of different strengths so results could vary. And plant roots don’t have those acids available to them to break down soil into a form plants can use. Plants grow by osmosis. Water carries the nutrients to the growing plant. So the numbers shown in a soil test doesn’t mean that enough of that nutrient will be available to a plant. Temperature, bacterial activity, moisture level and soil structure all have an impact on what nutrients will be available. There is much more to growing good crops than soil test numbers.
With the numbers from a lab come recommendations. If the lab recommends adding potassium, are you going to find an organic source of potassium that doesn’t contain anything else? Not likely. But good compost will provide potassium. It will also improve soil structure whether the soil is sandy or clay. Compost also provides microbes that will enable plants to take up nutrients. A shot of aerated compost tea will also provide beneficial microbes. Plants grown with good organic methods usually find the nutrients they need.
A shovel is a great tool for soil testing. If one can go in easily to depth of a foot and show all dark topsoil when turned, it’s good soil. If a shovel hits hard clay and rock at a level of 2 inches, building raised beds and hauling in topsoil or compost is likely a good idea. A really determined gardener who wants a lot of exercise double digging could work with “soil” like that, but it won’t be easy.
A lab soil test will show what nutrients are in soil. But it won’t always correlate to what is available to a plant. Good organic practices generally provide a plant what it needs. If you add lime in the fall, provide a good root zone, incorporate compost, and spray compost tea, good results are likely.