As the diagram to the left indicates, even if you have certain micro- or macro-nutrients present in your soil in sufficient quantity, if the pH is too high or too low, the nutrient will be “locked up”, that is, unavailable to the plant.
The majority of our crops prefer to grow in slightly acidic soil, between 6.2-6.8, with a few exceptions. It is relatively easy to decrease the acidity of soil (raise from pH 5 to pH 6) though the use of limestone, which is very basic (meaning it has a pH higher than 7.0). Lime is incorporated into the soil and in a relatively short period of time begins to increase soil pH.
Lowering basic soil to neutral or acidic is a more difficult challenge. Sulfur, and sulfur compounds, can be added to the soil to increase acidity, but the change happens very slowly and often a lot of material needs to be incorporated.
Extreme pH plant preferences include a few economically important crops.
Crops that prefer acidic soil: Blueberries (and their relatives) pH4.5-5.5, Asparagus
Plants that can grow in basic soil: Alfalfa
With that said, consider the pH preferences of your desired crops and the pH of your soil. Is it feasible to alter your soils to match your plants, or should you choose another crop?