I grew up on a farm in a clay belt. Growing vegetables need nutrients. Heavy feeders squash, cucumbers, tomatoes etc grow best in really rich soils. By rich I mean being planted in manure piles in the old days. Over the years (50 plus) and have lived on many different soils and the one thing that is most important is getting a very high level of organic matter incorporated into the soil. How do you think that black soil gets to be black? Guess what organic matter. When organic matter is worked into the soil in the fall it decomposes over the winter. One place I lived had a clay soil and I could not put enough organic material in it to make it into a really good soil before I moved (5 years). The bottom line is plants don't like to grow in clay soils,
Bacterial levels (goggle clay). Never mind the composting etc just get any and all organics worked into the soil. As the organic level builds up all good things will come to enjoy your soil.