Gypsum will help, and so does lime, to a certain extent. even though the soil may not nees lmie for the ph...
The other guys are right. what i did, was to start with a seed bed, adding sand and what we call leaf mulch, or triple ground hardwood mulch b y the two or hree inch at a time level. i grew corn and other morte "rank" plants on the "new " ground. Eacch year, I move my seed bed. As I abandon the previous yeear's seed bed, I plant squash, wich is kind of "Intermediate" as far as being able to tolerate clay soil. Next, peppers, then cabbage, broccoli, etc. Any way you slice it, it is a lot of work. Green manure like buckwheat helps more than you know. always till up you paces or plots and imediately plant buckwheat in warm weather, or wheat or rye in cold weather. It doesn't matter if buckwheat gets killed by a frost, just til it in and plant wheat or rye. i have heward barely is good this way, as well as something called Austrian winter peas. Soybeans are good like this. The moral to the story is nature hates a vaccum, and weeds will grow, and the soil will lose it's "tilth"or friability qwuickly if it isn't full of rotted and rooting plant matter, primarily roots. Keep something on it. our garden has a cover crop or gree manure on it as much or more than a food crop. Follow one kind of plant with another.
Tomatoea are easy to grow, even in bad soil. I plant mine with a post hole digger in stuff that is hard as a brick, and mulch very heavily with wheat straw, or rotten hay. I don't like hay because of the grass and weed seeds, but i 'll taker anything that is free.
Sawdust is a quick fix, but you will have to use more nitrogen than you would think, it consumse nitrogen when it breaks down. Leaves a re greeat, too. What to look for? worms, thousands of them. when your soil is healthy, worms will thrive there.
