I have a large area of miserable clay soil which I'm looking to start rehabilitating. For the past 15 years it's been neglected and had nothing but some unwanted grass. It's very compacted due to driving machinery over it this summer to build a retaining wall.
At the moment I am (slowly) going through and loosening the soil with a combination of shovel and broadfork. At the same time I'm turning in the fall's crop of fallen leaves and apples from our yard to start adding something more than clay.
After it's loosened, I'm thinking of buying night crawlers and adding them to the soil to help continuing to loosen it up. Is it worth it (e.g. will they make a difference)? If so, is there any guidance as to how many worms (it's about 1,000 square feet)?