Twenty-five years ago I made some thriving little vegetable gardens by
digging 4 x 4 holes two feet deep and using a lot of compost when I
filled them in.

I moved away. Ten years ago I moved back and built a new garden near
where the others had been. It has never worked very well.

Tomatoes are an example. Each year the plants seem to be doing well
until the first fruits are big and green. Then, branch by branch,
leaves begin to shrivel and fall, and I won't get any more big fruit.

What could be wrong?