Baked clay soil

It has formed a hard crust that will cause any rain/water to simply run off rather than soak in.

Best to get the hoe out and pretend you're weeding to break up the crust everywhere. this will both let in more air plus let any rain soak in easily. Once you hoe up the soil, some mulch would be a good idea to keep the crust from reforming and to trap in any moisture. Use whatever you can get - straw, leaves, compost, old grass clippings, etc.  If you do nothing, then the dryness will stress the plants which will attract more pests.