Amend with compost, rock dust and animal manure if available. You should have plenty of earthworms. Dead water soaked soils have no earthworms. Compost and mulching will increase organic matter to soil allowing bacterial and nutritional resources to increase. Practice soil rotation if possible.
Rotation of crops is suggested whenever possible.
If a raised bed is used allow the bed to go fallow for one season. Some Diseases are introduced by Viruses. Destroy diseased plants. Throw away in the trash. Do not compost since most backyard gardeners do not compost in big enough piles in which the temperature is high enough to kill the fungi.