Gotta agree with Bill on this one. Rotating is the "best" method. Putting a cover crop down of a Non grass species will help break the cycle up. Rye and wheat cover crop won't put Nitrogen in the ground,,,but it does utilize any left over N and that becomes available when plowed under the following year. Legumes will put N in the soil, but the bigger benefit is that the root system and organic matter loosens the soil tremendously. If you want really flavorful veggies, build up the humus(organic matter) in your garden. It is a slow process, no miracle cures out there...but well worth it..Good luck Greg