If you want to produce seriously nutritious food it all starts with your soil. One of the most important aspects of gardening is revitalizing that soil every single year. If you have a great year of growing and produce tons of fresh vegetables your soil is tired. Its going to need some help to get back into growing shape again. This article goes over several different ways to enrich your soil. It may sound complicating but its actually pretty simple.
The article also spends a bit of time explain just what soil enrichment is. It offers three variations to soil enrichment. I would recommend that you try to employ as many of these as possible. Also, look to create sustainable processes that will make these enrichments available to you each year. One of my favorite enrichments is composted chicken manure. It is renewable and also brings you eggs throughout the year.