Each spring, how many of us head out to the garden, till it upand add the same fertilizers we have been using for years? We complete our planting, and assume we're done. But as the season moves forward, and we begin to harvest our crops, something just doesn't look right. The yields are not as large as in the past; the taste isn't as good. I wonder what's going on?

Is your garden soil is getting tired? Perhaps the nutrient levels are not what they used to be; maybe the soil is not holding the moisture as it once did. What can we do?

I like to compare healthy soil the same way we determine problems with the human body. We can diagnose the problem using various testing procedure, and then set about working on a cure.

Don't Guess, Soil Test!

I have always been a strong advocate of soil testing. The majority of our land grant universities provide soil testing at a very reasonable price. In my area Michigan State University also provides fertilizer recommendations along with the test results. There are also a number of independent laboratories that will provide soil testing for home gardeners. I don't recommend the "do it yourself" kits as I feel the results are unreliable.

So to begin, I urge you to get a soil test before embarking on any manipulation to your garden soil.

Plants need 16 elements from which to grow and develop. These are hydrogen, oxygen, phosphorus, potassium, magnesium, nitrogen, sulfur, calcium, iron, carbon, boron, chlorine, manganese, molybdenum, copper and zinc. Three of these elements do not originate from soil mineral compounds. Hydrogen and oxygen come from soil and water. Carbon comes from the carbon dioxide in the air. Deficiencies of any of the above can affect plant performance.

Amend, amend, amend.

The best way to maintain healthy soil is by adding organic material. Compost, grass clippings, shredded leaves, straw, and manure are just a few items that will help build healthy soil.

A friend of mine moved into a new home where all of the top soil had been stripped away, leaving hardpan clay in the garden area. He began an organic material program consisting of sand, organic material, compost, grass clippings, leaves, pine needles, alfalfa meal. In just two years he has created a garden consisting of loamy, fertile soil. His latest soil test showed a balanced garden soil suitable for all types of vegetables; all it took was a little hard work and patience.

Cover that soil!

Cover crops, sometimes referred to as green manure, are another excellent way in which to help regenerate your soil. A cover crop is any one of a variety of plants whose primary purpose is to enrich the soil, prevent soil erosion, deter weed growth, and improve soil fertility. Most of the plants used as green manure are in the legume families which are high in nitrogen, beans, peas, lentils etc. The primary objective in using these types of plants is to replace the nitrogen consumed by the previous crops.

Cover crops are also an excellent way to suppress weeds; this is accomplished in two ways. During the growth cycle they compete with weeds for available moisture, space, light, and nutrients. After the cover crop dies, it forms a thick mulch layer thus smothering the weeds.

Two years ago I planted white clover as a cover crop around my tomato plants to prevent weed growth, and replenish nitrogen in the soil. I am happy to report that this has worked out really well. My tomatoes are thriving and there is almost zero weed growth. White clover is also a perennial returning year after year. One of the best sources for cover crops is Johnny's Selected Seeds; they have a large variety from which to choose. Some suggestions for cover crops are annual ryegrass, buckwheat, field peas, hairy vetch, mustard, oats, clover, wheat, and rape seed.

We all know that crops should be rotated on a regular basis in order to avoid depleting the soil of nutrients. Many gardeners do not have the space to do this.

This year I'm going to try an experiment. I garden on a typical suburban lot, and have limited space for a vegetable garden. My main crop is heirloom tomatoes. I have been growing them in the same location for years. This coming season I am going to seed my entire garden area in white clover. All of my tomatoes will be grown in straw bales on top of the cover crop. What do I hope to accomplish? I hope to give my soil a so called "rest" for a season or two in order to replenish essential nutrients that have been depleted over the years. I expect that a soil test next year will result in elevated levels of "good stuff" in my soil. I'll keep you posted.

To sum it up, get a soil test to see where you stand. Add organic materials--you can never get too much of them. Plant cover crops to enrich your soil. You won't be disappointed.