Go to the garden center and pick up a bag of fertilizer. The biggest description on the label is likely to include the percentages of NPK, three vital nutrients that plants need to sustain life. Nitrogen, phosphorus and potassium were first described as the building blocks of every plant's life in 1840 by chemist Baron Justus Von Liebig in his publication, ''Chemistry in Its Application to Agriculture.''
Somehow, after the discovery of NPK, the extreme workings of our soil were believed to be limited to these three chemical compounds. Nitrogen is important to the growth of plants because it is one of main components of chlorophyll. Without chlorophyll, plants would not be able to use photosynthesis to create food. As every school child learns in elementary biology, photosynthesis is the process by which plants use sunlight and carbon dioxide to produce sugars. Nitrogen also is a large part of amino acids in proteins, not to mention nucleic acids, which if that word sounds familiar, it is because it's the "n" in DNA.
Phosphorus in the soil promotes strong root growth. When gardeners sprinkle their planting beds in the spring with triple super-phosphate, they are encouraging strong root growth for plants that have been asleep over the winter. Phosphorus also helps plant roots absorb water more easily and stimulates seed and flower formation.
Potassium, identified with the symbol "K," is the protector. It helps plants fight off diseases and enables them to better handle extreme temperature changes and periods of drought. Potassium is important to the production of starches and helps plants regulate their water intake.
For many years, farmers and gardeners were led to believe that as long as we had NPK, our plants would be happy and healthy. While it's true these three elements are important to plant growth and longevity, there are many more things that are equally important.
We can't limit our gardening thinking to only NPK. Just as important to our plants' growth are things like calcium, sulfur and magnesium. In fact, scientists have identified no less than 17 crucial building blocks for our plants and there are many more out there not yet discovered. Also unknown to science is the way these nutrients interact with each other. They all work together to perform their related tasks. Three alone won't do it all.
Over time, well past the era of Von Leibig, important trace elements were discovered that include among other things, boron, copper, manganese and zinc.
The good thing is, unless you are looking toward a degree in chemistry, you don't have to memorize them all. You don't have to invest in a microscope, nor will you have to set up a laboratory that resembles Dr. Frankenstein's.
What you can do to ensure healthy garden soil is to add organic matter and the best organic matter is compost. It is better than synthetic fertilizers because compost is alive, just as your soil is alive. The living organisms in composted plant material do many things for your garden, including things like:
l Neutralizes soil PH;
l Enables plants to use the nutrients gradually as they are needed rather than one quick boost and the rest washing away as chemical fertilizers do; and
l Alters the soil structure, loosening clay soils so that water and oxygen flow easily to the plants' roots where they are needed.
Compost also helps feed the living organisms in soil, allowing them to feed on the decaying plant material and leave behind their own plant nutrients, including breaking down nitrogen so that plants can absorb it readily. Compost is not the only organic way to fertilize your garden soil.
Nitrogen can be added by using composted manure, blood meal, fish powder and compost tea. Organic phosphorus sources include rock phosphate, bone meal and fish emulsion. An organic source for potassium is green sand.
Basically, we need it all. We need NPK, but we also need micro nutrients, living things like earthworms and soil bacteria and soil amendments. We need oxygen and water and sunlight. The good part it, it is all available to us, right here on our earth.
We just have to remember that what we take out, we need to give back. Hopefully we can do it as naturally as possible.