June 25, 2008

Soil, Not Dirt, is Chock Full of Nutrients That We Can Help Replenish?

By Rick Sandella

Soil, the environment in which plants live, is not dirt. Soil is actually a complex ecosystem with physical, chemical and biological components that together assure that your plants will thrive with support from you.

Through the miracle of photosynthesis, plants feed themselves by converting the sun's energy into sugars that they use to grow and stay healthy. Because of photosynthesis, we do not need to feed plants (give them food) but rather we can provide them with the nutrients to help them thrive if there is a deficiency.

At the physical level, soil is roughly 50 percent solid material (minerals and organic matter) and 50 percent water or air.

The air-water percentage varies by season and amount of precipitation. Air and water are essential to plant health and the solid material, particularly the organic matter, holds water and can make many nutrients in the soil available for plants.

Plants require 16 different chemical elements to thrive. The major elements, carbon, oxygen and hydrogen, are provided through air and water.

The other elements, most importantly nitrogen, phosphorous, potassium, calcium, magnesium and sulfur are in the soil naturally.

If there is a deficiency, we can remedy that with fertilizer. The best way to determine if your soil is lacking any of the essential elements is with a soil test. It is a waste of your money and potentially environmentally damaging to fertilize without knowing if there is a problem.

Doctors do not write drug prescriptions without knowing the physical condition of the patient, and we should treat our soil the same way.

In some cases, all the necessary elements are in the soil, but the soil pH (acidity or alkalinity) inhibits the plant from using them. Correcting the pH with lime or sulphur is much more effective than fertilizing.

Soil tests are easy, inexpensive and can be done relatively quickly. For specific information, visit http:// www.soiltest.uconn.edu/ or call the University of Connecticut Cooperative Extension Office for New Haven County at 407-3168 or e- mail [email protected]

The Connecticut Agricultural Experiment Station also does soil testing. Visit http://www.ct.gov/caes/cwp/view.asp?a=2836&q=378206 for more information.

The third part of the equation that ties the soil story together is the biological component. Each handful of soil contains billions of microorganisms and almost all of them are beneficial to plants. Included in this population are fungi, bacteria, protozoa and tiny roundworms, which we cannot see without magnification.

They all play an important role in breaking down organic material to make nutrients available to plants. Although some of these living organisms can injure or kill plants, it is a very small percentage and they rarely harm healthy plants.

To assist plants, it is important that we nurture this life in the soil. We can do that by incorporating organic material such as compost into the soil, using slow-release natural or organic fertilizers and, if it is necessary to use pesticides, choose the least toxic one.

Harsh chemicals can disrupt the balance in the soil ecosystem and sometimes hurt, rather than help, your plants.

Contact UConn master gardeners Judith Hsiang and John Cox at 407- 3168 or [email protected]

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