Don't fertilize
this fall unless necessary
October 13, 2005
Fertilizing and fall winterizing are just around the corner. You have
various forms and kinds of fertilizer to choose from, but first, make sure you
need to fertilize at all.
There are more and more fertilizers available than ever before. The one
that's right for you depends on your type of lawn and garden, the results you
want, time of year, how much money you want to put in it and personal choice.
Ask yourself: Do I really need to fertilize? And what type of fertilizer
should I use?
Fertilizer is a substance used to make soil more fertile or more capable of
sustaining abundant plant life. According to
Plants, like people, must have nutrients to flourish. They need a balanced
diet with all of the necessary nutrients readily available for their use.
Plants will grow at optimum rates if nutrition is furnished as needed.
Keep in mind that the major pollutant of groundwater is nitrate, which can
come from plant fertilizer applications. That's why using slow-release
fertilizers to feed plants makes sense. Fertilizers
that gradually feed plants are not only environmentally sensible, but they also
enable plants to grow at optimum rates.
A recent soil sample survey conducted by Victoria County Extension through
the Master Gardener program indicates what Victoria County Extension Agent Joe
Janak has been saying for years now: "Start by collecting a soil sample,
have your soil tested and apply only the amount of nutrients needed. Too many
people over-apply nutrients to their plants. It's easy to do but hard to
undo."
In a recent sampling of about 30 samples collected, 22 percent of the
samples were either high, very high or had excess amounts of phosphorus and 74
percent of the samples were either high or very high in potassium. Even one
organic gardener in the program had excess levels of nutrients. When nutrient
levels are too high it can cause increased thatch in turf grass, increased
insects and diseases, and even decreased availability of other nutrients,
resulting in poor plant growth. All this can evolve into death of plants and
pollution.
According to Janak, "Through Extension and the Victoria County Master
Gardener program, we have four years of data now with over 300 soil samples,
and the trend is still the same - a high percent of the landscapes are
over-fertilized."
As a result, we may need to skip fertilizing some sites for three to five
years or only apply nitrogen fertilizers as the tests recommend.
If fertilizers are needed, they are available as solids, granules, powders
and liquids. The most common or familiar fertilizers are in the form of
crystals or granules. These are scattered on the soil and watered in. The
irrigation dissolves them and carries them into the soil. Other fertilizers are
liquids or soluble powders that are dissolved in water before application. They
can be applied by a water hose attachment, water can, or through an automatic
watering system attached to a drip irrigation system.
Fertilizers can be applied as solid chunks that are placed in the soil where
the plant root can reach them. They may or may not always be slow-release
fertilizers and come in the form of spikes, pellets, briquettes and coarse
salts.
Nutrients can also be applied in the form of organic matter. Manure is the
ancient source of plant nutrients. Compost, dead leaves, and other forms of
organic matter also decay to release plant nutrients. Organic matter improves
soil structure and adds nutrients. There is little or no chance of plant
burning and it lasts a long time.
The word "organic" means that the nutrients contained in the
products are derived solely from the remains or by-product of a living
organism. Cottonseed meal, blood meal, bone meal, hoof and horn meal and all
manures and composts are examples of organic fertilizers. Most of these
products packaged as fertilizers will have the fertilizer ratios stated on the
package labels just like synthetic fertilizers.
Some organic materials are sold as soil conditioners and do not have
nutrient guarantee even though small amounts of nutrients are present. Because
organic fertilizers depend on soil organisms to break them down and release
nutrients, most of them are only effective when the soil is moist and soil
temperature is warm enough for the soil organisms to be active. In our area the
microorganisms are active most, if not all the time.
Soluble synthetic fertilizers are produced by chemical reaction, from
organic or inorganic materials. These fertilizers release nutrients into the
soil quickly and deliver a fast greenup.
They are readily available because they do not depend on microbes, like
organic fertilizers do. This means they can deliver at critical time periods,
with known effects. These fertilizers demand more work. Their effects are
shorter-lived, so they require more applications. Also, the high salt content
of soluble synthetics adds the possibility of fertilizer burn. Always follow
recommended rates, apply to a dry lawn and water in thoroughly to avoid
burning.
After years of using a 3-1-2 or 4-1-3 ratio fertilizer, many landscapes have
an excess of phosphorus and potassium. Besides waiting for a disaster to alert
you, such as grass or plant problems, you should first test soil. Stop by the