Friday, March 2, 2012

What do those-those-those numbers mean?

"Gardeners know the best dirt."


Purple Stock

Apricot Blossom
 Although some of you are garden experts, I have to admit I'm totally clueless when it comes to understanding those mysterious numbers-numbers-numbers on the fertilizer and plant food bags. I see people in the store importantly reading those numbers and I wonder if it's a secret club, where you learn the unlock codes if you join.Well, I wanted to be a member, so welcome to learning those secret codes and what they mean.
In addition to light, air, water and growing space for roots, plants need a supply of nutrients. Most of these are provided by the soil. But there are three major nutrients that plants need in larger amounts for consistently good growth. They are:

Besides these top three nutrients, there are six minor nutrients essential to plant health. When poor growth reveals a deficiency, you'll have to add it in form of a fertilizer. Let's look at each one.

NITROGEN- Nitrogen is not naturally found in soil, but rather comes from decomposing organic matter, air or fertilizers. Rainfall can carry nitrogen from the atmosphere into the soil; but conversely, it can also leach nitrogen from the soil in a rainstorm due to run-off.

Plants use large quantities of nitrogen to form proteins, chlorophyll and enzymes needed for plant cells to live and reproduce. When nitrogen is low, leaves yellow from their tips toward the stem, the plant yellows from the bottom upward, and the growth is stunted.Many plants need supplemental nitrogen from time to time in order to grow as well as we wish they would.

The first of three numbers shown on a fertilizer label indicates the percentage of nitrogen. In the natural course of nature (without fertilizer) nitrogen that comes into the soil as either dead animal or plant material must undergo several changes before it becomes the nitrate form that plants can use.

Here is where it pays to read your fertilizer or plant food label! If a fertilizer's label says that all or most of the nitrogen contained is in either nitrate or nitric form, nitrogen will be released quickly and plants will be able to use it immediately. But if most of the nitrogen is in ammonium form (ammonium sulfate, for example), nitrogen release will be slower-taking anywhere from 2 weeks to 3 months- but should be more sustained once it starts.

Then there is ammonium nitrate, which consists of half ammonium nitrogen and half nitric nitrogen; it therefore yields some of its nitrogen quickly and some slowly.

PHOSPHORUS-The second secret code on the fertilizer label is phosphorus. It is listed as available phosphorus acid. Unlike nitrogen, phosphorus does not dissolve and move through the soil for the roots to absorb.The soil has to 'give it up' and it does so reluctantly. The soil, mixed with the microscopic film of water releases the phosphorus ions to the soil particles in small amounts. As the root tips grow into contact with the soil, they absorb the phosphorus the soil has released in that area. Usually it is not enough to satisfy the plant so the roots grow into another area to get what they need, and the cycle starts again.The release of phosphorus into the soil particles by the soil can affect the plant's rate of growth.Therefore, the most effective way to use a fertilizer with phosphorus is to concentrate it where the roots can get to it. For established trees and shrubs, use fertilizer sticks, stakes, or tablets.

POTASSIUM- The third secret code on the label is potassium. It can be described in various ways, including available or soluble potash or water soluble potash. Plants remove from the soil more potassium than any other nutrient except nitrogen and calcium.

Potassium exist in soil naturally in several forms. Plants can't use most of natural soil potassium, except about 1%, called exchangeable potassium, which acts an important source for plants.Exchangeable potassium is not soluble until changed by a slow weathering process. However, roots can pick up exchangeable potassium from clay or humus particles. Like phosphorus, potassium is only effective if placed near the roots.

Tomorrow: continuing with those-those-those numbers!How do you choose the one that's best?

A farmer was driving along the road with a load of fertilizer. A little boy, playing in front of his house, saw him and called "What've you got in your truck??"
"Fertilizer", the farmer replied.
"What are you going to do with it?" asked the little boy
"Put it on strawberries," answered the farmer
"You ought to live here," the little boy advised him. "We put sugar and cream on ours."


As always, we would love to hear from you! Please share here; Or find us on Facebook!

1 comment:

Virginia said...

Pretty informative and well researched! Funny photos too. Good job.