Plant Talk |
CAUTION:The information and recommendations in this article are applicable to Harnett County, NC and may not apply in other areas.
ALL ABOUT FERTILIZERS, 08/15/97
We know that plants need nutrients, and we know that fertilizers supply them. Nowadays, with all the focus on health, most people have a good understanding of their own dietary needs (lots of fruits and vegetables, low fat, low sodium, etc.). Probably not nearly so many understand the nutritional needs of their plants.
Plants need 17 different nutrients, each of which plays a role in plant growth. Thirteen of these are usually present in soil and do not need to be added, except in special cases.
The other four, nitrogen, phosphorous, potassium, and calcium, are normally added by fertilizers. They are commonly abbreviated as N, P, K, and Ca, respectively.
To simplify things a bit, nitrogen promotes leafy growth, phosphorous is important for fruit production, and potassium promotes root growth.
So what does that mean when you go to purchase a bag of 10-10-10? Those three numbers refer to the percentages of nitrogen, phosphorous, and potassium. Thus, a 100 pound bag of 10-10-10 contains 10 pounds of each of those three nutrients.
Calcium, on the other hand, is found in lime. Thus, lime plays a dual role by adding calcium, and also by raising soil pH.
Soil pH is measured on a scale from 0 to 14 and refers to how acid (0-6) or alkaline (8-14) the soil is. Pickle juice, for example, is acidic, while chlorine beach is alkaline. If the pH is wrong for a given plant, then it will not be able to absorb some of those important 17 nutrients.
There are many different fertilizers to suit your specific needs, based on your soil test report. For example, a 15-0-14 contains no phosphorous. What is commonly referred to as soda is a 16-0- 0, containing only nitrogen.
It is also possible to purchase slow release forms of nitrogen. These have the advantage of supplying small amounts of nitrogen gradually over a longer period of time.
Organic nutrient sources, such as bone meal, blood meal, and manures, are no better or worse than the nutrients supplied in 10-10-10. They do have the advantage, however, of adding some organic matter, which is beneficial to soils.
So now let's apply this to what our plants need.
First, they need the proper pH. Secondly, they need the right nutrients in the right amounts at the right time. Timing is critical because different plants have different growth cycles.
Fescue, for example, is a cool season grass. It grows best during the spring and fall. We want to apply fertilizer close to the times that it is actively growing (i.e. mid-September, November, and January), not during the summertime when it tends to go dormant.
Warm season grasses, however, should be fertilized during the late spring and summer when they are actively growing (have you called to request your lawn maintenance calendar?).
I doubt my editor will let me take up the whole page, so you'll have to call for details about other specific plants. By supplying our plants with the proper diet, we help to keep them healthy, and also protect our water supplies from unneeded fertilizer runoff.
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