Ten years ago, a sprinkler playing on a lawn or garden indicated that the area was being watered.
Today, the same sight might denote that the lawn or garden is receiving fertilizer in the water—two operations combined into one, thanks to the development of soluble fertilizers.
Soluble Fertilizers
Soluble fertilizers do not differ much from other complete fertilizers that have long been popular with gardeners.
As the name implies, soluble fertilizers dissolve readily in water.
Most common garden fertilizers are readily soluble to the extent of about 75% percent of their weight.
The insoluble or very slowly soluble residues usually require decomposition in the soil and other soil processes to dissolve them.
However, the soluble fertilizers generally possess higher guaranteed analyses (guaranteed percentages of nitrogen, phosphate, and potash) than the usual garden fertilizers.
The cost of a fertilizer per pound is not a reliable basis for judging its plant food value.
Likewise, the guaranteed amounts of nitrogen, phosphate, and potash alone are not adequate for evaluating a fertilizer.
High Analysis Soluble Fertilizers
Some “high analysis” soluble fertilizers contain only the following:
- Nitrogen
- Phosphate
- Potash
Others contain those nutrients plus the following:
- Calcium
- Magnesium
- Sulfur
- Iron
- Manganese
- Boron
- Copper
- Zinc
- Molybdenum
The latter are essential nutrients of which one or more are lacking in many soils.
Low Analysis Soluble Fertilizers
“Low analysis” fertilizers permit the manufacturer more opportunity to incorporate amounts of these various essential mineral nutrients that will prevent the occurrence of deficiencies in most crops and soils.
A fertilizer manufacturer may prepare a soluble and relatively insoluble fertilizer and make each one an excellent product, supplying a wide assortment of plant nutrients in safe, effective amounts.
In contrast, either type of fertilizer may be formulated so that it may not adequately supplement the nutrient supply of some soils.
Fertilize With Care
All plants need at least 16 different elements for their normal growth and development.
Of these, 13 must be supplied by the mineral composition of the soil or by fertilizers applied w it.
Three nutrients, the supply of which does not depend on the composition of the soil or fertilizer, are the most important in terms of their content in a plant.
The carbon obtained from air and the hydrogen and oxygen supplied by water comprise 95% percent of a plant’s dry weight.
On the same basis of comparison, the mineral content of a fresh or growing plant is only about 0.5 to 1.0% percent.
Fertilizer nutrients represent only a minor part of the weight of a plant.
The purpose of this comparison is to emphasize the fact that it takes much more than fertilizer to produce plants.
Fertilizers are, therefore, cultural aids in the growth of plants in most of our soils.
Fertilizers stimulate plant growth if used properly. However, if misused, they may drastically stunt growth.
For home gardeners, soluble fertilizers have some important advantages.
Soluble Fertilizer Advantages
When dissolved in water, soluble fertilizers are easily distributed evenly over a garden or lawn area.
Moreover, when they are dissolved at recommended rates, these fertilizers are exceptionally safe to use.
They may be applied over foliage and over the soil, thus getting some additional benefit from foliar absorption.
Since the homeowner usually has an abundant supply of water available, soluble fertilizers permit him to water and fertilize in one operation, thereby ensuring a rapid response from the nutrients added.
Application Methods
Various kinds of equipment are available to home gardeners for applying soluble fertilizer.
The common sprinkler can be the most convenient device where small areas are to be fertilized.
An inexpensive siphon-type dispenser may be used where only a few hundred square feet are to be fertilized.
For lawns and large garden areas, one needs either equipment that can be used with a perforated hose or some other ‘large sprinkling device.
For example, there are now inexpensive gadgets that can be attached between the faucet and the hose, which will dissolve and proportion soluble fertilizers into the hose line.
Fertilizing Rates
Liquid fertilizers are used most effectively as dilute solutions that serve as a combined watering and fertilization.
Because of this, it is recommended that no more than the following amounts of the various popular grades of soluble fertilizers should be dissolved in every 10 gallons of water used:
For 5 ounces:
- 12-12-12
- 13-13-13
- 13-26-13
For 4 ounces:
- 15-15-15
- 15-30-15
- 16-16-16
For 3 ounces:
- 18-18-18
- 20-20-20
- 23-21-17
Ten gallons of liquid fertilizer prepared from any of the above grades of soluble fertilizers can cover at least 40 square feet of the ground.
Two to four applications at these rates per season will supply sufficient plant foods for most garden crops and lawns.