Understanding Garden Fertilizers : Gardening Fertilizers

Garden Fertilizers / Gardening Fertilizers


The dividing line between garden manures and garden fertilizers is very finely drawn but as far as the practical gardener is concerned, manures are widely regarded as being of organic origin, fertilizers of chemical origin. The fact that one could be the extract of the other is neither here nor there.

There are fashions in gardening fertilizers and in their distribution and availability. Since gardening, or horticulture, became big business, return on capital is often more persuasive than availability.

Sadly, perhaps, this means that two-thirds of all the wisdom written about the use and application of chemical or artificial fertilisers is no longer relevant, for the simple reason that many of the compounds are no longer readily available. For example, the so-called straight fertilisers such as sulphate of ammonia are not easy to find. The main straights are nitrogenous fertilisers such as sulphate of ammonia and nitrate of soda, phosphates in the form of super phosphate and potash in the form of sulphate of potash.

Their place has now been taken by granular compounds in various ratios either in equal parts as in the case of Growmore with its seven parts of each of the main fertilisers, or biased to suit a particular crop, say an extra dollop of potash in the case of a potash-loving crop such as potatoes.

More and more slow-release fertilisers are on the market and these give up their constituents over a long period and instead of being almost instantly available, as in the case of sulphate of ammonia, the nitrogen may be in several forms. In fact, some firms claim quick release, mid-term release and late release in one compound alone. Unfortunately experience has shown that there is a certain variability in this depending on temperature and the amount of moisture in the soil, and a slow-release fertiliser applied in the early part of the season with the intention of the nutrients being released throughout the growing period of the crop, may run out of steam during the first two or three weeks. This results in the crop getting an excess of nitrogen and then nothing.

Every fertiliser manufacturer has his own specific formulae for various crops and the gardener with limited experience is advised to use them specifically in the way that they are recommended on the pack and, as experience is gained, to supplement them with various straight fertilisers to suit the demands of a particular crop in a particular season under particular circumstances. There is very little danger of over-application, for the simple reason that unless you have a very deep purse you could not afford to do it.

Many old books containing diagrams of which fertilisers to mix together and which fertilisers should not be mixed have gone by the board as few of them are available. The main thing to remember is that none of the fertilisers should come into contact with lime. The reason for this is simply a chemical one. When most fertilisers come into contact with lime a chemical change takes place and some of the elements are released either into the air or into the soil before the plants can make use of them. So if you apply fertiliser to the surface don’t immediately apply lime. This goes for organic manures as well and a good rule is to separate applications of manure and fertiliser from lime either by space or lapse of time.

Reading the Packet

fertilizer bonemeal

It is important to read and understand the analysis of modern compound fertilisers which by law is required to be printed on the packet. These fertilisers have been made up by chemists and experts in plant nutrition to suit the needs of a particular plant or group of plants.

Bearing in mind what has been said about the need for nitrogen for leafy plants, read off the percentages of nitrogen, phosphates (sometimes expressed as phosphoric acid) and soluble potash.

The way in which the analysis is printed varies slightly from company to company and indeed from country to country, but basically the message is the same.

As an illustration, a well-known grass fertiliser will be described as 36% nitrogen, 6% potash and 8% phosphoric acid.  A fertiliser suitable for pot plants would be: 16% nitrogen (8% nitric, 8% ammonic compound), 21% available phosphoric acid and 27% water soluble potash.

The recommended rate of dilution must also be studied, especially if they have to be mixed with water before application. The higher the nitrogen in the analysis, for example, the greater dilution. This need not lead to worry or confusion just so long as the recommendations are carried out. Gardening fertilizers of the powder and granule kind will take longer to act if left to be washed in by normal rainfall which may fall infrequently. Their action can be speeded up if they are washed in artificially using a hose pipe or watering can.

Foliar Fertilizers – Foliar Feeding

Refined fertilizer elements plus minute traces of essential chemicals are available in highly concentrated solutions and often only a few drops per gallon are required. These are particularly useful during periods of drought when, due to lack of moisture in the soil, it is not possible for the plant to take in plant foods in solution by the roots.

Foliar fertilizers are feeds which are absorbed by the green parts of the plant only at the rate that the plant requires them. I must admit that in many instances this is an act of faith because without complete chemical analysis of the leaf it is mainly guess work. However, if this method of feeding is used then it is better done in the evening and, in particular, when the foliage is damp with dew.

07. August 2010 by Dave Pinkney
Categories: Manures and Fertilisers | Tags: | Comments Off on Understanding Garden Fertilizers : Gardening Fertilizers


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