Growing Food: A Guide to Food Production

Chlorine, Silicon and Aluminium are also taken up by plants but do not appear to be

essential for plant growth.

1D. FERTILISER

Anything which is added to the soil to increase the amount of plant nutrient (or plant

“food”) can be called a fertiliser, though the word is normally applied to inorganic

(synthetic) chemicals which invariably have to be paid for in cash, as opposed to

organic (non-synthetic) fertilisers—the manures, composts and so on which are

normally produced by food producers themselves on their own holdings.

Chemical fertilisers provide the basic plant nutrients, mainly nitrogen (N),

phosphorus (P) and potassium (K), either individually, as straight fertiliser, or more

commonly as compound or multi nutrient fertiliser.

Organic fertilisers also supply these nutrients, but in much lower concentrations.

The actual amount of the nutrients contained in compound fertilisers is often

expressed as:

• Nitrogen, as %N,


• Phosphorus, as P 2 O 5 (phosphorus pentoxide, often called phosphate, sometimes
  incorrectly called phosphoric acid), and


• Potassium, as K 2 O (often called potash).

Barley OF THE MAIN FOOD CROPS

There are 3 main kinds of fertilisers, which are aggregated in various proportions by the

suppliers to form the various compound fertilisers, some of which include other

elements also, particularly Magnesium (MgSO 4 ).

Nitrogen is supplied either as nitrate (NO 3 ) or ammonium (NH 4 ), or in a combination.

Examples: ammonium nitrate (NH 4 NO 3 )—the most widely used—nitrate of soda,

sulphate of ammonia, urea, ammonium phosphate, potash nitrate etc.

They are sometimes applied in liquid form—ammonium nitrate/urea and other

mixtures are used.

Anhydrous ammonia is sometimes applied as a pressurised liquid that gasifies when

injected into the soil.

These are either fast acting (water soluble) or slow acting (water insoluble).

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1 kg lime/ha), or 3 kg/ha Copper oxychloride.

Foliar: 0.1% Copper sulphate solution (1 kg dissolved in 1000 litres of water/ha with

Sodium
Although this element is very rarely deficient, agricultural salt (NaCl) is sometimes
applied to soils, to increase yields of carrots, sugar/fodder beet and mangels. This is
done two or three weeks before planting, but great care should be taken with salt as
it can stunt or even kill plants; the practice is not very often recommended.

1. Nitrogenous Fertilisers


2. Phosphatic Fertilisers

GROWING FOOD – THE FOOD PRODUCTION HANDBOOK