Growing Food: A Guide to Food Production

some tolerance of waterlogging. Rice has a hollow stem so that oxygen can reach

In general, arable and root crops need a fairly low water table to encourage their
roots to develop fully, while grasses and cereals can tolerate a much higher water table.

Soil Improvement—What can be done with poor, infertile soils?
There is virtually no soil in the world that is not able to produce some form of healthy
food crop if it is properly understood and cared for. Food growers should always try to
grow the most suitable crops available, and the best available variety of that crop, while
at the same time working towards maintaining or improving the fertility of the soil they
cultivate.

Possible cures—some examples:

• acid soils can be cured with lime;


• alkaline soils can be cured with organic, basic fertilisers;


• saline soils can be cured with drainage and an adequate supply of rainwater and/or
  irrigation. Gypsum (Calcium Sulphate) may help the recovery of saline soils. In
  theory, several years of fallow can also cure salinity, though this is rarely
  practicable;


• waterlogged soils can be cured with subsoil cultivations or a good drainage system;


• soils which are deficient in the major elements can be cured with organic or
  inorganic fertilisers, and/or leguminous crops, and grazing animals;


• trace
  missing elements, either to the soil or crop, or by correcting other soil properties
  such as the pH (1Cc, pages 20–23);


• soils with trace element toxicities can normally be cured by correcting the
  imbalance in the soil of other, related nutrients.

Unfortunately most of these techniques tend to be rather expensive, and also the
materials needed and the skills to use them are very often not available. However it is
often possible to provide at least some of the resources needed to improve the soil’s
productivity, and the list above is included to demonstrate that all soils are dynamic and
can be encouraged to grow food if the resources are available.
Food producers can make use of different kinds of plant and vegetable parts to
improve their soil by converting them into organic matter, in compost heaps etc.

Organic Matter
This plays a vital role in the physical properties of soils. It consists of two components:

• undecomposed organic matter—fragments of plants and animal remains, and


• decomposed and partially decomposed organic matter, or humus—dark coloured

organisms; it can persist in the soil for decades.

These two constituents have quite different physical properties. For example,

material, which looks and feels like soil. It is derived from the more resilient

undecomposed organic matter that is broken down, very slowly, by soil micro-

12 TONY WINCH

soils deficient in minor (“ ”) elements can be cured either by adding those

undecomposed organic matter in the form of leaves, straw, manure etc. tends to keep

waterlogged roots down the interior of the stem. See also 1Ad. “The Root System”.