Implications for agriculture and intensive farming

Overview

Extra energy cost of producing animal products, one argument in favour of keeping livestock on some farmland and two economic advantages of intensive farming.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   Why does producing a kilogram of beef need far more land than producing a kilogram of wheat?

   Model answer

   Cattle feed at a higher trophic level and about nine-tenths of the energy in their food is lost, so a much larger area of crop must be grown to feed them.

2. 2

   What is meant by the extra energy cost of producing animal products?

   Model answer

   It is the energy lost in the additional transfer from crop to animal, which makes meat, milk and eggs far more expensive in energy terms than plant food.

3. 3

   State one argument for a population eating more plant food and less meat.

   Model answer

   The same area of land can feed many more people if the crop is eaten directly, because one wasteful energy transfer is avoided.

4. 4

   State one argument in favour of keeping livestock on some farmland.

   Model answer

   Much upland and rough grazing cannot grow crops at all, and animals convert grass, which humans cannot digest, into food that they can.

5. 5

   How do fertilisers raise the primary productivity of a crop?

   Model answer

   Fertilisers supply nitrate and other mineral ions that would otherwise limit growth, so the crop fixes and stores more energy per square metre.

6. 6

   Why does confining livestock improve the ratio of production to respiration?

   Model answer

   A confined animal moves very little and is kept warm, so it respires less and converts a greater proportion of its food into new tissue.

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