Using Representation Systems Flexibly - Example 5

Arable Farming in the Roman Empire

In the Roman Empire, there was not much fertiliser available in the form of dung for its fields since there were frequently no larger herds of cattle near the farms. The further away the cattle herds were from a farm, the less dung was available for the fields. The less dung there was for fertilising, the more frequently the farmers had to let the corn fields rest.

The following diagram shows the effects of the distance of the cattle herds from the farm, the availability of fertiliser in the form of dung, and the frequency of resting periods when growing corn crops.

Cattle  = distance of the cattle herds from the farm
Dung  = availability of fertiliser in the form of dung
Rest  = frequency of resting periods when growing corn crops

If there was less fertiliser in the form of dung, nitrogen-rich plants were cultivated and used as fertiliser. However, due to the low rainfall frequency in the Roman Empire, this was not always possible: the fewer the rainfalls, the less nitrogen-rich plants could be grown. Nevertheless, intensive irrigation significantly increased the cultivation of nitrogen-rich plants and so decreased the frequency of resting periods for growing corn.

What additions have to be made to the diagram to show these effects correctly?

Cul      = cultivation of nitrogen-rich plants
Dung   = availability of fertiliser in the form of dung
Irrig     = intensity of irrigation
Rain    = rainfall frequency
Rest    = frequency of resting periods when growing corn crops

Which of the following statements is or are correct?

I. Cul is positioned between Dung and Rest and is linked to both by . One points from Dung to Cul, one points from Cul to Rest.

II. Rain and Irrig are each linked to Cul with a Both arrows point to Cul.

Degree of difficulty: hight

Solution