Have you ever broken down a rule of thumb?


On the Friday 14 August several BCG staff and three local growers attended a rule of thumb workshop facilitated by Jeanette Long. A rule of thumb can be defined as a practical principle that comes from wisdom or experience and is usually not valid.

Rules of thumb are used extensively throughout agriculture. These rule of thumbs are used because of the complexity of situations and an inability to gather all the data necessary to work out the expected result of every action.

When a decision is made, it is either based on intuition or analysis of the situation. Intuition is a combination of experiences, goals, gender, personality, assumptions and historical perspectives. Intuition is used because of the intricacy of the circumstance and an inability to gather all the information necessary to gain a result.

To unpack a rule of thumb we need to analyse the:

·         origin

·         experience

·         research

·         possible blind spots

·         and evolution of the rule.

The focus for the day was rule of thumbs used in plant nutrition.  The rules which were focused on included that canola always needed S, faba beans put the most N back into the paddock, topdress if there is a greater than 5mm rain forecast and sowing is to be finished by 15 May in the Mallee.

The workshop was a success for all participants. The group found it thought-provoking to dissect these commonly used rules as it gave a deeper understanding of what analysis or intuition is behind each of them.

What was decided as a group, was that often the origin of the rule of thumb was unknown, and in one case it was perceived that the rule of thumb to be incorrect as there was conflicting evidence.

In general, individuals are more likely to adopt rules of thumb because they are easy and quick to use, but we do still need to analyse the rule of thumb for credibility, bias, reputation and possible blind spots. 

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