Massey University historian James Watson was awarded an "Ig-Nobel" in October for his investigation of why Hawera farmer Richard Buckley's trousers exploded in August 1931.

Before you laugh, the study wasn't obscure, nor was it lightweight - more on that in a moment.

And the Ig-Nobels themselves are not a complete mickey-take: the annual awards, say organisers, are given out to those whose work first makes you laugh, then makes you think.

Dr Watson, 53, the head of the university's department of history, philosophy and politics, was reportedly a bit embarrassed when he heard of his award (other prizes went to the inventors of an alarm clock that rings then runs away so you have to get up, and artificial testicles for neutered dogs).

But he went to the ceremony at Harvard University and changed his mind, having met "many amazing and very, very clever people".

The paper is called The Significance of Mr Richard Buckley's Exploding Trousers: Reflections on an Aspect of Technological Change in New Zealand Dairy Farming, published in North Dakota State University's Agricultural History journal.

It outlines how farmers of the era raced to embrace sodium chlorate as a ragwort killer.

Unfortunately, when mixed with the cotton or wool fibres of a farmer's work clothes, sodium chlorate - a white crystal also known as chloric acid and sodium salt - formed compounds that detonated at the first sign of a spark or knock. Washing was no protection.

Mr Buckley's trousers were drying in front of the fire, when, according to the Hawera Star, "they exploded with a loud report".

"Although partially stunned by the force of the explosion, he had sufficient presence of mind to seize the garments and hurl them from the house, where they smouldered on the lawn with a series of minor detonations".

Mr Buckley was lucky, says Dr Watson: one farm worker went in to his baby's room one day after work and, in order to better see the child, struck a match. Boom! He died of his injuries.

Dr Watson's paper adds: "One individual was shocked to observe a newly hung-out load of washing burst into flame on the clothes-line. Numerous farmers and farm workers discovered for the first time that smoking could be hazardous to their health as items of their clothing lit up when they did. In a New Zealand version of Blazing Saddles, one farmer found that the seat of his pants was starting to smoulder as he was riding his horse."

Now this is all quite funny, in a tragic way, and fascinating. But what's the value of something apparently so obscure?

You need to look at the bigger picture, says Dr Watson - and that bigger picture is an absorbing insight into New Zealand's rural history. In the 1930s, dairying was expanding rapidly, reducing the control of the yellow-flowered ragwort by sheep (cows don't eat it), and large areas of cleared land were becoming weed-infested.

In addition, farmers tended to seek help from the state, and the state was at that time all for sodium chlorate.

Farmers were also facing labour shortages, with people chasing higher wages and better job choice in the cities; socially, there was less approval for children and married women to labour on farms.

But most importantly, suggests Dr Watson, farmers wanted to be as independent - read, employee-free - as possible. A weedkiller as potent as sodium chlorate promised a one-stop solution.

"The adoption of technology, in this case sodium chlorate, has been influenced by social and cultural values as well as economic ones," says Dr Watson.

* These days, sodium chlorate is used as a soil steriliser for agricultural purposes, in match production, and leather tanning and finishing.