CRIMINALS MAY RUE POT FROM THIS PLOT

Just like any other greenfingered cannabis grower, scientist Dion
Sheppard fastidiously removes the male plants from his plot.

But while illegal growers cull the crop in order to boost the potency
of their pot, Mr Sheppard's reasons are prosaic.

The 24-year-old is completing his master's thesis exploring the
question of "origin determination," in this case discovering whether
cannabis plants grown in the same soil share the same elements.

Police may be able to use his discovery - that there are identifiable
characteristics in cannabis cultivated in Northland soil compared with
Blockhouse Bay soil - when prosecuting growers.

"For example, when two separate cannabis samples are recovered by the
police, it may be possible to determine if they were originally grown
in the same location," said Mr Sheppard. "This may lead to further
charges for the offender."

Needless to say, the technician at the Institute of Environmental
Science and Research's forensic science service centre laboratory is
not an offender. Mr Sheppard has a licence to grow pot, cultivating a
baker's dozen of mature females - enough to charge him with
cultivation with intent to supply.

Like a criminal, he weeds out the male plants to replicate "a
real-life situation" and also to produce more plant material, caused
by the plant's failure to pollinate.

But Mr Sheppard's crop would have been a commercial failure. So as not
to contaminate his research, he did not use fertiliser or lights for
his indoor crop.

The result was spindly, thin plants, that nevertheless provided a
harvest containing the THC component that causes users to get high.

After the plants reached maturity, he harvested, dried and subjected
the material to a nitric acid test to produce a liquid for analysis.

This provided a list of elements such as magnesium, potassium and
sodium which he used to determine the soil type.

While his research could not yet be used in a court of law, he said,
similar origin determination studies had resulted in prosecutions in
the United States.

For example, the prized Iowa potato possesses unique elements that
allow authorities to prosecute sellers of bogus spuds.