HEMP HARVESTED TO CHECK POLLUTION

A crop of hemp is being harvested in Feilding to check the absorption
rates of known river pollutants - phosphorus and nitrogen.

There are three plots of hemp near Feilding's sewage treatment plant,
which treats waste before it reaches the Oroua River.

The crop is looking promising, and one plot, planted in November, has
reached 2.5m in height.

The plants are sub-irrigated with tertiary treated waste from the
sewage plant. This means the waste is treated several times before
being put on paddocks.

Although the hemp looks like marijuana, it has only a 100th of the
hallucinogenic THC of the illegal drug.

The cultivar is grown under licence and managed by retired Massey
University lecturer Mike Nichols.

Masters student Randall Gibson, who is doing a thesis on hemp
cultivation, is taking samples from the plot planted in November to
gauge nitrogen and phosphorous content. Hemp is known to be a good
absorber of these pollutants.

Mr Gibson is unsure what will become of the crop after it is
harvested, as hemp production is in its infancy.

"Hemp has been a prohibited crop, so we still don't know much about
it. Like, what variety to grow, when to sow it, when to harvest it
and where to plant it. There is plenty of potential there, but we're
absolutely ignorant about it."

Huge amounts of nitrogen and phosphorous were found in a hemp crop
harvested recently in Canterbury - 400kg of nitrogen and 100kg of
phosphorous per hectare.

Although grass could do a similar job, over a longer period of time,
the use of human waste to irrigate crops - which fed animals - raised
ethical issues. This was one reason why hemp was chosen, Mr Nichols said.

It was also chosen because it was fast-growing.