Plainsman1963

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.
3-14-06 | Manawatustandard

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.