Using a tractor that is one of a kind in Australia, the farmers mowed about 50 hectares of hemp crop that was ready for harvest.

Bob Doyle, a pioneer of the hemp growing industry in the Lower Hunter, said the hemp stalk would be cut into 600mm billets and sent for processing.

He said the early-sewn crops, planted in October, had yielded about 10 tonnes of stalk per hectare, while the crops sewn later had produced about six tonnes per hectare.

Hemp can be sold for use in the construction industry as a replacement for bricks and concrete because of its high insulation properties and strength.

Mr Doyle and the group of Hunter farmers have bought the old Maxwell’s Timber Mill and plan to set up a processing plant at the site.

He had previously told the Mercury that the hemp industry, which became legal in NSW in 2008, was an untapped financial opportunity for Hunter farmers because the demand for hemp outweighed the number of suppliers.

Hemp and marijuana are both types of cannabis, but hemp has a different chemical make-up from its illegal cousin.

It has low THC levels, so it cannot be used for a high like marijuana.