Anecdotal evidence showing crops grown post hemp could yield more was confirmed when Nick Mills opened up his Longford mixed-crop property for a hemp field day on Thursday.
While sharing his wins and losses with the crop over the past five years, Mr Mills agreed that crops sown after he had harvested hemp had higher yields.
“We’ve had successful crops post hemp, such as beans,” Mr Mills said.
Tasmanian Institute of Agriculture horticultural researcher Dr Mark Boersma has been working with industrial hemp grower Ecofibre to measure hemp yields.
Both Dr Boersma and Ecofibre managing director Phil Warner spoke at the field day, with Mr Warner commenting that mixed-crop growers had noticed “higher yields after hemp”.
“We want to do some research into rotational cropping with poppies to increase the alkaloid content,” Mr Warner said.
This season’s 42-hectare hemp crop at the 2500-hectare Longford property was planted in late November after an oat crop failed due to weather.
The oat crop came after potatoes, which were harvested in May.
“We had a change of crop and decided to cut the oats for silage and then direct drill in hemp,” Mr Mills said.
“It’s a good crop for rotation because you start growing in late spring and you’ve got it off by the middle of March, so it won’t affect autumn crops,” he said.
This is the fifth year Mr Mills has grown hemp at his Longford property, alternating with potatoes, poppies, grass seed, clover and cereal crops.
“It’s a good short summer crop and it seems to fit in nicely,” Mr Mills said.
“Each year we’re learning a lot more about the crop. We’ve got a lot to learn about nutrition and fertiliser applications.
“Last year was the first year we felt confident. In our first year harvesting was a challenge,” he said.
Grown in a sandy soil like his Longford property, Mr Mills said he used between three and four megalitres of water for hemp, but water needs depended on individual soil profiles.
The crop was treated with seaweed fertiliser, herbicide and nitrogen between November and February, which Mr Mills agreed was costly, but not as much as cleaning.
“The most expensive part [of hemp harvest] is cleaning and drying. We harvest the crop when the stems are green, because the stalks get tough, but then we have to get the moisture down from around 18 per cent to 12.5 per cent,” he said.
Drying costs $170 per hectare for and $260 for cleaning.
“That’s a significant part of the crop,” he said.