Queensland’s Industrial Hemp Variety Trials (IHVT) site was funded and overseen by AgriFutures Australia, with research by the University of Sydney. From December 2022, trials were undertaken at Stanthorpe using hemp seed varieties originating from Australia, Canada, France and Poland. The varieties were selected based on agronomic parameters from Australia and similar regions internationally including plant height at maturity, dry matter production, grain yield and quality.
Stanthorpe grazier and Australian country music performer James Blundell said he was pleasantly surprised by the results of the trial crop on his Granite Belt property. “We put an old plough into a paddock that had never been cultivated and I had no idea how the plant would respond. I knew it to be a resilient plant but I didn't realise how hardy it really was”.
James Blundell plans to grow a commercial hemp crop on his Granite Belt farm by 2028.
The trial site followed fully organic management practices in planting nine industrial hemp varieties at two times of sowing (6 and 22 December, 2022). Trial plots were 6m by 1.575m with seven planting rows at 22.5cm spacing. They were planted using a 7-row tine planter with spring rollers. The target plant density was 150 plants/m2 and the seed sowing rate was calculated according to germination percentage and seed size which varied between varieties.
Associate Professor Guy Roth, who led the project, said, “We cultivated the trials in a very similar way to most crops and used conventional cropping machinery and conventional practices”. Both Professor Roth and agronomist John Muir, who managed the trial, believe growing hemp along with traditional crops is key to the success of the burgeoning industry. “If you are growing summer crops now, like cotton, then you can grow hemp”.
Drip irrigation tape was used to ensure water was not a growth-limiting factor. AgriFutures Australia estimates industrial hemp requires two-to-six megalitres of water per hectare, lower than cotton’s average irrigation requirement of between six and seven megalitres.
Crops were sown at a depth of 2cm. High plant density is desirable for smothering weeds, which is important given there are limited registered herbicides for industrial hemp. It is also important for promoting competition between plants to encourage them to grow as single stems with a single flower head, the ideal configuration for machine harvesting.
Fertiliser was applied based on the recommendations of a local agronomist, following soil tests indicating the trial site was low in Nitrogen (N), Phosphorus (P) and Calcium (C). Calcium and other nutrients were applied via fertigation at two times during the season, while in total the crop received fertiliser of 206kg/ha of N, 101kg/ha of P, and 189kg/ha of Potassium (K). As an organic site, no synthetic insecticides or herbicides were applied.
Germination and seedling vigour differed between varieties, resulting in variable establishment and plant density of some varieties despite adjusting the sowing rate. The plants were measured for establishment counts, plant counts at harvest, plant height, total dry matter production, grain yield, 1,000-grain weight, grain bulk density, grain protein content and grain oil content.
Grain yield ranged from 0.34 t/ha for Katani to 0.79 t/ha for Orion-33, but did not vary significantly between varieties, nor did the harvest index. However, there was significant difference by variety in total dry biomass yield which ranged from 2,220kg/ha to 7,070kg/ha, thousand grain weight from 5.25g to 11.68g, grain bulk density of 29.95-43.02kg/hL, protein content 19.5-26.9% and oil content 11.15-26.58%.
Four varieties, namely CFX-2, CRS-1, Katani and Ruby, displayed dioecious sex expression with more female plants than male plants. By contrast, Bialobrzeskie-08, Fedora-17, Fibror-79, Henola-09 and Orion-33 displayed predominantly monoecious habit with a majority of hermaphrodite plants. With the exception of Ruby (dioecious), the monoecious varieties had a longer season length than the dioecious varieties trialled, which was correlated with a taller plant height and greater biomass.
The best performing variety across a range of grain production and quality parameters in 2022-23 was Fedora-17. Other than Ruby (dioecious), the monoecious varieties outperformed the dioecious varieties for both biomass production and grain yield. However, these results are based on one season of data only. Given every season is different, growers should wait for further results from different seasons with a range of sowing dates before deciding on variety preferences for this region. The detailed trial reports are published here.