Hydrogels which retain moisture around tree roots can aid seedling establishment and growth, and potentially extend the planting season beyond its traditional winter window.  

A trial to test a seaweed-based hydrogel was set up by a team from Scion together with Timberlands and contractors H.A.Fear.  The hydrogel was applied, and the trees planted, using a mechanical ‘M-Planter’ in Tarawera Forest in March 2022. The site was renowned for its dry, difficult establishment conditions.

On this occasion the hydrogel had no significant effect on tree survival, and only a minor positive impact on early growth, perhaps because the weather was unusually wet around planting time.  A second similar trial was planted with the M-Planter in December 2022 in collaboration with Rayonier-Matariki Forests to see whether hydrogel would increase survival over drier summer conditions. Again the trial was compromised by unseasonably wet weather, however, the team learned a lot about the operation of the M-Planter in wet weather and clay soils.

Research on hydrogels will continue because their use is closely aligned with mechanised planting. Extending the planting season is key to increasing planting machine utilisation, thereby improving the overall cost-effectiveness of mechanised operations. 

Collaborators: Timberlands Ltd, Rayonier-Matariki Forests, H.A Fear Ltd