Work on poplars and willows
New Zealand Tree Grower May 2006.
In the past four years there has been a concerted effort to compile information on growing poplars and willows on farms, based largely on farmer experience and on-farm research. There are millions of poplars growing throughout New Zealand, mainly for soil conservation and to provide shelter and shade for livestock. This is a huge asset that needs to be quantified to provide landowners with best-practice guidelines for managing them safely.
Research on particular aspects of these tree species is being funded by the Foundation for Research, Science and Technology, enabling HortResearch scientists Ian McIvor and Sarah Hurst, and AgResearch scientist Grant Douglas to study tree growth in pasture.
Aspects investigated include tree pasture interactions, the effect of spaced trees on the surrounding micro-environment, tree water use, and more recently the root distribution of young poplars on hillsides and how this varies with tree spacing.
Two successive three year farmer-led projects looking at poplars and willows on farms have been funded by MAF’s Sustainable Farming Fund. This is under the leadership of Wairarapa hill country farmer Peter Gawith and involving regional council staff in the lower North Island and in Otago, and researchers Tom Barry and Peter Kemp from Massey University. Those already mentioned above, farm consultants in Manawatu and Wairarapa, and independent contractors Barrie Wills based in Alexandra and Deric Charlton in Palmerston North are also involved.
The first of these projects focused on using these trees as supplementary fodder and ran from 2001 to 2004, whereas the second project has concentrated on tree management in existing and novel tree pasture systems, to develop best practice guidelines on their use.
A third Sustainable Farming Fund project was undertaken on a commercial dairy farm in Wairarapa from 2001 to 2004, involving HortResearch, AgResearch, Fonterra, and Regional Council personnel, which looked at using coppiced poplars and willows for dairy farm effluent absorption. A sequel to this project is included in the current ‘Poplar-willow management for multiple uses’ project, where the effluent management concept is being evaluated on a farm in Otago.