Growing native trees with machines

Department of Conservation —  31/08/2017

By Susan Streatfield, Partnerships Ranger 

Imagine a machine that could effortlessly sow native seeds straight into the ground, creating within hours what will grow to become a woodland, open forest or wildlife corridor.

Such a machine exists and is heading our way!

The Burford Tree Seeder in action. Photo: Toby Jones.

The Burford Tree Seeder in action. Photo: Toby Jones

Farming with Nature is a new programme within DOC to promote conservation on farms. The first step is the Grow Native project looking at cost effective techniques of integrating native vegetation back into farming systems.

Many months have been spent identifying farms, sites, and species across Otago and Southland to trial direct drilling. An Australian invention was chosen as the best machine in which to trial the direct drilling of New Zealand native seeds.

The Burford Tree Seeder

Built by Rod Burford in South Australia in the late 1980s, the Burford Tree Seeder was a machine of its time.

Its construction coincided with the Decade of Landcare in Australia, which began in 1990 to address widespread land degradation issues such as erosion, salinity, deforestation and vegetation fragmentation. Dozens of landcare groups sprung up across Australia to tackle local environmental problems.

In the late nineties, the Australian Government created the $1.5 billion Natural Heritage Trust.

The country experienced an unprecedented investment into landcare, conservation and the environment and an entire industry grew and flourished, supplying fencing, plants, seeds, advice, research, new technologies and innovations.

The view from behind. Photo: Ian Rayner.

The view from behind. Photo: Ian Rayner

Burford Tree Seeders thrived and were rolled out across Australia to some of the most challenging environments.

Most machines were, and are, still owned by Landcare Groups and one of Australia’s largest environmental organisations ‘Greening Australia’.

Old ways aren’t always best

To fully appreciate the Burford’s value in restoring landscapes, it is important to understand what it, pardon the pun, ‘superseded’.

Native plants have long played a role in combating land degradation, providing shade and shelter for livestock, increasing carbon sequestration, biodiversity and connectivity.

Traditional plant restoration has involved the planting of nursery stock which, although necessary in some areas, is generally expensive and labour intensive.

Planting the old-fashioned way.

Planting the old-fashioned way

When propagating nursery plants, seed is collected, cleaned and stored before being sown into seed trays.

Plants are transplanted and grown for many months in hot/tunnel houses before they are hardened off and distributed to their final destinations.

The ground is deep ripped, sprayed for weeds and the tubestock usually planted by enthusiastic volunteers or land managers. A tree guard to deter browsers and a short prayer completes the process.

Machine on a mission

The Burford Tree Seeder was custom made for the sole purpose of sowing the seeds of native trees and shrubs directly into the ground with the original design barely changing in over 30 years of operation. It has a steel disc for scalping a narrow furrow, a twin seed box for delivering small and large seed types and a press wheel for a final finish. The ground is strip sprayed beforehand – sometimes once, but more often twice, depending on the level of weed competition.

A 25-year old multi-purpose, direct seeded windbreak. Photo: Ian Rayner.

A 25-year old multi-purpose, direct seeded windbreak. Photo: Ian Rayner

The machine is calibrated to distribute around 150–200 grams of mixed seed per kilometre and can seed around 50 linear kilometres a day.

Seed mixes generally contain around 20 different species of trees and shrubs. Once they are sown over the sprayed strips they require little to no maintenance. The cost of direct seeding is around 15% of traditional planting.

Successful direct seeding usually depends on securing adequate quantities of locally sourced seed, good site preparation and site selection (avoiding wet, highly fertile/competitive or steep areas).

A welcome Aussie – New Zealand’s first tree seeder

New Zealand’s first Burford is now crossing the ditch, arriving in time for seeding trials this spring.

A retired practitioner with 25 years of direct seeding experience will be here as a volunteer to help us test drive the machine on New Zealand soil. Sites have been sprayed and fenced where necessary and seed collected from nearby wild populations.

A 15-year old direct seeded paddock which had livestock returned 5 years after seeding. Photo: Sue Streatfield.

A 15-year old direct seeded paddock which had livestock returned 5 years after seeding. Photo: Sue Streatfield

The seeding will be monitored for species survival, densities and growth rates, to determine whether the Aussie Burford really is a cost effective alternative for native plant restoration in New Zealand. If so, it has the potential to revolutionise conservation on farms.

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