Good turnout at slip field day

By Allan Barber allen@barberstrategic.co.nz

More than 60 farmers and landowners gathered at the Ahuroa Hall for a wellorganised series of presentations to provide advice and support for remediating land affected by recent weather events, particularly the Anniversary Weekend storms.

Beef + Lamb NZ’s extension manager for the northern North Island, Katrina Stead, organised the programme, which was designed to advise on planning for shortterm recovery and long-term resilience.

On the panel of five speakers was John Ballinger, from Northland Regional Council, talking about the adverse effects of different soil types and sediment flows; Duncan Kervall, a soil scientist from Kaipara Moana Remediation (KMR), who spoke about planting the right sort of trees to minimise erosion and withstand extreme weather events; Mark Forsyth, NZ Forest Service adviser, on the nuts and bolts of the Emissions Trading Scheme; and soil experts Dr Ants Roberts, from Ravensdown, and Murray Lane, from Ballance. Auckland Council was not represented at the meeting, apart from Rodney Local Board member Tim Holdgate, but Stead conceded she and her colleagues who put the event together had not specifically invited anyone from the organisation, though CCO Watercare was aware of it. The first two speakers highlighted the challenges of keeping soil on the hills and slowing the sediment train with sandstone and mudstone shifting in different directions on Kaipara’s highly erodible land mass of 135,000 hectares, of which 45% is pasture. There are 8000km of waterways and 4000 properties all feeding into the Kaipara Harbour. Thousands of tonnes of sediment finds its way into the harbour annually, which has enormous implications for its health and fish populations. The best ways to manage these two issues are judicious tree planting, abiding by the mantra ‘right tree, right place, right purpose’, and the creation of wetlands. Several trials are under way in Northland to find the ideal combination of tree species and space between plantings for highly erodible soils, which are also found across the Rodney district. No one tree can do all the jobs required, but 95% of Northland plantings are radiata which experience, since Cyclone Bola in 1988, has proven to have an extremely unstable root system. Poplars have been one of the alternatives which have achieved landslip damage reduction with a relatively small loss of pasture, but unfortunately the clone originally selected is unsuitable for steeper areas or riparian planting because of a small root system and heavy overhanging branches. As a result, two major government incentivised tree types have caused more landscape damage, instead of solving the problem they were intended to, at least on highly vulnerable land. KMR provides grants and works with landowners to develop a sediment reduction plan for each farm. It will pay half the costs with the other half being contributed, either in cash or in kind, by the landowner. The organisation, which is funded by central and local government, is currently working with 500 farmers and already has 400 sediment reduction plans in place. It is working closely in tandem with Northland and Auckland councils, Fonterra and Beef + Lamb NZ to ensure duplication is avoided.

The last two speakers discussed the topic of revegetation, the effect of slips on pasture productivity, the use of technology to map the farm before and after major storms to assist decision-making, and sowing seed by heli-cropping, which leaves the topsoil undisturbed.

Streamland Suffolk stud co-owner Sue Meszaros was particularly impressed by the practical nature of these last two presentations on soil recovery and revegetation, while also praising the work of the Rural Support Trust and Forest Bridge Trust in helping with fencing and slash clearance.

Ahuroa farmer Glen Ashton finishes cattle on a combined total of 344 hectares on which he has also planted 250,000 trees. His farms suffered substantial damage to fences, tracks and crossings from the landslips and he is focusing on fixing the most critical issues first.

He thought the field day was informative, but considered the advice on tree planting ignored the fact that water must find its way down the hill and eventually into the harbour, so planting to block creeks only causes problems for properties further uphill. On his farm, he had at least one slump where a whole hillside had shifted two metres sideways. He made the point these weather events and their damage to the landscape were not a new phenomenon. His positive attitude was typical of the field day attendees who were interested in what the presenters had to say and keen to get on with the job of recovery.