KEY POINTS:
All New Zealand's agriculture is in the firing line as climate change continues - and the likelihood of increased numbers of "weather bombs" extends the risk beyond farmland, a soil conference has been told.
The Soils and Society 2006 conference was told climate change was impacting directly on the nation's soils.
"Our land-based industries are in the front line because they are so very exposed to the risks and opportunities," Agriculture Minister Jim Anderton told the Rotorua conference in a speech delivered for him by Murray Sherwin, the director-general of the Ministry of Agriculture and Forestry (MAF).
In recent years, "weather bombs" had eroded soil from hillsides. "The 2004 Manawatu slips shocked everyone who saw them. Erosion had changed the profile of affected areas, leaving some with no soil or disturbed soil, and recovery would take many years in those areas.
"Even then there is no certainty about how much can be repaired," Mr Anderton said.
Erosion experts recently told the minister that flooding in the Manawatu and Bay of Plenty had clearly demonstrated how vulnerable New Zealand's hill country was to storm-initiated erosion.
Agricultural policies of the 1980s encouraged vegetation clearance, stocking and fertiliser application on marginal land - things that were not sustainable for marginal land, the experts said. The high returns in pastoral farming meant land prices were high, even for erosion-prone land, but landowners were seldom held responsible for the off-site costs caused by soil erosion.
These included silt building up river beds and causing erosion of river banks, increased flooding, and loss of low-lying productive land.
The conference was told global warming would increase the magnitude of future storms and the nation could expect to sustain further loss of steep hill country soils and off-site damage to property.
Protecting soil must be a national priority to prevent flooding and damage in severe weather.
Greg Carlyon, group manager of planning at the Manawatu-Wanganui regional council, told the conference that after the 2004 "weather bomb" his council introduced an $80 million sustainable land use initiative. "We are challenging some entrenched farming practices, and getting landowners to focus on protecting their land from soil erosion," he said.
An increase in the frequency and severity of the nation's heavy rainfall and flooding would mean more "weather bombs" such as the one that hit the Manawatu-Wanganui region in 2004 and Canterbury this winter, he said.
There are about 6000 farms in the Manawatu-Wanganui region and the regional council estimated that 300,000ha of hill country was at risk of erosion.
The 2004 storm affected 70 per cent of the region and about 200 million tonnes of soil was lost, resulting in an estimated $300 million damage to the regional economy.
"Soil is one of New Zealand's key resources - and it is essential that we protect this for future generations," he said.
- NZPA
