The Soil Conservation and Rivers Control Act
There had been some erosion surveys in the 1930s, along with growing concerns about erosion. In September 1941 the Soil Conservation and Rivers Control Act was passed, the Soil Conservation and Rivers Control Council was set up.
The aims of the council were to:
- promote soil conservation
- prevent and reduce erosion
- prevent flood damage
- use land in a way that would achieve these aims.
The act set up catchment districts, and the Soil Conservation and Rivers Control Council established catchment boards (with elected and non-elected members). The main purpose of the boards was to minimise and prevent damage by floods and erosion.
By 1945, 11 boards had been formed, and by 1967 there were another six similar commissions or authorities. The entire New Zealand landscape was covered.
For the greater good
Spreading fertiliser, which encouraged pasture growth, was crucial to the success of soil conservation efforts on steep land. However, at first, soil erosion prevention was done for economic rather than environmental reasons.
Single subsidies for farmers
In 1946, the Soil Conservation and Rivers Control Council devised a subsidy system to help farmers conserve the soil.
Up to 1956, farmers were assisted with single methods such as retirement fencing, which fenced off areas not suitable for grazing. Windbreaks, debris dams, pasture furrows and tree-planting in gullies were also subsidised.
Catchment boards soon realised that a whole-farm approach was needed when several methods were in use. The farmer had to adopt a mutually agreed ‘farm plan’ over a set period, normally five years.
A farm plan was based on a land capability survey. This divided farmland into eight classes – four arable (crop-growing) and four non-arable. The surveys were first done in 1952.
Engineers vs conservators
The Soil Conservation and Rivers Control Act 1941 linked erosion with flooding. Catchment board staff were river engineers and soil conservators, who often disagreed on how to control flooding.
Some engineers believed that works such as stop banks and stone gabions (rocks inside wire mesh) would control flooding, whereas soil conservators considered that the upper parts of a river catchment should be the focus. Eventually both viewpoints were included in flood control programmes.
Catchment control schemes
The first major catchment or river control scheme was begun by the South Canterbury Catchment Board, and approved by the Soil Council in 1951 for the Ōpihi catchment.
In 1973 conservationist Lance McCaskill noted:
[T]here has been an outstanding change in the main catchment, rabbits have disappeared, vegetation provides almost continuous cover, soil erosion is no longer a serious problem, wells and springs run throughout the year, the smaller streams are under control, and the hydraulic efficiency of the main river channels is steadily improving. 1
Other catchments then started similar programmes to control erosion and rivers.