The effectiveness of pasture furrows, graded banks, terraces, grassed waterways, and flood control dams in controlling soil and water movement on arable lands encouraged the Council to provide machinery and technical services, and to plan and install these conservation aids on a demonstration basis where farmers needed them. This work is now carried on by four units controlled by the Department of Agriculture.

In many of the large catchments on hill and high country where erosion and run-off were most severe, there remained a further problem – that of phosphate deficiency. As long as topdressing had to be done by hand alone, no major development was possible to restore fertility, improve protective pasture cover, and increase production on millions of acres of hill country. It was against this background that proposals were drawn up, financed by the Soil Conservation Council, for the original aerial topdressing trials and large-scale demonstrations in 1947–49. These captured the imagination and enterprise both of farmers and of operators to the extent that over 5 million tons of phosphate have been distributed by aircraft, largely on hill country. This has been supported by oversowing of grasses and clovers, by weed spraying, fence dropping, and rabbit poisoning. Unfortunately this improvement of pasture, which lays the foundations of a conservation farming system, has forged ahead of the capacity of catchment boards to support it by the necessary supplementary conservation practices.

With the assistance of vital information on the capacity of land for permanent production, together with the various conservation and management practices necessary to control erosion and flooding, it is now possible to demonstrate conservation farming on a planned-farm basis on the various experimental and cooperative demonstration farms run in conjunction with catchment boards. Experience on these farms has proved that conservation management not only controls erosion but also increases the carrying capacity considerably.

This system had to be tailored to fit the land. In order to determine the kinds of land involved, conservation surveys were developed to evaluate the degree and extent of erosion, the capability of land for permanent production, and the conservation practices required on problem catchments. As scientific an evaluation as possible was made of the soil characteristics, erosiveness, slope, climate, geology, natural vegetation, and past management, and from such an inventory it became possible to classify the land into eight standard classes. These classes, four of which are suitable for cultivation, and four are not, provide a reliable index to the capacity of the land for permanent production.

Ten typical farms were acquired on problem hill country for the purpose of developing erosion control methods and suitable conservation farming practices for the types of problems in the country. Special conservation techniques such as pasture furrows, graded banks, broad base terraces, grassed waterways, discharge regulating dams, dams for stock water, gully control structures, and the use of trees for various purposes were gradually evolved to meet practical conditions. These methods of erosion control were then combined with good farming practices such as fire and pest control, spelling to encourage natural seeding and regeneration, top-dressing and oversowing, contour cultivation, and crop rotations, together with the use of cattle and fencing to modify and control grazing management. The integration of these special conservation and management practices, adapted to suit the district, provided a sound basis for a conservation farming system.

In 1941, as a result of comprehensive legislation, the Soil Conservation and Rivers Control Council was established. The wide powers of this Act made mandatory the promotion of soil conservation, mitigation of soil erosion, the control of flooding, and the use of land to achieve these objectives. Provision was made for establishing catchment boards and catchment commissions for organising and operating soil conservation, river control, and requisite drainage works in a district comprising one or more catchments with a community of interest.

In common with most newly developed countries, New Zealand has not escaped the consequences of rapid exploitation and waste of its forest resources and the conversion to farmland of its well-vegetated landscapes. This transformation of forest cover, with allied grass, fern, shrub, and swamp lands, into a wide expanse of grass brought problems in districts where some of the following conditions existed – high and intense rainfall, strong winds, and severe frosts at higher altitudes; young oversteep slopes, mountainous and hilly terrain; steep slopes; highly fractured rotten rocks; earthquake shattered zones; and steep active rivers, or erosive soils. The result of this transformation was an increased runoff which accelerated soil erosion (by sheet, slip, flow, and gully erosion) to such an alarming extent that legislation was necessary to bring about a control programme.

The first interprovincial tournament was held at Wellington in 1939. The trophies competed for are: the John Lennon Trophy (for men's club teams); the Beatty Cup (for men's interprovincial teams); the Dustin Cup (for women's club teams); and the Bensell Cup (for women's interprovincial teams). In addition, there are annual North versus South matches (Headifen Memorial Trophy since 1962) and a similar contest for women's teams. Results have been: