Board adopts new windbreak policies

Press, 1 November 1984, Page 24

Board adopts new windbreak policies

New aims and policies for windbreak planting in Canterbury to prevent soil erosion have been adopted by the North Canterbury Catchment Board. The board has reviewed and replaced its 1972 windbreak scheme with a more comprehensive one. It has set up 17 wind-

break tree planting districts within its region,' compared with three in the previous scheme. , Financing of windbreak planting has been updated and all records of planting computerised. The main aims under the scheme are to minimise soil erosion by wind, protect the scenic values of lhe landscape, encourage the highest level of production from the land, protect land valuable for primary production, and promote efficient use of water. Under the new policies, the board will give extensive promotion to windbreak planting. Surveys within the 17 districts will be done to provide information and a basis for promotion. Under the old scheme, the board gave a 60 per cent grant to any fanner planting windbreaks. Of that, 25 per cent was not paid until the windbreak was successfully established. This was to act as an incentive to farmers to replace trees which had died. Before 1975, when new tree-planting techniques were implemented, high death rates were expected in windbreaks. Since 1980, however, the majority of wind erosion control planting has been done under a plan in which the farmer continued contact with the board’s staff, who ensured that dead trees were replaced. “The 25 per cent retention on wind erosion control plantings is outdated and unnecessary,” said the author of the scheme report, Mr Don Wethey, who is the soil conservation officer with the board.

If a job was not done to specifications judged at inspection, the board had the right to withhold total grant payment to the applicant until the job was done satisfactorily, Mr Wethey said. The board has given priority to areas for windbreak planting. The Amuri plains, Medbury-Hawarden, Amberley, Eyrewell, Kimberley, Charing Cross, and the Te Pirita-Wind-

whistle districts have been given priority as erosion hazard is most severe there, the report states. Of arable land in the region, 370,000 ha was prone to wind erosion. The total length of windbreaks required to protect the area was 11,500 km. Only 1700 km or 15 per cent of this had been planted so far, Mr Wethey said. Planting promotion by the board in areas such as Te Pirita had increased planting there by 300 per cent in four years, he said. Other, intangible, benefits from windbreaks could not be measured economically. The amount and value of soil lost could not be measured nor could gains in aesthetic values, wildlife habitat, pollen for bees, the opportunity for diversification because of increased shelter, and psychological benefits. The board adopted a number of recommendations made in the report which outlined windbreak planting methods.

Planting should be across the direction of the principal eroding wind, which, in Canterbury was predominantly north-westerly. Windbreaks should be Slanted at intervals of 250 m ) 300 m, which was the most effective distance for preventing erosion. The maximum number of recommended tree rows in a windbreak has been reduced from four to three. The board’s previous policy was a maximum of four and a minimum of two rows. The new establishment techniques had made tworow belts more popular. On highly versatile soils farmers had increasingly applied for one row belts to minimise the amount of land lost to production, the board was told. Single rows were acceptable if the trees had good wind filtering characteristics and grew rapidly, Mr Wethey said. Such a tree was the Lombardy poplar. The board will allow single rows to be planted if that tree is used.