SHELTER VALUE STRESSED

Press, 20 April 1979, Page 6

SHELTER VALUE STRESSED

’ Shelterbelts could save New Zealand hundreds of thousands of dollars a year in lower energycosts, according to a crop scientist of the Department of Scientific and Industrial Research.

Dr J. W. Sturrock, of the Crop Research Division at Lincoln, says fuel savings of 8.5 per cent of the annual cost of heating glasshouses in New Zealand .— about 3500,000 a year — are possible if all glasshouses were sheltered from the chilling effects of wind. Dr Sturrock gave his findings in a paper,

“Windbreaks: Their Potential in Conserving Energy,” to a symposium on energy in protected cultivation in Sweden during an overseas study tour. The potential fuel savings, and the weighted fuel savings when adjusted for existing windbreak protection, were calculated from tables of wind conditions in the three main glasshouse areas of New Zealand: Auckland, Waik-ato-Bay of Plenty, and Christchurch. An estimate was made for the remainder of the country’s glasshouse area.

“The overall fuel savings of 8.5 per cent is possibly conservative because 'the allowance for existing shelter may be generous and because most glasshouses are small with large surface areas,” states Dr Sturrock,

In addition, there are other possible direct and indirect energy savings from wind protection of crops, soil and livestock, which Dr Sturrock says add up to substantial amounts each year. Some of the economies are: greater plant growth and yield; reduced use cf I

plant energy to repair damaged tissue: improved insect pollination; earlier maturity, better returns, and second crops; more effective irrigation and fewer applications; possible use of low pressure applicators and misting units; uniformity of spray application and less water required; control of soil blow and prevention of soil loss; economies in harvesting larger crops; better utilisation of fertilisers; and greater worker comfort and efficiency.

In the livestock area. Dr Sturrock considers there would be less stock losses at the vulnerable times of lambing and shearing, increased stock carrying capacity in drought-prone areas, increased animal energy available for growth, with consequently a shortened time taken to reach the required carcase weights. The management of trees for both shelter and timber increases the economic worth of windbreaks, and the sale of timber could provide income stabilisation when the returns from other farm enterprises are poor.

“The timber potential of shelterbelts has been unde r-valued. because most farmers lack knowledge of trees and neglect their management,” says Dr Sturrock,

“However, innovative farmers in New Zealand have found that introducing timber management allows more economic use of farm labour and machinery. A home supply of timber obviates the middleman and diminishes the delays and transport costs of bringing in supplies from outside the farm.”

Dr Sturrock says a system of growing trees in pasture is under evaluation in New Zealand now. aiming at maximising the total returns from pasture and timber. W i d e-spaced, highpruned trees in pasture bring the advantages sought from convential shelterbelts — shelter, shade, soil stabilisation — plus economies of scale, better mineral cycling, a timber yield as good as from convential forestry, and an almost immediate income from livestock while the trees are growing. The system relies on the rapid growth of the principal timber tree in this country, which allows felling in under 20 years on good sites. “In some regions tier plantings could be used on large areas of marginal land and hill pasture, ■where conventional shelterbelts have been of limited value.”