Private irrigation outstrips Government development

Press, 27 April 1984, Page 17

Private irrigation outstrips Government development

If the 1940 s and 1950 s were the years of big riverbased irrigation schemes, the 1960 s and onwards have seen the rapid rise of private irrigation development. It is expected to outstrip public development in the present economic climate. Indeed, private development will continue at a greater rate than public development until suitable supplies of water prove a lot more expensive and difficult for the private farmer to obtain than they are now. Some 219,000 ha of land have been irrigated in New Zealand, of which the South Island has about 199,000 ha. Most of it is in Canterbury, followed by Central Otago. Central Otago has an irrigated area of 58,150 ha, including 19 community schemes. It is estimated that there is a potential in the Otago-Southland region for 114,000 ha to be irrigated. Within North Otago, three schemes are under construction — Lower Waitaki, Maerewhenua Settlement, and Maniototo. Three other schemes in Otago will soon go forward for Government approval — upgrading the Arrow scheme; either building a new 12,000 ha Manuherikia or upgrading the present Omakau and 1200 ha Manuherikia schemes; and the 1750 ha Earnscleugh scheme. The proposed 6000 ha Benmore scheme which would have served the high country runs in the OhauOmarama Basin, and the proposed 17,000 ha WaiarekaKakanui scheme, have been scrapped.

Several other schemes in Otago are • being investigated. These include upgrading the Ida Valley scheme; upgrading the old Pisa Flats, Ripponvale, and Hawdun schemes (totalling

4900 ha); and a proposal to extend and replace the IOOOha Tarras and 510 ha Ardgour schemes with the proposed 8000 ha Luggate (Upper Clutha) scheme. Canterbury presently has 130,256 ha under irrigation, including 17 community schemes. It has been estimated that Canterbury has 570,000 ha suitable for irrigation. Of the land irrigated, three-quarters is used for pastoral production, most of the rest for cropping, and a little for horticulture and market gardening. Many horticultural prospects are being investigated on the Canterbury Plains, including crops such as blackcurrants, other berry fruits, asparagus and pip fruits. But their development will depend on finding and establishing suitable overseas markets. Another nine schemes are being built in Canterbury, and are in partial operation: Morven-Glenavy (9400 ha The Wolds (400 ha South Rakaia (1052 ha Fereday (1020 ha North Rakaia (2368 ha Green Street (2180 ha Loburn (300 ha Waiau Plains (17,000 ha and Waiareka Downs (420 ha Glenmark (1500 ha became partially operational this past summer and Balmoral (5500 ha will follow in two years time. More schemes are being prepared, or await approval in principle: Emu Plains (3000 ha Browns Rock (2620 ha Levels Plain (4850 ha Lower Rakaia surface scheme (22,000 ha and Te Parita (2200 ha Eiffelton (2462 ha is almost ready for approval. Five further schemes in Canterbury are being investigated: Barrhill-Highbank (20,000 ha Central Plains (70,000 ha Maryburn-Simons Pass, Hakataramea Valley,

From

and the district between the Waimakariri and Eyre Rivers. About IO.OOOha in Nelson and Marlborough are irrigated, but there are no community schemes. Waimea East (1050 ha is under construction and five others are being investigated: Moutere (1064 ha Tasman-Mariri, Waimea Plains (6000 to 15,000 ha) in two schemes, and Dashwood (lOOOha). It is estimated that Nelson and Marlborough have a combined potential of 90,000 ha of irrigable land.

One-third of land in Nelson and Marlborough that is irrigated is for grazing, onehalf for horticultural crops (berry fruit, pip fruit, kiwifruit, hops and tobacco), and the rest for agricultural cropping. New schemes are expected to emphasise horticulture. In contrast with the snowfed rivers of the South Island, most North Island rivers have low flows during periods of low rainfall. Water storage is needed to carry over excess water from periods of high rainfall into periods of high irrigation demand.

This can make irrigation in the North Island much more expensive than in the South Island. Water charges in 1983 were as high as $3OO per hectare, and can now only be justified for horticulture and high value crops.

Only 19,572 ha is irrigated in the North Island, with two schemes at Kerikeri in the Bay of Islands, three in the Bay of Plenty, two in Hawke’s Bay, and two in the Wairarapa. More than half of this is for grazing, onefifth for fruit production

OLIVER RIDDELL

in Wellington

(pip, stone and kiwifruit), and the rest for vegetables and farm crops.

Two small schemes in the Bay of Plenty are being built while four others, two in the Waikato and two in Northland, await approval. Six other small North Island schemes are being investigated. ' But although the work being done to increase community schemes is the most visible and most expensive, private development from either groundwater or readily accessible rivers is growing at a much greater rate.

The boom in this kind of development really dates from the late 1960 s when a succession of droughts coincided with the development of low-labour and fairly low-cost sprinkler irrigation equipment. Increasing and justified confidence in groundwater supplies, particularly in Canterbury, helped accelerate the trend. As early as the late 19505, the then Department of Agriculture was able to publicise the results of research into the impact of irrigation on farm profitability from farms in the huge Ashburton-Lyndhurst scheme in Mid-Canterbury. This proved that it needed only partial irrigation on small holdings to double the stock-carrying capacity per hectare, and double the income per hectare too. In spite of the reluctance of many farmers to incur the costs, and the increasing installation costs of building community schemes, this evidence has eventually led to an accelerated demand for irrigation — whether surface, trickle or sprinkler.