More Output Expected From New Scheme

Press, Volume CVIII, Issue 31653, 13 April 1968, Page 8

More Output Expected From New Scheme

A scheme for improved drainage of about 4000 acres of flat, low-lying country close to Lake Ellesmere in the area between the mouth of the Halswell River and the Greenpark huts and extending towards Greenpark is expected to lead to a marked increase in farm production in the area.

The deepening of drains in the area and the installation of a pumping station to pump water out of the area into the lake is now in progress. Mr E. J. Stalker, deputy chairman of the Ellesmere County Council, who was chairman of the old Springs county from 1951 to 1964, and a member of the North Canterbury Catchment Board for 15 years, says that from the time this country was first settled it has always been a problem area from a drainage point of view. “The land is so flat and so near sea level that even with a moderately low lake, drainage has been difficult.” In spite of improvements made over the years in the drainage of the area, they still did not allow the area to be farmed adequately. Mr A. C. Norton, a classifier of the Catchment Board, who has investigated the economics of the scheme, says the fall in the area is less than a foot to the mile. Some 57 per cent of the area is below the 6.5 ft above mean sea level contour, and the latter level is only 3.5 ft above normal high tide. When there is heavy rainfall on this country and there is also a high lake level, which results in the water from the present drainage system being unable to get away into the lake, there is extensive flooding and a high water table.

The region also has a problem of saline soils. It is estimated that about 2100 acres of the lowest country in the area is of medium salinity with patches of high salinity, about another 1450 acres are weakly saline with areas of medium salinity and some 450 acres on slighly higher ground have no salinity problem or are only slightly saline. The net result of flooding and salinity is that farming in the area is severely restricted. The cover comprises only salKtolerant plants such as salicornia on the worst affected areas, with plants like rushes and creeping bent, red top and shore barley grass showing up where there is some slight improvement in the habitat. Experience on a local property has demonstrated the need in the first place to get rid of water. Here the value of getting the country out of the water was graphically shown in an experiment where soil was scooped off a paddock to a depth of one foot over a 10 yard width and then distributed to a depth of six inches over an adjacent 20 yards. The farmer said that this raising of the level by only six inches was equivalent to getting the land out of the water and here subsequently a crop of barley was successfully grown and then a crop of rape, whereas on another area where the land was cultivated and sown to barley the crop never reached the stage of being worth putting the header harvester into.

The scheme, which is now in process of being implemented, involves the deepening of existing drains and the construction of some new branch drains. Altogether there will be slightly more than seven miles of main channels in the scheme in what is called No. 4 rating district. The scheme is designed to keep the surface level of the water in these channels three feet below ground level under average winter conditions. This is to provide adequate outfall for drainage and also de-salting of the country. In all some 64,000 square yards of material are being shifted. The scheme is being implemented by the Ellesmere County Council, which will be responsible for its maintenance. Excavation Is being done by hired draglines and the estimated cost of this part of the scheme, together with some other work, is about $20,000. The other major part of the scheme is the pumping station in process of construction close to the site of the floodgates on the main drain and also the Halswell canal. It is being built by Burnett Motors, which is also responsible for installation of two pumps and motors. This part of the work is costing between $14,000 and $15,000. The pumps and motors are being supplied by MacEwans Machinery, Ltd. Each of the pumps will be able to pump nearly 200 gallons of water a second and will be powered by two English electric 30 horsepower motors. The pumps will work automatically when the water reaches a pre-determined level in the collecting or suction bay, the concrete floor of which has been built at 7ft below mean sea level. The pumps will pump the water over an existing bank into the lake. The pumps and motors will cost slightly in excess of $BOOO, bringing the cost of the whole scheme to about $42,000. The bank mentioned is indispensable to the scheme. It was erected late in the last

century and keeps the lake back off the land. On the lake side it is faced with stone, and Mr Stalker says he understands that the contractor used as many as 80 teams of horses and drays on this job. The stone for the bank was brought from the Port Hills at Tai Tapu and there is still supposed to be evidence of the tracks used by the drays in those days. Every landholder in the area will have access to a main drain and with the knowledge that these drains will be deep enough to take the water away efficiently they should have confidence to proceed with internal drainage schemes on their properties and farm development. Because farmers are going to be faced with pretty heavy costs in undertaking development schemes to capitalise on the major drainage scheme, the Soil Conservation and Rivers Control Council has approved a two for one subsidy on the project. A 20-year loan of $14,000 has been raised for the local share of the work and annual charges to cover interest and loan repayment will be 42c per acre on class A, 22c on class B, and 3c on class C, and the annual maintenance charge will be the same in each case. On this scheme rating on an acreage basis rather than on capital value has been adopted. This obviates the problem of the man who develops his land most being penalised under a capital rating system by later having to pay increased rates on the improvements he makes.

Mr Norton made a survey into the economic Impact of the scheme on the region in 1963, using the assumption that the type of farming at present practised in the area will continue under the present level of efficiency of management. On the least developed area of some 2100 acres he calculated that the cost of farm development would be about $lO4 an acre, taking into account internal drain-

age, shelter, subdivisional fencing, de-salting, cultivation, fertiliser, seeds, lucerne establishment and provision of stock water. Today he believes the figure would probably be at least $llO an acre. In addition, costs would also be incurred in providing extra capital stock, and in some extra buildings and plant. It was estimated in the course of this investigation that this expenditure would be incurred in the course of 10 years, and at the end of that period it was estimated that production increases of the following order would be achieved—lls cows and replacements (mainly on town supply farms), 50 breeding beef cows, 4225 ewes for fat lamb production, 500 other sheep, and 145 acres in barley and 30 acres for ryegrass seed production. On the basis of the 1963 calculations it was estimated that annual gross returns would be boosted by $66,000, and Mr Norton believes that the figure would probably still be somewhere near this. To obtain this increase it was estimated that about $37,000 would be involved in running expenses. This does not include any provision for interest or repayment of the farmer’s development expenditure or for the annual charges for the scheme. In addition to this economic investigation the Catchment Board has also undertaken technical investigations at the request of the Soil Conservation and Rivers Control Council for subsidy purposes, and the scheme has been designed by Mr G. D. Stephen, the board’s design engineer. Some farmers are already moving to take advantage of the new conditions, which will be provided by the scheme. One set in motion last autumn plans to increase his stock numbers and will have additional young ewes to put into his flock a year hence. Apart from internal farm drainage, extensive subdivisional fencing, construction of culverts and provision of shelter will be involved. Costs involved in this sort of work will be high. The 42in diameter concrete pipe used in a toft wide culvert, already built to enable free movement over one of the drains, costs, for instance, some $lOO. Because the soil is lacking in structure, one farmer in the area proposes in the early stages, at least, to approach improvement of the country through oversowing to introduce subterranean clover, cocksfoot and seconds of grass seed from the seed cleaning plant from seed harvested on country that has already been improved.

“I think that if the present scheme comes up to what is envisaged by the engineers it will make a very great difference to the farming potential of the area," says Mr Stalker. “The drainage of the area will be only the first phase in the improvement of the land. While many farmers have already succeeded in reclaiming their land from the effects of salinity, there is still a large area which will require de-salting before the full benefits of the scheme will be attained, and with this pumping scheme farmers will be able to use artesian supply, which is readily available, without interfering with the drainage system.” At the moment, when the country lies wet and exposed and dotted with rushes, it may seem a long way off, but some can see the day when, because of its location handy to Christchurch, this country could have a potential for market garden or horticultural crops and the drainage system might be used to influence

the level of the water table through sub-surface irrigation Rather ironically irrigatioi could become a part of farm ing practice in the area. Reporting on the progress made with the scheme the engineer of Ellesmere county, Mr P. Macfarlane, said this week that digging of drains was now about 15 per cent complete and about 50 per cent or slightly more of the work had been done on the pump house. The pumps and motors have now been delivered to the contractors for installation.