Cattle grazing on river edges keeps weed 'shambles' down on extensive farms

Bob Todhunter has worked in the Canterbury high country all his working life.
Supplied Bob Todhunter

Bob Todhunter has worked in the Canterbury high country all his working life.

OPINION: With alI the bad publicity our rivers are receiving I feel the general public is confused between extensive and intensive grazing.

I would like to make some observations about stock grazing alongside waterways. I am no scientist, however I do have 70-plus years of practical observation.

I remember being taught fishing by my grandfather in the 1950s on the rivers of the Canterbury Plains when sheep and cattle were grazed extensively by the riverbeds.

Weeds are blocking access to Stour River, a tributary of Ashburton River.
Supplied Bob Todhunter

Weeds are blocking access to Stour River, a tributary of Ashburton River.

The streams were able to be walked and fished from the banks.

The water was clear and pristine.

Now these same streams have a 6000 volt electric fences and their banks are overgrown with willows, gorse and broom. If you travel on Inland Scenic Route 72 you will notice how all of Canterbury's rivers are choked with weeds, willows gorse and broom. The Queen's Chain has little relevance as you cannot get near the rivers. How much moisture are these weeds sucking out of the stream beds?

This year we went down to the Catlins to fish.

The Owaka River was fenced on one side and it would have been hopeless to fish from, however, the north bank was grazed to the stream edge allowing enjoyable fishing and the water was pristine.

Last year we drove through Molesworth and the Clarence River from Jacks Pass was a shambles of wilding trees, gorse and broom. On turning into the Acheron River cattle were grazing to the edge of the river and it was walkable and fishable. 

We sat down and had lunch as a herd of 30 heifers decided to cross.They went in single file and were not defecating, nor was the river discoloured, On reading the newspapers one would assume cattle go down to the river to both drink and defecate.

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The fact is that extensively grazed cattle tend to defecate where they camp. When a swamp is extensively grazed, sheep and cattle keep away from swampy areas, grazing river edges and dry areas. This enhances the swamp for water fowl and also controls rank grasses like cocksfoot and brown top.

When scientists are asked about swamp grazing it is always the loss of biodiversity we hear about through grazing, never the loss with smothering by cocksfoot and browntop. Once a river or swamp is fenced, a farmer no longer has any interest in it and it becomes the responsibility of Land Information New Zealand, Department of Conservation or Environment Canterbury (Ecan).

Fencing is only the first cost. There is also maintenance and weed control. I would think it wise for Ecan to have a rigorous testing programme and if there is pollution or reduction in water quality to find out what is causing the problem. For instance the Ashburton lakes were tested as being okay except Lake Emma.

A reporter put this down to cattle and topdressing, however Lake Emma was fenced and there were no cattle or topdressing - the problem was Lake Emma is a shallow lake with a large population of game birds.

I also note that the Birchwood swamp became too rank for black stilts once it was retired from grazing.

Also the Ashburton riverbed became so overgrown with weeds that the black billed gull departed and Ecan is now experimenting with bulldozed islands and has been successful.

When a high country farmer wishes to have a large scale development programme it might be better to have a wider margin with extensive grazing before fencing and development. It is interesting that English authorities encourage extensive grazing to control rank growth on their river margins. Notices in a Montana national park in the United States also extol how the use of extensive grazing can lift the natural productivity of waterways. 

In driving for water purity don't overlook river margins and the part extensively grazed sheep and cattle can play in the control of weeds and rank growth. If you do our high country rivers will look more and more like our down country rivers - a mess.

Bob Todhunter has worked in the Canterbury high country all his working life. He has ownership interests in Lake Heron and Cleardale stations and a previous interest in Glenfalloch Station.

 - Stuff


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