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Precious Soil Being Lost to the Ocean

Precious Soil Being Lost to the Ocean

By Andy Loader, Co-Chairman Primary Land Users Group

On the 14th December 2017 the New Zealand Herald published the above headlined article by Bala Tikkisetty, Sustainable agriculture co-ordinator for the Waikato Regional Council.

In this article he states:

We're losing it. Soil that is. And we need to do more to stop the slide of this precious asset into waterways and, ultimately, the ocean.

It makes economic sense to do so and also helps better protect our waterways and aquatic life from the effects of sedimentation.

The scale of this loss of a farmer's most precious resource is huge in this country.

We lose it to the ocean about 10 times faster than the rest of the world, with between 200 million and 300 million tonnes sliding into the sea every year.”

New Zealand’s total land area is just less than 268,000 Square Kilometres and using Mr Tikkisetty’s top estimate we are predicted to lose the total land area of New Zealand to a depth of 1 metre over approximately the next one hundred years from this soil erosion.

Yet he does not mention anywhere the effects of pest fishes on the scale of the erosion problem particularly in the Waikato and Waipa River catchments.

It is estimated that there are approximately 500,000 tonnes of Koi Carp alone in this area and these produce approximately fourteen times their own bodyweight of sediment per year (seven million tonnes), by their feeding method.

QUESTION: Where do these figures come from, as they seem excessive to me?

Mr. Tikkisetty also states:

“Waikato Regional Council staff can advise on best practice at individual sites. The council also has funding (up to 70 per cent of costs) available to help farmers in priority susceptible west coast and Waipa catchments to carry out erosion control and other land management activities.

Funding covers:

- tree planting, including pole planting and native plant species

- fencing off marginal land or bush from active use

- riparian management (fencing, planting and stock water reticulation)

- farm plans to identify soils, land use capability and environmental projects.”

While it is great to see the WRC doing something practical to improve the water quality in the catchments the fact of the matter is that the majority of the waterways around farms are already fenced and further fencing will not have a huge effect on improving water quality unlike other issues.

Why does the Council not provide some funding to remove the pest fishes from these catchments? Surely with the pest fishes creating so much sediment in the waterways as well as the other environmental damage that they do, their removal would achieve huge improvements very rapidly.

When Koi Carp feed they stir up the bottom of ponds, lakes and rivers, muddying the water and destroying native plant and fish habitat. Koi carp are opportunistic omnivores, which means they eat a wide range of food, including insects, fish eggs, juvenile fish of other species and a diverse range of plants and other organic matter.

They feed like a vacuum cleaner, sucking up everything and blowing out what isn’t wanted. Aquatic plants are dislodged in the process and are unlikely to re-establish. Koi carp cause habitat loss for plants, native fish, invertebrates and waterfowl and they are highly tolerant of poor water quality and contribute to water quality decline.

Many people are unaware of the damage done to our waterways by pest fish. Unfortunately, introduced fish have spread into the wild, become pests and are threatening New Zealand’s freshwater species and environments by:

• Stirring up sediment and making the water murky

• Increasing nutrient levels and algal concentrations

• Contributing to erosion

• Feeding on and removing aquatic plants

• Preying on invertebrates, native fish and their eggs

• Competing with native species

Mr. Tikisetty also states:

“Erosion results from our mountainous and hilly landscape, adverse weather events and land use practices.

The resulting sedimentation of our waterways contributes to poor water quality and interferes with aquatic flora and fauna, as well as productive capacity of our land.

Therefore, preventing or at least minimising current and potential erosion is a key to both the economic and environmental sustainability of our farming.

In cases where severe erosion is present it may be best to retire land from grazing and, if possible, change land use to plantation forestry.”

Whilst I agree with most of his comments there are a number of questions that need to be addressed and they are as follows:

1. Why this article seems to single out farming as a main contributor to the effects of erosion when in fact there are other causes such as natural water courses, urban development, vegetation removal outside of farming, etc.

2. For many farming operations the effects of erosion are solely related to the quality of water taken for their farming purposes and as such they have no chance to minimise the effects of erosion at source. How does he propose that they take action to minimise erosion and its effects?

3. Under the proposed plan change (PC1) the requirements relating to land use and the restrictions on intensification mean that there is extremely little chance that any landowner will want to retire land in to plantation forestry without some type of compensation being paid to account for the loss in capital values of their property as a result of the change in land use to plantation forestry. How does he propose that farmers retire severe erosion affected land without losing a large percentage of the capital value of their property?


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