Earthworm count is encouraged in efforts to improve farm productivity

Bala Tikkisetty, a sustainable agriculture advisor at Waikato Regional Council, has gone out to bat for the humble earthworm in an article distributed to news media.

He explains that soils without enough of the right type of earthworms are usually poorly structured and tend to develop a turf mat or thatch of slowly decomposing peat-like material at the surface. Old dung and dead plant material lie about the surface. These factors can naturally inhibit pasture and crop production.

Lower producing grasses are often more evident than ryegrass on these types of soils as well. Pasture growth is slow to start in spring and stops early in autumn.

Plant nutrients tend to remain locked in the organic layer and there is poor absorption of applied fertiliser.

Plants roots in such soils are relatively shallow and pastures are therefore susceptible to drought.

And, as indicated earlier, water runs off this type of pasture more easily rather than being absorbed into the soil, increasing water quality problems.

To help avoid these types of problems, soils should have a good diversity of relevant earthworm species.

The most common introduced earthworm in New Zealand is Aporrectodea calignosa, a topsoil dweller, Tikkisetty says.

This earthworm grows up to 90mm long and may vary in colour from grey to pink or cream.

Another common introduced earthworm is Lumbricus rubellus, a surface dweller. Often found under cow pats, this earthworm will grow up to 150mm long. It is reddish-brown or reddish-purple with a pale underside and flattened tail. Aporrectodea longa live in burrows as deep as 2-3m below the surface.

Earthworm functional groups are: Epigeic earthworms (i.e. Lumbricus rubellus) feed on organic matter on the soil surface and do not form permanent burrows; Endogeic earthworms (i.e.Aporrectodea caliginosa) ingest topsoil and its associated organic matter, forming semi-permanent burrows; Anecic earthworms (i.e. Aporrectodea longa) draw organic matter from the soil surface into their deep, permanent burrows to feed on.

The article includes this illustration from AgResearch.


The article is designed to encourage an earthworm count to  let farmers know if they have enough of the right type.

Counts should preferably be done late winter to early spring when soil moisture and temperature conditions are ideal. Counts can be done by taking out a 20cm cube of soil with a spade. Aim to have an earthworm number of between 30 and 35 in that cube.



Precious soil being lost to the ocean – but should we focus more on fish than farmers?

Andy Loader, co-chairman of the Primary Land Users Group, has challenged information in an article, by Bala Tikkisetty, Sustainable agriculture co-ordinator for the Waikato Regional Council, published in the New Zealand Herald in mid-December.

The article (HERE) said more must be done to stop the slide of soil 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. The top estimate implies we will lose the total land area of New Zealand to a depth of 1 metre over the next hundred years – roughly – from this soil erosion.

Mr Loader (see HERE) notes the article does not mention the effects of pest fishes on the scale of the erosion problem, particularly in the Waikato and Waipa River catchments.

According to Mr Loader’s estimates, there are approximately 500,000 tonnes of Koi Carp alone in this area. These produce about 14 times their own bodyweight of sediment per year (seven million tonnes), by their feeding method.

Where do the regional council figures come from, he asks, because “they seem excessive to me?”

The article by Bala 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.

Mr Loader says it is great to see the council doing something practical to improve the water quality in the catchments, but

“… 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.”

He wants the council to provide funding to remove 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.”

Many people are unaware of the damage done to our waterways by pest fish, Mr Loader contends. But 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 Loader agrees with much of what the article says, but questions why it seems to single out farming as a main contributor to the effects of erosion when there are other causes such as natural water courses, urban development and vegetation removal outside of farming.

Good soils are at the heart of agricultural enterprise in the Waikato

Waikato Regional Council’s soil quality monitoring programme measures soil properties such as soil compaction, nutrient status, biological activity, soil carbon and organic matter at 152 sites, with about 30 sites sampled annually. The sites cover a range of soils supporting various land uses.

The main soil quality issues identified are compaction, excessive phosphorous and nitrogen (N) on dairy and cropping land, and declining carbon, mainly on cropping land, says Bala Tikkisetty, a sustainable agriculture advisor at the council.

The good news is that some of the emerging data trends suggest there is an improvement in some soil quality indicators, most likely the result of good land management practices undertaken by our farming community, he says.

But some measures in various areas are still causing concern, with improvements needed.

That’s because minimising human-induced soil erosion and maintaining good soil quality are essential for maintaining so-called soil “ecosystem services”, such as nutrient and water buffering, productive capacity, assimilating waste, and minimising impacts of sediment and other contaminants on water bodies.

The transformation of so-called “natural capital” – namely soil, plants and animals, air and water into resources that people value and use – is at the heart of what’s meant when we refer to ecosystem services.

The concept is gaining more attention nationally as we see environmental pressure increasingly applied to resources, such as soil health, that we once took for granted.

Tikkisetty says the several practices which help support and improve soils and provide clear benefits include:

• avoiding over grazing and heavy grazing in wet weather (leading to compaction)

• avoiding under or over-fertilisation

• appropriate use of pesticides and other agrochemicals

• managing pasture to maintain complete soil cover

• careful application of farm dairy effluent to optimise organic matter and avoid saturation .

There is also benefit in protecting on-farm wetlands, which deliver a wide range of ecosystem services, such as improving water quality, flood regulation, coastal protection, and providing recreational opportunities and fish habitat.

A suite of tools called functional land management seeks to optimise the agronomic and environmental returns from land and relies on the multi-functionality of soils. It focuses on soil functions that are specifically related to agricultural land use, Tikkisetty says  They are:

• primary production

• water purification and regulation

• carbon cycling and storage

• functional and intrinsic biodiversity

• nutrient cycling

New research is focussed on nutrient cycling in soil, such as the ability of soils to recycle N, carbon and phosphorus and how this can best be managed.

To reduce N leaching from soils, Tikkisetty says, the research is seeking to understand mechanisms for N retention in soil and how to manipulate soil processes to enhance de-nitrification. As soil microbes are the key agents for nutrient cycling, scientists are focussing on determining the impacts of soil management on soil microbial activity.

He says the Waikato Regional Council is strongly committed to working with the wider farming community to increase the understanding of soil ecosystems services and ways in which farmers can manage them both to benefit their business, and to protect or enhance the natural capital on which it is based.

This work has already resulted in production of the menus of practices to improve water quality. They identify farming solutions and provide assessments of their effectiveness in managing various contaminants from farm land. The online version of the menus can be found

The council will be keeping a close eye on the new research and providing advice to the farming community when we know more.

Bala Tikkisetty can be contacted on 0800 800 401 or