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Australian soil ecologist Zero N campaign


Australian soil ecologist Zero N campaign

An international authority on soil health and profitable farming systems is calling for non-biased government funded research.

Dr Christine Jones told hundreds of farmers at a series of workshops in the Waikato that they are being duped.

Worldwide excessive use of nitrogen and phosphorus fertilisers has resulted in soil degradation, environmental pollution and trace element deficiencies in plants animals and people. There are aquatic dead zones in the Baltic Sea, the east coast of America, the Gulf of Mexico and parts of Asia.

She said New Zealand has gone against worldwide trends of declining rates of application of high-analysis fertilisers.

In contrast to most OECD countries, the amount of inorganic nitrogen applied to agricultural land in New Zealand increased 41% over the period 2000-2010. France, Germany and the United Kingdom have maintained high yields with forty to fifty per cent less fertiliser than used in the 1980’s.

New Zealand farmers spend over $400 million/year on inorganic based nitrogen fertilisers.

With almost half of this inorganic nitrogen ending up in the air and half in our waterways she questioned the audience why they use it.

“The use of inorganic N limits plants uptake of mineral and trace elements, stimulates weeds and increases plants susceptibility to pest and disease requiring the application of expensive insecticides and fungicides which reduce farmers profits.”

You will visually see extra kilograms of dry matter but the N has simply elongated the cells without supplying any more nutrition.

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“It is expensive and inefficient and is destroying New Zealand’s clean green image.”

She said the use of N was still being actively promoted by many NZ research institutions even though there is very little data linking the use of N with increased profit.

Workshop attendees were told there was a deeply held belief in New Zealand that plants can only use N in the inorganic form.

“Much of the literature has biased information – even what is taught in universities. Farmers could be forgiven for not knowing about organic N”.

The preferred pathway for plant uptake of N is via amino acids which convert to complete proteins, whereas N in inorganic forms - such as nitrate - can often result in the formation of incomplete protein in plants, causing metabolic issues for cows.

A compounding factor is that the crude protein content of ryegrass/clover pastures is far higher than required by lactating dairy stock.

“Excess dietary N results in elevated levels of blood urea nitrogen (BUN) and milk urea nitrogen (MUN) which have been linked to an increased incidence of lameness, mastitis, and infertility and other animal health issues. Excess dietary N is also excreted as urinary N, causing environmental pollution.”

She said mixed swards containing a variety of pasture plants such as plantain, chicory, brassicas, lucerne, red clover and three or four kinds of grass can significantly reduce the excretion of urinary N while maintaining and often improving milk production.

“Reductions in urinary N between 20-50% have consistently been reported for dairy stock consuming mixed pasture swards in New Zealand,” Dr Jones said.

The greater the diversity of plants above ground the greater diversity of microbes below ground. Microbes matter!”

“There are thousands of different bacteria that can fix N. This phenomenon is not restricted to rhizobia associated with legumes.

But the use of inorganic N and/or water-soluble P inhibits the activity of beneficial soil microbes. Farmers are shooting themselves in the foot using high-analysis fertilisers.”

She suggested that as pastures come up for renewal farmers might consider incorporating as much pasture diversity as possible, particularly warm and cool season herbs and a variety of grasses.

“Nitrogen has to be fixed biologically in order to be stable. Organic forms of N will not disappear up into the air or leach into waterways.”

Much of the nitrogen currently used in agriculture derives from the Haber-Bosch process developed in the early 1900’s. This process catalytically combines atmospheric nitrogen with hydrogen derived from natural gas or gasified coal, to produce ammonia under conditions of high temperature and pressure. The Haber-Bosch process uses non-renewable resources to produce a product that is expensive to manufacture, transport and apply.

“After World War II we got hooked on chemicals and these chemicals have replaced diversity. Our agricultural systems have become over-simplified”.

“When soil lacks microbial diversity, the nutritional value of the food declines.”

Dr Jones said the nutritional value of today’s food was lower than any point in history.

To get the same nutrition as in the 1940s we would have to eat two times more meat, three times more fruit and four to five times more vegetables.

The human race has been hit hard by metabolic disorders as a result of the decline of minerals and trace elements in our food – we are not functioning metabolically as we should.

In parallel with research into the human gut microbiome, understanding and supporting the functioning of the soil microbiome is becoming increasingly recognised as an exciting new era in science.

Dr Jones urged farmers to replace inorganic N fertiliser with biology-friendly products that support the soil microbiome.

She said in the same way as it was important to feed the rumen not the cow, it is also important to feed the soil microbiome not the plant.

“Restoring soil biodiversity so that N fertiliser is not needed would be more beneficial to the New Zealand nation than attempting to regulate the use of nitrogen.”

“New Zealand farmers apply around 800,000 tonnes of urea a year, much of which is of no benefit to them economically – while being hugely detrimental to the wider environment.”

Dr Jones outlined research showing soil microbes can supply all of a plant’s nutritional requirements provided there is sufficient plant diversity.

“Increased plant diversity and biological fertilisers are the answer to a clean, multi-green New Zealand.”

Rachel Scrimgeour

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