Is dairying the culprit? Part One

It is a concern that while farmers’ debt levels are skyrocketing, so too is their environmental footprint. Fish and Game coined the term ‘dirty dairying’. And while the dairy industry has and is emitting significant nutrients into our groundwater, waterways and atmosphere, it is not dairying per se that is the cause but the type of advice, including fertiliser advice, given to farmers.

Various mitigating measures include increasing plantings, fencing off waterways, reducing cow numbers, and establishing initiatives like the Clean Streams Accord and Healthy Rivers. For the most part, these are band aids that attempt to address the symptom and do little to tackle the cause of the problem – the excessive application of nutrients and in the wrong form.

An estimated 750,000 tonnes of urea – 345,000 tonnes N – was applied in 2014 mostly to dairy farms, a 38-fold increase from the 20,000 tonnes applied in 1983. While this, of course, is due in part of the increase in cow numbers there has developed an over-reliance on mineral N to get our pastures to grow. It is no coincidence that dairying’s high environmental footprint coincides with the excessive application of nutrients and in particular N and P.

Graham Shepherd of BioAgriNomics is a soil scientist and farm consultant and author of the widely commended Visual Soil Assessment method.


There are many efficient and cost-effective ways of applying N, measures that ensure the plant has all of the N required to enable good production and at a significantly lower cost to the farmer and the environment.

These include:

  •   •  Converting the volatile N – and P – in the effluent pond to less leachable and less ‘volatilisable’ organically-bound forms and applying as a folia.

  •   •  Increasing the clover cover and promoting the N-fixation capability of legumes by ensuring good soil structure, good drought resistance and water-use efficiency of the pasture, and the presence of the key soil nutrients required to ensure good N-fixation.

  •   •  Promoting the drawdown of the 78 per cent free N in the atmosphere by promoting the free-living and associative nitrogen-fixing bacteria and archaea.

The above are productive smart management practices that would permit significant cost savings and are “environmentally friendly”. They’d also help mitigate the high loss of nutrients on the permeable soils in the Canterbury, Mackenzie Basin and North Otago areas.

Nutrient oversupply

Large amounts of nutrients are being applied to our farms not because they are deficient but because their plant uptake is being suppressed by paradoxically the oversupply of some nutrients. The excessive application of mineral N and P for example will suppress biological biomass, diversity and activity. Research has shown the biological fraction regulates the chemical and physical condition of the soil, a fraction that is the ‘engine room’ of the farm. Regrettably we have traditionally ignored this at our cost.

Excess mineral N will also suppress the ability of the soil to produce dry matter, suppress clover growth and the uptake of nutrients like B. Excess N will further cause the plant to luxury feed on K which in turn will suppress the utilisation of Ca and Mg.

In addition, the excessive application of N will produce a lazy plant with a shallow limited root system because the N is readily available near the surface. If we didn’t suppress nutrient uptake in the first place, we wouldn’t have to apply so much nutrient at considerable cost to the farmer and the environment to attain the production levels sought.

While some may believe in ‘dirty dairying’, it is not the cows that are the problem but the sort of advice given including the overuse of water-soluble and non-biofriendly forms of fertiliser.

Graham Shepherd of BioAgriNomics is a soil scientist and farm consultant and author of the widely commended Visual Soil Assessment method. See:


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