Comment: Nobody, least of all farmers, wants animals to be hungry - but is grass-only best? Dr Jacqueline Rowarth investigates.

Drought is affecting the country. Holiday makers have been able to enjoy warm temperatures and sunny barbecues, but towns and cities are already on restrictions for watering gardens and washing cars, particularly in the north and east of the North Island.

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The situation for farmers is different – it is animals and crops that are the focus.

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Farmers in some areas have access to irrigation, but most don't, and they are increasingly worried about when rain might come.

Milk production was 4 per cent down in December for the top half of the North Island.

The freezing works are at capacity as farms of all types reduce stock numbers.

Water is an issue for the whole of New Zealand, urban dwellers as well as those in rural districts.

New Zealand is fortunate to have large quantities of renewable fresh water, but it isn't always in the right place when it is needed.

The bulk of what we use generates power through hydro dams, and because the water is returned to the water resource system, it isn't counted as consumptive extraction. The OECD figure for New Zealand's consumptive use is 2 per cent.

Of that 2 per cent, the Ministry for the Environment indicates (the latest report is dated 2010) that approximately 40 per cent is used for one Southland power generation consent which discharges to the sea, 46 per cent is used for irrigation, 6 per cent is industrial, 5 per cent is drinking (domestic) and 2 per cent for stock.

More recent Government publications indicate that the amount of water available and used in New Zealand is not known precisely, but it is known that there has been an increase in irrigation consents.

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It is also known that domestic use of water is relatively high.

The average person uses 227 litres of water per day (86 flushing the loo, 68 washing the body, 36 washing clothes, 32 in the kitchen and 5 cleaning the house).

The basic need for humans has been calculated at 50 litres a day and in some countries less than 10 is available ... New Zealand is a lucky country.

While the debate on water use continues, farmers in drought need to feed animals.

Dr Jacqueline Rowarth. Photo / Supplied
Dr Jacqueline Rowarth. Photo / Supplied

In 2013 the FAO reported a 1 per cent increase in the global Food Price Index simply because of the drought in Oceania.

A record milk price followed and farmers who could feed their animals through the drought were able to capitalise.

As well as the increase in revenue (which more than compensated for the extra costs of feeding), animals were maintained in peak condition not sent to slaughter or dried-off, didn't need a long time to regain body condition, produced a calf as expected, and after a couple of months were able to be mated again.

Milking days, in-calf rate and longevity in the herd assist with keeping the greenhouse gas production (GHG) per kg of milk solids low.

Other benefits of supplementary feeding shown by research led by scientists in the UK are reduced methane, and reduced losses of nitrogen, phosphorus and soil per unit of production.

This has been confirmed in New Zealand by AgResearch, DairyNZ and Massey University researchers.

It is important to recognise that bought-in supplements might have an environmental impact where they were grown.

Listen to Rowena Duncum interview Dr Jacqueline Rowarth on The Country below:

The use of waste products such as vegetable or fruit, distillers' grains, or palm kernel expeller (when it has been certified as sustainably grown in plantations) overcomes some of the concerns, but transport GHG are generally created.

Feeding of supplements does increase the cost of production but increases the production per hectare. This gives increased return per hectare when the milk price is close to or above the long term average.

In turn, the increased income allows investment in infrastructure, including methods to feed supplement efficiently.

Although some commentators have suggested that farmers would be better off going back to "all grass" they have overlooked the fact that droughts, floods and unseasonably cold springs have wiped out grass several times in several regions across New Zealand in recent years.

Nobody, least of all farmers, wants animals to be hungry.

Future-proofing for urban and rural districts requires improved water management which will probably include better storage. In some areas the Regional Development Fund is supporting water management, but the effect is piecemeal.

A national programme is needed to enable coordination, efficiencies of scale, and encompass urban as well as rural requirements.

While the debate continues, supplementary feed has an important role in maintaining animal production and hence the export economy.

This in turn will help pay for the upgrades needed for water infrastructure across the country through tax and the money-go-round.

New Zealand ranks 11th in the world for water availability per capita; we should be managing our resource very much better than we are.

- Dr Jacqueline Rowarth is a soil scientist with a PhD in nutrient cycling. She has a 5 per cent share of a high input family dairy farm in the Waikato producing three times the district average in milk solids but only 60 per cent of the district average in nitrate leaching.