As we head into another drier-than-normal season, New Zealand needs to put more thought into water management

Urban rain and rural rain are different. The quality is the same - drops of water that, in New Zealand, fall out of the sky relatively pure - but interpretation of the quantity is very different.

Urban rain stops barbecues, dampens the washing on the line, and slows the traffic as though rain had never been experienced before. It interrupts activities for humans, but makes little difference to the ability of plants to grow, rivers to flow or dams to fill.

Rural rain does all three. Rural rain soaks into the ground. It reaches roots and allows the micro-organisms to function. When there is rain in sufficient quantity, primary production, and hence the export economy, flourishes.

This year some areas of New Zealand, including Auckland, have had rain. Some of the rain has enabled plants to grow in town and country (as well as stopping barbecues, wetting washing and slowing traffic), but many of the major agricultural areas have experienced only urban rain.

The weather maps frequently promise showers, and sometimes the predictions come true, but showers are not enough to make a difference to plants, rivers and dams.

A medium scale drought has been declared in Marlborough, Canterbury and parts of Otago bringing some assistance but no water. The Wairarapa and Waikato are being watched carefully – but declaration of drought doesn’t mean free rides for farmers.

Official declaration of drought means that money is given to the Rural Support Trust so that it can co-ordinate feed supplies across the country. In past years hay and straw, for instance, have been moved from areas where there is surplus to areas in need. This year, however, drought is relatively wide-spread and ‘surplus’ feed is in short supply. It is also increasing in cost.

Another funded activity for the Rural Support Trust is giving mental support by talking with people. Unfortunately, for many farmers engaged in taking care of their animals, including extra feeding out because the grass isn’t growing, ‘talking’ requires time that they don’t have.

In official drought, farmers can apply directly to the government for financial assistance. If successful in meeting the hardship criteria, they are given income equal to the unemployment benefit, but history indicates that not many of them qualify. The 2013 drought covered the whole of the North Island and the west coast of the South Island. The impact on the economy was estimated by MPI to be at least $1.3 billion, and it affected 20,000 farmers. Only 146 farmers qualified for rural assistance.

Another benefit is tax relief. The adverse event ‘income equalisation scheme’ allows farmers who experience adverse events to carry income from forced livestock sales over to the next income year. Tax is still paid, but there is flexibility in making the payments.

Banks also try to assist. Mortgage repayment can sometimes be added to capital to prevent a mortgagee sale and the problem that would cause for land values - if land values fall, more farmers would find themselves overleveraged and struggling with the banks as well as the elements.

All these measures are trying to support farmers, but real relief from drought would mean more water, hence the discussions around the country on water storage and management.  The debate hinges on the environment and economics. To pay for the water storage and irrigation system, farmers have to increase productivity with more animals and or more crops, both of which are associated with increased fertiliser use. Increased fertiliser use has been associated with leakage into rivers, and nobody wants to despoil the environment.

In addition, it is not yet clear whether the farmers who intensify to pay for water infrastructure actually make more money. Statements have been made recently that it might be more sustainable in the long run simply to destock during drought and operate a more extensive production system. Doing so would, however, have considerable impact on the overall economy because of loss of jobs that are currently associated with every stage of the farm to fork value chain.

In addition, some important components have been overlooked. One of these is the soil carbon which advocates have been promoting as an offset for Green House Gases with an eye to the Emissions Trading Scheme.

Soil organic matter, over half of which is carbon, builds up under irrigation when compared with no irrigation. This is because plants are able to continue to grow, and litter (dying leaves) and roots feed the soil organisms. As long as fertiliser and water are maintained, the soil organic matter will come to a dynaUrban rain and rural rain are different. The quality is the same - drops of water that, in New Zealand, fall out of the sky relatively pure - but interpretation of the quantity is very different.

Urban rain stops barbecues, dampens the washing on the line, and slows the traffic as though rain had never been experienced before. It interrupts activities for humans, but makes little difference to the ability of plants to grow, rivers to flow or dams to fill.

Rural rain does all three. Rural rain soaks into the ground. It reaches roots and allows the micro-organisms to function. When there is rain in sufficient quantity, primary production, and hence the export economy, flourishes.

This year some areas of New Zealand, including Auckland, have had rain. Some of the rain has enabled plants to grow in town and country (as well as stopping barbecues, wetting washing and slowing traffic), but many of the major agricultural areas have experienced only urban rain.

The weather maps frequently promise showers, and sometimes the predictions come true, but showers are not enough to make a difference to plants, rivers and dams.

A medium scale drought has been declared in Marlborough, Canterbury and parts of Otago bringing some assistance but no water. The Wairarapa and Waikato are being watched carefully – but declaration of drought doesn’t mean free rides for farmers.

Official declaration of drought means that money is given to the Rural Support Trust so that it can co-ordinate feed supplies across the country. In past years hay and straw, for instance, have been moved from areas where there is surplus to areas in need. This year, however, drought is relatively wide-spread and ‘surplus’ feed is in short supply. It is also increasing in cost.

Another funded activity for the Rural Support Trust is giving mental support by talking with people. Unfortunately, for many farmers engaged in taking care of their animals, including extra feeding out because the grass isn’t growing, ‘talking’ requires time that they don’t have.

In official drought, farmers can apply directly to the government for financial assistance. If successful in meeting the hardship criteria, they are given income equal to the unemployment benefit, but history indicates that not many of them qualify. The 2013 drought covered the whole of the North Island and the west coast of the South Island. The impact on the economy was estimated by MPI to be at least $1.3 billion, and it affected 20,000 farmers. Only 146 farmers qualified for rural assistance.

Another benefit is Tax relief. The adverse event ‘income equalisation scheme’ allows farmers who experience adverse events to carry income from forced livestock sales over to the next income year. Tax is still paid, but there is flexibility in making the payments.

Banks also try to assist. Mortgage repayment can sometimes be added to capital to prevent a mortgagee sale and the problem that would cause for land values - if land values fall, more farmers would find themselves overleveraged and struggling with the banks as well as the elements.

All these measures are trying to support farmers, but real relief from drought would mean more water, hence the discussions around the country on water storage and management.  The debate hinges on the environment and economics. To pay for the water storage and irrigation system, farmers have to increase productivity with more animals and or more crops, both of which are associated with increased fertiliser use. Increased fertiliser use has been associated with leakage into rivers, and nobody wants to despoil the environment.

In addition, it is not yet clear whether the farmers who intensify to pay for water infrastructure actually make more money. Statements have been made recently that it might be more sustainable in the long run simply to destock during drought and operate a mic equilibrium with input and output. If fertiliser and irrigation is removed, the organic matter decreases again over time to reach a different dynamic equilibrium.

If drought occurs in a region which previously received rain, the organic matter will decrease as the soil organisms can work for longer in the soil than plants can grow on top of it. Deserts are the obvious examples of what happens.

Another huge and perhaps incalculable benefit is in farmer welfare.

Irrigation means more work than if rains fall, because irrigators have to be monitored and maintained, but irrigation gives confidence that plants will grow and animals can be fed (or crops harvested).

Farmer resilience is improved because some risk in production is reduced.

New Zealand has considerable quantities of fresh water and questions are being asked about whether or not we are using those resources efficiently. The OECD calculates that New Zealand has a total of 485 billion cubic meters of renewable freshwater resources, but uses only 1-2% of its water resources (OECD figures suggest 1.1% and World Bank estimates 1.5%) and agriculture is using approximately only 1% (FAO-UN figure).

The World Economic Forum Insight Report Global Risks 2015 puts Water Crises as first in the top ten risks in terms of impact, ahead of spread of infectious diseases, weapons of mass destruction, interstate conflict and energy price shock. Water crises didn’t enter the ranks until 2012… and now it is number one in the thinking. Water crises also rate eighth in terms of likelihood (after interstate conflict, extreme weather events, failure of national governance and various catastrophes).

Climate predictions from the National Institute of Water and Atmospheric Research (NIWA) for the next few months are that it will be normal to warmer than usual, and rainfall in some areas like Canterbury might be approximately average to slightly above average – but in most areas will be average to below average.

This means that overall, soil moisture and river flow will stay below average, dams won’t fill and soil organic matter will decrease.

As a developed country it behoves New Zealand to be thinking sensibly about water management for the future. Employment, environmental sustainability and economic viability depend upon it. And if NZ doesn't take the lead for itself, some other country might decide to do it for us...



Comments (2)

by Viv Kerr on March 05, 2015
Viv Kerr

You are suggesting that irrigation is beneficial because it encourages carbon sequestration, in the form of soil carbon. This argument does not hold water unless you can demonstrate that the amount of carbon sequestrated in the soil outweighs the CO2 emissions of the dairy industry.

The dairy industry irrigates land to grow grass to feed cows who make milk. Fonterra's milk tankers then release large amounts of CO2 as they drive 81 million kms a year, to collect the milk. Then Fonterra releases massive amounts of CO2 as it uses 5,500 gigawatt hours a year of mostly fossil fuel energy to take the water back out of the milk. This is not sensible use of either fossil fuels or water.

by Don Graves on March 11, 2015
Don Graves

Greetings everyone, Nga mihi nui

Thank you for an opportunity to make comments !  :)

Jaqueline, ... your comments on the benefits of irrigation for "soil organic matter, over half of which is carbon, builds up under irrigation when compared with no irrigation. This is because plants are able to continue to grow, and litter (dying leaves) and roots feed the soil organisms. As long as fertiliser and water are maintained, the soil organic matter will come to a dyna..."

I'm not an expert on nutrient cycling or soil organic matter (SOM), however isn't your (truncated) comment conditional on the soil N:C ratio?, i.e. excess soil Nitrogen levels allow soil bacteria to rapidly decompose fresh sources of soil Carbon (leaf litter, roots, dead soil microbes & animal manures), as well as degrading longer lasting soil Carbon (humus)

As I understand these matters, during warm growing conditions of spring & summer, soil organic matter levels are likely to decrease under irrigated dairy pastures as a result of high ratios of N:C. ...

  • I await more informed feedback & opinion.

On other matters discussed above ....

"Another huge and perhaps incalculable benefit is in farmer welfare.

Irrigation means more work than if rains fall, because irrigators have to be monitored and maintained, but irrigation gives confidence that plants will grow and animals can be fed (or crops harvested).

Farmer resilience is improved because some risk in production is reduced."

This generalization is most applicable to irrigation of pastures & arable crops. Likewise, young woody plants with shallow roots need access to irrigation & benefit from weed control to decrease competition for scarce surface soil water resources.

However, the same cannot be said about crop production 'resilience' of grape growers (or orchardists) who regularly irrigate mature woody plants and thereby encourage the growth of surface feeding roots that in turn become dependent upon continued grower access to irrigation water.

Mature vines & trees that are capable of producing deep roots are able to continuously access reservoirs of sub-surface soil water, thus increasing crop & grower resilience during periods of extreme or extended drought when it is improbable that access to irrigation water resources will be available to use. 

Most gardeners are aware of the need to 'harden off' nursery seedlings before transplanting into field soils.  Most grape growers are wisely risk averse to losing their large financial investments to establish a commercial vineyard. However just because growers may have an ability to irrigate young establishing plants, doesn't mean that they should continue to irrigate mature vines at an increased risk of increasing dependence on access to water resources that may or may not be available. 

Climate change is here, how we adapt to the unpredictability of access to irrigation or rain water resources will determine how resilient our growers & crops are in the future. Due to environmental constraints on the availability of water elsewhere than here in NZ, there are parts of Europe where it is illegal to irrigate grape vines.  Our country has been 'blessed' with the good fortune to have luxury access to irrigation water resources, but in changing times we need to look for guidance from our overseas competitors who have a heritage of using more drought resilient management of these crops.

Just because we can irrigate, doesn't always mean we should irrigate. If we want more drought resilient grape crops we need to 'harden up', (take a concrete pill), encourage deeper plant roots, & discourage 'soft' surface feeding plant roots.

Increased levels of soil organic matter assists water-stable soil structure, reduces soil compaction, increases soil water-holding capacity & water infiltration ability & improves soil aeration. If we need local alternative solutions to current management practices we could look to feedback from North Canterbury grape growers in the "Greening Waipara Project" http://bioprotection.org.nz/research/programme/greening-waipara  ... supported by Lincoln Uni Agro-ecology & Lincoln Landcare research into growing biologically diverse ground-cover plants to replace prevalent herbicide  strips, thereby feeding soil OM levels & providing bio-protection against grape pests. 

Further alternative solutions to improving soil OM levels are now being demonstrated by grape industry innovator Peter Yealands, using charcoal ('biochar') made from vine prunings & mixed with compost, then returned to under-vine soils. Future research into improving soil OM levels & retaining mobile nutrients in pastoral & arable production systems could also include the application of biochar into root zones.

 



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