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What will climate change mean for SA agriculture?

2018-08-17 01:40

What are the small shifts that mean big changes, particularly for agriculture, in a changing climate? Mandi Smallhorne finds out.

Tshwane 2014. A meeting of commercial farmers from across South Africa. A middle-aged man stands to ask a question.

He wears a two-toned shirt and khaki pants – he couldn’t look more farming-conservative if he’d worn shorts and had a comb tucked into his socks.

“Now what I want to know is, with this climate change, we are going to have to move where we farm things, and what has government done about contingency plans? I mean, we will be farming mielies and there’ll be no silos, no railway sidings, none of the infrastructure we need. What are they doing about that?”

Those who work the land have tended to be ahead of the curve on climate change.

They may not be able to quote the research or use the scientific terminology, but they are interested and anxious observers whose livelihoods rest on being able to note the changes in the rainfall, the temperatures, the seasonal movements of insects and birds, the small shifts that mean big changes.

What will climate change mean for South African agriculture? What changes can we expect in how we use our land?

“Areas of Southern Africa have already seen significant warming between 1960 and 2014,” says Dr Emma Archer, an expert in sustainable agriculture at the Council for Scientific and Industrial Research.

The increase is not evenly experienced across the country – the interior is heating up more than the coastal areas, and some of the heat is coming in the form of heatwaves (three days or more of over 30°C), or extreme heatwaves (three or more days of over 35°C – not unusual in recent years).

Heatwaves like these can directly damage crops, or reduce their yield.

Killer heat, which we humans endure by sitting in front of a fan or (if we’re lucky) in an air-conditioned space, can also affect livestock such as cattle and poultry.

Professors Robert Scholes, Mary Scholes and Mike Lucas point out in their book, Climate Change: Briefings from Southern Africa, that when heat drives animals into the shade for relief, they have less time to roam and feed, and so there’s less energy available to grow.

Heat stress is especially bad for dairy cows – milk production dips seriously. “Prolonged exposure to high temperatures, particularly without adequate water, leads to death,” they write.

Persistent high temperatures – heat that lasts for days and doesn’t cool down significantly at night – are especially hard on animals.

And on humans, too, of course – farmers need to consider simple measures to protect workers from the impacts of high daytime temperatures.

A South African pilot study published in 2010 on outdoor workers in the Upington area found that “workers reported a wide range of heat-related effects, including sunburn, sleeplessness, irritability and exhaustion, leading to difficulty in maintaining work levels and output during very hot weather”.

The potential for harm is serious: over 50 000 people, mostly outdoor workers such as sugar cane cutters, have died worldwide due to chronic kidney disease, which is believed to be caused by severe dehydration in hot climates.

In India, notes Professor Tord Kjellstrom, expert in occupational health and heat stress, outdoor workers in some areas have to stop for a four-hour siesta to avoid harm to their health.

Those who wish to farm – or use land for any other purpose that requires working outdoors, such as game farming, open cast mining and construction – will need to take that into account when considering land use in the central interior and west of the country.

PRECIOUS LIQUID

The Western Cape has found out the hard way how drought changes lives.

Water is our biggest constraint on food production – South Africa is a fairly dry country, with annual average rainfall at 509mm (globally it’s 990mm), but rainfall patterns are changing and the amount of surface water available is likely to reduce.

The Limpopo Climate Change Response Strategy notes that more drought periods lead to greater demands on groundwater for irrigation, while changes in rainfall upset the crop-production applecart: too little rain, rain at the wrong time or huge floods of rain can all have devastating impacts.

At the COP17 climate change conference in eThekwini in 2011, farmers from across Africa – Zambia, Kenya, Malawi, Limpopo – told of a new climate regime, with rains that come at the wrong time; too late for the traditional planting season; or too late and too much, bucketing down in floods that wash away seedlings and topsoil together.

Archer notes that, in certain areas, we in South Africa already seem to be experiencing shifts in rainfall seasons, with a possible drying of spring in the summer rainfall region that covers most of South Africa: that is, less rain in October, November and December.

And in the winter rainfall area, essentially the Western Cape, it’s likely less rain can be expected.

But never mind, we’ve got that groundwater to fall back on, right? We can just drill, baby, drill, into those lovely aquifers under our feet.

Not so fast, warns Dr Emmanuel Mwendera, research team manager at the Agricultural Research Council’s (ARC’s) Institute for Soil, Water and Climate: “Groundwater is a safety valve when surface water is not available, but it’s a finite resource, so we cannot extract it indefinitely.”

We must harvest underground water sustainably or face the fate of many Chinese wheat farmers, now drilling 300 metres down for water, or North Gujarat in India, where the water table drops by 6m a year.

“Where there is cheap pumping technology and everyone has access, groundwater reservoirs are being depleted completely,” says Mwendera, which is why it’s crucial that the state understands just how much groundwater we have, and efficiently monitors and regulates the extraction of it.

And remember, those underground aquifers need to be refilled or, as water experts put it, recharged – and when surface water resources (rain and rivers) are reduced, the rate of recharge is going to be lower.

Groundwater is insurance, but we should draw on it as little as possible, so that it’s there when we really need it.

PLAGUES AND PESTS

Minor factors in play already include insects, alien plants and microbes.

Remember those stories last year about the devastation wreaked by the fall armyworm on staple crops across sub-Saharan Africa?

The pest explodes after droughts, so scientists like Professor Kenneth Wilson of Lancaster University think that “intensifying droughts brought on by climate change” may have been behind the insect plague.

The changing climate opens up new niches for both insects that prey on crops and microbes that prey on humans (malaria, for example, is expected to move south and east in sub-Saharan Africa).

Likewise invasive alien plants. In a presentation, Dr Roger Price of ARC pointed out that aliens (which can take over agricultural land, choke rivers and dams, and increase fire risk) thrive on disrupted land; where indigenous plants have died out due to an inhospitable climate, they will move in fast.

Many of our worst invaders are from subtropical climes, so warmer weather will be better for them.

Plants like pompom weed and Satansbos are extremely difficult to get rid of, and may make land difficult to farm.

Some aliens are useful, of course – pines and eucalyptus are cultivated for timber and paper. But plantation forestry is very vulnerable to increased fire risk in the changing climate, so the industry is improving monitoring, developing more firebreaks, mixing species up a bit more and looking at speedier response times, says Archer.

ADAPT OR DIE

None of this means that successful farming will not happen in the future South Africa – but the successful farmer will be one ready to adapt to changing conditions.

Areas where certain crops are farmed will change, as shown in master’s student Oska Matji’s 2015 research report, with interesting maps illustrating just how much climate change may shrink our maize production area.

Where maize fields have traditionally covered much of North West and Free State provinces, as we move into the immediate and long-term future, the range shrivels like a drying puddle and shifts eastwards, so that the Eastern Cape and southern KwaZulu-Natal become important maize-producing regions, while Free State and North West contract dramatically.

Which could mean better infrastructure (like roads) and more jobs for the job-hungry Eastern Cape – but could also threaten some important reserves that are havens for wildlife and indigenous plants.

To be a successful farmer in the present and future, says Archer, you need to be ahead of these changes, to be “highly adaptive and listen to the land, and many farmers are very good at that.

For both crops and livestock, what we already know is that more diverse production systems seem to do better.”

Monoculture – one crop like maize, or one kind of livestock, even one kind of forestry tree – does very well until a hard year, a drought, a pest, a microbe comes along, which wipes out entire production systems.

Diversifying makes farms “much more resilient, much more adaptive,” she says.

In addition, there’s a lot of know-how and inexpensive technology that can be harnessed to support sustainable farming – Archer tells of a dairy farm near Polokwane using architectural and smart design features like wind-driven cooling vents and other tactics to cool the dairy cows.

We have a picture in our urban heads of what a successful farm looks like, she says, “but it’s not necessarily appropriate to what our climate change future looks like”, this despite the fact that our scientists and farmers have known for quite some time what is appropriate to semi-arid farming.

“We have to update our picture,” says Archer.

* This is the third in a series of articles on climate change and food security, made possible by the support of the African Academy of Sciences

This feature is part of a journalism partnership called Our Land, between City Press, Rapport, Landbouweekblad and Code for Africa, to find the untold stories, air the debates, amplify the muted voices, do the research and, along the way, find equitable solutions to SA’s all-important land issue.

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September 23 2018