Irrigation: 11 thoughts on sustainable water use in agriculture

Rajendra Uprety, agriculture officer, ministry of agriculture development in Nepal, Choma, Zambia. @urajendra

If you want productivity and efficiency, put irrigation systems in the hands of farmers: Generally speaking big dam and irrigation systems in developing countries are less productive. When the control and management of such systems is not in the hand of farmers – the water users – it makes water reliability more vulnerable and less useful to farmers to intensify their cropping systems and adopt new technologies.

Richard Munang, Africa regional climate change coordinator, United Nations Environment Programme, Nairobi, Kenya. @MTingem

Irrigation cannot be understood in isolation: Irrigation policy must be considered alongside other elements including improved markets, institutional and legal transparency, research and development, and ecosystems management. I think what needs to be done is to ensure that water-use policies should be developed within a broader framework that promotes agricultural growth through profitable investment.

The answers lie in small-scale solutions: Rolling out large-scale irrigation schemes is not the answer. With high costs per hectare and per beneficiary, large schemes are costly and slow to develop, and relatively few benefit from improved production. Scenarios from the comprehensive assessment of water management in agriculture suggest that even doubling the irrigated area in sub-Saharan Africa would help provide only about 10% of the continent's food supply.

Caspar van Vark, freelance journalist specialising in farming and food security, London, UK. @foodpolicynews

We need to link irrigation and agricultural policy to public health: You can get unexpected consequences from changes to irrigation practices. For example, there are links between irrigation and malaria for example, because the design of irrigation can create breeding grounds for mosquitos. There needs to be an overlap between public health and agriculture policy to make sure that you don't give with one hand and take with the other.

In Africa there is great potential but we need a complex mix of solutions: In Africa agriculture is almost entirely rain fed and only about 6% of agricultural land irrigated. Most of that is in just a few countries such as Egypt and South Africa. The 2005 Commission for Africa report called for a doubling of the area of that irrigated arable land by 2015. This is possible because there is in fact enough water in Africa, but I think it needs a complex mix of solutions: large and small, and tailored to local conditions. You have to take into account a whole load of geographic, agronomic, and economic factors to make irrigation projects sustainable.

Anna Swaithes, head of water and food security policy, SABMiller plc, Kampala, Uganda. @sabmiller

We need to demonstrate the value of efficient irrigation methods to farmers: In Rajasthan, India we've addressed this using the same model as in the US, by working with small farms which are identified as 'model' farms. These farms serve to demonstrate the benefits and increased productivity (around 20%) that more efficient irrigation methods can deliver. Highlighting these models helps facilitate the sharing of best practice across rural communities and has resulted in significant water savings.

Education has an important part to play: If you install an affordable irrigation system, the temptation will be to use it all the time. These model farms have done a very good job of helping farmers better understand optimal water use and that over-irrigating actually leads to reduced productivity. Education needs to include measurement and monitoring so that farmers are able to take informed decisions about when to irrigate, how much to irrigate and when to fertilise.

Kate Brauman, postdoctoral research fellow, University of Minnesota Institute on the Environment, Minneapolis, USA. @KateBrauman

We should measure our water use in relation to the local context: I think the work done so far to measure and quantify water consumption in various products has been tremendous. However there is a lot more work to do in contextualising water use for different places. For example, how much water is available? And how else might that water be used? In many places, it may make a lot more sense for farmers to grow a commodity crop efficiently and then purchase staple foods.

Julien Hardelin, agricultural policy analyst, Organisation for Economic Cooperation and Development, Paris, France. @OECD

Groundwater is an important issue for the sustainability of irrigation: In several OECD as well as non-OECD countries, groundwater resources represent a significant share of total agricultural freshwater withdrawals (above 30%). A recent PNAS study has shown for instance that groundwater resource will not be sustainable in Kansas, unless groundwater withdrawals are significantly reduced in the next few years. Groundwater can serve as a kind of insurance securing water supply. This is especially important in the context of climate change, with possible increases in the frequency – and severity – of extreme water events such as droughts and floods.

Simon Chevalking, irrigation specialist, MetaMetat, Wageningen, Netherlands

Forget irrigation, we need to get back to basics: Rather than focusing on irrigation methods, my stance would be to take a step back and look again at the soil and seed – where it all begins. Solutions to truly conserving water are then plentiful. The first example of this is soil moisture conservation through mulching (covering the soil with organic or non-organic material), using composting, reducing intense direct sunlight through agro-forestry or regreening. The second example is deficit irrigation, which in simple terms is knowing at which stages of crop growth to apply water allowing water stress at times, but allowing sufficient for it to produce equal harvests.

Makarius Victor Mdemu, lecturer in natural resource management & assessment, Ardhi University, Dar es Salaam, Tanzania

Many questions still exist about using systems of rice intensification (SRI): There has been interest to try SRI – a methodogy aimed at increasing the yield of rice – in Tanzania. Although it is at an early stage there are still many questions about it. First, ecologically rice is a water loving crop so is resource intensive. Secondly, there are other factors need to be taken into account when implementing SRI so that farmers do not going to risk crop yield.

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