Migration adaptations to water scarcity

It must be recognised that sometimes, the smart choice is to retreat, rather than fighting against the odds. In Africa and Sub-Saharan Africa, rural out-migration has been a trend for decades, as families send members to cities in search of work and supplementary income. Other families have moved entirely, because of expectations of better prospects and livelihoods.

Previously, migration has been driven more by war and economic hardship, but in the face of climate change and increasing difficulty in growing crops, many security-minded academics, think tanks, and countries expect climate migrants, or even climate refugees to increase in number. These migrations will occur not only in Africa, but in India and Africa, contributing to geopolitical, economic and cultural tensions.

In Ghana and Nigeria, there is moderate evidence that crop losses in bad weather encourages out-migration of rural farmers, as compared to rural families not engaged primarily in farming. Migration does not have to be rural-urban either; some farmers in Ghana have chosen to move to wetter areas in the south of their country to re-establish their livelihoods as farmers.

Of course, migration is never easy or cheap. In the Ghanaian and Nigerian cases, migration is often a considered after less costly and risky farming adaptations have already been tried, such as diversification of income.

The same study is extremely interesting to me, because it cited another study which highlights a paradox. Ironically, the poorest families who suffer the most from crop failures and water scarcity cannot afford to migrate or send any person out to work. Migration is undertaken by relatively better-off families, while the poorest are stuck in a poverty trap. Climate change induced crop failures will understandably reduce the wealth and capital of families, putting more poor farmers into this poverty trap.

How does migration fare as an option in the eyes of aid organisations or national policy? Collier and Dercon in a recent review of the African smallholder farming situation briefly mention that migration is a viable solution to helping smallholders, but is ill supported policy wise. Other adaptations are much better promoted and supported in Africa to combat poverty, meaning that migrants take on all costs and risks by themselves.

One reason I can offer for this is that migration is not an end, but a means. A policy that promotes migration for its own sake cannot solve the problems of poverty, but merely transplant problems elsewhere into already congested urban areas. I imagine that this is not a scenario that policy makers want to play out.

I think this short post about migration as an adaptation to water scarcity rounds up the adaptations to water scarcity series nicely. While migration does not technically combat water scarcity, it managed to avoid the problem. Sometimes it also is the most sensible and least-painful option for poor and water-stressed farmers.

Stay starchy,

Mr. Cassava

Crop adaptations to water scarcity

In the previous posts I spoke about farming adaptations, but now I'll be writing about how farmers select crops to grow.

The environmental preferences of crops can be also complex. For example, tomatoes grow well in hot climates, but require a lot of water. In Africa, farmers need crops that tolerate hot and dry conditions. But at the same time, they also need crops that respond well to unpredictable precipitation timings and amounts.

For example, the cassava plant reduces leaf formation and growth under water stress rather than induces leaf-fall, helping it recover and begin growth if the water shortage ends. This makes the plant comparatively more efficient than others in surviving under stress conditions. It was also found that different cultivars of cassava performed differently in response to the water stress, with one cultivar recovering so well that it performed as well as the control plot after the stimulated drought.

The cassava or tapioca is a starchy, high calorie crop which is an important in the diet of many urban dwellers as well, and has many industrial uses. A study conducted in Nigeria found that cassava has potential to employ large numbers of people, due to high industrial demand. This means that the crop is also useful as a crop that can be sold to urban markets, something like a dual cash-subsistence crop! I imagine that this advantage could be useful in specific scenarios. If market prices are bad, a cash crop growing family may suffer more than a subsistence crop growing family, which can survive on their own harvest.

Other important staple food crops that grow well in the driest areas are sorghum, millets, groundnuts and beans. Traditionally, millets were also important crops in the Americas, but in modern times, widespread irrigation and application of water has enabled commercial scale growing of corn and wheat instead. Personally, I imagine that certain crops are grown and consumed more than others because of preference or cultural tradition, and not because of cost/water-efficiency. However water shortages in the arid areas of the United States have revived some interest in millets.

Other considerations

But of course, it is important to bear in mind that chasing water-efficiency is merely one solution, born out of looking at the agriculture problem in one way. The ultimate goal of farming is not to "be water-efficient". Being water-efficient is a means to an end. Profit, quantity, quality and perhaps risk-minimalisation are goals that actually make more sense and incentivise farmers. A study in northern Germany brought to my attention the idea that farmers choose risk-efficient strategies in the face of water quotas or price hikes.

We have to keep in mind that the choice of crop sown and grown by farmers is influenced by many other factors. For example, easy access to markets makes cash crops viable to grow, but many rural farmers have to grow crops for subsistence, and cannot sell surplus crops due to lack of market access.

Role of crops

Understanding how certain crops are more water efficient than others could potentially inform policy on development or water resource management. For example, in the absence of regulation on water use, or in cases where charging for water is not possible, local governments could instead tax water-inefficient crops to discourage production. 

Or perhaps, governments and aid organisations could distribute more drought-resistant crops and cultivars to rural farmers. Farmers in Africa have already adapted to water shortages are grow many hardy, water-sipping crops, but this information could be relevant to farmers in other countries hit by climate change/water stress.

More research needed?

While this post talks about water efficient crops as an adaptation strategy to climate change, this is very much a widely adopted adaptation already, and nothing new to Africans. Neither does this post does not offer details about which crop is the most efficient. I have found studies determining the water efficiency for biofuel production, but biofuel energy is rather different from consumable energy. If anyone has some information on this, I would like to hear about it in the comments below!

Thanks guys, and Stay starchy,

Mr. Cassava

Farming adaptations to water scarcity

Agriculture in arid areas faces natural barriers; that is a lack of water or nutrients in degraded soil. Without understating the importance of the latter, my next few posts will be a short series on adaptations to water scarcity made by farmers

In arid areas, not only is water lacking, but water use efficiency is also poorer. For example, rangelands in arid South Africa generally produce very little biomass per unit of water input, especially degraded lands. High evaporative demand in the dry and hot climate means that farmers are able to grow less with any particular amount of water. Stroosnijder et al. (2012) estimate that in common situations, non-productive losses of water can be as high as 85%.

This may necessitate farming adaptations, crop choice adaptations, or may drive abandonment of farming and/or diversification of income sources to non-farm labour.


Farming adaptations

Through various techniques which are based on various mechanisms, farmers can compensate for lack of water. In the years of the Green Revolution and after, use of large scale water diversion and storage projects spread from the developed west to other places across the world. Abstraction and transportation of "blue-water" resources from places of surplus to places of drought

However, smaller scale innovations can also play a significant role by changing the amount of evaporative loss of their farmland, or drawing water from other zones of the subsurface.

A few examples of farming adaptations that I'm refer to are no-tillage of fields to sow seeds and the spreading of crop residues atop soils as "mulch" to reduce evaporation losses. Mulching is considered and effective way to reduce soil evaporation in both semi-humid and arid climates, and is thus widely used to increase moisture content below soil surfaces. A mulch layer not only shades soil and slows evaporation, but prevents water from being drawn directly to the surface through capillary action. This means that evaporation potential is decreased

Cover crops, or crops that help soils retain water or draw water from deeper layers may also be planted in mixed fields. In Senegal, experiments have indicated that shrubs with deeper root systems are able to hydraulically 'lift' water for shallow rooted food crops to use.

Farmers in Ghana for example, have been found to diversify to non-farming activities or animal raising, especially in the poorest and driest areas. Other practices adopted include changing planting and harvesting dates as necessary.

Corbeels et al. (2014) also argued that while water saving adaptations have had mixed results, micro-scale rainwater harvesting projects can make a significant difference in crop yields for farms reliant on rainwater.

Better education of farmers can help farmers adapt the ways they use existing tools and resources. Reindeers et al. (2013) highlight how irrigation efficiency has to be addressed on a multi-scalar framework. from source and transport, to farm and application. For instance, the timing, rate, and amount of water used for irrigation is important, as only a certain amount of water is "beneficial" (absorb-able by plants). Farmers performing simple adaptations such as irrigation at night can increase water use efficiency by reducing evaporation. Drip irrigation techniques that supply small amounts of water constantly to the soil have also been shown to increase water use efficiency significantly.


Where and when are these small scale innovations important? 

In poorer places? In places of high population density relative to land carrying capacity? In places lacking infrastructure and networks of marketing and farming? One way to look at this question is to evaluate the actual usefulness and implementation of farming adaptations


Evaluating farming adaptations

One should note that the farming adaptations mentioned above are not hippie, experimental, nor overly optimistic solutions. For instance, no-till farming is widely used in arid areas of the Americas. 

Why is it then, that many studies (1) (2), have reported poor or less-than-good rates of uptake of irrigation and other small scale adaptations? The answer given by many of those studies point to both upfront costs and opportunity costs. Upfront costs are simple to understand, as farmers find it difficult to raise capital or borrow money to invest in new technology or seed/fertiliser inputs. Understanding opportunity costs however, has also been crucial in informing us about the decisions made by small scale African farms.

Often, academics underestimate the value of labour and time for small farmers. This is crucial, because while small farmers do not have the resources to hire help, many new adaptations require more work on the part of farmers, such as spreading of mulch. In fact, African smallholders prioritise their labour hours well and are highly efficient. Efforts that prove to be inefficient or unprofitable will not be taken up.

The value of seemingly insignificant items, like crop residue also plays a part in decision making. Crop residue has value in the form of livestock feed, and this opportunity has to forgone when used for mulch. Farms with livestock, or villages that share a communal livestock pool with everyone contributing to that pool are thus less likely to use practices such as mulching when feed prices are high. Corbeels et al. (2014) make the important point that adaptations take time to implement and yield results, resulting in a period of no income. The period of perceived income loss causes many farmers to abandon their trial plots. And at the end, they argue that adaptations can force trade-offs that result in no increase in net-income.

Finally, it should be obvious that not all strategies can be easily applied in every circumstance. studies find that no-tillage can only be considered efficient and profitable when used properly in suitable circumstances. Orr (2003) and Orr and Richie (2004) show convincingly that seemingly big problems like pest management can sometimes be small compared to bigger controls on yields such as soil fertility. It would be worrisome if the same issues of over-focusing exist in the water arena.

The good news is that small-scale or in-situ application of rainwater harvesting is more widespread than large scale dam and reservoir projects. Many of the presently commonly applied adaptations are traditional, or adapted from traditional practices but newer small-scale or in-situ adaptations can further increase crop yields by up to 50%. Farms which have had little adaptations, and have relied the most on natural rainfall have the most to benefit.


Conclusions

I believe that farming adaptations are essential to increasing productivity on marginal crop producing areas and increasing farmers' resilience to bad weather. However, given the nature of tradeoffs involved, introduction of adaptations made in the presence of solid education and advice, to avoid dashing the hopes of farmers.


Here's wishing readers a Happy New Year this 2016. Until next time.
Mr. Cassava