Friday, January 8, 2016

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


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