Urban Food Chains

the links between diet and power

cultivation green beans plants
What “by numbers” is about
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Across this website, readers will have seen posts such as butter by numbers or cheese by numbers. The purpose is not spelt out in these posts, so here is the thinking behind the “by numbers” coverage.

First, most of the figures cited go back to the end of the 20th century and are volume measurements. The choice of tonnages over the more usual measurement of currency is intended to give an idea of the additional capacity that imports generate for their economies.

In its simplest terms, importing food occupies production capacity the exporting country cannot use for the local economy. For countries like New Zealand, rural populations are so sparse and urban populations are so far apart that this is  not a problem.

Market gardeners close to urban centres in countries such as Kenya, on the other hand, can find themselves left with crops of green beans for which they have no local outlet. Having promised to grow premium vegetables for affluent industrial economies, there is no wriggle room for producers if  retail customers change their minds.

By looking at tonnages, it becomes possible to calculate the agricultural resources that are occupied by export production.

The use of data going back to the late 1990s is a reflection of the fact that multiple retailers invested heavily in electronic point of sale and data management for food sales during the early 1990s. The later years of the 1990s mark the moment that the results started to become visible.

cultivation olives
Dietary gold on trees
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pic Wikimedia Commons

Today (Friday November 26) is World Olive Tree Day, as growers in the northern hemisphere prepare to pick the next crop of olives. More than two thirds of the world’s olive trees grow in the Mediterranean basin and survive thanks to their deep roots. Younger trees planted in more recent groves will often be irrigated until their roots have reached cooler, damp rock formations.

Olive oil ranges in colour from green to gold.

Olives are a winter crop: starting in November unripe green olives are gathered and pressed for distinctively strong, green oil. As the winter progresses, the olives darken and ripen, the oil changing to gold as the flavour softens with the fruit. The harvest continues into February and March, depending on varieties and locations.

Traditional olive-picking techniques needed the olives to be hard enough not to break up as pickers beat the trees with heavy sticks. Today, large groves are harvested with a mechanical arm attached to the trunk of the tree. The tree is then shaken vigorously, emptying the fruit onto large sheets spread out to catch the crop. The process is stressful for the tree, but is quicker than the stick-wielding villagers. The remaining winter months are a time of recovery.

Once picked, olives are fragile. Away from the tree, the olives start to accumulate free oleic acid as they oxidise during the different stages of processing. Only when the oil is extracted and stored under nitrogen can the oxidation be halted. The largest pressing plants, typically in Spain, where batches are consolidated and have more time to oxidise, face the prospect of minimising the effects as best they can.

Olives picked for the table have an additional constraint: unlike olives bound for pressing, every table olive needs to be visually perfect. To remove the stones from olives, the flesh needs to be firm and the olive must be unripe. To produce black pitted olives, green olives are treated to make the flesh black and then the stones can be removed mechanically. By the time an olive has fully ripened and turned black naturally, it is no longer possible to remove the stones mechanically, since the soft flesh just falls apart. The taste, however, is exquisite.

cultivation livestock plants
Settling down
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Reading the preface of James C Scott’s book Against the Grain, I realised that it promises to live up to my expectations. Scott disentangles the timelines of settled agriculture, which is only possible with domesticated crops and livestock. The process of domestication was spread over millenia in the region between the Tigris and the Euphrates, starting around 8000BCE. Domestication was an essential step on the way to settling in a fixed location.

Establishing crop-fields attracted species that were later domesticated.

Establishing permanent crop-fields attracted wildlife such as ducks and other fowl that could, like fire or food crops, also be domesticated. Scott argues that the process of domestication is reciprocal, since humans adapted in subtle ways to the livestock they wanted to keep.

There is a lot of detail to absorb, so it will be a while before I return to discussing his analysis of the history of the region that later became Mesopotamia and Sumeria. Scott is published by Yale University Press.