Feeding the World

Two ways to grow more food

Thanet Earth opened in Kent in 2009 and is the largest greenhouse complex in the United Kingdom, covering a site of around 90 hectares. Tomatoes, peppers and cucumbers grow there without soil, their roots in an inert material fed with a nutrient solution, under computer-controlled temperature, humidity and supplementary lighting that extends the growing season well beyond what a British field would allow. Combined heat and power units on site generate electricity, and the waste heat and carbon dioxide from them are piped into the glasshouses rather than released. Rainwater is collected from the roofs. Several hundred people work there, and yields per square metre are many times those of the same crops grown outdoors. In Kibera, a dense settlement in Nairobi, families grow kale, spinach and onions in large sacks filled with soil and stones, planted through holes cut in the sides so that one sack produces from its top and its flanks at once. The method spread after violence in 2007 and 2008 disrupted food supplies into the settlement, and it works because it needs almost no land, uses vertical space where there is no horizontal space, and can be watered with household waste water. A household eats better and sells the surplus. Both are answers to the same question. They are not, however, comparable on a single measure, and that is the whole difficulty of this topic. Thanet Earth produces vastly more food; the sack gardens reach people that no glasshouse in Kent will ever feed. Three questions make the comparison work: how much does it yield, what does it cost the environment, and who ends up eating better. This module works through the strategies, large-scale and sustainable, and then weighs them that way.

Five food supply terms

The first three are large-scale approaches, the fourth is the sustainable philosophy behind several others, and the fifth is the one that sounds simple and is not.

Order the Green Revolution

These six stages describe how a large-scale strategy raised output and accumulated costs. Put them in order.

• Plant breeders develop varieties of wheat and rice that yield far more per plant
• Those varieties are planted with fertiliser, pesticides and reliable irrigation, which they require to perform
• Harvests rise sharply and countries that had imported grain begin to feed themselves
• Farming becomes dependent on bought inputs that have to be paid for every season
• Groundwater is drawn down and soils are damaged by continuous cropping and heavy chemical use
• The gains concentrate among farmers who could already afford the seed, the fertiliser and the pump

Why can local food cost more carbon?

Tomatoes grown in a heated British glasshouse can carry a larger carbon footprint than tomatoes shipped from Spain. Which answer explains that?

• Transport is usually a small fraction of the energy involved in getting a crop from field to plate, so the distance travelled is a poor proxy for the emissions produced. A crop grown out of season in a cool climate needs heat and artificial light for months, and that energy can easily exceed the fuel used to move the same crop from a country where it grows outdoors in sunshine. The number of miles measures how far the food came and not how much energy went into it, which is why the two questions have to be asked separately.
• Ships and lorries do not actually produce many emissions.
• Imported tomatoes are of lower quality, so more are thrown away.
• Imported food always has a lower footprint than local food.

The menu, and the two examples weighed

The specification note asks for large-scale and sustainable approaches to be weighed on real trade-offs through the named examples, so the first two columns are the strategies and the third puts the two case studies side by side.

Match each method to its trade-off

Three questions, then a verdict

The specification note asks you to weigh large-scale approaches against sustainable and local ones on genuine trade-offs, using the named examples. The weak answer describes both and concludes that a balance is needed, which is true of almost everything and therefore says nothing. Put three questions to every strategy and the comparison builds itself. How much does it produce? What does it take from the environment? Whose plate does the food reach? Those three rarely point the same way, and the disagreement between them is the argument you are being asked to make. A method can win decisively on the first and lose on the third, and noticing that is the judgement. Then name the measure you are deciding by, because otherwise a conclusion is only a preference. Deciding by total output, intensive methods win and it is not close. Deciding by what the soil and the water table look like in fifty years, they do not. Deciding by whether a family in a dense settlement with no land can eat better this month, a sack of earth outside the door beats a glasshouse in Kent, however much the glasshouse grows. One warning about a phrase that sounds like an argument and is not. Counting the distance food has travelled is not the same as counting what it cost to produce, and a crop raised out of season under artificial heat and light in a cool country can carry more emissions than the same crop brought from somewhere it grows in the open. Use the idea if you like, and say what it does and does not measure, because an answer that treats a short journey as automatically greener has assumed the thing it needed to show.

Complete the food strategy facts

Thanet Earth in Kent opened in _____ and covers a site of around 90 hectares, growing tomatoes, peppers and cucumbers by _____, which means their roots sit in an inert medium fed with a nutrient solution rather than in soil. In Kibera in Nairobi, households grow kale and spinach in _____ filled with earth and planted through holes in the sides, a method that spread after food supplies were disrupted in 2007 and 2008. The spread of high-yielding wheat and rice varieties from the 1960s, known as the _____ Revolution, raised harvests dramatically and left farming dependent on inputs that must be purchased every season. Roughly a _____ of all food produced worldwide is lost or thrown away before anybody eats it.

Spot the three sound statements

Select the THREE statements that could stand as they are in an answer.

• A large commercial glasshouse and a household sack garden are answering different questions, so a conclusion has to say which measure it is judging by rather than declaring one of them better in general.
• The distance a crop has travelled tells you nothing on its own about the energy used to grow it, so a short supply chain is not automatically the lower-emission option.
• Reducing waste is unusual among these strategies in having no real drawback, given that roughly a third of food produced worldwide never reaches anyone.
• Organic and permaculture methods produce more per hectare than intensive farming as well as protecting the soil.
• The Green Revolution raised yields without any significant costs attached.
• Urban sack gardening could replace commercial agriculture as a country's main food supply.

A 9-mark comparison, marked

"Large-scale strategies are more effective than sustainable local ones at increasing food supply." Using named examples, assess this view. [9 marks] Thanet Earth, opened in Kent in 2009, is the largest greenhouse complex in the United Kingdom and covers a site of around 90 hectares. Growing tomatoes, peppers and cucumbers hydroponically under controlled temperature, humidity and supplementary light, it achieves output per square metre many times that of field cultivation and supplies supermarkets nationally, employing several hundred people. On sheer quantity produced, nothing local or small-scale approaches it, and its designers have addressed some of the environmental cost directly by generating power on site and piping the waste heat and carbon dioxide into the glasshouses and by harvesting rainwater from the roofs. Against that, holding a growing climate against a British winter consumes a great deal of energy whatever is recovered, which is why the food miles argument for it is weaker than it first appears: the crop travels a shorter distance and the production uses more power, and those are separate quantities. The sack gardens of Kibera in Nairobi, which spread after supplies into the settlement were disrupted in 2007 and 2008, produce a trivial quantity by comparison, a few kilograms of kale and spinach from a sack outside a door. Their advantage lies elsewhere. They need almost no land, which is what a dense settlement lacks; they use household waste water; they cost almost nothing to start; and the food reaches people whom commercial supply chains serve poorly, with the grower keeping what is grown and selling the surplus. I partly agree with the statement, and the answer depends on the measure. Judged on total output, large-scale strategies are more effective and the gap is enormous. Judged on environmental cost per unit of food, the case is far closer than it looks. Judged on whether a particular household eats better this season, an intensive development in Kent does nothing for a family in Nairobi, and a sack of soil does. The two are solving different problems and the sensible conclusion is that a food system needs both rather than a winner. What earned the marks: both named examples used with dates and specifics rather than mentioned; the environmental defence of the large-scale example given before it was criticised; the food miles point handled as a genuine complication rather than a slogan; and a conclusion that judges on three stated measures and explains why the comparison is not a contest.

Find the two that weigh a trade-off

Five sentences about food strategies. Three of them state only an advantage or only a drawback. Tap the TWO that set one against the other.

• The glasshouses recover their own heat and carbon dioxide and collect rainwater, and holding a growing climate against a British winter still consumes a great deal of power.
• Hydroponic growing produces far higher yields per square metre than field cultivation.
• High-yielding varieties transformed harvests across whole regions while tying farmers to fertiliser and seed that must be bought again every season.
• Organic farming protects soil structure and biodiversity.
• Waste accumulates on the sea bed beneath fish pens.

Build the food miles sentence

Assemble a sentence that uses the idea without overstating it.

Four decisions about food

Each choice is real, and each trades one of the three questions against another.

• A dense urban settlement has almost no cultivable ground, an unreliable supply chain and households with very little money. You are asked what would help most.
• An irrigated farming region is producing well, and the water table beneath it has fallen every year for two decades.
• A supermarket proposes labelling produce by the distance it has travelled, presenting shorter journeys as the greener choice.
• A government wants one intervention that raises effective food supply without new land, new water or new energy.

Weigh the two approaches

Using named examples, assess whether large-scale or sustainable local strategies are the better way to increase food supply. [9 marks]

• Dates and specific details show the examiner these are real case studies
• The three measures: output, environmental cost and who the food reaches, which rarely agree
• A two-way point: an on-site energy measure that reduces a cost it also creates
• The two approaches may be solving different problems