雅思阅读 156: Farming Without Soil（无土栽培）

改编自 TAPS / vertical farming reviews（2026年）。雅思阅读 Section 3 难度，约 1050 词。 素材来源：https://trendsaps.com/articles/5-0-5-0-110-117.pdf

Reading Passage

A. To a gardener raised on the smell of turned earth, the idea that a tomato plant does not actually need soil can feel like a trick. Yet strip away the romance and soil turns out to do two rather ordinary jobs: it holds the plant upright, and it stores the dissolved minerals that roots drink. Take those two functions away and replace them, and the soil itself becomes optional. That is the premise of hydroponics, a method in which crops grow not in earth but with their roots bathed in, or misted by, a fortified solution of water and carefully measured nutrients. The gardener, in effect, becomes an engineer. Because the exact mix of nitrogen, potassium and other salts is known and controlled, the plant is never left waiting for a nutrient to dissolve in a patchy field. Proponents argue that the result is faster growth, denser leaf and a harvest delivered on demand rather than on the weather's timetable. Strip away the wonder, though, and the method rests on a single insight: a plant only ever eats what has dissolved in water. The soil was never the food.

B. The reason the idea has suddenly attracted serious investment is water. Conventional agriculture consumes somewhere between seventy and eighty per cent of the fresh water that humanity withdraws, and a great deal of that is wasted. Rain falls on open soil, evaporates under sun, runs off downhill, or seeps below the reach of roots before a crop can use it. A closed-loop hydroponic installation attacks that waste directly. Water that the plants do not absorb is collected, filtered, re-balanced and sent back through the roots again, rather than being lost to the field. Producers report that well-managed systems use eighty to ninety per cent less water than open irrigation. The difference is not abstract: for a kilogram of lettuce, a field might demand fifteen to twenty litres, whereas a recirculating system can deliver the same weight on two or three. In a world where droughts no longer respect national boundaries, that ratio — nine litres saved for every one consumed — is what turns a curiosity into a strategy. Add the fact that harvests need no pesticides when the crop grows inside a sealed room, and the case for the technology, on paper at least, becomes compelling.

C. The most ambitious projection stacks these systems in layers. If a plant needs only water, nutrients and light, then it need not be planted horizontally in a field at all; it can be stacked on shelves, one floor above another, inside a warehouse or disused factory. Vertical farms, as these buildings are known, can therefore grow a great deal of food on a remarkably small footprint — the footprint, essentially, of a city block. This appeals directly to the geography of modern hunger. The best farmland lies far from the consumers who eat its produce, and moving a head of lettuce across a continent burns fuel, wilts the crop and delays its freshness. Grow the same lettuce inside a building ten minutes from the supermarket and the journey collapses to a short van ride. Because the climate inside is controlled, the season becomes irrelevant: a leaf can be harvested in December that tastes like June. Such buildings are, in principle, immune to drought, flood and the erratic weather that now punctuates every growing year. For coastal cities with no room to expand, the pitch is irresistible: the farm moves into the city instead of the city moving out into the farmland.

D. The catch, the engineers will tell you over dinner, is light and power. A field receives its energy free, from a sun that has shone for four billion years; a vertical farm must manufacture every photon its plants receive. The lamps that substitute for sunlight, and the pumps, fans and climate systems that keep the room temperate, draw an electric bill that dwarfs the modest sum saved on water. Early commercial facilities discovered this the hard way, discovering that the greens they harvested cost more to produce than the ones shipped in from California, no matter how fresh. Critics argue that stacking crops under lamps makes sense only for leafy, high-value, fast-turning produce — herbs and salad leaves — and never for staple grains, which a field grows cheaply under a sky. A handful of studies have explored whether rooftop solar panels can power such buildings, and their conclusions are gently encouraging: with enough panel area, a small installation can approach energy independence. But that is a long way from a grid-independent farm at industrial scale. The technology's limits, in other words, are not botanical but economic and energetic.

E. Honest proponents no longer claim that hydroponics will feed the world. That was the marketing language of a decade ago, and the failures of over-leveraged start-ups have chastened the field. The more defensible position is narrower and stronger. Hydroponics will not replace the wheat field, but it may carve out a permanent niche beside it: supplying fragile, perishable greens close to the cities that cannot wait, saving water in the driest regions, and offering a controlled environment in which the next generation of crop varieties can be tested. It works best, researchers now say, where its strengths are genuine and its costs are tolerable — not as a rival to the soil, which took ten thousand years to teach us how to use, but as a complement to it. The tomato, it turns out, did not need dirt; but the farmer still needs sunlight, cheap power and a bill he can afford. Those three conditions, more than any invention in nutrient chemistry, will decide whether the farm of the future stays a curiosity or becomes a fixture.

Questions 1-4

Choose the correct heading for paragraphs B, C, D and E from the list of headings below.

List of Headings i. The two ordinary jobs that soil performs ii. Why water is the reason the idea suddenly matters iii. Stacking crops inside a building near the consumer iv. The discovery that lamps can be replaced entirely by sunlight v. The energetic and economic catch behind the promise vi. A realistic, modest role for the method vii. Why wheat will soon be grown under LED lamps

1. Paragraph B: ____
2. Paragraph C: ____
3. Paragraph D: ____
4. Paragraph E: ____

Questions 5-8

Choose the correct letter, A, B, C or D.

5. According to the passage, what does soil fundamentally provide? A. Nutrients dissolved in rain only. B. Physical support and a store of dissolved minerals. C. Warmth for the seeds. D. Protection from insects.

6. How much less water can a closed-loop hydroponic system use? A. About 80–90 per cent less than open irrigation. B. About 5 per cent less than field farming. C. It uses slightly more water than a field. D. It uses no water at all.

7. Why does stacking crops vertically appeal to dense cities? A. It requires no building at all. B. It produces large amounts of food on a very small footprint near consumers. C. It eliminates the need for nutrients. D. It grows wheat more cheaply than a field.

8. What is the main practical obstacle to vertical farming? A. Plants refuse to grow indoors. B. The lamps and climate systems draw large amounts of power. C. Lettuce cannot be stacked. D. Cities ban warehouses.

Questions 9-13

Do the following statements agree with the claims of the writer?

Write:

• TRUE if the statement agrees with the information
• FALSE if the statement contradicts the information
• NOT GIVEN if there is no information on this

9. In hydroponics, roots are supplied with water containing measured nutrients.
10. Conventional agriculture uses less than half of humanity's fresh water.
11. A kilogram of lettuce in a recirculating system can be grown on roughly two to three litres of water.
12. Rooftop solar has already made commercial vertical farms fully grid-independent worldwide.
13. Hydroponics is expected to replace conventional wheat production entirely.

Questions 14-15

Complete the summary below using NO MORE THAN TWO WORDS from the passage.

Soil mainly provides support and a mineral (14) __________, but a closed-loop installation returns unused solution to the roots, achieving savings of roughly eighty to ninety per cent of (15) __________.

答案与解析

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