Last lesson you learned to classify a farm by its inputs. Intensive means a lot goes in per hectare and a lot comes out. That was a label. This lesson is about what the "a lot in" actually is.
It turns out to be mostly one thing: nitrogen, made in a factory, from gas. Where that came from, what it cost, and what you could use instead is the first half of this lesson.
The second half is about the other end of the system. The same field feeds a very different number of people depending on whether the crop goes to you or to an animal first. That is not an opinion, it is arithmetic, and it is currently on a ballot paper. On 27 September, Swiss voters decide whether the country should deliberately shift its farming and its diet towards plants. Whatever you think of that, you are about to have the evidence both sides are using.
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5.2.7 The Green Revolution (also known as the Third Agricultural Revolution in the 1950s and 1960s) used breeding of high-yielding crop plants—combined with increased and improved irrigation systems, synthetic fertilizer and application of pesticides—to increase food security. It has been criticized for its sociocultural, economic and environmental consequences.
There are both positive and negative consequences of the Green Revolution, and it did not occur in all developing nations. Improved productivity depended on fixing nitrogen into synthetic fertilizers, which makes their production fossil-fuel dependent.
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The Green Revolution was not an invention. It was four things that only work as a set: high-yielding varieties of wheat and rice, irrigation, synthetic fertiliser, and pesticides.
Start with the seed, because the clever part is the part nobody explains. The new wheats were short. Give a traditional tall wheat plenty of nitrogen and it puts the extra growth into stem, grows top-heavy, and flattens in the first storm before harvest. Breed the plant short and two things happen at once. The extra growth goes into grain instead of straw, and the plant stays standing under a heavy dose of fertiliser.
So the seed did not raise the yield by itself. It made the fertiliser usable.
That is why the package has to be bought whole. The variety needs the fertiliser. The fertiliser only pays if water is reliable, so it needs irrigation. A dense, uniform, well-fed crop is an excellent meal for pests and diseases, so it needs pesticides. Remove any one part and most of the yield advantage goes, but you have already paid for the seed.
The results were real and fast. Wheat harvests in India and Pakistan rose sharply within five years, and famine forecasts that had been treated as certain did not happen.
Task
The statement says the Green Revolution has been criticised for its sociocultural, economic and environmental consequences. Those are three separate bills, and they did not fall on the same people.
Economic. The package has to be bought again every season. That rewards farmers who already have capital, land and access to credit, and pushes those who do not into debt to keep up. It also concentrated where the water already was: Punjab has about 1.5% of India's land and now grows roughly 20% of its wheat.
Sociocultural. Thousands of local landraces, each adapted to a particular valley or soil, were replaced by a handful of varieties, and the knowledge of how to grow them went with them. The revolution also did not happen everywhere. It largely bypassed sub-Saharan Africa, so "it fed the world" is a claim that does not hold on every continent.
Environmental. In Punjab the irrigation water came from underground. Tube wells multiplied, and the 2022 Central Ground Water Board assessment classified 114 of Punjab's 150 blocks as over-exploited, with 19 more critical or semi-critical. Add the nutrients washing off those fields into rivers, which is the eutrophication you met in Topic 4.
None of this makes the yields imaginary. It makes them expensive in ways that were not counted at the time.
Task
Complete the table. For each consequence, decide which of the three categories it belongs to and say what about the package caused it.
| Consequence | Which category? | What about the package caused it? |
|---|---|---|
| Farmers borrow money every season to buy seed, fertiliser and pesticide | ||
| Local wheat varieties, and the knowledge of them, disappear | ||
| The water table under central Punjab falls year after year |
Watch with one question in mind: why was nitrogen the thing that limited how much food the world could grow?
https://www.youtube.com/watch?v=QQkmJI63ykI
Nitrogen is the nutrient crops run out of first. It is also 78% of the air above the field, which sounds like an easy problem until you look at the molecule. Atmospheric nitrogen is Nâ‚‚, two atoms held by a triple bond, and plants cannot break it. Before 1909, the nitrogen entering a field arrived only through nitrogen-fixing bacteria, manure, or imported deposits of guano and nitrate.
The Haber-Bosch process forces the reaction instead. Nitrogen from the air is combined with hydrogen at around 450°C and roughly 200 times atmospheric pressure to make ammonia, which becomes fertiliser. The hydrogen comes from natural gas.
Read that last sentence again, because everything else in this lesson hangs off it. A bag of nitrogen fertiliser begins as fossil fuel. Making ammonia consumes 1 to 2% of the world's energy and about 5% of its natural gas, and releases 1 to 2% of global carbon dioxide emissions.
It also feeds you. Roughly half the nitrogen atoms in your body were fixed in a factory rather than by a bacterium.
Task
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5.2.8 Synthetic fertilizers are needed in many intensive systems to maintain high commercial productivity at the expense of sustainability. In sustainable agriculture, there are other methods for improving soil fertility.
These techniques include restoring natural productivity by fallowing, using organic fertilizer from farm animals or humanure, herbal mixed leys, use of mycorrhizae, continuous cover forestry and agroforestry.
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