Technology & Medicine › Atomic & space age › Haber–Bosch nitrogen fertilizer
Green Revolution (Borlaug)
c. 1945–1970s (Borlaug's wheat; IR8 rice 1966)· Event· Tools, energy & materials
Mostly agreedGood evidence; some details, dates or numbers uncertain.
From the 1940s to the 1970s, high-yield wheat and rice, fertilizer and irrigation sharply raised grain harvests across Asia and Latin America.
See it on the Technology & Medicine map →How it works
Norman Borlaug, an American plant scientist working in Mexico from 1944 with Rockefeller Foundation support, bred short, sturdy, disease-resistant wheat that could take heavy fertilizer without toppling over. Mexico became self-sufficient in wheat, and India and Pakistan nearly doubled wheat output between 1965 and 1970. IR8 'miracle rice', released in 1966 by the International Rice Research Institute (IRRI) in the Philippines, did the same for rice.
Why it mattered
It fed a fast-growing world and averted widely predicted famines; Borlaug won the 1970 Nobel Peace Prize. South Korea's Tongil rice (통일벼), bred from IRRI lines, ended its 1970s rice shortages.
How we know
FAO and national harvest statistics, and breeding records of CIMMYT in Mexico and IRRI; economists' studies find yields per hectare roughly doubled where the new varieties spread.
Still unknown or debated
Critics cite heavy water and chemical use, soil damage and gains skewed toward richer farmers; how to weigh these against the food gained is still debated.
Connections (2)
▸Haber–Bosch nitrogen fertilizer was the fertilizer behind the Green Revolution (Borlaug)Well documented
The connection
The new short wheat and rice gave big yields only with heavy nitrogen fertilizer, which Haber–Bosch factories made cheap. Older, taller varieties fell over when fertilized that heavily. Fertilizer use in developing countries rose many times over between the 1960s and 1980s.
When and how
Fertilizer plants built rapidly worldwide after 1945; Mexico from the 1950s; India and Pakistan from 1965–66.
How we know
Field trials showed the new varieties' yields depended on fertilizer; FAO statistics show fertilizer use and grain yields rising together.
Debates and open questions
Fertilizer runoff pollutes water and creates oxygen-starved 'dead zones' in seas; how much nitrogen farming can sustainably use is a live debate.
▸Classical genetics (genes on chromosomes) guided the breeding of the Green Revolution (Borlaug)Mostly agreed
The connection
Breeders used Mendel's and Morgan's rules of inheritance to combine traits on purpose. Borlaug crossed thousands of wheat lines, adding dwarfing genes from the Japanese variety Norin 10 to make short stems that could hold heavy grain. IRRI likewise crossed Indonesian and Taiwanese rice to create IR8.
When and how
Mexico, 1950s (Borlaug, using Norin 10 crosses from Orville Vogel at Washington State); Los Baños, Philippines, 1962–66 (IRRI's IR8).
How sure are we?
Pedigree records trace each variety's gene sources, and the main wheat dwarfing genes (Rht1 and Rht2) were later identified at the DNA level.
Debates and open questions
How much credit belongs to Borlaug versus the Japanese, American and Mexican breeders whose genes and work he built on is still debated.