Borlaug, who won the Nobel Peace Prize in 1970 and was hailed by Time magazine in 1999 as one of the 100 most influential minds of the 20th century, died at his home in Dallas from complications of cancer, a Texas A&M University spokeswoman said.
In the 1940s, when the specter of famine was stalking much of the world, Borlaug collected thousands of strains of wheat from around the globe and tediously crossbred them to produce varieties that were much higher yielding and resistant to the diseases that were destroying crops.
He spearheaded efforts to spread these new strains around the world, sparking an explosion in crop yields that helped lead devastated countries toward food self-sufficiency.
In 1960, before his techniques were widely adopted, the world produced 692 million tons of grain for 2.2 billion people. By 1992, largely as a result of Borlaug's pioneering techniques, it was producing 1.9 billion tons for 5.6 billion people -- using only 1% more land. India and Pakistan are now agriculturally self-sufficient as a result of his intervention.
His efforts did not go unrecognized: Borlaug became one of only five people in history to score the trifecta of humanitarian achievement, winning the Nobel Peace Prize, the Presidential Medal of Freedom and the Congressional Gold Medal -- placing him in the company of the Rev. Martin Luther King Jr., Mother Teresa, Nelson Mandela and Elie Wiesel.
On Borlaug's 90th birthday, former President Carter said that he "has been demonstrating practical ways to give people of the entire world a higher quality of life. . . . He is a true humanitarian."
Former South Dakota Sen. George McGovern added that Borlaug's "scientific leadership not only saved people from starvation, but the high-yield seeds he bred saved millions of square miles of wildlife from being plowed down. He is one of the great men of our age."
Ever since 19th century British economist Thomas Malthus first predicted that the world's population would eventually outstrip its capacity for growing food, prophets of doom had envisioned catastrophe right around the corner.
Such a disaster was actually quite near beginning in the late 1930s. Between 1939 and 1942, Mexico's wheat harvest had been halved by stem rust, a fungus whose airborne spores infect stems and leaves, causing the grain to shrivel. India, Pakistan, China and other countries were also facing the prospect of widespread starvation.
Alarmed by how food shortages might affect the war effort, the Rockefeller Foundation -- largely at the instigation of Secretary of Agriculture Henry Wallace -- established the Cooperative Wheat Research and Production Program in Mexico. It later became known as the International Maize and Wheat Improvement Center. Borlaug signed on in 1944 after finishing his wartime obligations as a chemist at E.I. du Pont de Nemours.
Borlaug collected wheat strains from around the world and began crossbreeding them, a process he later recalled as "mind-warpingly tedious." To speed things up, he planted two crops per year, a summer crop in the low-quality, high-altitude soils near Mexico City and a winter crop hundreds of miles to the north in the low-lying Yaqui Valley.
Within five years, Borlaug had produced a strain that was resistant to rust, was more productive than existing strains and grew in both climates when given adequate fertilizer and water.
But there was still one problem. Evolution had favored wheat strains with long, slender stalks that allowed the wheat to rise above the shade of nearby weeds. With the added weight of the extra grain of Borlaug's strain, the stalks tended to collapse when irrigated or rained on, reducing yields.
After thousands of fruitless attempts to produce wheat with shorter stalks, Borlaug encountered a Japanese dwarf variety. After thousands more attempts, by 1954 he had succeeded in producing a short-stalked variety that was rust-resistant and high-yielding.
Using the new strains, Mexico, which had imported 60% of its wheat in the early 1940s, became self-sufficient by 1956.
In 1954, a rust epidemic hit the American Midwest, destroying three-quarters of the durum wheat crop that was used for making pasta and accelerating use of the new strains in the United States. There has not been a similar outbreak since.
Using Borlaug's techniques, scientists soon developed similar high-yield strains of rice and corn.
In the early 1960s, India and Pakistan were confronting famine, and the International Wheat and Maize Project sent Borlaug to intervene.
By 1965, the new crops were 98% bigger than the previous year's, and the Asian subcontinent was placed on a new path. India ordered 18,000 tons of seed from Mexico, and the reap was so big that there was a shortage of labor to harvest it, too few bullock carts to haul it to the threshing floor and an insufficiency of jute bags, trucks, rail cars and storage facilities.
By 1968, Pakistan was self-sufficient in food production. India joined it in that status in 1974.
Because of his efforts, Borlaug was awarded the 1970 Nobel Peace Prize.
Eventually, however, a backlash developed. In the 1980s, environmental groups began pressuring foundations and the World Bank to stop funding shipments of fertilizer to developing countries, particularly in Africa. Critics contended that the inorganic fertilizers used caused massive pollution; they argued in favor of "sustainable" agriculture using "natural" fertilizers like cow manure.
Borlaug was indignant. Using manure would require a massive expansion of the lands required for grazing the cattle and consume much of the extra grain that would be produced. At best, he said, such efforts could support no more than 4 billion people worldwide, well under the nearly 7 billion now inhabiting the planet.
"Some of the environmental lobbyists of the Western nations are the salt of the Earth, but many of them are elitists," he told the Atlantic Monthly magazine. "They've never experienced the physical sensation of hunger. They do their lobbying from comfortable office suites in Washington or Brussels. If they lived just one month amid the misery of the developing world, as I have for 50 years, they'd be crying out for tractors and fertilizer and irrigation canals and be outraged that fashionable elitists back home were trying to deny them these things."
Borlaug formally retired from the International Wheat and Maize Project in 1979, becoming a professor at Texas A&M University. But in 1984, he got a call from Japanese industrialist Ryoichi Sasakawa, who offered Borlaug funding for five years of work to aid agriculture in Africa.
Speaking through an interpreter, Borlaug said, "I'm 71. I'm too old to start again." Sasakawa called back the next morning and said, "I'm 15 years older than you, so I guess we should have started yesterday. Let's start tomorrow."
Borlaug later said: "I assumed we'd do a few years of research first, but after I saw the terrible circumstances there, I said, 'Let's just start growing.' " He soon had projects running in several countries, including Benin, Ethiopia, Ghana, Nigeria, Sudan and Tanzania.
But progress has been much slower in Africa than in Asia, principally because -- unlike in the Asian subcontinent -- the region lacked the infrastructure of roads and irrigation systems necessary to support high-intensity agriculture. Armed conflicts have also impeded the work, and starvation remains widespread.
Meanwhile, the world is facing a new threat, a virulent strain of black stem rust called Ug99, first discovered in Uganda in 1999, that attacks the resistant strains of grain. It has subsequently been found in Yemen and Sudan and, because rust spores are carried by the jet stream, is likely to reach crops around the world.
Norman Ernest Borlaug was born March 25, 1914, on a farm near Cresco, Iowa, in a portion of the state called "little Norway" because so many of its residents were immigrants from that country. His education began in a one-room schoolhouse.
According to his friend Kenneth M. Quinn, president of the World Food Prize Foundation, Borlaug developed a dogged tenacity from participating in his high school wrestling program -- a tenacity that propelled him to the top of the intercollegiate wrestling world and election to the Iowa Wrestling Hall of Fame.
After graduating from high school in the depths of the Depression, he worked for 50 cents a day as a farmhand to earn enough money to enroll at the University of Minnesota. He put himself through school working in a coffee shop, parking cars and serving meals in a sorority house. In the summers, he worked for the U.S. Forest Service.
He had planned to join the Forest Service upon receiving his degree in forestry in 1937, but shortly before that could happen he received a letter from his supervisor saying a shortage of funds precluded him from starting for at least six months.
Coincidentally, he attended a lecture on wheat rust by plant pathologist Elvin Charles Stakman and was so impressed that he enrolled in the graduate program to work with Stakman, receiving his doctorate in plant pathology from Minnesota in 1942.
Along with his wife, the former Margaret G. Gibson, Borlaug is survived by daughter Jeanie Borlaug Laube, son William Gibson Borlaug, five grandchildren and six great-grandchildren.
The family asked that instead of flowers, donations be sent to the Borlaug International Scholars Fund. Plans for a memorial service at Texas A&M were pending.