在线英语听力室_免费在线英语听力学习网站

This is Scientific American's 60-second Science. I'm Steve Mirsky.

 Here’s a clip from last week’s CalTech commencement address by Secretary of Energy and physics Nobel Laureate Steven Chu.

 Most scientists are optimistic by nature. Part of my optimism comes from the fact that science has come to our aid in the past. As an example, I remind you of the agricultural revolution that occurred in the last century. In 1898, in his inaugural¹ speech, Sir William Crookes, President of the Royal Society, began with the warning “England and all civilized² nations stand in deadly peril³.” I tried.

 Crop rotation⁴ and manure⁵ were not sufficient to replenish⁶ the depleted⁷ soils, and he predicted that the fertilizer based on South American bird guano—just in case you’re wondering, guano is the technical term for bird doo-doo—and Chilean sodium⁸ nitrate would soon be exhausted⁹. The solution Crookes proposed was to create artificial fertilizer. “It is the chemist,” he declared, “who must come to the rescue.”

 In 1909, eleven years later, Fritz Haber demonstrated the catalytic synthesis of ammonia from air and hydrogen, a path unsuccessfully pursued by two distinguished¹⁰ chemists and future Nobel Prize winners, Walther Nernst and Wilhelm Ostwald. For this achievement, Haber was awarded the 1918 Noble Prize for Chemistry. But the production of fertilizer was considered so important that the industrialization of ammonia synthesis was recognized by a second Nobel Prize to Carl Bosch in 1931.

 The second part of the agricultural revolution was led by Norman Borlaug, who got the Nobel Peace Prize in 1970. He created hybrid¹¹ strains of wheat that increased the yield per acre four to seven fold in Mexico, India and Pakistan. Because of his work, the starvation of hundreds of millions of people was prevented.

Science and technology was the basis of the agricultural revolution, but current agricultural practices are not sustainable. And we need a second green revolution that will create perennial¹² plants for food, fiber¹³ and energy that fix their own nitrogen and draw precious nutrients¹⁴ into their roots for the following year.