15.4 Natural and synthetic fertilizers help restore soil fertility ° Natural occurring fertilizers are compost(堆肥) and minerals. The natural occurring minerals are limited In 1913, a German scientist, Fritz Haber, developed a process for producing ammonia from hydrogen and nitrogen 2500 0 1500 0 是。 °5657585966162636465666766707n2 Fig 15.13 between 1956 Year and 1972 world crop yields Crop yield Nitrogen fertilizer need grew in tandem with increases in the use of N-P-K system nitrogen fertilizers15.4 Natural and synthetic fertilizers help restore soil fertility • Natural occurring fertilizers are compost (堆肥) and minerals. • The natural occurring minerals are limited. • In 1913, a German scientist, Fritz Haber, developed a process for producing ammonia from hydrogen and nitrogen. N-P-K system Fig 15.13 between 1956 and 1972 world crop yields grew in tandem with increases in the use of nitrogen fertilizers Year