15. 4 Natural and synthetic fertilizers help restore soil fertility Natural occurring fertilizers are compost(#E HE)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 00 13500 L1000 Qc s 。 5657585960616263646566676869707172 Fig 15.13 between 1956 ear and 1972 world crop yields E 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