Im a bit confused on how crucial Nitrogen fixation with the Haber-Bosch process really was. On the Wikipedia page of the Haber-Bosch process it says:
In combination with pesticides, these fertilizers have quadrupled the productivity of agricultural land.
With average crop yields remaining at the 1900 level the crop harvest in the year 2000 would have required nearly four times more land and the cultivated area would have claimed nearly half of all ice-free continents, rather than under 15% of the total land area that is required today.
Due to its dramatic impact on the human ability to grow food, the Haber process served as the "detonator of the population explosion", enabling the global population to increase from 1.6 billion in 1900 to today's 7 billion.
However I have read that the products labelled "Bio" in the stores in Switzerland that don't use nitrogen fertilizers have only about 20% lower yields, which is a dramatically different number than what the Wikipedia page on the Haber-Bosch process claims (quadrupling of productivity).
What am I missing? Did the nitrogen cycle change so much so that we don't need nitrogen fertilizer nowadays? Did new technology enable us to get similar yields without nitrogen fertilization? What explains these numbers? Was crop rotation an unknown concept in the 1900’s?