Did the Haber-Bosch process enable the population explosion? 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 &quot;detonator of the population explosion&quot;,
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 &quot;Bio&quot; 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?
There are a number of factors that went/are going into the population explosion, food is only one vaccination and antibiotics are a big factor as well.  within food fertilizer is again only one of many factors. Better crop strains, mechanized and better farming techniques, soil science, pesticides, refrigeration, and a dozen other factors contributed.  Keep in mind artificial fertilizers get less important as you go back in time as well so calling it the detonator is incorrect and misleading. 

Now when considering crop rotation, crop rotation has pros and cons, there are several nutrients plants need and rotation only helps with some of them, and it relies on having compatible crops to rotate which not every crop or environment has.

Keep in mind the piece wikipedia is quoting is not a peer reviewed paper but an essay in nature, which explains it is referring to several modern countries that fertilize almost exclusively with artificial fertilizers. It is not claiming they cannot use other fertilizers.