For organically grown crops, farmer takes care of following
No use of chemical pesticides. Instead use organic pesticide
No use of chemical fertiliser.
Foods not processed using irradiation, industrial solvents, or synthetic food additives.
http://ucanr.edu/datastoreFiles/608-794.pdf
https://helix.northwestern.edu/article/organic-food-really-worth-extra-cost
https://en.wikipedia.org/wiki/Organic_food#Nutrients