 A long-term field study comparing organic/conventional agriculture carried out over 21 years in Switzerland concluded that "Crop yields of the organic systems averaged over 21 experimental years at 80% of the conventional ones.The fertilizer input, however, was 34 – 51% lower, indicating an efficient production.The organic farming systems used 20 – 56% less energy to produce a
crop unit and per land area this difference was 36 – 53%.