Less than 1 percent of American cropland is under certified organic production. If the other 99 percent were to switch to organic and had to fertilize crops without any synthetic nitrogen fertilizer, that would require a lot more composted animal manure. To supply enough organic fertilizer, the U.S. cattle population would have to increase roughly fivefold. And because those animals would have to be raised organically on forage crops, much of the land in the lower 48 states would need to be converted to pasture. Organic field crops also have lower yields per hectare. If Europe tried to feed itself organically, it would need an additional 28 million hectares of cropland, equal to all of the remaining forest cover in France, Germany, Britain, and Denmark combined.