Credit: Gidon Eshel Small-scale mixed-use agriculture that avoids synthetic fertilizers in favor of manure could eliminate agricultural greenhouse gas emissions if established across the United States' 100 million hectares of lush high quality cropland, according to a study by Gidon Eshel, publishing 3rd June 2021 in the open-access journal PLOS Biology. The minor catch: beef consumption would need to decrease, but by only 20%. Beef is the most resource-intensive food item that we regularly put into our shopping carts -- for every gram of protein, beef uses 7 times more cropland and 20 times as much water and emits 11 times the greenhouse gases. At the same time, cattle manure is a valuable source of natural fertilizer. Nitrogen-sparing agriculture avoids external inputs of nitrogen, such as synthetic fertilizers, instead relying on cattle manure and nitrogen-fixing crops to replenish soil nutrients.