The soybean is one of the richest and cheapest sources of protein and is a staple in the diets of people and animals in numerous parts of the world. The seed contains 17 percent oil and 63 percent meal, 50 percent of which is protein. Because soybeans contain no starch, they are a good source of protein for diabetics. Soybeans are adapted to a wide range of soil types. Loamy soils are ideal. While heavy clay soils can lead to planting and emergence problems, once established, soybeans perform reasonably well. Soybean performance can be poor on sandy soils prone to drought stress.