May 13, 2005. The richest soil in the USA is in Illinois and Indiana. This is a picture of Indiana. High producivity of corn that grows fifteen feet tall. To the right in this picture is a mobile irrigation system that travels across the soil on wheels. The wheels are not easily seen as after three days of high wind it's taking 'Dust Bowl' characteristics. The soil drys with the wind removing it's moisture and carrying it away with the wind. Kindly remember this soil has become productive after generations of tender loving care. It's productivity is due to longevity and care. The depth in feet of it's nature is perhaps three feet but the highest productivity is only 'crop root' depth of 12 to 18 inches. Inches of 'top soil' are important and is currently being carried away with the wind.