where is the best farming soil in the us and where did all the dirt come from
Black Dirt Region The Black Dirt Region takes its name from the dark, extremely fertile soil left over from an ancient glacial lake bottom augmented by decades of past flooding of the Wallkill River. The 26,000 acres (10,400 ha) of muck left over is the largest concentration of such soil in the United States outside the Florida Everglades.[1]
Topsoil Topsoil is the upper, outermost layer of soil, usually the top 2 inches (5.1 cm) to 8 inches (20 cm). It has the highest concentration of organic matter and microorganisms and is where most of the Earth's biological soil activity occurs. Four elements constitute the composition of soil. Those elements are mineral particles, organic matter, water, and air. The volume of top soil consists of 50 to 80 percent of these particles which form the skeletal structure of most soils. This composition allows the soil to sustain its own weight, and other internal matter such as water and overlying landscape. Organic matter, another important element, varies on quantity on different soils. This provokes positive and negative effects or reactions on the soil. The strength of soil structure decreases with the presence of organic matter, creating weak bearing capacities. Organic matter condenses and settles in different ways under certain conditions, such as roadbeds and foundations. The skeletal structure becomes affected once the soil is dewatered. The soil's volume substantially decreases. It decomposes and suffers wind erosion.[1]