Prairie Soils

North Dakota is a prairie state, and we grow important crops that help feed the world. Now, try to visualize the major crop producing areas of the world: The “Breadbaskets of the World” if you will. Now visualize the prairie areas of the world. Are they the same areas? They are. It is prairie, more specifically prairie soils that feed the world. It is so obvious to us that we give it little consideration, but it is the prairie soils that form the black, rich, fertile growing medium that we have converted to cropland. Prairie rules! The forested soils of the world, for example are not nearly as productive. So what is it about the soil that forms under prairie that makes for such a fertile plant growing medium?

Soil forms from the climate and living organisms acting on parent material as influenced by topography and relief over time. However, perhaps the most significant factor in the development of prairie soil is the way prairie plants grow and die.

As many of you know, grass roots are extensive and grow close to the soil surface. It may surprise you, but over the course of a growing season on the prairie, between 80-90% of all the plant growth occurs underground. Let me rephrase that. When you watch the growth of prairie over the summer, you are observing only 10-20% of all the plant growth. So, most of that growth is in the ground. Furthermore, about one-third of the grass roots die and are replaced each year. That means that in three years the equivalent of the entire root systems of all the grasses will have died in the upper surface of the soil. Much of that root material will become soil organic matter. Over time this topsoil will become black due to this “melanization” process.

That organic matter is very important because it contains and will hold onto important plant nutrients such as nitrogen, has a high water holding capacity, and is a good rooting medium.

We have put the prairie soils to work here in North Dakota and elsewhere. We put it to work raising forage to feed livestock and we put it to work raising crops. But as we all know, the real trick, is determining which use can best sustain the productivity and economic viability of that precious resource.

Chuck Lura

Natural North Dakota is supported by NDSU Central Grasslands Research Extension Center and Minot State University-Bottineau, and by the members of Prairie Public. Thanks to Sunny 101.9 in Bottineau for their recording services.