North Dakota State University's Research Plot No. 2 is possibly the only agricultural research plot in the world to have been continuously planted to wheat. Located on the NDSU campus, it was planted to wheat 125 years ago.

In 1991, Research Plot No. 2, along with NDSU's Flax Plot No. 30, was entered into the National Register of Historic Places. In 1999, David Weller, research plant pathologist with the USDA's Agricultural Research Service at the Root Disease and Biological Control Research Unit in Pullman, Wash., said, "Basically, the NDSU Wheat Plot No. 2 is a national treasure."

For scientists interested in soil fertility, crop rotation and naturally occurring organisms that control plant diseases, Plot No. 2 is a valuable resource. Prior to being sown to wheat, the plot had been tallgrass prairie. After 10 years of continuous cropping to wheat, the poor crop yields that were experienced were believed to be due to poor soil fertility or "wheat-sick" soil, as it was termed then.

W.M. Hays, NDSU agriculturalist, set up a series of 29 one-acre plots in 1892. Hays used crop rotation to assess performance, but kept Plot No. 1 and Plot No. 2 as control plots. After experimentation, H.L. Bolley, NDSU's first plant pathologist, proved that this "wheat-sick" soil that was causing decreased yields actually was due to a buildup of plant pathogens (disease), not poor fertility. Bolley made recommendations in 1909 regarding crop rotation, seed treatments and wheat diseases that still are practiced today.

"There is a general belief that the reason natural ecosystems have less disease epidemics than monoculture systems is because the greater diversity acts as a buffer, so not all plants in the mixture will be susceptible to the disease," says Stephen Neate, NDSU plant pathologist and associate professor. "This plot has demonstrated that a monoculture can work."

Neate says microbes in the soil are part of a large, balanced food web where some microbes eat or decay the plot material, with the bigger microbes and soil animals eating the smaller ones.

"The pathogens are part of this balanced food web," Neate says. "It seems that in the early days of planting continuous wheat, the web was out of balance and the pathogens were able to dominate. Now, after many years of monoculture, these soils have returned to a balanced food web. What is scientifically important about Plot No. 2 is that testing has shown that this soil, as with some other soils around the world that are continuously planted to the same crop, has developed soil microbes that produce a chemical that biologically suppresses "take-all," a serious root disease in cereal crops. These types of situations give us an unparalleled opportunity to study the soil ecosystem and likely will give us information on how to sustainably manage our agricultural soils."

Marcia McMullen, NDSU Extension Service plant pathologist, says the plot is a valuable source of biological information and an important site for screening against root diseases.

In the late 1800s, wheat was the No. 1 crop in North Dakota. An entry by Hays in the May 1893 North Dakota Agricultural Experiment Station Bulletin says, "Wheat should continue as our main and most profitable crop. What country can better raise wheat or with what commodity can we better compete in the markets of the world?"

Wheat continues to be North Dakota's No. 1 agricultural commodity, producing 21.4 percent of the state's total cash receipts. North Dakota is the top producer of spring wheat in the U.S.