"We've assigned Muscatune soil the highest productivity index of 147 in Bulletin 811 -- Optimum Crop Productivity Ratings for Illinois Soils. Under optimum management, Muscatune soil registered a 10-year average of 190 bushels for corn, up 10 bushels for a decade earlier," Olson said.
All of the other Illinois soil types and complexes are now being compared with Muscatune soil properties and 10-year average crop yields to determine each soil's productivity index, which provides is a relative rating for all Illinois soils.
Ipava, Flanagan and Muscatune soils all jointly held the highest rating just 30 years ago. The Flanagan and Ipava soils, common in East-Central Illinois, are still highly productive and considered Class A prime agricultural land, but Muscatune soil currently holds the highest position in the state's soil productivity indices.
"We think of soils in East-Central Illinois as the most productive soil, and they are very productive. But Drummer/Flanagan, which is the predominant soil in East-Central Illinois, tends not to have as deep of a root zone as Muscatune. Drummer/Flanagan is still Class A prime agricultural land though," Olson said.
Soil surveying work in Illinois began in 1902 in Clay, Clinton, St. Clair and Tazewell Counties. Cyril Hopkins, then head of the U of I Department of Agronomy, was in charge of the soil survey even though it was a cooperative endeavor of federal, state, and local government.
Today, it is still a cooperative effort between 9 state and federal agencies, with the Natural Resources Conservation Service (NRCS) being the lead agency.
"Muscatune soil is found in association with Osco soil (950,000 acres) and Sable soil (900,000 acres). This soil association is primarily used as cropland and represents approximately 9% of the 24 million acres of Illinois currently used for cropland," said Bob McLeese, Illinois NRCS soil survey leader.
Muscatune/Osco/Sable is soil association predominant on the U of I Northwestern Illinois Agricultural Research Center near Monmouth, Illinois where the recent sampling took place.
Soil productivity indices are used in land appraisal, land sales and real estate tax assessment.
"When farms are sold, productivity indices are used to value the farmland. If the optimum productivity index is above 133, it's considered Class A prime agricultural land," Olson said.
"Also, the state mandates that farmland to be assessed for its agricultural use value based on the productivity indices," he said.
Olson recommends that greater state efforts be made to insure the protection and preservation Class A prime agricultural land in Illinois, including land with Muscatune, Osco and Sable soils.
"There is a finite supply of Class A prime agricultural land in Illinois and, once it is developed, there's very little likelihood that it will ever be returned to agricultural production. The state has some provisions to protect prime farmland in rural areas, but prime farmland occurring within expanding urban areas are exempted since land use is controlled in urban areas by local zoning," he said.
To view Bulletin 811 -- Optimum Crop Productivity Ratings for Illinois Soils online, go to www.nres.uiuc.edu/soilproductivity.