QUINCY -- That the percentage of no-till practices in Illinois increased in corn but decreased in soybeans from 2015 to 2017 came as no surprise to Brad Smith.
"That's a trend we've been seeing for the last two or three years," said Smith, resource conservationist for the Pike County and Adams County soil and water conservation districts. "It seems like there's been less no-till beans than there was 10 years ago."
The Illinois biennial Soil Erosion and Cropland Tillage Transect Survey -- completed this spring and summer by the Illinois Department of Agriculture, in cooperation with Illinois' 97 soil and water conservation districts and the USDA Natural Resources Conservation Service -- also showed that conventional tillage practices increased in corn and soybeans.
"In the last couple of years, there's been some disease concerns, especially with corn after corn," Smith said. "Some producers may have jumped the gun and thought they needed to do more tillage to get rid of more corn residue. Crops are yielding more now, and with more yield, there's more residue."
Illinois farmers cite many reasons for increasing tillage, which reduces residue, over the past few years, including control of herbicide resistant weeds, early planting and harvest dates, and weather, the Department of Agriculture said.
Statewide, the survey shows the percentage of cropland below "T," the tolerable soil loss level, or the amount that can be replaced naturally by decomposition of crop residue, slipped from 80.4 percent in 2015 to 79.2 percent in 2017.
Leaving more crop residue on a field helps reduce the amount of soil leaving a field.
"Farmers that utilize mulch-till or no-till farming systems leave more residue/cover after planting, which in turn reduces the amount of soil material leaving their fields," according to survey information from the Hancock County Soil and Water Conservation District. "These and other best-management practices are being adopted voluntarily by Midwestern farmers in an effort to reduce the amount of nitrates and phosphates entering nearby water sources. These excess nutrients can contribute to lower water quality in streams, rivers and lakes."
The survey reviews preselected points in a county-- 539 in Hancock County, for example -- every two years to gather information on current crop type, previous year crop type, tillage system used and crop residue percentage, and whether erosion/cover crop was present.
Smith said the survey helps track trends across a county.
"The original survey was developed by Purdue University and supposed to be a fairly good measure on the whole county's tillage methods," he said.
The Department of Agriculture said one bright spot emerging in crop management for Midwestern farmers is use of cover crops.
"Anytime you add something to give you more ground cover throughout the year, it gives you a chance to protect our land from erosion between crops," Smith said. "Some of the cover crops also have some fertilizer value to them, too."
More information about the survey is online at agr.state.il.us/illinois-soil-conservation-transect-survey-reports.
The biennial Illinois Soil Erosion and Cropland Tillage Transect Survey looks at four tillage systems:
• No-till – Planting or drilling is accomplished in a narrow seedbed or slot created by coulters, row cleaners or disk openers. Crop residue greater than 60 percent is left on the soil surface after planting.
• Mulch-till – A full-width tillage system that leaves greater than 30 percent residue after planting.
• Reduced-till – A full-width tillage system that leaves 16 to 30 percent residue after planting.
• Conventional – A full-width tillage system that leaves 0 to 15 percent residue after planting.