USDA NRCS Initiates Study of How Tillage Affects Soil Quality

USDA NRCS Initiates Study of How Tillage Affects Soil Quality

Dec. 4, 2009

Soil scientists with the USDA Natural Resources Conservation Service are currently working on a project that will help farmers know how tillage methods impact soil quality. According to NRCS Soil Scientist Dave Kohake, the Dynamic Soils Properties study, based out of Lincoln, Neb., is the first of its kind for NRCS.

Taking soil samples in a residue-covered field

NRCS Soil Scientist Casey Latta identifies soil properties at one of the Dynamic Soil Properties study’s test sites in Lancaster County.  (Photo by Joanna Pope, NRCS)

“In the past, studies have dealt more with the soil’s intrinsic properties. This project will focus more on the dynamic soil properties affected by management,” Kohake said.

The Dynamic Soil Properties study is focusing on two tillage methods — conventional tillage and no-till. For this study’s purposes, a field is considered to have been conventionally tilled any time the soil has been disturbed with full-width tillage implements (i.e. disks, chisel plows, field cultivators). A field is considered to have been no-tilled if it has not had any manipulation to the soil’s surface within the past 15 years. A couple organically farmed sites will also be evaluated.

The Dynamic Soil Properties study team, which, in addition to Kohake, includes Casey Latta, Cindy Stiles, Deb Harms and Bruce Evans, identified five sites for each tillage method across southeast Nebraska with similar soil types. The team has been traveling around to these selected sites throughout the fall to collect soil samples.

Once at the site, the soil scientists prepare the test location by setting up a grid. Within the grid, five sampling pits are dug. The pits are all 16 inches deep. This is the depth where the impact of different farming techniques can be detected.

The soil scientists then begin identifying the different layers of soil. A sample of each layer is taken to the USDA’s National Soil Survey Center’s laboratory, located in Lincoln, Neb., for analysis.

The NSSC lab will check each site’s soil samples for several properties including bulk density and organic carbon content.

“The amount of organic carbon content found within soil is the best indicator we have for soil quality. The higher the carbon content, the higher the soil quality or health,” Kohake said.

This study will compare the lab results to show how conventional tillage, no-till, and organic farming methods impact soil properties. The results from this fall’s study should be available by next planting season.

Kohake said, “This study should provide some useful information on how different management systems are affecting various dynamic soil properties. Hopefully the information can be used to make better management decisions in the future for improving soil quality.”

For more information about soil quality, visit your local NRCS office or the Web Soil Survey.

USDA NRCS News Release