A long-term precision agriculture project

Researchers have been applying precision crop and soil management research techniques on a 75-acre field laboratory near Ames. The field is divided into two equal tracts for corn-soybean rotation and yields were monitored during the 1996 and 1997 growing seasons.

The two tracts were divided into one-half acre grids for soil sampling purposes. In addition, soil sampling was conducted on selected transects across the two tracts. Tests were run on nutrients and pest levels.


  • A detailed soil survey, field contour map, and electromagnetic induction (EMI) readings have been completed.
  • A permanent weather station is in place.
  • Remote sensing by using different light spectra was used.
  • Soil nitrate and corn stalk nitrate were determined at selected field sites.
  • Small plant samples were taken to assess nutrient availability.
  • Corn and soybeans were routinely scouted to assess growth stages and pest problems, and to designate any infestation by using global positioning systems (GPS).

The field was originally selected as a research field because of variability in its soil properties. This is substantiated by organic matter ranging from less than 1.0 percent to 10 percent, soil pH from 5.2 to 8.5, phosphorus from 1.0 ppm to 78 ppm (Bray test) and 2.0 ppm to 33.0 (Olsen test), field slope from zero to C slope, and a wide range in soybean cyst nematode egg counts.

The 1997 corn yield ranged from less than 100 to more than 150 bushels per acre and soybean yield from less than 20 to more than 60 bushels per acre. Insufficient water limited yields.

Researchers are now selecting treatments for crop year 1998. The primary objective is to study the effect of the variation in soil properties on the crop response to selected treatments. A field day in August will provide the opportunity to review and share results and to show the 1998 practices selected.

This article originally appeared on page 5 of the IC-480 (4c Precision Ag Edition) -- April 9, 1998 issue.

Updated 04/08/1998 - 1:00pm