Iowa farmer Clay Mitchell says precision technologies boost his crop yields.

"Controlled traffic helps create soil qualities in which we see higher yields," Mitchell says.

Mitchell uses a real-time kinematic (RTK) guidance system where tractors, combines, sprayers and planters drive on exactly the same paths from one year to the next. GPS devices allow Mitchell to plant seed, apply fertilizer and spray herbicides with centimeter accuracy.

Driving the same path reduces compaction of topsoil that can reduce yield and allows Mitchell to precisely track performance row by row.

After 5 years, soil tests showed better water flow in Mitchell's no-till operation than on neighboring farms.

"By using a no-till system with a lot of residue cover, we're trying to simulate the soil conditions of a forest floor," says Mitchell, who will speak at the 2010 National No-Tillage Conference in Des Moines from Jan. 13 to 16. "Soil is protected from direct rainfall, allowing it to maintain its sponginess.

"Compared to conventional-tilled fields of neighbors, who saw water infiltration rates of about 0.2 inch per hour, we saw infiltration rates of 4 inches per hour outside of traffic lanes. This is a huge deal for us because we used to try to make small incremental improvements. It's not very often we see 10 or 20 times improvement in erosion."

Mitchell also noted improvements in machinery efficiency. Not only do his GPS-guided tractors travel less ground, they also exert 40% less effort while driving on heavily compacted traffic lanes. That results in significant energy savings.

Mitchell takes advantage of intercropping corn and soybeans by alternating 30-foot swaths of each crop in fields. This allows the corn to take advantage of additional sunlight to improve yields without causing too much of a drop in the soybean crop.

Maps showing yield in single rows allow him to correct mistakes and refine delivery of fertilizer and chemicals.

"When everything becomes aligned, you reveal errors. Differences as high as 83 bushels can be seen between rows," he says.

Even with all the improvements, there are still challenges. Mitchell notes that heavy rains in recent years have created problems with rutting in traffic lanes. He also says he's dealing with topsoil migration and looking at the possibility of using automated GPS to distribute silt from grass waterways on parts of the field that show topsoil deficiencies.

Despite these kinks, Mitchell says his system is paying off.

"For grain farmers, the sum of their work is contained in the fullness of their bins at the end of the year," Mitchell says. "This is really a fantastic story of energy savings and soil improvement on our farm."