With harvest over and fields bare, there's a lot of talk about tillage this fall. Should you or shouldn't you do tillage? After all, there's a drought going on. So why till this fall? Won't tillage lose precious soil moisture?
"While we know there are benefits to different types of tillage in specific situations, some early On-Farm Network trials with deep ripping, using either an in-line or V-Ripper trials, rarely showed yield benefits sufficient to pay for the cost of the practice," says Tracy Blackmer. He is director of research for the On-Farm Network, a program offered by the Iowa Soybean Association.
During the 2003 and 2004 growing seasons, the On-Farm Network coordinated more than 100 replicated strip trials comparing strips with a John Deere 2100 minimum till in-line ripper that was set to till at a depth of 16 inches. Across both seasons, the average yield increase for the subsequent corn crop was less than 3 bushels per acre. Where beans were planted after ripping, the yield increase was less than 2 bushels per acre.
Besides the yield differences, Blackmer says he and the On-Farm Network farmers also learned:
* There were significant yield responses on some specific fields, even though it didn't pay on the average.
* The lower, heavier textured soils benefited the most from deep ripping in the fall.
* Where grower selected fields because of a known compaction problem, there was generally a profitable response from the practice.
* Ripping created a problem with stones brought to the surface in some fields, since the ripper tended to pull them to the surface. Removing the rocks resulted in considerable extra expense to some growers. On one field in northeast Iowa, the participating grower noted that an average of one ripper shank shear bolt had to be replaced on every pass across the field.
* Driving across the tilled area, even at harvest the next fall, was more challenging because ripping left the soil surface loose.
* Some growers believed that the planter may have run too deep in the tilled strips, resulting in slower, less uniform emergence and lower yields than in the untilled strips where the surface was more firm.
* While growers liked seeing the ripper operate and the loose soil surface it left behind, after two years doing these trials, most determined that the best application for deep ripping was only on headlands or areas with a confirmed compaction problem.
For more information: "Two years of summary reports are posted at the On-Farm Network website," says Blackmer. "For more information, email us your questions or telephone number and we'll get back to you as soon as possible."