November 21, 2006

In order to gain management experience and production data, a long-term tillage system study was established in 1981 at the University of Nebraska Rogers Memorial Farm, 10 miles east of Lincoln. These research and demonstration plots, started as a dryland soybean/grain sorghum rotation common to southeast Nebraska at the time, are showing that long-term no-till builds soil structure, usually has the highest yield, and is the most profitable. This year, the soybeans were planted into corn residue as the one set of the plots was changed to a corn/soybean rotation in 2005.

The soybean and grain sorghum yields from 2006 showed that no-till did quite well in a year with little rainfall early in the growing season. The season started with almost a full soil moisture profile from the 7.75 inches of precipitation that fell since the last harvest; however, an on-site weather station recorded only 3.4 inches of rain from May 1 to August 1, far below average. From August 1 until September 10, an additional 5.5 inches of rain fell, really helping the soybeans but coming a little late for the grain sorghum. As such, soybean yields were above average for the conservation tillage systems and grain sorghum yields were below the long-term averages for this study.

It was observed that the residue on the soil surface for the conservation tillage systems reduced evaporation and kept the soil cooler during the heat of the summer. Even row crop cultivation of the no-till reduced the yields, especially for the grain sorghum, as the soil surface was loosened and some residue was lost. However, it was interesting to note a "greening up" of the no-till soybeans immediately following cultivation, just as the old timers used to say about a crop responding to cultivation. Yet there was no yield increase to justify the cost of cultivation.

The continued use of no-till has improved soil structure and protects the soil surface with residue. With less crusting and reduced runoff, more soil moisture is available for the crop, resulting in higher yields.

Paul Jasa
Extension Engineer