Long-term No-till Outyields Tilled Comparisons

Long-term No-till Outyields Tilled Comparisons

December 14, 2007

A tillage study was established in 1981 at the University of Nebraska Rogers Memorial Farm, 10 miles east of Lincoln, to gain experience with various tillage systems. These dryland research and demonstration plots, started as a 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. In 2005, one set of plots was switched to a corn/soybean rotation. This year, soybeans were planted into grain sorghum residue and corn was planted into soybean residue.

Table 1. 2007 grain yields for various tillage systems at the dryland Rogers Memorial Farm.
Yield, bu/ac
Tillage System
No-till *
*Cultivated from 1981 to 2006 - not cultivated in 2007.

The yields from 2007 showed that the crops did quite well in a year without much rainfall in the middle of the growing season. The season started with a full soil moisture profile and the field received about 5 inches of rain in May. Then it turned dry in June and July, with only about 1 inch and 2 inches of rain, respectively. From August 1 until September 18 (crop maturity), an additional 5.8 inches of rain fell, helping the soybeans but coming a little late for the corn. The no-till plots had the highest yields and the best profitability as they didn't have any tillage costs (see Table 1).

Historically, row crop cultivation has been used for weed control and these plots included no-till with and without cultivation from 1981 until 2006. In 2007 the plots were not cultivated and it was interesting to note the effect of previous cultivation on yields, almost the same as doing tillage this year. As many producers are doing, postemerge herbicides have been used on these plots the past several years in combination with an early preplant application, making row crop cultivation unnecessary. In the previous years, row crop cultivation did not increase yields unless there was severe weed competition not controlled by herbicides.

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. After the 2007 harvest, a cereal rye cover crop was drilled into one of the no-till treatments (no-till cultivated in the past) and one of the disk treatments (disk). This use of cover crops will continue and add a new dimension to the tillage study, looking at the effects of the extra roots and biomass in the soil system.

Paul Jasa
Extension Engineer

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A field of corn.