A tillage study was established in 1981 at the University of Nebraska Rogers Memorial Farm (RMF), 10 miles east of Lincoln, to gain experience with various tillage systems. These dryland research and demonstration plots are showing that long-term continuous no-till builds soil structure, usually has the highest yield, and is the most profitable. Located on a sloping, upland silty clay loam soil, they were started as a soybean/grain sorghum rotation common to southeast Nebraska at the time.
In 2005, one set of plots was switched to a corn/soybean rotation. The other set was switched to corn/soybeans in 2007. Since 2007, a cover crop has been drilled after harvest on both a tilled (single disk in the past) and no-till treatment (no-till with cultivation in the past). The yields shown below are combine harvest, weighed, and corrected to standard moisture content for each crop.
|Plow, disk, disk||23.2||44.6||10.9||38.2||65.3||48.3||43.2||48.4|
|* Severe hail on August 28, 2002 reduced yields greatly. # None of the plots were cultivated in 2007. It is interesting to note the yield reduction on the no-till plot that was cultivated in the past (1981-2006).|
|Plow, disk, disk||61.2||120.0||34.8||123.0||152.8||92.1|
|* Severe hail on August 28, 2002 reduced yields greatly. # Sandburs invaded the plots in 2004, tracked in from borders. The row crop cultivation in the other treatments reduced the resulting weed competition. The no-till yield was 146.1 bu/A for the rep without the sandbur control problems (away from the borders).|
|Plow, disk, disk||183.6||132.4|
|* None of the plots were cultivated in 2007. It is interesting to note the yield reduction on the no-till plot that was cultivated in the past (1981-2006).|
Cover Crop Added to Existing Study
Since 2007, a cover crop has been no-till drilled after the harvest of both the corn and the soybeans. Cereal rye was used as a single species cover crop in the falls of 2007 to 2009. Cereal rye and winter peas have been used in a 50/50 blend since the fall of 2010 as the cover crop.
In the spring, the growing cover crop in the no-till with cover crop treatment for corn is sprayed with glyphosate or Lumax about two weeks before planting. About the same time, a single pass of a tandem disk is used on the growing cover crop in the disk with cover crop treatment for both the corn and the soybeans. A second pass with the disk is made a couple of days before planting to finish seedbed preparation and kill any remaining cover crop.
The growing cover crop in the no-till with cover crop treatment for soybeans is sprayed with glyphosate either before planting or after the beans emerge, but before the rye heads. Above is a photo taken shortly before planting the soybeans into the corn residue showing the cereal rye cover crop. For both crops, a residual herbicide with 2,4-D for winter annual broadleaf weed control (no glyphosate burndown) is applied to all the tillage treatments several weeks before planting. Row crop cultivation is no longer used on any of the treatments.
|Plow, disk, disk||214.1||214.4||198.2||190.1||81.6||140.7|
|Disk w/cover crop||211.1||214.0||202.9||188.9||81.6||150.1|
|No-till w/cover crop*||214.3||209.8||205.2||190.1||85.1||160.7|
|* Row crop cultivation was performed on this treatment from 1981 to 2006. This may explain some of the yield difference compared to the continuous no-till treatment without a cover crop. (See the 2007 yield results above.) # Severe drought|
|Plow, disk, disk||49.0||48.2||57.5||44.6||32.7||50.1|
|Disk w/cover crop||50.2||49.0||55.2||41.8||34.9||47.7|
|No-till w/cover crop*||54.4||54.0||51.4||47.9||42.2||55.2|
|* Row crop cultivation was performed on this treatment from 1981 to 2006. # Severe drought|