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. In fact, as a graduate student I worked part of one summer at the farm.
The 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 Sharpsburg, 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). 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.
Each year the yields are published corrected to standard moisture content for each crop. This year, being a drought year, I was curious how Paul Jasa’s corn and beans did.
With the dryland corn study Plow, disk, disk was 81.6 bu/ac; Chisel, disk once was 87.5 bu/ac; Disk twice was 86.3 bu/ac; Disk once with a cover crop 81.6 bu/ac; No-till with a cover crop 85.1 bu/ac; and Continuous No-till 92.1 bu/ac. Row crop cultivation was performed on the cover crop treatment for 15 years from 1981 to 2006. This may explain some of the yield difference compared to the continuous no-till treatment without a cover crop.
With the dryland soybean yields at the Rogers Memorial Farm the Plow, disk twice treatment yielded 32.7 bu/ac; Chisel, disk once 33.7 bu/ac; Disk twice 38.0 bu/ac; Disk with cover crop 34.9 bu/ac; No-till with cover crop 42.2 bu/ac and Continuous No-till 41.2 bu/acre.
With $15 soybeans, continuous no-till on the Rogers farm grossed $127 an acre more than disking twice before planting. With $7.50 corn, continuous no-till grossed $43.50 an acre more than disking twice before planting. With no-till, the improved soil structure and moisture conserving residue cover makes more water available for a thirsty crop by improving infiltration, increasing soil carbon and decreasing evaporation from the soil surface.
With five years of cover crop yield results with corn and beans, will the cover crop treatment catch up to the continuous no-till plot yields? If it can, this study proves it will take longer than five years when using cereal winter rye and rye/winter pea mixture.