State study tracks conservation practices after corn silage harvest
BRILLION – With Wisconsin's corn silage harvest now on the horizon, landowners and renters often have concerns about soil conservation and water quality on the land which had been covered by a corn stand for several previous months.
How the growing of a followup cover crop, particularly cereal rye, can address those concerns has been the subject of a six-year study in one-half acre plots on leased land near Arlington. The results of six management scenarios at that site were reported by University of Wisconsin Extension Service soil scientist Francisco Arriaga at the Calumet County Forage Council's 2019 field day.
Various cropping scenarios with corn for silage, alfalfa, and cereal combined with minimum to full tillage were conducted, Arriaga reported. In addition to the natural precipitation at the site, rainfall simulations of 3.25 inches per hour were carried out in June and October of 2016 and April of 2017.
Rainfall test findings
What stood out in all three rainfall simulations was the greater loss of bio-available phosphorus in the plots where cereal rye was not in that year's crop rotation, Arriaga pointed out. “Even the loss of phosphorus from a half acre is a big one.”
Phosphorus runoff losses in the plots where cereal rye was not part of the crop rotation were close to .4 pounds per acre in June of 2016, 1.1 pounds in October of 2016, and 1.3 pounds in April of 2017. Even with the rye cover crop, those losses hit .2, 1, and .35 pounds respectively.
When both cereal rye and corn were harvested in a given year, the total forage yield was higher than if only the corn was grown, Arriaga noted. In 2017, for instance, the per acre ryelage dry matter yield was 2.8 tons while the dry corn silage yields were 6.4 tons in a no tillage plot and 7.9 tons with conventional tillage. For all the years, forage yields increased by an average of 4.6 percent when cereal rye was part of the year's harvest rather than being terminated to accommodate the corn planting.
Depending on the tillage and other factors, there were year to year differences in the corn silage and total forage yields but there was nothing that raised great concern, Arriaga observed.
To a question about the economics of the varying practices, he said those numbers will be “the next step” in the analysis of the project, which is probably in its last year after initial funding by the former Monsanto Company, he stated.
Value of manure
“Manure is fantastic for soil health” is Arriaga's assessment of the testing conducted at the special Arlington plot and in his other research ventures. Among the several soil health testing methods, he prefers the Cornell test over the more recently promoted Haney method.
The soil health tests consider soil particle aggregation, penetrometer readings, water infiltration and penetration, bacteria, fungi, and other biological traits, Arriaga explained. In addition to its plant nutrient value, manure is a great contributor of the building of organic matter in the soil, he emphasized.
At the cereal rye and corn silage plot, 10,000 gallons of liquid dairy manure were injected per acre between the harvest of the corn silage and the seeding of cereal rye and some nitrogen was applied in the spring, Arriaga indicated. One change in 2018 was application of the liquid manure after the cereal rye was planted, he noted.
Cover crop choices
When considering the array of cover crop choices, be aware of differences between them in both above ground and below ground biological mass, Arriaga advised. Because of the role of the plant roots, be sure to include at least one species with fibrous roots in any cover crop mix, he said.
“Taproot plants offer less protection against soil erosion,” Arriaga stressed. “They help with breaking a soil hard pan but I've also seen soil scouring around radish plants.”
Arriaga can be reached by e-mail to firstname.lastname@example.org or by phone to (608) 263-3913.