by Jenny Rees, UNL Extension
Amelioration strategies after corn residue removal: The last two weeks I've shared research results regarding corn stover removal and impacts on nutrient, soil erosion, soil organic carbon and the succeeding crop yields. Most of the studies, including the ones I write about here, are continuous corn and stover removal each year to determine the potential worst case scenarios and recommendations for producers. Some have asked how amelioration practices such as cover crops and adding manure affect nutrient and soil properties when corn stover is removed. More research has been published in the past year with research ongoing. A key factor when looking at these research results is to know what was the soil type in the study; silt loam soils and irrigated situations appear to be more resilient than sandy ones and non-irrigated environments.
One study from 2013-2016 looked at soil property changes and corn yield with five different corn residue removal rates (0, 25, 50, 75 and 100 percent) and the addition of three cover crop treatments (no cover; early cereal rye termination of 2-3 weeks prior to corn planting; late cereal rye termination mostly occurring within 10 days after corn was planted). This was studied in a non-irrigated (Rogers Memorial Farm near Lincoln) and an irrigated environment (South Central Ag Lab near Clay Center) both in no-till continuous corn systems. Both locations had silt loam soils. Residue was removed in mid to late October each year at each location and cereal rye cover crop treatments were drilled shortly thereafter. The cover crops were not irrigated for establishment or additional growth.
For soil properties, wet aggregate stability (to determine potential for water erosion), concentrations of particulate organic matter, soil organic carbon and total soil N after three years of management were measured.
There was a reduction in size of wet aggregate stability in the non-irrigated site over three years with complete residue removal suggesting the potential for increased water erosion. Irrigated soils may be more resilient in their response to wet aggregate stability to residue removal suggesting that more residue could be removed from irrigated sites compared to non-irrigated sites in the short term. Early termination appeared to have no effect on offsetting the corn residue removal effects on water erosion potential. Later termination of the cover crop resulted in increase of wet aggregate stability at both locations. On average, later cover crop termination resulted in 0.7 tons per acre biomass compared to 0.2 tons per acre under early termination. Increased cover crop biomass occurred where residue was removed compared to where it was not. The authors suggest that a cover crop biomass yield above 0.4 tons per acre may offset the water erosion potential effects of crop residue removal.
Soil organic carbon and total nitrogen concentrations weren't significantly affected by either residue removal or timing of cover crop termination in either site after three years. This suggests that in the short term, even high rates of residue removal do not reduce these concentrations. Addition of cover crops after residue removal at both sites increased soil organic carbon concentrations. A 13.5 percent increase in particulate organic carbon was observed with later termination over early termination and the control treatments at the irrigated site at the 1 foot depth. There were no effects at the 2 foot depth.
Residue removal and cover crop termination date did not affect corn yield when all three years were combined. There were individual year and location effects on corn yield suggesting these effects may be year and site-specific. It was noted corn was shorter in the non-irrigated field at 0 percent residue removal vs. 50 100 percent residue removal early in the season; however, the heights were consistent by tasseling. This is similar to the irrigated field in which corn was taller early in the season at the 100 percent residue removal compared to 0 and 50 percent with similar heights for all residue removal treatments by tasseling. Residue removal and cover crop termination date also didn't affect the amount of residue the corn plants produced each year. The overall conclusion of the study suggested that higher than the suggested 30-50 percent of residue removed may be possible in some soils (such as silt loam) when cover crops are used to help ameliorate the effects of removal.
Another Nebraska study near Bellwood looked at effects of aerial interseeded cereal rye vs. no cover into a standing corn crop in late August and early September from 2013-2015. Corn was harvested as high moisture corn followed by residue removal treatments of 71 percent corn residue removal or no removal on a sandy loam soil. This study was conducted on strip-till, irrigated, continuous corn. They found the treatments did not affect fertility properties or subsequent corn yield. However, increased wind erosion was noted by harvesting 71 percent of the residue on sandy loam soils compared to no residue harvest or addition of the rye cover crop. The addition of the rye cover crop did not significantly impact soil properties on a sandy loam soil within three years but it tended to reduce soil erosion. It was also noted that biomass production by aerially interseeding the rye into standing corn vs. the authors' other studies of drilling the rye after harvest didn't appear to increase cover crop biomass in spite of being seeded two months earlier. This could be because of variability of establishment and biomass production of the aerially interseeded rye each year, which may have also been a limitation on impacting soil properties in a more positive way.
A five year study at UNL's South Central Ag Lab near Clay Center looked at corn residue removal and interactions of irrigation rate (full or limited to 60 percent), fertilizer management (112 lbs N/ac vs. 180 lbs N/ac) and amelioration practices of winter cover crop, manure, or no amelioration practice on continuous irrigated corn yield. Cereal rye was drilled in late October after harvest at a rate of 100 lbs per acre and was terminated two weeks prior to planting corn. For the manure treatment, sheep or cattle manure was applied following corn and stover harvest in the fall every two years based on phosphorus removal. Statistical yield increases occurred with stover removal and the 180 lbs N/ac nitrogen rate suggesting these yield increases could be expected in irrigated, no-till, continuous corn systems where residue was removed on silt-loam soils. There were no statistical yield differences based on irrigation amounts nor type of amelioration practice. Addition of cover crop or manure as amelioration practices did increase two types of nitrogen efficiency measured in the study while maintaining soil organic carbon and yield and reducing soil erosion.
My conclusion: These Nebraska studies suggest the addition of a cover crop or manure after corn stover removal does not negatively impact the subsequent corn yield where water is not limiting and aids in reducing erosion on all soil types. Higher amounts of cover crop biomass (over 0.4 tons per acre) may be necessary to positively affect soil properties in the top foot in the short-term of 3-5 years. Studies are ongoing to determine additional and consistent impacts over time. An economic component of amelioration practices would also be beneficial.
Grain marketing workshop: Marketing grain may not be your favorite thing or your strength. Upcoming grain marketing workshops in Beatrice at the Gage County Extension Office (Dec. 11) and the 4-H Building in York (Dec. 12) are designed to help understand futures and options to protect farmers from adverse market movements. Participants will use a computer simulator (computers are provided) to practice, based on previous, actual market years. Participants will then leave the workshop having programmed a marketing plan into their smartphone using the Grain Marketing Plan smartphone app. RSVP to email@example.com if you plan to attend. There is no charge for the workshop, lunch is provided, and it will run from 9:30 a.m. to 3 p.m.
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Letter to the
By Sen. John Kuehn,
Since 1790, the federal government has conducted the decennial census every 10 years. Originally established as a mere head count of residents of each of the states for the purpose of apportioning members of the U.S. House of Representatives, the census has grown into a comprehensive effort that collects data on a number of characteristics of Americans. That information influences distribution of federal funds based on population as well as serves as the major federal data set for policy analysis during the next 10 years.
In the year following each decennial census, states use the population information collected to evaluate the population residing in different electoral districts to determine if they contain relatively equal numbers. These include not only Nebraska's three members of the U.S. House of Representatives, but more significantly legislative districts for representation in state government, as well as districts for the
University of Nebraska Board of Regents, Public Service Commission and state board of education. As shifts in population occur, apportioning equal numbers of voters into each district may require redrawing district boundaries. This process is known as redistricting.
Residents of District 38 are familiar with the consequences of redistricting. In 2011, LB 703 created new boundaries for the district following the 2010 census. Kearney County was moved into the district and Harlan County was moved into District 44. Clay County has also moved among different legislative districts through different iterations of legislative redistricting.
With the shift in population to Douglas, Sarpy and Lancaster counties, the redistricting process will continue to have significant implications for representation of rural Nebraska in the legislature.
In 2011, the movement of District 49 from western Nebraska to Gretna created an important change in the legislature. Of the 49 seats, 25 are now held by representatives of the Omaha and Lincoln urban areas. Current population projections would indicate two additional seats will be shifted away from rural Nebraska to the Omaha and Lincoln area. That magnifies the urban dominance in the Nebraska Legislature from a simple majority to a 27-22 split.
While most rural states also face this population shift, the impact on the representation of rural areas in state government is not as extreme. In a two-house state legislature, the population shifts impact rural representation in the state House of Representatives, while geographic representation remains in the senate. As the only unicameral in the nation, the loss of legislative seats in the single legislative chamber means a direct loss of representation in state government.
The consequences of this political shift can be enormous for rural Nebraskans. There is no better example than the dysfunctional school funding system that has left rural districts paying for public education almost exclusively with local property taxes, while urban districts consume almost a billion dollars of state equalization aid. Appeals to fairness by rural senators and rural citizen groups have fallen on deaf ears of urban senators, whose support is required to restore equity to the system. The problem has been recognized for almost a decade, with little action to resolve it.
The Nebraska Constitution specifically assigns the responsibility for apportionment and redistricting with the Nebraska Legislature. In advance of the anticipated redistricting process in 2021, several legislative proposals have emerged that attempt to divert the redistricting process to unelected commissions based on party registration. I opposed the first redistricting bill, LB 580, to come to the floor for a vote in 2016. Two additional bills, LB 216 and LB 653, were introduced in this past session and remain in executive committee, of which I am vice chairman. I oppose the creation of any unelected advisory committee for redistricting on a partisan basis, and thus will not support either current bill for advancement to general file.
My experience in the Nebraska Legislature has reinforced the common expression that Nebraska's greatest divides are not by party, but rather rural versus urban. Low commodity prices have had a direct and significant impact on state revenues, demonstrating that rural Nebraska remains the economic engine of our state and state
government. Even with this reality, critical rural needs, such as school funding reform, remain unaddressed despite years of focus and discussion.
Rural Nebraskans should carefully watch and evaluate the redistricting process that will be taking shape in the coming years. To date the focus has been on concerns of political parties, not on the impact of the accelerating shift of representation to urban areas. Voters of District 38 should get engaged. The nature of their representation in state government rests with the outcome.