Improving Input Use Efficiency in High-Yielding Corn Systems
The Crop Physiology Laboratory at UIUC has conducted experiments over the last 20 years to identify the principle factors that result in increased corn yields. The seven factors that were found to have the greatest impact on corn grain yields are weather, nitrogen, hybrid, previous crop, plant population, tillage, and growth regulators. Based on this information, an omission plot experimental design was created to test five of the identified factors (nitrogen, other fertility, genetic traits, population, and growth regulators) for their individual and cumulative effects on yield.
In 2011, we added three more factors (crop rotation, residue management, and reduced tillage) to the omission plot experimental design in an effort to identify conservation practices that maintain or improve yields in high-yielding corn production systems. Compared to a corn monoculture, corn-soybean rotations reduce N fertilizer application, reduce pest pressure, and are generally thought to promote a more diverse soil biological community to reduce disease susceptibility and serve as a reservoir for gene conservation. Research and anecdotal evidence have also shown that corn following soybean generally produce greater yields than following corn. Research by the Crop Physiology Lab indicates that the primary agent of yield reduction in corn following corn is corn residue, although the mechanism is not fully understood. Although frequently considered a poor practice for soil quality considerations, partial stover removal can be performed without degrading soil quality or reducing soil organic matter when used in the appropriate environment and with proper management (Fronning et al. 2008). Johnson et al. (2007) have also shown that compared to aboveground corn stover, corn roots are a more long-term, stable source of carbon and, thus, better for soil carbon sequestration than stover. We will quantify and compare root production in the high-yield vs. traditional environments to determine the additional biomass added as root biomass in the high-yield environment and equate that value with an allowable stover harvest value. We propose that stover removal in the high-yield corn environment can not only be performed in a sustainable manner, but that the compounded benefit of using stover for biofuel production or as an animal feed source makes good use of a secondary agricultural output in a value-added manner. In addition to testing the sustainability of removing corn stover in corn-corn systems, we will also assess if removing stover will reduce or eliminate the corn-corn yield penalty. Strip tillage is a relatively new reduced tillage system that protects soil from erosion, retains plant-available water later in the growing season, and allows banding of fertilizers for more efficient plant uptake and reduced erosional losses associated with broadcast fertilization.