Comparison of Soil Responses to Long-Term Fertilization and Short-Term Nitrogen and Carbon Amendments in Miscanthus and Corn
Authors:
Adina Howe1,2* ([email protected]), Jaejin Lee1,2, Paul Villanueva1,2, Kate Glanville1,2, Andy Vanloocke1,2, Wendy Yang1,3, Angela Kent1,3, Marshall McDaniel1,2, Steven Hall2, Andrew Leakey1
Institutions:
1DOE Center for Advanced Bioenergy and Bioproducts Innovation; 2Iowa State University; 3University of Illinois Urbana-Champaign
URLs:
Goals
This work aims to shed light on the impacts of long-term and short-term nitrogen (N) inputs and of Miscanthus x giganteus (miscanthus) on soil responses. Greenhouse gas emissions, net nitrogen mineralization, and microbial community nitrogen cycling genes were compared between miscanthus and maize soils with varying legacies of N fertilization and with contemporary N amendments.
Abstract
Understanding the role of bioenergy crops in carbon and nitrogen dynamics is crucial for sustainable production of biofuels and bioproducts. Miscanthus x giganteus, a promising perennial biomass crop, is favored due to its high biomass yields compared to annual crops like maize. However, the effects of miscanthus on carbon sequestration and reducing nitrogen leaching and emissions compared to corn have been inconsistent. In this study, the team directly compared soils from miscanthus and maize fields for greenhouse gas emissions, net nitrogen mineralization, and the abundance of microbial nitrogen cycling genes over a 150-day soil incubation period. Soils were obtained from miscanthus and corn fields at the end of the growing season for incubation experiments. The team evaluated these incubation soil responses to compare the impacts of legacies of fertilization to the responses to contemporary amendments. The results revealed that cumulative soil nitrous oxide (N2O) emissions increased during the incubation, with miscanthus producing significantly greater N2O than corn. Additionally, higher fertilization levels resulted in greater N2O production, with N amendment showing a larger effect than C amendment. Net N mineralization was significantly affected by crop type and amendment but not historical fertilization. Microbial processes play a crucial role in determining soil N availability. The team observed no significant differences in total copies of the 16S rRNA gene between crops, historical fertilization treatments, or amendments. However, the abundance of specific bacterial genes involved in N cycling varied, with higher copies of genes associated with nitrification in miscanthus soils and an increase with historical fertilization levels. Genes encoding nitric oxide reductases generally decreased with higher N fertilization levels. The team found that contemporary N addition increased N2O production as expected, but the larger difference in N2O production was explained by the legacy of fertilization. This trend was observed in both corn and miscanthus but significantly supported only in miscanthus, indicating a unique response of miscanthus to fertilization legacy. Overall, the results suggest that microbial processes in miscanthus soils differ significantly from maize and emphasize the importance of considering previous land management history when evaluating the contribution of miscanthus and bioenergy crops to N balances.
Funding Information
This research was supported by the DOE Office of Science, BER Program, grant no. DE-SC0018420.