Herbaceous perennial biomass production on frequently saturated marginal soils: Influence on N2O emissions and shallow groundwater. (March 2019)

• Record Type: Journal Article
• Authors: Rau, Benjamin M.; Adler, Paul R.; Dell, Curtis J.; Saha, Debasish; Kemanian, Armen R.
• Is Part Of: Biomass and bioenergy. Volume 122(2019)
• Page Start: 90
• Page End: 98
• Publication Date: 2019-03
• Subjects: Biomass -- Switchgrass -- Miscanthus -- Marginal soils -- N2O -- Water quality; Biomass energy -- Periodicals; Biomass -- Periodicals; Energy-Generating Resources -- Periodicals; Bioénergie -- Périodiques; 333.9539
• DOI: 10.1016/j.biombioe.2019.01.023
• Languages: English
• ISSNs: 0961-9534

Abstract

Abstract: Warm season perennial grasses grown for biomass have been suggested as alternative cropping systems on marginal soils to increase farm profit, reduce nitrous oxide (N2 O) emissions, and improve water quality. The objectives of this study were to determine: 1) how warm season perennial grasses, switchgrass ( Panicum virgatum ) and Miscanthus ( Miscanthus x giganteus ), compare to cool season grasses as streamside buffers on poorly drained marginal soils 2) if inorganic or organic nutrient additions improve biomass yield and affect environmental outcomes? 3) which soil variables influence N2 O emissions in situ ? We measured soil N2 O emissions, soil solution nitrate (NO3 − ), ammonium (NH4 + ), O2, moisture, and temperature, along with shallow groundwater NH4 +, NO3 −, and ortho-phosphate during two growing seasons (2012–2013). N2 O emissions were similar across unfertilized warm season grasses and cool season grasses. However, when switchgrass was fertilized with ammonium sulfate or broiler manure, N2 O emissions increased significantly. N2 O emissions were weakly correlated with soil solution NO3 − concentrations and water filled pore space. Shallow groundwater N was elevated under switchgrass fertilized with ammonium sulfate, broiler manure, and when grown with the legume ( Desmodium canadense ) when compared to unfertilized switchgrass, Miscanthus, and cool season grasses. In 2013 dry aboveground biomass production did not differ among switchgrass treatments which averaged 10 Mg ha. Biomass production was significantly higher for Miscanthus (18.5 Mg ha). The results indicate that unfertilized switchgrass and Miscanthus are as effective as cool season grasses at mitigating N2 O emissions and improving water quality, and that Miscanthus has potential production advantages over switchgrass grown on frequently saturated soils. Highlights: Fertilizing with 50 kg N increased N2 O emissions by 50–70% over controls on poorly drained soils. N2O emissions peaked after fertilization and subsequent rainfall that increased WFPS to >60%. Although WFPS exceeded 60%, soil O2 remained >15% during peak N2 O emissions. Peak N2 O emissions were short lived and persisted less than 7 days. Fertilization or growing Switchgrass with legumes increased groundwater N > 40% over controls, but was well below USEPA limits