COS 1-2 - An Evaluation of Surface Reflectivity for Candidate Bioenergy Crops

Abstract: A poorly understood aspect within climate change is the biogeophysical changes associated with surface-induced albedo, which can affect the energy budget and subsequently cause localized warming/cooling of the climate. Increasing the albedo of common candidate croplands could provide a higher surface reflectance, and help mitigate against global warming. These rapidly expanding biofuel crops have been proposed as an alternative to fossil fuels, however when a Life Cycle Analysis (LCA) of these crops analyzing the potential effects of changes in albedo are rarely included. This is mainly due to the lack of knowledge about how different crop species, management techniques and seasonality may affect albedo and consequently the warming/cooling potential of these crops.

To advance our understanding we established measurements of surface reflectivity on several biofuel crop species. Two maize–soybean–winter wheat (CSW) rotations were designated as our annual crop treatments, a monoculture switchgrass crop, and two polycultures of early successional and restored prairie grasslands as perennial candidates. Over four years (2019-2022), we examined the effects of several factors including crop-species, agronomic management, seasonality, and plant phenology on the variation in surface reflectivity.

Our results showed that albedo differences were highly related to crop species, agronomic management over multiple temporal scales. Albedo was higher in perennial crops of switchgrass (0.180) and early successional (0.171). Conventional tillage exhibited differences in surface reflectivity (0.175), compared to its reduced-input landscape (0.167). This work expects to demonstrate how diverse ecosystems and modern agricultural practices can affect surface reflectivity, and provide methods for reducing GHG emission at localized scales.