Nitrogen fertilizer and landscape position impacts on CO₂ and CH₄ fluxes from a landscape seeded to switchgrass

Abstract

This study was conducted to evaluate the impacts of N fertilizer and landscape position on carbon dioxide (CO 2 ) and methane (CH 4 ) fluxes from a US Northern Great Plains landscape seeded to switchgrass (Panicum virgatum L.). The experimental design included three N levels (low, 0 kg N ha À1; medium, 56 kg N ha À1; and high, 112 kg N ha À1) replicated four times. The experiment was repeated at shoulder and footslope positions. Soil CO 2 and CH 4 fluxes were monitored once every 2 weeks from May 2010 to October 2012. The CO 2 fluxes were 40% higher at the footslope than the shoulder landscape position, and CH 4 fluxes were similar in both landscape positions. Soil CO 2 and CH 4 fluxes averaged over the sampling dates were not impacted by N rates. Seasonal variations showed highest CO 2 release and CH 4 uptake in summer and fall, likely due to warmer and moist soil conditions. Higher CH 4 release was observed in winter possibly due to increased anaerobic conditions. However, year to year (2010-2012) variations in soil CO 2 and CH 4 fluxes were more pronounced than the variations due to the impact of landscape positions and N rates. Drought conditions reported in 2012, with higher annual temperature and lower soil moisture than long-term average, resulted in higher summer and fall CO 2 fluxes (between 1.3 and 3 times) than in 2011 and 2010. These conditions also promoted a net CH 4 uptake in 2012 in comparison to 2010 when there was net CH 4 release. Results from this study conclude that landscape positions, air temperature, and soil moisture content strongly influenced soil CO 2 fluxes, whereas soil moisture impacted the direction of CH 4 fluxes (uptake or release). However, a comprehensive life cycle analysis would be appropriate to evaluate environmental impacts associated with switchgrass production under local environmental conditions.

Switchgrass Biomass Quality as Affected by Nitrogen Rate, Harvest Time, and Storage

“…The average precipitation in 2011 was 6.5% lower than the long-term annual average precipitation, but in 2010 it was 17.5% higher than the long-term annual average precipitation (Mbonimpa et al, 2015). Because the second season encountered drier conditions, concentrations of all of the mineral elements, except K, were less than were those of the first season (Tables 2 and 3).…”

“…Because the second growing season (2011-2012) encountered drier conditions compared with the first growing season (2010-2011) (Mbonimpa et al, 2015), the concentrations of …”

Dedicated Energy Crops and Crop Residues for Bioenergy Feedstocks in the Central and Eastern USA

“…Growing season soil CO 2 and CH 4 emissions from switchgrass in the Northern Great Plains are not impacted by fertilizer N rates [93,94], but higher N inputs can increase yield as well as soil N 2 O emissions [93]. In contrast, correlations between N rate and soil N 2 O emissions were obscured by annual variability in weather and soils in a multi-year evaluation of corn stover removal across nine sites in Iowa, Indiana, Minnesota, Nebraska, and South Dakota.…”

Effect of long-term differential application of inorganic fertilizers and manure on soil CO₂ emissions

“…Further, soil CO 2 emissions have found to be regulated by soil temperature and moisture (Peng et al 2011, Allaire et al 2012, Dhadli et al 2015. Soil moisture coupled with soil temperature and other soil-atmospheric interactions had been found to greatly affect soil CO 2 emissions, and an increase for shorter period after N application was also recorded (Dhadli et al 2015, Mbonimpa et al 2015. Relationship of CO 2 emission with soil C and N status.…”

“…Conflicting results were reported about the changes in soil organic carbon (OC) due to use of inorganic fertilizers under intensive agriculture. Application of fertilizers, along with tillage and crop residue management practices, influence emissions of greenhouse gases (GHG) from agricultural soils (Adviento-Borbe et al 2010, Mbonimpa et al 2015, Dhadli et al 2016. Further, cropping systems can influence CO 2 emission by affecting the quality and quantity of C returned to the soil as root biomass or as straw incorporation or mulching (Mapanda et al 2011, Gong et al 2012, Ding et al 2014).…”