Greenhouse gases mitigation by nitrogen fertilization of switchgrass

Nitrogen fertilization is an important management practice for switchgrass biomass production and feedstock quality.

There is still a lack of information regarding biomass yield and net greenhouse gases impacts on nitrogen fertilization of switchgrass, particularly in the Upper Great Lakes Region. One study was conducted at the Michigan State University (MSU) Upper Peninsula Research Center at Chatham to evaluate the effects of nitrogen fertilization on greenhouse gas emissions and biomass production of switchgrass bioenergy crop.

There were three nitrogen fertilization treatments: 0 (control), 50, and 100 pounds Nitrogen (N) per acre per year and urea (46 percent N). Soil fluxes of CO2, N2O and CH4 were measured every two weeks using static chambers. The field was no-till planted with switchgrass variety “Cave-in-Rock” in 2008 and seeding rate was eight pounds of pure live seed (based on germination rate and purity) per acre. Nitrogen fertilization greatly stimulated CO2 uptake by switchgrass, resulting in 1.5- (3.2 dry matter tons per acre) and 2.5-fold (5.3 dry matter tons per acre) increase in biomass yield in 50 and 100 pounds N treatments, respectively as compared to the control treatment (2.2 dry matter tons per acre).

This study also showed that nitrogen fertilization improved the greenhouses benefits by 1.16 tons per acre per year for 50 pounds N treatment and 4.2 tons per acre per year for 100 pounds N treatment as CO2 equivalents relative to the control treatment. Results suggest that nitrogen fertilization of switchgrass in this region could reduce (15 – 50 percent) of the land base needed for bioenergy production and decrease pressure on land for food and forage crop production.

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