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Quantifying intra-seasonal switchgrass changes allows for simulating productivity trade-offs

 

Renewable fuel standards put in place by the federal government set requirements that sustainable biomass sources be used for ethanol production. Switchgrass is a native, perennial prairie grass that requires minimal fertilizer inputs and produces high biomass yields on marginal lands. However, data on seasonal trends in plant growth, composition, and nutrient removal are incomplete for developing models for predicting optimal harvest times of switchgrass for bioenergy.

In a paper recently published in Agronomy Journal, a research team investigated the seasonal changes in feedstock quality and quantity, as well as soil and tissue moisture. Researchers found that biomass accumulation peaked in late summer, with yields decreasing by at least 26% from September to February. Biomass moisture content declined to levels appropriate for direct storage by mid-December. Desirable feedstock composition traits and a reduction in nutrient removal were observed by late fall.

Consequently, delaying harvests to late fall or winter will reduce fertilizer replacement the following year and improve energy density and moisture content of biomass; however, a trade-off in yield will occur. Quantifying these intra-seasonal changes allows for simulating productivity trade-offs and applying those to economic and environmental analyses.

 

Read the full open access paper in Agronomy Journal