Impact of crop residue removal on crop production, feedstock quality, and theoretical ethanol production in the Mid-Atlantic United States

Cellulosic biomass-to-bioenergy systems provide fuel, reduce emissions, and offer economic benefits. Corn (Zea mays L.) and wheat (Triticum aestivum L.) residues could be used as feedstocks for biofuel production. However, the impact of residue removal on crop productivity in the Mid-Atlantic region has not been thoroughly assessed. A trial was conducted to assess crop yield and quality response to different biomass retention rates in grain cropping systems during 2015–2017. Various combinations of corn stover (0–10 Mg ha⁻¹) and wheat straw (0–3 Mg ha⁻¹) were applied in a corn–wheat/soybean [Glycine max (L.) Merr.] rotation in New Kent, VA. In Blacksburg, VA, corn stover (0–20 Mg ha⁻¹) was applied in the continuous corn system. Residues were applied after grain harvest over two production cycles for each system. Residue retention showed no significant impact on grain or crop residue yields or nutrient uptake in either system. Treatment minimally impacted feedstock quality, except wheat straw's sulfur (S) concentration, optimized at around 70% retention in New Kent. Theoretical ethanol potential (TEP) and yield remained unaffected by total residue rates in New Kent. In Blacksburg, over 2 years, a minimum TEP for corn stover corresponded to a retention rate of approximately 30%. A retention rate of more than 30% increased TEP, likely due to improved feedstock quality. Nutrient replacement costs for primary macronutrients and S uptake ranged from $18.3 to $36.9 ha⁻¹ for corn stover and $6.1 to $11.8 ha⁻¹ for wheat straw. Residue harvest or addition did not harm short-term biomass yield in Virginia's grain-based cropping systems.