Long-term Effects of Aboveground Biomass Removal by Burning on Potential Nutrient Recycling

Abstract

Removing aboveground biomass for dedicated bioenergy production has received much attention recently. However, potential long-term impacts of annual aboveground biomass removal on soil and environmental quality have received much less attention and are generally not well documented. A 7-year study was conducted to estimate long-term differences in potential annual recycling of plant-derived nutrients back to the soil, relative to that removed from the system in wheat grain removal, as affected by burning a high and low level of wheat (Triticum aestivum L.) residue achieved with differential N fertilization. Elemental mass balances were performed to estimate the net input or loss of a suite of plant-derived nutrients based on nutrients removed in wheat grain and returned to the soil surface in the aboveground residue after harvest. Results demonstrated that annual removal of aboveground residue by burning has a substantial negative impact on the potential organic C and a smaller, though still negative, impact on P available for recycling back to the soil. It is imperative that new cultural practices that have the potential to negatively affect soil nutrient pools, such as the annual removal of aboveground biomass as a bioenergy feedstock, be carefully considered before they are recommended for wide spread adoption.