Sustainable Bioenergy Feedstock Production Using Long-term (1999-2014) Conservation Reserve Program Land

摘要

Carbon dioxide concentration is increasing in the atmosphere. This has encouraged the world community to change its energy usages from a fossil resource-based that currently dominates to a renewable bio-based in the future. This opened the door for "solutions from the land" which has led to exploration of land used in the Conservation Reserve Program (CRP) with mixed prairie plant genomes. CRP, a massive public-private partnership program was instituted in 1985 and has reached a total enrolment of about ~10 million hectares that has not been harvested during the past 30 years. Much of the CRP land has degraded, resulting in reduced land cover and a net loss of primary productivity. This research is based on the premise that CRP lands can be harvested for to supply biofuel feedstocks or forage for livestock without long term harmful effects on the plant community and soil environment and without compromising wildlife habitats. This may lead to a Win-Win situation where lignocellulosic materials can be harvested from the CRP lands while at the same time protecting wildlife habitat.;In 2009, CRP land located near Piketon, OH was selected for this study. The site was planted in 1999 with nine different warm-season perennials in a prairie mix that had not been harvested for ten years. The site was burned once in 2009 to get rid of weeds and brambles. Treatments imposed on this land in 2009 were designed to test the effect of N fertilization and harvest timing and frequency on the response of CRP land. Five levels of N (0, 10, 20, 40 and 80 kg N ha-1) and three management strategies (A: Harvest in March or April; B: 1st harvest in May, and 2nd harvest in March or April; and C: Multiple harvests during May through October) with four replications in a factorial randomized complete block design with a strip-block restriction on treatment randomization. Energy yields (GJ ha-1 yr -1) increased from 96.0 in 2009 to 287.0 in 2014 with Management-A, 83.0 in 2009 to 202 in 2014 with Management-B, and 83.0 in 2009 to 194 in 2014 with Management-C. Ecosystem losses of NPK and Ca, Mg, and S (kg Mg -1) were significantly lower with Management-A followed by -B and -C. Soil carbon sequestration (CO2-C Eqvt Mg ha-1) was increased by 70% with Management-A, ~3% with -B and significantly decreased by 21% with -C. Soil quality was found to be affected by time, managements, and all four soil depths. N-applications did not show any effect, except on carbon sequestration which was significantly improved by lower rate of N-applications (i.e. zero and 10 kg N ha-1). Thus, when harvesting aboveground net primary production biomass from CRP land as bioenergy feedstock, the best management strategy was to harvest one time in late winter (Management-A) to could provide a Win-Win situation in which there is a gain in bioenergy feedstock and maintenance of environmental quality compared with other the other harvest strategies evaluated.