2008 Annual Report 1a.Objectives (from AD-416) Evaluate the recycling of soil char and bio oil carbon as a byproduct of pyrolysis and determine the effect of the N enriched char byproduct on soil microbial activity measured through CO2 evolution and plant response. 1b.Approach (from AD-416) Char will be characterized for relevant agronomic properties, and changes in soil chemistry, nutrient levels, C dynamics, and microbial activity documented in soils incubated with various char rates and materials. Greenhouse pot studies will be performed to characterize tillage-induced CO2 loss and plant response. Field studies with buried pots will be used to determine changes in soil chemistry and microbial activity as measured by CO2 evolution. 3.Progress Report This work contributes to a better understanding of carbon cycling in biomass for bioenergy systems with emphasis on the use of biochar co-products as a soil amendment. Soil pH is a general chemical measure of soil properties that indicates whether the soil is acid or basic in its reaction. In this work, three different soils and 12 different char materials were analyzed for pH, total carbon and nitrogen, and impacts on microbial respiration to better understand carbon cycling. We conducted the studies to provide new information on the potential impact of bioenergy (pyrolysis and gasification) co-products on soil properties. The pH results of the soil, char, and soil/char mixes in this study obtained thus far are being collected and summarized. The char materials were digested for elemental analysis of nutrient composition. The remaining char samples are presently being analyzed in the laboratory for microbial respiration. The results show that char added to the soils will generally increase the soil pH and may raise the pH beyond the optimum range for most plant nutrient availability. The results also suggest that the buffer capacity of the soil controlled the increase in pH. In summary, these pH results suggest caution for considering biochar as a soil amendment on basic soils. The need for more research on the impact of biochar on pH and nutrient availability in acid and alkaline soils is evident. This project is associated with Objective 1C of the parent project: Assess greenhouse gas emission and C storage from traditional (e.g. corn, soybean) and biofuel crops (switchgrass).