1. The effects of three different qualities of char on soil properties Rachel Unger* rcunger@iastate.edu and Randy Killorn rkillorn@iastate.edu Agronomy Department-Iowa State University Objective This study was done in order to measure the effects of char application on different soil chemical properties. Materials and Methods Collected and dried a Nicollet soil (Fine-loamy, mixed, superactive, mesic Aquic Hapludoll) and a Storden subsoil (Fine-loamy, mixed, superactive, mesic Eutrudept), typical Iowa soils Mixed 100g dried soil with 0.8g of one of three qualities of char which were created by having 0, 10, 25% air present in the reactor while the char was being formed Mixed a urea solution with the soil and char at rates equivalent to 0, 56, 112, 224 kg N ha -1 Treatments were arranged in a complete randomized block study with three replications Incubated at room temperature Used destructive sampling immediately, 1, 2, 4, 6, and 8 weeks Tested for total nitrogen (N) and total organic carbon (C) (S.M. Combs and M.V. Nathan, 1998), phosphorus (P) and potassium (K) (K. Frank, D. Beegle and J. Denning, 1998), and pH (M.E. Watson and J.R. Brown, 1998) Soil tests were run by the Iowa State University Soil Testing Laboratory Results The percent of total N increased when compared over the different chars (Fig. 1) while the percent of total C decreased (Fig. 2). The Nicollet soil pH levels out at around week 6 (Fig. 3), which is similar in the Storden subsoil soil (Fig. 4). Char 3 produced a higher soil pH than the other chars at all sampling times. Soil P decreased until sometime between week 2 and 4 and then an increase to the end of the study (Fig.5 ). The same trend was observed with soil K (Fig. 6). The pH at the 0 kg N ha-1 in the Nicollet soil remained constant, while the pH where N was added decreased (Fig. 7). In the Storden subsoil soil, the pH was decreased in all treatments (Fig. 8). The initial results for each soil property tested by soil can be seen in Table 1. Preliminary Conclusions These data suggest that the char contained bio-available C that decomposed over time releasing P and K, which explains the increase in extractable P and K. The decrease it total C brings into question using char to increase the carbon sinks in the soil. Introduction Using charred organic material is an idea that has been around for hundreds of years. Many areas along the Amazon River Basin have been discovered to have extremely fertile areas believed to have been created through indigenous peoples burning organic materials. It has been shown that char transforms labile carbon pools into stable soil organic matter (Glasser et al. 2001). Char has also been shown to increase the cation exchange capacity (Lehmann et al. 2003) and neutralize pH (Fowles 2007). Using char as a fertilizer has also shown the potential for decreasing the amount of nitrogen fertilizer that needs to be added to the field, but also increasing the carbon sink in the soil (Lehmann et al. 2006). Char has the potential to play a large part in the future of fertilizers. Discussion We have no good explanation at this time for the increase in total N and it needs to be examined further. The decrease in total C could be explained by the presence of biologically active C in the chars, which was utilized by soil micro-organisms as an energy source. The increase in soil P could be attributed to microbial decomposition of the char. One possible explanation for the change in K over time is that K is being physically sequestered and as the char is broken down, K is released. Works Cited Combs, S.M. and M.V. Nathan. 1998. Recommended Chemical Soil Test Procedures for the North Central Region. Revised January 1998. North Central Regional Research Publication No. 221. Fowles M. 2007. Black carbon sequestration as an alternative to bioenergy. Biomass and Bioenergy, doi:10.1016/j.jiombioe.2007.01.012. Frank, K., D. Beegle and J. Denning. 1998. Recommended Chemical Soil Test Procedures for the North Central Region. Revised January 1998. North Central Regional Research Publication No. 221. Glasser, B, Guggenberger G, Haumaier L, Zech W. 2001. Persistence of soil organic matter in archaeological soils (Terra Preta) of the Brazilian Amazon region. In: Rees RM, et al. (eds) Sustainable management of soil organic matter. CABI Publishing, Wallingford, pp 190-19. Lehmann J, da Silva JP Jr, Steiner C, Nehls T, Zech W, Glasser B. 2003. Nutrient availability and leaching in an archaeological Antrhrosol and a Ferrasol of the Central Amazon Basin: fertilizer, manure and charcoal amendments. Plant Soil 249: 343-357. Lehmann, J Gaunt J, Rondon M. 2006. Bio-char sequestration in terrestrial ecosystems-a review. Mitigation and Adaptation Strategies for Global Change 11:403-427, doi 10:1007/s11027-005-9006-5. Watson, M.E. and J.R. Brown.1998. Recommended Chemical Soil Test Procedures for the North Central Region. Revised January 1998. North Central Regional Research Publication No. 221. Figure 1. Change in percent of total N in three different qualities of char over time. Figure 2. Change in percent of total C in three different qualities of char over time. Figure 3. Change in pH of a Nicollet soil in three different qualities of char over time. Figure 4. Change in pH of a Storden subsoil soil in three different qualities of char over time. Figure 5. Mehlich-3 extractable P compared by four different nitrogen fertilizer rates. Figure 6. Mehlich-3 extractable K compared by four different nitrogen fertilizer rates. Figure 7. Change in pH of a Nicollet soil compared across four different nitrogen fertilizer rates. Figure 8. Change in pH of a Storden subsoil soil compared across four different nitrogen fertilizer rates. Table 1. Initial soil properties by soil. SoilpHPKTotal NTotal C Nicollet6.476439.417243.92.19202.1381 Storden8.5O4222.361224.5.07382.0765 p-value<.01 0.1101