Submitted to: Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 18, 2009
Publication Date: January 28, 2010
Repository URL: http://hdl.handle.net/10113/38916
Citation: Busscher, W.J., Novak, J.M., Evans, D.E., Watts, D.W., Niandou, M., Ahmedna, M. 2010. Influence of pecan biochar on physical properties of a Norfolk loamy sand. Soil Science. 175(1):10-14. Interpretive Summary: We added switchgrass and biochar to southeastern Coastal Plain sandy soils in an attempt to improve their poor physical characteristics and low carbon contents. Switchgrass decreased the high soil strength which would permit easier root penetration; it also improved the ability of the soil to hold water for plant growth. The only problem is that these results will be short lived because switchgrass deteriorates quickly. Biochar was produced from ground pecan shells at a relatively high temperature (~1300°F). The biochar was made up of 88% carbon, 69% of which was in a stable chemical structure. Adding it to the soil did not improve water holding capacities but it decreased the high penetration resistance and increased soil carbon. These improvements are expected to be long lasting because of the nature of biochar. These are encouraging results for soils like these that characteristically have high penetration resistances and low carbon contents.
Technical Abstract: Because the southeastern USA Coastal Plain has high temperatures and abundant rainfall, its sandy soils have poor physical characteristics and low carbon contents. To increase soil carbon (C), we added switchgrass (Panicum virgatum) and non-activated recalcitrant pecan biochar. Biochar was developed by pyrolyzing ground pecan shells at 700°C. Biochar had 88% C, 0.4% N (C:N ration 220:1); 58% of its C resided in polymerized aromatic ring structures. Biochar treatments were 0, 5, 10 and 20 g/kg of the soil which was the Ap horizon of a Norfolk loamy sand, a thermic Typic Kandiudult in the USDA classification or an Acrisol in the FAO classification. Switchgrass was ground to a fine powder and added to the biochar treatments at rates of 0 and 10 g/kg. Treatments were incubated in 750 g columns for 70 days at 10% (w/ w) water content. Biochar decreased soil penetration resistance; adding switchgrass generally decreased it more. Biochar and switchgrass affected aggregation, infiltration, and water holding capacity; but results were mixed. Biochar and switchgrass increased soil C; the biochar C was expected to be more recalcitrant than the switchgrass. The non-activated Biochar (and switchgrass) improved some soil physical characteristics; it is possible that activating the charcoal will improve its affect on more characteristics.