Location: Northwest Irrigation and Soils Research
Title: Biochar and manure affects calcareous soil and corn silage nutrient concentrations and uptake Authors
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 9, 2011
Publication Date: July 1, 2012
Citation: Lentz, R.D., Ippolito, J.A. 2012. Biochar and manure affects calcareous soil and corn silage nutrient concentrations and uptake. Journal of Environmental Quality. 41(4): 1033-1043 DOI: 10.2134/jeq2011.0126. Interpretive Summary: Increasing additions of anthropogenic greenhouse gases (GHG) to earth’s atmosphere are believed to cause global warming. Burning coal and oil for energy releases GHGs and exacerbates the problem. Converting renewable biomass to energy and returning the stable charcoal byproducts (biochar) of this process to the soil could reduce our dependency on oil and slow or reverse the buildup of GHGs in the atmosphere. However, biochar’s affect on soil chemistry and productivity is not fully understood. This study shows that biochar’s first-year effects on irrigated, calcareous soils are minor. However, in year two biochar reduced the uptake of nitrogen and sulfur by the corn crop and reduced silage yield. This information about the effects of biochar on calcareous soils is important because it provide guidelines for safe and effective use of biochar applications to agricultural soils.
Technical Abstract: When added to soils, carbon-rich biochar derived from the pyrolysis of woody materials can sequester atmospheric carbon dioxide, mitigate climate change, and potentially increase crop productivity. However, research is needed to confirm the suitability and sustainability of biochar application to different soils. We applied four treatments (dry wt.) to an irrigated calcareous soil in Nov. 2008: control; stockpiled dairy manure, 18.8 Mg/ha; hardwood-derived biochar, 22.4 Mg/ha; and manure + biochar using previous rates. Nitrogen fertilizer was applied when needed (based on pre-season soil test N and crop requirements) in all plots and years with N mineralized from added manure included in this determination. Available soil nutrients (NH4-N, NO3-N, Olsen P, diethylenetriaminepentaacetic acid (DTPA)-extractable K, Mg, Na, Cu, Mn, Zn, Fe), total C and N (TC, TN), total organic C (TOC), and pH were determined periodically, and silage corn nutrient concentration, yield, and uptake were measured over two growing seasons. Biochar treatment resulted in a 1.5-fold increase in available soil Mn and 1.4-fold increase in TC and TOC, where manure produced a 1.2- to 1.7-fold increase in soil macro- and micro-nutrients (except Fe), compared to controls. In 2009, biochar increased corn silage B concentration but produced no yield increase; and in 2010, biochar decreased corn silage TN (33%), S (7%) concentrations, and yield (36%) relative to controls. Manure produced a 1.3-fold increase in corn silage Cu, Mn, S, Mg, K, and TN concentrations and yield compared to the control in 2010. The combined biochar-manure effects were not synergistic, except in the case of available soil Mn. In these calcareous soils biochar did not alter pH or availability of P and cations, as is typically observed for acidic soils. If the second year results are indicative of future effects, they suggest that biochar applications lead to reduced N availability in calcareous soils and may need to be accompanied by additional N inputs if yield targets are to be maintained.