Improvement of Soil Physical Quality by Organic and Inorganic Amendments.

Impacts of Biochar and Other Amendments on Soil Quality Atanu Mukherjee* and Rattan Lal* *: School of Environment and Natural Resources, CMASC, The Ohio State University, Columbus, OH Physical processes of aggregation, water retention and chemical reactions between organic functional groups and mineral phase are among important determinants of soil quality. However, these interactive physical and chemical processes are not well understood. Soil management practices to improve soil quality must identify mechanisms by which mean residence time (MRT) of soil carbon (C) can be improved. Aggregate stability, pore size distribution (PSD), bulk density (BD), surface area (SA), natural binding, complexing or chelating agents are the factors which control MRT of C. Thus, experiments at different scales ((i) laboratory leaching study, and (ii) field plot experiments) are required to evaluate influence of organic (biochar and coal derived HA) and inorganic (aluminium based water treatment residuals (WTR)) amendments on MRT and C sequestration. One kg soil was incubated with amendments (biochar, HA, and WTR) at 1% (w/w) rate of application in 12 transparent soil columns under laboratory condition. Columns were leached weekly with 200 mL water and leachates were collected and saved for C and N determination. In addition, gaseous samples were collected from headspace of each column simultaneously. The MRT of C was estimated from C mineralization rate under laboratory controlled conditions. Similarly, 12 plots (2 m x 2 m) were prepared in Waterman Farm, Columbus, Ohio and amendments were randomly distributed in the plots. Soybean was planted and weekly gaseous samples were collected from installed gas chambers. Critical soil quality factors such as BD, SA, PSD, pH, moisture content were determined and correlated to understand the soil-processes involved.