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Biochars are the byproduct of anaerobic combustion (pyrolysis) of organic materials. Three biochars (switchgrass, cornstover, and Ponderosa pine woodchip) were created by burning the materials under anaerobic conditions for four hours at maximum temperatures of 850 o C (fast pyrolysis). Biochar samples were sorted by size (< 2 mm, 2-4 mm, and > 4 mm) and electrical conductivity (EC) and pH characteristics were determined in 1:5 (w/v) water and 0.01M CaCl2 . Each biochar type and size was added at 1 and 10% (w/w), to two South Dakota soils, Barnes (loamy) or Maddock (loamy fine sand). Atrazine sorption and changes in soil pH and EC were measured in slurry experiments (1:2 w/v). Biochar pH values were higher than soil pH values; however, the addition of biochar had minimal influence on soil pH. Biochar size affected soil EC values; the smallest sized chars at the 10% addition increased the soil EC. Atrazine sorption from solution increased from about 35% in soil only to almost 99% with each biochar treatment. Targeted biochar addition to soil may be warranted. If atrazine carryover is suspected, addition of biochar may reduce unwanted affects; however, higher sorption may require higher application rates to provide weed control similar to that of nonamended soil.

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Proceedings of the South Dakota Academy of Science



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