Efficacy of Designer Biochars in Modifying Water Infiltration Rates Through An E Horizon of a Typic Kandiudult.

Ultisols in the Southeastern Coastal Plain region commonly have well-developed E horizons that reconsolidate after deep tillage.  Reconsolidation of these E horizons transforms them into a hard setting subsoil layer causing both poor water infiltration and meager root penetration into deeper subsoil layers.  It was hypothesized that biochars could be designed to improve water infiltration rates through the consolidated E horizon by decreasing bulk densities and through an increase in porosity.  Designer biochars were created by slow pyrolysis (500°C) of pelleted feedstocks (diameter < 6 mm) of pine chips, poultry litter and their blends (50:50 and 80:20 PC:PL).  A comparison was also made with dust-sized (< 0.42-mm) hardwood biochar produced by fast pyrolysis (500-600°C).  Biochars were mixed into columns of a Norfolk E horizon at 20 g/kg, laboratory incubated, and then were leached monthly with water.  Results show that biochar additions, particularly the pure-wood biochars, improved infiltration rates almost 2 to 3-fold greater than untreated controls.  Blending the pine chip and poultry litter biochars caused intermediate improvements in infiltration rates.  These results indicate that designer biochars as a soil amendment can improve water movement into and through soil horizons that have limited infiltration rates.