Field Trials With Poultry Litter Biochar and Its Effect on Forages, Green Peppers, and Soil Properties

Pyrolysis offers a way to convert poultry litter into a carbon-rich soil amendment. This study was conducted to evaluate the effects of biochar made from poultry litter on soil chemical properties and plant production. The rates of 0, 4.5, and 9 Mg ha−1 were used at three field sites, and the rates were applied once a year in the early spring of 2009 and 2010. Biochar was surface applied on a tall fescue pasture (Lolium arundinaceum (Schreb.) Darbysh. (= Festuca arundinacea Schreb. subsp. arundinacea)) in the Shenandoah Valley and tilled in on two green pepper (Capsicum annuum L.) field sites in southwestern Virginia. The biochar had a carbon content of 25 ± 1%, and application increased soil carbon by 0.51% after 2 years of application of 9 Mg ha−1 at the forage site where it was surface applied and by an average of 0.38% at the two green pepper sites where it was tilled in. The biochar had a pH of 9.57 ± 0.01 and increased the pH of the soil where it was applied each year. Changes in soil cation exchange capacity showed no clear trends. Mehlich 1 P was increased by 57 mg kg−1 for each Mg ha−1 of biochar at the forage site and by an average of 39 mg kg−1 for each Mg ha−1 of biochar applied at the green pepper sites. The pH and Mehlich 1 P were increased above agronomic levels by the higher rates at all sites, suggesting these as limiting factors. Soluble salts numerically increased in the first year of application but were reduced at all sites through leaching when sampled in the early spring of 2011. No significant differences were found in yields at any of the three sites, but differences in forage quality were found at the tall fescue site probably because biochar increased the rate at which the forage matured.