Root Biomass and Mycorrhizal Infection of Corn in Loam Soil Amended with Poultry Litter Biochar.

Biochar may increase plant growth and nutrient uptake by stimulating the activity and plant infection of mycorrhizal fungi. A greenhouse experiment was conducted to determine if poultry litter biochar stimulated mycorrhizal infection and plant nutrient uptake when fertilized at lower than recommended N and P rates. Treatments (n=4), including poultry litter biochar (0, 5, and 10 Mg ha^-1) and fertilizer (0, half, and full recommended rates), were established in a randomized complete block. Soils and plants were sampled when the corn reached tasseling stage. Biochar application did not affect mycorrhizal infection (P < 0.05). Root biomass, average root diameter, plant height, and aboveground biomass were affected by fertilizer, with the greatest values in the fully fertilized soil followed by half and no addition. Root biomass, average diameter, and ear leaf P concentration were also affected by biochar with greater values with 10 Mg ha^-1 than with 5 or 0 Mg ha^-1. Plant height and aboveground biomass were significantly larger with biochar addition compared to no addition. Root length, surface area, and volume were all greatest in the fully fertilized soil receiving 10 Mg ha^-1 biochar compared to all other treatments (P < 0.05). Although biochar application did not impact percent mycorrhizal infection, aboveground and belowground corn biomass and ear leaf P did increase as a result of biochar application, either alone or in interaction with fertilizer. Poultry litter biochar may improve agronomic performance of corn grown in midsouthern U.S. soils, but future research should further investigate mechanisms for maximum benefits.