Influence of Poultry Litter Biochar on Soil Properties and Plant Growth

Abstract

Biochar created from poultry litter is a way to produce a value-added soil amendment that is lighter and less expensive to transport out of manure nutrient excess areas, but effects on soil properties are unknown. Two studies were conducted with a Sandy loam and a Silt loam. First, lettuce seeds were germinated across biochar incorporation rates from 0% to 100% biochar, and second, a greenhouse trial was conducted in which peppers were grown in soils with up to 5% biochar by weight. Elemental analysis was completed on the biochar, and soils were analyzed for bulk density, water-holding capacity, pH, cation exchange capacity, and extractable nutrients. Biochar increased lettuce germination by almost 50% in the Sandy loam at low rates but became toxic at rates greater than 2.5% in both soils probably due to salt toxicity. Water-holding capacity increased linearly with biochar additions. For example, adding 15% biochar nearly doubled the water-holding capacity of the Sandy loam from 15% to 27%. The biochar had a pH of 9.3, and additions increased the pH of both soils. Total phosphorus (P) in the biochar was 43 g kg−1, and although almost none of this was water soluble in the pure biochar, the Mehlich 1 P and Olsen P were greatly increased in biochar amended soils. Biochar consistently increased the cation exchange capacity only at high rates. Biochar made from poultry litter showed several benefits as a soil amendment, but application rates would be limited by soil test P and pH.