Short-Term Effects of Poultry Litter or Woodchip Biochar Amendment in a Temperate Zone Agronomic System

Biochar, a charcoal product produced by the anaerobic thermal decomposition of biomass, can provide agronomic benefits when soil applied. However, research is lacking in temperate region soils investigating specific biochar products and their effects on agronomically important crops. A greenhouse study utilizing poultry litter biochar and a field study utilizing pine woodchip biochar were conducted to observe the effects of biochar application to Northwest Arkansas soils on corn growth and nutrient availability. A third experiment investigated poultry litter and pine woodchip biochar influences on soil water retention. In all three experiments, biochar was applied at three rates (0, 5, and 10 Mg per ha). In the greenhouse and field experiments, biochar treatments were applied in combination with three rates of fertilizer based on soil analyses and recommended rates for yield goals [nitrogen (N) for the field, N and phosphorus (P) for the greenhouse]. Greenhouse results indicated that nutrient-rich poultry litter biochar, particularly at the 10 Mg per ha rate, increased corn height and aboveground biomass and root biomass and morphological features, but not percent mycorrhizal infection of roots. The positive effects on improved crop growth were potentially due to direct biochar nutrient addition and greater acquisition of soil and fertilizer phosphorus through the expansion of the root system. Corn yields increased with the application of woodchip biochar in combination with N fertilizer in the field, but corn yields (in the absence of fertilizer) and soil N decreased with biochar. During a laboratory based, soil-rewetting experiment, soil with poultry litter biochar tended to retain more water at very low water potentials. Poultry litter and pine woodchip biochars may both have beneficial impacts on corn production in temperate soil, but the biochar properties and impacts on nutrient availability and soil-water relationships differ. Additional study into potential mechanisms is needed