Effects of manure feedstock biochars on micronutrient and heavy metal accumulations in cotton

When planning amendment of soil with biochar, selection of potential feedstocks - from both soil conditioning and plant fertilizing angles - must be considered. In this study we report the effects of five manure-derived feedstocks (beef, chicken, dairy, turkey, and swine) at two different pyrolysis temperatures (350 and 700) on nutrient and heavy metal concentrations (leaf and stem samples) in cotton (Gossypium hirsutum L.). Biochar was added to a Norfolk loamy sand soil based on 40 mg/kg available phosphate (P2O5). The greatest leaf and stem biomass results derived from soil amended with swine manure pyrolysed at 700 C; which also resulted in the largest measured leaf areas after 60 days of growth. Swine manure feedstock pyrolysed 700 C also resulted in the greatest amounts of P plant accumulation in both leaves and stems. However, swine manure pyrolysed at 700 C resulted in only modest levels of K plant accumulation. Like previous results which indicate that feedstocks play a significant role in affecting both soil physicochemical and soil microbial community properties, these results reinforce the idea that feedstocks have different fertilization properties and must be chosen under certain criteria. These criteria include, but are not limited to, soil series, soil nutrient levels, and plant type to be grown.