Biochar and manure effluent effects on soil biochemical properties under corn production

Biochar (BC), an aromatic carbon (C) rich compound has been used to sequester C in terrestrial ecosystems. Biochar has also been shown to improve soil fertility and crop productivity when applied to soil. Biochemical properties of soil are sensitive parameters that indicate the change in soil processes that result from soil management practices. Major knowledge gaps exist on the long term effects of biochar addition in cropped field soils. Therefore, a field experiment (3 yrs) was conducted on a Warden silt loam soil to investigate the changes in soil biochemical properties following three years of corn (Zea mays L.) production with applications of biochar (BC), fertilizer (NPK) or dairy manure (DE). The NPK or DE treatments were applied annually, while BC was applied only the first year. Organic carbon (TOC), total organic nitrogen (TON), TOC to TON ratio (CNR), soil microbial biomass carbon (MBC), Metabolic quotient (MQ), potential mineralizable nitrogen (PMN), fluorescein diacetate hydrolysis activity (FDA), acid phophatase activity (ACP), alkaline phosphatase activity (ALP), β-glucosidase activity, urease activity (URA), and soil pH were evaluated at 0-15 and 15-30 cm depths after the 3rd year of corn production. A soil quality index equation was also developed with linear scoring functions. NPK or DE with BC application increased soil pH, TOC, MBC, FDA, CN ratio, ALP and URA while decreased MQ and ACP activity. Biochar had little effect on N dynamics in the soil. Application of biochar to both NPK and DE treatments improved the soil quality index as compared to that without biochar.