Impacts of adding biochar on nitrogen retention and bioavailability in agricultural soil

Publication date: September 2013
Source:Geoderma, Volume 206
Author(s): Hao Zheng , Zhenyu Wang , Xia Deng , Stephen Herbert , Baoshan Xing
Interest in the use of biochar to improve soil productivity has rapidly increased. Nitrogen (N) loss, retention and bioavailability in biochar-amended soils fertilized with NH4 ⁺–N and NO3 ⁻–N were studied using leaching and pot experiments. NO3 ⁻–N leaching from the soils fertilized with NH4 ⁺–N and NO3 ⁻–N was significantly reduced by biochar addition. NH4 ⁺–N leaching from the NO3 ⁻–N fertilized soil was also significantly reduced by biochar, while no significant effect was observed for the NH4 ⁺–N fertilized soil. Also lower NH4 ⁺–N and NO3 ⁻–N were leached from NO3 ⁻–N fertilized soil with maize (Zea mays L.) grown. Mitigation of N leaching loss following biochar addition is mainly attributed to the increase in soil water holding capacity (WHC), NH4 ⁺ adsorption and enhanced N immobilization. Biochar addition stimulated maize growth, both above and below ground. Biochar also increased N utilization efficiency (NUE) of maize but decreased N accumulation efficiency (NAE), indicating that biochar addition may improve N bioavailability in agricultural soils. Therefore, reduction of N leaching, and increase of N retention and bioavailability in agricultural soils can potentially decrease the N fertilizer demand for crop growth.