Fertilization strategies to reduce yield-scaled N2O emissions based on the use of biochar and biochar-based fertilizers

Abstract

Abstract Novel fertilization strategies, such as the use of biochar-based fertilizers (BBFs) and the co-application of biochar with mineral fertilizers, have shown promising results for mitigating nitrous oxide (N 2 O) emissions and reducing N losses in agroecosystems. Two greenhouse experiments were performed with radish to evaluate: (1) the mitigation of yield-scaled N 2 O emissions using BBFs, produced at either 400 or 800 °C and enriched with urea, compared to the co-application of raw biochars with urea; and (2) the N 2 O mitigation potential of low rates of raw biochars, equivalent to those used with BBFs fertilization, co-applied with low and high N rates (90 and 180 kg N ha −1 ). BBF produced at 800 °C reduced yield-scaled N 2 O emissions by 32% as compared to the urea treatment, and by 60%, as compared to the combination of raw biochar with urea. This reduction was attributed to the slow rate of N release in BBF. On the contrary, the co-application of low rates of biochar with urea increased yield-scaled N 2 O emissions as compared to the fertilization with urea alone. Low rates of biochar (1.4–3.1 t ha −1 ) reduced yield-scaled N 2 O emissions only with a high rate of N fertilization. High-pyrolysis-temperature biochar, co-applied with synthetic fertilizer, or used to produce BBFs, demonstrated lower yield-scaled N 2 O emissions than biochar produced at a lower pyrolysis temperature. This study showed that BBFs are a promising fertilization strategy as compared to the co-application of biochar with synthetic fertilizers.