An improved carbon fixation management strategy into the crop–soil ecosystem by using biomass ash as the medium

Abstract

Returning the carbonated biomass ash into the soil can enhance the carbon fixation capacity of crop–soil ecosystem, contributing to the achievement of ‘4 per mille Soils for Food Security and Climate’ goal launched at COP21. The CO 2 sequestration of crop–soil ecosystem induced by biomass ash, however, highly depended on the soil pH and crops growth, which have not​ been elucidated. Here, we explored the effects of different management strategies (watering, chemical fertilizer, and CO 2 -rich biogas slurry on the CO 2 fixation performance of tomato ecosystem (Tom-E) containing one tomato plant, biomass ash, and soil, and evaluated the impact of tomato cultivation concerning carbon fixation. Results showed that when burying biomass ash into the soil, biomass ash did not cause physiological stress on tomato growth, and even improved the tomato qualities. Furthermore, through sequestrating CO 2 from biomass ash, CO 2 fixation capacity of the tomato ecosystem reached about 8.8 ± 1.10, 13.7 ± 0.74, and 20.7 ± 0.53 mmol-CO 2 /Tom-E for watering, chemical fertilizer, and CO 2 -rich biogas slurry management strategies, respectively. However, due to the influence of fertilization management strategy, about 57.4% ± 0.09 and 27.3% ± 0.09 of CO 2 sequestrated in the biomass ash returned to the atmosphere ( i.e , CO 2 loss) for only watering treatment and conventional fertilization (chemical fertilizer) treatment, respectively. Comparatively, as a pH buffering fertilizer, CO 2 -rich biogas slurry application improved the bicarbonate assimilation environment of tomato, which contributed to reducing the CO 2 loss to only 12.5% ± 0.01. Clearly, adopting the carbonated biomass ash and CO 2 -rich biogas slurry as fertilizer provides a suitable and potential strategy for the enhancement of soil carbon sink. • Recycling the biomass ash into soil enhanced the carbon sink of tomato ecosystem. • CO 2 -rich biogas slurry application improved the carbon sink of tomato ecosystem. • DIC assimilation rate of tomato increased by recycling the biomass ash. • Different fertilization management strategies caused different CO 2 sequestration.