Nitrous oxide emissions from cassava fields amended with organic and inorganic fertilizers

Abstract

Cassava production requires nitrogen (N) inputs to drive processes such as protein synthesis. Nevertheless, N not taken up by cassava roots is subjected to microbial transformation resulting in nitrous oxide (N2O) production, a potent greenhouse gas. The temporal dynamics of soil N is partially influenced by the N source (i.e., organic or inorganic fertilizer) and the synchrony between N supply and demand. This study, which was conducted in Colombia on soils with high organic carbon and phosphorus contents, aimed at monitoring N2O emissions from cassava plots fertilized with organic (49.8 kg N ha-1 year-1) or inorganic fertilizers (22.7 kg N ha-1 year-1). Although the organic fertilizer (vermicompost) contained more than double the amount of N, cumulative N2O emissions from organic cassava production (1.28 kg N2O-N ha-1) were lower than those from inorganic fertilizer-based cassava production (1.74 kg N2O-N ha-1) system. This finding indicates that, if crop yields can be maintained, there is potential to reduce cassava production's environmental impact through organic fertilization on highly fertile soils. However, a transition to organic fertilization depends on the availability of sufficient amounts of organic fertilizers at the farm level. The N2O emissions in this study were higher than those predicted using the default IPCC emission factor, which confirmed the relevance of using country or regional specific emissions factors.