Sugarcane straw, soil temperature and nitrification inhibitor impact N2O emissions from N fertilizer

Authors: SOARES, JOHNNY - Universidade De Campinas (UNICAMP); OLIVEIRA, BRUNA - Agronomical Institute Of Campinas (IAC); LOURENCO, KESIA - Agronomical Institute Of Campinas (IAC); MARTINS, ACACIO - Agronomical Institute Of Campinas (IAC); Del Grosso, Stephen - Steve; DO CARMO, JANAINA - Universidade Federal De Sao Carlos; CANTARELLA, HEITOR - Agronomical Institute Of Campinas (IAC); VARGAS, VITOR - Slc Agricola

Submitted to: BioEnergy Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/4/2019
Publication Date: 7/12/2019
Citation: Vargas, V.P., Soares, J.R., Oliveira, B.G., Lourenço, K.S., Martins, A.A., Del Grosso, S.J., do Carmo, J.B., Cantarella, H. 2019. Sugarcane straw, soil temperature and nitrification inhibitor impact N2O emissions from N fertilizer. BioEnergy Research. 12:801-812. https://doi.org//10.1007/s12155-019-10015-8.
DOI: https://doi.org/10.1007/s12155-019-10015-8

Interpretive Summary: Sugarcane straw is a source of carbon (C) and nitrogen (N) which affects soil temperature and moisture, and therefore soil nitrous oxide (N2O) emissions from fertilized fields. The use of nitrification inhibitor (NI) with N fertilizers is an option to reduce the N2O production, however, sugarcane straw may interfere in the NI efficiency to reduce these losses. We conducted two laboratory studies over nearly 100 days to evaluate: i) the implications of sugarcane straw removal and N fertilization under different temperatures on N2O emissions; and ii) the efficiency of NI to reduce N2O emissions as affected by straw rates. In the first experiment the treatments were: N (0 and 100 kg ha-1), straw (0 and 8 Mg ha-1) and soil temperature (20 and 30ºC); in experiment 2 we included another straw rate (16 Mg ha-1) and NI dicyandiamide - DCD (10 kg ha-1). Straw increased N2O emissions from N fertilizer by 37 and 3-fold in the experiment 1 and 2, respectively. The N2O emission was 62% higher at 20ºC than at 30ºC, whereas the opposite was observed with CO2 emission. There was a synergistic effect of straw, which increased dissolved organic C by more than 50% in the top soil layer and was positively correlated with N2O emission. NI strongly reduced N2O emissions (>69%) regardless of straw rate, with no effect on soil respiration. Such additive is an important strategy to mitigate N2O emissions associated with N fertilization in sugarcane fields where harvest residues are preserved.

Technical Abstract: Sugarcane straw is a source of carbon (C) and nitrogen (N) which affects soil temperature and moisture, and therefore soil nitrous oxide (N2O) emissions from fertilized fields. The use of nitrification inhibitor (NI) with N fertilizers is an option to reduce the N2O production, however, sugarcane straw may interfere in the NI efficiency to reduce these losses. We conducted two laboratory studies over nearly 100 days to evaluate: i) the implications of sugarcane straw removal and N fertilization under different temperatures on N2O emissions; and ii) the efficiency of NI to reduce N2O emissions as affected by straw rates. In the first experiment the treatments were: N (0 and 100 kg ha-1), straw (0 and 8 Mg ha-1) and soil temperature (20 and 30ºC); in experiment 2 we included another straw rate (16 Mg ha-1) and NI dicyandiamide - DCD (10 kg ha-1). Straw increased N2O emissions from N fertilizer by 37 and 3-fold in the experiment 1 and 2, respectively. The N2O emission was 62% higher at 20ºC than at 30ºC, whereas the opposite was observed with CO2 emission. There was a synergistic effect of straw, which increased dissolved organic C by more than 50% in the top soil layer and was positively correlated with N2O emission. NI strongly reduced N2O emissions (>69%) regardless of straw rate, with no effect on soil respiration. Such additive is an important strategy to mitigate N2O emissions associated with N fertilization in sugarcane fields where harvest residues are preserved.