Greenhouse gases emissions from tropical grasslands affected by nitrogen fertilizer management

Abstract

Abstract Greenhouse gases (GHGs) emissions from livestock systems are important because of their significant contribution to global warming. Nitrogen fertilization can improve system production; however, it alters soil gas emissions. We evaluated soil nitrous oxide (N 2 O), methane (CH 4 ), and carbon dioxide (CO 2 ) emissions to investigate how they are affected by increasing levels of N fertilizer (urea) in a productive Marandu grass [ Urochloa brizantha (Hochst ex A. Rich) Stapf] pasture subjected to continuous grazing by young Nellore beef cattle ( Bos indicus ). The N 2 O, CH 4, and CO 2 emissions were significantly affected by increasing N fertilizer levels. The seasons also affected GHGs emissions. Nitrogen fertilizer favored CH 4 consumption relative to the control plot without N, with mean emission of 23.7 μg CH 4 −C m −2 h −1 in the fertilized plots compared to 61.6 μg CH 4 −C m −2 h −1 in the control. The N‐fertilized areas presented higher CO 2 emissions compared to the control plot without N. The areas that received N fertilization showed a positive linear association between the water‐filled pore space and N 2 O emission. Soil temperature drove CO 2 emissions. Increasing N fertilization in grazed marandu grass increases N 2 O and CO 2 emissions during the growing season, while reducing CH 4 . The effect of fertilization during the transition season was not apparent, and perhaps other factors could provide a better explanation for the GHG emissions during this period.