TY - JOUR
T1 - Differences in N 2 O fluxes and denitrification gene abundance in the wet and dry seasons through soil and plant residue characteristics of tropical tree crops
AU - Nishisaka, Caroline Sayuri
AU - Youngerman, Connor
AU - Meredith, Laura K.
AU - do Carmo, Janaina Braga
AU - Navarrete, Acacio Aparecido
N1 - Funding Information:
We wish to thank Leonardo Machado Pitombo, Isadora Leme, and Rafael Da Róz from the Federal University of São Carlos for their technical support in lab analysis and map preparation. We also wish to thank José Luiz Moreira César and Pedro Conde Filho for sharing the private area for field experiment. This study was supported by a grant from Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP 2016/15289-4 and 2017/17441-0). Greenhouse gases analyses and denitrifiers abundance determination were viable due to GC and qPCR equipment's acquisition supported by FAPESP 2012/50694-6 and 2016/16687-3 granted to improve the laboratory infrastructure.
Publisher Copyright:
© 2019 Nishisaka, Youngerman, Meredith, do Carmo and Navarrete.
PY - 2019
Y1 - 2019
N2 - The conversion of forest to agricultural soils is a widespread activity in tropical systems, and its link to nitrous oxide (N 2 O) fluxes and nitrogen cycling gene abundance is relevant to understand environmental drivers that may interact with climate change. A current challenge to estimating N 2 O emissions from land use conversion is an incomplete understanding of crop-specific impacts on denitrifier communities and the N 2 O fluxes driven by differences in the above- and below-ground inputs with crop type. To address this knowledge gap in tree crops, we evaluated N 2 O fluxes and denitrification gene abundance and their relationships with soil and plant residue characteristics in citrus and eucalyptus plantations in the field and in soil incubations. We found that the accumulated N 2 O fluxes from soil were lower for the two agricultural field sites than those for their adjacent forest sites in dry and wet seasons. The N 2 O fluxes were higher in the wet season, and this seasonal difference persisted even when the soils collected from both seasons were incubated under the same moisture and temperature conditions in the lab for 30 days. Increased N 2 O fluxes in the wet season were accompanied by an increase in soil nirK and nosZ gene abundance, the dissolved organic carbon (DOC) concentration, and the total soil carbon (C) and nitrogen (N) content. In turn, the abundance of denitrifiers, as indicated by nirK, nirS, and nosZ gene copy numbers, showed a low but significant positive correlation with soil bulk density. Our results suggest that soil moisture, leaf litter, and crop residues influence the seasonal differences in both N 2 O fluxes and abundance of denitrifiers in citrus- and eucalyptus-cultivated soils, likely through effects on soil physicochemical characteristics. These findings highlight the overwhelming role of environmental drivers that can make investigating microbial drivers difficult in the field and open the possibility for a better understanding of N cycling processes in tropical soils based on paired field- and incubation-based experimentation.
AB - The conversion of forest to agricultural soils is a widespread activity in tropical systems, and its link to nitrous oxide (N 2 O) fluxes and nitrogen cycling gene abundance is relevant to understand environmental drivers that may interact with climate change. A current challenge to estimating N 2 O emissions from land use conversion is an incomplete understanding of crop-specific impacts on denitrifier communities and the N 2 O fluxes driven by differences in the above- and below-ground inputs with crop type. To address this knowledge gap in tree crops, we evaluated N 2 O fluxes and denitrification gene abundance and their relationships with soil and plant residue characteristics in citrus and eucalyptus plantations in the field and in soil incubations. We found that the accumulated N 2 O fluxes from soil were lower for the two agricultural field sites than those for their adjacent forest sites in dry and wet seasons. The N 2 O fluxes were higher in the wet season, and this seasonal difference persisted even when the soils collected from both seasons were incubated under the same moisture and temperature conditions in the lab for 30 days. Increased N 2 O fluxes in the wet season were accompanied by an increase in soil nirK and nosZ gene abundance, the dissolved organic carbon (DOC) concentration, and the total soil carbon (C) and nitrogen (N) content. In turn, the abundance of denitrifiers, as indicated by nirK, nirS, and nosZ gene copy numbers, showed a low but significant positive correlation with soil bulk density. Our results suggest that soil moisture, leaf litter, and crop residues influence the seasonal differences in both N 2 O fluxes and abundance of denitrifiers in citrus- and eucalyptus-cultivated soils, likely through effects on soil physicochemical characteristics. These findings highlight the overwhelming role of environmental drivers that can make investigating microbial drivers difficult in the field and open the possibility for a better understanding of N cycling processes in tropical soils based on paired field- and incubation-based experimentation.
KW - Citrus
KW - Denitrifiers
KW - Eucalyptus
KW - Nitrous oxide
KW - Tropical soil
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U2 - 10.3389/fenvs.2019.00011
DO - 10.3389/fenvs.2019.00011
M3 - Article
AN - SCOPUS:85064393742
SN - 2296-665X
VL - 7
JO - Frontiers in Environmental Science
JF - Frontiers in Environmental Science
IS - FEB
M1 - 11
ER -