Effect of cover crops on greenhouse gas emissions in an irrigated field under integrated soil fertility management
Agronomical and environmental benefits are associated with replacing winter fallow by cover crops (CCs). Yet, the effect of this practice on nitrous oxide (N<sub>2</sub>O) emissions remains poorly understood. In this context, a field experiment was carried out under Mediterranean conditi...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-09-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/13/5245/2016/bg-13-5245-2016.pdf |
| Summary: | Agronomical and environmental benefits are associated with replacing winter
fallow by cover crops (CCs). Yet, the effect of this practice on nitrous oxide
(N<sub>2</sub>O) emissions remains poorly understood. In this context, a field
experiment was carried out under Mediterranean conditions to evaluate the
effect of replacing the traditional winter fallow (F) by vetch (<i>Vicia
sativa</i> L.; V) or barley (<i>Hordeum vulgare</i> L.; B) on greenhouse gas
(GHG) emissions during the intercrop and the maize (<i>Zea mays</i> L.)
cropping period. The maize was fertilized following integrated soil fertility
management (ISFM) criteria. Maize nitrogen (N) uptake, soil mineral N
concentrations, soil temperature and moisture, dissolved organic carbon (DOC)
and GHG fluxes were measured during the experiment. Our management (adjusted
N synthetic rates due to ISFM) and pedo-climatic conditions resulted in low
cumulative N<sub>2</sub>O emissions (0.57 to
0.75 kg N<sub>2</sub>O-N ha<sup>−1</sup> yr<sup>−1</sup>), yield-scaled N<sub>2</sub>O emissions
(3–6 g N<sub>2</sub>O-N kg aboveground N uptake<sup>−1</sup>) and N surplus (31 to
56 kg N ha<sup>−1</sup>) for all treatments. Although CCs increased N<sub>2</sub>O
emissions during the intercrop period compared to F (1.6 and 2.6 times in B
and V, respectively), the ISFM resulted in similar cumulative emissions for
the CCs and F at the end of the maize cropping period. The higher C : N
ratio of the B residue led to a greater proportion of N<sub>2</sub>O losses from
the synthetic fertilizer in these plots when compared to V. No significant
differences were observed in CH<sub>4</sub> and CO<sub>2</sub> fluxes at the end of the
experiment. This study shows that the use of both legume and nonlegume CCs
combined with ISFM could provide, in addition to the advantages reported in
previous studies, an opportunity to maximize agronomic efficiency (lowering
synthetic N requirements for the subsequent cash crop) without increasing
cumulative or yield-scaled N<sub>2</sub>O losses. |
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| ISSN: | 1726-4170 1726-4189 |