Climate change effects on northern Spanish grassland-based dairy livestock systems

Background
Understanding the effects of climate change on agro-ecosystems is fundamental in order to select the optimum management practices to mitigate environmental pressures. There is a need to forecast greenhouse gas emissions (GHG) emissions of grassland systems under climate change scenarios whilst also accounting for SOC sequestration.

The objective of this study is to assess the net GHG emissions over > 405,000 hectares (ha) of moist temperate Northern Spanish grasslands utilised for dairy production, under climate change conditions (i.e., RCP 4.5, and RCP 8.5), compared to a reference baseline scenario. It is hypothesised that net GHG will increase under climate change conditions and that implementing specific manure management practices (namely the anaerobic digestion (AD)) may mitigate the global warming effect.

Methods
We used an integrated modelling framework comprising: (i) geographic information systems (GIS); (ii) a modified RothC version to simulate SOC changes in managed grasslands under moist temperate conditions; and (iii) Tier 2 recent IPCC methods to estimate GHG emissions.

Results
Average net GHG emissions contributed to global warming potential with average emissions of 5.8 and 6.2 Mg CO2-e ha−1 year−1, under RCP 4.5 and RCP 8.5, respectively. Anaerobic digestion allowed net GHG under both climate change scenarios to equal net GHG under the baseline reference scenario.

Conclusion
Under climate change conditions, implementing specific manure management practices, namely AD, will likely reduce the net GHG emissions of the grassland systems associated with dairy production in Northern Spain.