Impacts of projected climate change on productivity and nitrogen leaching of crop rotations in arable and pig farming systems in Denmark

Abstract

SUMMARYThe effects of projected changes in climate and atmospheric CO2 concentration on productivity and nitrogen (N) leaching of characteristic arable and pig farming rotations in Denmark were investigated with the FASSET simulation model. The LARS weather generator was used to provide climatic data for the baseline period (1961–90) and in combination with two regional circulation models (RCM) to generate climatic data under the Intergovernmental Panel on Climate Change (IPCC) A1B emission scenario for four different 20-year time slices (denoted by midpoints 2020, 2040, 2060 and 2080) for two locations in Denmark, differing in soil and climate, and representative of the selected production systems. The CO2 effects were modelled using projected CO2 concentrations for the A1B emission scenario. Crop rotations were irrigated (sandy soil) and unirrigated (sandy loam soil), and all included systems with and without catch crops, with field operation dates adapted to baseline and future climate change. Model projections showed an increase in the productivity and N leaching in the future that would be dependent on crop rotation and crop management, highlighting the importance of considering the whole rotation rather than single crops for impact assessments. Potato and sugar beet in arable farming and grain maize in pig farming contributed most to the productivity increase in the future scenarios. The highest productivity was obtained in the arable system on the sandy loam soil, with an increase of 20% on average in 2080 with respect to the baseline. Irrigation and fertilization rates would need to be increased in the future to achieve optimum yields. Growing catch crops reduces N leaching, but current catch crop management might not be sufficient to control the potential increase of leaching and more efficient strategies are required in the future. The uncertainty of climate change scenarios was assessed by using two different climate projections for predicting crop productivity and N leaching in Danish crop rotations, and this showed the consistency of the projected trends when used with the same crop model.

Effect of temperature and precipitation on nitrate leaching from organic cereal cropping systems in Denmark

“…Several studies have addressed the effects of climate change on N leaching of crops like winter wheat and spring barley in Denmark (Olesen et al, 2007a;Patil et al, 2012;Doltra et al, 2014). Conclusions from these studies support the general notion that N leaching from cereal cropping systems may increase substantially in response to projected climate change.…”

“…With increased temperatures, soil organic matter turnover increases and this potentially increases available soil mineral N, thus amplifying the risk of N leaching (Børgesen and Olesen, 2011). Moreover, we believe that changes in air temperature will also involve changes in planting and harvesting times as well as in fertilization rates and strategies (Doltra et al, 2014), which will also affect nitrate leaching. Later planting and earlier harvest of winter cereals may result in a prolonged period of bare soil in autumn, which will increase the risk of N leaching (Patil et al, 2012), particularly in connection with increased autumn and winter precipitation.…”

“…plant species, sowing date) might not be sufficient to avoid the potential future increase in N leaching. The choice of the most convenient strategy would be site and rotationspecific, and should be combined with an efficient schedule and application of fertilizers and manure handling according to the rotation requirements (Doltra et al, 2014). Therefore, further studies must be conducted to identify suitable crop rotation and soil and crop management techniques to prevent increased nitrate leaching under projected climate change.…”

How to manage uncertainty in future Life Cycle Assessment (LCA) scenarios addressing the effect of climate change in crop production

“…Even the projections of the future climate effects included in the last IPCC assessment report rely on modelling studies based predominantly on single-factor treatments. The only study retrieved from literature addressing the effects of climate change on future crop production, namely spring barley production in Denmark under future circumstances (Dijkman, 2013) uses the data provided by Doltra et al (2012), who used the dynamic FASSET crop model (Berntsen et al 2003). This model was calibrated and tested for use in the environmental conditions of Denmark, and simulates crop growth and yield as affected by temperature, solar radiation, water and N availability and [CO 2 ].…”

“…One of the regions which is supposed to benefit from the effect of climate change is Northern Europe . Many studies have been performed to project climate change impacts on crop productivity for cereals, mainly wheat, barley and oat in Scandinavia (Doltra et al, 2012;Olesen, 2008;Rötter et al, 2012;. Recently there has also been a growing interest in the assessment of the potential environmental impacts of grain production in this region, e.g.…”