Abstract
In a lowland drinking water catchment area, nitrate leaching as well as groundwater recharge (GWR) was investigated in willow and poplar short rotation coppice (SRC) plantations of different ages, soil preparation measures prior to planting and harvesting intervals. Significantly increased nitrate concentrations of 16.6 ± 1.6 mg NO3-N L−1 were measured in winter/spring 2010 on a poplar site, established in 2009 after deep plowing (90 cm) but then, subsequently decreased strongly to below 2 mg NO3-N L−1 in spring 2011. The fallow ground reference plot showed nitrate concentrations consistently below 1 mg L−1 and estimated annual seepage output loss was only 1.36 ± 1.1 kg ha−1 a−1. Leaching loss from a neighboring willow plot from 2005 was 14.3 ± 6.6 kg NO3-N ha−1 during spring 2010 but decreased to 2.0 ± 1.5 kg NO3-N ha−1 during the subsequent drainage period. A second willow plot, not harvested since its establishment in 1994, showed continuously higher nitrate concentrations (10.2 ± 1.7 NO3-N L−1), while a neighboring poplar plot, twice harvested since 1994 showed significantly reduced nitrate concentrations. Water balance simulations, referenced by soil water tension and throughfall measurements, showed that at 655 mm annual rainfall, GWR from the reference plot (300 mm a−1) was reduced by 40 % (to 180 mm a−1) on the 2005 willow stand, mainly due to doubled rainfall interception losses. However, transpiration was limited by low soil water storage capacities, which in turn led to a moderate impact on GWR. We conclude that well-managed SRC on sensitive areas can prevent nitrate leaching, while impacts on GWR may be mitigated by management options.
Highlights
To combat climate change and improve security of energy supply, bioenergy derived from forestry and agriculture plays a key role in the European Union (EU)
According to the binding targets set by the EU Renewable Energy Directive (RED), all Member States should strive to a 20 % share of renewable energy by 2020
It is required that EU member states achieve at least a 10 % share of renewable energy of the total gasoline and diesel consumed in the transport sector by the year 2020 [2]
Summary
To combat climate change and improve security of energy supply, bioenergy derived from forestry and agriculture plays a key role in the European Union (EU). It is required that EU member states achieve at least a 10 % share of renewable energy (biofuel) of the total gasoline and diesel consumed in the transport sector by the year 2020 [2]. An assessment made by the European Environment Agency found that about 85 % of the potential bioenergy supply can be produced by only seven member states (Spain, France, Germany, Italy, UK, Lithuania and Poland; [3]). To achieve these goals, approximately 17.5 million ha of land will have to be dedicated to the production of energy crops by 2020 [4].
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