Impacts of fertilization on grassland productivity and water quality across the European Alps: insights from a mechanistic model
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Date
2020-08-26Type
- Working Paper
ETH Bibliography
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Abstract
Alpine grasslands sustain local economy providing fodder for livestock. Intensive fertilization is common to enhance their yields, thus creating negative externalities on water quality that are difficult to evaluate without reliable estimates of nutrient fluxes. We apply a 1-D mechanistic ecosystem model, seamlessly integrating land-surface energy balance, soil hydrology, vegetation dynamics, and soil biogeochemistry aiming at assessing the grassland response to fertilization. We simulate the major water, carbon, nutrient, and energy fluxes of nine grassland plots across the broad European Alpine region. We provide an unprecedent interdisciplinary model evaluation confirming its performance against observed variables from different datasets. Subsequently, we apply the model to test the influence of fertilization practices on grassland yields and nitrate (NO3) losses through leaching. Despite the generally low NO3 concentration in groundwater recharge, the variability across sites is remarkable, mostly, but not exclusively, dictated by elevation. In high-Alpine sites short growing seasons lead to less efficient nitrogen (N) uptake for biomass production. This combined with lower evapotranspiration rates results in higher amounts of drainage and NO3 leaching to groundwater. The local soil hydrology has a crucial role in driving the NO3 use efficiency. The commonly applied fixed-threshold limit on fertilizer N input is suboptimal. We suggest that major hydrological and soil property differences across sites should be considered in the delineation of best practices or regulations for management. Using distributed maps informed with key soil and climatic attributes or systematically implementing integrated ecosystem models as shown here can contribute to achieving more sustainable practices. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000454430Publication status
publishedExternal links
Journal / series
Biogeosciences DiscussionsPublisher
CopernicusOrganisational unit
03473 - Burlando, Paolo / Burlando, Paolo
Funding
690268 - Use of a Decision-Analytic Framework to explore the water-energy-food NExus in complex and trans-boundary water resources systems of fast growing developing countries. (SBFI)
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Is previous version of: https://doi.org/10.3929/ethz-b-000477217
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