Valorization of Organic Wastes Through Agricultural Fertilization: Coupling Models to Assess the Effects of Spreader Performances on Nitrogenous Emissions and Related Environmental Impacts

Organic waste land application generates nitrogenous emissions that have impacts on acidification, eutrophication and global warming. To assess these impacts with Life Cycle Assessment, emission factors are commonly used without taking into account neither the type and performance of land application techniques nor the type of organic waste applied. This paper proposes a methodological framework to assess the nitrogenous emissions by coupling technological performances of spreader and biophysical models, focusing on sewage sludge spreading in different weather and soil conditions. The first step consists of creating several spreading scenarios by combining a cropping system and a spreader/ sewage sludge'' couple. The second step consists of testing the technological spreader performances regarding spatial distribution, application rate and soil compaction with a spreading simulator and the COMPSOIL model. Nitrogenous emissions are then simulated with STICS and DEAC models for different application rates and soil bulk densities. Finally, the simulated nitrogen losses from the models are linked with the real amounts of sewage sludge applied and the compacted soil due to spreader performances. Our approach shows that ammonia emissions during sewage sludge spreading can be directly linked to the spreader performances whereas nitrate leaching depends more on the soil and on the weather conditions. Nitrous oxide emissions mostly depend on the spreader weight and to the soil and the weather conditions. This method paves the way to new approaches: integrating technological performances of machines into biophysical and agricultural models in order to assess environmental impacts of agricultural practices.