Agronomy Research Expertise in Montpellier and Languedoc-Roussillon (South of France)

Agronomy : crops and cropping systemse

Keywords :

Environmental impact of composting

2. Minimizing the impact of cropping on biogeochemical cycles

2. Minimizing the impact of cropping on biogeochemical cycles

Turning compost windrows on the Plaine des Cafres, Réunion (photo: J. Lepetit, 2005) Composting is an interesting technique for better spatiotemporal management of organic matter derived from livestock farming: reduction in mass and volume, enhanced soil fertility, and gradual plant nutrition. However, gas release accounts for some loss during organic matter transformation, sometimes representing as much as 50% of the composted organic matter. This can be detrimental to the environment—acidification and eutrophication for ammonia, greenhouse effect for nitrous oxide and methane. It is therefore of interest to focus on gas emission during composting to assess the environmental impact. Mesocosm measurements were carried out in different composting conditions (15 lots of 1.3 m3) with respect to the main factors controlling the physicochemical processes involved in biomass transformation: biodegradable carbon, available nitrogen, oxygen input, and moisture. The kinetics of instantaneous and cumulated NH3, CO2 and H2O emissions were mathematically adjusted. Multiple linear regression models were than calculated to predict the parameters of these curves with biotransformation control factors as explanatory variables. These statistical models can be used to assess the effects of these factors on gas losses in many composting conditions. Factors influencing N2O and CH4 emissions were also studied. The collected data and findings of this statistical model are now being used to build a dynamic simulation model for carbon and nitrogen transformation during composting. This modelling, which is the focus of PhD thesis research under way in collaboration with an industrial partner (CIFRE convention), should help to predict compost characteristics (nitrogen availability, organic matter quantity and stability) and to assess the transformation process with respect to pollution risks associated with gas emissions.

Contact(s) :
Jean-Marie Paillat,
Paul Robin,
Mélynda Hassouna,

Publication date : 30/05/2010



Updated on 23/03/12


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