Study and modelling of the carbon cycle through plant organs and microorganisms of a legume-cereal agrosystem

The objective of this internship was to collect the data necessary to apply a Model of the transformations of Organic matter by Micro Organisms of the Soil (MOMOS) to one cultural cycle of a legume-cereal agrosystem in the region of Languedoc-Rousillon, France. Three modes of culture were studied: faba bean, durum wheat and the association of faba bean and durum wheat. Experimental data was collected on C and N content of microbial biomass, plant organs and soil. Soil respiration was measured on the field. The previously determined values for MOMOS optimal parameters, relationships linking parameters to quality of inputs, soil texture and climate, were preserved in this study. Within our Mediterranean context, the only changes introduced to MOMOS (which had been calibrated and validated in acidic tropical conditions) were the local correction factors of temperature and moisture, quality of plant materials and edaphic properties. The plant production module was also adapted to suit the experimental set up. Experimental data was then plotted against model predictions for MOMOS-C (carbon). Results showed proximity between measured and predicted values of carbon content in plant organs, soil and microbial biomass. Field respiration measurements which included respiration of active roots were found to be quite higher than predicted microbial heterotrophic respiration. Model predictions indicated higher microbial C content and higher microbial respiration activity in wheat parcels than in faba bean. Microbial biomass and microbial activity responded quickly to changes in environmental conditions such as soil moisture levels and inputs of plant necromass.

Bibliographic Details

Main Author:	MacDonald, Patricia
Format:	thesis biblioteca
Language:	eng
Published:	Université de Savoie
Subjects:	P34 - Biologie du sol, U10 - Informatique, mathématiques et statistiques, F08 - Systèmes et modes de culture,
Online Access:	http://agritrop.cirad.fr/579736/ http://agritrop.cirad.fr/579736/1/ID579736.pdf
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