PhD THESIS TITLE :
Modeling phosphorus cycling in agroecosystems to optimize agronomical and environmental management
Duration: 3 years
Main workplace : Villenave d’Ornon (south-west of France, close to Bordeaux)
Skill area: ecology, soil and environmental sciences, agronomy, biogeochemistry
Supervised doctoral Thesis: The doctoral degree will be conducted at the Bordeaux 1 University
The PhD work will be done at the INRA research unit called UMR1220 TCEM (Transfert sol-plante et cycle
des éléments minéraux) (http://www7.bordeaux-aquitaine.inra.fr/tcem/).
Subject
The current challenge of managing phosphorus cycling in agroecosystems is to elaborate a processes-based
modeling approach to describe its functioning over successive years of cultivation. The PhD work will be to
complete and improve a model that describes the relationships between changes in plant-available soil P
due to P inputs such as fertilizer and manure application, atmospheric deposits and P in seeds and P
outputs such as P uptake by plants, the fraction export in harvests, P leaches, in run-off… and other
agricultural practices.
The doctoral position will include three steps. Firstly, a conceptual model will be elaborated representing
the functioning of P cycling at the field scale. This model will integrate the quantitative contribution of the
inorganic, organic and microbial components of soil P and their respective ability to supply the plantavailable soil P via biological, physical and chemical processes. Also, the root growth and development will
be accounted for. Secondly, the conceptual model will be tested in long term field experiments dedicated
to P fertilization of crops. Especially, long-term field experiments located in France will be fully analyzed
and interpreted. The objectives of this experiment were to assess the long term effects of tillage practices
(no-till and mouldboard plough) and P fertilizer rates applied to crops on grain yield and soil P status.
Thirdly, the sensitivity of the model will be analyzed with regard to data inaccuracy and scientific
assumptions. The proposed model will be used to evaluate scenarios of P fertilization strategies combined
with soil tillage practices and pedoclimatic conditions and their impact on crop production and
environmental P losses. This interdisciplinary research will use a range of modern techniques and methods
from soil science and agronomy with field and laboratory works and modeling approach.
Qualifications
A Master degree is required. We seek an applicant with background in ecology, soil science, environmental
chemistry, agronomy with excellent qualifications. Demonstrated proficiency in written and oral
communication in English.
Contacts:
Dr A Mollier ([email protected]) and Dr C Morel ([email protected])
71 av E Bourlaux CS20032- F33882 Villenave d'Ornon cedex - France
www7.bordeaux.inra.fr/tcem