GCZSC - Postdoc in Emerging Phosphorus Limitations in shifting Cultivation Systems and Implications

Organisation/Company MOHAMMED VI POLYTECHNIC UNIVERSITY Research Field Agricultural sciences Computer science Mathematics Environmental science Geosciences Researcher Profile Recognised Researcher (R2) Established Researcher (R3) Final date to receive applications 19 Nov 2026 - 00:00 (UTC) Country Morocco Type of Contract Permanent Job Status Full-time Is the job funded through the EU Research Framework Programme? Not funded by a EU programme Is the Job related to staff position within a Research Infrastructure?

No

Job Title:

GCZSC – Postdoc in Emerging Phosphorus limitations in shifting cultivation systems and implications for cash crops yields and carbon sequestration

Area of specialization:
Critical Zone is the “heterogeneous, near-surface environment in which complex interactions involving rock, soil, water, air, and living organisms regulate the natural habitat and determine availability of life-sustaining resources”. Its limits range from the top of the canopy down to the bottom of the aquifer. The successful applicant to this position will join the Global Critical Zone Science Chair to develop and conduct a research program to strengthen the understanding of:

Emerging Phosphorus limitations in shifting cultivation systems and implications for cash crops yields and carbon sequestration

This postdoctoral position, jointly hosted by LSCE (France) and UM6P (Morocco) sharing his (her) time between the two countries, investigates emerging phosphorus limitations in shifting cultivation systems of Central Africa. The successful candidate will use advanced land surface modeling calibrated to observations from field trails and satellites to assess implications for crop yields and carbon sequestration under accelerating land-use pressures.

Background

Shifting cultivation, also called slash and burn agriculture is a widespread traditional cultivation practice in wet tropical forests of central Africa. Small-holder farmers will burn and clear forests in dry seasons, followed by cultivation of diverse cash crops for periods ranging between 15 and 35 years, after which secondary forest regrow. During forest regeneration ecosystems accumulate carbon and restore nitrogen and phosphorus availability via re-distribution within different forms of nutrients present in soils, reduced losses, and inputs from biological N fixation, rock weathering, atmospheric deposition).

A growing concern is that shifting cultivation is expanding into the Congo basin driven by an increasing population & food demand. This leads to an expansion of small clearings and to an acceleration of rotation between forests and crops, with shortening forest regrowth intervals between crop cultivations. The implications are poorly known but accelerated rotations & expansion of shifting cultivation in space are expected to reduce carbon stocks in biomass and soils, and enhance nitrogen and phosphorus losses in Central Africa.

When soil fertility declines are not treated more land will be required to maintain food production. Adequate and timely input of the right type of fertilizers and target crop management (e.g. residues) can help to alleviate, or even avoid, this limitation, with direct benefits for yield stability and food security, and indirect benefits for reducing deforestation and enhancing ecosystem level time averaged carbon storage in soils and forest biomass of shifting cultivation systems.

The proposed postdoctoral subject is to use the land surface model ORCHIDEE CNP model which resolves major processes governing the ecosystem balance of carbon, nitrogen and phosphorus and their internal cycling between minerals, soils (incl. microbes) and plants. We will use the model to simulate the evolution of biogeochemical cycles under shifting cultivation with varying time for forest regeneration. A prior model calibration to crop yield and yield response from fertilizers trials (in collaboration with OCP Nutricrops) and satellite observed forest biomass recovery will enhance the model accuracy.

The model will be integrated for different environmental conditions (e.g. soil background phosphorus availability), and tested for different achievable yields and assumed forest rotations times between two successive cultivation cycles. This will lead to a first publication analyzing carbon and nutrient budgets at system level, that is not only crops but crop and forest shifting cultivations systems. In a second step, the model will be integrated with phosphorus fertilizer practices in subsistence cropping systems, to quantify the benefits for yields and the impacts on carbon storage from a system perspective, including cropland soils and secondary forest biomass.

Simple empirical calculations of how carbon credits potentially generated by improved shifting cultivation management practices could bring revenues to farmers and leverage their access to more efficient fertilizers and cultivation practices, in order to reduce agricultural land…