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 Enhancing soil C sequestration in pasture systems, a key mitigation option for countries targets under the UN-Paris Agreement.
The postdoctoral fellow will be trained at the USP/ESALQ Carbon Center in Brazil, (Sao Paulo State) under the supervision of Professor Carlos Eduardo Pellegrino Cerri in relation to the GCZS Chair (professors Rachid Moussadek, Hudson Carvalho, Daniel Nahon).
Based on the relevance of pasture recovering and integrated cropland- livestock-forestry systems (ICLF) for soil C build-up and climate change mitigation, some of the commitments of Brazilian government in the intended Nationally Determined Contribution (iNDC) are restoration of additional 15 million ha of degraded pastures and enhancing 5 million ha of ICLF by 2030. However, the effects of pasture recovering and ICLF systems in soil C changes and its relevance for Brazil achieve the iNDC commitments remains largely unknown. In this sense, the aim of this proposal is providing a pervasive biome-scale analysis of soil C stock changes in pastures and integrated systems in Brazilian Cerrado. Several areas with contrasting edaphic conditions will be sampled across Cerrado biome using a chronosequence approach. For each land use, C and N stocks and isotope composition will be assessed. Rates of soil C change will be used to estimate the contribution of both strategies (pasture recovery and ICLF systems) to climate change mitigation in Brazil. Besides being critical to Brazil achieve iNDC commitments, such effort would be a useful tool for the evaluation of ABC Program and to encourage decision makers and planners to diffuse sustainable land use strategies and soil management systems in Brazil.
Job description:
The Global Critical Zone Science Chair at the Mohammed VI Polytechnic University (UM6P) invites applications for a two years postdoc fellowship (candidates from Moroccan or African universities). The successful applicant will conduct research in C and N Geochemistry aiming to quantify the soil C and N stocks, and isotopic composition in livestock areas in brazilian soils (Cerrado) which are very close to those of the African Sudano-Sahelian zone which is one of the points of interest for the development of research and its application to the agronomic system of Africa (designing and development of sustainable agricultural systems). The successful applicant will provide a great understanding in global warming discussions, increasing soil C and reduce deforestation. In this sense , Brazil is today a major player in such a domain for which goals are reinforced in the intended Nationally Determined Contribution (iNDC) set in Paris during the 2015 United Nations Conference on Climate Change (iNDC Brazil, 2015). The Brazilian government has ambitious goals for the next years: reduce greenhouse gas emissions by 37% by 2025 and 43% by 2030, compared to 2005. To do so, one the commitments of the Brazilian iNDC is strengthen the Low Carbon Emission Agriculture Program (ABC) as the main strategy for sustainable agriculture development, including restoration of additional 15 million hectares of degraded pastures and enhancing 5 million hectares of integrated cropland-livestock-forestry systems (ICLF) by 2030.
Global (e.g Conant et al., 2017) and local studies (e.g Bogaerts et al., 2017, Oliveira Silva et al., 2016) show that pastures have potential to accumulate C in soil. However, these studies evaluated well-managed pastures, a quite different scenario from those commonly observed in Brazilian pastures. Brazil is the second biggest exporter of cattle beef and has the second largest herd in the world, only surpassed by India. Most of livestock production is grass-fed, extensive and spread in Cerrado, a biome which occupies an area of 204.7 million hectares in central Brazil. Pastures are the main land use in this biome, occupying more than 54 million ha. However, it is estimated that 60% of Cerrado pastures are degraded in some level (Andrade et al., 2014)
The relevance of pasture recovering and ICLF for soil C build-up and climate change mitigation suggests that this would be an efficient instrument for climate policy in Brazil. However, while the effects of Cerrado conversion to pastures in soil C has been already assessed by several studies (e.g Oliveira et al., 2016; Brito et al., 2019), the role of pasture recovering and ICLF remains largely unexplored by pervasive biome-scale analysis. Currently, is mandatory a comprehensive analysis of soil C stocks in areas under the management practices suggested by the ABC Program. Besides being critical to Brazil achieve iNDC commitments, such effort would be a useful tool for the evaluation of ABC Program and to encourage decision makers and planners to diffuse sustainable land use strategies and soil management systems. In this sense, this proposal aims to (i) quantify the soil C and N stocks, and isotopic composition in livestock areas under the management practices suggested by the ABC Program; and (ii) assess the contribution of soil C accretion in livestock areas to Brazil achieve iNDC commitments.
Methodology:
At least 10 study areas of improved pastures and integrated systems across Brazilian Cerrado will be chosen for sampling. This is a critical step of the project and areas selection will be carried out based on many criteria, such as localization, time since the adoption of the management practices suggested by the ABC Program and available information about land use. Areas with contrasting edaphic conditions (e.g soil mineralogy and texture) will be prioritized. As a pervasive proposal, we intended to encompass most conditions and spread our sampling across the whole biome, until it remains feasible.
A chronosequence approach will be used, comprising at least two land uses in each site: a reference, preferentially a degraded pasture, and an area of recovered pasture or/and ICLF. Chronosequences will be sampled because there are no long-term experiments that represent this scenario. The land uses will be located adjacent to each other, minimizing differences in climatic, topographic and soil characteristics. In each land use, soil will be sampled down to 1.0 m depth in five points, 50 m away from each other.
Soil C and N content and isotope composition will be determined using an elemental analyzer and mass spectrometer. Results will be expressed as δ13C and δ15N (‰) using PDB-Vienna as reference for 13C levels and air composition for 15N. The equivalent soil mass technique, which adjusts for different soil mass differences between land uses, will be applied to calculate C and N stocks. The rates of C stock changes associated with the adoption management practices suggested by the ABC Program will be calculated considering the difference in C stocks between the current management and a reference. For more information about stocks and C partitioning calculations, see Oliveira et al. (2016). Comparisons between land uses will be carried out using one-way ANOVA with land use type as the main factor and sites considered as blocks and treated as a random variable. The means between land uses will be compared by Tukey test (p<0.05).
Criteria of the candidate:
- PhD in environmental science, soil science, surface geochemistry, or related fields from a recognized morrocan or african university.
- At least one or two high publications record in international well-ranked journals
- Significant knowledge in environmental science studies, including experienced in soil field work and abilities in isotopic geochemistry techniques and modeling capabilities.
- Excellent verbal and written communication skills in English.
- Skilled in both field and lab work.
- Proactive, ethic, and respectful person
