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Partnerships for enhanced engagement in research (PEER) SCIENCE
Cycle 2 (2012 Deadline)

Rhizosphere biology of shrub-created resource islands of Sahelian agroecosystems: optimization and adaptation to climate change

PI: Yacine Ndour (Institut Senegalais de Recherches Agricoles)
U.S. Partner: Richard P. Dick (The Ohio State University)
Project Dates: August 2013 to July 2016
2-432MicroTrop 2014 Field trip to Niayes' Small Farmer Vegetable Production
 MicroTrop 2014 Field trip to Niayes' Small Farmer Vegetable Production.
A major challenge facing Senegal is the capacity to feed a rapidly growing population against a background of climate change and low inherent soil fertility. Scientifically validated agricultural systems are now urgently needed that optimize crop productivity despite water and heat stresses. With previous support from the National Science Foundation, the collaboration to date between the Senegalese and U.S. scientists working on this PEER Science project has led to the discovery of two previously unrecognized shrub species that can coexist with crops on smallholder farms and have the ability to lift water from wet sub- to dry surface soil and to improve the soil. The primary goals of this new project are to understand how the harboring of beneficial nematodes (microscopic roundworms) and arbuscular mycorrhiza fungi (AMF) by shrub roots and associated rhizosphere can increase or maintain crop productivity in a climate change scenario of greater water and temperature stress. The project will be mainly based on lab experiments in a climate chamber with humidity and illumination to generate varying climate scenarios.

The main expected outcome will be progress toward developing optimized shrub-crop systems that will help subsistence farmers withstand climatic change stress. The project should serve USAID strategies of (1) adapting agricultural systems to increase, or at least, maintain crop production in climate changes while preserving biodiversity and related services at field scale, (2) creating wealth through better management of Senegal’s natural resources and development of sustainable agriculture, and (3) strengthening institutional and human capacities in the fields of agricultural education and research that benefit to smallholder farmers.

Summary of Recent Activities

The period between July and September 2015, the team's focus was on a new activity related to their objective 1 of the project, which was to study the Dynamic of C and N mineralization and soil microbial activities and communities of semiarid Sahelian soils amended with native shrub residues under elevated temperature.

The specific objectives were to investigate the effects of shrub residue type (fine or coarse) on C & N mineralization and soil microbial activities under elevated temperature .

The methodology was: The soils for lab incubation study, were collected from a field experiment that started in 2000 at Thies (13°45 N, 15°47 W) in the Sahelian area of Senegal at a height of 18 m above sea level. The area has a mean annual rainfall of 450 mm from July to September and mean soil temperatures around 30°C.

A factorial design (2x3x4x4) experiment was conducted with 4 replications. Pot with 100g of soil were incubated with 1g of shrub residues 1% (w/w) with different temperatures for 5 months according to the
field practices with fine and coarse shrub residues. The team then set up the treatments as follows:
- Soil from Keur Matar beneath and outside the influence of shrubs (0-10 cm depth)
- 2 levels of air temperature: Ambient soil temperature (32°C) and+5°C (37°C) above soil temperatures
depending on the soil temperature at the rainy season (37°C)
- 3 levels of amendment was set up as fallow:
1) Bare soil without amendment
2) Soil + Shrub residues with less than 5 cm of length (Guiera)
3) Soil + Shrub residues with more than 5 cm of length (Guiera)
4 destructive analysis at Day 0, Day 60, Day100 and Day 150 (based on previous analysis Founoune-
Mboup et al., Unpublished data)
Then lastly, 4 replications was set up for each treatment

The experiment is ongoing and will end in January. The team will then pursue with lab and data analysis.

2-432 PhD student experiment in the greenhouse 2-432_ MicroTrop 2014 Participants and Lecturers.jpg
A PhD student conducts soil experiments in a greenhouse (photo courtesy of Dr. Ndour). MicroTrop 2014 Participants and Lecturers

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