Assessement of elemental nutrients and of organic matter quality in cultivated lands of Rufisque-Lendeng:

16.07.13 Colloque sur la recherche actuelle à Dakar/ Senegal 1


Assessent of elemental nutrients and of organic matter quality in cultivated lands of

Rufisque-Lendeng

Jessica RobertsMaster Thesis in Biogeosciences


General Context

Lendeng When an accident leads to an idea


Lendeng

www.maps.google.ch, retrieved the 4.06.13

Rufisque

Lendeng


http://www.unep.org/groundwaterproject/Countries/Senegal/Report/DecReport_02.pdf , retrieved the 23.06.13

http://www.unep.org/groundwaterproject/Countries/Senegal/Report/DecReport_02.pdf


Study Field Conditions

● 2m x 7m of surface

● Lactuca sativa var. Eden

● 7 weeks to grow

● Irrigated with drinking water

● 14-36m depth of groundwaterTest Salad field (J.R.)


Problematic

Periurban AgricultureA green Lung or a land of new potential ?


Urbanisation

Street built in 2012 through Lendeng (J.R.)

District of Rufisque nearby the field of Lendeng (Haruka 2012.)


Irrigation


Food

security

Salad cultivation field of Lendeng (J.R.)


1. To observe the change in pedological process

2. Changes in soil solutions with depth and with time

Objectives


Method

Sample-TakingDifferent elements of soil


5 - 40cm


CERAMIC POROUS CUP

Constellation and Depth

50 10050 50 10050 50 50

20

40

70

Depth ( cm)

Distance ( cm)


Results

Soil profileThe frame of nutrient exchange


Granulometry


Mineralogy


Mineralogy

First Lithological Rupture


Mineralogy

Second Lithological Rupture


Mineralogy – Fine Fraction



First Lithological Rupture



Second Lithological Rupture



Third Lithological Rupture


Nutrielements

● Sodium● Potassium● Phosphate● Sulphur

GranulometeryOrganic Carbon

Acid elementsoriginally from clay or sand

Limestone

& Parameters linked with the presence of limestone

Magnesium

Fresh Organic Matter



Results

Soil Water and SolutionThe medium of nutrient transfer


Parameters showing a significant spatio- and time development

Time● pH

● Fluore– Bromure

– Sulphate

● Organic Carbon and Matter

Spatial● pH, Conductivity and

Quantity

● Soluble ions (except phosphat, calcium, ammonium, potassium)

● Organic Carbon and Matter


Horse Manure

Salad plantingUrea

NPK

1st Harvest

Nb leave 3 - 5 8 9 12 22

Length (cm 6 - 7 8 10 12 18



Chlorid

Sulphate


Ca2+ or Mg2+

M

Na+ or K+


M


13 =

Limit of a Sodic Soil

Brady and Weil, 2008


4 mS/cm =

Limit of a Salin Soil

Brady and Weil, 2008

mS

/cm


Water pH of Soil

> 8.5

Sodic Soil


Conclusion

Assessment of nutrient fluxWhat is the future of the soil ?

● Soil→ A complex construction of two or more soil

layers

● Soil solution

→ Indicating an important variation with depth

→ Nearly no variation with time

→ Signs for sodification process (High evaporation rate and Presence of Na in surface)


Thank you for your attention!


References

www.carte_du_monde.net, retrieved the 3.01.12

Félix, J. (2006). Caractérisaton des eaux d’arrosage, de leurs impacts sur l’environnement et techniques d’épuraton extensive par lagunage (Dakar, Sénégal). Travail de diplôme sci. nat. environ. Univ Lausanne et Univ. Genève, 114p.

Gobat JM, Aragno M, Matthey W (2010). Le sol vivant : Base de pédologie – Biologie des sols. 3 Editon, Presses polytechniques et universitaire romandes, 3.11, pp. 84-86 et pp. 371-395.

Hitz C. (2012). Synergie ou concurrence entre la vielle et son environnement : Renforcer les synergies entre la ville et l’agriculture à Dakar. Université de Lausanne, Urbamonde Genève.

IAGU (Insttut de l’agriculture et geston urbaine) (2011). Le maraîchage urbain à Lendeng (Rufsque, Sénégal). Rapport et poster, Insttut Africain de Geston Urbain), Juin 2011.

INRA (2006). Système de prélèvement de la soluton du sol par bougies poreuses, INRA Avignon, Unité des Sciences du Sol,

www.maps.google.ch, retrieved the 7.01.12

SPS (Sahel People Service) (2010). Centre d’AFAFA. www.sahelpeopleservice.com, consulté en octobre 2012

Brady, Nyle C, and Ray R Weil (2008). The Nature and Properties of Soils. Upper Saddle River, N.J.: Pearson Prentce Hall.


Salinisation and Sodification


Method

Ceramic Porous Cupsor how to capture the (soil) solution


Development of Condensation Indexin Soil Solution (SS) and Water Extracted Soil

Solution

Deeper Layers


Development of Condensation Indexin Soil Solution (SS) and Water Extracted Soil

Solution

Upper Layers


Method

Ceramic Porous Cupsor how to capture the (soil) solution

Lifestyle

Assessement of elemental nutrients and of organic matter quality in cultivated lands of Rufisque-Lendeng: