extending the reach of crushed-rock fertilizer to africa · pdf filevery grateful to the sage...
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Civil Engineering and Geosciences • Cassie Building • Newcastle University • Newcastle upon Tyne • NE1 7RU • UK • www.ceg.ncl.ac.uk
further information:
Annock G. Chiwona, Rachel Gaulton & David A.C. Manning
Email: [email protected]
School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne, UK, NE1 7RU
The study’s methodology involves various
interrelated activities (Fig 3).
4. Malawi Nsy rocks compared with
other areas of world Literature shows high alkali content for
Malawi’s Nsy and similar geochemistry
with some countries (Fig. 4).
Nepheline syenites have no quartz and
show diagnostic emissivity features in
thermal infrared (TIR) region of
electromagnetic spectrum (Fig 5).
5. Initial results Some potential areas have been identified
using digital terrain model and preliminary
K count map (Figs 6 & 7).
6. Conclusion Malawi’s Nsy rocks show similar
geochemistry to other areas already tested
for fertiliser use. Remote sensing has
potential to identify their occurrence.
7. Acknowledgements Very grateful to the SAgE DTA, Terrativa and the Society
of Economic Geologists (SEG) for funding this study.
8. References Manning D.A.C. (2015) How will minerals feed the world in
2050? Proceedings of the Geologists' Association 126:14-17.
Sheldrick W, Syers JK and Lingard J. (2002) A conceptual
model for conducting nutrient audits at national, regional, and
global scales. Nutrient Cycling in Agroecosystems 62: 61-72.
Woolley, A.R. (2001). Alkaline Rocks and Carbonatites of the
World. Part 3: Africa. London: Bath.
1.Background Food security is one of key priorities of the
global community. However, food
sustainability is greatly affected by
depletion of soil nutrients especially
potassium (K) such that global production
of K fertilisers needs to be doubled
(Manning, 2015; Sheldrick et al., 2001).
Africa, with 15% of global population uses
just 1.5% of world's k fertiliser (Fig 1). The
cost of conventional K fertiliser is also very
high, hence the need for alternatives to
replenish soil K depletion (Manning,
2015).
2. Aims and Objectives
This study’s goal is to assess potential of nepheline syenites (Nsy) from rift tectonics, with initial focus on Malawi, as alternative K fertiliser sources.
The research project seeks to:-
Use satellite imagery to map
vegetation and surface mineralogical
indicators of weathering to release K.
Delineate nepheline syenites using
remote sensing and airborne geophysics
data.
Conduct groundtruthing for key
potential areas.
Assess K release through geo-
chemical sample analyses and plant-
growth tests.
Assess suitability of Malawi nepheline
syenites as K fertiliser.
3. Materials and Methods Remote sensing and airborne geophysical
gamma ray data were used to identify Nsy (Fig
2).
Figure 4: Nepheline syenites SiO2-K2O-Na2O ternary
plots for (A) Africa and (B) other parts of the world.
Figure 1: K nutrients soil depletion in African countries,
(data from Sheldrick et al., 2002).
Figure 2:(a) Remote sensing (http://geomatics-
tech.blogspot.co.uk/2013/09/) and (b) geophysical data
acquisition processes (http://crustal.usgs.gov/projects/)
Figure 5: Emissivity properties of some igneous rocks.
Figure 6: Digital terrain model showing some potential
areas of interest (circled) overlain with alkaline rocks
location (black dots) data from Woolley (2001)
Figure 7: K count map with potential areas identified
using remote sensing
Figure. 3: Flow chart of the methodology
Extending the reach of crushed-rock fertilizer
to Africa
TIR data is ideal for delineating nepheline
syenites
(a) (b)
Malawi