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: a.g.chiwona2@newcastle.ac.uk

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