Key Themes: Agrogeology

The 'Key Themes' posts are a series of short articles outlining the role that geologists have in various aspects of global development.

Food security is a huge and emerging problem facing global development. Huge numbers of people are already undernourished, and world populations are expected to rise significantly over the next 40 years. Sustainable agriculture is fundamental to global development.

In Sub-Saharan Africa, estimates suggest that more than 50% of people rely on agriculture for their livelihood (Van Straaten, 2007) and in rural areas significant numbers are subsistence farmers – growing food to meet their family’s food requirements. Agriculture is a leading component of many developing economies. In Tanzania, for example, it is estimated that agriculture accounts for more than 40% of GDP and employs 80% of the workforce (CIA, 2011).

For agriculture to be sustainable, it must be done in a way that makes it possible to continue using the natural resource (the soil) over significant periods of time. The soil is the source of the nutrients needed for crops to grow, and agriculture to be productive. In many developing countries, soils are becoming rapidly depleted of the nutrients required for productivity, through over-exploitation, and soil quality is decreasing. For agriculture to be sustainable the import of nutrients must match or exceed the export of nutrients.

What role do geologists have to play in this sector?

Agrogeology is the application of geology to agricultural practice, examining how soil nutrients, pH and soil structure can be improved using naturally occurring, mineral-rich rock materials. Rocks such as potash, gypsum, limestone and dolomite are rich in nutrients and can be used as fertilisers – directly added to the soil. One of the biggest challenges is replacing and increasing phosphates in the soil. Geologists can play an important role in identifying, mapping and utlising phosphate-rich rocks. Rocks such as scoria and pumice can be used to help retain water in the soil, and rocks such as limestone and dolomite can be used to decrease the acidity of the soil, raising the pH.

A key text, Rocks for Crops, outlining the principles of agrogeology can be found here. It is written by Dr Peter Van Straaten, a leader in this field, who has kindly made it freely available for people to read and use.

See Also: Rocks for Crops – University of Guelph (Canada) Project headed by Dr Peter Van Straaten.

Photos: Volcanoes in Chile

The Severity of Climate Change

(c) AAAS 2011

As reported by the National Science Foundation (USA), the latest edition of Science (25th February 2011) includes a fascinating piece titled 'How Severe Can Climate Change Become?'

An international team of scientists led by Curt Stager of Paul Smith's College, New York have been examining cores of sediments derived from Lake Tanganyika, and other locations across Africa. These sediment cores can be used to produce models of past climate (palaeoclimate), giving an indication of what conditions were like tens of thousands of years ago.

Results of this research found that around 15-18000 years ago a megadrought occurred in which Lake Victoria (below right) dried as did other lakes and major rivers such as the Nile. The effects of this would be devastating for huge numbers of people. It is conjectured that the cause of this megadrought was a warming event, and the melting of huge amounts of ice, releasing significant amounts of water into the North Atlantic, altering global climatic patterns.

The report highlights that there is much less ice today that could melt and enter the North Atlantic, and hence it is unlikely that a megadrought on the same massive scale could occur, however the results give an indication of some of the effects global warming could have on developing nations such as Tanzania, Uganda, Ethiopia etc. Droughts much smaller than the megadrought reported in this paper do and will have a significant effect on the lives of many poor communities.

You can find the press release for this article here

Key Themes: Water Resources

The 'Key Themes' posts are a series of short articles outlining the role that geologists have in various aspects of global development.

One of the biggest issues in developing countries is access to clean water and good sanitation. Current estimates suggest that nearly 900 million people lack access to clean water, and 2.6 billion people lack access to good sanitation.

Water is essential for life, in cases where communities don’t have access to clean water they are forced to drink dirty and dangerous water. This water can cause serious illness, sometimes leading to death. Many communities have to walk several kilometres to collect their water – in some cases this water is clean, in other cases it is unsafe but the closest or only water source around.

A lack of access to clean water also has a direct impact on many other areas of development. Usually it is women or children who collect the water, meaning children miss school and lose out on their education. Women lose out on income-generating activities, as they are devoted to collecting water, they make themselves vulnerable by walking to often-isolated places alone, and are forced to carry large volumes of water on a daily basis.

What role do geologists have to play in this sector?

Geologists play a crucial role in the discovery, access and sustainable management of clean water supplies through the study and application of hydrogeology.

Hydrogeology is the study of the distribution and movement of water below the surface of the earth. Groundwater is often preferred to surface water as it is generally protected from contamination that can occur on the surface. As the water percolates through soil and rock the water is filtered to remove contaminants. It is also protected from the high temperatures, and thus evaporation, that is common in many developing countries.   

Most groundwater is derived from rainfall, with some also coming from surface water features such as rivers and lakes. A proportion of rainfall infiltrates the ground, percolating through soil and rock to form underground stores of water in a particular rock/soil unit (known as an aquifer). A geologist has a role in locating these aquifers, determining how much water is in them and whether it is safe to use, and how they can be sustainably exploited.

An understanding of the geology of an area can give an indication of where water resources can be located, where to drill for water, and how deep to drill. Techniques such as geophysics can also be used to provide additional information and is making a huge difference to the drilling of boreholes across developing nations.

Geology for Global Development

Geologists work on issues ranging from water and energy supply, natural resources, natural hazards and climate change - meaning they have a very important contribution to make to global, sustainable development. Geologists have a contribution to make to discussions and debates relating to international development, as well as generating solutions, ideas and resources to empower communities, help lift them out of poverty and support NGOs.

This blog will present articles about the role of geology in international development and direct you to appropriate websites and discussions. If you would like to post here, write an article on a particular topic or share a photo then please do get in touch.