LAST week, 650 people from 80 countries gathered in Germany for a week-long conference that brought together scientists and environmental advocates to discuss climate change’s increasingly hottest topic – soil.
Soil is one of the most important resources we have, if not the most important. It sustains all our agricultural and livestock food production, wood for fuel production, filters water so that we can drink it and fish can live in it. We also use it for construction – therefore it sustains our homes and infrastructure.
Despite this, soil is endangered. The UN estimates that nearly a third of the world’s soil is degraded and in sub-Saharan Africa, that figure is closer to two-thirds. To draw attention to this incredibly large issue, 2015 was dubbed the “International Year of Soils”.
In Africa, the issue of land degradation (a decline in land quality caused by human activities) and soil fertility decline is deeply complex with intertwining and cyclical causes. These range from poverty, inadequate farming techniques, poor inherent soil qualities to population pressure, to insecure land tenure and climate change, amongst other factors.
If these are issues are not addressed the cycle of poor land management will result in higher barriers to food security, agricultural development for smallholder farmers and wider economic growth for Africa.
In fact today, the economic loss as a result of land degradation is estimated at $68 billion per year and according to Agriculture for Impact (A4I), an independent advocacy initiative, better land management practices could deliver up to $1.4 trillion globally in increased crop production – 35 times the losses.
The usual suspects
So which African countries should be on a “soil watchlist”?
In terms of soil degradation, the usual suspects would be the dry land African countries around the Mediterranean and Middle East – but in actuality, degradation (measured in terms of its net primary productivity) here was represented by only relatively small areas in the Maghreb and the Nile delta.
A 2008 report on the “Global Assessment of Land Degradation” by the Food and Agricultural Organisation (FAO) and partners offered some shocking insights and surprises into the degree of soil degradation in some African countries.
Sifting through global statistics between 1981-2003, it turns out that 34 of Africa’s 54 countries reported over 20% in either the amount of land degraded or the amount of population affected by land degradation.
In more than seven African countries, half their population was affected by land degradation, and in nine countries over half their land area was affected.
The countries with the largest percentages of their territories affected were; Swaziland (95.22%), Angola (66.2%), Gabon (64.58%), Zambia (60.41%) and the Congo (58.95).
The countries with the highest percentage of their populations affected were; Swaziland (98.77%), Angola (60.74%), Djibouti (59.3%), Congo (54.93%) and the Democratic Republic of Congo (53.49%). These results show that it is not necessarily high population density that is related to land degradation, but rather what a population does to the land that determines the extent of degradation.
A factor that must be considered when ranking which countries should be on the soil watchlist is the rate of soil nutrient depletion. Soil nutrient depletion is an important concern directly linked to food insecurity in developing countries due to the intensification of land use for agricultural production.
In fact, it is estimated that nutrient depletion accounts for about 7% of the agricultural share in the average Gross Domestic Product (GDP) of sub-Saharan Africa, with national values ranging up to 25%!
In some cases, notably in the East African highlands, the rate of depletion is so high that even drastic measures, such as doubling the application of fertiliser or manure or halving erosion losses, would not be enough to offset nutrient deficits.
Heavily affected countries include; Burundi, Rwanda and Kenya. This could be in part due to the high altitudes, which have been for many centuries favourite settlement areas because of a relatively healthy, mild climate and sufficient rains. Erosion has also certainly been a cause of major nutrient depleting in this area.
In terms of nutrient depletion, other concerning cases include Tanzania, Mozambique and Niger where nutrient depletion accounts for up to 25% of the Agricultural Gross Domestic Product.
One of the most worrying cases today however is Ethiopia. Over one-quarter of the country’s land is degraded, affecting about 20 million people, almost a third of the total population.
To make matters worse, according to agriculture for impact, Ethiopia has one of the highest rates of soil nutrient depletion in sub-Saharan Africa. To address this, under Ethiopia’s five year growth and transformation plan, there is a dedicated sustainable land management project that focuses on the conservation of soil and water in arid zones. However, an estimated $8 billion is still required over the next ten years, in particular for irrigation development.
The science behind it
It should be noted that estimates of land degradation vary widely. According to Agriculture for Impact, while early estimates were largely subjective, in recent years the advances in remote-sensing and satellite technologies have enabled efforts such as the Global Inventory Modelling and Mapping Studies to measure vegetative growth at a resolution of eight km2. This has been used, with various weights and corrections for local conditions, by the team at the Center for Development Research (ZEF) at the University of Bonn to provide a worldwide measure of land degradation “hotspots”.
http://mgafrica.com/article/2015-05-05-saving-our-soils
