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Saving African soils: grounds for hope?

500 million hectares of farmland in sub-Saharan Africa are moderately or severely nutrient-depleted. (World Bank)
500 million hectares of farmland in sub-Saharan Africa are moderately or severely nutrient-depleted.
World Bank

At the recent launch in Nairobi of a new digital map showing soil depletion in Africa, soil scientists decried poor rates of fertiliser application in the continent. Five hundred million hectares of Africa's agricultural land is moderately or severely mined of life, it was reported, yet farmers apply only ten percent of the required soil nutrients to support food production.

Soil scientists in Africa and beyond are now convinced that investments focusing on depleted soils are vital to achieve a turn-around in agricultural productivity. Through the African Soil Information Service (AfSIS), remote satellite imagery and on-the ground efforts will be used to document, analyse and distribute soil data. The service will also establish systems for consistent evaluation of key soil properties, such as its capacity to provide nutrients and hold water.

In Points of view, soil and fertiliser experts share their views on how African soils can be saved.

Sharing information on soils

With the right use of extension staff, Africa can increase fertiliser use from 20 to 60 per cent. This will make a very big impact. Africa needs information and scientific evidence on good fertiliser use.
Nteranya Sanginga, director of the Tropical Soil Biology and Fertility Institute of the International Centre for Tropical Agriculture (TSBF-CIAT), Kenya

Kenya will benefit from more efficient use of fertilisers. Soil data provided in the past has not been adequately used. We need to make the digital soil maps more user-friendly such that they are easily understood by extension staff. The information can indeed help us understand our soils better and know what's to be done to ensure sustainability.
Wilson A Songa, Agriculture Secretary, Ministry of Agriculture, Kenya

We need to train agro-dealers on making appropriate recommendations. Sometimes we need to back it up by soil testing, so that they know, for example, that in this district the soil is low in nitrogen, it is low in phosphorus, or it is low in potash. Then they should be able to tell the farmers what amount of fertiliser they will require so that they will get optimum yield of whatever crop they are growing.
Francis Tetteh, senior research scientist, Soil Research Institute, Ghana

On small-scale farm plots, organic fertiliser may be sufficient to provide nutrients and maintain soil health. On large areas, chemical inputs are likely to be needed. (World bank)
On small-scale farm plots, organic fertiliser may be sufficient to provide nutrients and maintain soil health. On large areas, chemical inputs are likely to be needed.
World bank

There is a high need for fertiliser plants in Africa. When you buy fertiliser from Asia or Europe, port charges and sea-haulage costs as well as local transport make fertilisers more than double their original price. With rising fuel prices, this makes affordability a very big problem. This can be dealt with at the policy level where governments could waive taxes, provide special tariffs and give port rebates to transporters, or implement local fertiliser plants.
Peter Okoth, project information manager, TSBF-CIAT, Kenya

Exploiting natural mineral reserves

Apart from the existence of natural deposits of the key raw materials for producing fertilisers - over 75 per cent of rock phosphate deposits in the world are found in Africa - labour is also relatively cheap.
Jonas Chianu, TSBF-CIAT

Tanzania has a natural reserve of rock phosphates - minjingu - which can be used to process synthetic phosphates. There are also other potential raw materials for fertiliser production: diatomite deposits in Kenya also seem to have important nutrients for crop growth and development which should be investigated further.
Peter Okoth, project information manager, TSBF-CIAT

The overriding constraint in African soils is organic phosphorus. The minjingu reserve in Tanzania provides an opportunity for the continent to exploit local resources to increase access to affordable fertilisers for its farmers.
Keith D Shepherd, principal soil scientist, World Agroforestry Centre, Kenya

Financing for fertilisers - credit, vouchers and availability

For Africa's very poor farmers, even if the banking system was working, they can't really afford to get credit. For those, you need smart subsidies on seed and fertilisers supplied through the rural input shops. But for others, you work with banks. And AGRA for example, is working to give loan guarantees so that banks can lend to farmers and agro-dealers, and we try to reduce the rate of interest that banks charge them.
Akin Adesina, vice president, policy and partnership, Alliance for a Green Revolution in Africa (AGRA)

Like the success stories in Malawi, the voucher system must now be considered by African governments. The system has also been practised in the US under the Contracted and Early Payment System where producers are paid 50 per cent of a crop's anticipated value at maturity. For Kenya, the National Cereals and Produce Board could pay farmers 50 per cent of the value and recoup the sum at the harvest season.
Peter Okoth, TSBF-CIAT

African governments must address nutrient depletion if the current food crisis is to be solved. (World Bank)
African governments must address nutrient depletion if the current food crisis is to be solved.
World Bank

The main problem is that most of our agro-dealers do not have enough money at the time when fertilisers are cheap on the international market, so they are not able to stock enough fertiliser before the rains start. If we had enough demand from the farmers, if farmers were well-organized, they would be able to give the agro-dealers an effective demand, and the agro-dealers would have the confidence to supply the fertiliser.
Vincent Wandale, principal business officer, Ministry of Agriculture, Malawi

The problem is actually getting fertilisers to the rural areas. That is why we have to first change the farmers, put them in groups, what we now call farmer based organisations. Put them in groups, and train them well to know the importance of fertiliser.
Francis Tetteh, Soil Research Institute

There are ongoing efforts led by the African Development Bank (ADB) to reduce logistics costs that make fertilisers very costly in Africa.
Namanga Ngongi, president, AGRA

Top-level lobbying and policy dialogue are being used, based on the conviction that a move towards reducing hunger on the African continent must begin by addressing its severely depleted soils. Improving the overall fertiliser procurement process could reduce the price of fertiliser in sub-Saharan Africa.
Jonas Chianu, TSBF-CIAT

Increasing efficiency of crops and inputs

A lot of work has been done on micro-dosing in West Africa, with very good results as well. Many of these initiatives are isolated attempts, but there are some attempts to scale this out.
Jeroen Huising, TSBF-CIAT

You should firstly be able to identify nutrient-efficient crop varieties. Then you have to target the application carefully such that you give it in small doses over a period of time. Of course you must also understand the biology of the crop, that at a particular time, whether you apply it or not, it will not take it up. So this kind of training must go along with the technology.
Lawrence Narteh, senior research scientist, Crop Research Institute, Ghana

Farmers in Africa only use 10 per cent of the fertiliser needed to maintain adequate food production. (WRENmedia)
Farmers in Africa only use 10 per cent of the fertiliser needed to maintain adequate food production.

There are some small initiatives that specifically look at appropriate fertilisers. Mavuno, for example, combines macro and micronutrients and farmers report to have very good results with it.
Jeroen Huising, TSBF-CIAT

There are many cases where soils require organic amelioration first before responses to mineral fertilisers can be obtained. Finding ways to identify such soils through soil tests and mapping these soils is a high priority. It is also important to identify soils that have inherent constraints so that these constraints can be corrected before encouraging farmers to use inputs such as improved seeds and nitrogen fertilisers.
Keith D Shepherd, World Agroforestry Centre

The question is really, how do we get nutrients in the system in an effective and economic way? The solution will be integrated systems where you combine fertiliser input with other sources of nutrients: organic matter, but also the use of rhizobia to fix atmospheric nitrogen, together with measures to stimulate root development and use of mycorrhizae that may enhance nutrient uptake of the plants.
Jeroen Huising, TSBF-CIAT

High priorities - investment and effort

The strategy will very much depend on the local conditions. There is no specific technology that is applicable everywhere. So, further development and adoption of these technologies by farmers will require massive investment and coordinated effort.
Jeroen Huising, TSBF-CIAT

The capacity of soil science in Africa is going down. Labs that exist do not function. Some countries lack capacity to give this knowledge. Soil management in sub Saharan Africa must be improved dramatically if we are to reduce poverty, feed growing populations and cope with the impact of climate change on agriculture. Achieving this requires accurate, up-to-date information on the state of Africa's soils.
Nteranya Sanginga, TSBF-CIAT

Comments collected by Zablon Odhiambo, Kofi Adu Domfeh and George Kalungwe

Date published: March 2009


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