In many countries in Sub-Saharan Africa (SSA), the growth rate of agricultural production is insufficient or barely enough to keep up with population growth. Agriculture can be made much more productive through sustainable intensification: increasing production per hectare without harming the environment.

The first requirement for increased production per hectare is integrated soil fertility management based on two pillars: soil improvement and the use of fertiliser. This statement immediately touches upon a common misunderstanding.

It is not rare for agroecology and regenerative agriculture advocates to oppose fertilisers and organic matter. While this is not completely untrue, it is also misleading. Yes, fertilisers can contribute to the breakdown of organic matter, but if fertilisers and organic matter are combined in appropriate proportions, they can enhance each other's effect. Indeed:

  • when fertilisers increase production, greater quantities of higher-quality crop residues become available as a result, which can be utilised for organic matter supply in the soil;

  • conversely, fertilisers have the best results on soils with sufficient organic matter.

In this way, the regrettably frequent downward spiral in productivity can be reversed into an upward one.

In order to make the most of improved soil fertility, better seeds are required.
However, a nuance regarding nitrogen should be remarked upon; this does not always require nitrogen fertiliser, because leguminous crops such as groundnut, cowpea, pigeonpea and several beans can extract nitrogen from the air with the help of bacteria. But in doing so, the yields will typically be lower than can be achieved with nitrogen fertilisers, while in addition, more and expensive phosphate is needed.

How can SSA agriculture improve the fertility of its soils? This can be done in two ways. First, by using more organic matter, especially from crop residues, animal manure, suitable compost, and perhaps biochar (a charcoal-like substance)1.

The limiting factor here is often animal manure. Many SSA countries have a shortage of manure due to the low livestock density. An additional factor is that farmers use their crop residues as animal feed where possible because these countries do not, like the Netherlands, import animal feed. Crop residues are thus not used directly as fertiliser and soil conditioners. Such use only becomes possible with higher production, where more crop residues of better quality also become available, i.e. as a result of intensification.

Moreover, in that case, the quality of animal manure will increase.

Dierlijke mestAnimal manure, Henk Breman

This leads to the second way to improve soil fertility: extension of the use of artificial fertilisers. Or - much better - a combination of fertiliser and animal manure at the same time. For instance, on mixed farms that are intensifying their arable production. These farms cannot just increase their crop production but also produce more and better by-products and thus animal feed and manure. By-products include straw, legume foliage, cottonseed and cotton oilcakes as well as the husks of cassava and yam. In addition, in many places there is a need for lime; one-third of African soils are too acidic while the use of certain types of fertilisers results in stronger acidification.

In order to make the most of improved soil fertility, better seeds are required. Seeds of crops that, when well supplied with nutrients, produce higher yields and are also more resilient in the face of climate change, diseases, and pests. In this regard, not only seeds of cash crops for export should be considered, but also seeds of staple crops produced for domestic food supply. For instance, there is much room for improvement in a crop like millet; in the case of pearl millet, the harvest index (the proportion of biomass that can be harvested) is still very low for a cereal. On India's initiative, the UN has declared 2023 as the International Year of Millets.

What policies are needed to achieve this?
Governments in SSA can encourage such developments in many ways2:
  • developing an infrastructure for fine-meshed soil testing and advice that helps farmers identify soil nutrient deficiencies, limited soil organic matter and harmful pH levels;

  • investing in organic matter recycling: in addition to recycling crop residues such as straw, much can be gained by adequate processing of food waste and other organic waste in villages and cities. For this, an active role by the government is indispensable, as organic matter is less likely to increase production in the short term than artificial fertilisers;

  • investing in the production, distribution and use of soil conditioners including lime;

  • adjusting, where necessary, applicable land-use rights and conventions in such a way that they provide farmers with more security of use and thereby no longer inhibit but rather encourage investment in soil amendments;

  • for countries with rich existing or potential energy resources (not just fossil resources, but especially hydro, solar and wind): investing in a national fertiliser industry. Where possible, the production of ‘green’ fertiliser should be prioritised, following the example of Angola which is planning to produce fertilisers using hydropower3. This can also contribute to SSA's food sovereignty;

  • abolishing import duties and taxes on fertilisers, which are being still applied by one-third and half of SSA countries, respectively. Abolition of these levies will make fertiliser more affordable for farmers4;

  • investing in improving the fertiliser market. Aspects to consider are building trade networks, introducing, and enforcing quality standards and training buyers in government brokering and cooperatives. To drive demand, vouchers for farmers to buy fertiliser and seed could also be considered5;

  • investing in nutrient recycling through ecological sanitation (ecosan) in a safe way, phosphate, potassium and - where possible - nitrogen from urban sewage and returning those to the field.

Agricultural extension services can also be effective, but how effective depends strongly on the context. Public agricultural extension services have been privatised in many countries as part of Structural Adjustment Programs since the 1990s. Those neoliberal programmes were more or less enforced by the World Bank and the IMF. Privatisation provided ample scope for commercially driven extension agents with their inevitable bias. Currently, there is a renewed need for independent extension, not only by experts, but also farmer-to-farmer, as advocated on Foodlog by Nigerian columnist Babatunde. Digital information also offers great opportunities, provided it is not commercially driven. But what is important to remember; extension is often only effective in an enabling environment with sufficient certainty of land use and well-functioning markets, including quality control, for affordable inputs (fertilisers, seeds, tools, etc.) on the one hand, and sales of the extra agricultural products produced on the other. In those markets, the power of middlemen and other traders needs to be limited.

How can the Netherlands and the EU contribute to this?
The Netherlands and the EU can contribute to this development, in addition to what they already doing, by supporting SSA countries with knowledge, technology and, if necessary, co-financing investments in:
  • the aforementioned infrastructure for soil research and advice;

  • independent agricultural extension services. Agriterra and Solidaridad are already active in this in several countries in SSA, including farmer-to-farmer extension;

  • better utilisation of organic matter for soil improvement;

  • research into the usability and effects of biochar6. As biochar can sequester carbon over the long term, there may be opportunities for a link with European emissions trading;

  • market development for fertilisers, lime, and seeds. In the past, the Netherlands has supported the Economic Community of West African States (ECOWAS) through the International Fertiliser Development Centre (IFDC), to develop a regional market for inputs. This has led, among other things, to improved laws and regulations for that market;

  • ‘green’ fertiliser production;

  • ecological sanitation;

  • plant breeding aimed at a wide range of crops with higher yields and greater resilience to drought, diseases, and pests. In this area, the Netherlands has been a frontrunner, often in collaboration with African partners. Through East-West Seed, much has already been done to improve vegetable seeds for smallholder farmers. Founder Simon Groot was awarded the World Food Prize for this in 2019. These efforts deserve vigorous continuation and broadening, if possible, including the cereal crop millet. Resilient crops need less pesticides, which may benefit the health of farmers and consumers. Cash crops such as mangos, that have undergone less treatments, also provide better opportunities for export to the EU.

While discussing all this, let us keep in mind that not everything stands or falls with well-functioning governments. And that is just as well, because in Africa and elsewhere, governments by no means always do what can be expected from them and it may be pointless to wait for that
Final remarks
While discussing all this, let us keep in mind that not everything stands or falls with well-functioning governments. And that is just as well, because in Africa and elsewhere, governments by no means always do what can be expected from them and it may be pointless to wait for that. Mutually beneficial investments are possible on a commercial basis as well. Let’s take crop breeding in the Netherlands as an example. A commercial player such as Holland Greentech, in which Rijk Zwaan and Koppert participate, among others, offers a variety of horticultural services in several countries, from soil analysis and soil fertility management to improved seeds, irrigation, greenhouses, integrated pest management and information and training. Let’s further consider value chains from Africa to the European market. In addition, cash transfers (remittances) from Africans in the diaspora can help small farmers and entrepreneurs finance investments.

The one thing the EU and European market players had better not do, is impose rigid agro-ecological requirements on products from Africa. While agroecology in itself is invaluable, if it excludes artificial fertilisers, it will put a brake on the development of African agriculture. For widely impoverished soils, fertilisers are often as indispensable as is organic matter.

A series of five

In three previous articles (click on the links for articles 1, 2 and 3), Henk Breman and Wouter van der Weijden outlined what African countries can do about sustainable intensification. In a fourth article, the same authors, joined by Niek Koning and Monique Calon, explored what policies are needed for this and what the Netherlands and the EU can contribute. In doing so, they identified two priorities: in general, a stimulating agricultural policy and in particular a policy aimed at improving soil fertility. They focused on a stimulating agricultural policy. In this fifth article, Henk Breman and Wouter van der Weijden, supported by Ken Giller, focus on soil fertility.

About the authors:
Henk Breman is an agrobiologist with long-term research experience in several African countries and author of the book From fed by the world to food security - Accelerating agricultural development in Africa (2019).

Wouter van der Weijden is an environmental biologist and director of the Centre for Agriculture and Environment Foundation.

Ken Giller is Professor Plant Production Systems at Wageningen University.

The last two articles in this series, summarised in six points
  1. Sub-Saharan Africa has great potential to increase the productivity of its agriculture, and this is sorely needed given rapid population growth and declining food security and sovereignty. First and foremost, this requires stimulative agricultural policies in general and in particular enhancement of soil fertility.

  2. Incentive policies would focus first on stable prices that should be high enough for viable farms to cover their costs. This may require import tariffs. But because tariffs could also lead to higher food prices, flanking measures are then needed to ensure that food remains affordable for the poor. Possible ways of ensuring that are job creation projects, work-for-food programmes, school meals, food banks and cash transfers. Such measures can be co-financed from the revenues of the levies. Furthermore, farmers and consumers both benefit from investments in better, independent market information, including availability through mobile phones.

  3. Investments in transport and storage infrastructure could also benefit both farmers and consumers. In addition, it is important to promote viable farms. This requires strengthening land use rights, on the one hand, and developing non-agricultural employment, especially in industry, on the other. Sectors to be considered are fertilisers, food processing, textiles, and energy (especially solar and wind).

  4. The Netherlands and the EU can actively support said developments, by adapting their trade policy and by supporting necessary investments with knowledge, technology, and co-financing.

  5. Special attention is needed for improving soil fertility. This requires integrated soil fertility management with more organic matter and lime on the one hand and more artificial fertilisers on the other, which also produce more crop residues and thus more organic matter as a by-product. Governments can promote this improvement process by abolishing import duties on fertiliser, developing their own, preferably "green" fertiliser industry and investing in recycling nutrients from villages and cities.

  6. Here too, the Netherlands and the EU can play an active role, among other things by supporting the necessary investments with technology and knowledge and by co-developing better seeds. There are mutually beneficial opportunities there.

Some of the policy options mentioned can already be found in the opinion "Urgency of a new Dutch Africa Strategy" of July 2022 by the Dutch Advisory Council for International Affairs (AIV) and also in the letter of the Dutch Ministers Schreinemacher and Adema "Global Food Security Roadmap" of December 2022. All options mentioned deserve at least consideration in the new Africa strategy that the Dutch government is currently preparing and in the debates that will follow to discuss this. Indispensable in this regard are a long-term vision and a government policy that provides coherence between development policy and trade policy of both the Netherlands and the EU.

1. Biochar is made by heating organic material beyond 350°C under oxygen-free conditions. This process is called pyrolysis. Biochar can be made from a variety of organic feedstocks, including crop residues, manure, wastewater residues and wood. Interest in biochar has increased in recent years because it can sequester carbon in the soil over centuries or even millennia. Biochar generally increases crop yields, especially in nutrient-poor tropical soils. It also reduces fertiliser leaching and emissions of the biochar gas N2O (nitrous oxide). For a comprehensive scientific review that includes other potential benefits, see: S. Joseph et al. How biochar works, and when it doesn't: A review of mechanisms controlling soil and plant responses to biochar. SCI Bioenergy 2021;13: 1731-1764.
2. See also: H. Breman (2023). Africa's fertiliser and soil health action plan - An African green revolution. Fertiliser Focus 40 (1): 36-40.
3. The Advisory Council on International Affairs (AIV) wrote last year in its advice Urgency of a new Dutch Africa strategy: "Support with technology the production of fertiliser in African countries where there is gas. But above all work on applying fertilisers that do not harm the soil." By the way, the council forgot to mention green energy.
4. Countries that produce their own fertilisers or want to invest in those could introduce or continue temporary import tariffs to protect their domestic market. This is possible as long as the African Union does not apply tariff walls at its common external borders, a policy we argued for in the previous article.
5. H.L. Wong et al. Effects of input vouchers and rainfall insurance on agricultural production and household welfare: Experimental evidence from northern Ethiopia. World Development (2020): 105074. For more information see also this article, this publication and this website
6. Wageningen conducts laboratory research on biochar, among other things. The Cooperative Association Fairchar is active in Africa with the Carbon2Soil plan.