Green Synthetic Fertilizer in Africa: Boost for Sustainability or Aberration?

The role of agriculture in sustainable development can hardly be overstated: Agriculture is the largest user of land/soil and water, threatens biodiversity more than any other sector and is one of the largest emitters of greenhouse gases, especially when deforestation for new farmland is included. But it is also the source of almost all our food and the most important source of income in low- and middle-income countries. Climate change, degradation of natural resources and loss of biodiversity in turn jeopardize agriculture and thus economic development, the fight against poverty and food security.

Against this backdrop, it is understandable and appropriate that the “right” type of agriculture and the broader agricultural economy (comprising upstream and downstream economic sectors and the food industry) are the subject of controversial debate, especially as agriculture varies greatly depending on the region of the world and often even within very small locations. Nevertheless, in some debates there seem to be only two types of agriculture: Conventional, also known as industrial, and ecological or organic –the destroyer on the one hand, the healer on the other.

A new facet of this debate concerns the use of “green” synthetic nitrogen fertilizers in plant production. This is not a marginal issue, but concerns the core of the agricultural sector, as nitrogen is the most important plant nutrient and probably the most important driver of rising crop yields in agriculture – it is estimated that around 40 percent of the increase in global crop production is due to increased nitrogen fertilization. And a particularly relevant part of the debate for development policy is whether this green nitrogen fertilizer is a sensible, sustainable option for small farmers in the Global South, or another aberration of industrialized agriculture. This part of the debate in particular will be explored here.

How does nitrogen get into agriculture?

In traditional and organic agriculture, nitrogen mainly comes from the use of nitrogen-fixing plants (legumes, e.g. beans, peas, but also a number of shrubs and trees). These organic fertilizers can also be described as farm fertilizers. The majority is produced internally. In many countries of the Global South, shifting cultivation or fallow farming always was and is still practiced today to maintain or restore soil fertility and yields. Exhausted areas are left fallow, nitrogen is enriched via wild or cultivated legumes, animals may be allowed onto the fallow land, and only after some time is the area brought back into cultivation. Depending on the availability of land and the regenerative capacity of the soil, a fallow period can last from years to decades.

In conventional agriculture (with the exception of intensive livestock farming, where liquid manure plays the main role) the largest contribution of nitrogen by far comes from so-called synthetic nitrogen fertilizers, which are produced from atmospheric nitrogen using considerable amounts of energy. It is estimated that around two percent of global energy consumption is used for fertilizer production. As the energy for this has so far come largely from fossil fuels, releasing large quantities of the greenhouse gas carbon dioxide, their manufacture itself can be regarded as ecologically dubious.

So-called “green” synthetic nitrogen fertilizer is produced using renewable energy, the production of which generates no or significantly fewer greenhouse gases – with green hydrogen as the starting point, with a number of possible procedures, some of which are still being tested. As is the case with green hydrogen, the production of green synthetic nitrogen is largely climate-neutral, with publications stating greenhouse gas savings of 40 to 90 percent, a range that often appears to correspond to the position of the authors in the sustainability debate. In terms of climate impact, the production of green synthetic nitrogen fertilizer is therefore significantly more environmentally friendly than conventional nitrogen fertilizer. Just in terms of the energy balance, it is therefore a compelling proposition – it can save one to two percent of global fossil energy consumption and thus greenhouse gas emissions.

Greenhouse gas footprint is not the whole story

However, problems in the use of synthetic nitrogen fertilizers are generally not restricted to its production: There are also a number of sustainability concerns in its application. These comprise two areas: numerous negative ecological effects on soil, climate, water and biodiversity; and socio-economic effects such as a lack of yields and thus a poor or even negative cost-benefit balance, including economic dependencies.

No attempt will be made here to clarify this debate comprehensively. However, a few principles should be highlighted to help better classify the arguments, as gross simplifications and comparisons are often used.

Firstly, the ecological dimensions:

Greenhouse gases: Some of the greenhouse effects resulting from the use of nitrogen fertilizer is produced after field application. Some authors speak of up to 60 percent of the total effect. Biological conversion processes in soil and water produce nitrous oxide (N₂0), also known as laughing gas, an extremely potent greenhouse gas. The problem increases with the amount of nitrogen fertilization, especially with an excess that plants cannot absorb. This applies to both artificial and farm fertilizers. In addition, the problem depends crucially on temperature, soil type, soil life and, last but not least, soil management – in other words, when and how the nitrogen gets onto and into the soil.

Water pollution: The main water pollutant is nitrate (NO₃), which is also formed in the soil depending on the type and application rate of nitrogen fertilizer, site factors and cultivation and is leached into surface or groundwater. This poses a particular risk of over-fertilization of water bodies and even their ecological collapse. This pollution varies greatly from region to region, but is so serious that it is classified as one of the most important threats to planetary boundaries.

Soil fertility: It is often claimed that nitrogenous artificial fertilizers are harmful to soil fertility in themselves. This is not supported by the current state of research. There may be studies according to which unbalanced fertilization or the use of certain forms of nitrogen fertilizer have a negative impact on soil fertility, for example through acidification. However, an FAO meta-study on the effect of mineral fertilizers on soil organic matter in long-term trials – a key indicator of soil fertility – concludes that “apart from a few studies that found a decrease in soil organic matter after long-term fertilization, a disproportionately larger number of empirical studies concluded that fertilization led to an increase in soil organic matter accumulation”.

So what do these facts mean for the assessment of green synthetic nitrogen fertilizers in poor countries of the global South, especially for sub-Saharan Africa (SSA)?

First of all, the initial situation must be taken into account including the fact that the measurement of fertilizer consumption leaves a lot of room for interpretation, quite apart from statistical deficiencies. The average nitrogen fertilizer consumption in SSA is around 13 kg of nutrient per hectare and year (by comparison: North America 73 kg, China 170 kg), about twice as much (22 kg) if all the main nutrients (phosphate and potassium) are included and 50 percent more if the total weight of the fertilizers is counted. Only in a few African high- and middle-income countries such as Mauritius and in intensive vegetable cultivation are high levels of nitrogen similar to those in industrialized and emerging countries are applied. The country with the highest consumption is Zambia (approx. 80 kg per hectare and year of fertilizer in total), while in the DR Congo, for example – as large as the whole of Europe – only 2 kg is used. The majority of small-scale farmers on the continent use almost no mineral fertilizer.

The development of fertilizer consumption is influenced not only by economic development but also by the relative availability of land in many SSA countries. Whereas in earlier traditional agricultural systems there was a balance between cultivated and fallow land, these systems have long been unbalanced due to rapidly increasing rural and urban populations, higher production for markets and higher livestock densities. There is a massive consumption of soil nutrients that is not being compensated (soil nutrient mining). This net depletion accumulates over time and is probably the biggest problem for plant production, soil fertility and biodiversity in SSA – indirectly due to the pressure to constantly expand production areas into forests and savannahs.

Without fertilizers, these deficits cannot be compensated by ecological measures, or only very slowly, as many scientific studies have shown: Soils often do not have enough remaining nutrients, legumes can hardly produce enough nitrogen for an entire farm, and the huge amounts of farm fertilizer that would be required for purely organic farming are usually not available in sufficient quantities.

Increased nitrogen fertilization indicated

An increase in synthetic nitrogen fertilization is therefore indicated in most cases in SSA to stop and reverse the decline in soil fertility and the stagnation of yields. It is also recommended in most agronomic studies and scientifically-based national guidelines, including the Pan-African Fertilizer and Soil Health Action Plan of May 2025. Nitrogen fertilization is only likely to be an environmental and health concern in very few situations in SSA, at least at the moderate levels that are realistic in the foreseeable future.

If green synthetic nitrogen therefore has a smaller greenhouse gas footprint than conventional nitrogen, this is positive and is to be welcomed from an ecological point of view. However, nitrogen must not be used exclusively, a balanced supply of other plant nutrients is also required to achieve long-term and stable increases in productivity – and integrated soil fertility management is needed to balance nutrient supply and withdrawal, organic matter and soil acidity. Together with other objectives in crop production, such as erosion control, soil water retention, the prevention and control of pests and diseases as well as weed control, diversified crop rotation, agroforestry measures and gentle and erosion-reducing tillage are important principles. The latter enhance yields on their own, especially when compared to a situation without fertilization.

If only the ecological effects were taken into account, an assessment of the importance of green synthetic nitrogen fertilizer for SSA could end here – it is advantageous compared to normal synthetic nitrogen fertilizer, and it is not very harmful under the given circumstances. However, there is also the socio-economic dimension, which has a considerable bearing on the assessment. Even conventional and ecological recommendations by governmental and non-governmental organizations for improving nitrogen supply are not or only insufficiently adopted. This leads to factors that prevent many other innovations in smallholder agriculture in SSA in addition to fertilization, and which probably also play a role in the introduction of green synthetic nitrogen.

Socio-economic dimensions of site-specific nitrogen fertilization

The Factor of Complexity: The use of mineral fertilizers is complex and often requires a whole range of prerequisites and measures to be effective. This complexity of a multitude of different nitrogen fertilizers, together with the various admixtures of other nutrients, is often underestimated. Each plant species, and often different varieties, has different requirements depending on its stage of growth stage and reacts differently to different fertilizers. In addition, there are soils that do not make (some) fertilizers easily available to plants and require additional organic matter and possibly lime to prevent soil acidification. If the right combination is not used, effectiveness and thus the cost-benefit ratio of fertilizer use decreases.

In many countries, however, only a few fertilizers are approved or widely used, often controlled by the state, so that farmers do not have sufficiently differentiated combinations at their disposal. Fertilizers are also difficult to tell apart, there is a lot of fraud as well as ineffective/substandard products, which also dampens farmers' confidence in the recommendations. Differentiated fertilization also requires good information on the condition of the soil and sufficient knowledge to assess the situation, which is not the case for many smallholder farmers. Often, fertilizers are only effective with particular improved varieties. These combinations need to be well-known, the varieties need to be available and affordable for farmers – which is often not the case in SSA. However, it should also be mentioned here that the complexity of alternative agroecology is considerably higher.

The Factor of Dependency: A frequently voiced argument against the use of artificial fertilizers in general is the resulting dependency. Such claims about market dependencies are sometimes ideologically tinged or aimed at certain products and services in a highly one-sided manner (e.g. industrial inputs), while they are downplayed for alternative high-priced marketing, for example. Nevertheless, the issue of dependency is relevant. If established markets are disrupted, the security and existence of a business and the associated household can be jeopardized. The issue of resilience to disruptions in global markets has become more important following the coronavirus, Ukraine and energy price crises – and is exacerbated by increasing geopolitical risks.

How does this apply to new green synthetic nitrogen fertilizers?

New synthetic fertilizers do not reduce the challenges of dealing with the complexity using mineral fertilizers – the active ingredient is the same. At the same time, at the macro-economic level, the argument of the dependency in nitrogen fertilizer supply on a few producers was and is one of the main motives for an increased focus on local production, both organic and conventional. This is also taken up by the pan-African action plan for fertilizers and soil health. One motive for green synthetic nitrogen fertilizers is that the production of green hydrogen is being promoted in many African countries such as Namibia, Kenya and Mauritania – especially for the supply of clean energy to industrialized countries.

In order to avoid new dependencies of the producing countries, diversification towards local uses of green hydrogen can reduce risks. It also creates local added value and jobs. Green hydrogen, which is best converted into ammonia for transport across long distances without pipelines, can be used for local industrial purposes, with processing into green synthetic nitrogen fertilizer likely to be dominant in terms of volume. Dependency is thus reduced.

At the microeconomic level of the farm in SSA, a high dependence on external markets –vulnerable to fraud and politicized – represents a high risk, given the great importance of fertilizer for short-term yields and longer-term soil fertility. In contrast to many other markets, however, there are internal alternatives, at least for nitrogen, in the form of legumes and farm fertilizers, the expansion of which makes sense, but is not easy.

High costs and the risk of debt are other frequently cited arguments against green synthetic nitrogen fertilizers, as well as against purchased inputs in general. At the individual farm level, high fertilizer costs are an important issue for farmers. The use of technology packages, including the cost of improved varieties, is rarely affordable for smallholders. Indeed, smallholders need to be risk-averse, given the uncertainties in cultivation, markets and politics as well as the lack of capital, insurance and reserves. If farmers nevertheless are bold enough to buy fertilizer (and other products and services) on credit, they can fall into a debt trap. Even though there is usually a positive effect of increased fertilizer use on production and income.

Unclear information as well as the costs and risks of modernization packages contribute significantly to low fertilizer use in SSA. The result are subsidy programmes, which are now used to reduce the price of almost 50 percent of marketed fertilizer in many countries in the region. During the crises of recent years, poorer farmers in particular have reduced their use even further, while higher agricultural prices and subsidy policies have encouraged more investment by larger farmers and increased the amount of fertilizer overall.

The cost of fertilizer is already higher in small, poor countries in the global South than in large countries. This is due to smaller purchase quantities, as well as high transport and distribution costs, state-controlled purchasing and sales policies and the obstruction of competition on the markets by monopolists and nepotism. Politically driven subsidy policies in particular often contribute to these weaknesses in fertilizer markets. Most economists agree that the majority of subsidy programs are less effective than other government interventions such as investments in agricultural research, extension and local infrastructure, which, however, make a difference only in the long term.

For the eventual promotion of green synthetic nitrogen fertilizers, this means that they are likely to be significantly more expensive than conventional fertilizers, at least initially. Expensive green hydrogen, new technologies, small production plants and expensive logistics for small quantities are in competition with cheap natural gas and large established fertilizer distribution chains. Without state intervention, they are unlikely to be competitive initially. If countermeasures are taken by taxing fertilizer imports, the entire nitrogen market will become even more expensive and therefore less attractive for farmers. In addition, it is to be feared that local “green” producers will let quality slip under political protectionism.

Conclusion:

Nitrogen is a key driver for yields, stability and soil fertility in agriculture, but also for a wide range of ecological problems. In the long term, green synthetic nitrogen fertilizers can offer a great opportunity for more sustainable agriculture, not least in SSA. However, benefits are not automatic but depend on many factors that need to be considered.

The alternative, the possibility of organic accumulation of nitrogen on the many degraded sites in SSA, is also difficult at best and in any case lengthy. A combination of synthetic nitrogen, other external nutrients and agro-ecological measures is often the more sensible approach. This is where green synthetic nitrogen fertilizer could play a role. This is entirely compatible with agroecological principles, which, unlike organic farming, do not advocate the complete renunciation of external inputs, but rather their reduction. However, under the degraded conditions of many agricultural regions in SSA, an increase is usually necessary at first.

Considerations regarding the reduction of global nitrogen pollution also support a redistribution of nitrogen use from the global North, where it is used excessively, to the global South, where it has so far been underutilized and where demand for agricultural products will show the strongest increase.

However, it remains to be seen whether and where green synthetic nitrogen fertilizer can be produced competitively and become a real alternative for farmers. The cost of alternative energy and the way in which the products are brought to market will be decisive. Industrial policy of African states, which often favors industrial players at the expense of farmers, coupled with the urge of Western development policy to be more ecologically correct in the global South than at home, could lead to political conflict with affordable conventional, greenhouse-gas-intensive fertilizers on the one hand and the more expensive green alternative on the other.

However, advocating and supporting the use of synthetic nitrogen in poor countries should not be made dependent on the existence of green nitrogen. Rather, it should be questioned whether it is the correct priority and morally acceptable to point to greenhouse gas emissions in denying progress in production and income to smallholder farmers, who often emit far less than one ton of CO₂ equivalent and thus cause only a fraction of the emissions of people in other regions of the world. In this case, the right to development should take priority over a small reduction in greenhouse gases. These must be achieved first and foremost in industrialized and emerging countries.

Meanwhile, the time needed for developing this technology should be used to support sustainable smallholder agriculture as a whole, for example by developing cost-effective organo-mineral fertilizers that optimize the advantages of current fertilizers, by increasing fertilizer efficiency in the cultivation system, and by recycling nutrients on farms and from the end user back to the farms. Overall, investments in research, advice, infrastructure, markets and institutions are preferable to non-sustainable subsidies.