Fertilisers: Feeding agriculture’s growing needs


World fertiliser production is expected to soar to keep up with rising food and biofuel output, but this also triggers environmental problems as fertiliser sucks up energy and trigger water and soil pollution.

Plant growth is only possible with sufficient nutrient and water, which acts as a carrier.

Fertilisers replace the natural nutrients that are removed from fields with each harvest. They help to bridge the gap between those required for optimal crop growth and those present in the soil.

Fertilisers typically provide six macronutrients which are essential for plant growth: nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and sulphur (S). They also feature seven micronutrients: boron (B), chlorine (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo) and zinc (Zn).

Fertilisers are broadly divided into naturally-occurring organic fertilisers composed of enriched organic plant or animal matter, such as manure and compost, and inorganic fertilisers composed of synthetic chemicals and minerals.

Three primary nutrients – nitrogen, phosphorous and potassium – are used as synthetic chemical fertilisers in industrial agriculture. The building block of nitrogen fertilisers is ammonia, which results from combining nitrogen from the air with natural gas, while phosphorus and potassium are extracted from mined ores.

Mined inorganic fertilisers have been used for many centuries, whereas chemically synthesised inorganic fertilisers were only widely developed during the industrial revolution.

According to some studies, 40 to 60% of global crop yields are attributable to commercial fertiliser use.

The EU's current fertilisers regulation, itself a recast of 18 earlier directives, covers only a proportion of the mineral fertilisers that are sold in the bloc. The law does not cover organic fertilisers. Meanwhile, ever larger quantities of fertilisers are now being produced from organic waste streams.

A recently published ex-post evaluation of the current regulation confirmed the need to extend the scope of the legislation and called for a harmonised EU system to cover all fertilisers – organic and mineral fertilisers, growing media, soil improvers and possibly bio-stimulants.

Growing demand

The fertiliser industry essentially supplies three major plant nutrients – nitrogen, phosphorus and potassium. The several other micro-nutrients (see 'Summary') can be incorporated into these key fertilisers or supplied as speciality products.

Growing demand

The fertiliser industry essentially supplies three major plant nutrients – nitrogen, phosphorus and potassium. The several other micro-nutrients (see 'Summary') can be incorporated into these key fertilisers or supplied as speciality products.

The main nutrient used in agriculture is nitrogen, of which total consumption across the EU's 27 member states stood at 11.2 million tons in 2008, compared to 3.1 million tons of phosphorus and 3.6 million tons of potassium in the same year.

Global demand for fertilisers will grow at a rate of 2.6% per year from 2010 to 2014, estimates the UN Food and Agriculture Organisation.

Europe's share of global fertiliser consumption stands at 13%. For nitrogen fertiliser it is 13.9%, for phosphate 9.3% and potash 15.7%, according to the FAO. Their consumption is expected to rise by 1.9, 3.1 and 4% respectively per year between 2010 and 2014.

The European Environment Agency predicts that mineral fertiliser use will increase considerably in the bloc's new member states in the decades to come, potentially increasing associated environmental pressures.

The agency predicts that the use of nitrogen mineral fertilisers will increase by about 35%, while phosphate and potassium use will rise by 52% and 41% respectively. This contrasts sharply with the situation in the old EU 15, where the use of mineral fertilisers is expected to stay fairly stable until 2020.

Environmental, health hazards

Despite their success in boosting crop production, using fertilisers in agriculture increases environmental risk, particularly with respect to water and soil pollution. Fertilisers can interfere with the natural balance of soil's microflora and cause acidification, for example.

Nitrogen and phosphorus nutrient run-off from agricultural land reaching lakes, rivers and the sea presents another major problem. An excess of these nutrients in aquatic systems causes eutrophication – the depletion of oxygen in the water – which in turn promotes excessive plant growth like algal blooms, especially in coastal areas.

1991's EU Nitrates Directive aims to protect water quality across Europe by preventing nitrates from agricultural sources polluting ground and surface water and by promoting the use of good farming practices.

High levels of nitrate and nitrite in drinking water – through their accumulation in groundwater – pose a threat to human health as they can reduce the ability of human blood to carry oxygen. Infants are particularly susceptible to nitrate poisoning – a phenomenon known as 'blue baby syndrome'.

According to the EU executive, the current provisions of the fertilisers regulation do not always fully address related environmental concerns, and "a revision is needed to introduce more stringent environmental safety requirements".

The EU is currently reviewing the regulation and a study on the related economic, environmental and social impacts is expected to be finalised by December. 

proposal for a regulation relating to fertilisers, which would repeal the current regulation, is expected to be tabled late next year.

The Commission has already pledged to consider including maximum limits for the presence of heavy metals in mineral fertilisers in the revised law. The current regulation only sets a limit for copper. But steel industry waste, for example, which is recycled for use as fertiliser due to its high level of zinc, can also include toxic substances like mercury, lead and arsenic.

In parallel, the EU executive is leading discussions on draft legislation to regulate the amount of cadmium in fertilisers. Cadmium is a heavy metal naturally present in phosphate rocks mined for fertiliser. Using phosphate fertiliser can thus lead to the accumulation of cadmium in agricultural soils.

Towards more sustainable practices

The EU's future farm policy after 2013 is set to place an increasing focus on sustainable agricultural practices and could well include measures to support and disseminate best practices for fertiliser handling to reduce environmental pressures.

Good practices in nutrient use include integrated soil fertility management, which combines the use of fertilisers to increase yields with seeking to improve the quality of depleted soils.

In parallel, precision farming is a technique that allows farmers to better allocate inputs – such as fertilisers – to specific cropland areas based on soil type, fertility levels and other characteristics of a site to optimise resource use and reduce negative impacts on the environment.

One precision farming technique is so-called 'fertigation', which describes the application of fertilisers through an irrigation system. Soil fertility or plant tissue analyses are used to determine which nutrients should be used, after which the plants are 'spoon fed' throughout the growing season in order to account for fruit, flower, and root development. The practice can thus reduce the need for fertiliser and consequently its escape into the water table.

While fertigation can be adapted to all types of crops, the high infrastructure cost of the technique means it is usually only carried out for high-value crops, such as vegetables and fruit trees, rather than broad-acre or arable crops.

Energy and climate change

The production of fertiliser is energy intensive and is responsible for around 1.2% of the world's total greenhouse gas (GHG) emissions.

The nitrogen fertiliser industry is the EU's biggest single industrial consumer of natural gas, which it uses as a primary raw material for production. And like with other fossil fuels, burning natural gas emits major greenhouse gases like carbon dioxide (CO2).

In addition, the application of fertilisers to fields gives rise to emissions of nitrous oxide (N2O) through a microbial process called 'denitrification', which returns nitrogen to the atmosphere (NO2 emissions also occur naturally from the soil's micro-organism activity). N2O has 310 times the warming ability of CO2, the most common greenhouse gas.

Heavy use of synthetic nitrogen fertilisers, particularly where soil conditions are favourable to denitrification, can lead to large amounts of N2O being produced and emitted into the atmosphere.

Relatively straightforward practices can help limit those emissions. So-called 'precision farming' techniques can optimise inputs to reduce NO2 emissions. For example, fertilisers can be targeted at the areas that most need them, with input spread over time to optimise use and avoid waste.

Finite resources: Focus on recycling

The main three plant nutrients – nitrogen, phosphorus and potassium – are produced in ways which cannot be continued indefinitely as the resources used in their production are non-renewable.

Potassium and phosphorus come from mines and, as such, these mineral resources are limited. Natural gas, meanwhile, is a finite non-renewable fossil fuel. 

The industry therefore sees supplies of those minerals as an essential part of the EU's raw materials strategy, which emphasises the importance of local mining, trade and recycling.

However, options are limited. On the mining side, there is only one phosphate mine, north of Kupio in Finland, which is the only apatite mine in Western Europe. Meanwhile, others phosphorus products are based on imported raw materials from outside Europe.

The industry is therefore calling for recycling policies to reduce the EU's dependency on imports. In fact, it says secondary sources of phosphorus remain largely untapped – in sewage, animal waste, food and other industry wastes.

Sustainability of the industry

As the EU gears up its efforts to fight climate change and sets carbon reduction targets for industry, European fertiliser companies fear that they may face targets that are "too tough".

Indeed, tough times lie ahead for fertiliser production in Europe, due to the industry's inclusion in the European Emissions Trading Scheme from 2013 (ETS III), which will impose carbon emission caps on the sector for the first time.

Inclusion in ETS III will inevitably put pressure on the profit margins of EU fertiliser producers, with some fearful of competition from foreign firms that do not work under such constraints. The industry argues that the scheme will force European fertiliser manufacturers to pay considerable carbon charges, while neighbouring competitors will not. Such trading disadvantages will lead to production simply moving outside the EU (so-called 'carbon leakage') to less stringent regulatory environments, it warns.

A European Commission evaluation identified the manufacture of fertiliser and nitrogen compounds alongside the mining of chemical and fertiliser minerals among the industries "at risk" of carbon leakage. Consequently, it has offered to distribute carbon allocations for free to firms operating in these sectors during the ETS trading period 2013-2020.

But the free pollution permits will only be handed to the cleanest producers, with ambitious benchmarks defined according to the 10% best-performing plants in the sector. According to the industry, free emission rights would thus only apply to the 5% most efficient and modern plants, whereas the remaining 95% will have to pay for individual carbon emission rights.

This will only increase Europe's dependence on fertilisers imported from other regions, producers say. And because Europeans currently run the cleanest production plants in the world, moving nitrogen production outside the EU would increase global carbon emissions, they argue.

More specifically, the industry is outraged that installations using a technology called NSCR (non-selective catalytic reduction) have been taken into consideration by the Commission when defining which plants will receive free emissions permits. European fertiliser producers argue that NSCR is in fact not a 'Best Available Technology' as it emits considerable amounts of CH4, CO2 and NH3. Fertilisers Europe, a trade group, is strongly calling for such plants be excluded from the benchmarking exercise.

Europe's fertiliser industry is also worried about access to natural gas at competitive prices, which can represent up to 50-70% of the total production costs of nitrogenous fertilisers. Fertilisers Europe says the increase in the price of natural gas since 2000 has led to a significant rise in the price of fertilisers across the EU.

EU farmers' body Copa-Cogeca has warned that soaring fertiliser prices are a major threat to farmers' ability to produce enough food to meet growing global demand. 

In the upcoming review of the EU's fertilisers regulation, the European Commission is seeking to promote a stronger single market for all types of fertiliser. The aim is to achieve full harmonisation of legislation across all 27 EU member states, including on environmental requirements, which are often a cause for concern among industry players.

The EU executive notes that in recent years, concerns "have moved from information to farmers about the minimum nutrient content of fertilisers to environmental concerns (e.g. presence of heavy metals in mineral fertilisers)". It argues that "the provisions of the current fertilisers legislation are quite limited in this respect and further revision is needed to introduce more stringent environmental safety requirements".

While agriculture as a sector is not part of the emissions trading scheme (ETS), the Commission hopes to steer farming onto a greener path by extending the cap-and-trade scheme to the energy-intensive manufacturing sector as of 2013. This would include the manufacture of fertilisers and nitrogen compounds as well as mining of fertiliser minerals.

The EU's future farm policy for the post-2013 era is also set to place an increased focus on protecting biodiversity, promoting sustainable farming and achieving CO2 emission reduction goals. Under proposals being considered in Brussels, 30% of direct payments would be made conditional on "green" measures, such as improving the efficient use of fertilisers in food production.

The European Environment Agency (EEA) notes that using fertilisers brings with it environmental hazards, such as water and soil pollution. The agency says fertilisers also have negative effects on other environmental components, interfering with the natural balance of soil microflora, while high levels of nitrate and nitrite in drinking water are a threat to human health.

But the agency adds that "the actual environmental effects will depend on pollution abatement methods, soil and plant types, and meteorological conditions".

A five-year research project by the European Science Foundation recently concluded with the publication of a European Nitrogen Assessment (ENA) report. The study sounded the alarm about the role of agriculture in generating reactive nitrogen (though not only through fertiliser use) and the subsequent damage caused to the environment and to public health. It estimated the cost of the damage to Europe at €70-320 billion per year, in addition to cutting European life expectancy by six months.

At the same time, however, the assessment notes that the economic benefits of nitrogen are "very substantial" and that almost half of global food can be produced thanks to it. It also argues that without fertiliser, cereal yields in Europe would only amount to half or two thirds of those with optimal fertiliser application. In addition, the authors note that nitrogen is essential not only to meet the challenges of food security, but also for energy security "with the increasing importance of biofuels".

According to the assessment, "legislative drivers to reduce Nr [reactive nitrogen] use, including mineral fertiliser, must take account of the nitrogen benefits in agricultural production needed to maintain food and energy security, given the limited options to increase arable land area".

The authors of the assessment believe that increasing fertiliser prices and climate change will create new incentives to increase nitrogen use efficiency, for example through "N-conserving field practices such as catch crops, reduced soil tillage, better estimation of crop N requirements and improved timing and placement of N inputs".

The UK Department for Environment, Food and Rural Affairs (Defra) notes that "good nutrient management aims to maximise the on-farm benefit from using fertilisers whilst also minimising the risk of nutrient pollution and costly over-application of fertiliser".

Meanwhile, the standard of nutrient management must improve to help contribute to sustainable food production, it added, highlighting the need to ensure carefully managed and optimised "on-time" application of all nutrients, including mineral fertilisers and organic materials such as slurries and manures, to optimise production benefits.

A recent report commissioned by the French Ministry of Agriculture recommends developing a plan called 'Ecofertilisation 2020', which would decrease the agricultural sector's dependence on mineral fertilisers. The development of a specific fertiliser programme would acknowledge the essential role played by fertilisers in a competitive French agricultural sector, while also acknowledging that their environmental impacts need to be reduced.

The French 'Ecofertilisation 2020' plan could be focused around further optimising the use of fertilisers, encouraging the emergence and use of "environmental" fertilisers, such as organic by-products, while fostering an ambitious industrial policy. Specific actions might include strengthening the country's nitrate policy, the establishment of a carbon 'Bonus-Malus' mechanism for all mineral and organic fertilisers, and facilitating the transport of organic by-products of animal origin from regions growing livestock to areas of crop culture.

Fertilisers Europe, the European fertiliser manufacturers' association, stresses that the issues facing the nitrogen fertiliser industry in Europe "need to be seen within the global perspective for agriculture". In order to provide enough food for a growing world population, agricultural output around the world must increase by some 70%, for example by increasing farmland yields "by using modern and proven farming methods".

The industry group also seeks to highlight the "net contribution" made by the sector to the global carbon footprint, underlining that deforestation for expanding farmland would have a far greater impact on GHG emissions than using fertilisers to increase yields from existing land.

Fertilisers Europe calls for the upcoming reform of the Common Agricultural Policy (CAP) to promote good fertilisation practices, with fertiliser management programmes using precision farming and sensor technology. It also backs "the proper use of the most efficient fertilisers, at the right application rate, at the right place and time" to reduce their carbon footprint and improve nitrogen-use efficiency.

The International Fertiliser Industry Association (IFA) recognises that the sector contributes directly and indirectly to GHG emissions, particularly of carbon dioxide (CO2) and nitrous oxide (N2O), through the production, distribution and use of fertilisers.

But it stresses that fertilisers are an essential tool to limit additional emissions related to greater agricultural production. "Fertilisers help increase agricultural productivity, reducing GHG emissions per unit of agricultural input. Enhanced yields are particularly important in helping to prevent deforestation, which is the most important contribution of GHGs related to agriculture," it noted.

Therefore, the association is promoting "a life-cycle approach" encompassing fertiliser production, transport and use to reduce the industry's impact on climate change.

Yara, the world's largest producer of nitrogen-based fertilisers, acknowledges that inappropriate use of mineral fertilisers may cause serious pollution. The company says it has invested heavily "to ensure accurate matching of nutrient supply and crop need to meet good agricultural practice, reducing the detrimental effects on water quality while allowing economic agriculture to continue".

Regarding GHG emissions, Yara says that only a full life-cycle analysis of fertilisers can accurately determine their climate footprint, including transportation and storage, as well as during application and crop growth.

Acknowledging the industry's role in emitting GHGs, Yara stresses that fertilisers also bring climate benefits by stimulating crop growth and related CO2 uptake. Fertilisers also reduce the necessity to cultivate new land, thus avoiding GHG emissions from land-use change, it argues.

The environmental NGO Greenpeace, citing scientific studies, has highlighted a series of measures that should be taken to improve nitrogen-use efficiency. These include adjusting application rates based on precise estimations of crop needs (precision farming), using slower controlled-release fertiliser forms or nitrification inhibitors, and applying N when least susceptible to loss, often just prior to plant uptake (improved timing). Others include placing the N more precisely into the soil to make it more accessible for crops' roots and avoiding applications in excess of immediate plant requirements.

Research published in a special issue of Waste Management & Research (Enzo Favino, Dominic Hogg) suggests that soil fertilised with organic materials, such as compost, could increase the amount of carbon stored in soil and potentially help slow down greenhouse-gas emissions. Organic fertilisers could reverse the decline in soil organic matter by contributing to the build-up of the stable organic part of soils to retain more carbon.

  • Nov. 2010: Final report on ex-post evaluation of existing Fertilisers Regulation.
  • April 2011: European Nitrogen Assessment.
  • 19 Oct. 2011: Food fertilisers and natural resources conference.
  • Nov. 2011: Final report expected on options to fully harmonise EU legislation on fertilisers, including technical feasibility and environmental, social and economic impacts.
  • 2012: Impact assessment of options to harmonise EU fertiliser market.
  • Dec. 2012Proposal for regulation relating to fertilisers, to repeal current regulation.

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