Fertilizer International 505 Nov-Dec 2021
30 November 2021
Better nitrogen use
NUTRIENT USE EFFICIENCY
Better nitrogen use
Improvements to nutrient use efficiency (NUE), particularly for nitrogen, can deliver dual environmental and economic benefits. We report on recent developments in nitrogen management and global progress on NUE.
With hindsight, 2015 is arguably the year when sustainability went mainstream, as it marked the UN’s adoption of sustainable development goals and the signing of the landmark Paris climate accord. The latter has now resulted in country-level plans being drawn up – the so-called nationally determined contributions (NDCs) – which in turn will depend on action by industry sectors and individual companies.
Fertilizer producers, being part of an energy-intensive industry, will be tasked with reducing their carbon emissions out to 2050. But the drive to improve nutrient management is equally, if not more, important. Fertilizers currently contribute 2.5 percent to global greenhouse gas (GHG) emissions. This total divides 60:40 between emissions generated by the application of fertilizers to land (1.5%) and those emitted during fertilizer production (1%).
The need for sustainable nitrogen management has certainly risen up the policy agenda, culminating with the United Nations Environmental Assembly’s March 2019 resolution. This noted that:
“Global, economy-wide nitrogen use is extremely inefficient with over 80% of anthropogenic reactive nitrogen lost to the environment, which leads to water, soil and air pollution that threatens human health, wellbeing and ecosystem services and contributes to climate change, due to increases in greenhouse gas emissions, and stratospheric ozone depletion.”
Nutrient losses
Achieving global food security, today and in the future, cannot be achieved without fertilizers. With the global population due to reach 10 billion people by 2050, world agriculture needs to increase its productivity by 60 percent, from a 2005 baseline, if it is to meet extra demand for food. And fertilizers provide a dramatic and immediate improvement in land productivity. Within a single growing season, assuming water supply is also sufficient, fertilizers can double or triple farm productivity: for every single kg of nutrients applied, farmers obtain 5-30 kg of additional produce.
ICL SPECIALTY FERTILIZERS
ICL Ronald Clemens, marketing & portfolio manager CRFs
Is sustainability becoming more important?
For ICL, sustainability is a core factor in our company’s mission. As a leading global specialty minerals company, we are creating impactful solutions for humanity’s sustainability challenges – in the global food, agriculture, and industrial markets. We adhere to the highest environmental standards and utilise the best available technologies in order to develop sustainable approaches.
Does the industry need to do more on nutrient use efficiency and stemming nutrient losses?
We consider improvement in nutrient use efficiency as very important. It is clear that higher fertilizer efficiency is crucial to reducing environmental pollution, but also to make sure that mined nutrients from our mother earth are used in the most efficient way. In our innovation programmes, sustainability and nutrient use efficiency are core values.
What role will new products, such as controlled release fertilizers (CRFs) and enhanced efficiency fertilizers (EEFs), play in delivering improvements in nutrient use efficiency?
We see CRFs and EEFs as important technologies for improving the efficiency of nutrients. This first of all relates to nitrogen, but also to phosphorus and potassium. It is a way to improve yields – and so reduce the land used to produce similar quantities of food – or, alternatively, reduce fertilizer use and maintain existing yields. Together with the right fertilizer application methods, there is still a lot to win in nutrient use efficiency.
Environmental protection is often thought to come with a price tag attached. Can the higher nutrient use efficiency delivered by CRFs and EEFs help combine environmental improvements with economic dividends for growers?
This is very important. Economic benefits for the farmer make the entrance of CRFs and EEFs easier. Improved nutrient use efficiency means also economic advantages for the farmer by better yields or lower inputs. The lower inputs can also result in less applications and reduced labour costs. In a lot of cases this is already proven. That is why our agronomy department puts a lot of effort into field trials to show the economic benefits for the farmer in many agricultural crops.
Yet the statistics on average nutrient use efficiency – the proportion of nutrients actually used by crops in the first year after application – are stark. For fertilizers applied to major cereal crops, nitrogen efficiency is around 40-65 percent, potassium efficiency in the region of 30-50 percent and phosphorus efficiency just 15-25 percent1 .
The above figures are for plots managed by agronomic researchers. Values for nitrogen use efficiency on fields managed by farmers are even less encouraging. Up to 70-80 percent of applied N can be lost in rain-fed conditions and 60-70 percent lost in irrigated fields, when fertilizers are improperly managed (Fertilizer International 474, p32).
Nitrogen losses are especially problematic due to their scale. Globally, agricultural soils receive an average total of 73 kgN per hectare per year, according to a recently-published study2 . Fertilizers and manures are responsible for 61 percent of this supply, the remainder coming from natural nitrogen fixation (29%) and atmospheric deposition (10%). Yet, on average, only half of the nitrogen applied to fields is taken up by crops.
Nutrient use efficiency also varies dramatically regionally, being much lower in Eastern China (33%), for example, than in either the United States (65%) or Western Europe (61%). Losses to the atmosphere from ammonia volatilisation are also a major issue for nitrogen fertilizers, ranging from 17 percent in Europe and the US to 22 percent in China2 .
Inevitably, there are a range of undesirable environmental impacts associated with the inappropriate and excessive application of fertilizers – particularly nitrogen fertilizers such as urea. These include the release of nitrates into water bodies and emissions of ammonia and nitrous oxides into the atmosphere. The latter contributes to agricultural GHG emissions, while the former, alongside phosphorus pollution, depletes the oxygen content of rivers, lakes and the ocean. This ultimately results in the large-scale aquatic ‘dead zones’ that appear seasonally in the Gulf of Mexico and Baltic Sea due to run-off from major rivers.
Understanding nutrient use efficiency
Nitrogen use efficiency measures the ratio between:
- Nitrogen output: the amount of N removed from the field with the harvested product; and
- Nitrogen input: the sum of the amounts of N applied to cropland from mineral fertilizers, livestock manure and via biological fixation (by rice, sugarcane and legumes such as soybean).
Low output/input ratios (below 50%) are associated with nutrient losses to the environment, while high ratios (above 100%) are indicative of soil nutrient mining, a process that eventually reduces soil fertility. Both these scenarios are clearly unsustainable. The optimum nitrogen output/input ratio is generally close to 60-90%, depending on the farming system and the crops cultivated, as values in this range promote high crop productivity3 (Figure 1).
NUE trends vary widely between regions and countries due to difference in:
- Soils, crops and climate
- Fertilizer management practices
- The access of farmers to technology and knowledge
- Policy priorities.
Fruits and vegetables, for example, typically have a lower NUE due to their high nitrogen input requirements, whereas legumes such as leguminous soybean have a high NUE due to their ability to capture nitrogen and fix this biologically. Likewise, sandy soils have a lower NUE potential than loam soils as they are less able to retain nitrates3 .
STAMICARBON
Pejman Djavdan, CEO
Is sustainability becoming ever more important?
Stamicarbon, the innovation and licensing company of Maire Tecnimont Group, considers sustainability the key to the future of the fertilizer industry. Mineral fertilizers play a decisive role in feeding the world – but are faced by several challenges related to the fertilizer production process and application. Stamicarbon has accepted these challenges and is therefore focussing its innovation efforts on sustainable fertilizer technologies: specifically on production of fertilizers based on renewable energy, technologies for speciality fertilizers that are more efficient and effective, and digital transformation of current urea plants.
Does the industry need to do more on nutrient use efficiency and stemming nutrient losses?
Yes, there is a need for the fertilizer industry to respond to these environmental concerns and Stamicarbon, as part of its Vision 2030 strategy, is pro-actively developing new and improved fertilizer production technologies – with the aim of decreasing emissions and energy consumption, and significantly increasing the nutrient use efficiency of fertilizers.
What role will new products, such as controlled release fertilizers (CRFs) and enhanced efficiency fertilizers (EEFs), play in delivering improvements in nutrient use efficiency?
Nutrient/nitrogen use efficiency can be significantly increased by offering a crop the right nutrients at the right time. Offering the right nutrients can be achieved by compounding different nutrients in the right ratio into one fertilizer granule. Releasing these nutrients over time can be achieved, either by inhibiting the biological transformations in the soil, or by controlling the release of the nutrients via our coating technology. Stamicarbon has several technologies available for adding micronutrients to urea and improving urea efficiency.
Environmental protection is often thought to come with a price tag attached. Can the higher nutrient use efficiency delivered by CRFs and EEFs help combine environmental improvements with economic dividends for growers?
Absolutely. It is possible to combine environmental improvements with economic advantages for growers – and it is important to make that economic case. But the actual economic advantages depend on the geographic location, crop type and local soil conditions. In regions with an overapplication of nitrogen but with an acceptable crop yield (e.g., China), savings on fertilizer usage may prevail. In regions with nutrient depletion and a low crop yield (e.g., Africa), an increase in the crop yield may take precedent, and in regions with an improved nutrient use efficiency and a high crop yield (e.g. USA or EU), the environmental improvements might be the decisive factor.
Nutrient stewardship
In the early 2000s, the global fertilizer industry – notably the International Fertilizer Association (IFA), The Fertilizer Institute (TFI), Fertilizers Canada and the now defunct International Plant Nutrition Institute (IPNI) – developed the concept of ‘4Rs’ nutrient stewardship. This specifically linked the management of plant nutrients to sustainability objectives through a simple yet universal message. This urged farmers to apply the right source of nutrients, at the right rate, at the right time, and in the right place – hence 4Rs.
By using the 4Rs to manage nutrients more efficiently, farmers can sequester more carbon in their soils and reduce:
- Agricultural land expansion
- Denitrification and the resulting nitrous oxide emissions
- The N and P flows from land that cause eutrophication
- Nitrate accumulation in groundwater. In practical terms, nutrient stewardship can be delivered through fertilizer best management practices (BMPs). These allow fertilizers to fulfil their primary function – that is providing crops with a consistent and easily available supply of nutrients – and perform this efficiently by minimising the risks of losses and the negative effects of fertilizer overuse, underuse or misuse.
As well as promoting precision agriculture and associated technologies such as fertigation, fertilizer BMPs encompass the following approaches:
- Balanced fertilization: ensuring a proper and balanced supply of macronutrients and micronutrients to crops throughout the growing season.
- Integrated plant nutrient management (IPNM): supplementing the supply of available on-farm organic fertilizers to crops with mineral fertilizers.
- Site- and crop-specific nutrient management: the balanced use of crop nutrients taking account of soils, crops and climate. This allows growers to match nutrient supply with crop requirements, and maintain soil fertility and optimise yields, while minimising losses to the environment.
In 2016, as part of their outreach work with farmers globally, IFA, the World Farmers’ Organization (WFO) and the Global Alliance for Climate Smart Agriculture (GACSA) published the Nutrient Management Handbook. This accessible 35-page manual provides farmers with useful and straightforward practical information on how to improve nutrient use efficiency without detriment to crop yields, soil fertility and water productivity.
The Scientific Panel on Responsible Plant Nutrition
Following the outcome of its strategic review, IFA established a Scientific Panel on Responsible Plant Nutrition at the end of 2019. This was set up to strengthen and improve nutrient stewardship efforts internationally by answering a growing need for scientific research and expertise. The Panel is composed of eminent plant nutrition experts from leading research organisations around the world. Its mission is to advance sustainable plant nutrition and address the key challenges facing agricultural systems globally – especially how to improve agricultural productivity sustainably, while maintaining soil health and minimising nutrient losses to the environment.
PURSELL AGRI-TECH
Nick Adamchak, CEO & president
Is sustainability becoming more important?
The progression to a more sustainable future in agriculture continues to gain momentum. Perhaps the best barometer of that is the amount of financial and scientific investment that is flowing into the crop nutrition space. Whether it is biological products, nitrogen fixation, controlled-release fertilizer or repurposing food waste, innovation in crop nutrition has never been higher. The fertilizer industry – The Fertilizer Institute specifically – is doing their part under the framework of the 4Rs programme.
Does the industry need to do more on nutrient use efficiency and stemming nutrient losses?
The short answer is yes. It is imperative that the industry address both greenhouse gas emissions as well as global water quality challenges. The recent EPA/USDA Challenge (Fertilizer International 503, p20) highlights the growing concern around extreme nutrient losses both in water and GHG emissions. Regulation could occur if the industry does not begin to show improvements in reducing nutrient losses, especially N and P. Improving nutrient use efficiency and reducing impacts to air and water quality are the focus of our ongoing efforts.
What role will new products, such as controlled release fertilizers (CRFs) and enhanced efficiency fertilizers (EEFs), play in delivering improvements in nutrient use efficiency?
In precisely calibrating nutrient release to the growth requirements of crops, controlled-release fertilizers are the most efficient nutrient delivery system available. CRFs deliver additional efficiencies by also eliminating nutrient leaching and volatilisation. Pursell’s unique ability to also incorporate micronutrients, biologicals and humates inside the coating adds to a farmer’s ability to improve plant health and maximize yields. As the relative cost and availability of CRFs/EEFs come down, adoption will be much higher.
Environmental protection is often thought to come with a price tag attached. Can the higher nutrient use efficiency delivered by CRFs and EEFs help combine environmental improvements with economic dividends for growers?
Farmers and Certified Crop Advisors (CCAs) must understand the financial and environmental benefits of using more efficient fertilizer technologies. Higher NUE results in higher yields which offer a financial payback. Additionally, more efficient fertilizers support soil health and regenerative agriculture which have further paybacks to farmers.
Progress on nutrient use efficiency
In May 2020, IFA reported on progress in improving nutrient use efficiency (NUE) worldwide3 This painted a generally improving picture. At the global level, NUE has actually been steadily rising for three consecutive decades now, reversing the falling trend that preceded this up until the end of the 1980s. This rising trend has been driven by the continuous improvements in NUE achieved by developed countries, says IFA, as well as by China more recently. Global NUE was estimated at 59 percent in 2017.
A general trajectory in NUE is observed in many countries (Figure 2). NUE typically falls and then rises as it moves through four main stages:
1. Nutrient mining. Before countries adopt nitrogen fertilizers, their NUE is very high, often well over 100%, as they do not have enough N from manure or through biological nitrogen fixation to offset N removal through harvests.
2. Early development. As nitrogen fertilizers become available (and/or are subsidised to stimulate demand), fertilizer consumption generally increases much faster than removal by crops. As a result, NUE drops quickly.
3. Turning point. An inflection or turning point is eventually reached. This generally happens once medium to high crop yields are attained, and once farmers, policymakers, scientists and others begin to prioritise the improvement of NUE to limit nitrogen losses to the environment.
4. Sustainable intensification. Finally, after the turning point is reached, nitrogen surpluses stabilise or decrease owing to access to improved knowledge, inputs and technologies. Such improvements protect crop productivity while reducing nitrogen losses.
At a given moment in time, countries occupy different points on the U-shaped NUE curve shown in Figure 2. This reflects the maturity of their agricultural sector and their relative crop productivities. IFA suggests that, for those countries still at the start of the NUE trajectory (particularly in sub-Saharan Africa), there is potential to ‘tunnel through’ this U-shaped curve and avoid the unsustainably low NUE turning point described above. Building on the experiences of more mature agricultural economies, this could be achieved by taking environmental considerations into account from the outset – and consequently implementing policies that encourage both greater and more efficient use of nitrogen fertilizers.
IFA examined how NUE has changed in six countries – Brazil, the US, Denmark, China, India and Nigeria – from the 1960s to the 2010s. Its report concluded that:
- Too high and too low nitrogen output/ input levels are both equally unsustainable
- Countries with a large share of their area planted to legume crops have a higher NUE, while countries with a high proportion of less nitrogen efficient crops (e.g., fruits and vegetables) have a lower NUE
- Countries where farmers have adopted fertilizer BMPs, new technologies (e.g., precision farming, drip irrigation etc.) and improved crop varieties have a higher NUE
- Countries where fertilizers are heavily subsidised (e.g., India) have a lower NUE
- Countries with high livestock production density have a lower NUE, as manures make up a higher percentage of total nitrogen input
- The integrated use of mineral and organic fertilizers is most promising for sequestering soil carbon in agricultural soils.
The report sensibly recommends adopting fertilizer BMPs that are tailored to site-and crop-specific conditions. This should enhance NUE and reduce environmental nutrient losses while increasing yields.
IFA also concludes that combining the 4Rs message with new products and technologies can deliver further improvements in NUE. Precision agriculture, for example, by simultaneously increasing productivity and reducing GHG gas emissions, is capable of steering agriculture towards a more sustainable ‘input-optimised’ model. Examples include:
- Mobile/digital apps that allow farmers to send pictures of their crops and receive tailored fertilizer recommendations
- Hand-held sensors that can measure the nitrogen status of crops
- Sensors that can assess the water requirement of plants by measuring pressure on leaves.
Nevertheless, reaching out to the world’s 500 million farmers – especially smallholders – to help them implement fertilizer BMPs remains the major challenge. By improving the access of farmers to knowledge and inputs, policymakers and fertilizer producers have a role to play too. Subsidy reforms that promote the efficient and balanced use of plant nutrients will also undoubtedly be necessary.
Economic and environmental rewards
The EU’s recently-published Farm to Fork Strategy sets Europe the goal of reducing its nutrient losses by 50 percent by 2030. In its response to the Strategy, Norway’s Yara International highlighted both the importance of nutrient use efficiency and the role of technology:
“Farmers can reduce nutrient losses by improving nutrient use efficiency, as these are two sides of the same coin. With our extensive agronomic knowledge and portfolio of solutions, Yara can help farmers increase nutrient use efficiency.
“Farmers can do this by using precision and digital farming tools and by adopting optimal nutrient management practices – applying the right fertilizer at the right time, in the right dose and at the right place.”
Indeed, by adopting best practices and solutions that already exist today, Yara says that European farmers could:
- Improve nutrient use efficiency by 20 percent
- Increase yields and income by 5-7 percent l Reduce the carbon footprint of mineral fertilizers by up to 20 percent.
This illustrates how improving NUE can be as good for the bottom line as it is for the environment.
References
