Fertilizer International 505 Nov-Dec 2021
30 November 2021
Enhanced efficiency fertilizers for sustainable agriculture
FERTILIZER TECHNOLOGY
Enhanced efficiency fertilizers for sustainable agriculture
Conventional fertilizers can be transformed into enhanced efficiency fertilizers (EEFs) using coating agents and inhibitors. Greater use of EEFs, by preventing nutrient losses and avoiding excess nutrient supply, can help global agriculture become more sustainable, as Urvi Mathur of Neelam Aqua explains.
Rising agricultural emissions and excessive fertilizer use
In 2018, global emissions from agriculture rose to 9.3 billion tonnes of CO2 equivalent, a 14 percent increase this century. Crop production and livestock are the main emission sources contributing 5.3 billion tonnes (57%) of CO2 to this total. Three major economies – India, China and Brazil – are the top three agricultural emitters globally, a sign of agricultural intensification and the rising use of fertilizers and agrochemicals in recent decades. Emissions from African agriculture are also on an upward trend currently.
Agricultural land – which accounts for nearly 40 percent of global land area – notably generates large volumes of nitrous oxide, largely due to livestock manures and the soil application of nitrogen fertilizers. This is concerning as nitrous oxide makes up around one-third of global agricultural emissions (CO2 equivalent) and has 300 times more global warming potential than carbon dioxide. It is also a major ozone-depleting chemical.
The increased use of nitrogen fertilizers, especially urea, stems from the need to raise yields and guarantee food security (a vital requirement in most developing countries) at a time when the population is rising yet the available arable land area is falling. While balanced fertilization is a necessity for delivering good crop yields, excessive fertilizer use has the potential to severely damage the environment.
The excessive application of mineral fertilizers, beyond crop requirements, is completely counterproductive too, as this has little to no effect on yields. Indeed, on average, around 50 percent of the nitrogen fertilizers applied to soils are never consumed by the crops. Instead, they are lost to the environment – as a result of volatilisation, nitrification and denitrification processes (see box).
Nitrogen losses: a threefold problem
Nitrogen is lost to the environment via three main processes: volatilisation, nitrification and denitrification.
Volatilisation
During volatilisation, urea is converted into ammonia via the hydrolysis reaction with the urease enzyme. Nitrogen is then lost to the atmosphere as gaseous ammonia if the fertilizer is not incorporated into the soil. As well as being climate-sensitive, ammonia emissions can also increase air pollution, be an air quality hazard for humans, and ultimately cause soil acidification if redeposited. The amount of nitrogen lost to volatilisation varies from region-to-region depending on soil properties (pH, moisture and texture), the climate and weather.
Nitrification
This is vital step in the nitrogen cycle as it is a mechanism used by microorganisms to obtain energy. Nitrification proceeds in two conversion steps: microorganisms firstly convert ammonium (NH4 ) into nitrite (NO2 ), this is then subsequently converted into nitrate (NO3 ). Nitrates provide nitrogen to crops in an optimal and highly available form. But their highly mobile nature also makes nitrates susceptible to leaching and groundwater pollution.
Denitrification
This is natural soil microbial process that converts nitrate into three gaseous forms of nitrogen – nitric oxide (NO), nitrous oxide (N2 O) and nitrogen (N2 ) – which can then be lost to the atmosphere. The process is generally promoted in water-logged soils where oxygen supply is limited and bacteria therefore consume the oxygen present in nitrate for respiration instead.
Although the above three processes are all natural and an integral part of the nitrogen cycle, nitrogen losses need to be drastically reduced to a level that does not inflict harm on ecosystems, the environment and the planet. n
Enhanced efficiency fertilizers (EEFs)
The development of urease and nitrification inhibitors as fertilizer additives has been a major advance in agricultural technology. These nitrogen inhibitors, by protecting against ammonia volatilisation and nitrification respectively (see box), significantly reduce nitrogen losses associated with urea application while helping to maximise crop yields. Crop nutrient products that incorporate nitrogen inhibitors are generally termed enhanced efficiency fertilizers (EEFs) or stabilised fertilizers (SFs).
The use of EFFs, by optimising nutrient use efficiency, has proven to be extremely helpful in intensive farming systems. Improving use efficiency, especially that of nitrogen, significantly reduces the adverse environmental effects of fertilizer use by increasing crop nutrient uptake.
The rate of nutrient release from fertilizers generally depends on factors such as rainfall, humidity, climate/weather and soil properties (pH, moisture, texture, microbes etc.). However, EEFs include two other groups of products that can act to slow or control the release of nutrients, these being known as slow-release fertilizers (SRFs) and controlled-release fertilizers (CRFs), respectively.
Neelam Aqua & Speciality Chem Ltd
Established in India in 1980, Neelam Aqua & Speciality Chem Ltd is a market leader in fertilizer additives. The company has expanded over the last four decades, with 11 factories and manufacturing units across the world now providing easier access to its products.
Neelam Aqua has constantly developed and championed technologies able to overcome the low nutrient efficiency exhibited by so many fertilizers. The company has also promoted the smooth transition to sustainable agriculture in both India and the Middle East by launching a plethora of sustainability initiatives – most notably the ‘per drop per crop’ campaign to address the high level of water usage in agriculture. This has emerged as a pressing problem in water-scarce countries.
Neelam Aqua manufactures a wide range of fertilizer coatings and additives designed to improve product quality. These include anticaking, colouring and dust suppressant agents. The company’s Neelcoat 1N 1000 product is an effective controlled-release additive for nitrogen fertilizer that also provides anticaking and dust suppressant properties. Neelam Aqua also offers three Urecoat anti-caking formulations for urea: Urecoat 2000 is specifically designed for prills, Urecoat 2002 contains a urease inhibitor, and Urecoat 2002N incorporates neem oil.
These speciality products are generally derived from plant extracts and are fully biodegradable. By creating enhanced efficiency fertilizers, they also have a role to play in the global mission to make agriculture more sustainable. n
SRFs and CRFs are designed to slowdown or regulate nutrient release throughout the growing season so it is more in sync with the needs of crops. This helps to overcome the problem of rapid and excessive nutrient release associated with conventional commodity fertilizers. The use of SRFs and CRFs also avoids the necessity for repeated split applications of fertilizers later in the season which are generally required to maintain nutrient supply.
The use and popularity of enhanced efficiency fertilizers is growing with sales of stabilised, slow-release and controlled-release types generally increasing. Although only applied on farmlands in a few parts of the world currently, EEFs are helping global agriculture become more sustainable and therefore benefiting the environment and the planet.
Conventional fertilizers can be turned into enhanced efficiency fertilizer using additives and coatings supplied by companies such as Neelam Aqua (see box). As well as improving nutrient use efficiency, these agents can also provide valuable anticaking and dust suppressant properties.
