Use of all agricultural inputs is under increasing scrutiny as the race to decarbonise all aspects of UK life to achieve ‘net zero’ gains momentum, says Dr George Fisher of CF Fertilisers.
As one of the food industry’s main drivers behind the high levels of production we have come to rely on, nitrogen use is very much in the spotlight and will continue to be so, believes Dr George Fisher.
He says: “As far as manufacturing and management of nitrogen onfarm is concerned, much has already been achieved.
“I do not think any of us should downplay the size of the task ahead and there is a lot to be done across all aspects of our lives, but the journey is well and truly underway as far as fertiliser use is concerned.
“According to the UK Office of National Statistics, greenhouse gas emissions from agriculture dropped from 58.9 million tonnes CO2 equivalent to 45.6m tonnes between 1990 and 2017 – a drop of nearly 23 per cent and sound evidence that the agricultural industry is taking carbon reduction seriously.” While new legislation and guidelines will develop quickly over the next few years, there are some basic steps all producers should be taking now to ensure their nitrogen fertiliser use remains as carbonefficient as possible, he says.
Fertiliser production is a complex process with varying efficiencies of manufacturing so whether the fertiliser being applied is from an abated production site is the first stage of being carbon responsible, Dr Fisher points out.
“CF Fertilisers has made major steps in recent years to reduce the greenhouse gas emissions associated with fertiliser production through investment and working with the Carbon Trust.
“The simple fact is that nitrous oxide (N2O) is an unavoidable by-product of the fertiliser manufacturing process and it is a significant greenhouse gas so an important area of focus has been to install state-of-the-art N2O abatement technology on the nitric acid plants at Billingham.
“A multi-million pound investment programme in manufacturing facilities has reduced production of N2O emissions by 3,000t every year.
“As a greenhouse gas, N2O is 300 times more powerful than CO2 in terms of its effect as a greenhouse gas, so that is equal to a reduction of 900,000 tonnes of CO2 .
“This is equivalent to the whole of the 30 per cent CO2 reduction required by UK agriculture by 2022, so it is a sizeable amount and a major achievement.
“All told, we have reduced the carbon footprint of nitram production by 40 per cent since 2010.”
Carbon audits will become an increasingly important part of life for all agricultural producers in the future with the robustness of data used in these being essential in achieving compliance and maximising the value of farm produce, Dr Fisher says.
“We took the decision some years ago to look into the carbon footprints of our products and that in order for these to carry maximum credibility we should work with the independent Carbon Trust to produce these.
“To make the major improvements in manufacturing and emissions reduction as practically useful as possible to customers, it was also decided to produce business-to-business – or cradle to farmgate – fully audited and certified carbon footprints for our entire range of fertilisers as well as the ammonia and nitric acid used in their manufacture.” Today, CF is the only fertiliser manufacturer in Europe to have 100 per cent independently-verified carbon footprints across all its products and manufacturing processes, he says.
“Not only does this mean our carbon footprints have undergone rigorous independent scrutiny, they have also been calculated using the standards set out in the demanding internationally recognised PAS 2050 protocol and that is a first in fertiliser manufacture.”
Nitrogen fertiliser has the greatest return on investment of all inputs at about 5:1, so with a focus on making every kilo count from an environmental perspective, product choice is now even more critical, Dr Fisher says.
“Key factors affecting N utilisation include weather variability, application method and the form in which the nitrogen is delivered to the crop.
“Every producer, whether livestock or arable, should now carry out and follow a Nutrient Management Plan“
Dr George Fisher
“Ammonia nitrogen can be lost to the air following urea application through volatilisation and according to the definitive Defra research programme NT26 into UK fertiliser use, this can cut the amount of urea nitrogen available to crops by 22 per cent on average, with the worst case recorded being 43 per cent and it was even higher in grassland.” With AN, nitrogen is available to the plant as soon as it is applied whereas with urea, nitrogen release relies on the complex process of hydrolysis which is dependent on soil bacteria and the weather, he explains.
“Defra funded studies say that to maintain crop yields, the optimum N rate using urea would have to be, on average, 10 per cent higher than with AN.
“In a carbon-focused future targeting net zero, efficient use of every kilo of N produced will become critical making product choice equally so.”
Optimising N-use will mean an understanding of Nitrogen Fertiliser Use Efficiency (NfUE) will become increasingly important, Dr Fisher explains.
“NfUE gives growers a clearer picture of the impact their fertiliser choices are having on their production efficiency and carbon footprint – the higher the value the better.
“Crop NfUEs typically range between 50 per cent to 80 per cent with AN-based solid fertilisers tending to be at the top end of this scale and urea-based products, including liquids and blends, tending towards the lower end.” In independent trials, Nitram (34.5% N) outperformed straight urea in terms of NfUE across all trials conducted over two very different production years with an average of 74 per cent compared to 66 per cent for urea.
“This is the equivalent of an additional 16 per cent total loss of nitrogen from urea and in crops with an application rate of 200kg/ha N this would be equivalent to a loss of 32kg/ha N.” An important aspect of NfUE is applying the right amount of nitrogen fertiliser, at the right time, he adds.
“For arable crops and maize, CF Fertilisers’ N-Min service tells you how much nitrogen will be supplied by your soil over the season and calculates the best rates and timings, making sure that over or under application of N does not compromise your yields or carbon footprint per tonne of production at farm level.”
It is a good idea to start putting carbon-focused thinking at the forefront of your management thinking now, Dr Fisher advises.
“Every producer, whether livestock or arable, should now carry out and follow a Nutrient Management Plan and Carbon Audits will become increasingly important in the future, so it is a good move to start thinking this way now.
“Fortunately, decisions to improve the efficiency of your farm are also ones that will help increase its economic performance too.
This will be of rising significance in the years ahead as premium prices will become increasingly linked to the carbon footprints of production.
“Some milk buyers are already asking their suppliers to provide this information and one of the biggest elements of this is your fertiliser use.
“It is something we have been aware of for some years now and while the international standard figure is 6.6kg of carbon dioxide for every 1kg of N you use.
With CF ammonium nitrate (Nitram) it is almost half this at 3.4kg for every 1kg of N used.
“This is a result of the investment we have made in de-carbonising the manufacturing process and is tangible evidence of how fertiliser product choice will increasingly affect a farm’s overall viability in the future.”
With a target of net zero carbon emissions by 2040, there is still a long way to go.
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