‘Production and use of nitrogen fertilisers’ Report for Defra project NT2601
Report for Defra Project NT2601
Production and use of
Peter Dampney, ADAS Boxworth
Bill Basford, ADAS Gleadthorpe Grange
Gillian Goodlass, ADAS High Mowthorpe
Paul Miller, Silsoe Research Institute
Ian Richards, Ecopt
2.Glossary of terms......
4.Introduction and acknowledgements......
5.World consumption and production......
5.1Consumption of fertiliser N - world......
5.2Consumption of fertiliser N - EU-15......
5.3Production of nitrogen fertilisers......
5.4Use of different N fertiliser materials in EU Member States......
6.Supply of nitrogen fertilisers to farms in the UK......
7.Use of nitrogen fertilisers on farms in the UK......
7.1Overall nitrogen use and trends......
7.2Forms of nitrogen used by agricultural crops......
7.3Timing of nitrogen use......
7.4Methods of nitrogen application......
8.On-farm handling and spreading......
8.3Fertiliser spreading systems......
8.4Fertiliser application work rates......
8.5Spreading accuracy (solid N fertilisers)......
8.6Potential future trends......
1. AbbreviationsAC / Ammonium carbonate
ACl / Ammonium chloride
AN / Ammonium nitrate
APP / Ammonium polyphosphate
ATS / Ammonium thiosulphate
AS / Ammonium sulphate
ASN / Ammonium sulphate nitrate
AnA / Anhydrous ammonia
AqA / Aqueous ammonia
BSFP / British Survey of Fertiliser Practice
CAN / Calcium ammonium nitrate
CC / Calcium cyanamide
CN / Calcium nitrate
Chilean CN / Chilean potassic nitrate
CPA / Crop Protection Agency
CV / Coefficient of Variation
CDU / Crotonylidenediurea
DAP / Di-ammonium phosphate
ENTAM / European Network for Testing Agricultural Machines
FMA / Fertiliser Manufacturers Association
FSU / Former Soviet Union
HSE / Health and Safety Executive
IBC / Intermediate Bulk Container
IBDU / Isobutylidene urea
MgAP / Magnesium ammonium phosphate
MgN / Magnesium nitrate
MS / Member State
MU / Methylene urea
MAP / Mono-ammonium phosphate
MOP / Muriate of potash
N / Nitrogen
OSN / Other straight nitrogen
Ox / Oxamide
KN / Potassium nitrate
PSDS / Product Safety Data Sheet
SSP / Single superphosphate
NaN / Sodium nitrate (nitrate of soda)
S / Sulphur
SCU / Sulphur coated urea
TSP / Triple superphosphate
U / Urea
UAN / Urea ammonium nitrate
UAS / Urea ammonium sulphate
UCN / Urea calcium nitrate
UP / Urea phosphate
2. Glossary of termsBlended fertiliser / Compound fertiliser produced by dry mixing of two or more different particulate or powder materials.
Bulk density / Density of a mass of material, often expressed as kg/litre. The mass comprises the particles and the air spaces between them so bulk density is determined by the shape and size of particles as well as by the true density of the material from which the particles are formed. Particulate materials show differences in bulk density between loose and tamped or shaken states, in some materials as great as 15%. The bulk densities shown are intended to describe those of material in a spreader hopper. A value of 1.00 kg/l means that a 1000 litre hopper should hold 1tonne of material.
Caking / Formation of large hard agglomerations of fertiliser particles due to chemical properties of the materials or to absorption of water. This phenomenon occurs when fertiliser granules adhere to one another through crystal bridges or plastic deformation.
Complex fertiliser / Compound fertiliser where all particles have the same composition.
Compound fertiliser / Product containing more than one of the major nutrients.
Deliquesce / Absorption of atmospheric water vapour resulting in the loss of physical structure of particles.
Fluid fertiliser / Products supplied in liquid form, either as solution or suspension.
Granulation / Methods of forming fertiliser particles, mainly in the range 2 to 4mm. There are two main classes of granulation: slurry and non-slurry processes. In slurry processes, solid particles of the fertiliser (obtained through recycling of undersize particles) are coated with a slurry of the fertiliser in successive layers. In non-slurry processes, a liquid component is added to finely divided particles causing them to agglomerate. Most granular products are slightly irregular in shape but some, those made by fluidised bed processes for example, are nearly spherical.
Granular fertiliser / Solid fertiliser where particles are all produced by granulation. May be complex or blended though the term is sometimes erroneously used as an alternative to complex.
Hygroscopic / Material absorbs moisture from the air.
IBC / Intermediate bulk container or big bag, usually containing 500, 600 or 1000kg of fertiliser. IBC also can refer to 1m3 containers of solution fertiliser.
Median size / The particle size at which 50% of the material by weight is smaller and 50% larger. The median size can vary in some materials and the values shown should be treated as guides. The particle size for most manufactured granular and prilled fertilisers is in the range 2 to 4mm range.
Particle crushing strength / Force that must be applied to cause a particle to shatter or break. Measured in newtons (N).
Particle or true density / Density of the solid material from which the particles are formed. Particle density therefore is independent of particle size and shape. The weight of a particle is determined by it’s size and density and is an important factor in spreading properties.
Prilling / Method of particle formation in which the molten fertiliser is forced through holes in a metal disc or spinning bucket and allowed to fall as droplets in a tower. The particles solidify as they fall. Prills tend to be more spherical and slightly smaller than granules
Solution fertiliser / Products where the nutrients are present in true solution.
Straight fertiliser / Product containing only one of the major nutrients (nitrogen, phosphate or potash)
Suspension fertiliser / Products where the nutrients are present partly in solution and partly as finely divided particles in suspension.
3. Executive summary
- This report forms part of the NT2601 project for Defra. It describes and discusses the production and use of nitrogen (N) fertilisers both worldwide and in the UK. Current methods for on-farm handling and spreading are discussed including the spreading accuracy of different nitrogen fertiliser materials. The information sources are published international literature and information provided by representatives of the UK and international fertiliser industries. Other reports from the NT2601 and 2602 projects cover ‘Nitrogen fertilising materials’ and ‘Evaluation of urea-based nitrogen fertilisers’.
World consumption and production
- The world consumption of N fertilisers has roughly doubled in the last 30 years due mainly to an increase in the use of urea. Urea now represents around 50% of the world’s use of N in manufactured fertilisers.
- The EU-15 uses around 9 million tonnes of N as fertiliser each year of which the UK uses around 1.1 million tonnes (13% of the EU total). Overall in EU-15, over 40% of all N used as fertilisers are AN-based (AN or CAN), 13% as solid urea, 11% as UAN solution and 22% as compound fertilisers. The accession of notably Lithuania and Poland to the EU will increase the total amount of AN produced, exported and used within the EU-25. Due mainly to historical production or nearby supply factors, Member States differ in the main forms of N fertilisers used. The UK and France are the main users of AN with significant use by Denmark, Greece, Italy, Spain and Sweden. CAN is widely used. France, Germany, Italy, Spain and the UK use significant amounts of urea. UAN solution fertiliser is used especially in France, Germany, Spain and the UK.
- There is manufacturing capacity within the EU-15 for all the main types of N fertiliser (AN, CAN, urea, UAN, compounds). Most Member States maintain domestic production of one or more straight N fertilisers. AN is produced in seven Member States. 18% of the world production capacity of AN, and 63% of the production capacity of CAN is in EU-15. However, this is insufficient to meet the demand for these products so AN is imported from outside EU-15, mainly the FSU. Only 3% of the world urea production capacity is located in the EU-15.
- Around 30% of the total world production capacity of urea produces granular rather than prilled urea (granular urea is likely to be the preferred physical form of urea for use in the UK). There are 6 existing production sites for granular urea within the EU-15; this represents about 60% of the total urea production capacity in the EU. However, current consumption of granular urea in EU-15 exceeds this productive capacity so there is a current EU reliance on imports. Current world capacity exceeds demand with Latin America and the Middle East as the main exporting regions.
Supply of N-containing fertilisers in the UK
- The current UK manufacturing capacity is focused around ammonia plants at Billingham, Teeside and Avomnouth (operated by Terra Nitrogen) and Ince, Cheshire (operated by Kemira). Some ammonia goes for industrial purposes but around 600,000 tonnes of N as straight or compound N-containing fertilisers is manufactured annually mainly for domestic use but some for export. This supplies about 50% of the UK annual demand for fertiliser N.
- About 50% of the current UK demand for fertiliser N is imported mainly as AN but also as urea, compound N and UAN solution. There are large fluctuations in both import quantities and the apparent origins of production though trading volumes within EU-15 are less volatile than those outside this zone. Imports will arrive by ship in bulk or big bags. Any significant increase in imports may create local problems of dockside storage and/or bagging capacity, though loading/offloading facilities should be less of a problem.
- Virtually all N-containing fertilisers are supplied to farms in ‘big bags’ commonly 500 or 600kg in size. Any reduction in the average N concentration of fertilisers used in the UK will have knock-on effects by increasing the volume and weight of materials for handling, storage and national distribution by road. Most fertilisers are transported by road.
Use of N-containing fertilisers on UK farms (data from British Survey of Fertiliser Practice 2002)
- A total of 1.1 million tonnes of fertiliser-N was used in the UK in 2002. This shows a continuing trend of declining use since the mid 1980s. Overall, N application rates as kg/ha N have remained steady on tillage land but gradually declined on grassland (c. 24% reduction between 1985 and 2000). 67% of all nitrogen used in the UK is used in England.
- A significant proportion (35%) of all N used in the UK is applied as compound-N; the remainder is applied as straight N. The majority (66%) of N used on grassland is applied as high N compounds (over 20% N content). These materials also contain other nutrients but require AN as a raw material in their manufacture. Blended fertilisers require solid AN, complex fertilisers can be made from AN liquor. Only 15% of the N used on tillage crops comes from compound fertilisers; 85% of the N is applied as straight N materials and an increasing proportion of this total is of fertilisers which contain sulphur (S) as well as nitrogen (NS fertilisers in the BSFP are classed as straight fertilisers not compounds).
- The main straight N material used is AN. Over 60% of the total use of straight N is applied to tillage crops in England. The other main sources of straight N are solid urea and UAN solution, but there is very little use of these materials on grassland. Grassland farmers currently rely heavily on the N contained in solid compound fertiliser materials.
- In 2002, c.100,000t N as solid urea was used (c.9% of total N use); 95% of this urea was applied as topdressings to winter cereals, oilseed rape or grass. Very little urea (2% of total) was used on spring cereals and virtually none on potatoes, sugar beet or horticultural crops - this may reflect concerns about possible crop phytotoxicities from use of urea to these crops.
- Overall, 106,000t N of fluid N is used (c.10% of total N use) of which 92% is as straight UAN. Nearly 90% of the total use of fluid-N is in England. c.80% of straight UAN is used on winter cereals. Fluid-N fertilisers are used significant proportions of several crops:- potatoes (30% of cropped area as straight and compound fluid-N materials), winter cereals (18% of cropped area as straight UAN), oilseed rape (15% of cropped area mainly as straight UAN), and horticulture (11% of cropped area as compound fluid-N). Very little fluid-N is used on grassland. About 890,000ha (15%) of winter cereals received fluid-N, and 55,000ha (30%) of the potato area. Fluid fertilisers are mainly used by cereal, general cropping and mixed farms with very little use on all-grassland farms. About 890,000ha (15%) of winter cereals received fluid-N, and 55,000ha (30%) of the potato area. Fluid fertilisers are mainly used by cereal, general cropping and mixed farms with very little use on all-grassland farms.
- Over 900,000t N (82% of total annual use) are applied to land in the 3 months of March, April and May. Most straight N (87% of total N use) is applied during these months but only 73% of compound-N. During the commonly warm and dry months of May, June, July and August (when there may be a particularly high risk of ammonia loss following urea application), c.330,000t N are applied to land (c.30% of total N). Of this, c.150,000t N are applied as compound-N (c.40% of total compound-N use), and c.180,000t N as straight N (25% of total straight N use).
- Nearly 80% of solid urea and fluid UAN is applied in February, March and April when soil and weather conditions are more likely to be cool and moist. Only 12% of urea-N is applied in the warm and dry months of May, June, July and August suggesting that farmers may perceive a poor efficiency from urea applied at this time.
- Most N fertilisers are topdressed. Only c.37,000t N (3% of total N use) is either combine drilled, placed or applied in the seedbed. For a few crops such as spring barley, potatoes and field vegetables, N fertilisers may be placed or applied in the seedbed - e.g. 26% of the spring cereal area receiving N fertiliser has N applied ‘at drilling’ either in the seedbed or combine drilled.
- For potatoes, c.9000t N is either placed or applied to the seedbed, mainly as compound-N. This is c.50% of the total N use on potatoes (16% placed, 33% seedbed). Potato is the only crop that has significant amounts of N applied by placement. Urea-based N materials are not used for placement applications possibly because of risks of phytotoxicity. For horticultural crops, c.1000t N is either placed or seedbed-N, mainly as compound-N (75%) but some as straight N (25%). This is c.15% of the total N use in horticulture.
On-farm handling and spreading
- Most fertilisers are now handled as ‘big bags’ of between 0.5 and 1.2t capacity. Changes to on-farm storage and handling requirements may not cause significant problems, though use of materials with reduced N contents will increase handling and spreading costs.
- Over two-thirds of solid fertiliser spreaders are spinning disc or oscillating spout spreaders, with only 5% as pneumatics and 7% used for fluid fertilisers. Disc and spout spreaders need to able to ‘throw’ fertiliser far enough in order to achieve an acceptable overall spread pattern. Pneumatic spreaders can be more suited to spreading low density/small sized materials such as urea, but these spreaders are expensive to buy and maintain, and are more sensitive to poor material flow characteristics.
- The main issue of on-farm handling and spreading relevant to a possible change from AN to urea-based N fertiliser materials, is the ability to maintain acceptable distribution patterns where fertiliser spreaders are used at bout widths of 24m and over. In arable systems, a 24m tramline system is the common standard; only 2% of tramline systems are over 24m wide.
- Since urea has a lower density than AN, it can be more difficult to spread, particularly if associated with a small particle size. Many of the urea products commercially available in the 1990s and used in spreading assessments, had poor flow characteristics and a small mean particle size (<2.0mm diameter). Using disc type spreaders, these materials could not be spread with a fully over-lapping spread pattern at bout widths of 24m. Improved spreading characteristics could only be achieved by increasing particle size, increasing particle density or both.
- Granular urea materials are now commercially available with mean particle sizes which are substantially larger (e.g. 3.5mm diameter) than most other common fertiliser materials. These materials are likely to have significantly better spreading characteristics than small sized, prilled urea. However there is little data to define the spreading characteristics of granular urea materials. There is a need to study the spreading performance of these materials, to quantify the options for improving the spreading performance of urea-based materials from disc type spreaders to meet current spreading bout widths, and to define the commercial feasibility of using such materials.
- Urea-based fertilisers can be applied as fluid fertilisers (e.g. UAN) using modified sprayer equipment that is fundamentally the same as that used to apply pesticides. About 10% of the N used on arable farms is applied in fluid form but virtually none on grassland. The use of fluids can have advantages (e.g. no bags to dispose of, easier handling, better spreading accuracy) and disadvantages (e.g. grassland farms will not usually have a sprayer equipment).
4. Introduction and acknowledgements
This report describes and compares the production of different types of nitrogen fertilisers worldwide, and the supply and use of nitrogen fertilisers on farms in the UK. The report aims to provide baseline information of current practices.
Many of the statistics presented in this report refer to a single year. Because of the volatility of fertiliser trading and use, these statistics should be regarded as an indicative snapshot and not necessarily a reflection of a consistent pattern.
Section 5 describes the world consumption and production of different N-containing fertiliser materials.
Section 6 describes the supply of N fertilisers to farms in the UK.
Section 7 describes the use of N fertilisers on farms in the UK.
Section 8 describes the on-farm methods of handling and spreading fertilisers.
The information in this report has been obtained from published and unpublished information. The factual content of the report and appraisal of the information has been verified by the Fertiliser Manufacturers Association (FMA).
Cambridge University are acknowledged for providing information from the 2002 British Survey of Fertiliser Practice.
5. World consumption and production
(Lead author:- Ian Richards, Ecopt)
Manufactured fertilisers are produced in various physical and chemical forms. Most fertilisers are particulate solids with typical particle diameters of 2-4mm though some commercial products are in fluid form (solutions or suspensions).
‘Straight’ fertilisers contain one of the three major nutrients – nitrogen (N), phosphate (P2O5) or potash (K2O). Examples of straight fertilisers are ammonium nitrate (AN), calcium ammonium nitrate (CAN), urea, triple superphosphate (TSP) and muriate of potash (MOP).