Fertiliser recommendations for crops
Crop fertiliser recommendations from the Defra Fertiliser Manual RB209, including choosing, applying and managing fertilisers and manures.
Fertiliser planning is central to nutrient management, which is central to the yield and quality of crops from your land and is part of cross compliance for farms in Nitrate Vulnerable Zones (NVZs). The Fertiliser Manual (RB209) is published by the Department for Environment, Food and Rural Affairs (Defra) and sets out fertiliser recommendations for agricultural and horticultural crops.
This guide explains RB209 recommendations about the most cost-effective use of lime, major nutrients (nitrogen, phosphorus, potassium, sulphur, magnesium, sodium) and trace elements. It also provides information about choosing and applying fertiliser and organic manures, using the RB209 recommendation tables, and suggests organisations that can advise you on fertilisers and nutrient management.
Nutrient management with the help of the Defra Fertiliser Manual (RB209) - will help you:
- assess the fertiliser you need for the range of crops you plan to grow
- understand which level of nutrients is required to provide the best financial return for your farm business
- take proper account of both mineral fertilisers and other sources of nutrients such as manures and slurries to avoid costly over-application
- comply with the cross compliance requirements to protect your land and the environment including watercourses
As crops obtain nutrients from several sources, it is essential to carry out integrated plant nutrient management of all the sources from which crops obtain these nutrients, including:
- mineralisation of soil organic matter (all nutrients)
- deposition from the atmosphere (mainly nitrogen and sulphur)
- weathering of soil minerals (especially potash)
- biological nitrogen fixation (legumes)
- application of organic manures - including non-livestock sources (all nutrients)
- application of manufactured fertilisers (all nutrients)
- other materials added to land - eg soil conditioners
For optimum nutrient management, the total supply of a nutrient from all the above sources must meet, but not exceed, crop requirement.
For more information on nutrient management and cross compliance, see the guides on managing nutrients and fertilisers and the basics of cross compliance.
Environmental Stewardship (ES)
If you complete a Nutrient Management Plan - Option EM2 of ES agreements - you can gain points towards your ES agreement. For more information, see the guide on ES: the basics or download the Tried and Tested Nutrient Management Plan from the Agricultural Document Library (ADLib) website (PDF, 1.57MB).
Fertiliser Recommendations for Agricultural and Horticultural Crops (RB209) and the Fertiliser Manual
The Fertiliser Recommendations for Agricultural and Horticultural Crops - RB209 - provide information about the most cost-effective use of lime and major nutrients (nitrogen, phosphorus, potassium, sulphur, magnesium, sodium), as well as nutrients from organic manures. It also advises on nutrient management and protecting the environment from diffuse nutrient pollution.
The Fertiliser Recommendations were published in 2000 by Defra and are due to be replaced in autumn 2009 by the Fertiliser Manual.
Until the 2009 Fertiliser Manual becomes available, you should use technical updates or get information from a current Fertiliser Advisers Certification and Training Scheme (FACTS) qualified adviser when you use the 2000 edition of RB209.
The software for Planning Land Applications of Nutrients for Efficiency and the Environment (PLANET) is the free, interactive, computerised version of RB209. Farmers and advisers can get a free download of PLANET software, or a free copy of the PLANET CD - find PLANET software, documents, patches and updates on the PLANET website.
PLANET is also incorporated in several commercial software packages for farmers.
Planning applications of lime and nitrogen
A deficiency in essential plant nutrients and trace elements can restrict crop growth. An excess can cause crop growth problems and risks environmental pollution. Maintaining a balance between nutrients is also important, because they can interact with each other and too much of one can stop others from working. The Fertiliser Manual (RB209) advises on how to plan applications of lime and nitrogen based on the properties of your soil.
Understanding soil physical properties
In each field you will need to know the soil texture, organic matter content, potential rooting depth, soil stone content and soil parent material - each of these affect how fertilisers act on crops. For information on identifying your soil type, see our guide on managing soil types.
Soil acidity and liming
Soil pH affects the amount of lime to use on your fields. The range of optimum soil pH varies for different crops and soil types. The recommended amount of lime also depends on soil texture and organic matter. RB209 describes the available range of liming materials, and when to apply them.
Planning the use of nitrogen fertiliser for field crops
Before applying nitrogen fertiliser, you need to take account of the nitrogen supply and loss process which determines the amount of nitrogen in your soil. You can do this by assessing the:
- Soil Nitrogen Supply (SNS) in each of your fields every year, using an SNS index value from zero to six
- mineral nitrogen residues after harvest, but before leaching
- nitrogen leaching losses using excess winter rainfall
- nitrogen released from mineralisation of organic matter
To work out the SNS Index of your soils, you can use the Field Assessment Method, or the Soil Mineral Nitrogen (SMN) Analysis Method. SMN analysis is recommended if you expect high or uncertain amounts of soil nitrogen. For field assessment of SNS, you need information about the soil type, previous cropping, previous manure and fertiliser use and winter rainfall.
After calculating the SNS, there are three more calculations to make in planning nitrogen fertiliser use:
- the crop nitrogen requirement - the optimum amount of nitrogen to apply to a crop, taking into account the SNS
- the crop nitrogen available from any planned applications of organic manure
- the amount of manufactured nitrogen fertiliser you need to apply
Crops take up different sources of nitrogen with varying degrees of efficiency. Almost 100 per cent of SMN within rooting depth is taken up by the crop. Winter wheat and winter barley uptake of fertiliser nitrogen is less efficient, and varies with soil type. RB209 recommendations for fertiliser use take account of these differences in efficiency of uptake.
You can find out more about planning your use of nitrogen fertiliser in the guide on managing nutrients and fertilisers.
You should time applications of nitrogen to coincide with the start of rapid crop growth and nitrogen uptake.
Generally, nitrogen is best applied across the whole cropped area. But for wide-row crops, band placement of nitrogen improves crop performance and reduces fertiliser costs and the risk of nitrate pollution of water.
Planning applications of essential nutrients
The Fertiliser Manual (RB209) advises on planning the application of essential nutrients to your soil. Planning the nutrient quantity carefully enables you use nutrients in a cost effective way that provides the best crop yields and minimises risks of environmental pollution.
Phosphorus and potassium
Phosphorus and potassium are available in soil reserves, fertilisers or organic manures. Different types of manures have different amounts of phosphorus and potassium.
Excessive levels of phosphorus in soil are financially wasteful and likely to cause pollution of surface waters, leading to eutrophication. This causes algal blooms and can destroy aquatic life.
In order to plan your use of phosphate and potash fertilisers you need to know:
- soil indices for phosphorus and potassium, from soil sampling and lab analysis - to be done every four years
- target soil indices for phosphorus and potassium for the crop
- phosphorus and potassium application policies
- whether you need to build up or run down the soil phosphorus or potassium index
Soil analysis will show the quantity of available magnesium in soil, expressed as an index.
Magnesium deficiency will cause potatoes and sugar beet to show deficiency symptoms and their yield may improve when magnesium fertiliser is applied.
In the past, sulphur was supplied to plants through rainfall and fertilisers that contain sulphur as a by-product. But sulphur in rainfall is declining, bringing a risk of sulphur deficiency in crops including cereals, brassicas, peas, oilseed rape and grass. Crop symptoms of sulphur deficiency are hard to tell apart from nitrogen deficiency.
To assess the risk of sulphur deficiency you will need:
- knowledge of soil type and field location
- a leaf analysis of cereals, oilseed rape and grass
- a soil analysis of sulphur levels
Crops such as sugar beet and carrots need sodium. Soil sampling and lab analysis will identify if you need to apply sodium fertilisers.
Trace elements or micronutrients
Most micronutrients or trace elements are naturally adequate in soils in England - only manganese is commonly deficient. This affects mostly sugar beet, cereals and peas grown on acidic peaty, organic and sandy soils. Symptoms of manganese deficiency in crops are similar to those created by other crop growth problems, so you will need to use plant/soil analysis to confirm a trace element deficiency.
Other trace element deficiencies that affect crop growth:
- boron - can affect sugar beet and brassica crops on light soils with a pH above 6.5
- copper - can affect cereals and sugar beet on certain soil types
- iron - affects fruit crops grown on chalky soils
Deficiencies affecting livestock
Deficiencies of cobalt, copper and selenium in grazing animals will not affect grass growth - it’s best to treat the animals directly with the missing trace element, rather than applying them to the grass.
Choosing and applying fertiliser
There are many types and qualities of fertiliser in both solid and liquid forms. Before deciding which to buy, you need to consider:
- the total concentration and ratio of nutrients in the fertiliser - the concentration will affect the amount you apply and the ratio should be close to your planned nutrient needs
- the chemical form of each nutrient - different chemical forms of a nutrient may be taken up by crops more or less effectively
- the physical quality of a solid fertiliser and whether you will be able to spread it accurately - different sources of supply of the same fertiliser type can be physically quite different and some will be easier to apply accurately than others
- the cost of the nutrients - this can vary significantly, and cheaper fertilisers may be poorer quality and so a false economy
Nitrogen fertilisers include ammonium nitrate, ammonium sulphate and calcium ammonium nitrate.
Water-soluble phosphate fertilisers are quickly taken up by crops. Water-insoluble phosphate fertilisers come in different concentrations and types and you will need to assess them for suitability.
Nutrients in most sources of potash fertiliser are quickly available to crops. Magnesium fertilisers vary in how quickly or slowly crops can take up their nutrients.
Accurate and even fertiliser application will maximise crop yields and profitability. Inaccurate, uneven application can cause problems such as:
- uneven crops, lodging and disease, and reduced yields and quality at harvest
- nutrient pollution of watercourses at field margins
- changes to biodiversity in hedgerows and field margins
You need to regularly maintain and service fertiliser spreaders and sprayers.
Protecting the environment from diffuse nutrient pollution
To avoid polluting watercourses and groundwater, make sure that you don’t apply more fertiliser than the crops require and that you apply fertiliser close to the time when the plants will take it up. This will minimise leaching of nutrients.
Ammonia emissions from livestock manures and nitrogen fertilisers contribute to acid rain and damage nitrogen-poor habitats such as heathland. To find out how to reduce ammonia emissions see the guide on sewage sludge, slurry and silage.
To avoid eutrophication caused by phosphorus pollution of watercourses:
- plan phosphorus applications carefully
- avoid surface application of organic manures when soil and weather conditions are likely to lead to run off
- apply small annual dressings of fertiliser, which you work into the soil surface before winter
You can produce organic manures on your farm from slurries, farmyard manures and poultry manures, or you can buy treated sewage sludges (biosolids) and some industrial wastes.
You can find out more about organic manures in the guide on sewage sludge, slurry and silage.
You can find further detail in Section 2 of The Fertiliser Manual (RB209). You can download Defra’s RB209 from the Agricultural Document Library (ADLib) website (PDF, 4.47MB).
Farm animal manures and slurries
You can find out how to prepare an organic manure sheet using the Tried and Tested Nutrient Management Plan. You can download the Tried & Tested Nutrient Management Plan from the ADLib website. (PDF, 1.57MB).
Good practice in applying manure includes:
- minimising nitrate-leaching losses by applying in spring
- band spreading to allow accurate slurry topdressing and reduce ammonia emissions - rear discharge spreaders spread slurry and manure more evenly than side dischargers
- applying cattle slurry in spring to grasslands where you intend to produce silage or hay
- not grazing pasture for four weeks after you have applied slurry or solid manure, or until all visible signs have disappeared
- sampling the soil periodically to test for heavy metals, if you apply pig or poultry manures to the same land over several years
Nitrate Vulnerable Zones and nitrate pollution
Nitrate pollution is a particular problem for over 60 per cent of agricultural land in England. In England, nitrate regulations implement the European Community’s Nitrates Directive, with the aim of reducing nitrogen losses from agriculture to water. In areas where nitrate pollution is a problem, you must follow practices set out in the Defra guidance. These also form cross compliance Statutory Management Requirement 4 which must be followed in order to receive direct farm payments. For more information, see the guide on NVZs.
Manure Nitrogen Evaluation Routine (MANNER)
MANNER is a free, decision-support software system that you can use to predict the precise fertiliser nitrogen value of organic manures on a field-specific basis. In this way, you can avoid applying too much or too little nitrate, either of which could adversely affect crop yields and quality.
Sewage sludges (biosolids)
For information on using sewage sludge on your farm, see the guide on sewage sludge, slurry and silage.
Find out about cross compliance Statutory Management Requirement 3 - Sewage in the guide on managing nutrients and fertilisers (includes tool).
Safe sludges to apply to your land include digested cake and liquid sludges. You can also use lime-stabilised, thermally-dried and composted sludges. These are supplied by water companies and come with nutrient-content data and other information.
Nitrogen supply from sludges is affected by the same factors that affect supply and losses of nitrogen from farm manures.
You can spread some industrial wastes onto your farm land. If you intend to do so you must register with the Environment Agency, who will advise you on how to follow relevant regulations.
Using the RB209 recommendation tables
The Fertiliser Manual (RB209) include tables to help you find recommended amounts of plant nutrients and trace elements for specific crops, specific soil types and specific rainfall areas.
Arable and forage crops
The recommendations cover:
- a checklist for deciding on fertiliser use
- guidelines on when to apply fertiliser, depending on crop and soil type
- which nutrients to apply
- how to use grain nitrogen concentration analysis to review your nitrogen strategy for cereal-crops land
- how to use organic manures in maize rotations
Vegetables and bulbs
The recommendations cover:
- a checklist for deciding on fertiliser use
- the main principles of fertiliser use for vegetables - including use of starter fertiliser, band spreading of nitrogen, ploughing in nitrogen-rich crop residues and availability of soil nitrogen for shallow-rooted crops
- when to apply fertiliser, depending on crop and soil type
Fruit, vines and hops
The recommendations cover:
- a checklist for deciding on fertiliser use
- guidance on how and when to sample soils before planting fruit, vines and hops
- guidance on how and when to sample soils for established orchards, soft fruit plantations and hops
- optimum soil acidity for fruit crops, and guidance on liming before planting and liming established crops
- diagnosing and correcting magnesium and trace elements deficiencies
- applying fertiliser for fruit vines and hops before planting
- nitrogen recommendations for top fruit and established orchards, depending on soil management system and soil type
- fertigation of young apple trees
The recommendations cover:
- an annual checklist for deciding on fertiliser use for grassland
- the principles of fertilising grassland
- how to protect the environment from pollution by nitrates, ammonia and phosphorus
- how and when to use the recommended amount of nitrogen fertiliser, based on a field’s SNS status, Grass Growth Class and intended use of the grassland, as well as weather during the growing season
- how and when to use the recommended amount of phosphate, potash, magnesium and sulphur
Case study: Here’s how I used fertilisers to improve my crops
Andrew’s top tips:
- “Use yield mapping to check your yields. After all, the crop is the best thing to tell you how you are doing.”
- “Keep robust records. It’s important to know how much fertiliser you put on each crop to understand the economics of it.”
- “Don’t let technology take your eye off the ball and make you forget the basics such as agronomy and calibration.”
Andrew Cragg has been farming Brooker Farm in Romney Marsh, Kent since 1980. He grows winter wheat, rape and vining peas over 600 hectares and employs three people. Here he explains how fertilisers are maintaining his yields.
What I did
Use precision soil-sampling techniques to map my requirements
“I look not only at each of my fields in turn, but also within the fields in order to understand the phosphorous and potassium variations in the soil. Using the Global Positioning System (GPS) is essential for this because it tells me where I am in the field. Having a map of my soil showing how the nutrients vary between and within the fields means I apply nutrients only where they are required. It also means I even out my yields on these areas and I minimise the environmental impact of blanket applications.
“I don’t nutrient map everywhere because it wouldn’t be cost effective, but I do it where I suspect I have levels of variation. I also do pH mapping using the same principle - putting lime on only where I really need it.”
Keep an eye on micronutrients
Sometimes I do foliar testing. I take a sample of the crop in the spring and send it away so they assess the presence of micronutrients in the crop itself. I only do it if I suspect a serious problem though.
“Last year I did it with the oilseed rape and it showed it was a little low on some key micronutrients so I used a foliar-applied nutrient mix. It’s difficult to know whether it was effective or not but you have to go with your intuition. To not take action is to take a risk.”
Choose a product with care
“I choose a fertiliser that is good quality for the method by which I spread it. I spread with a twin-disc spreader so I buy a product with a good granule size.
“My other consideration is the strength of the product. I favour 46 per cent urea because you get more of it in a tank than 34.5 per cent ammonium nitrate, and it goes further. I also go for straights rather than mixes. Because of my soil type I rarely need potassium so straights are more cost effective. In short, it’s about quality, strength and value.”
What I’d do differently
Invest in the right tools at the start
“I’ve bought a variable bout-width controller for my spreader. This uses GPS to tell the spreader where it is in the field and it reduces the width of the spread as it approaches an angled headland at the field boundary to reduce overlapping. It has a clear economic and environmental benefit. I wish this had been available earlier.”
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