Fertiliser labels explained

Ice breaker Individual activity What are fertilisers What do they do What do we mean when we say organic and inorganic fertlisers

Learning outcomes Why we use fertlisers Locate information from the label Current legislation and how it is enforced Statutory declaration

The contents of fertilisers, as described on the packet can seem quite daunting. However, labels explain the composition and nutrient content of the product, helping you to decide what you need to buy and how best to use it.

Why use fertilisers Although not always essential if plenty of well- rotted organic matter is available, fertilisers are extremely useful in maintaining soil fertility so that gardens thrive. Fertilisers are especially useful for plants in pots, fruit and vegetables. Fortunately fertiliser labels contain essential information to get the best from them.

Student activity 1 List the ways in which fertiliser can be purchased Liquid Pellets Soluble powders Granules

Activity In your group, what is the difference between granule and pellet fertiliser.

Information on the label All fertiliser labels have to display the same basic information. This allows one garden-fertiliser packet to be compared with another and should show clearly what is being bought.

Student activity 2 In your group list as many pieces of information you can find on the label.

Current legislation The composition, packaging and labelling of fertilisers in Great Britain is controlled by legislation. This may be either British or European; both differ slightly in their content, with EC regulations becoming more prevalent, but both are satisfactory.

Student activity 3 In your paired group discuss and formulate information to create a classroom discussion.

Statutory declaration Fertiliser packaging is required by law to include a number of details, including the following: The prescribed name of the product content, such as ‘NPK Fertiliser' The major nutrient contents, nitrogen (N), phosphorus (P) and potassium (K) Forms in which the nitrogen content is present Solubility of the phosphorus content: P and K are usually expressed as their oxide content, followed in brackets by the content of the element

Cont... Levels of secondary nutrients present such as magnesium (Mg) and other trace elements Any pesticide content (lawn weed-and-feed products, for example) as well as a statutory declaration to comply with pesticide legislation The name and address of the manufacturer The guaranteed weight of the product An EC product declaration, if the product is EC approved

Understanding labels Elements, such as nitrogen, phosphorus and potassium are the most useful part of fertilisers, rather than compounds such as phosphorus pentoxide and potassium oxide. So you will usually see on a label two ratings, one for the compound (oxide) rating, and then in brackets, the actual rating for the element. It will often appear as so: Potassium oxide soluble in water: 7% (5.8% K)

Examples Growmore has a ratio of 7:7:7 for these materials, but is actually 7 percent nitrogen, 3.1 percent phosphorus and 5.8 percent potassium, or 7:3.1:5.8. Therefore it is a high-nitrogen feed, rather than the ‘balanced’ fertiliser commonly assumed As garden soils are more likely to lack nitrogen than other elements, Growmore is deservedly popular, especially as a spring fertiliser

Student activity 4 In your group explain the information from the labels. Describe at what time of year the fertilsers would be applied.