Part one of a series of three articles written by Kevin Timms Sports Turf Advisor NZ Sports Turf Institute on the Facts Formulations & Fundamentals of Fertilisers.
Fertilisers and their use are at the core of successful, every-day turf management. Yet for many turf managers and prospective turf practitioners they remain somewhat of a mystery. Never before has the industry been so well served by such a myriad of products and formulations.
In order to make well informed decisions about the most appropriate option for any given situation it is first necessary to understand something about the 'building blocks' or facts, formulations and fundamentals that define and govern the use of many of the fertiliser products available today:
- Key fertiliser terms
- Fertilisers A-H
Key fertiliser terms
Chelated fertilisers Trace element fertilisers are often sold as chelates. A chelate is a substance formed between a metal and an organic compound. The organic compound enhances the water solubility of the metal, making it more readily available to plants. Iron is often sold in a chelated form.
Compound fertilisers Manufactured fertilisers where each granule contains the same nutrients in the same proportions. Formulations may be either granulated or prilled.
Fertiliser Any natural (organic) or manufactured synthetic (inorganic/organic) material that is added to the soil in order to supply one or more plant nutrients. A substance is defined as a fertiliser when it contains as least 5% in total of nitrogen, phosphorous, potassium, magnesium and/or sulphur in a form that promotes plant growth.
Fertiliser analysis The concentration of individual major nutrients expressed as a percentage. Always written in the order N: P: K: S: Mg. Generally the analysis percentages are rounded down to whole numbers and called the rating. Occasionally you see slight variations in the nutrient analysis of similar fertilisers made by different manufacturers.
Fertiliser mixtures Simple physical mixtures of two or more of the standard N.P.K fertilisers.
Foliar fertilisers Foliar fertilisers are specifically formulated in a small molecule size that will enter directly into the leaf. Trace elements may be added in a chelated form to provide an NPK + trace elements product.
Hydrolysis When urea or other products such as IBDU or methylene urea are applied to the soil they undergo a reaction with water. The fertiliser is 'hydrolyzed' to ammonium carbonate and then to the plant available ammonium form. This reaction is very fast (1-3 days) for urea or much slower in the case of the slow release IBDU or methylene urea products.
Inorganic fertilisers Inorganic fertilisers are formulations that are not animal or vegetable (carbon) based. These fertilisers are manufactured involving a process that converts raw materials into concentrated plant available forms.
Liquid fertilisers Water soluble liquid fertilisers are dissolved in water and applied as a substantially sediment-free solution through a boom sprayer. The liquid must be washed in immediately after application in order to avoid foliar burn and to maximise uptake by the root system.
Prilled fertilisers Fertilisers that are manufactured with a smooth, hard outer surface that enables the prills to flow freely when being spread.
Mineralisation Natural organic fertilisers such as blood and bone, synthetic organic fertilisers such as urea and soil organic matter must be mineralised into plant available ammonium form by soil bacteria and fungi. Mineralisation generally occurs within a week if the soil temperature is > 10oC.
Nitrification Following mineralisation, ammonium (NH4+) is converted to nitrite (NO2-) and then finally to plant available nitrate, (NO3-) form.
Formulations that are animal or vegetable (carbon) based including natural minerals, animal manures and waste produced from industry. These products usually have low nutrient analysis. Nutrients are generally not available for plant uptake until converted into plant available forms by soil micro organisms, i.e. mineralisation.
Plant available Nitrogen Fertilisers supply nitrogen in several different forms, but only two, the ammonium (NH4+) and nitrate (NO3-) ions, can be taken up by plants.
Salt index Fertilisers have a salt index, which indicates their potential to increase the level of salts or salinity in the soil. Fertilisers with a high salt index are more likely to burn plants when applied.
Slow release fertiliser Manufactured products that are either not totally water-soluble or are manufactured in such a way that the nutrients are released slowly from the granule. Sometimes semi-permeable (polymer) or slowly dissolvable (e.g. sulphur coated) coatings, or a combination of both technologies, are used to control nutrient release. Another approach is to alter the chemical form to produce long chain molecules that control nutrient release by either hydrolysis or microbial break down or a combination of both.
Soil conditionerA substance that is added to a fertiliser, or applied by itself, that alters the physical/structural characteristics of the soil by; altering air or water retention capacity; encouraging flocculation; discouraging compaction; increasing soil biological activity or increasing air circulation or drainage.
Solubility The solubility of a fertiliser is the measure of its ability to dissolve in water. The higher the solubility, the more rapid its release or availability to plants.
Standard (N.P.K) fertilisers Standard fertilisers are the basic nitrogen, phosphorous and potassium based formulations from which all other categories of products are derived through further processing.
Click on the following link to view table of fertilisers :- Facts Formulations and Fundalmentals of Fertilisers
You will need to rotate the table once you have opened the link.
Balance Agri-Nutrients. Nutrient handbook
Murphy, J.A. Gypsum in turf culture. AgResearch Bulletin.
Bengeyfield, W.H. (1987). The forgotten magic of lime. USGA Green Section Record
Article kindly provided by the The New Zealand Turf Managenent Journal
New Zealand Sports Turf Institute
163 Old West Road
PO Box 347