Differences between mixed fertilisers and complex fertilisers

Transcription

1 Differences between mixed fertilisers and complex fertilisers Inorganic, complex, mixed, liquid and pure fertilisers, and the composition of them Henning Lyngsø FOGED (MSc Agriculture), enagro, Denmark

2 2 Purpose of the presentation Terminology of fertilisers according EU s Fertiliser Regulation Production of inorganic fertilisers Definition of inorganic fertilisers and sub-types Presentation of inorganic fertilisers and examples of their chemical composition Differences between complex and mixed fertilisers

3 3 Terminology Those with a green border are defined in EU s Fertiliser Regulation, while the others generally are popular terms Chelated fertiliser Inorganic fertiliser

4 4 Inorganic fertiliser types Many soils require the addition of several essential nutrients to alleviate plant deficiencies. Farmers may have the option of selecting a combination of single-nutrient fertilisers or using a fertiliser that has several nutrients combined into each particle. These combination (compound or complex) fertilizers can offer advantages of convenience in the field, economic savings, and ease in meeting crop nutritional needs.

5 5 Terminology - grouped Fertilisers on liquid form and the way the nutrients are blended Inorganic fertiliser Compound fertiliser Fluid fertiliser Mineral fertiliser Straight fertiliser Suspension fertiliser Artificial fertiliser Complex fertiliser Solution fertiliser More or less synonyms Chemical fertiliser Blended fertiliser Mixed fertiliser* Liquid fertiliser Terms that relates to the number of plant nutrients the fertiliser contains and how it is produced. Unless otherwise stated, on solid form. Pure fertiliser Complete fertiliser Terms that are used to explain the way the fertiliser works Foliar fertiliser* Slow release fertiliser Start fertiliser * Can also be organic

6 6 Inorganic fertilisers raw material Production price depends on energy prices Inorganic fertiliser raw materials are also called primary fertilisers: Nitrogen are via the Haber-Bosch process extracted from the atmosphere and fixated in the form of ammonia. Ammonia can further react with nitric acid and become ammonia nitrate. Phosphorus comes from phosphate rock, it is treated with sulfuric acid, producing phosphoric acid. Some of this material is reacted further with sulfuric acid and nitric acid to produce a triple superphosphate, an excellent source of phosphorous in solid form. Some of the phosphoric acid is also reacted with ammonia in a separate tank. This reaction results in ammonium phosphate, another good primary fertilizer. Potassium chloride is extracted from minerals sylvite, carnallite, and potash. It is also extracted from salt water and can be manufactured by crystallization from solution, flotation or electrostatic separation from suitable minerals. It is a by-product of the production of nitric acid from potassium nitrate and hydrochloric acid. The manufacturer converts it into a more usable form by granulating it. This makes it easier to mix with other fertilizer components in the next step. Micro nutrients are typically mined.

7 7 Inorganic fertilisers raw material Inorganic fertiliser production explained in simplicity Fertilisers, Cairo 26-27/

8 8 Chemical composition of primary fertilisers Type Formula N, % P 2 O 5, % K 2 O, % Ammonia* NH 3 82 Ammonium nitrate* (NH 4 )(NO 3 ) 35 Triple superphosphate* Ca(H 2 PO 4 ) 2 H 2 O 45 Ammonium phosphate (NH₄)₃PO₄ Potassium chloride* KCl 52 * Pure = straight = simple = single nutrient fertilisers

9 9 Examples of other pure fertilisers N, % P 2 O 5, % K 2 O, % Urea 46 Ammonia sulphate 21 Prilled ammonium nitrate 34 Ammonium nitrate / calcium carbonate Superphosphate Potassium sulphate 52

10 10 Comments on primary and pure fertilisers Representative sampling is easy it is uniform products The price of the nutrients are relatively low due to the low level of processing They are costly to use, because the application of NPK to a field must be done in at least three operations, and each operation takes time, costs money (diesel, machinery depreciation and maintenance), and driving on the field with machinery leads to compaction of the soil. The dosing can happen exactly so they comply with the norms

11 11 Fertilising example with pure fertilisers compared to complex fertilisers 1 ha wheat Kg N P 2 O 5 K 2 O Norm, kg per ha ha wheat Kg N P 2 O 5 K 2 O Norm, kg per ha Ammonium nitrate Triple superphosphate Potassium chloride NPK Balance Balance What is best???

12 Mixed and complex / compound fertilisers 12 are artificial fertilisers, which is the same as mineral fertilisers. They are often complete fertilisers, containing all three main plant nutrients, N, P and K. They are typically solid fertilisers on a granular form, spread with a disc spreader like shown here.

13 13 Mixed fertilisers A mixture of two more straight fertiliser materials is referred to as fertiliser mixture. Sometimes, complex utilises containing two plant nutrients are also used in formulating fertiliser mixtures. Complete fertiliser refers to the fertilisers containing three major plant nutrients, N, P2O5 and K2O. Mixed fertilisers are also called "Blended fertiliser, meaning a fertiliser obtained by dry mixing of several fertilisers, with no chemical reaction.

14 14 Mixed fertilisers If the mixed fertilisers are of different granule size or density, the risk is that the nutrients by spreading are unevenly distributed on the field, because the largest and heaviest granules tends to fly longest, while dust and small granules dumps down shortly behind the spreader and is taken by the wind.

15 15 The largest granules are flying longest

16 16 Mixing fertilisers

17 17 Mixed or complex the difference is visible Mixed fertiliser Complex fertiliser

18 18 Changes that occur while manufacturing mixed fertiliser The ingredients used in fertiliser mixtures vary widely in their physical and chemical characteristics. When such widely varying materials in physical and chemical properties are mixed together, naturally many changes are expected to take place during or after the mixing. Some changes will be of physical nature and some will be of chemical nature. The following are the most important physical changes that will take place during or after the mixing of fertilisers.

19 19 Changes that occur while manufacturing mixed fertiliser Hygroscopicity It is a property of any substance which absorbs from air and gets converted to semi-solid or liquid condition. Fertilisers like Ca(NO 3 ) 2, NH 4 NO 3 and NaNO 3 are capable of absorbing moisture from air and become hygroscopic. In such cases handling will be very difficult for such mixtures. Caking up Moisture present in some of the ingredients is responsible for caking up. Moisture dissolves some of the easily soluble ingredients and forms a saturated solution. This saturated solution on evaporation gives out crystals which knit together forming larger lumps. The caking up can be prevented by the use of certain kind of materials called as conditioners. The commonly used conditioners are groundnut hulls, lime, clay etc. Another was of preventing the caking up is manufacture of granulated fertiliser mixture. The granulation aims at preparation of uniform sized particles with reasonable stability, which presents caking up.

20 20 Changes that occur while manufacturing mixed fertiliser Segregation This relates to separation of different sized particles individually. When ingredients of different sizes and densities are included there will be the tendency for the segregation (sorting out to different sizes) to take place. The following are some of the most important chemical changes that take place either during or after the manufacture of fertilizers mixtures. These changes are found to be influenced by temperature, moisture content and particle size of the in gradients: a. Double decomposition: The reaction is between two compounds without a common ion in the presence of moisture. New compounds are formed which may have different physical and chemical properties. b. Neutralization: This reaction takes place when free acids present in some of the fertilisers are neutralised by alkalis or Ca containing salts included in the mixture c. Hydration: The process of tying up of water by the anhydrous form of salts is called hydration. Some of the fertilisers are found to have this property. d. Decomposition: Under certain conditions of moisture and temperature, there will be break down in the composition of molecules forming new compounds.

21 21 Changes that occur while manufacturing mixed fertiliser The following important principles must be taken into consideration while preparing mixed fertilisers. 1. All fertilizers containing ammonia are not mixed directly with the alkali fertilisers (e.g. rock phosphate and limestone) as reaction will take place resulting in the loss of gaseous NH The water soluble phosphates are not mixed with those materials which contain free lime (e.g.) lime stone, CaCN 2 ) as there will be reaction towards the reversing of water soluble phosphate to water insoluble phosphates. 3. Hygroscopic fertilisers are not included as they will facilitate caking up. 4. The acidic fertilisers are likely to produce some free acids which may damage the container or packing materials.

22 22 With other words: mixing fertilisers is not for amateurs However, if blended / mixed fertilisers are marketed, they shall according the EU Fertilisers Regulation be marked as such, and they must be blended in a way so that no chemical reaction takes place after the blending. Ammonia nitrate is explosive!

23 23 Mixed fertilisers - advantages Mixed fertilisers allow to design the fertiliser exactly to the need of each crop/field, so that Each nutrient is in balance with the norm (but it does seldom happen in practice) One field application is enough saves time and money

24 24 Complex fertilisers Complex fertilizers - are fertilizers during the production of which a chemical reaction occurs among the components which react reciprocally, whereby a homogenous product of uniform composition is created, representing certain chemical compounds. They may also be produced with elements that provide some of the lesscommon plant nutrients (known as secondary or trace nutrients, such as sulphur, calcium and magnesium). Compound fertiliser can be packaged and distributed in liquid or granular form. A numbering system is used to define the percentages of the three essential plant nutrients. For example, a fertilizer would contain 20 percent nitrogen, 20 percent phosphorus and 10 percent potassium. Secondary nutrients and trace elements are typically listed.

25 25 Complex fertilisers Example of complex fertilisers in a granular form

26 26 Complex fertilisers Complex fertilisers are made using basic fertiliser materials, such as NH 3, ammonium phosphate, urea, S, and K salts. There are many methods used for making these fertilisers, with the specific manufacturing processes determined by the available basic components and the desired nutrient content of the finished product. Here are three brief examples. Compaction methods (agglomeration) involve binding small fertiliser particles together using compaction, a cementing agent, or a chemical bond. Various nutrient ratios can be combined using undersized particles that may not be suitable for other applications. Accretion-based fertilisers are made by repeatedly adding a thin film of nutrient slurry which is continually dried, building up multiple layers until the desired granule size is reached. Pipe-cross reactors are used to chemically melt NH 3, acids containing S or P, and other nutrients such as K sources and micronutrients into a solid fertiliser with the desired nutrient content.

27 27 Complex fertilisers Complex fertilisers contains multiple nutrients in each individual granule. This differs from a blend of fertilisers mixed together to achieve a desired average nutrient composition. This difference allows complex fertilizer to be spread so that each granule delivers a mixture of nutrients as it dissolves in the soil and eliminates the potential for segregation of nutrient sources during transport or application. A uniform distribution of micronutrients throughout the root-zone can be achieved when included in complex fertilisers. These fertilisers are especially effective for applying an initial nutrient dose in advance of planting. There are certain ratios of nutrients available from a fertiliser dealer for specific soil and crop conditions. This approach offers advantages of simplicity in making complex fertiliser decisions, but does not allow the flexibility to blend fertilisers to meet specific crop requirements. Turf managers and homeowners often find complex fertilisers desirable.

28 28 Examples of complex fertilisers Complete fertilisers Complex fertilisers with two nutrients / binary Liquid, foliar fertilisers N, % P 2 O 5, % K 2 O, % Mg, % S, % Ca, % Na, % Mn B Zn Fe Cu Mo NPK NPK DAP NP NP Basfoliar FoliQ MikroMax

29 29 Liquid fertilisers 90% of all fertilisers used globally are solid, and 10% liquid; Liquid fertilisers are said to have a quick effect, and it is logically given to growing crops, often in the stage of peak growth. Liquid fertilizers comprise anhydrous ammonia, aqueous solutions of ammonia, aqueous solutions of ammonium nitrate or urea Liquid fertilisers can roughly be divided into Conventional complex fertilisers of solution or suspension type these fertilisers are spread on the crops via irrigation systems, and the operation called fertigation; Foliar fertilisers are applied directly to leaves. The method is almost invariably used to apply water-soluble straight nitrogen fertilisers and used especially for high value crops such as fruits. Some foliar fertilisers contain chelated micronutrients;

30 30 Liquid fertilisers UAN is an abbreviation for urea and ammonium nitrate. It is a solution of urea and ammonium nitrate in water. The table shows different grades of the UAN fertiliser.

31 31 Foliar fertilisers Foliar fertilisers may be spread with a field sprayer, and in some cases even sprayed out in a mixture with pesticides, provided the mix is compatible.

32 32 Ways of storing liquid fertilisers

33 33 Liquid fertilisers From a dealers homepage. As seen, also sold in small canisters for garden owners. Examples of the formulation is seen

34 34 Liquid fertilisers Liquid fertilisers are generally easy to sample in a representative way. However, segregation can have taken place in case the nutrients are included in a suspension.

35 35 Liquid fertilisers Example of a fertiliser that can be described as based on waste, in this case fish waste; Organic; Liquid; Not all nutrient N is soluble, meaning part of it is suspended, and this is also why it is recommended to stir well before using - the same shall be done before sampling;

36 36 Summing up on differences on complex, mixed and other inorganic fertilisers This presentation has provided information about Terminology of fertilisers, and a presentation of the way inorganic fertilisers are produced; There are for fertilisers used many terms with more or less identical meaning. EU s fertiliser regulation provides a legal definition of the terms in EU. All inorganic fertilisers are made of the same primary fertilisers; N and K production is based on energy consumption, while P and most micronutrients are mined. Primary and pure fertilisers can be applied completely in accordance with the norms, but are typically to costly to spread, wherefore farmers have an interest to use fertilisers with a combination of nutrients, here under binary and complete fertilisers. Mixed fertilisers; Mixed fertilisers are relatively cheap but has many disadvantages, such as a requirement to avoid unwanted chemical reactions and segregation, being a challenge also for representative sampling. Complex fertilisers; Complex fertilisers are easy to use (and to sample), but they are more expensive and it is in fertilisation almost impossible to avoid imbalances of nutrients. Liquid fertilisers; Liquid fertilisers, here under foliar fertilisers are not used much, and the use is typically for high value productions, such as flowers and fruit plantations

37 37 Contact Henning L. Foged Mobile