Fertilisation is a method of improving the nutritional status of the soils, and can be tailored to provide the correct nutritional requirements at the most appropriate time.
Fertilisers are food for plants; they contain plant nutrients (nourishing substances), which all plants need to grow and stay healthy.
There are 13 elements which plants take from the soil. Nitrogen (N), phosphorus (P), and potassium (K) are used in relatively large amounts. Sulphur (S), calcium (Ca), carbon (C) and magnesium (Mg) are also often required. Zinc (Zn), iron (Fe), manganese (Mn), Boron (B), copper (Cu) and molybdenum (Mo) are other elements.
The soil provides most of the nutrients needed, and shortages can be overcome by using carefully chosen fertilisers. It would be wasteful to apply a nutrient if your soil already has sufficient.
In general, macro elements such as nitrogen (N), phosphate (P) and potassium (K) are the nutrients most likely added to the soil.
|Photo used courtesy of Helen Gordon, WWF SA|
|Nitrogen (N)||Applying nitrogen (N) improves overall crop quality. It helps plants develop the green colour they need to take food from the sun, and to take the necessary food from the soil. N increases the number of branches, leaves, seeds and fruits, and accelerates the number of plant cells in the plant. A shortage of nitrogen will result in yellow leaves and poor plant growth.|
|Phosphorous (P)||Adding phosphorous (P) to the soil leads to better root development, helps with grain and seed development. Plants are assisted to ripen early and mature quickly.|
|Potassium (K)||The addition of potassium (K) to the soil improves crop yields and quality, strengthens plants and helps them resist drought and disease. It helps the plant to breathe and plays a major role in the plant’s use of water (stomata) and its build up of starches, sugars, fats and protein.|
Although NPK volumes are the highest, it is of utmost importance to emphasise the necessity of all other elements too.
|Magnesium (Mg)||Magnesium (Mg) helps plants to breathe and phosphorous to get into the plant. Mg is a vital element in photosynthesis. Too much will slow down the plant’s ability to absorb potassium.|
|Calcium (Ca)||Calcium (Ca) forms the ‘building blocks’ in plant cells which ensure firmness, shelf life and quality produce. Calcium (Ca) strengthens plants and reduces/neutralises toxicity in the soil.|
|Sulphur (S)||Sulphur (S) is essential for uptake of Nitrogen (N). S helps in leaf development and increases the quality of grain and fruit. It is responsible for flavour attributes in crops such as onions and garlic.|
|Zinc (Zn)||A key constituent of many enzymes and proteins|
“Straight” and “multi-nutrient” fertilisers
Fertilisers are either “straight” or “multi-nutrient”. Straight fertilisers are products containing one of the main plant nutrients. Some examples are given below:
Calcium ammonium nitrate (CAN)
Limestone ammonium nitrate (LAN )
|Phosphate (P)||Single superphosphate (SSP)|
Triple superphosphate (TSP)
|Potassium (K)||Muriate of potash (MOP)|
P and K are shortened forms: P = P2O5 x 0.44 and K = K2O x 0.83
Multi-nutrient fertilisers contain more than one of the main plant nutrients. There are figures (numbers) printed on a fertiliser bag which will give you the ratios of plant nutrients of that fertiliser. They always follow the same sequence. The first number is the ratio of N, the second is the ratio of P, and the third refers to the ratio of K. Divide the figure given in the ration by 9, and then multiply it by 30. So 3.2.4. (30), for example, means that the fertiliser contains 10% of N, 6.6% of P and 13% of K.
(The above information is taken from the Fertiliser Retailing Guide, put out by the Food and Agriculture Organisation of the United Nations, the Fertiliser Industry Advisory Committee; and Omnia and Yara Specialities).
The ‘Law of the minimum’ illustrated by barrel staves of varying lengths represent growth-controlling factors. This is also known as Liebig’s law. The barrel story illustrates that success will be limited / handicapped by that element which is deficient. If only one element lacks in availability or is inadequate in supply one will not achieve optimum results. This is why a comprehensive nutrient programme or “balanced diet” is important.
What is the effect of water on fertiliser in the soil?
Water dissolves the fertiliser. The nutrients are carried by the soil water to the roots of the plant. If there is not enough water in the soil, the nutrients cannot reach the roots of the plant, nor can they be absorbed by the plant.
Can a farmer apply too much fertiliser?
Excessive fertiliser use can damage crops and reduce yields. It contributes to pollution of soil and ground water. Apart from also being a waste of money, it damages the overall image of agriculture when it comes to looking after the environment.
How do I know how much fertiliser to apply?
This depends on soil and crop. Clay soil, for example, requires a totally different application to sandy soil. If you want to know what fertiliser you need and how much to apply to your soil, take a soil sample from your land or a leaf sample from one of your crop plants and have it tested at an agricultural laboratory or a place where soil can be analysed to show which nutrients are lacking. These places can give a fertiliser recommendation. This money will be well spent because it can save you thousands later.
When is the time to apply fertiliser?
If fertiliser is applied at the wrong time, the yields will be lower and the farmer will make less money. The “basal” dressing should generally be applied at planting, and the “top” dressing should usually be completed before the plant flowers.
Best Fertiliser Practice
Over fertilising or under fertilising will affect your profit – too much will increase your costs and be bad for the environment; not putting enough fertiliser on will decrease the yield and thus your income. Two factors will assist you:
- A soil analysis is crucial. Take a soil sample, representative of the field (don’t just take the sample from one place). The interpretation of the analysis must be soil and crop specific.
- Determine the target yield.
Liming must by no means be neglected. Too much acid in the soil:
- decreases the availability of phosphorus
- inhibits the efficient uptake and use of both water and fertilizer
- renders applied herbicides insufficient
- suppresses the effectivity of micro-organisms in the soil
Under highly acidic conditions it can, from an economic point of view, even be more beneficial to lime instead of increasing the fertiliser application rate.
The biological life in the soil was neglected in the past. The value of micro-organisms in soil mustn’t be underestimated. The positive influence of a well balanced, healthy microorganism population on the availability of plant nutrients has been well proven. Experts are available to advise farmers accordingly.
Do not neglect the biological life in the soil. A healthy micro-organism population make more plant nutrients available – a great benefit. Experts are available to advise you.
Compare the pros and cons of the different products. More concentrated products can reduce costs (there is less to transport), but in general do not contain the same amount of secondary elements.
Although band placement of fertiliser is generally the most effective, there is a place and time for broadcast application and foliar sprays. The method of fertiliser application has a definite effect on fertiliser efficiency.
This ensures that the whole field is fertilised according to the soil analysis and expected yield. Money is saved, yields are increased and risk is reduced.
Determine the water content of every field. If there is not enough, then plant less or don’t plant at all. Effective weed control is important since water and plant nutrients are consumed by weeds. Effective soil cultivation allows more water (and fertiliser) to infiltrate the soil.
Plant sap analysis
Taking regular plant sap samples will help you to address nutrient deficiencies in time. They will also prevent unnecessary fertiliser being applied.
Source: adapted from the article “Best Fertilizer Practices” which appeared in Volume 14 of The FarmAfrica
International business environment
The South African industry’s margins are determined largely by world market prices of major raw materials, while domestic prices are primarily driven by import parity cost of commonly traded fertiliser commodities.
The main fertiliser consumers in Africa include Egypt, South Africa and Morocco. Total fertiliser consumption in sub-Saharan countries is approximately 1% of the world fertiliser consumption. On average these farmers use 8-10 kg/ha of nutrients which is only 10% of the world average. More nutrients are removed from the soil annually, mainly through harvesting of crops, than are being returned to the soil.
Read about the African Fertilizer and Agribusiness Partnership (AFAP) at www.afap-partnership.org. Its East and Southern Africa Fertilizer Trade Platform (ESAF) is designed “to facilitate and co-ordinate enhanced private sector investment and participation in the procurement and distribution of fertilizer in the region”. The South African headquarters in Rivonia can be contacted at 011 844 7320, or by writing to info [at] afap-partnership.org.
View the following websites:
- www.agindustries.org.uk – Agricultural Industries Confederation (UK)
- www.efma.org – Earth Fertiliser Manufacturers
- http://fertilizerseurope.com – Fertilizers Europe
- www.ifdc.org – International Fertiliser Development Centre
- www.fertilizer.org – International Fertiliser Association
- www.ipipotash.org – International Potash Institute
- www.ipni.net – International Plant Nutrition Institute
- www.fertiliser-society.org – The International Fertiliser Society
- www.sulphurinstitute.org – The Sulphur Institute
Local business environmentwww.fertasastats.co.za provides trade statistics. The various presentations under “Events” at www.fertasa.co.za are also a source of useful information.
The industry supplies around 2 million tons of fertiliser products to the local market annually at a value of around R10 billion. In South Africa the maize industry consumes between 40% and 50% of all fertilisers and the market, therefore, is much influenced by what happens to this industry.
The absence of urea production facilities and sources of potash in South Africa is another reason for high levels of imports (Urea and Potassium Chloride make up the bulk of imported product). South Africa is a net importer of fertiliser products excluding ammonia and rock phosphate.
Nearly two-thirds of South Africa’s fertiliser exports are to Zambia and Zimbabwe. Other destinations include Botswana, Mozambique, Australia, Brazil, Malawi, Swaziland, Angola, Democratic Republic of the Congo and Kenya.
Negatives for the fertiliser industry include a land reform policy where it takes some time for new farmers to be fully established as commercial farmers, and if farmers were discouraged from planting maize and went instead for crops which use less fertiliser than maize. The emergence of a biofuel industry would be a positive for the industry as the crop demand would impact favourably on the need for fertiliser.
National strategy and government contact
The “Legislation & regulations” option at www.fertasa.co.za is of great help here. It sets out the fertiliser regulations, registration documentation and contacts at the Department of Agriculture, Forestry and Fisheries (DAFF). The reader can also find information by looking for the “Agriculture Inputs Control” option under “Branches” at www.daff.gov.za.
The Agricultural Policy Action Plan (APAP) notes that since 1999 South Africa’s domestic use of fertiliser has relied increasingly on imports (true also for other inputs like diesel, machinery and ingredients for animal feeds). It calls for more sustainable production systems and a revitilisation of the local fertiliser industry.
The Fertilisers, Farm Feeds, Agricultural Remedies And Stock Remedies Act, 1947 (Act No. 36 of 1947) provides for:
- the appointment of a Registrar of Fertilisers, Farm Feeds, Agricultural Remedies and Stock Remedies;
- the registration of fertilisers, farm feeds, agricultural remedies, stock remedies, sterilising plants and pest control operators;
- to regulate or prohibit the importation, sale, acquisition, disposal or use of fertilisers, farm feeds, agricultural remedies and stock remedies;
- the designation of technical advisers and analysts.
The main provisions of Act No 36 of 1947 are: control over the registration of fertilisers, farm feeds, agricultural remedies, stock remedies, sterilising plants and pest control operators; to regulate or prohibit the importation, sale, acquisition or disposal of these inputs. This Act applies where a person imports, sells, acquires or disposes the mentioned articles. It is therefore advisable to be aware of these requirements. The Act is currently being revised and a Fertiliser Bill is out for public comment (March 2019). Keep your eyes on the “Legislation & Regulations” option at www.fertasa.co.za.
- Fertilizer Society of Southern Africa (Fertasa) Tel: 012 349 1450 www.fertasa.co.za Fertasa, a non-profit company, represents the interests of the fertiliser and aglime industries in South Africa.
- IZASA (International Zinc Association of Southern Africa) Tel: 083 456 4989 www.izasa.org
Training and research
- The Agricultural Research Council campuses periodically do fertiliser-related research.
- Fertiliser Advisors, Certification and Training Scheme (FACTS), a fertiliser advisors’ training course, administered by the Fertasa, is aimed at improving the skills of fertiliser advisors. Candidates are drawn from private sector, government, agri-business and co-operatives in South Africa and from neighbouring countries. For more information on the course contact Gisela Deysel by calling 076 672 3793 or emailing gisela [at] basos.co.za.
- Fertiliser companies conduct in-house training and research within their own Research and Development departments.
- Find universities, agricultural colleges and other role player details in the “Agricultural education and training” chapter. One example: The Unit for Environmental Sciences and Management at North-West University in Potchefstroom does research on soils and can help with fertiliser recommendations and precision farming. Call PW van Deventer at 018 285 2267 or write to him at 10058591 [at] nwu.ac.za.
Find details of all Fertasa members at www.fertasa.co.za. Fertasa members below are indicated with the symbol √.
See the “Speciality fertilisers” chapter for a full list of role players. Presentations on biofertilisers (Fertasa Biofertilizer Workshop, November 2017) can be found under “Events” at www.fertasa.co.za.
- Agrilibrium√ Tel: 021 553 4867 www.agrilibrium.co.za
- Ecologika Tel: 011 806 8700 www.ecologika.co.za
- Metson Manufacturing√ Tel : 011 792 8968 www.metson.co.za
- Nulandis√ Tel: 011 823 8000 www.nulandis.com
- Nutrico SA√ Tel: 011 392 4072 www.nutrico.co.za
Mineral fertiliser and/or mineral fertiliser ingredients
- Advanced Agri Tel: 060 624 4049 http://advancedagri.co.za
- Afrifert Tel: 013 261 2640 / 058 303 1348 www.ovk.co.za
- Aquasol Nutri√ Tel: 018 294 8901/2 http://aquasolgroup.com
- ArcelorMittal√ Tel: 016 889 9111 / 9575 www.arcelormittalsa.com
- Constantia Fertiliser Tel: 017 826 4118 www.twkagri.com/constantia-fertilizer
- Dfert Tel: 056 515 4100 www.dfert.co.za
- Experse√ Tel: 011 409 5000/56 www.experse.com
- Foskor√ Tel: 011 347 0600 www.foskor.co.za
- Gavilon√ Tel: 011 367 8420 www.gavilon.com
- Industrial Commodities Holdings√ Tel: 011 880 5200 www.ich.co.za
- Innofert√ Tel: 011 300 8640 www.innofert.co.za
- Kimleigh Chemicals√ Tel: 018 293 1028 www.kimleigh.co.za
Organic fertiliser producers
See also the “Compost & organic fertiliser” chapter.
- Atlas Organic Fertilisers√ Tel: 078 451 8988 www.atlasorganies.co.za
- Cape Lime Tel: 027 213 3090 www.capelime.co.za
- Eco-Green Agri Tel: 021 871 1303 https://ecogreenagri.com
- Geysers Tel: 031 207 6763 http://rossmin.co.za
- Grasland Ondernemings√ Tel: 018 632 6046 http://grasland.co.za
- H Pistorius & Kie√ Tel: 012 342 1075 www.kalk.co.za
- Kalkor√ Tel: 011 721 3141 www.kalkor.co.za
- Limecor√ Tel: 012 664 9770 www.limecor.co.za
- P&B Lime Works Tel: 028 424 1157 www.pandblime.co.za
- SA Lime & Gypsum Tel: 0860 103 515 www.sakg.co.za
- Kynoch Tel : 011 317 2000 www.kynoch.co.za
- Liquigro Holdings Tel: +27 (0)21 535 5331 www.liquigro.co.za
- NWK Group√ Tel: 018 633 1000 www.nwk.co.za
- Omnia Fertilizer√ Tel: 011 709 8888 www.fertilizer.co.za
- Plaaslike Boeredienste Tel: 016 986 0691
- Profert√ Tel: 018 293 3530 www.profert.co.za
- Sasol Base Chemicals√ Tel: +27 (0)11 441 3111 www.sasol.com
- Sabic√ Tel: 021 409 6100 www.sabic.com
- Seakor Zn Fert√ Tel: 011 422 2832 https://seakor.co.za
- Sidi Parani√ Tel: 053 298 2817 www.sidiparani.co.za
- Triomf√ Tel: 0861TRIOMF / 018 285 1291 www.triomfsa.co.za
- Westfert Tel: 053 444 1936 www.westfert.com
- Zinchem√ Tel: 011 746 5000 www.multimikro.co.za
Other role players
- DFM Software Tel: 021 904 1154 www.dfmsoftware.co.za Software to identify fertiliser needs and effectiveness
- Electrolee Tel: 012 345 3193 www.electrolee.co.za Optimise your fertilising practices
- JP Lamberg & Associates 035 753 4734
- NviroTek Labs Tel: 082 885 8699 www.nviroteklabs.co.za Independent analysis of soil, water, plants, fertiliser, lime and feed
Websites and publications
Visit the websites listed earlier in this chapter.
The following publications are available from Fertasa:
- Fertilizer Handbook (also available in Afrikaans). This is a hard cover handbook that has primarily been written for the use of persons who are involved in some way or another in a fertiliser advisory capacity. It is not intended to be a complete technical handbook, but rather a concise presentation covering a wide range of topics. For this reason, interested farmers and students will also find it to be a useful guide. It is prescribed as part of the agricultural curriculum at some universities and universities of technology in South Africa.
- Deficiency Symptoms in Maize. A4-size colour pamphlet depicting the deficiency symptoms in maize.
- Plantfood & Fertilizers. Illustrated publications for the emerging farmer. A4-size, in ring-binder format.
- Soil Acidity and Agricultural Lime (also available in Afrikaans as Grondsuurheid & Landboukalk). This brochure contains the two chapter “Soil acidity” and “Agricultural lime” which appear in the Fertilizer Handbook. This brochure is intended as a general guide for agronomists and farmers alike who have a common purpose in sound liming.
- Soil Fertility. Illustrated publications for the emerging farmer. A4-size, in ring-binder format.
- Fertasa Journal – a publication containing the proceedings of the Fertasa annual congress
- The Proceedings of previous Symposiums
Visit www.kejafa.com for the following publications from Kejafa:
- Bemesting Fertilizer
- Sea Energy Agriculture
- Fertility from the ocean deep
- Fertilizer Handbook
The ARC‘s excellent Maize Information Guide (MIG) includes notes on fertilisation. Download it from www.arc.agric.za.
Find the “Kunsmis” option at the Landbouweekblad website, www.landbou.com.
Take a look at the annual South African fertiliser market analysis report on the Directorate Marketing pages on the Department of Agriculture, Forestry and Fisheries website, www.daff.gov.za. On the same website, find the Info Paks (take the “Resource Centre” option) that deal with soil. These include “Soil: acid soil and lime” and “Soil: application of lime”.
The videos at SA Orchard include ones which look at fertilisation and the micro elements. See www.saorchard.co.za.
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