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All plants need certain mineral elements for proper growth, development, and maintenance. The basic structure of all organisms is built of carbon (C), oxygen (O) and hydrogen (H). Plants obtain these elements from water (H2O) in the soil and carbon dioxide (CO2) in the air, so no input is required beyond being sure the plant has an adequate water supply to meet its needs. Turning the H2O and CO2 into organic building blocks, however, is a complex process that requires the assistance of at least 13 other elements.

Three elements, nitrogen (N), phosphorus (P), and potassium (K), are required in relatively large quantities and are referred to as primary or macronutrients. N is an important component of all protein, so is integral to the plant structure. P is a minor component of protein, but is integral to the molecules that control energy flow within the plant and is a component of genetic material. The role of K seems to be in maintaining the correct salt concentration in the plant sap. N, P, and K, in varying ratios, are the primary constituents of all chemical fertilizers. Depending on the fertilizer origin, their amounts present may be expressed as N, P2O5, and K2O.



  1. Ressource principale
    20/01/2009 All plants need certain mineral elements for proper growth, development, and maintenance. The basic structure of all organisms is built of carbon (C), oxygen (O) and hydrogen (H). Plants obtain these elements from water (H2O) in the soil and carbon dioxide (CO2) in the air, so no input is...
  2. AccessAgriculture Training Video Dans cette vidéo vous apprendrez tout ce qu’il faut savoir sur les nutriments, la structure des sols, la matière organique et les moyens de maintenir la fertilité du sol. Ceci vous permettra de continuer à cultiver votre terre en produisant des cultures saines....
  3. This section looks at the way in which soil quality can be maintained and improved through a number of techniques including the use of fertilizer, manure and compost.
  4. 08/02/2017 Cover crops play a key role in sustainable agriculture by providing sustainable sources of nutrients as well as protective soil cover to minimize erosion and reduce moisture stresses. Examples of successful cover cropping systems in East Africa will be illustrated as well as constraints and...
  5. 20/04/2020 The source documents (.docx and .pub)of these materials are available in the author's dropbox. The source documents are updated periodically so check here for the most current formats. We encourage you to adapt the source for your purposes. Learning Outcomes – Participants will: 1. Understand the...
  6. Abstract, Makerere University Dissertations, 2019 Low crop yields due to low erratic rainfall, high evapo-transpiration, and deteriorating soil fertility in semi-arid areas of the country, have led to a quest for sustainable production practices with greater resource use efficiency in order...
  7. 20/07/2005 Joel Matthewsreceived some feedbackabout his comments on low fertility soil and traditional varieties in EDN 86. In response, he sent the following additional comment.
  8. 20/01/2002 The conventional view of the relationship between soil nutrients and crop productivity in the tropics is leading to both damaging agricultural policies and inefficient and damaging farm-level practices. There is no need to use the huge quantities of chemical fertilizers that are so often...
  9. 12/02/2019 Session: Ken’s research focuses on smallholder farming systems in sub-Saharan Africa, and in particular problems of soil fertility with emphasis on nitrogen fixation by legumes and the temporal and spatial dynamics of resources within crop/livestock farming systems. Biographical information: Ken...
  10. Small holder farmers and practitioners from Tanzania share agroecology best practices to improve soil fertility. English Subtitles
  11. 20/04/2013 An important principle of conservationagriculture is that of targeted, precision applications of organic or inorganic fertilizer near crop plants, as opposed to evenly dispersing inputs over an entire field. In a row-crop setting, this can be done by banding fertilizer next to the crop plants. In...
  12. AccessAgriculture Training Video Une vidéo de 22 minutes pour expliquer l'importance de combiner des ressources organiques, des engrais minéraux et des variétés améliorées de manière adaptée aux conditions locales. Des cas pratiques tirés de diverses zones agro-écologiques du Mali, Niger,...
  13. 20/12/2012
  14. 20/11/2019 Swahili Only
  15. 20/01/2005 Maradi Integrated Development Project has forced me to question the wisdom of assuming that increases of organic content and fertility are always best.
  16. 20/01/2011
  17. 06/02/2018 Speaker Bio: Dr. Tom Thompson is Associate Dean and Director of International Programs in the College of Agriculture and Life Sciences and Professor of Agronomy at Virginia Tech. He earned B.S. , M.S. , and Ph.D. degrees in agronomy and soil science. He was an academic department head at two...
  18. Session:Ken’s research focuses on smallholder farming systems in sub-Saharan Africa, and in particular problems of soil fertilitywith emphasis on nitrogen fixation by legumes and the temporal and spatial dynamics of resources within crop/livestock farming systems. Biographical information:Ken...
  19. 04/10/2017 It is often a problem in tropical soils farmed by smallholders that the soil is nutrient-depleted and acidic, costing the farmer more money and yielding less valuable crops. In an attempt to overcome this, Dr. Tom will discuss different ways of evaluating important soil properties and thus...
  20. En observant les feuilles de maïs, on peut diagnostiquer quatre carences en éléments nutritifs - phosphore, potassium, azote et magnésium. Ce document comprend des photos d'une feuille de maïs en bonne santé et de feuilles de maïs démontrant chacune de ces carences en éléments nutritifs. Il...
  21. 16/02/2015 Every February-March, rice fields are burned throughout Thailand. These very low temperature burns produce huge amounts of smoke that causes serious public health problems, as well as greenhouse gases, smog precursors, dioxin and furans. This practice also destroys valuable organic matter...
  22. 03/10/2017 Soils of smallholder farmers are often depleted of organic matter and available soil nutrients, and may also be acidic and/or saline. We will review the causes and extent of these soil-related challenges in the developing world. A variety of possible management responses to these challenges will...
  23. 06/02/2018 Speaker Bio: Dr. Tom Thompson is Associate Dean and Director of International Programs in the College of Agriculture and Life Sciences and Professor of Agronomy at Virginia Tech. He earned B.S. , M.S. , and Ph.D. degrees in agronomy and soil science. He was an academic department head at two...

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