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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. ทรัพยากรหลัก
    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. 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.
  3. 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...
  4. 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...
  5. 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...
  6. 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.
  7. 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...
  8. 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...
  9. Small holder farmers and practitioners from Tanzania share agroecology best practices to improve soil fertility. English Subtitles
  10. 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...
  11. 20-12-2012
  12. 20-11-2019 Swahili Only
  13. 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.
  14. 20-01-2011
  15. 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...
  16. 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...
  17. 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...
  18. Four nutrient deficiencies--phosphorus, potassium, nitrogen, and magnesium--can be diagnosed by observing maize leaves. This document includes photos of a healthy maize leaf and of maize leaves demonstrating each of these nutrient deficiencies. It also contains suggestions for how to address each...
  19. 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...
  20. 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...
  21. 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...
  22. Access Agriculture Training Video The main aim is to reduce costs and improve profitability. Soil health is improved as is soil moisture. Zambia is leading the way in Sub-Saharan Africa and this programme shows how the technique is practised. Available languages Arabic Bambara Burmese English...
  23. Access Agriculture Training Video For healthy crops you need a healthy soil, because a healthy soil contains many good microbes and earthworms. To prepare biofertilizer for half a hectare, you need 10 kg fresh cow dung, cow urine, flour from chickpeas or another pulse, jaggery or unrefined sugar,...
  24. Access Agriculture Training Video Vermiwash is the liquid that is collected after water passes through compost made by earthworms. It is rich in plant growth hormones, micro-nutrients, and major nutrients like nitrogen, phosphorous and potassium. Available languages Arabic Bambara Bariba Bemba...
  25. Access Agriculture Training Video Introduction to sustainable land management practices which have a proven track record in Africa. They can help control land degradation and improve production for small scale farmers, despite the challenges of climate change. Available languages Bemba Chitonga...
  26. Access Agriculture Training Video Integrated soil fertility management is based on maximising the use of organic fertilizers and minimizing the loss of nutrients. Available languages Bemba Chichewa / Nyanja Chitonga / Tonga English French Kiswahili Spanish Tumbuka

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