Plant Nutrition

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Plant Nutrition
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Macronutrients  

• Macronutrients can be broken into two more
  groups  primary and secondary nutrients. 
  The primary nutrients are nitrogen (N),
  phosphorus (P), and potassium (K). These major
  nutrients usually are lacking from the soil first
  because plants use large amounts for their growth
  and survival. 
• The secondary nutrients are calcium (Ca),
  magnesium (Mg), and sulfur (S). There are usually
  enough of these nutrients in the soil so
  fertilization is not always needed. Also, large
  amounts of Calcium and Magnesium are added when
  lime is applied to acidic soils. Sulfur is
  usually found in sufficient amounts from the slow
  decomposition of soil organic matter, an
  important reason for not throwing out grass
  clippings and leaves.

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Micronutrients

• Micronutrients are those elements essential for
  plant growth which are needed in only very small
  (micro) quantities . The micronutrients are boron
  (B), copper (Cu), iron (Fe), chloride (Cl),
  manganese (Mn), molybdenum (Mo) and zinc (Zn).
  Recycling organic matter such as grass clippings
  and tree leaves is an excellent way of providing
  micronutrients (as well as macronutrients) to
  growing plants.

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Soil Quality

• Topsoil the result of erosion and
  decomposition.
• Loams-the most fertile soils. Provide both
  nutrients and air spaces.
• Contains essential nutrients and a vast number of
  living organisms. The living organisms aerate
  and provide decomposing organisms to return
  nutrients to the soil.

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Clay and Ion Exchange

• Clay is negatively charged. This negative
  charges allows water molecules to stick. This
  water is a solution of minerals in the form of
  ions for the roots to absorb.
• Negatively charged ions dont bind t the clay and
  are therefore easily picked up by the roots.
• Positively charged ions such as potassium and
  calcium are bound tightly to the clay and are
  picked up by ion exchange. The root exchanges
  hydrogen ions for the minerals.

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Soil Conservation

• Sustainable agriculture is centered around
  sustaining the top soil. Disasters such as the
  Dust bowl have occurred because there was no soil
  conservation.
• Fertilizers- adds essential minerals back to
  soil. Must be done in a way that preserves soil
  pH and doesnt pollute ground water.
• Irrigation- must be done in a way that provides
  water with out destroying the water sources or
  altering the salinity of the soil.
• Erosion- over farming removes the plant roots
  from the soil that help hold the top soil in.
  Dry windy conditions cause the top soil to erode.
  Planting patterns such as adding trees to the
  perimeter of farmed land can help prevent
  erosion.
• Soil reclamation- rehabilitation soil.
  Phytoremediaiton uses plans that are able to
  extract pollutants from the soil.

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Nitrogen- the greatest limiting factor to plant
growth.

• Soil Bacteria and nitrogen. Plants cant take
  nitrogen from the air. Nitrogen is made
  available through bacteria in the soil.
• Decomposition releases ammonia into the soil
• Nitrogen fixing bacteria takes N2 and turns it
  into NH3(ammonia) which will then from
  NH4(ammonium ion). Plants can pick up ammonium.
• Most nitrogen is taken up in the form of NO3-
  (nitrate) Ammonium is converted to nitrate by
  nitrifying bacteria.

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Symbiosis and Bacteria

• Nitrogen fixation occurs in root nodules
  containing nitrogen fixing bacteria in the legume
  family. The bacteria provides the plant with
  nitrogen and the plant provides carbohydrates to
  the bacteria.

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Symbiosis and Fungus

• Mycorrhizae- fungus on the roots that have a
  mutualistic relationship with plants. The fungus
  increases surface area for the root, secrete
  growth factors, and protect the plant from
  pathogenetic bacteria. In return the plant
  provides carbohydrates to the fungus.

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Nutritional Adaptations of Plants

• Epiphytes- grows on another plant. Usually
  absorb water and minerals through leaves rather
  than roots. Growing anchored on a tree gives
  greater access to sunlight.
• Parasitic Plants- absorb sugars and minerals from
  roots that enter the host plant
• Carnivorous plants- live in soils that lack
  nitrogen. Use modified leaves to trap and digest
  insects.