Chapter 37: Soil & Plant Nutrition
(1) Visual Image
(7) Chapter Subheadings & Summaries
37.1 Soil contains a living, complex ecosystem
 Soil is multi-layered and is composed of organic (ie: dead organisms, fungi, bacteria)
and inorganic (minerals from weathered rock) materials
 Agriculture practices including irrigation and fertilization must be done with careful
consideration to avoid erosion of soil and to maintain soil integrity
37.2 Plants require essential elements to complete their life cycle
 Essential elements in plants include: carbon, oxygen, hydrogen, nitrogen, potassium,
calcium, magnesium, phosphorus, and sulfur
 Symptoms of mineral deficiency vary by species and type of deficiency, but can all
result in decreased photosynthesis, growth, and reproduction
 Genetic engineering has developed plants that are better designed to withstand less
than optimal soil conditions
http://www.greenhousecanada.com/images/stories/2008/OCT/1649-soil-nutrition-003.jpg
37.3 Plant nutrition often involves relationships with other organisms
 Bacteria play a key role in the nitrogen cycle and help plants convert atmospheric
nitrogen to usable nitrogen
 Fungi form mutualistic relationships with plant roots, increasing root surface area and
therefore, water absorption
 Unique nutritional adaptations of plants include epiphytes, parasitic and carnivorous
plants
(2) Key terms with definitions and examples
 Humus: remains of dead organisms and other organic matter
 Topsoil: humus and mineral particles released by weathering
 Fertilization: adding mineral nutrients to soil
 Phytoremediation: use of biotechnology to decontaminate
soil
 Macronutrients: elements required by plants in large
amounts
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Micronutrients: elements required by plants in small amounts
Rhizobacteria: soil bacteria that assist in nitrogen nutrition
Nitrogen fixation: reduction of atmospheric N2 to usable NH3 by
bacteria
Mycorrhizae: “fungus roots” that are mutualistic to plant roots,
increasing surface area for water and mineral absorption
Epiphytes: a plant that grows on another plant
(3) Research Method
The experiment in hydroponic culture
involves growing plants in mineral
solution, without soil, to determine
which elements are essential to plants.
A control group placed the plant in an
aerated solution with all minerals;
experimental solutions were aerated but
omitted one mineral (such as potassium)
to see the effect on the plants. If an
element was essential, deficiency
symptoms were observed and the plant
did not complete its life cycle.
(4) Exploring or Inquiry
In the Exploring (p. 798), the unusual
nutritional adaptations of plants are
examined.
 Epiphytes, such as staghorn ferns,
grow on another plant without
forming a parasitic relationship.
 Parasitic plants, such as mistletoe,
grow in association with another
plant and rob it of water, minerals,
or photosynthetic products.
 Carnivorous plants, such as
sundews, are photosynthetic but
supplement their mineral needs by
capturing insects or other small
animals.
(8) 3-2-1 Reflections
 3 Questions:
o What does it mean to say a plant has
completed its life cycle?
o How is genetic engineering of plants
performed?
o How would plant nutrition be changed if
not for their mutualistic relationships with
bacteria and/or fungus?
 2 Interesting Topics:
o Phytoremediation biotechnology
o Carnivorous plants
 1 Important Idea:
o Nutrition is essential for normal plant
structure and function and can be enhanced
by biotechnology and mutualistic
relationships.
(5) Evolution Connection
The mutualistic relationship between
plant roots and nitrogen fixing bacteria
could have existed before plants evolve.
The benefit to the bacteria in the
relationship is increased surface area;
without the plant, the bacteria can still
grow and metabolize/fix atmospheric
nitrogen, they would just do so by simply
living in the soil and not in association
with plant roots.
(6) Science, Technology, and Society or
Scientific Inquiry
The potential consequence of withdrawing
ground water for irrigation is that there will
overall be less water available for human
consumption. Water levels of lakes and
rivers may decrease. In addition, aquifers
that are depleted may cause the land
around it to be unstable.
As a society, countries need to make and
adhere to policies that would restrict the
use of groundwater for irrigation and
outline a plan for water conservation.
(9) Figure
The Nitrogen Cycle
http://www.ndsu.edu/pubweb/chiwonlee/plsc210/topics/chap13-nutrition/pg1a.jpg