Chapter 40 13-03-03 1:59 PM
Micronutrients: any mineral required by an organism in small trace
Macronutrients: minerals needed in large amounts.
Essential Nutrients: any of the essential amino acids, fatty acids, vitamins,
and minerals required in a plant.
Nitrification: a metabolic process in which certain soil bacteria convert
ammonia or ammonium ions into nitrites that are then converted by other
bacteria into nitrates, a form usable by plants.
40.1 Nutrition: Essential Materials
Hydroponics is Way to Study Plant Nutrition:
Hydroponics– an experimental method for identifying minerals absorbed into
plant tissues that were essential for growth
⋅ Scientist Sachs, measured various amounts of minerals and nutrients in
solutions, in which he grew plants.
⋅ By eliminating the elements on at a time, he determined the SIX essential
⋅ If you want to determine if a nutrient is essential, you include it in a
solution, and then transfer the plant to another solution that contains all
nutrients except the one you are testing… what happens?
• Normal growth? The nutrient is not essential
⋅ You must remember to supply air bubbles to the roots because it is an
⋅ Carbon, hydrogen and oxygen are the only plant nutrients not considered
to be minerals
• These nutrients are obtained from the air and water (the others are
obtained from the soil, or dissolved in water)
⋅ The amount of essential element adequate for one species may be toxic
for another 40.2 Soil
soil is a mixture od minerals, organic matter, air and water. Also contains
Soil is the source of water for most plants, and oxygen for cellular
respiration in the root cells.
The texture of the soil determines if the root systems have access to
sufficient water and dissolved oxygen… sand , silt and clay.
The relative proportions of the minerals determine the number and volume
of pores (air spaces). Also depends on the number of living organisms..
Humus holds a lot of water and provides a lot of vital nutrients.
Horizon A: Top Soil
• Most biological activity occurs here and is the most fertile.
• Most plant roots are concentr