3.1 Nutrient Cycles: Global Recycling
Nutrient cycles
describe the flow of nutrients in and out of stores as a result of biotic and
abiotic processes. Without human interference, nutrient cycles are almost perfectly balanced. Nutrients are recycled by global cycles through the earth’s
air, land, water, and living organisms. Nutrients are the elements that are
essential to living, grow and reproduce of organisms.
3.2 Nutrients
All of the essential
elements are by required for plant growth and completion of the plant life
cycle from seed to seed. Some essential elements are needed large quantities
and others in much smaller quantities. However, from a practical standpoint,
three of the six essential macronutrients are most often "managed" by
the addition of fertilizers to soils, while the others are most often found insufficient
quantities in most soils and no soil amendments are required to supply adequate
supplies.
3.3 Categories of nutrients
Nutrients in
soils are can be divided into two categories as macronutrients and micronutrients. Macronutrients are also can be divided into two categories as
primary nutrients and secondary nutrients.
3.2.1 Macronutrients
Macronutrients are those elements and compounds needed in
large quantities for a plant to grow.
3.2.1.1 Primary nutrients
These major nutrients usually are lacking from the soil first because
plants use large amounts for their growth and survival.
Ex: N, P
and
3.2.1.2 Secondary nutrients
There
are usually enough of these nutrients in the soil so fertilization is not
always needed.
Ex: Ca, Mg and S
3.2.2 Micro
nutrients
Micro-nutrients are those elements essential for plant growth which are needed in only very
small (micro) quantities and are sometimes called minor elements or trace
elements.
Ex: B, Cu, Fe, Mn, Mo, Zn, and Cl
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