ES101 Lecture Notes - Lecture 15: Tillage, Soil Conservation, Crop Rotation
Week 6, Lecture 1: Soils
What is Soil? → A mixture of organic material, inorganic material, and living organisms
- ½ to ⅔ of China’s agricultural land is in bad condition (same with India, Middle East, look
for agricultural land elsewhere)
- Some places have lots of good soil, others may have none at all (good soil at root of
good human development)
- Soil is fragile, it takes decades or more to form a few inches of soil, soil can be removed
from poorly managed land in a single season
Soil gets washed downhill, best soil is down at the bottom of the land
Important Characteristics
- Larger soil particles have larger spaces between them (are more porous)
- Smaller particles have a greater proportion of surface area relative to volume
- Water and nutrients tend to cling to surfaces
Clay Particles Under Microscope
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Document Summary
A mixture of organic material, inorganic material, and living organisms. To of china"s agricultural land is in bad condition (same with india, middle east, look for agricultural land elsewhere) Some places have lots of good soil, others may have none at all (good soil at root of good human development) Soil is fragile, it takes decades or more to form a few inches of soil, soil can be removed from poorly managed land in a single season. Soil gets washed downhill, best soil is down at the bottom of the land. Larger soil particles have larger spaces between them (are more porous) Smaller particles have a greater proportion of surface area relative to volume. Water and nutrients tend to cling to surfaces. Large surface area to which water molecules can adhere. Surface may also have a negative electrical charge, increasing adhesion of water and movement of nutrients. For agricultural production, a soil containing a mixture of particle sizes is desirable.
