HUMAN ACTIVITIES AFFECT SOIL
forces break rocks apart and form soil, which supports life.
Mechanical and chemical forces break
Weathering and organic processes form
Human activities affect soil.
SOIL IS A NECESSARY
- Soil helps
sustain all life on Earth by:
the growth of plants, which supply food and oxygen for animals.
crops such as cotton (clothing), medicines, lumber.
water as it drains through the ground.
sown remains of plants and animals, releasing nutrients that living plants
a home for many organisms.
LAND-USE PRACTICES CAN
have been farming for more than 10,000 years.
have improved, but farming still has some harmful effects and can lead to
often add fertilizers that may harm microorganisms that produce natural
also add to water pollution when runoff carries excess nutrients to
may lead to soil loss from clearing of trees and other plants. Wind and water may carry soil away.
occurs when farm animals eat large amounts of the land cover.
may lead to desertification-
the expansion of desert conditions in areas where the natural plant cover has
CONSTRUCTION AND DEVELOPMENT
- To make
roads, houses, malls and office buildings, people need to dig up the
plant cover loosens the soil and water and wind can carry it to lower
lying areas. This causes mud to
build up in streams and rivers and flooding results.
- Strip and
open pit mining cause soil loss.
rocks and minerals to the air and rainwater accelerate the chemical
drainage from sulfide minerals being exposed can lead to the production of
sulfuric acid. This can pollute the
soil in surrounding areas.
SOIL CAN BE PROTECTED
practice of planting different crops in the same field over different
years or growing seasons. This
works because different crops may replace nutrients or bacteria that
produce nutrients in the soil.
tillage- includes several methods of reducing the number of times fields
are tilled, or plowed, in a year.
This will reduce soil erosion.
flat, steplike areas built on a hillside to hold
rainwater and prevent it from running downhill. Crops are planted on the terraces.
plowing- the practice of plowing along the curves, or contours, of a
slope. This helps to channel
rainwater so that it does not run straight downhill and carry away
soil. Strip-cropping (where strips
of grass or shrubs are planted between crops) is often combined with this.
rows of trees planted between fields to reduce the force of winds that
carry the soil.