Cover crop

• Crop planted between harvesting and next season’s planting

• Normally nitrogen-fixing• Prevents erosion

shelterbelts

• Windbreaker• Rows of trees or tall plants to slow wind

Conservation Tilling

• Tilling – Turn over soil before planting– Creates pores for air and water– More susceptible to erosion

• No-till method– Tractor drills deep holes to put seeds and fertilizer in– Seeds of each crop are planted among the remains of the

previous crop– the first crop hold the soil while the new crop develops

• Reduced-tillage– Disturbs surface soil slightly

• Require substantial herbicides and fertilizer

• Terracing- the hillsides are formed into large steps (small level fields)

• Labor-intensive• often used for growing crops

such as grapes for wine and coffee

Contour farming- used on gentle slopes -plowing is done across the slope of a hill instead of up and down.

•Both methods prevent water from running directly down hill and washing away all of the valuable topsoil.

Terracing and Contour plowing are conservation methods designed to prevent downhill erosion

Overgrazing

• Too many animals eat too much and impede plants’ regrowth

• Removes too much plant cover• More soil exposed for erosion• Non-native weedy plants invade the exposed

soil• Range managers tell ranchers rotate herds to

different locations

desertification• process by which land

in arid or semi arid areas becomes more desert like because of human activity.

ways desertification can occur:

–Over grazing- less roots to hold soil– Soil compaction–Hoof erosion–Over plowing – not enough fallow (rest)

time–Drought

The Dust Bowl

• 1930s desertification in Great Plains• Farming increased rapidly and ranchers

overgrazed land• Erosion by removing grasses• Drought occurred• Strong winds created dust storms

U.S. Policies

• Soil Conservation Act– Established soil conservation service, later

renamed Natural Resources Conservation Service– Worked with farmers to create conservation

plans before they receive subsidies• Conservation Reserve Program– Pays farmers to stop cultivating cropland that

erodes easily and place it in areas with conservation plans

Soil Pollution

• Irrigation– Providing water besides precipitation to crops– Can cause waterlogged crops and salinization

(buildup of salts)• Salinization– In hot areas, water and dissolved salts get pulled

up from lower horizons through evaporation and capillary action

– Water completely evaporates and salt left behind

Preventing Salinization

• Avoid planting crops where large amounts of water are needed

• Irrigate with water with low salt content• Don’t over-irrigate• Supply water close to roots (drip irrigation)• Plant salt-tolerant plants

pesticides chemicals used to kill insects, weeds, and other crop pests