Crops and SoilCrops and Soil

Questions to AnswerQuestions to Answer

How does traditional agriculture differ from How does traditional agriculture differ from modern agriculture?modern agriculture?

What are the major layers of soil?What are the major layers of soil?

Where would you find the most amount of Where would you find the most amount of living organisms in soil?living organisms in soil?

What are pesticides and why are they used?What are pesticides and why are they used?

How are pesticides both beneficial and How are pesticides both beneficial and harmful?harmful?

AgricultureAgriculture

The Earth has a limited area of The Earth has a limited area of arable landarable land, , land that can be used to grow crops.land that can be used to grow crops.

Basic processes of farming include:Basic processes of farming include: PlowingPlowing FertilizationFertilization IrrigationIrrigation Pest controlPest control

Traditional AgricultureTraditional Agriculture

Plows are traditionally pushed by the farmer Plows are traditionally pushed by the farmer or pulled by livestock.or pulled by livestock. Helps crops grow by mixing soil nutrients, Helps crops grow by mixing soil nutrients,

loosening soil particles, and uprooting weeds.loosening soil particles, and uprooting weeds.

Organic fertilizers, such as manure, are used Organic fertilizers, such as manure, are used to enrich the soil.to enrich the soil.

Fields are irrigated by water flowing through Fields are irrigated by water flowing through ditches.ditches.

Weeds are removed by hands or machine.Weeds are removed by hands or machine.

Modern AgricultureModern Agriculture

Machinery powered by fossil fuels is used to Machinery powered by fossil fuels is used to plow the soil and harvest crops.plow the soil and harvest crops.

Synthetic chemical fertilizers are used instead Synthetic chemical fertilizers are used instead of manure.of manure.

Overhead sprinklers and drip systems are Overhead sprinklers and drip systems are used for irrigation.used for irrigation.

SoilSoil

Why might we refer to fertile soil as the Why might we refer to fertile soil as the living living Earth?Earth?

How Soil FormsHow Soil Forms

Chemical Chemical WeatheringWeathering

Minerals in the rock Minerals in the rock chemically react with chemically react with substances to form new substances to form new materials.materials.

**New substance**New substance

Mechanical Mechanical WeatheringWeathering

Rocks physically Rocks physically breaking apart.breaking apart.

**Same substance, **Same substance, different formdifferent form

How Soil FormsHow Soil Forms

Temperature changes and moisture cause Temperature changes and moisture cause rock to crack and break apart.rock to crack and break apart.

It can take hundreds or even thousands of It can take hundreds or even thousands of years for these geological processes to form a years for these geological processes to form a few centimeters of soil.few centimeters of soil.

TopsoilTopsoil• The surface layer of soilThe surface layer of soil

• Usually richer in organic Usually richer in organic mattermatter

• Fertile topsoil is Fertile topsoil is composed of living composed of living organisms, rock organisms, rock particles, water, air, particles, water, air, and organic matter, and organic matter, such as dead or such as dead or decomposing decomposing organisms (humus).organisms (humus).

• Referred to as theReferred to as the A A Horizon.Horizon.

SubsoilSubsoil• Larger rock particles Larger rock particles

with organic matter, with organic matter, and inorganic and inorganic compounds.compounds.

• Referred to as Referred to as B B HorizonHorizon..

Rock Rock ParticlesParticles

• Rock that has Rock that has undergone weatheringundergone weathering

• Referred to as Referred to as C C Horizon.Horizon.

BedrockBedrock• Solid rock layerSolid rock layer

• Also referred to as Also referred to as Parent MaterialParent Material

Soil ErosionSoil Erosion

ErosionErosion is the wearing away of rock or soil by is the wearing away of rock or soil by wind and water.wind and water.

About half of the original topsoil in the U.S. About half of the original topsoil in the U.S. has been lost to erosion in the past 200 has been lost to erosion in the past 200 years.years.

Almost all farming methods increase the rate Almost all farming methods increase the rate of soil erosion.of soil erosion.

Land DegradationLand Degradation

Land degradation Land degradation happens when human happens when human activity or natural processes damage the land activity or natural processes damage the land so that it can no longer support the local so that it can no longer support the local ecosystem.ecosystem.

Soil usually erodes downhill; soil conservation Soil usually erodes downhill; soil conservation methods focus on preventing downhill methods focus on preventing downhill erosion.erosion. Contour plowingContour plowing No-till farmingNo-till farming

Enriching SoilEnriching Soil

Inorganic fertilizers (containing nitrogen, Inorganic fertilizers (containing nitrogen, potassium, and phosphorous) have increased potassium, and phosphorous) have increased food production.food production. If erosion occurs in areas where the soil has If erosion occurs in areas where the soil has

been fertilized with inorganic chemicals, been fertilized with inorganic chemicals, fertilizers and pesticides may pollute fertilizers and pesticides may pollute waterways.waterways.

Compost is used to enhance soil—using both Compost is used to enhance soil—using both organic and inorganic materials.organic and inorganic materials.

Pest ControlPest Control

PestPest- any organism that occurs where it is - any organism that occurs where it is not wanted or that occurs in large enough not wanted or that occurs in large enough numbers to cause economic damage.numbers to cause economic damage. Includes: insects, plants, fungi, Includes: insects, plants, fungi,

microorganismsmicroorganisms

PesticidesPesticides are chemicals used to kill insects, are chemicals used to kill insects, weeds, and other crop pests.weeds, and other crop pests. Can also harm beneficial plants, insects, Can also harm beneficial plants, insects,

wildlife, and even people.wildlife, and even people.

Questions to AnswerQuestions to Answer

How does traditional agriculture differ from How does traditional agriculture differ from modern agriculture?modern agriculture?

What are the major layers of soil?What are the major layers of soil?

Where would you find the most amount of Where would you find the most amount of living organisms in soil?living organisms in soil?

What are pesticides and why are they used?What are pesticides and why are they used?

How are pesticides both beneficial and How are pesticides both beneficial and harmful?harmful?