environmental science chapter 9 notes #2. agriculture and soil arable land – arable land –...
TRANSCRIPT
Environmental ScienceEnvironmental Science
Chapter 9Chapter 9
Notes #2Notes #2
Agriculture and SoilAgriculture and Soil
Arable Land –Arable Land –• Fertile land that can grow crops wellFertile land that can grow crops well• Amount decreases every yearAmount decreases every year
Population growth, erosion, poor farming Population growth, erosion, poor farming methodsmethods
• World wide 1/5World wide 1/5thth was lost in just 15 years was lost in just 15 years 1985 To 20001985 To 2000 In comparison to 10,000 years of farmingIn comparison to 10,000 years of farming Houses, roads, mines, farms left bareHouses, roads, mines, farms left bare
Agriculture and SoilAgriculture and Soil Ancient Methods of FarmingAncient Methods of Farming
• PlowingPlowing People/animals, cutting through/turning over)People/animals, cutting through/turning over)
• FertilizationFertilization manuremanure
• IrrigationIrrigation Digging ditches for water to flow throughDigging ditches for water to flow through
• Pest controlPest control Pulling weeds, covering plants, etc)Pulling weeds, covering plants, etc)
• Technology has made it easier, increases erosionTechnology has made it easier, increases erosion
Machinery
Synthetic fertilizers
Sprinklers, advanced water systems
Chemicals that kill pests
Agriculture and SoilAgriculture and Soil
Fertile SoilFertile Soil• Supports rapid growth of healthy plantsSupports rapid growth of healthy plants• Plants grow in topsoilPlants grow in topsoil
Loose surface layerLoose surface layer Fertile- consists of rock, water, air, organic matterFertile- consists of rock, water, air, organic matter Living Things Living Things
• Fungi/bacteria/microorganisms – decomposeFungi/bacteria/microorganisms – decompose• Bacteria “fix” nitrogenBacteria “fix” nitrogen• Worms/insects/break up soil, letting in air (aeration) & Worms/insects/break up soil, letting in air (aeration) &
water water
• Bottom = bedrockBottom = bedrock
Agriculture and SoilAgriculture and Soil Takes 1000’s of years Takes 1000’s of years
to form a few cm of soilto form a few cm of soil Bedrock breaks up due Bedrock breaks up due
to temp changes and to temp changes and moisture (causing moisture (causing breaking/cracking)breaking/cracking)
Mixes with organic Mixes with organic decaying matter, water decaying matter, water and airand air
Voila! Soil has formed!Voila! Soil has formed!
Agriculture and SoilAgriculture and Soil Topsoil erosionTopsoil erosion
• Wearing away of topsoil by wind and waterWearing away of topsoil by wind and water• In US 50% of topsoil has been lost in the In US 50% of topsoil has been lost in the
last 200 yearslast 200 years One of top ecological problems we face todayOne of top ecological problems we face today
• Plowing and harvesting contribute to Plowing and harvesting contribute to erosionerosion
Produces loose surface area that can Produces loose surface area that can blow/wash awayblow/wash away
Removes roots that hold soil in placeRemoves roots that hold soil in place
• Clearing of trees increases amt of water Clearing of trees increases amt of water flowing over the groundflowing over the ground
Trees absorb tons of waterTrees absorb tons of water
Agriculture and SoilAgriculture and Soil
DesertificationDesertification• Loss of topsoil that destroys fertilityLoss of topsoil that destroys fertility• Result of too many crops grown in the Result of too many crops grown in the
land (no fallow time)land (no fallow time)• Overgrazing (no fallow time)Overgrazing (no fallow time)• Especially severe in dry areas – no water Especially severe in dry areas – no water
holding soil togetherholding soil together• Results in erosion Results in erosion
Agriculture and SoilAgriculture and Soil
Soil ConservationSoil Conservation• 1. Contour plowing1. Contour plowing
Strips of vegetation in between plowed Strips of vegetation in between plowed areasareas
• 2. No Till Farming2. No Till Farming Slits to plant new crop among the remains of Slits to plant new crop among the remains of
the old cropthe old crop
• 3. Organic v. Inorganic Fertilizer3. Organic v. Inorganic Fertilizer Organic helps replenish the soilOrganic helps replenish the soil
Agriculture and SoilAgriculture and Soil
Sustainable agricultureSustainable agriculture Low in Put FarmingLow in Put Farming
• Without lots of energy or pesticides & Without lots of energy or pesticides & fertilizersfertilizers
Example:Example:• Organic FarmingOrganic Farming• No syntheticsNo synthetics
Agriculture and SoilAgriculture and Soil
SalinizationSalinization• Accumulation of salts in soilAccumulation of salts in soil• Caused by irrigationCaused by irrigation
Ground Water has more salt than rainwaterGround Water has more salt than rainwater Most irrigation comes from ground and Most irrigation comes from ground and
riversrivers When it evaporates, leaves behind salt, kills When it evaporates, leaves behind salt, kills
seedlingsseedlings Irrigation also causes groundwater levels to Irrigation also causes groundwater levels to
rise, resulting in the same effectrise, resulting in the same effect
Agriculture and SoilAgriculture and Soil
Old and New FoodsOld and New Foods Researchers are looking at ancient Researchers are looking at ancient
and new plants for 2 purposesand new plants for 2 purposes• To find foods that grow easily and have To find foods that grow easily and have
a high percent yielda high percent yield• Plants that improve soil conditions so Plants that improve soil conditions so
the area can again be used for the area can again be used for agricultural purposesagricultural purposes
Agriculture and SoilAgriculture and Soil Old and New Foods – AquacultureOld and New Foods – Aquaculture
• ““Fish Farming”Fish Farming” Many ponds, raising fish of different ages, to be Many ponds, raising fish of different ages, to be
harvestedharvested Water circulates through bring in oxygen and removing Water circulates through bring in oxygen and removing
wastewaste
• Fish RanchFish Ranch Example- salmon, raised and releasedExample- salmon, raised and released No fishing zones to reduce over harvestingNo fishing zones to reduce over harvesting
• 23% of seafood comes from aquaculture23% of seafood comes from aquaculture• DrawbacksDrawbacks
Uses local water supply/wetlands are sometimes Uses local water supply/wetlands are sometimes damageddamaged