Environmental Science Chapter 9 Notes #2

Agriculture and Soil Arable Land – Fertile land that can grow crops well Amount decreases every year Population growth, erosion, poor farming methods World wide 1/5th was lost in just 15 years 1985 To 2000 In comparison to 10,000 years of farming Houses, roads, mines, farms left bare

Agriculture and Soil Ancient Methods of Farming Plowing Fertilization People/animals, cutting through/turning over) Fertilization manure Irrigation Digging ditches for water to flow through Pest control Pulling weeds, covering plants, etc) Technology has made it easier, increases erosion Machinery Synthetic fertilizers Sprinklers, advanced water systems Chemicals that kill pests

Agriculture and Soil Fertile Soil Supports rapid growth of healthy plants Plants grow in topsoil Loose surface layer Fertile- consists of rock, water, air, organic matter Living Things Fungi/bacteria/microorganisms – decompose Bacteria “fix” nitrogen Worms/insects/break up soil, letting in air (aeration) & water Bottom = bedrock

Agriculture and Soil Takes 1000’s of years to form a few cm of soil Bedrock breaks up due to temp changes and moisture (causing breaking/cracking) Mixes with organic decaying matter, water and air Voila! Soil has formed!

Agriculture and Soil Topsoil erosion Wearing away of topsoil by wind and water In US 50% of topsoil has been lost in the last 200 years One of top ecological problems we face today Plowing and harvesting contribute to erosion Produces loose surface area that can blow/wash away Removes roots that hold soil in place Clearing of trees increases amt of water flowing over the ground Trees absorb tons of water

Agriculture and Soil Desertification Loss of topsoil that destroys fertility Result of too many crops grown in the land (no fallow time) Overgrazing (no fallow time) Especially severe in dry areas – no water holding soil together Results in erosion

Agriculture and Soil Soil Conservation 1. Contour plowing Strips of vegetation in between plowed areas 2. No Till Farming Slits to plant new crop among the remains of the old crop 3. Organic v. Inorganic Fertilizer Organic helps replenish the soil

Agriculture and Soil Sustainable agriculture Low in Put Farming Without lots of energy or pesticides & fertilizers Example: Organic Farming No synthetics

Agriculture and Soil Salinization Accumulation of salts in soil Caused by irrigation Ground Water has more salt than rainwater Most irrigation comes from ground and rivers When it evaporates, leaves behind salt, kills seedlings Irrigation also causes groundwater levels to rise, resulting in the same effect

Agriculture and Soil Old and New Foods Researchers are looking at ancient and new plants for 2 purposes To find foods that grow easily and have a high percent yield Plants that improve soil conditions so the area can again be used for agricultural purposes

Agriculture and Soil Old and New Foods – Aquaculture “Fish Farming” Many ponds, raising fish of different ages, to be harvested Water circulates through bring in oxygen and removing waste Fish Ranch Example- salmon, raised and released No fishing zones to reduce over harvesting 23% of seafood comes from aquaculture Drawbacks Uses local water supply/wetlands are sometimes damaged