Warm-Up Review What are the 5 components in soil? Air and Water make up about _____ % of soil by volume. What is an example of mechanical weathering? What process transports sediments from one place to another? During a rainstorm, which soil is more likely to have poor drainage: clayey or sandy soil?

Soil Issues and Conservation

Soil Degradation Soil used as a resources leads to degradation Renewable resources BUT it takes 200-1000 years to form 1” of top soil So, it must be protected, conserved What are the main causes of soil degradation? Crop production Livestock production Deforestation

Soil Issues Erosion Desertification Salinization

Soil Erosion Erosion – wearing away of soil by wind or water Causes – farming: loosens soil so it is more easily eroded by wind or water Problems – when topsoil wears away, crops cannot be grown Sediments in rivers, lakes, etc.

The Dust Bowl

Soil Erosion The Great Dust Bowl 1930 Massive effort plowing of prairies to plant wheat started during WWI Drought Huge dust storms Lead to the Soil Conservation Act (SCA), which established the Soil Conservation Service (SCS)- now known as the Natural Resources Conservation Service (NRCS) Includes soil, and water quality and pollution

Desertification Process by which land in arid or semiarid areas becomes more desert-like because of human activities Causes – overgrazing, crops are planted too frequently, farming methods

Salinization Occurs in arid and semi-arid regions where lots of groundwater is used to irrigate crops High evaporation rate Salts build up in soil over time as groundwater evaporates on surface Plants have difficulty growing in salty soil

Soil Conservation Strategies http://www.mda.state.mn.us/protecting/conservation /practices.aspx Google: Soil conservation practices Minnesota

Contour Farming

Tilling the soil

No-till Farming

Ridge-till farming

Mulch-till farming (1)

Terracing

Cover crops

Windbreaks

Strip cropping

Wrapping Up: Describe 3 methods of soil conservation used in agriculture Provide one reason why soil conservation is important. What region of the country would soil salinization be a problem?

Answers 1. No-till/reduced till, windbreaks, cover crops, contour farming, strip-cropping, terrace farming, agro-forestry 2. Top soil takes a long time to regenerate, if you lose topsoil, you lose nutrients, runoff a pollutant 3. Southwest and California (arid and semi-arid climates reliant on irrigation)

Soil Conservation Strategies No till/reduced till agriculture Leaves debris in field after harvest Protects from wind/water; Decomposition recycles nutrients Less CO2 emissions

Soil Conservation Strategies Cover-Cropping Planting a crop that covers the soil in fall, winter, and early spring Legumes are sometimes used to restore Nitrogen to soil and improve fertility

Soil Conservation Strategies Windbreaks or shelter breaks Wind barricade; trees or fencing Reduces soil loss from wind

Soil Conservation Strategies Contour farming (low slopes) & Terracing (steep slopes) Plowing & planting perpendicular to slope; large steps cut into hillside; Both control water flow

Soil Conservation Strategies Intercropping & Agroforestry (alley cropping) Multiple plant species in one area Tall and short plantings; wind and water flow controlled

Soil Conservation Strategies Silt Fencing at Construction sites Keeps sediments on-site, less runoff

Farming Lingo “Tillage” = plowing. Farmers plow their fields to expose the topsoil for seeds to be planted. Ex: “No-till” farming does NOT plow the soil “Yield”- the amount of a particular crop harvested per unit area: 50 bushels of corn/acre “Acre”- 43,560 ft2, American farm unit “Hectare”- 10,000 m2, Metric farm unit (>acre) “Inputs”- resources put into growing a particular crop: fertilizers, pesticides, seeds, equipment, plowing