Soils and Civs

Lectures 21 and 22

Explain the benefits of tillage

Destroys pests' shelters and disrupts their lifecycles, Exposes pests to predators and unfavorable conditions, Distributes soil nutrients throughout the soil, Aerates the soil, Controls weeds, Makes other farm cultural practices easier to undertake

Briefly explain the history of the plow

6000 years BC, scratch plow (a frame holding vertical wooden stick that was dragged through topsoil), wheel added at 400 BC, iron plow from China in 100 BC, first commercial plow in 1730, moldboard plow made in 1788

Explain the benefits of plowing

weed control

Explain the detriments of plowing

simulates soil microbes, reduces organic matter, destroys soil structure, encourages soil erosion, uses energy

Why is clean row cultivation bad

no soil cover, caused topsoil to be blown away easily during the Dust Bowl

Why are conservation practices practical

addresses erosion control

Why is “no till” a good option

no maintenance, little or no additional cost, improved yield through water conservation, improved environmental quality

How did changes in equipment and herbicides impact NT adoption

smaller equipment, cut and slice through heavy residue, good seed placement and coverage, lower operating costs

How did the 1985 Farm Bill boost NT acreage

denied subsidies to farmers who did not attempt to reduce soil erosion on their most erodible land

What are the three conservation agriculture principles

permanent soil cover, minimum soil disturbance, diversified crop rotations

Who is Amon Sam and where does he farm?

Amon Sam is a farmer in Masembura. He is able to farm sandy soil because he has evenly spread mulch. He covers the crops with fertilizers. The neighbor's cows ate his mulch.

What’s the big deal about Carbon

the 15th most abundant element on earth by mass, second most abundant element in the human body, 81% of the carbon is stored in rocks, last 19% is stored in the ocean, atmosphere, plants, soil, and fossil fuels

What are the major pools/reservoirs of carbon in the carbon cycle

lithosphere, oceans, fossil pool, soil organic matter, atmosphere, plant biomass

What causes the greatest net increase in atmospheric carbon

fossil fuels

What makes carbon special

abundant, unique ability to form many compounds

How does carbon form so many compounds

carbon is a tramp

Why is carbon a tramp

readily bonds with many other elements (hydrogen, nitrogen, oxygen, phosphorus, and other carbon atoms), can form 4 bonds with up to 4 other atoms

How does carbon bond so easily with other elements OR What enables carbon to form stable connections to other atoms

small size allows for carbon to form covalent bonds with other small elements

How does carbon form so many compounds OR How does carbon form a limitless variety of molecules

can form single, double, or triple bonds that create structures like chains and rings

How many organic compounds are there

unlimited

Why is there a separate science devoted to organic carbon

Because carbon forms a huge variety of simple to complex and stable molecules that are essential life that no other element does

What are examples of organic compounds

sugars, proteins, lipids, alcohol, fuels

Who produces organic compounds

organisms (plants, animals, bacteria, fungi)

Why is carbon important

all life on earth is carbon based

Why are the bonds in CO2 stronger than CH4

In CO2, carbon forms 2 double covalent bonds with oxygen, In CH4, carbon forms single bonds with hydrogen

What’s the big deal about carbon dioxide

a stable and unreactive molecule

Who/What can break down CO2’s double covalent bonds

plants, algae, and cyanobacteria

What biological processes in the carbon cycle are important to life on earth

photosynthesis and cellular respiration

Which biological processes converts carbon dioxide into organic molecules

photosynthesis

Which biological and chemical processes burn sugar to create energy

respiration and decomposition

Where did the soil go that used to be as tall as the subsidence post in the Belle Glade Florida Research Center?

into the air

What is the major soil order of the US prairies/grasslands

mollisols

What are the common major soil orders in Tennessee

Alfisols and Ultisols

Why does the area that has enough rain to grow trees have soils that are not very organic

roots of water loving plants (trees) don’t have to go deep to find water

So how do the deeps roots of prairie grasses escape the voracious microbes

soil microbes live mostly in the top 6 inches of soil

How quickly is soil lost and formed

Lost: 0.25”/year. Formed: one inch may take 200-10000 years

What’s the difference between losing and gaining soil carbon

losing is a fast process while gaining is a slow process

What areas show recent declines in soil carbon

the northern regions

What is permafrost

soil found in longstanding cold climates