APES Unit 5 Soil Conservation

dust bowl

a nickname for the Great Plains regions hit by drought and dust storms in the early 1930s

Homestead Act of 1862

Encouraged westward settlement

-led to a massive influx of new and inexperienced farmers across the Great Plains.

-poor farming techniques, prolonged drought, and high winds led to the dust storms that lasted for a decade

soil conservation act f 1935

resulted from the dust bowl, established the Soil Erosion Service to help correct the enormous erosion problems in the Great Plains states

best method of soil conservation

keep vegetation covering the ground

conservative-tillage farming

minimizing the amount of tilling and plowing of soil

terracing

creating level planting beds on sloped land to reduce erosion and increase water retention

contour farming

planting crops across the slope of the land rather than up and down the slope

strip cropping

alternating rows of harvested crop with another that completely covers the ground and/or enriches soil (a legume)

intercropping

planting multiple species of plants which have different soil, light, and harvesting needs

advantage of milpas (polyculture)

-different species makes it harder for a pest to spread from plant to plant

-larger leaves of squash help shade out weeds.

-squash and beans produce deterrent chemicals against pests.

-beans are legumes which enrich the soil with N.

-tall corn helps protect squash and beans from intense heat of sun.

-multiple harvesting times gives farmer product throughout the growing season.

-more roots in the ground year round reduces erosion!

alley cropping/agroforestry

planting crops in "alleys" between trees and shrubs that provide protection from wind.

windbreak

planting trees around fields for protection from wind.

crop rotation

alternating soil degrading crops with soil restoring crops {legumes} after each growing season

organic fertilizers

-animal manure (feces and urine)

-green manure (freshly cut plant matter)

-compost (broken down organic matter)

-increase nutrients and the water holding capacity of soil

inorganic fertilizers

-replace N, P, K only

-without proper control, these can runoff and cause algal blooms in bodies of water

-algal blooms lead to a decrease in DO (dissolved oxygen)!

-release N2O (greenhouse gas)

4 "r"s of fertilization

-right source (best fertilizer to meet plants' needs)

-right rate (correct amt--not more than needed)

-right time (based on weather/rain events to prevent run-off)

-right place (only where most needed)

effects of soil erosion

seriously reduce agricultural and forestry production and degrade the quality of aquatic ecosystems.

rachel carson

wrote silent spring which warned about the dangers of pesticides.

what organisms are hurt by pesticides?

-beneficial insects like bees and butterflies are also harmed by broad spectrum pesticides.

-broad spectrum pesticides are designed to kill a large range of insects by interfering with insect physiology and/or reproduction.

pesticides

(the killer of a pest) can be insecticides, herbicides, fungicides, or rodenticides.

broad spectrum pesticides

toxic to many species.

-first broad spectrum pesticides were arsenic-based (lead arsenate).

selective pesticides

specifically designed to kill a certain group of organisms.

first generation pesticides

are/were toxic inorganic compounds made by humans. compounds were based on toxins found in plants

second generation pesticides

synthetic organic chemicals that humans create in labs

-DDT, a chlorinated hydrocarbon, was the 1st one

-atrazine is common pesticide used today

-neonicotinoids are newer insecticides that were originally thought to be less harmful to ecosystems, HOWEVER they are especially toxic to bees

pesticides vary in persistence...

=how long that chemical remains in the environment.

-many persistent pesticides are dioxins/ chlorinated hydrocarbons.

DDT

-dichlorodiphenyltrichloroETHANE

-dioxin and remains present, in the environment, for decades.

-causes the thinning of eggshells in birds, which was one factor that led to the bald eagle population becoming endangered.

dioxins

-biologically magnify; and it is thought that all humans have trace dioxin levels stored in our fat.

-dioxins are endocrine disruptors, which interfere with sexual development and reproduction.

IPM

integrated pest management, alternative to chemical pesticides

-takes into consideration the entire ecology of a pest situation.

-when using IPM, a farmer develops a control strategy to minimize economic losses.

-IPM minimizes threats to human health but may be complex and expensive.

physical controls

IPM strategy, factors that influence the habitat like crop rotation or intercropping

biological controls

IPM strategy, assisting a predator or competitor of the pest by using insect pheromones or food to attract the predator or competitor; bat boxes; planting plants that produce natural deterrent chemicals

chemical controls

IPM strategy, some pesticide or herbicide used as minimally as possible