5.3 soil degradation and conservation

Question 1

fertile soil contains

Answer 1

• organic matter to provide soil moisture and structure
• healthy soil community to break down organic matter and return nutrients
• nutrients and minerals
• suitable pH between 5.5 and 7.5, less = more acidic

Question 2

decomposition of DOM

Answer 2

• invertebrates mix organic matter into soil making it available for other organisms
• digest organic matter, break down by bacteria
• bacteria releases nutrients into the soil

Question 3

soil non-renewable resource

Answer 3

• rate of soil degradation/loss faster than rate of soil formation

Question 4

erosion

Answer 4

• soil particles transported from one place to another
• typically removes fertile topsoil

Question 5

water erosion

Answer 5

1. detachment
   - raindrops hit soil, free soil particles
   - run off detaches more soil particles
2. transport
   - flow of water carrying soil particles
3. deposition
   - water slows down, soil particles are deposited

Question 6

wind erosion

Answer 6

• dry regions, exposed soil surfaces
• light, easily picked up by wind currents
• damage plants in their path, reduce visibility

Question 7

chemical degradation
salinization

Answer 7

• water evaporates and leaves behind salt
• salt accumulates, soil becomes saline
• produce unable to grow

Question 8

chemical degradation
acidification

Answer 8

• increase in hydrogen ion concentration, lowering the pH
• caused by acid deposition, leaching/removal of nutrients, use of ammonium based fertiliser

Question 9

chemical degradation
nutrient depletion

Answer 9

• over exploitation
• reduces the capacity of the soil to support further plants
• artificial fertilizers don’t contain all nutrients needed

Question 10

chemical degradation
chemical pollution

Answer 10

• accumulation of toxic metals, trash, disposing

Question 11

physical degradation

Answer 11

• soil compaction, heavy machinery and animals
• air particles lost, decreased porosity, waterlogged, erosion

Question 12

threats to soil
urbanization

Answer 12

• loss of soil cover, cities
• urban soil, compaction and pollution

Question 13

threats to soil
livestock overgrazing

Answer 13

• vegetation removal livestock, soil exposed, wind/water erosion

Question 14

threats to soil
deforestation

Answer 14

• soil exposed
• reduces water infiltration into soil, increases water run off
• water erosion, organic matter water = water pollution
• lower dissolved oxygen, algae blooms, eutrophication

Question 15

threats to soil
farming

Answer 15

• tillage, bare, erosion
• monoculture, extract specific nutrients, nutrient poor
• multiple crops per year, remove nutrients faster rate than being replaced
• excessive irrigation, water erosion, salinization
• chemicals, damage microbial community
• cultivating steep slopes
• areas not suitable for farming

Question 16

threats to soil
desertification

Answer 16

• dry regions, soil loss and degradation contributes to desertification
• threatens food security

Question 17

reducing water erosion

Answer 17

• vegetation cover
• controlling run off, capturing it, terracing, expensive but effective
• strip cropping
• buffer strips, permanent vegetation
• increase infiltration of water, manure, mulch, avoid compaction, conservation tillage

Question 18

conservation tillage method

Answer 18

• crop residue is left as mulch on the surface
• reduces run off and water erosion
• high management required, not suitable for all types of crops, weeds

Question 19

reducing wind erosion

Answer 19

• wind breaks, large shrubs or trees, capture blowing soil, reduce wind velocity, deflect wind, habitat
• vegetation cover
• conservation tillage

Question 20

reducing salinization

Answer 20

• not overwatering
• watering night or late afternoon reduces evaporation
• good drainage
• flushing out excess salts

Question 21

managing soil nutrient levels

Answer 21

• addition of organic matter
• growing green manure
• addition of synthetic fertilizers
• limiting addition of limestone to raise soil pH
• crop rotation, 3-4 year cycle

Question 22

control grazing

Answer 22

• restricting number of animals and time spent in one area

Question 23

conventional tillage

Answer 23

• prepare soil for sowing seeds
• soil broken up by ploughing
• open and loose soil structure, aerated and moist, reduces weeds
• land is cleared of all debris

Question 24

quesungual system in honduras

Answer 24

• replace shifting agriculture
• in between plots, 20-30 large trees kept
• range of crops planted
• conservation tillage, plant reside covered soil
• increased organic content, soil structure, moisture retention, nutrient levels, food production/nutrition, co2 absorption, food security
• decreased soil erosion

Question 25

commercial farming in south australia

Answer 25

- shallow top soil, low fertility, dry and arid climate - sever soil erosion, over grazing, ploughing - combat erosion government promoted no till farming, crop rotation, wind breaks, cover crops - better irrigation to reduce soil salinization - large percentage of farmers adopting no till