Title: Soil
1Soil
Ch 13 and CIE sources
2Today, we produce more food per person
By 2050, we will have to feed 9 billion people
- Food production currently exceeds population
growth - But not everyone has enough to eat
3Food security and undernutrition
- Food security guarantee of an adequate, safe,
nutritious, and reliable food supply - Providing food security to everyone will be one
of our greatest challenges - Undernutrition receiving fewer calories than
ones minimum dietary energy requirements - 925 million people do not have enough to eat
- Every 5 seconds a child starves to death
- Is due to poverty, politics, conflict, and
inefficiencies in distribution
4Food security
Indicators of hunger recently increased
- After declining for four decades, the number
and percentage of hungry people increased in
20082009 - Higher food prices and the economic slump
- The number of undernourished declined in 2010
- Hunger levels, as a percentage of population, are
lower than in the 1970s
5Overnutrition and malnutrition
- Overnutrition receiving too many calories each
day - Leads to heart disease, diabetes, etc.
- In the U.S., 60 of adults are overweight, 25
are obese - Worldwide, over 500 million people are obese
- These numbers will rise to 2.3 billion overweight
and 700 million obese by 2015 - Malnutrition a shortage of nutrients the body
needs - The diet lacks adequate vitamins and minerals
- Can lead to diseases
6Malnutrition can lead to diseases
- Kwashiorkor occurs when diet lacks protein or
essential amino acids - Occurs when children stop breast-feeding
- Bloated stomach, mental and physical disabilities
- Marasmus is due to protein deficiency and
insufficient calories - Wasting of the body
- Anemia and deficiency in iodine and vitamin A are
also prevalent
7Soil Formation
- The four major components of soil are
- Water (25)
- Air (25)
- Organic matter (6)
- Parent material (44)
- 2. Parent material is
- Bedrock which provides mineral content of
the soil, Ex - Sand, silt and clay
- Quartz SiO2
- Calcite CaCO3
- Feldspar KAlSi3O8
- Mica (biotite) K(Mg,Fe)3AlSi3O10(OH)2
8- 3. How is soil made from parent material? Include
the role of weathering and living organisms - Weathering (physical and chemical) creates small
pieces - Dead organisms- decay and release nutrients and
gases - living organisms also release nutrients and gases
- Parent material can be native to the area or
transported to the area by wind, water or a
glacier - EX
- Calcareous soils in Miami-Dade County are derived
from Miami limestone. Most of Miami-Dade County,
part of Broward County, and Monroe County
(including the Florida Keys). Broward also has
marl and stone sand bedrock
9- 4. Humus is Organic matter
- Dead and decayed organisms, ex plant matter
- How long does it take to make soil from bare
rock? - 10 000 years
Not hummus
10Soil the foundation for agriculture
- Soil a complex system consisting of
disintegrated rock, organic matter, water, gases,
nutrients, microorganisms - A renewable resource that can be depleted if
abused
- Soil contains
- Dead and living microorganisms
- Decaying material
- Bacteria, fungi, worms, insects, burrowing animals
Soil influences ecosystems as much as climate,
latitude, and elevation
11Soil forms slowly
- Parent material the base geologic material of
soil - Lava, volcanic ash, rock, dunes
- Bedrock solid rock comprising Earths crust
- Weathering physical, chemical, and biological
processes that form that convert rocks into soil - Biological deposition, decomposition, and
accumulation provide organic matter and nutrients - Humus spongy, fertile material formed by partial
decomposition of organic matter - Holds moisture and is productive for plants
12A soil profile consists of horizons
- Horizon each layer of soil
- Soil can have up to six horizons
- Soil profile the cross-section of soil as a
whole - Leaching movement of dissolved particles down
through horizons - Can deprive plants of nutrients
- Topsoil inorganic and organic material most
nutritive for plants - Vital for agriculture
13- Soil Profile
- 1. Describe the 5 Soil horizons
- O- Organic matter, leaf litter (duff),
- dead animals, decomposed litter
- A- Surface soil, decomposed organic
- matter and minerals, humus (fertile)
- B- Subsoil, leached nutrients
- C- Parent rock, weathered large
- unbroken rocks
- R (Bedrock)- mostly a continuous
- mass of hard rock
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16Soil Texture1. What is soil texture?
- Proportions of clay, sand and silt
- Particle size
- Smallest - clay less than .002mm
- - - Silt .002mm - .05mm
- largest - sand .05mm - 2 mm
-
17- 2. What is porosity?
- Ability to hold water
- 3.What is permeability?
- Ability of water to flow through the material
(rate) - 4. Compare permeability of sand and clay.
- Sand high, clay low
18- 5. What is a loam?
- A loam has about mixtures of clay, sand, silt
- and humus - best for growing crops.
- 6. How can soil texture be determined?
- Determined by particle size and feel
19- Soil type
- 1. What are the main Soil types?
- There are six main types of soil usually
discussed in agriculture, distinguished by the
size of the particle matter that makes up the
soil. - Sandy (water/minerals easily flow)
- Clay (no drainage)
- Silty (fertile, good drainage)
- Loamy (a mixture of soils)
- Chalky (alkaline)
- Peaty (acidic , undecomposed organic matter)
20Central Case Study Iowas Farmers Practice
No-Till Agriculture
- Repeated plowing and planting damage soil
- No-till farming benefits soil
- Saves time and money
- Does not decrease production
- Can help make agriculture sustainable
- Other conservation measures
- Careful use of fertilizers
- Preventing erosion
- Retiring fragile soils
21- Soil Erosion is the process by which soil and
rock are removed from the Earth's surface by wind
or water flow, and transported and deposited in
other locations. - Sheet erosion - surface water peels off fairly
uniform sheets of soil. - Rill erosion - fast flowing rivulets cut
- Small channels in soil.
- Gully erosion - rivulets join together to
- Cut wider, deeper ditches or gullies
- Two major impacts- loss of soil fertility and
pollution of near by waters
22Soil erosion
- Soil degradation loss of soil quality and
productivity - Has caused 13 loss of grain production
- Each year, we lose 1217 million acres of
cropland - Erosion, nutrient depletion, water scarcity,
salinization, waterlogging, pollution, loss of
organic matter - Erosion removal of material from one place to
another - By wind or water
- A problem when it happens faster than soil
formation - Deposition arrival of eroded material at a new
place
23Humans make land vulnerable to erosion
- Land is made vulnerable to erosion through
- Overcultivating fields poor planning, excessive
tilling - Overgrazing rangeland with too many animals
- Clearing forests on steep slopes or with large
clear-cuts
Erosion removes valuable topsoil, especially in
areas with steeper slopes, greater precipitation
intensities, and sparse vegetation
24Soil erosion is a global problem
- Humans are the primary cause of erosion
- It is occurring at unnaturally high rates
- In Africa, erosion could reduce crop yields by
50 over the next 40 years - The U.S. loses 5 tons of soil for every ton of
grain harvested
Degradation of topsoil and decreased crop yields,
added to population growth are leading
agricultures future to a crisis situation
25Soils Degradation
- Desertification - combination of
- Prolonged drought and human activities
- Lead to a reduction in the productive
- potential of land.
- Solutions Reduce
- Overgrazing
- Deforestation
- Destructive forms of farming, irrigation, and
mining
26Desertification reduces productivity
- Desertification a loss of more than 10
productivity - Erosion, soil compaction, deforestation,
overgrazing - Drought, salinization, water depletion, climate
change - Most prone areas arid and semi-arid lands
(drylands) - Desertification endangers the food supply of 1
billion people in over 100 countries - Costing tens of billions of dollars each year
- Climate change will worsen desertification by
changing rainfall patterns - 50 million people will be displaced in 10 years
27Causes of soil Degradation
- Deforestation
- No vegetation to hold the soil, soil is removed,
loss of soil fertility, pollutes and can silt up
rivers, decline in fish, flooding can worsen - Management prevent deforestation, manage forest
harvesting, replant
28Stepped Art
Fig. 10-6a, p. 219
29- Agriculture
- Overgrazing- livestock are grazed on land in an
unsustainable way (poorly managed) which leads to
soil erosion and compaction of soil (due to the
feet of the animals) - Solutions-Rotational grazing- land is not grazed
on until the plants have had enough time to grow
back, cattle supplied with other food sources, ex
hay - Over grazing can lead to desertification
30Overgrazing causes soil degradation
- Humans keep over 3.4 billion cows, sheep, and
goats - Overgrazing too many animals eat too much of the
plant cover and impede plant regrowth - Soil is degraded and compacted
- Increased erosion makes it hard for plants to
grow - Non-native plants invade, which are less
palatable to livestock and outcompete native
vegetation - Ranchers in the western U.S. are finding ways to
ranch more sustainably and protect the lands
health
70 of the worlds rangeland is degraded, costing
23.3 billion/year
31Effects of overgrazing can be striking
- Overgrazing sets into motion consequences that
degrade soil and grassland ecosystems
32Irrigation productivity with problems
- Irrigation artificially providing water to
support agriculture - Unproductive regions become productive farmland
- Waterlogging water suffocates roots in
overirrigated soils - Salinization the buildup of salts in surface
soil layers - Worse in dryland areas
Salinization inhibits production of 20 of
irrigated cropland, costing over 11 billion/year
33Soils Degradation
- Salinization - salts left on soil as
- irrigation water evaporates. Stunts crop
- growth and reduces crop yields.
- Waterlogging - farmers leach salts from
- Soils by applying large amounts of water.
- if water does not drain, saline water sits in
pools and damages roots of plants. - Solution- Drip irrigation, better drainage
34Prevention
Cleanup
Reduce irrigation Switch to salt- tolerant
crops (such as barley, cotton, sugar beet)
Flushing soil (expensive and wastes water) Not
growing crops for 2-5 years Installing under-
ground drainage systems (expensive)
Preventing and cleaning up soil salinization
35Conservation tillage saves soil
- Increases organic matter and soil biota
- Reducing erosion and improving soil quality
- Stores carbon in the soil and reduces fossil fuel
use
- Minimizes increased use of herbicides and
fertilizer - Uses green manure (dead plants as fertilizer) and
rotates fields with cover crops
Conservation tillage is used on 40 of U.S.
farmland
36CONSERVATON TILLAGE
Disadvantages
Advantages
Reduces erosion Saves fuel Cuts costs Holds
more soil water Reduces soil compaction Allows
several crops per season Does not reduce crop
yields
Can increase herbicide use for some
crops Leaves stalks that can harbor crop pests
and fungal diseases and increase pesticide
use Requires investment in expensive equipment
37Protecting soil crop rotation and contour farming
- Crop rotation growing different crops from one
year to the next - Returns nutrients to soil
- Prevents erosion, reduces pests
- Wheat or corn and soybeans
- Contour farming plowing perpendicularly across a
hill - Furrows slow runoff and capture soil
38Protecting soil terracing and intercropping
- Terracing level platforms cut into steep
hillsides - This staircase contains rain and irrigation
water
- Intercropping planting different crops in
alternating bands - Increases ground cover
- Decreases pests and disease
- Replenishes soil
39Terracing Carving steep hills into terraces to
retain water at each level and prevent soil
erosion from downhill runoff. Contour farming
plowing rows to follow the curve of gently
sloping land. Same benefits as terracing.
Terracing
40Protecting soil shelterbelts and reduced tillage
- Shelterbelts (windbreaks) rows of trees planted
along edges of fields - Slows the wind
- Can be combined with intercropping
- Conservation tillage reduces the amount of
tilling - No-till farming disturbs the soil even less
41Alley cropping rows of crops are planted
between a row of trees that provide fruit or
fuelwood and reduce Evaporation and wind blown
soil erosion Windbreaks - use rows of trees to
reduce wind erosion and help retain soil
moisture.
42Soil Degradation conventional tillage
- Conventional-tillage - fields often
- Plowed in the fall and left bare over
- winter. This leaves it vulnerable to
- Erosion, breaks soil structure
- Solution Conservation tillage
- Idea is to disturb the soil as little as
possible when - planting crops
- No-tillage- leave last years crop, use
- Seed injectors
- Minimum tillage - subsurface soil is
- loosened but not topsoil.
43- Water ManagementOver-watering a crop area will
result in erosion of soil and possible flooded
fields. - To counteract this farmers can plant crops native
to the area that do not require external
irrigation or employ minimal water techniques,
such as drip-irrigation - the process of only
watering the crops themselves by using a hose
with small holes at each crop.
44The changing face of agriculture
- 10,000 years ago, people in different cultures
began to raise plants for food and to domesticate
animals - Agriculture practice of raising crops and
livestock for human use and consumption - Cropland land used to raise plants for human use
- Rangeland land used for grazing livestock
- Land devoted to agriculture now covers 38 of
Earths land
45The changing face of agriculture
- Traditional agriculture uses human and animal
power - Hand tools, simple machines
- Polyculture different crops are planted in one
field - Industrial agriculture uses large-scale machines
and fossil fuels to boost yields - Also uses irrigation, fertilizers, and pesticides
- Monoculture planting a single, genetically
similar crop - More efficient but reduces diversity, is disease
prone - Narrows the human diet
- Used in industrial agriculture
46Industrialized Crop Production Causes Soil Erosion
- Industrialized agriculture, high-input
agriculture (intensive) produces 80 of worlds
food supply - Uses heavy equipment and large amounts of fossil
fuels, water, commercial fertilizers, pesticides,
and financial capital. - Primarily monocultures single crop in one area.
- Goal is to steadily increase crop yield, Ex Corn
47The effects of industrialized agriculture
- Industrial agriculture has allowed food
production to keep pace with population growth - But it has many bad environmental and social
effects - Benefits increases crop yields while reducing
pressure to develop natural areas for new farms - Drawbacks water, fossil fuels, fertilizers,
pesticides worsen pollution, erosion, and
desertification - Requires far more energy than traditional methods
- Displaces low-income farmers who cant afford the
technology, forcing them to move to cities
48Sustainable agriculture
- Suitable farmland is disappearing
- We must improve the efficiency of production
- It is better to raise animals and crops that
pollute less, require less fuels, and have less
impact on natural systems - Sustainable agriculture maintains healthy soil,
clean water, and genetic diversity - Treats agricultural systems as ecosystems
- Low-input agriculture uses smaller amounts of
- Pesticide, fertilizers, growth hormones,
antibiotics, water, and fossil fuels than
industrial agriculture