Soil and Plant Nutrition

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Soil and Plant Nutrition
The Nation that Destroys Its Soil Destroys
Itself - President Franklin D.
Roosevelt

• Krystal, Caroline, Crystal

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Abstract

• It is important to know how to conserve soil in
  order to sustain agriculture. Soil texture and
  composition play an important role in determining
  which soil conditions optimize plant growth. Soil
  particles come in many different forms sand,
  silt, clay, etc. and result from the weathering
  of rocks. The type of soil helps determine the
  fertility of soil the most fertile being loam
  which has pores that are half air, and half water
  allowing for good aeration, drainage, and water
  storage. Inorganic components involve positively
  and negatively charged mineral ions that form a
  soil solution through cation exchange which can
  be absorbed by roots. In cation exchange, cation
  minerals attached to soil particles are displaced
  by H so that the minerals are available for soil
  solution while the H binds to the soil. Cation
  nutrients are better retained in soil than anion
  nutrients because soil particles are usually
  negatively charged. Organic components are mainly
  found within humus, composed of decomposing
  organisms. The humus provides crumbly soil with
  pores that can retain water and aerate soil while
  increasing cation exchange and act as a mineral
  reserve. In order to sustain agriculture, farmers
  use irrigation to provide ample water,
  fertilization to prevent nutrient depletion, pH
  adjustment to maximize growth conditions, erosion
  control to prevent nutrient runoff, avoiding soil
  compaction to ensure pores are not reduced, and
  phytoremediation to detoxicate contaminated
  soils. In conclusion, since soil contains all the
  nutrients necessary for plant growth, it is
  crucial to know various methods to prevent soil
  degradation.

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Soil a living finite resource

• Plants absorb nearly all water/minerals from
  upper layers of soil, therefore it is important
  to know how to preserve these layers. ?

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Soil Texture

• Texture depends on particle size (sand, slit,
  clay etc.)
• Particles come from the weathering of rock
• Soil horizons soil layers (top soil most
  important contains most nutrients/minerals)
• Water retained by attraction between negatively
  charged soil particles and water molecules
• Bigger soil particles more surface area for
  water retention
• Loams most fertile topsoil (poreshalf air/half
  water)

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Topsoil Composition

• Inorganic components (minerals)
• Binding ability (mineral to soil) depends on
  mineral charge (/-)
• Soil usually (-) therefore bind better with ()
  minerals less leaching
• Roots absorb minerals as soil solution made by
  cation exchange
• Cation Exchange process to make soil solution by
  displacing minerals attached to soil with H
• Cation exchange potential depends on adhesion
  sites and pH levels

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Topsoil Composition

• Organic components
• Includes organisms found in topsoil ? affect
  physical/ chemical soil properties
• Eg. Worms transport particles and help aerate
  soil
• Humus is a major organic part of topsoil
• Creates crumbly soil with pores that can retain
  water and aerate soil
• Increases cation exchange capacity
• Acts as mineral reserve

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Soil Conservation and Sustainable Agriculture

• If soil is fertilized, crops become renewable
  resource
• HISTORY LESSON Soil management helped establish
  first modern societies
• Sustainable agriculture includes different
  farming methods that are conservation minded,
  environmentally safe and profitable!

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Soil Conservation and Sustainable Agriculture
Irrigation

• Water is factor in plant growth ? bring water
  from other resources to replenish soil
• Limitation
• can destroy freshwater resources,
• 75 earths water resources used for agriculture
• Can lead to salinization (salt pile up when water
  evaporates)
• Drip irrigation requires less water, reduces
  saline

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Soil Conservation and Sustainable Agriculture
Fertilization

• Nutrient depletion is major cause of soil
  degradation
• Add fertilizer (minerals) to replenish soil
• Organic fertilizers contain decomposing organic
  material (manure, fishmeal, compost, etc.)
• Must be decomposed into inorganic nutrients that
  roots can absorb
• Gradual release of minerals, retained for longer
• Inorganic fertilizers chemical compounds
• Immediate release of minerals, easily lost by
  leaching
• Runoff can lead to algal populations oxygen
  depletion

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Soil Conservation and Sustainable Agriculture
Adjusting pH

• Affects cation exchange and chemical form of
  minerals (minerals tightly bound to soil
  minerals in unabsorbable form)
• Plants prefer slightly acidic soil (more H for
  cation exchange)
• Difficult to adjust (? one absorption, while ?
  another)
• pH lt 5, plant absorbs Al3 ? stops root growth,
  stop Ca uptake
• some plants secrete organic anions to bind to
  Al3 (make it harmless)

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Soil Conservation and Sustainable Agriculture
Controlling Erosion

• Major cause of soil depletion (nutrients carried
  away by wind/water)
• Prevention
• rows of trees (windbreaker), terracing hillside
  crops, cultivating in contour pattern
• Other crops good ground cover to protect soil
• No-till agriculture creating furrows to minimize
  soil disturbance (soil not turned ?fertilizers
  still underground)

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Soil Conservation and Sustainable Agriculture
Soil Compaction

• Soil Compaction squished soil that reduces pores
  less water, absorption, drainage, gas exchange
• Reduces root growth (hard to penetrate soil)
• Avoid Soil Compaction
• Dont farm wet soil,
• Use lighter equipment

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Soil Conservation and Sustainable Agriculture
Phytoremediation

• In industrial areas, toxic substances contaminate
  soil/water
• Soil remediation detox of contaminated soils
  (REHAB)
• Usually use nonbiological technologies
  (remove/store toxic soil in landfills) ? costly
  and disrupt landscape
• Phytoremediation non-destructive biotechnology
• Use other plants that have high affinity for
  toxic substances to harness those substances
  within the plant thus toxic chemicals removed by
  removing plant

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In Conclusion

• Soil properties (ability to retain water and
  minerals) determine the success of plant growth
• Thus it is important to know various methods to
  conserve soil (especially topsoil) which contains
  the nutrients necessary for growth

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