Fertilizer Elements in the Environment

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Fertilizer Elements in the Environment
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Fertilizer Elements in the Environment

• Concern about N and P in environment,
  particularly in water
• Nontarget effects Pollution

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Fertilizer Elements in the Environment

• Concern about N and P in environment,
  particularly in water
• Nontarget effects Pollution

Regulated
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Fertilizer Elements in the Environment
Runoff
CROP
Lake
Leaching
Groundwater
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Fertilizer Elements in the Environment
P
Runoff
N
CROP
Lake
Leaching
N
P
Groundwater
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N Losses through leaching and erosion
(particularly NO3-)

• Increasing over time in rivers and groundwater
  (e.g., Tivy, Table 15.4)
• Effects can be seasonal (highest in winter due to
  low uptake from plants)
• Nitrate problems more likely in shallow soils
  shallow wells more likely contaminated than deep
  wells

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Problems with N in water

• Wasted N and going to wrong site
• Contributor to eutrophication
• Problems in drinking water (EPA standards 10
  mg/L of nitrate N)

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Leaching of N depends on

• Type of N applied
• Soil type
• Soil depth (distance to water table)
• Amount of N applied
• Time when N is applied
• Rainfall
• Cattle or other animals
• Etc.

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P Losses more through erosion/surface runoff
rather than leaching

• P tends to be tied up in inorganic and organic
  compounds
• Often a limiting nutrient in aquatic ecosystems
• Industrial/urban sources also very important (not
  just ag)

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Problems with P in water

• Major contributor to eutrophication
• Eutrophication natural aging process of lakes
  and ponds
• Cultural eutrophication influence from humans
  when fertilizer accelerates the process

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Eutrophication affected by

• Amount of input (N, especially P) from
  fertilizer, sewage, detergents, etc.
• Distance from nutrient source to lake
• Depth and plant growth
• Temperature
• Water turnover rate
• Lake age

Natural factors
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Eutrophic Farm Pond
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P and Cultural Eutrophication

• P is especially limited in lakes
• Most P that accumulates in lakes is tied up in
  sediments and unavailable
• Added P stimulates plankton and circulates
  rapidly in plankton and aquatic food chains

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P and Cultural Eutrophication
Increased plant growth (phytoplankton, algae,
weeds)
Nutrient enrichment of lake
Increased P
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P and Cultural Eutrophication
Increased plant growth (phytoplankton, algae,
weeds)
Nutrient enrichment of lake
Increased P
High production (plants, fish, etc.)
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P and Cultural Eutrophication
Increased plant growth (phytoplankton, algae,
weeds)
Nutrient enrichment of lake
Increased P
High production (plants, fish, etc.)
Dead organisms, sedimentation
Decomposition, low O2
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Cultural Eutrophication cycle continues as long
as P is added
Increased plant growth (phytoplankton, algae,
weeds)
Nutrient enrichment of lake
Increased P
High production (plants, fish, etc.)
Dead organisms, sedimentation
Decomposition, low O2
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Is Cultural Eutrophication Reversible?

• Cycle broken if input is stopped or reduced
• Future limits imposed on amounts of P and N
  allowed in water
• Remediation (correction) and progress depend on
  several factors

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Factors in Eutrophication Potential
SOURCE Soil type Fert type Fert
amount Rainfall Erosion Plant uptake Animal mgmt
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Factors in Eutrophication Potential
SOURCE Soil type Fert type Fert
amount Rainfall Erosion Plant uptake Animal mgmt
LAKE Amount of input Size, depth Plant
growth Temperature Water turnover Lake age
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Factors in Eutrophication PotentialSome
Management Options
SOURCE Soil type Fert type Fert
amount Rainfall Erosion Plant uptake Animal mgmt
LAKE Amount of input Size, depth Plant
growth Temperature Water turnover Lake age
DISTANCE FROM SOURCE Condition of
watershed Weeds, grass can use excess fert.,
reduce erosion
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Limiting fertilizer impact in environment

• Reduced application amounts, alternative
  formulations
• Cultural practices (timing of applications,
  location of animal feeding and resting areas
  relative to runoff water, tillage practices to
  reduce erosion)
• Remediation and usage of excess fertilizer in
  watershed

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Concentrated animal operation point source for
N and P additions
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References

• Text, pp. 253-256.
• Begon, M., J.L. Harper, and C.R. Townsend. 1990.
  Ecology. Individuals, Populations and
  Communities. Blackwell Scientific Publications,
  Boston.
• Carroll et al. 1990. Chs. 6, 14.
• Tivy, 1992. Ch. 15, pp. 247-252.