Soil Fertility

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Soil Fertility

• Inorganic fertilizers
• Most developed in the 1940s
• Ammonium nitrate
• Superphosphate
• Muriate of potash
• These are often pure (do not contain
  micronutrients)
• These are often concentrated (therefore they are
  cheaper to transport and apply)

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Soil Fertility

• Nitrogen is often the most limiting nutrient in
  soils
• Nitrogen applied in excess causes reduced
  flowering and fruiting and greater vegetative
  (leafy) growth

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Soil Fertility

• Fertilizer analysis
• Percentage (by weight) of the available Nitrogen
  (as N), Phosphorus (as P2O5) and Potassium (as
  K2O)
• Ex 5105
• 5 N
• 10 P
• 5 K
• 80 in the bag is inert material!

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Soil Fertility

• High analysis NPK percentage gt 30
• Ex 30 lbs. of N,P,K in a 100 lb. bag of
  fertilizer
• Less costly (dont pay for a lot of filler, but
  tricky to apply)
• Low analysis NPK percentage lt 30
• more costly due to weight in transport but easier
  to apply

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Soil Fertility

• Fertilizer ratio
• The proportion of the three major elements
• Ex 5105 121 ratio

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Soil Fertility

• N-recommendations (in lbs./acre)
• If the soil test indicates that you need to apply
  100 lbs. of N per acre, how many pounds of a
  201010 fertilizer would you need?
• 20 X 100 lbs.
• 0.20 X 100 lbs.
• X 100 lbs./0.20
• X 500 lbs.

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Soil Fertility

• Now you probably dont have a garden that is an
  acre in size.
• Ex If your garden is 20 x 20 400 ft2

1 acre 43,560 ft2
Your garden plot
20
208.5
20
208.5
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Soil Fertility

• 500 lbs X lbs.
• 43,560ft2 400 ft2
• 43,560 X 200,000
• 200,000
• 43,560
• X 4.59 lbs. of fertilizer per 400 sq. feet

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