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Organic Fertilizer Qualities

This table shows the qualities of various natural substances commonly used to fertilize organic vegetable gardens.  The information is taken from Oregon State University Extension Service.

Fertilizer

Nitrogen %

Phosphorus

Potassium

When it is available to plants

Time that it’s effective

Bat Guano

5.5-8

4-8.6

1.5

Medium to Fast

Blood Meal

12.5

1.5

0.6

Medium

6-8 weeks

Bone meal (steamed)

.7-7

18-24

0

Slow to medium

2-4 months

Compost

1.5-3.5

.5-1

1-2

Slow

Cottenseed meal

6-Apr

2.5-3

1.6

Slow to medium

4-6 months

Feather meal

15

0

0

Slow

4-6 months

Fish emulsion

5

1

1

Fast

2 weeks

Fish meal – dry

10

4-6

0

Medium

4-6 months

Kelp

1

0.5

4-13

Slow

4-6 months

Mushroom compost

.5-.8

40-55

.5-.8

Slow

Phosphate, colloidal

0

17-25

0

Slow

3 years

Phosphate, rock

0

17-30

0

Very slow

5+ years

Seaweed

0-2

0

.5-1

Fast

Worm castings

1.5

2.5

1.3