UNIT: Fertilizer

JOB: Introduction to fertilizers.

SITUATION:

OBJECTIVES:
    1. To develop the students understanding of what a fertilizer is.
    2. To develop the students understanding of sources of fertilizers.

MOTIVATION
    1. Discuss what a fertilizer is.
    2. Discuss the types of fertilizers and where fertilizers come from.

STUDY GUIDES:

    1. How many elements are required for plants to grow normally?

    2. Well-fed plants will provide what for animals and humans?

    3. What is a fertilizer?

    4. What will fertilizers do for plants?

    5. What are the two types of fertilizers?

    6. How are commercial fertilizers developed?

    7. What are some examples of natural fertilizers?

    8. Has the usage of commercial fertilizers increased or decreased since the early 1900’s?

    9. What is a grade when dealing with fertilizers?

    10.  What is a carrier?

    11.  What are mixed goods?

    12. What is a filler?

    13.  What are conditioners?

    14.  What are the average compositions on a dry weight basis for organic materials used as fertilizers?

    15.  What is the recommended application rate for organic materials on dryland crops?

    16.  Are manures high or low-grade fertilizers?

    17.  What must occur for the release of N, P, and S to plants?

    18.  What are some positive aspects of organic additions to soils?

    19.  What are some negative aspects of organic additions to soils?

    20.  What are some recommended practices for application of fertilizers?

    21.  What is the best time for fertilizer application?

    22.  What are some types of applications?

    23.  What is the Law of Diminishing Returns?
 

 
REFERENCE: Lecture Notes for Introductory Soil Science, K.A. Barbarick, pg. 215-226, chapter 20

ANALYSIS:

1. How many elements are required for plants to grow normally?
At least 16 elements are required for plants to grow normally.

2. Well-fed plants will provide what for animals and humans?
Well-fed plants provide better nutrition for animals and humans who consume the crop.

3. What is a fertilizer?
Fertilizers are materials, which supply one or more of the essential plant food elements.

4. What will fertilizers do for plants?
Fertilizers help plants grow and develop.

5. What are the two types of fertilizers?
Natural/Organic and Commercial.

6. How are commercial fertilizers developed?
Commercial fertilizers are inorganic.  Commercial fertilizers are mixtures of plant food elements with inert carriers.

7. What are some examples of natural fertilizers?

Guano-manure from sea birds

Leave and residues from other plants

Tankage

Blood and other animal materials

Animal manure

Effluent

Night soil-human waste

8. Has the usage of commercial fertilizers increased or decreased since the early 1900’s?
There has been an increased usage of commercial fertilizers since the early 1900’s.

9. What is a grade when dealing with fertilizers?
Grade (guarantee) is the required minimum analysis of % total N, citrate-soluble P expressed as P2O5, and water-soluble K expressed as K2O.

10.  What is a carrier?
Carriers are fertilizers which are single, unmixed minerals or compounds.

11.  What are mixed goods?
Mixed goods are combinations of materials with N, P, and K.

12. What is a filler?
Filler is the inert material used to obtain the proper weight and guarantee of a mixed fertilizer.

13.  What are conditioners?
Conditioners are preservatives or drying agents that are added to fertilizers to maintain their physical integrity.

14.  What are the average compositions on a dry weight basis for organic materials used as fertilizers?

Horse

1.5-2.0% N
0.1-0.5% P
1.0-1.5% K

Steer

3.0-3.5% N
0.1-0.5% P
2.0-2.5% K

Dairy

2.5-3.0% N
0.1-0.5% P
2.0-2.5% K

Swine

2.0-2.5% N
0.5-1.0% P
1.0-1.5% K

Sheep

4.0-4.5% N
0.5-1.0% P
2.5-3.0% K

Poultry

2.5-3.5% N
0.5-1.0% P
1.5-3.0% K

Sewage sludge

1.0-10.0% N
0.5-3.0% P
0.5-1.0% K

15.  What is the recommended application rate for organic materials on dryland crops?
Three dry tons per acre.

16.  Are manures high or low-grade fertilizers?
Manures are low-grade fertilizers

17.  What must occur for the release of N, P, and S to plants?
Mineralization

18.  What are some positive aspects of organic additions to soils?

Improves soil structure

Increases water holding capacity

Adds plant nutrients (N,P,S, and micronutrients)

19.  What are some negative aspects of organic additions to soils?

• Adds soluble salts
• Adds weed seeds
• Could add pathogens
• Could add toxic chemicals, trace metals, or excess N to soils


20.  What are some recommended practices for application of fertilizers?

• Broadcast-Fertilizer is spread evenly over the soil surface.
• Banding-Fertilizer is placed in a concentrated zone.
• Liquid distributors
• Aircraft
• Fertigation-Fertilizer is applied with irrigation H2O.  It is commonly done with sprinkler and trickle irrigation

21.  What is the best time for fertilizer application?
It is usually best to apply fertilizer to meet the changing demands of the plants.

22.  What are some types of applications?

• Apply P, K to annual row crops in concentrated bands.
• Perennial crops use broadcast or liquid application.
• Use foliar spray of 2% FeSO4 to apply Fe.
• Add Fe in chelated form and maintain acidic conditions in hydroponic.


23.  What is The Law of Diminishing Returns?
The point at which there is no further response to increasing amounts of a nutrient.