12 - Necessary Nutrients

12.1 Soil Nutrients and Fertilizer

What is soil?

• Dirt is MISPLACED soil• Soil is a major source of plant

nutrients– What factors make a “good” soil?

• Physical properties• Biological properties • Chemical properties

Fertilizers

• Fertilizers are substances rich in plant nutrients and used to increase the fertility of soils.

• They include– Nitrogen (N)– Phosphorus (P)– Potassium (K)

• Fertilizers are labeled with an N-P-K ratio such as 10-10-10

Concerns with Fertilizers• Run-off is water that runs off fields an

carries nitrates with it. • Runoff water ends up in streams, lakes

and other water bodies.• Runoff can contaminate drinking water• Nitrates cannot be “seen” in the water but

through a simple test the water can be tested for nitrates.

• Run-off can be decreased by carefully regulating the amount of fertilizer put on fields.

Soil Testing Lab• Complete the Part A and Part B of the

procedures• Complete the Individual analysis questions

on page 151 after you have completed the procedures.

12.2 Dirty Differences

Soil• Is a complex mixture of living and non-

living matter that contains:– Air– Water– Minerals– Particles– Organic Material– Organisms such as bacteria, fungi, worms and

insects.

SOIL IS THE FOUNDATION OF THE ECOSYSTEM!

Soil Structure• Soils form from rock and very greatly

depending on the age of the soil and the climate of the region

• Young soils are thin and rocks and they ability to support plant growth is limited to small hearty plants such as grasses and wildflowers.

• Mature soils built up over time, as plants grow and die they break down the rock and leave behind organic material

Soil Profile• Mature soils consist of layers:

– O = Organic material- A = Top soil

- Dark in color- High in humus

- B = Sub Soil- Originated from the rock- Leached nutrients- Some roots of large plants

- C = Parent Material

Nutrients• Macronutrients

– N– P– K– S– Mg– Ca

• Micronutrients– Cl– Fe– B– Mn– Zn– Co– Mo– Ni

-Create your own mnemonic device

Soil Nutrients• Nitrogen

– Is a part of every living cell– Stimulates above ground plant growth and is

responsible for rich green color– Can only be absorbed from plants when it is

present in the soil in the form of nitrate compounds

– Nitrates dissolve easily in water, there for move in and out of soil easily

Soil Nutrients• Phosphorus

– Essential for the growth of new seedlings– Promotes early formation of roots, seeds and

fruits– Cannot be absorbed by plants unless it is

present in the soil as phosphate compounds

Soil Nutrients• Potassium

– A catalyst necessary for plant metabolism.– Strengthens a plant’s resistance to disease

Calcium• Calcium is present in the cytoplasm at

levels that would indicate that it is a micronutrient, ~0.1 µM, in order to prevent interference with the high levels of P.

• Small fluctuations in Ca levels in the cytoplasm are part of signaling mechanisms for environmental stress.

• Function: Structural, in the cell walls of shoots and roots.

Magnesium• The central ion in chlorophyll molecule,

accounts for <25% of total plant Mg • Mg in the cytoplasm is related to enzyme

activation: for example, the substrate for ATPases is MgATP.

• Additional Mg is present in the cell wall • Deficiency: Grass tetany for livestock

Sulfur• Essential to growth and physiological

functioning• Needed to develop amino acids cysteine

and methionine

Law of Minimum• Created by Justus von Liebig• Yield is proportional to the amount of the

most limiting nutrient, whichever nutrient it may be.

Calculation #1• You have a 5,000 square foot yard• Need 5 lbs of N per 1,000 feet• You have 100 lbs of 22-5-10 fertilizer

• How many pounds do you need to use?

Calculation #2• You have a 4,000 square foot yard• Need 5 lbs of N per 1,000 feet and 2 lbs of

K for every 1,000 feet• You have 100 lbs of Urea 64-0-0 and

Green Zone 5-5-20

• How much do you need to use of each fertilizer?

Homework Problem• You have 2.5 acre yard• An acre has 43,560 square feet

• Need:– 5 lbs of Nitrogen for each 1,000 sq. feet– 1 lbs of Phosphate for each 1,000 sq. feet– 5 lbs of Potassium for each 1,000 sq. feet

• Pick your fertilizers:– Kevin’s Manure 64-0-0 --Trey’s Triple 10-10-10– KU Basketball 0-0-15 --John’s Jungle 0-51-0

12.3 Soil Components and Properties

Soil properties• Porosity

– A measure of the volume of space the lies in the openings between soil particles.

Permeability• The rate at which fluids can move though

the soil

Water Retention• The amount of water the soil can absorb.• Which soil type would have the ability to

hold more water, sand or clay?• Why?

Soil Lab• Complete the procedure and analysis

questions on page 156 and 157.

Ag Ed Tube• Soil Quality, Conservation and Food Produ

ction

12.4 Mineral Mania