Download Soil pH

Unit 5- Soil Science
Soil Fertility
Nutrient Needs for Plant Growth
Plants need nutrients in order to grow properly.
• Plants receive most of the nutrients that they
need from the growing media.
• Plant nutrients can be divided into two
groups, macronutrients and
micronutrients.
Nutrient Needs for Plant Growth
Macronutrients are those elements that are
needed by the plant in the largest amount.
• nitrogen (N)
• phosphorus (P)
• potassium (K)
• calcium (Ca)
• magnesium (Mg)
• sulfur (S)
Primary Nutrients
Nitrogen, phosphorus, and potassium are
considered primary nutrients.
• Nitrogen-produce green leafy growth
• Phosphorus- flowers and fruit production
• Potassium- provide disease resistance
Nutrient Needs for Plant Growth
Micronutrients- nutrients needed in smaller
amounts by the plants, but are still essential
to plant growth.
• boron (B)
• copper (Cu)
• chlorine (Cl)
• iron (Fe)
• manganese (Mn)
• molybdenum (Mo)
• zinc (Zn)
Nutrient Deficiency
A soil test can be performed on the soil to
determine which nutrients are present or
deficient (absent or lacking).
When nutrients are deficient in the soil, the
plant growth is adversely affected.
Signs of Nutrient Deficiency
Oftentimes, plants visibly show a nutrient
deficiency by turning colors.
• When nitrogen is deficient in the soil, a
plant’s older leaves will start to turn yellow
(chlorosis) and eventually die.
• A plant will show purpling in the stem or
leaf when phosphorus is deficient in the
soil.
Soil pH
Soil pH measures the amount of acidity or
alkalinity in the soil. It is based on the
amount of hydrogen ions present in the
soil.
Nutrient availability is influenced by the pH
of the soil.
Soil pH
Soil pH can range from
1-14.
• pH readings of 1-6
are acidic
• pH readings of 8-14
are alkaline or basic
• pH reading of 7 is
neutral
Amending Soil pH
A soil test can be done to determine the pH
of the soil and amendments can be added
to modify the pH.
• To raise the pH, limestone can be added
to the soil.
• To lower the pH, Sulfur is added to the
soil.
Fertilizer
A fertilizer is any material that is provided to
plants to supply the nutrients needed for
plant growth.
Fertilizers vary in the components they
contain, the way they are applied, and the
function they serve.
Fertilizer Analysis
The fertilizer analysis states the
percentage of primary nutrients (nitrogen,
phosphate, and potash) present in the
fertilizer.
The analysis is written as 3 numbers, for
example, (15-10-26). The numbers,
always in this order, represent the percent
of nitrogen, phosphorus, and potash,
present in the fertilizer.
Fertilizer Analysis
Example: A fertilizer with an analysis of
15-10-6
has 15% nitrogen,10% phosphate, and 6%
potash.
Fertilizer analyses do not equal 100%. The rest
of the fertilizer composition would be some
micronutrients and other filler materials.
Complete/Incomplete Fertilizers
If a fertilizer contains all three primary
nutrients, it is called a complete fertilizer.
If a fertilizer is lacking any of the three
primary nutrients, it is an incomplete
fertilizer.
Fertilization Plan
When growing plants, it is important to use
the right type of fertilizer for the end result.
Example
Fertilizer
Result
High Nitrogen
Green Foliage
High Phosphorus
Flowering
Root stimulation
Fertilization Plan
It is equally important to time the fertilizer
in a way that is most beneficial to the
plants.
The grower should also consider the
application method that eliminates the
most waste, making the fertilizer most cost
effective and least harmful to our
environment.
Fertilizer Plan
• Liquid form- sprayed directly onto the
foliage
• Granular- slow release fertilizer; slowly
dissolves over a period of time