Plant Nutrient and Nutrient Cycle – SS2 Agricultural Science Lesson Note (First Term)

Lesson note at a glance

Subject: Agricultural Science
Class: SS2
Term: First Term
Topic: Plant Nutrient and Nutrient Cycle
Order: Topic 6 of 7 this term
Reading time: 5 min

Plant nutrients are classified into two, these include macronutrients and micronutrients.

MACRONUTRIENTS

These are mineral elements or nutrients required by crops in large quantities. Examples are nitrogen, phosphorus, potassium, magnesium, calcium and sulfur.

MICRONUTRIENTS OR TRACE ELEMENTS

These are mineral elements or nutrients required by crops in small quantities. Examples are Zinc, Copper, boron, molybdenum, Iron, Chlorine and Manganese.

Functions and deficiency symptoms of plant nutrients

SN	ELEMENT	FUNCTION	DEFICIENCY SYMPTOMS
1	Nitrogen	i. Aids plant’s growth and reproduction ii. Promotes vegetative and short-system growth iii. Excess Nitrogen delay maturation and fruiting iv. Promotes chlorophyll formation v. Necessary for synthesis of plant hormones	i. Stunted growth ii. Yellowing of leaves iii. Leaves tend to drop iv. Poor formation of fruits and flowers
2	Phosphorus	i. It aids enzyme reactions ii. It is a constituent of cell division iii. Increases soil resistance to diseases iv. Helps in ripening of fruits v. Help in root development and seed germination vi. Aids seed germination	i. Logging results in cereal crops ii. Stunted growth iii. Leaves turn purple and brownish iv. Poor root development Immature fruit drop
3	Potassium	i. Important constituent of plant tissues ii. Aids synthesis of carbohydrates iii. Activates various plant enzyme reactions iv. Promotes development of young plants v. Helps in nitrate uptake in the soil	i. Weak slender stems ii. Delayed growth iii. Premature loss of leaves iv. Brown colour at the margin of leaves
4	Calcium	i. Strengthens plant cells with calcium pectate. ii. Helps in translocation and storage of carbohydrates and proteins in seeds and tubers. iii. Necessary for normal growth of root tips. iv. It controls the toxicity of aluminium, manganese and sodium ions. v. It improves soil PH.	i. Causes stunting of the root system ii. Weak slender plants iii. Pale yellow colour of leaves
5	Magnesium	i. It is important in the synthesis of carbohydrates as it is a constituent of chlorophyll ii. It assists in the transportation of phosphate for fruit seed development iii. It enhances plant growth iv. It is required for normal cell division v. Necessary for synthesis of soil in plants	i. Chlorosis along leaf veins ii. Stunted growth Premature leaf fall

Nitrogen cycles

Nitrogen cycles refer to the circulation of certain nutrients like nitrogen, carbon and water in nature.

The nitrogen cycle is a natural way of regulating the amount of Nitrogen in the soil and air

Ways By Which Nitrogen Is Added To The Soil in Nitrogen Cycle

Direct fixation by lightning during rainfall.
Incorporation into the soil by free-living bacteria or non-symbiotic bacteria.
Nitrogen-fixing bacteria in the root nodules.
Decomposition of organic matter.
Application of Nitrogen fertilizer.
Ammonification.
Nitrification.

Soil can gain Nitrogen in the following ways:

Symbiotic Nitrogen Fixation
Electrical discharge
Non-symbiotic Nitrogen Fixation
Ammonification and Nitrification
Application or organic manure and 6. Nitrogen fertilizers

Ways by which nitrogen is lost from the soil are:

By Denitrification
Soil erosion
Leaching
Soil PH
Bush burning
Crop removal
Volatilisation
Oxidation reaction
Reduction reaction

Processes that lead to the formation of nitrate from organic matter in nitrogen cycle

Putrefaction: Delay of plant and animal remains into similar nitrogenous compounds by microorganisms
: Products from putrefaction reactions converted to simple amino compounds and animal
Immunization: Conversion of amino compounds and amines into ammonium compounds
Nitrification: Oxidation of ammonium compounds into nitrites and Nitrates

Carbon cycle

This involves the series of processes which contribute to the circulation of carbon in nature.

Explanation

Carbon Dioxide is removed from the air mainly by photosynthesis
Carbon is lost in the form of carbonates of calcium and magnesium through leaching and drainage.
The atmosphere gains carbon dioxide through
Burning of fuel like coal and wood
The action of volcanoes which releases carbon dioxide
The respiration of plants and animals
Death and decay and putrefaction of plants and animals
Diffusion of carbon dioxide from seas and other bodies of water

Importance of carbon cycle

Plant use carbon dioxide obtained from the air to manufacture their food during photosynthesis
Provision of carbon which is the essential building block of all organic matters
Organic matter which is made from carbon helps to replenish soil nutrients.

Water cycle

This is the continuous movement of water from the atmosphere to the earth and from the earth to the atmosphere.

The atmosphere receives water through:

Evaporation from oceans and land
Transpiration from plants
Breathing and respiration by plants and animals

Land receives water through:

Rainfall and precipitation
Infiltration and percolation

Forms in which water exists in the soil

Hygroscopic water
Capillary water
Gravitational water

Ways of conserving water in the soil

Stoppage or reduction of water-run-off
Addition of humus or organic mature
Removal of weeds to reduce transpiration and water loss
Mulching
Cover cropping
Contour ridging
Appropriate tillage
Strip cropping

Importance of water to crops

Water provides the medium for the absorption of minerals salts
It facilitates the transfer of nutrients to other parts of plants
It is an essential raw material during photosynthesis
Facilities enzymatic activities occurring in crop plant protoplasm
It is a constituent of protoplasm
It has a cooling effect on crops
It helps to sustain life
It helps in seed germination
It helps to maintain plant turgor or turgidity

ASSIGNMENT

The conversion of nitrates to nitrogen gas by certain bacteria is ___ (a) oxidation (b) reduction (c) nitrification (d) de-nitrification
Microbial delay of plant and animal remains into simpler nitrogenous compound is ___ (a) nitrification (b) putrefaction (c) leaching (d) burning
The washing away of soil nutrients down beyond the reach of the root is called ___ (a) erosion (b) mulching (c) leading (d) fertilization
The following are macronutrients except (a) boron (b) nitrogen (c) magnesium (d) calcium
Which of these is not a micro-element? (a) copper (b) zinc (c) boron (d) potassium

6(a) Differentiate between macro and micronutrients

(b) List three factors influencing nutrient availability in the soil

7(a) State three functions of Nitrogen to plants

(b) State three importance of organic matter in Agricultural

This term's Agricultural Science topics

SS2 First Term · 7 topics

Plant Nutrient and Nutrient Cycle – SS2 Agricultural Science Lesson Note (First Term)

Lesson note at a glance

Functions and deficiency symptoms of plant nutrients

Nitrogen cycles

Ways By Which Nitrogen Is Added To The Soil in Nitrogen Cycle

Processes that lead to the formation of nitrate from organic matter in nitrogen cycle

Carbon cycle

Importance of carbon cycle

Water cycle

Forms in which water exists in the soil

Ways of conserving water in the soil

Importance of water to crops

This term's Agricultural Science topics

Lesson Notes for Other Classes

Get the complete SS2 First Term lesson notes

Plant Nutrient and Nutrient Cycle – SS2 Agricultural Science Lesson Note (First Term)

Lesson note at a glance

Functions and deficiency symptoms of plant nutrients

Nitrogen cycles

Ways By Which Nitrogen Is Added To The Soil in Nitrogen Cycle

Processes that lead to the formation of nitrate from organic matter in nitrogen cycle

Carbon cycle

Importance of carbon cycle

Water cycle

Forms in which water exists in the soil

Ways of conserving water in the soil

Importance of water to crops

This term's Agricultural Science topics

First Term Agricultural Science Lesson Notes for Other Topics

Lesson Notes for Other Classes