The document discusses the criteria for classifying plant nutrients as essential. It notes that while over 100 elements can be absorbed by plants, only 16 are considered essential based on criteria developed by Arnon and Stout. To be essential, a nutrient must be necessary for growth and reproduction, not replaceable by another element, and directly involved in plant metabolism. Nutrients are also classified as macro or micronutrients based on the amount required by plants. The key essential nutrients - carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium and others - are also outlined.

1. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Plant Nutrients: Criteria for Nutrient Essentiality
Essential Plant Nutrients: Criteria for
Nutrient Essentiality
Krishna Aryal
Asst. Professor (Soil Science)
Krish.aryal2014@gmail.com
1

2. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Plant Nutrients: Criteria for Nutrient Essentiality 2
• In the nature there are nearly one
hundred and three elements.
• Most of the mineral elements present in
the soil enters plants through roots.
• Analysis of ashes of different plants
reveals that around 90 elements are
taken in by the plants
• All the 90 elements are not present in all
plants. Out of them only 16 elements are
present( some cites 17).

3. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Plant Nutrients: Criteria for Nutrient Essentiality 3
Criteria for Nutrient Essentiality
• Daniel Arnon and Perry Stout (1939) carried out experiment on the
essentiality of nutrients in tomato.
• Laid down the basic requirements to distinguish the elements which are
essential from those which may be taken in by the plants but are not
essential
• For a plant nutrient to be essential it should fulfill the following criteria:

4. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Plant Nutrients: Criteria for Nutrient Essentiality 4
• The element must be necessary for supporting normal growth and
reproduction. In the absence of the element, the plants do not
complete their life cycle.
• The requirements of the element must be specific and not replaceable
by another element. In other words, deficiency of any one element
cannot be met by supplying some other element.
• The element must be directly involved in the metabolism of the plant.
• Based on this, 16 elements have shown to be generally essential to
plants

5. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Plant Nutrients: Criteria for Nutrient Essentiality 5
Classification of plant nutrients
Nutrients
Essential Nutrients Non-Essential/ Beneficial Nutrients
( Si, Na, I, V, Co, Ni, Se )
Macro Nutrients Micro Nutrients
( B, Fe, Zn, Cu, Cl, Mn, Mo )
Non mineral Nutrients
( C, H, O )
Mineral Nutrients
Primary Nutrients
( N, P, K )
Secondary Nutrients
( Ca, Mg, S )

6. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Plant Nutrients: Criteria for Nutrient Essentiality 6
Carbon (C)
Hydrogen(H)
Oxygen (O)
Nitrogen (N)
Phosphorus (P)
Potassium (K)
Calcium (Ca)
Magnesium (Mg)
Sulphur (S)
Macro nutrients
Required by the
plants in relatively
large amount; >
0.1% of dry plant
tissue
Boron (B)
Iron (Fe)
Zinc (Zn)
Copper (Cu)
Chlorine (Cl)
Manganese (Mn)
Molybednum (Mo)
Micro nutrients
Required by the
plants in relatively
less amount; <
0.1% of dry plant
tissue
a. On the basis of amount required

7. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Plant Nutrients: Criteria for Nutrient Essentiality 7
Macronutrients are also classified as :
Carbon (C)
Hydrogen(H)
Oxygen (O)
Structural nutrients
(95-99% of fresh
plant tissue)
Non-mineral
nutrients
Obtained from air and
water
Nitrogen (N)
Phosphorus (P)
Potassium (K)
Primary nutrients
(required in large
quantities )
Calcium (Ca)
Magnesium (Mg)
Sulphur (S)
Secondary nutrients
(required in intermediate quantities )

8. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Plant Nutrients: Criteria for Nutrient Essentiality 8
• About 95-99.5% of fresh plant tissue is made up of C, H & O. only 0.5-
5.0% remains as ash after tissue is dried and burned.
• Plant growth is not seriously retarded by C, H and O as long as water is
available & CO2 in air is plentiful

9. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Plant Nutrients: Criteria for Nutrient Essentiality 9
Beneficial nutrients:
• Helps to optimize the growth and development of plants but they are not
essential for growth.
• Essential for particular crop, but not for all crop
Eg:
Si (paddy)
Na (sugarbeet)
V (Asparagus)
I (Spinach)
Co (Grasses)
Ni (Legumes)

10. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Plant Nutrients: Criteria for Nutrient Essentiality 10
b. On the basis of mobility of nutrient in soil
i. Mobile nutrients (5)
• highly soluble, remains & moves in soil solution & these are not adsorbed
on clay complexes.
• So greater availability to plant if presents.
• But subjected to leaching along with percolating water.
• Eg. NO3-, SO42-,BO32-, Cl- , Mn+2

11. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Plant Nutrients: Criteria for Nutrient Essentiality 11
ii. Less mobile nutrients (5)
• Soluble, remains and moves along the soil solution but are adsorbed to
clay complex
• NH4+, K+, Ca2+, Mg2+, CU2+
• Moves short distances
iii. Immobile nutrients
• Highly reactive & get fixed to the soil
• H2PO4-, HPO4– Zn ++
• Low plant availability;
• High application rates allow for uptake by root interception (eg. P);

12. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Plant Nutrients: Criteria for Nutrient Essentiality 12
C. On the basis of mobility within plant
i. Mobile nutrients:
• Can translocate from older leaves to the younger leaves when nutrient
supply is reduced
• Deficiency symptoms are manifested on the older leaves.
• N, P, K, Mg, Cl, Mo
ii. Immobile nutrients:
• Cannot translocate from older leaves to the younger leaves when nutrient
supply is reduced
• Deficiency symptoms appear first on the younger leaves.
• Ca, B, Fe, Mn, Cu, Zn, S

13. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Plant Nutrients: Criteria for Nutrient Essentiality 13
Elements Form absorbed Concentration in
plants
Soil pH
availability
Primary sources
Structural nutrients
Carbon(C) CO2 45% - Carbon dioxide in
air
Hydrogen (H) H2o 6% - Water
Oxygen (O) CO2 , O2, H2o 43%- 45% - Water , air
Primary nutrients
Nitrogen (N) NO3
-, NH4
+ 1-6% 6-8 Organic matter,
atmosphere
Phosphorus (P) H2PO4
-, HPO4
2- 0.05-1.0% 6.5-7.5 & 8.5-
10
Soil minerals ,
organic matter
Potassium (K) K+ 0.3-6% 6-10 Soil minerals
Forms of essential nutrients absorbed by plants

14. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Plant Nutrients: Criteria for Nutrient Essentiality 14
Elements Form absorbed Concentration in
plants
Soil pH
availability
Primary sources
Secondary nutrients
Calcium (Ca) Ca2+ 0.1-3% 7-10 Soil minerals, limestone
Magnesium (Mg) Mg2+ 0.05-1.5% 7-10 Soil minerals, limestone
Sulfur (S) So4
2- 0.05-1.5% 6-10 Organic matter, rain water
Micronutrients
Iron (Fe) Fe2+, fe3+ 100-1000 Ppm Less than 6 Soil minerals
Manganese (Mn) Mn2+ 5-500 Ppm Less than 6.5 Soil minerals
Copper(Cu) Cu2+ 2-75 Ppm 5-7 Soil minerals , organic
matter
Zinc (Zn) Zn2+ 5-1000 Ppm 5-7 Soil minerals, organic
matter
Boron (B) H3Bo3 2-75 Ppm 5-7 Organic matter
Molybdenum (Mo) MoO4
2- 0.01-10 Ppm 7-10 Soil minerals, organic
matter
Chlorine (Cl) Cl- 0.05-3% - Rain water

15. Institute of Agriculture and Animal Science (IAAS)
Prithu Technical College
Deukhuri, Dang
SSC-121 Essential Plant Nutrients: Criteria for Nutrient Essentiality 15