Criteria for nutrient essentiality

Arnons and stout criteria for nutrient essentiality

1. Essential Plant Nutrients: Criteria for Nutrient Essentiality Krishna Aryal Asst. Professor (Soil Science) [email protected] 1

2. 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. 3 Criteria for Nutrient Essentiality • Daniel Arnon and P erry 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. 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. 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. 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. 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. 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. 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. 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 . NO 3 -, SO 4 2-,BO 3 2-, Cl- , Mn+2

11. 11 ii. Less mobile nutrients (5) Soluble, remains and moves along the soil solution but are adsorbed to clay complex NH 4 +, K+, Ca 2 +, Mg 2 +, CU 2 + Moves short distances iii. Immobile nutrients • Highly reactive & get fixed to the soil • H 2 PO 4 -, HPO 4 – Zn ++ • Low plant availability ; • High application rates allow for uptake by root interception ( eg . P);

12. 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 D eficiency symptoms appear first on the younger leaves. Ca , B, Fe, Mn , Cu, Zn, S

13. 13 Elements Form absorbed Concentration in plants Soil pH availability Primary sources Structural nutrients Carbon(C) CO 2 45% - Carbon dioxide in air Hydrogen (H) H 2 o 6% - Water Oxygen (O) CO 2 , O 2 , H 2 o 43 %- 45% - Water , air Primary nutrients Nitrogen (N) NO 3 - , NH 4 + 1-6% 6-8 Organic matter, atmosphere Phosphorus (P) H 2 PO 4 - , HPO 4 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. 14 Elements Form absorbed Concentration in plants Soil pH availability Primary sources Secondary nutrients Calcium (Ca) Ca 2+ 0.1-3% 7-10 Soil minerals, limestone Magnesium (Mg) Mg 2+ 0.05-1.5% 7-10 Soil minerals, limestone Sulfur (S) So 4 2- 0.05-1.5% 6-10 Organic matter, rain water Micronutrients Iron (Fe) Fe 2+ , fe 3+ 100-1000 Ppm Less than 6 Soil minerals Manganese (Mn) Mn 2+ 5-500 Ppm Less than 6.5 Soil minerals Copper(Cu) Cu 2+ 2-75 Ppm 5-7 Soil minerals , organic matter Zinc (Zn) Zn 2+ 5-1000 Ppm 5-7 Soil minerals, organic matter Boron (B) H 3 Bo 3 2-75 Ppm 5-7 Organic matter Molybdenum (Mo) M o O 4 2- 0.01-10 Ppm 7-10 Soil minerals, organic matter Chlorine (Cl) Cl - 0.05-3% - Rain water

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