This document provides information about sulphur as a secondary nutrient for plants. It discusses sulphur's characteristics, role in plant growth, sources in soil and fertilizers, transformations and cycling in soil, deficiency symptoms, and importance for Indian agriculture. Sulphur is essential for plant protein synthesis and other biological compounds. It is present in soil organic matter and various minerals and fertilizers. Microbial activity drives its transformation between organic and inorganic forms.

2. SULPHUR
Presentation
on
Master of Science in Agriculture
(Soil Science)
Submitted To:
Dr. H.C. Dixit
Head & Professor
Submitted by:
Chetan Kumar Dotaniya
M.Sc. Soil Science
Department of Soil Science and Agricultural Chemistry
College of Agriculture,
Nehru Mahavidhalya Lalitpur,
Bundelkhand University Jhansi UP

3. INTRODUCTION
 Calcium, magnesium and sulphur are considered
as secondary nutrients for plants; however, they
play no secondary role in plant nutrition.
 They are just as essential for plant nutrition as
any of the other 14 essential plant nutrients.
 Although, secondary nutrients are needed in
lesser amounts than that of primary nutrients but
they are important for plants.

4. INTRODUCTION
 Many factors can affect the availability of these
three nutrients to plants.
 The best estimates of their availability can be
determined by soil analysis or a combination of
soil and plant analyses.
 However, field observations and deficiency
symptoms are also important diagnostic tools.

5. INTRODUCTION
 Sulphur is an essential nutrient for the plants
was so far discovered by Salon Horstmas.
 Sulphur is a major constituent of organic matter
and involved in enzymic processes.
 Sulphur is essential in formation of plant protein
because it is a part of certain amino acids.
 It is an essential constituent of several other
biologically active compounds such as vitamins,
lipoic acid, acetyl coenzyme A, ferrodoxin and
glutathione.

6. CHARACTERSTICS OF SULPHUR NUTRIENT
 Symbol – S
 Atomic number- 16
 Atomic weight- 32.065
 Specific gravity at 20oC- 2.07
 % proportion of earth crust- 0.10%
 Ionic forms absorbed by plants- SO4
2-,SO2, SO3
2-
 Approximate conc. in dry weight of plant- 0.1-
0.4%
 Mobility in plants- Relatively immobile

7. ROLE OF SULPHUR IN PLANTS GROWTH
 Component of amino acids (methionine,
cysteine).
 Constituent of coenzymes and vitamins.
 Responsible for pungency and flavour (onion,
garlic, mustard).
 It also enhances the oil synthesis in oil seed
crops.
 Though it is responsible for protein synthesis, it
is an important content for pulse crop.
 Involved in the formation of Chlorophyll and
promotes nodule formation.
 It increases root growth and stimulate seed
formation

8. SOURCE OF SULPHUR NUTRIENT IN PLANTS
 Sulphur consist of earth crust about 0.06%, it occurs
as sulphide in igneous and sedimentary rocks.
 The S-bearing mineral in rocks and soils are
Gypsum (CaSO4.2H2O), Epsomite (MgSO4.7H2O),
Mirabilite (Na2SO4.10H2O), Pyrite (FeS2), Sphalerite
(ZnS), Chalcopyrite (CuFeS2), Cobaltite(CoAsS) and
Galena(PbS).
 Atmosphere is an another source of Sulphur.
 A considerable amount of Sulphur is released by the
breakdown of the soil organic matter that is 20-30
kg SO3/ha.

9. SOURCE OF SULPHUR NUTRIENT IN PLANTS
 Sulphur content is also there in organic
fertilizers.
 Cow and Pig manure contains 1.8 kgSO3/t,
compost contains around 3.8 kgSO3/t and poultry
manure contains around 8.3 kgSO3/t.
 Some mineral fertilizers also have sulphur
content in the form of sulphate, elemental
sulphur and liquid form.
 Acid Rain also provides sulphur.

10. Fertilizer S %
Sources of sulphate SO4
2-
Nitrate Sulphate 5-14
Ammonium sulphate 24
Simple superphosphate 12
Ammonium sulphate-phosphate 14-20
Calcium sulphate 14-18
Potassium sulphate 16-22
Calcium-Magnesium sulphate 22
Magnesium sulphate (Epsom) 18
Magnesium sulphate (Kiesirite) 22
Sources of elemental sulphur
Elemental sulphur 85-100
Triple superphosphate granulated with
sulphur
18
Sulphur Bentonite 85-90
Table:- Mineral Fertilizers having per cent Sulphur Content
Source:- Arun Katyayan(2012)

11. LOSSES OF SULPHUR
 Loss of sulphur by crop plants.
 Loss of sulphur by erosion.
 Loss of sulphur by weeds.
 Loss of sulphur through leaching.
 Loss of sulphur by volatilization.

12. DEFICIENCY SYMPTOMS
 Sulphur deficiency symptoms first appear on
younger leaves, because S is immobile nutrient.
 The younger leaves become pale or chloratic.
 The stem and leaf petioles become brittle and
may collapse.
 Plants looks withering.
 Different plants have different deficiency
symptoms like shortened panicle in Rice, delayed
flowering in soybean, leaves become narrow and
short in wheat and less oil content in mustard etc.

13. FORMS OF SULPHUR NUTRIENT IN SOIL
 Sulphur is present in the soil in both
organic and inorganic form.
 Sulphur can be broadly grouped into five
forms, viz. Organic S, inorganic S, soluble S
insoluble S and adsorbed S.
 Among of these forms Organic Sulphur is
most important i.e. 5 to 98% of available S
in Indian soils.

14. TRANSFORMATION/ MINERALIZATION OF SULPHUR
 All the forms of Sulphur are not available to the crop
plants, therefore, its mineralization is essential to
convert unavailable form of S into available form.
 This transformation/mineralization depends upon
several factors, these factors are:-
 Microbial activity
 Effect of soil temperature
 Effect of soil pH
 Effect of soil moisture content
 Effect of cations on the mineralization of S

15. TRANSFORMATION/ MINERALIZATION OF SULPHUR
 Transformation of elemental sulphur to SO4
2- form
was necessary for sulphur to be available for crop
uptake (Singh, 1988).
 The oxidation was faster in coarse textured soils and
is completed in 3-4 weeks.
 Sulphur transformations in soil are considered to
result primarily from microbial activity which
involves process of mineralization, immobilization,
oxidation and reduction and the microbes involved
are Thiobacillus, Chlorabium and Desulfotomaculam.
 The biogeochemical transformation of sulphur has
been formulated by Vernadski (1927).

16. SULPHUR CYCLE
 Sulphur from all the sources changes in the
sulphate or available form of sulphur.
 The crop plant uptake that available S and
some of this lost due to leaching and a
considerable part losses to atmosphere.
 A part of sulphur from the residues of plant
and animal losses to atmosphere.
 The sulphur from atmosphere comes down
with acid rain.

17. Fig:- The Sulphur Cycle

18. REDUCTION-OXIDATION REACTION OF SULPHUR
 Sulphur exits in more than one oxidation
states, hence it is subjected to the reduction-
oxidation reaction in soil.
 In the reduction-oxidation processes, SO4 is
the last ion to undergo reduction after all the
ions have been reduced, thus intense
reduction conditions are necessary.
 During decomposition of organic matter
under normal arable soil conditions, organic
sulphur compounds are oxidized to sulphates.

19. OPTIMUM N:S RATIO
 Sulphur metabolism in plants is closely linked
with N, as both are constituents of proteins.
 The desired N:S ratio for optimum growth and
metabolism in plants has been found to be 15-
16:1 in legumes and 11-12:1 in cereals.
 The optimum fertilizer N:S ratio varies among
soils because of differences in the available
soil N and S levels.

20. INTERACTION OF ‘S’ NUTRIENT WITH OTHER NUTRIENTS
 S and Fe:- Low level of S exhibited low iron uptake.
 S and Mn:- Application of S fertilizer to soil will
enhance Mn uptake by the plants.
 S and Cu:- Application of S increased the conc. of Cu in
the leaves due to the better uptake.
 S and Zn:- Antagonistic relationship between S and Zn
is observed.
 S and B:- Positive interaction between B and S.
 S and Mo:- Antagonistic relationship between S and Mo
is observed.
 S and Cl:- Mutual antagonistic relationship.

21. IMPORTANCE OF SULPHUR NUTRITION IN
INDIAN AGRICULTURE
 In India, S-deficiencies are found in almost
40% of the cultivated area
 Different crop species have different S
requirements.
 S-bearing compounds like non volatile S-
glucocides. Sulphur in brassica seeds is
around 1.19%, in straw it is 0.19%and in
legumes it is 0.25%.