FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIF1CA TION
(See section 10, rule 13)
1. Title of the invention
A NUTRITIONAL COMPOSTION FOR PLANTS AND A METHOD OF PREPARATION THEREOF
2. Applicant(s)
Name Nationality Address
TATA CHEMICALS LIMITED INDIA BOMBAY HOUSE, 24 HOMI MODI STREET, MUMBAI -
400001, INDIA
3. Preamble to the description
COMPLETE SPEC1F1CA TION
The following specification particularly describes the invention and the manner in which it is
to be performed.

The present disclosure provides a nutritional composition for plants and a method of preparing a nutritional composition for plants.
BACKGROUND
In agriculture, it is known that the optimum development of plants is dependent upon the dosage of essential nutrients provided to them. Absence of even a single essential nutrient can lead to poor growth, deficiency symptoms and a drastic reduction in crop yield. Even though all of the other essential nutrients may be present in optimum quantities, the one nutrient which is present in a sub-optimum quantity may thus become the limiting factor, thereby seriously retarding the development of plants.
Essential nutrients for plants include macronutrients and micronutrients. Macronutrients are consumed in larger quantities and are present in plant tissue in quantities from 0.2% to 4.0% (on a dry matter weight basis). Macronutrients include nitrogen, potassium, phosphorus, silicon etc. Micronutrients are present in plant tissue in quantities measured in parts per million, ranging from 5 to 200 ppm, or less than 0.02% dry weight. Micronutrients include metal ions, such as Cu, Zn, Mn, Fe etc.
Conventionally available nutritional compositions used for delivering micronutrients to crops, include metal sulphates and EDTA based compositions. Such metal sulphates are cheap but tend to react with other soil components and form insoluble compounds which render micronutrients unavailable to the growing crops. On the other hand, EDTA based compositions are expensive and not significantly efficient in terms of increasing overall yield of crops. Further, such nutritional compositions are required in large quantities to deliver optimum amount of micronutrients to the plants, which is unaffordable for the agriculturalists.

There is therefore a need of a nutritional composition for plants which is efficient and cost effective and delivers nutrients in a form which is readily available to the plants. There is also a need for a method of preparing such a nutritional composition.
SUMMARY
A nutritional composition for plants is disclosed. The nutritional composition comprises of silica nanoparticles having at least one micronutrient adsorbed thereon, wherein the micronutrient comprises at least 1% (w/w) of the nutritional composition, the nutritional composition having particle size not more than 1000 nm.
A method of preparing a nutritional composition for plants is also disclosed. The method comprises of preparing a precursor solution of at least one micronutrient, adding silica nanoparticles to the precursor solution to obtain silica nanoparticles having at least one micronutrient adsorbed thereon and separating the silica nanoparticles having at least one micronutrient adsorbed thereon from the solution obtained in the previous step, such silica nanoparticles being suitable for use as a nutritional composition for plants wherein the micronutrient comprises at least 1% (w/w) of the nutritional composition, the nutritional composition having particle size not more than 1000 nm.
An alternate method of preparing a nutritional composition for plants is also disclosed. The method comprises of preparing a precursor solution of at least one micronutrient in acid or water, adding sodium silicate to the precursor solution to obtain silica nanoparticles having at least one micronutrient adsorbed thereon and separating the silica nanoparticles having at least one micronutrient adsorbed thereon from the solution obtained in the previous step , such silica nanoparticles being suitable for use as a nutritional composition for plants wherein the micronutrient comprises at least 1% (w/w)

of the nutritional composition, the nutritional composition having particle size not more than 1000 nm.
DETAILED DESCRIPTION
For the purpose of promoting an understanding of the principles of the invention, reference will now be made to embodiments and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the disclosed process, and such further applications of the principles of the invention therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof.
Reference throughout this specification to "one embodiment" "an embodiment" or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrase "in one embodiment", "in an embodiment" and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.
The present disclosure provides a nutritional composition for plants and a method of preparing the same. Particularly, the present disclosure provides a nutritional composition for delivery of nutrients to plants. The nutritional composition comprises of silica nanoparticles having at least one micronutrient adsorbed thereon, wherein the micronutrient comprises at least 1 % (w/w) of the nutritional composition, the nutritional composition having particle size not more than 1000 nm.

In accordance with an embodiment, the nutritional composition comprises of micronutrient in a range of 1 % - 20% (w/w).
In accordance with an aspect, the micronutrient is iron, zinc, copper, manganese, boron, molybdenum or combination thereof.
In accordance with an aspect, the micronutrient is chelated if the micronutrient is iron, manganese or copper.
In accordance with an aspect, silica nanoparticles have a particle size in a range of lO nmto 1000 nm.
The present disclosure also provides a method of preparing a nutritional composition for plants. The method comprises of preparing a precursor solution of at least one micronutrient; adding silica nanoparticles to the precursor solution to obtain silica nanoparticles having at least one micronutrient adsorbed thereon and separating the silica nanoparticles having at least one micronutrient adsorbed thereon from the solution obtained in the previous step , such silica nanoparticles being suitable for use as a nutritional composition for plants wherein the micronutrient comprises at least 1% (w/w) of the nutritional composition, the nutritional composition having particle size not more than 1000 nm.
In accordance with an aspect, the micronutrient is iron, zinc, copper, manganese, boron, molybdenum or combination thereof.
In accordance with an embodiment, the precursor solution is prepared by dissolving a salt of micronutrient in water. The salt of micronutrient is selected from sulphate, chloride and nitrate.
In accordance with a preferred embodiment, the precursor solution is prepared by dissolving hydrated sulphate salt of micronutrient in water. By way of example, 2.7 grams

of zinc sulphate monohydrate is dissolved in 100 ml of water to obtain a precursor solution of zinc.
In accordance with an embodiment, the method further comprises of adding a chelating agent to the precursor solution to facilitate chelation of micronutrient. In accordance with a preferred embodiment, chelating agent is added to the precursor solution of iron, manganese or copper. Chelation of micronutrient(s) renders micronutrient(s) available to the plants by preventing oxidation and reaction of micronutrient(s) with other soil components.
In accordance with an embodiment, the chelating agent is selected from ascorbic acid, acetic acid, citric acid, iactic acid, orthophosphoric acid and glucose.
In accordance with an embodiment, silica nanoparticles are synthesized ex-situ. The ex-situ synthesized silica nanoparticles are selected from un-modified silica nanoparticles, gelatin modified silica nanoparticles, octylamine functionalized silica nanoparticles and mesoporous silica nanoparticles. Silica nanoparticles are highly porous and have high surface area which facilitate high adsorption of micronutrients thereon. Silica nanoparticles synergistically act as a carrier for delivery of micronutrients to the plants and also provide nutrient to plants in the form of silicon.
In accordance with an embodiment, the silica nanoparticles used in the method disclosed herein, are obtained by the process disclosed in the co-pending Indian Patent Application No. 1510/MUM/2010, which is incorporated herein by reference.
In accordance with an aspect, silica nanoparticles have a particle size in a range of l0 nmto 1000 nm.
In accordance with an embodiment, the solution obtained after adding silica nanoparticles to the precursor solution is stirred for a time period in a range of 12-18 hours to facilitate adsorption of micronutrient on silica nanoparticles.

In accordance with an embodiment, separation of the silica nanoparticles having at least one micronutrient adsorbed thereon from the solution is carried out by centrifugation or filtration.
In accordance with an embodiment, centrifugation is carried out at a speed in a range of 4000-8000 rpm for 5 minutes.
In accordance with an alternate embodiment, centrifugation is carried out twice at a speed in a range of 4000-8000 rpm for 5 minutes.
In accordance with an embodiment, subsequent to the separation, the silica nanoparticles having at least one micronutrient adsorbed thereon are dried and ground. By way of example, subsequent to the centrifugation, supernatant is discarded and thus obtained precipitate is dried and ground.
In accordance with an embodiment, drying is carried out at a temperature of 60 °C to obtain dried silica nanoparticles with micronutrient adsorbed thereon suitable for use as a nutritional composition for plants. Inductively Coupled Plasma (ICP) analysis of the dried silica nanoparticles with micronutrient adsorbed thereon shows 1-20% (w/w) loading of micronutrients on silica nanoparticles.
In accordance with an alternate embodiment, subsequent to the separation, the silica nanoparticles having at least one micronutrient adsorbed thereon are ground and dispersed in water to obtain slurry suitable for use as a nutritional composition for plants.
The present disclosure also provides an alternate method of preparing a nutritional composition for plants. The method comprises of preparing a precursor solution of at least one micronutrient in acid or water, adding sodium silicate to the precursor solution to obtain silica nanoparticles having at least one micronutrient adsorbed thereon and separating the silica nanoparticles having at least one micronutrient adsorbed thereon from the solution obtained in the previous step, such silica nanoparticles being suitable for use

as a nutritional composition tor plants wherein the micronutrient comprises at least 1% (w/w) of the nutritional composition, the nutritional composition having particle size not more than 1000 nm.
In accordance with an aspect, the micronutrient is iron, zinc, copper, manganese, boron, molybdenum or combination thereof.
.In accordance with an embodiment, the precursor solution is prepared by dissolving a salt of micronutrient in water. The salt of micronutrient is selected from sulphate, chloride and nitrate.
In accordance with a preferred embodiment, the precursor solution is prepared by dissolving hydrated sulphate salt of micronutrient in water. By way of example, 20 grams of FeSO4. 7H2O is dissolved in 100 ml of water to obtain precursor solution of iron followed by addition of sodium silicate to obtain iron adsorbed on silica nanoparticles. In general, the reaction mechanism involved in the method, when hydrated sulphate salt is dissolved in water to prepare precursor solution, is as follows:
M-SO4 + H20 → M++ + S04 - - + H+ +OH→ M++ + HSO- 4 + OH-
M++ + HSO- 4 + OH - + Na2SiO3 + NaOH → M@SiO2 + Na2SO4 + H2O
wherein M represents micronutrient; and
M@SiO2 represents micronutrient adsorbed on silica nanoparticles.
In accordance with an alternate embodiment, the precursor solution is prepared by dissolving a salt of micronutrient in an acid. The salt of micronutrient is selected from sulphate, chloride, oxide and nitrate.
In accordance with a preferred embodiment, the precursor solution is prepared by dissolving hydrated sulphate salt of micronutrient in acid. By way of example, 12.2 grams of zinc sulphate monohydrate is dissolved in 50 ml of 5M sulphuric acid to obtain

precursor solution of zinc. To this, a solution of sodium silicate is added to obtain zinc adsorbed on silica nanoparticles. In general, the reaction mechanism involved in the method, hydrated sulphate salt is dissolved in acid to prepare precursor solution, is as follows:
M-SO4 + H2O + H2SO4 → M++ + SO4- + H2O + H2SO4
M++ + SO4-- + H2O + H2SO4 + Na2SiO3 +NaOH→ M@SiO2 + Na2SO4 + H2O.
wherein M represents micronutrient; and
M@SiO2 represents micronutrient adsorbed on silica nanoparticles.
In accordance with an alternate embodiment, the precursor solution is prepared by dissolving oxides of micronutrient in acid. By way of example, 33.1 grams of zinc oxide is dissolved in 280 .ml of 1.25 M sulphuric acid to obtain a precursor solution of zinc.
In accordance with an embodiment, the method further comprise of adding a chelating agent to the precursor solution to facilitate chelation of micronutrient. In accordance with a preferred embodiment, chelating agent is added to the precursor solution of iron, manganese or copper. Chelation of micronutrient(s) renders micromitrient(s) available to the plants by preventing oxidation and reaction of micronutrient(s) with other soil components.
In accordance with an embodiment, the chelating agent is selected from ascorbic acid, acetic acid, citric acid, lactic acid, orthophosphoric acid and glucose. In general, the reaction mechanism involved in the method, when the chelating agent is used, is as follows:
M-SO4 + H2O + Chelating Agent → M-Chelated complex + H++OH- + S04- +
Na2SiO3 + NaOH
M-Chelated @SiO2 + Na2SO4

wherein M represents micronutrient; and
M-chelated@Si02 represents chelated micronutrient adsorbed on silica nanoparticles. By
way of example, the reaction mechanism involved in the method, when the chelating agent
is orthophosphoric acid, is as follows:
M-SO4 + H2O + H3PO4 → M-PO4 + H+ + H2SO4 + Na2SiO3 + NaOH
M-PO4 @SiO2+ Na2SO4 + H2O wherein M represents micronutrient; and
M-P04@SiO2 represents chelated micronutrient adsorbed on silica nanoparticles
In accordance with an embodiment, the method further comprises of adding
capping agent to the precursor solution. Addition of capping agent facilitates formation of
surface modified silica nanoparticles. Surface modified silica nanoparticles are highly
porous and have high surface area which facilitates high adsorption of micronutrients
thereon. The capping agent is added to the precursor solution in a range of 0.5 to 8 weight
percent.
In accordance with an embodiment, the capping agent is selected from gelatin,
octylamine, chitosan and other surfactants.
In accordance with a preferred embodiment, addition of gelatin is followed by
heating of precursor solution to facilitate complete dissolution of gelatin. By way of
example, 12.2 grams of zinc sulphate monohydrate is dissolved in 50 ml of 5M sulphuric
acid to obtain precursor solution of zinc. 2% gelatin is added to the precursor solution
followed by heating at a temperature of 90°C till gelatin is completely dissolved.
In accordance with a preferred embodiment, chelating agent is added prior to the
addition of capping agent to the precursor solution. By way of example, 4.02 ml of 88%
orthophoshoric acid (OPA) is added to 100 ml of water followed by addition of 55.6 grams

of FeS04. 7H20. 2 grams of gelatin is added to the solution obtained in previous step, followed by heating at a temperature of 90 °C to facilitate complete dissolution of gelatin.
In accordance with an embodiment, sodium silicate is added to the precursor solution to obtain silica nanoparticles having at least one micronutrient adsorbed thereon. The sodium silicate used can either be synthesized by boiling rice husk ash in an aqueous solution of sodium hydroxide or commercially available sodium silicate solution. The sodium silicate solution has a concentration in a range of 1-45 weight percent. By way of an example, rice husk ash is boiled in an aqueous solution of sodium hydroxide to obtain a solution of sodium silicate such that the concentration of sodium silicate in said solution is 14% (w/v). Sodium silicate solution is added drop wise till the pH of the precursor solution is in a range of 6-7. Addition of sodium silicate facilitates in-situ synthesis of silica nanoparticles.
In accordance with a preferred embodiment, subsequent to the dissolution of gelatin, the precursor solution is cooled to room temperature followed by addition of sodium silicate to obtain silica nanoparticles having at least one micronutrient adsorbed thereon.
In accordance with an embodiment, separation of the silica nanoparticles having at least one micronutrient adsorbed thereon from the solution is carried out by centrifugation or filtration.
In accordance with an embodiment, centrifugation is carried out at a speed in a range of 4000-8000 rpm for 5 minutes.
In accordance with an alternate embodiment, centrifugation is carried out twice at a speed in a range of 4000-8000 rpm for 5 minutes.
In accordance with an embodiment, subsequent to the separation, the silica nanoparticles having at least one micronutrient adsorbed thereon are dried and ground. By

way of example, subsequent to the centrifugation, supernatant is discarded and thus obtained precipitate is dried and ground.
In accordance with an embodiment, drying is carried out at a temperature of 60 °C to obtain dried silica nanoparticles with micronutrient adsorbed thereon suitable for use as a nutritional composition for plants. Inductively Coupled Plasma (ICP) analysis of the dried silica nanoparticles with micronutrient adsorbed thereon shows 1 -20% (w/w) loading of micronutrients on silica nanoparticles.
In accordance with an alternate embodiment, subsequent to the separation, the silica nanoparticles having at least one micronutrient adsorbed thereon are ground and dispersed in water media to obtain slurry suitable for use as a nutritional composition for plants.
The following example(s) of method for preparing a nutritional composition for plants are exemplary and should not be understood to be in any way limiting.
Example 1:
Zinc loading on ex-situ synthesized silica nanoparticles
In 100 ml water, 2.7 grams of zinc sulfate monohydrate is dissolved. 1 gram of octylamine functionalized silica is added to the solution obtained, followed by stirring for 16 hours. The solution is centrifuged twice at 8000 rpm for 5 minutes. After discarding the supernatant, the pellet was dried to obtain silica nanoparticles with zinc adsorbed thereon. ICP analysis shows Zn loading of 2%.
Example 2:
Zinc loading on ex-situ synthesized silica nanoparticles
In 100 ml water, 2.7 grams of zinc sulfate monohydrate is dissolved. 1 gram of gelatin modified silica is added to the solution obtained, followed by stirring for 16 hours.

The solution is centrifuged twice at 8000 rpm for 5 minutes. After discarding the supernatant, the pellet was dried to obtain silica nanoparticles with zinc adsorbed thereon. 1CP analysis shows Zn loading of 4%.
Example 3:
Zinc loading on in-situ synthesized silica nanoparticles
In 50 ml of 5M H2SO4 solution, 12.2 grams of zinc sulfate monohydrate is added. 235 mL of 7% RHA extracted sodium silicate is added to the solution obtained, thereby facilitating neutralization of the solution. Thus obtained solution is centrifuged. After discarding the supernatant, the pellet was dried to obtain silica nanoparticles with zinc adsorbed thereon. ICP analysis shows Zn loading of 9%.
Example 4:
Zinc loading on in-situ synthesized silica nanoparticles
In 50 ml of 5M H2SO4 solution, 12.2 grams of zinc sulfate monohydrate is added. 2% gelatin is added to the solution the solution obtained in previous step. 235 mL of 7% RHA extracted sodium silicate is added to the solution obtained in previous step, thereby facilitating neutralization of the solution. Thus obtained solution is centrifuged. After discarding the supernatant, the pellet was dried to obtain silica nanoparticles with zinc adsorbed thereon. ICP analysis shows Zn loading of 9%.
Example 5:
Zinc loading on in-situ synthesized silica nanoparticles
In 350 ml of 1.25M H2SO4 solution, 33.1 grams of zinc oxide is added and stirred until complete dissolution. 1-2% gelatin is added to the solution obtained in previous step. 400 mL of 14% sodium silicate (obtained from RHA or commercial grade) is added to the solution obtained in previous step, thereby facilitating neutralization of the solution. Thus

obtained solution is centrifuged. After discarding the supernatant, the pellet was dried to obtain silica nanoparticles with zinc adsorbed thereon. ICP analysis shows Zn loading of 16-20%, depending on the grade of zinc oxide (commercial grade or lab grade) used.
Example 6:
Zinc loading on in-situ synthesized silica nanoparticles
In 711 ml of 1.25 M H2SO4, 875 grams of zinc sulfate heptahydrate is dissolved. To this 14.2 grams of gelatin is added and thus obtained solution is heated to completely dissolve gelatin. The solution is neutralized by addition of RHA extracted sodium silicate. Thus obtained solution is centrifuged. After discarding the supernatant, the pellet is dried to obtain silica nanoparticles with zinc adsorbed thereon. ICP analysis shows Zn loading of 14-18%. Alternatively, in place of RHA extracted sodium silicate, 14% (w/v) sodium silicate solution (commercially available) can be used.
Example 7:
Zinc loading on in-situ synthesized silica nanoparticles
In 50 ml of water, 61.5 grams zinc sulfate heptahydrate is dissolved. To this 1 gram of gelatin is added and thus obtained solution is heated to completely dissolve gelatin. The solution is neutralized by addition of 200 mL of 14% commercial grade sodium silicate. Thus obtained solution is centrifuged. After discarding the supernatant, the pellet is dried to obtain silica nanoparticles with zinc adsorbed thereon. ICP analysis shows Zn loading of 20.65%.
Example 8:
Iron loading on ex-situ synthesized silica nanoparticles
In 100 ml of distilled water, 10 grams of silica along with 20 grams of FeSO,*. 7H2O is added and kept overnight (18 hours) under stirring conditions. Thus obtained

solution is centrifiiged at 4000 RPM for 5 minutes at room temperature. After discarding the supernatant, the pellet is dried at 60 °C to obtain silica nanoparticles with iron adsorbed thereon. ICP analysis shows Fe loading of 8.8%.
Example 9:
Iron loading on in-situ synthesized silica nanoparticles
In 30.5 mL of 1.25M H2S04, 20 grams of FeSO4. 7H20 is added under stirring. After 10 minutes 0.61 grams of gelatin is added and the solution is heated at 90 degrees till the gelatin is completely dissolved. The solution is then cooled to room temperature followed by addition of 14% sodium silicate solution drop wise till the entire solution neutralizes (pH ~ 6-7). A dark green/black gel is obtained, which was washed with hot water to remove excess gelatin and then centrifiiged at 4000 rpm for 5 minutes. The pellet was dried at 60 °C after discarding the supernatant to obtain silica nanoparticles with iron adsorbed thereon. ICP analysis shows Fe loading of 8.0%.
Example 10:
Iron loading on in-situ synthesized silica nanoparticles
In 100 ml of water 20 grams of FeSO4.7H2O is added. Ascorbic acid (1:0.5 of Fe: Ascorbic acid) is also dissolved in the solution obtained in the previous step. After dissolution, concentrated H2SO4 is added so as to make the final concentration of H2SO4 in the solution to 1.25 M. To this 2.6 grams of gelatin is added and the solution is heated at 90 degrees till the gelatin is completely dissolved. The solution is then cooled to room temperature followed by addition of 14% sodium silicate solution drop wise till the entire solution neutralizes (pH ~ 6-7). A dark green/black gel is obtained, which was washed with hot water to remove excess gelatin and then centrifiiged at 4000 rpm for 5 minutes.

The pellet was dried at 60°C after discarding the supernatant to obtain silica nanoparticles with iron adsorbed thereon. ICP analysis shows Fe loading of 1.11 %.
Example 11:
Iron loading on in-situ synthesized silica nanoparticles
In 100 ml of water 20 grams of FeSO4.7H2O is added. Gelatin is added to the solution obtained in the previous step followed by heating of the solution to completely dissolve gelatin and the solution is cooled to room temperature. Ascorbic acid (1:0.5 of Fe: Ascorbic acid) is then dissolved in the solution obtained from previous step. After dissolution, concentrated H2SO4 is added so as to make the final concentration of H2SO4 in the solution to 1.25 M. To this 2.6 grams of gelatin is added and the solution is heated at 90 degrees till the gelatin is completely dissolved. The solution is then cooled to room temperature followed by addition of 14% sodium silicate solution drop wise till the entire solution neutralizes (pH ~ 6-7). A dark green/black gel is obtained, which was washed with hot water to remove excess gelatin and then centrifuged at 4000 rpm for 5 minutes. The pellet was dried at 60 °C after discarding the supernatant to obtain silica nanoparticles with iron adsorbed thereon. ICP analysis shows Fe loading of 3.3-4.7%.
Alternatively, in place of ascorbic acid, other chelating agents, such as acetic acid, citric acid, lactic acid or glucose, with varying ratio with iron are also used and the ICP analysis of Fe loading varies between 3-5%.
Example 12:
Iron loading on in-situ synthesized silica nanoparticles
Method is same as that disclosed in example 8 without the addition of H2SO4 and ICP_analysis of thus obtained silica nanoparticles with iron adsorbed thereon shows Fe loading of 11.5%.

Example 13:
Iron loading on in-situ synthesized silica nanoparticles
In 100 ml water, 4.02 ml of 88% orthophosphoric acid (OPA) is added. To this solution, 20 grams of FeSO4 7H2O is added (OPA:Fe = 1:1) followed by addition of 2 grams of gelatin . Thus obtained solution is heated till the gelatin dissolves completely followed by cooling of the solution to room temperature. 14% sodium silicate solution is added drop wise till neutralization. Thus obtained solution is centrifuged. The pellet was dried at 60 °C after discarding the supernatant to obtain silica nanoparticles with iron adsorbed thereon. ICP analysis shows Fe loading of 13.12%.
Example 14:
Iron loading on in-situ synthesized silica nanoparticles
In 100 ml water, 11.52 ml of 88% orthophosphoric acid (OPA) is added. To this solution, 55.6 grams of FeSO4 7H2O is added (OPA:Fe =1:1) followed by addition of 2 grams of gelatin . Thus obtained solution is heated till the gelatin dissolves completely followed by cooling of the solution to room temperature. 14% sodium silicate solution is added drop wise till neutralization. Thus obtained solution is centrifuged. The pellet was dried at 60 °C after discarding the supernatant to obtain dried silica nanoparticles with iron adsorbed thereon. ICP analysis shows Fe loading of 15.3%.
Example 15:
Manganese loading on ex-situ synthesized silica nanoparticles In 100 mL of distilled water, 10 grams of silica along with 30 grams of MnSO4. H2O is added and kept overnight (18 hours) under stirring conditions. The solution thus obtained is centrifuged at 4000 RPM for 5 minutes at room temperature. The pellet was

dried at 60 °C after discarding the supernatant to obtain dried silica nanoparticles with manganese adsorbed thereon. ICP analysis shows Mn loading of 11.5%.
Example 16:
Manganese loading on in-situ synthesized silica nanoparticles In 100 ml distilled water, 30 grams of MnS04.H20 is dissolved. After dissolution, 20.34 ml of acetic acid is added followed by addition of concentrated H2SO4 such that the final H2SO4 concentration in solution reaches 1.25 M. To this, 2.7 grams of gelatin is added and the solution is heated till gelatin dissolves followed by cooling to room temperature. 14% sodium silicate was solution is added drop wise till the solution neutralizes. The solution thus obtained is centrifuged at 4000 RPM for 5 minutes at room temperature. The pellet was dried at 60 °C after discarding the supernatant to obtain dried silica nanoparticles with manganese adsorbed thereon. ICP analysis shows Mn loading of 5.34%.
Example 17:
Manganese loading on in-situ synthesized silica nanoparticles In 100 mL distilled water, 30 grams of MnS04.H20 is dissolved. After dissolution, 20.34 ml of acetic acid is added. To this, 2.7 grams of gelatin is added and the solution is heated till gelatin dissolves followed by cooling to room temperature. 14% sodium silicate was solution is added drop wise till the solution neutralizes. The solution thus obtained is centrifuged at 4000 RPM for 5 minutes at room temperature. The pellet was dried at 60 °C after discarding the supernatant to obtain dried silica nanoparticles with manganese adsorbed thereon. ICP analysis shows Mn loading of 10%.

Example 18:
Copper loading on ex-situ synthesized silica nanoparticles
In 100 mL of distilled water, 10 grams of silica along with 24 grams of CUSO4. 5H2O is added and kept overnight (18 hours) under stirring conditions. The solution was centrifuged at 4000 RPM for 5 minutes at room temperature. The pellet was dried at 60 degrees C after discarding the supernatant to obtain dried silica nanoparticles with copper adsorbed thereon. ICP analysis shows Cu loading of 10.24%.
In another experiment, a chelating agent (citric acid) is added to the solution of CuSO4. 5H2O prior to the addition of silica. The solution thus obtained was centrifuged at 4000 RPM for 5 minutes at room temperature. The pellet was dried at 60 degrees C after discarding the supernatant to obtain dried silica nanoparticles with copper adsorbed thereon. ICP analysis shows Cu loading of 10.3%.
Example 19:
Copper loading on in-situ synthesized silica nanoparticles
In 100 ml distilled water, 24 grams of CuS04.5H20 is dissolved. After dissolution, 20.18 grams of citric acid is added followed by addition of concentrated H2SO4 such that the final H2SO4 concentration in thus obtained solution reaches 1.25 M. To this, 2.6 grams of gelatin is added and the solution is heated till gelatin dissolves followed by cooling to room temperature. After cooling, 14% sodium silicate solution is added drop wise till the solution neutralizes. The solution thus obtained was centrifuged and washed twice at 4000 RPM for 5 minutes at room temperature. The pellet was dried at 60 degrees C after discarding the supernatant to obtain dried silica nanoparticles with copper adsorbed thereon. ICP analysis shows Cu loading of 2-3%.

Example 20:
Copper loading on in-situ synthesized silica nanoparticles
In 100 ml distilled water, 24 grams of CuSO4. 5H2O is dissolved. After dissolution, 20.18 grams of citric acid is added. To this, 2.6 grams of gelatin is added and the solution is heated till gelatin dissolves followed by cooling to room temperature. After cooling, 14% sodium silicate solution is added drop wise till the solution neutralizes. The solution thus obtained was centrifuged at 4000 RPM for 5 minutes at room temperature. The pellet was dried at 60 degrees C after discarding the supernatant to obtain dried silica nanoparticles with copper adsorbed thereon. ICP analysis shows Cu loading of 11.5%.
Example 21:
Zinc and Boron loading on in-situ synthesized silica nanoparticles In 122 ml of 1.25 M sulfuric acid solution, 150 grams of zinc sulfate heptahydrate is added. After complete dissolution 33.36 grams of boric acid is added to the solution obtained in the previous step followed heating at 90 degrees C to facilitate complete dissolution of boric acid. After dissolution of boric acid, 2.44 grams of gelatin is added to the solution obtained in previous step. To facilitate complete dissolution of gelatin, heating is continued for 30 minutes. To this solution, 14% sodium silicate solution is added till neutralization (pH -6-7). The solution thus obtained was centrifuged and washed twice at 4000 RPM for 5 minutes at room temperature. The pellet was dried after discarding the supernatant to obtain dried silica nanoparticles with zinc and boron adsorbed thereon. ICP analysis shows Zn loading of 12-13% and B loading of 0.6-2%.
Example 22:
Molybdenum loading on in-situ synthesized silica nanoparticles

In 80 ml of 1.25 M sulfuric acid, 3 grams of ammonium molybdate is added and stirred until complete dissolution. To this solution, 1.6 grams of gelatin is added and the solution was heated till the gelatin is completely dissolved. To this solution, 14% sodium silicate is added drop wise till neutralization. The solution thus obtained was centrifuged at 4000 RPM for 5 minutes at room temperature. The pellet was dried after discarding the supernatant to obtain dried silica nanoparticles with zinc and boron adsorbed thereon. ICP analysis shows Mo loading of 4.26%.
SPECIFIC EMBODIMENTS ARE DESCRIBED BELOW
A nutritional composition for plants comprising silica nanoparticles having at least one micronutrient adsorbed thereon, wherein the micronutrient comprises at least 1% (w/w) of the nutritional composition, the nutritional composition having particle size not more than 1000 nm.
Such nutritional composition(s), wherein the micronutrient is iron, zinc, copper, manganese, boron, molybdenum or combination thereof.
Such nutritional composition(s), wherein the micronutrient is chelated if the micronutrient is iron, manganese or copper.
Such nutritional composition(s), wherein silica nanoparticles have a particle size in a range of 10 nm to 1000 nm.
FURTHER SPECIFIC EMBODIMENTS ARE DESCRIBED BELOW
A method of preparing a nutritional composition for plants comprising preparing a precursor solution of at least one micronutrient; adding silica nanoparticles to the precursor solution to obtain silica nanoparticles having at least one micronutrient adsorbed thereon; and separating the silica nanoparticles having at least one micronutrient adsorbed thereon from the solution obtained in the previous step, such silica nanoparticles being suitable for

use as a nutritional composition for plants wherein the micronutrient comprises at least 1% (w/w) of the nutritional composition, the nutritional composition having particle size not more than l000nm.
Suchmethod(s), further comprising adding a chelating agent to the precursor solution.
Such method(s), wherein chelating agent is selected from ascorbic acid, acetic acid, citric acid, lactic acid, orthophosphoric acid and glucose.
Such method(s), wherein silica nanoparticles have a particle size in a range of 10 nm to 1000 nm.
Such method(s), wherein the micronutrient is iron, manganese, zinc, copper, boron, molybdenum or combination thereof.
Such method(s), wherein silica nanoparticles are selected from un-modified silica nanoparticles, gelatin modified silica nanoparticles, octylamine functionalized silica nanoparticles and mesoporous silica nanoparticles.
FURTHER SPECIFIC EMBODIMENTS ARE DESCRIBED BELOW
A method of preparing a nutritional composition for plants comprising preparing a precursor solution of at least one micronutrient in acid or water; adding sodium silicate to the precursor solution to obtain silica nanoparticles having at least one micronutrient adsorbed thereon; and separating the silica nanoparticles having at least one micronutrient adsorbed thereon from the solution obtained in the previous step , such silica nanoparticles being suitable for use as a nutritional composition for plants wherein the micronutrient comprises at least 1% (w/w) of the nutritional composition, the nutritional composition having particle size not more than 1000 nm.

Such method(s), wherein the micronutrient is iron, manganese, zinc, copper, boron, molybdenum or combination thereof.
Such method(s), further comprising adding a capping agent to the precursor solution.
Such method(s), wherein capping agent is selected from gelatin, octylamine, chitosan and other surfactants.
Such method(s), further comprising adding a chelating agent to the precursor solution.
Such method(s), wherein chelating agent is selected from ascorbic acid, acetic acid, citric acid, lactic acid, orthophosphoric acid and glucose.
INDUSTRIAL APPLICATION
The nutritional composition disclosed above is cost effective and highly efficient in delivering silicon and micronutrient(s) to plants. Further, the nutritional composition is capable of delivering nutrients in a form which is readily available to the plants. The method of preparing a nutritional composition for plants as disclosed above is easy to perform and economical. Further, the method allows high loading of micronutrient(s) on silica nanoparticles. Therefore, less amount of the nutritional composition is required to deliver optimum amount of micronutrient(s) to the plants, thereby making it cost effective for the farmers. Furthermore, silica nanoparticles synergistically act as a carrier for delivery of micronutrients to the plants and also provide nutrient to plants in the form of silicon.

WE CLAIM:
1. A nutritional composition for plants comprising silica nanoparticles having at least one micronutrient adsorbed thereon, wherein the micronutrient comprises at least 1% (w/w) of the nutritional composition, the nutritional composition having particle size not more than 1000 nm.
2. A nutritional composition for plants as claimed in claim 1, wherein the micronutrient is iron, zinc, copper, manganese, boron, molybdenum or combination thereof.
3. A nutritional composition for plants as claimed in claim 2, wherein the micronutrient is chelated if the micronutrient is iron, manganese or copper.
4. A nutritional composition for plants as claimed in claim 1, wherein silica nanoparticles have a particle size in a range of 10 nm to 1000 nm.
5. A method of preparing a nutritional composition for plants comprising:
preparing a precursor solution of at least one micronutrient;
adding silica nanoparticles to the precursor solution to obtain silica nanoparticles having at least one micronutrient adsorbed thereon; and
separating the silica nanoparticles having at least one micronutrient adsorbed thereon from the solution obtained in the previous step, such silica nanoparticles being suitable for use as a nutritional composition for plants wherein the micronutrient comprises at least 1% (w/w) of the nutritional composition, the nutritional composition having particle size not more than 1000 nm.

6. A method of preparing a nutritional composition for plants as claimed in claim 5, further comprising adding a chelating agent to the precursor solution.
7. A method of preparing a nutritional composition for plants as claimed in claim 6, wherein chelating agent is selected from ascorbic acid, acetic acid, citric acid, lactic acid, orthophosphoric acid and glucose.
8. A method of preparing a nutritional composition for plants as claimed in claim 5, wherein silica nanoparticles have a particle size in a range of 10 nm to 1000 nm.
9. A method of preparing a nutritional composition for plants as claimed in claim 5, wherein the micronutrient is iron, manganese, zinc, copper, boron, molybdenum or combination thereof.
10. A method of preparing a nutritional composition for plants as claimed in claim 5, wherein silica nanoparticles are selected from un-modified silica nanoparticles, gelatin modified silica nanoparticles, octylamine functionalized silica nanoparticles and mesoporous silica nanoparticles.
11. A method of preparing a nutritional composition for plants comprising:
preparing a precursor solution of at least one micronutrient in acid or water;
adding sodium silicate to the precursor solution to obtain silica nanoparticles having at least one micronutrient adsorbed thereon; and
separating the silica nanoparticles having at least one micronutrient adsorbed thereon from the solution obtained in the previous step , such silica nanoparticles being suitable for use as a nutritional composition for plants wherein the

micronutrient comprises at least 1% (w/w) of the nutritional composition, the nutritional composition having particle size not more than 1000 nm.
12. A method of preparing a nutritional composition for plants as claimed in claim 11, wherein the micronutrient is iron, manganese, zinc, copper, boron, molybdenum or combination thereof.
13. A method of preparing a nutritional composition for plants as claimed in claim 11, further comprising adding a capping agent to the precursor solution.
14. A method of preparing a nutritional composition for plants as claimed in claim 13, wherein capping agent is selected from gelatin, octylamine, chitosan and other surfactants.
15. A method of preparing a nutritional composition for plants as claimed in claim 11, further comprising adding a chelating agent to the precursor solution.
16. A method of preparing a nutritional composition for plants as claimed in claim 15, wherein chelating agent is selected from ascorbic acid, acetic acid, citric acid, lactic acid, orthophosphoric acid and glucose.