TECHNICAL FIELD
The present disclosure relates to sustained release fertilizers. More particularly, the present invention relates to a sustained release fertilizer comprising organic carbon cross-linked with calcium, nitrogen and phosphate/phosphorous. BACKGROUND OF THE DISCLOSURE
Nitrogen, phosphorus and calcium are important macronutrients. But these are not adequately available in natural soils to support the sustained growth of plants. As a result, these macronutrients are needed to be applied externally through fertilizers. Water soluble conventional fertilizers typically result in a large amount of macronutrients being lost by leaching and evaporation. There is an increased interest in developing sustained release fertilizers that release macronutrients to plants over time. Advantages of sustained release fertilizers are improved efficiency and quality as the fertilizer is released over time thus providing sufficient quantities of macronutrients as required for higher crop yields. In addition, sustained release fertilizers result in reduced environmental damage from leaching of macronutrients into water and emissions as gasses, compared to conventional water-soluble fertilizers.
Of the three macronutrients, nitrogen is a key macronutrient source in agriculture particularly for economic crops. Nitrogen is hardest to retain in soil because 50-70% of nitrogen applied using conventional fertilizers is lost to the soil due to evaporation and leaching as NO2 and NH4. Thus, nitrogen utilization efficiency (NUE) by plants is low and greatly increasing the application cost for supplying nitrogen to the plant.
Further, it is known that water-soluble phosphate can be converted to water insoluble phosphate after reaction with soil minerals, which can result in a decrease of phosphate availability. The forms of reaction products depend on phosphorous sources and soil minerals. In general, Fe-Al-P minerals form in acidic soils containing Fe-Al-oxide minerals, whereas Ca-P minerals form in alkaline or calcareous soils. The phosphorous reaction process involves surface adsorption and/or precipitation. There has been some interest in research and development in modifying the physical characteristics of conventional water-soluble fertilizers to reduce phosphate fixation by soil, and thereby increase the phosphate efficiency for plant uptake.

Calcium is an essential macronutrient for plant growth. Calcium is needed by plants for cell growth and division, for the growth of root tips and shoot tips, the retention of leaves and as an integral part or the cellular structural integrity. Not all fertilizers contain calcium, particularly those having a significant percentage of phosphorus. The simple reason is the formation of calcium-phosphate or hydroxyapatite which makes both the nutrients unavailable for plant nutrition.
Efforts to develop a sustained release fertilizer for nitrogen, phosphate, calcium and micronutrients, have been complicated by the formation of insoluble complexes of micronutrient in the presence of phosphate fertilizer, particularly in acidic and alkaline soil where phosphate is immobilized with iron, aluminum or calcium and hence not immediately available for plants.
Thus, there is still a need in the art to develop a sustained release fertilizer that employs nitrogen, calcium and phosphate. SUMMARY OF THE DISCLOSURE
Accordingly, provided herein is a sustained release fertilizer comprising a modified lignocellulose, wherein the modified lignocellulose is cross-linked with calcium nitrogen and phosphate; wherein the fertilizer is characterized by the structure of formula (I):

wherein,
Ri and R2 are independently selected from divalent cations, acetate, glucuronate, cellulose-ester, acid soluble lignin, phenylpropionate, soluble oligomeric and monomeric sugar containing mono and di ammonium phosphate;
R3 is selected from hydrogen, methoxide and O-lignin;
R4 is selected from lignin, ammonium phosphate and ammonium phosphate;
M is a metal ion selected from transition metal elements; and
A is a divalent metal ion selected from the metal of group II, group III and group VIII of periodic table.
In another aspect, the present disclosure provides a fertilizer capable of providing a source for nitrogen, phosphorous, calcium and micronutrients wherein the micronutrients are divalent cations essential for plants growth and development.
In yet another aspect, the present disclosure provides a water soluble sustained release fertilizer for better plant nutrient delivery.

In yet another aspect, the present disclosure provides a fertilizer having about neutral pH.
In yet another aspect, the present disclosure provides a fertilizer which can be applied to the soil as a basal dose and no top dressings are required.
In yet another aspect, the present disclosure provides a process for preparing a sustained release fertilizer as provided herein; wherein the process comprises:
(a) solubilizing lignocellulosic biomass in phosphoric acid;
(b) neutralizing the reaction mixture of step (a) to a pH of about 7 by adding a nitrogenous source;
(c) adding to the reaction mixture of step (b) a micronutrient source;
(d) treating the reaction mixture of step (c) by adding calcium peroxide under suitable reaction conditions to get sustained release fertilizer as a residue; and
(e) optionally treating the residue of step (d) with a suitable solvent.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
The features of the present disclosure will become fully apparent from the following description taken in conjunction with the accompanying figures. With the understanding that the figures depict only several embodiments in accordance with the disclosure and are not to be considered limiting of its scope, the disclosure will be described further through use of the accompanying figures:
FIG. 1 illustrates FTIR analysis of sustained release fertilizer according to one embodiment of the disclosure;
Fig 2: illustrates TGA analysis of sustained release fertilizer according to one embodiment of the disclosure;
Fig 3: illustrates nitrogen release rate profile of sustained release fertilizer according to one embodiment of the disclosure;
Fig 4: illustrates phosphate release rate profile of sustained release fertilizer according to one embodiment of the disclosure;
Fig 5: illustrates pH profile of sustained release fertilizer according to one embodiment of the disclosure;

Fig 6: illustrates comparative release rate profile of nitrogen and phosphate of fertilizer according to one embodiment of the disclosure; and
Fig 7: illustrates zinc release rate profile of sustained release fertilizer according to one embodiment of the disclosure. DETAILED DESCRIPTION OF THE DISCLOSURE
Before the methods of the present disclosure are described in greater detail, it is to be understood that the methods are not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the methods will be limited only by the appended Claims.
Where a ränge of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit ofthat ränge and any other stated or intervening value in that stated ränge, is encompassed within the methods. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges and are also encompassed within the methods, subject to any specifically excluded limit in the stated ränge. Where the stated ränge includes one or both of the limits, ranges excluding either or both ofthose included limits are also included in the methods.
Certain ranges are presented herein with numerical values being preceded by the term "about." The term "about" is used herein to provide literal support for the exact number that it precedes, as well as a number that is near to or approximately the number that the term precedes. In determining whether a number is near to or approximately a specifically recited number, the near or approximating unrecited number may be a number which, in the context in which it is presented, provides the substantial equivalent of the specifically recited number.
Sustained release fertilizers containing organic carbon cross-linked with calcium, nitrogen and phosphate, demonstrate a more sustained release rate when compared to Standard nitrogen and/or phosphate fertilizers.
According to various embodiments, the present disclosure provides a sustained release fertilizer comprising a modified lignocellulose, wherein the modified

lignocellulose is cross-linked with calcium nitrogen and phosphate; wherein the sustained release fertilizer is characterized by the structure of formula (I):
wherein,
Ri and R2 are independently selected from divalent cations, acetate, glucuronate, cellulose-ester, acid soluble lignin, phenylpropionate, soluble oligomeric and monomeric sugar containing mono and di ammonium phosphate; R3 is selected from hydrogen, methoxide and O-lignin; R4 is selected from lignin, ammonium phosphate and ammonium sulfonate;
M is a metal ion selected from transition metal elements; and A is a divalent metal ion selected from the group consisting of selected from the metal of group II, group III and group VIII of periodic table. In certain embodiments, lignocellulose is chemically modified by reaction of lignocellulose with phosphoric acid. The lignocellulose may be selected from a group comprising hardwood, soft wood and agricultural residue. In certain embodiments, the lignocellulosic biomass is obtained from the fibrous remains of sugarcane and sorghum or any such material of organic origin. The phosphoric acid may be from a group comprising Ortho phosphoric acid, polyphosphoric acid and an organic phosphate or a combination thereof. In certain embodiments, the phosphoric acid is Ortho phosphoric acid.

The modified lignocellulose is cross-linked with nitrogen by reacting with a nitrogenous source selected from a group comprising urea, biuret, ammonia, methylurea and guanylurea. In certain embodiments, the nitrogenous source is urea or ammonia. Ammonia may be aqueous or gaseous.
Then the nitrogen crosslinked modified lignocellulose is reacted with calcium peroxide to get a modified lignocellulose cross-linked with nitrogen and calcium.
In certain embodiments, the fertilizer according to the present disclosure may further comprises a micro nutrient or a mixture of micronutrients. In a further embodiment. the micro nutrient is selected from a group comprising Zn, Fe, Cu, Mn, Mo, Ni, Co and a combination thereof.
In certain embodiments, the invention disclosure provides an alkaline earth material such as calcium containing solid complex fertilizer, which is partly soluble in water to give precipitate free macronutrients and micronutrient source for plant growth.
The amounts of nutrients present within the sustained release fertilizer as describe herein may vary as follows, where the listed amounts are weight percentages based on the weight of the fertilizer composition:
phosphorus derivative (as P2O5): about 5 wt.% - about 60 wt. %;
nitrogen derivative (as nitrogen): about 6 wt. % - about 30 wt. %;
calcium derivative (as calcium): 5 wt. % - 15 wt. %;
organic carbon: 0.2 wt. % - 5 wt. %; and
micronutrients in a ratio of about 1:10 to about 1:20 relative to the nitrogen present in the fertilizer.
In certain embodiments, the fertilizer comprises nitrogen in an amount from about 15 wt. % to about 55 wt. % or form about 20 wt. % to about 50 wt. % or form about 25 wt. % to about 45 wt. % or from about 30 wt. % to about 40 wt. % or from about 5 wt.% to about 25 wt. %
In certain embodiments, the fertilizer comprises phosphate in an amount from about 10 wt. % to about 55 wt. % or from about 15 wt. % to about 50 wt. % or from 20 wt. % to about 45 wt. % or from about 25 wt. % to about 40 wt. % or from about 30 wt. % to about 35 wt. %.

In certain embodiments, the fertilizer comprises calcium in an amount from about 6 wt. % to about 14 wt. % or form about 7 wt. % to about 13 wt. %.
Depending on the process of preparation, the composition of the fertilizers may be controlled. The alkaline earth material used in one of the complex is calcium hydroxide or calcium chloride preferably in the ränge of 7 to 15% (w/w), preferably in the ränge of 7tol3%(w/w).
In certain embodiments, the fertilizer of the present disclosure may be used in a variety of ways such as seed coating, foliar and soil applications.
In certain embodiments, the fertilizer according to the present disclosure can be applied to the soil as a basal dose and no top dressings are required. The fertilizer according to the present invention has about a neutral pH neutral thereby making phosphate release at a neutral pH and prevent the possibility of crop burning comprising of organic and inorganic materials.
In certain embodiments, the present disclosure provides a process for preparing a sustained release fertilizer as provided herein; wherein the process comprises:
(a) solubilizing lignocellulosic biomass in phosphoric acid;
(b) neutralizing the reaction mixture of step (a) to a pH of about 7 by adding a nitrogenous source;
(c) adding to the reaction mixture of step (b) a micronutrient source;
(d) treating the reaction mixture of step (c) by adding calcium peroxide under suitable reaction conditions to get sustained release fertilizer as a residue; and
(e) optionally treating the residue of step (d) with a suitable solvent.
The lignocellulose used in the process may be selected from a group comprising hardwood, soft wood and agricultural residue. In certain embodiments, the lignocellulosic biomass is obtained from the fibrous remains of sugarcane and sorghum or any such material of organic origin. The phosphoric acid used in the process may be from a group comprising Ortho phosphoric acid, polyphosphoric acid and an organic phosphate or a combination thereof. In certain embodiments, the phosphoric acid is Ortho phosphoric acid.

The modified lignocellulose is cross-linked with nitrogen by reacting with a nitrogenous source selected from a group comprising urea, biuret, ammonia, methylurea and guanylurea. In certain embodiments, the nitrogenous source is urea or ammonia. Ammonia may be aqueous or gaseous.
In step (b), the reaction mixture is stirred for about 12-24 h after the Solution becomes homogeneous. In certain embodiments, the reaction mixture stirred for about 15 h. The neutralization is carried out in such a way that the temperature of the neutralized Solution is preferably less than 90°C. In certain embodiments, the temperature is about 0-30°C. In certain embodiments, the nitrogenous source may be selected from a group comprising urea, biuret, ammonia, methylurea and guanylurea. In certain embodiments, the nitrogenous source is ammonia.
In certain embodiments, the micronutrient source in step (c) is selected from a group comprising micronutrient oxide and micronutrient salt. In certain embodiments, the micronutrient salt is selected from a group comprising micronutrient chloride, micronutrient nitrate and micronutrient phosphate.
In certain embodiments, the reaction mixture in step (d) is heated to about 80-90°C after the addition of calcium peroxide. In certain embodiments, the temperature is about 90°C.
In certain embodiments, the solvent used in step (e) is selected from a group comprising one or more alcohols selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, and n-butanol; and a ketone selected from the group consisting of acetone, methyl ethyl ketone and methyl isobutyl ketone. In certain embodiments, the solvent is methanol or acetone.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the disclosure belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present disclosure, preferred methods and materials are described. For the purposes of the present disclosure, the following terms are defined below.

The articles "a" and "an" are used herein to refer to one or to more than one (i.e. to at least one) of the grammatical object of the article. By way of example, "an element" means one element or more than one element.
As used herein, the term "comprises" or "comprising" is generally used in the sense of include, that is to say permitting the presence of one or more features or components.
Cross-link can include covalent bonds, ionic bonds, electrostatic bonds, Vander Waals bonds and hydrogen bonds.
As used herein, "nutrient" refers to both micronutrients and macronutrients. Non-limiting examples of nutrients include zinc, copper, manganese, boron, calcium, iron, calcium, magnesium, molybdenum, Silicon, selenium, phosphate, nitrogen, potassium and sulfur.
As used herein, "micronutrients" refer to elements required in small or trace amounts for plant growth. Non-limiting examples of micronutrients include molybdenum, nickel, copper, zinc, manganese, boron, iron and chloride.
As used herein, "macronutrients" refer to elements typically required in large amounts for plant growth. Non-limiting examples of macronutrients include sulfur, phosphorus, phosphate, magnesium, calcium, potassium, nitrogen, oxygen, carbon and hydrogen.
As used herein, "nutrient use efficiency fertilizer (NUE)" refers to the fertilizer products that can reduce nutrient loss to the environment while increasing the nutrient availability for the plant or crop.
The present disclosure is further described with reference to the following examples, which are only illustrative in nature and should not be construed to limit the scope of the present disclosure in any manner. EXAMPLES EXAMPLE 1:
To 10.0 g of 0.2 mm sieved sweet sorghum bagasse in a glass beaker, gradually added 380 ml of o-phosphoric acid (85%) with continuous stirring until mixture becomes homogeneous and prolonged the reaction for 15 h at room temperature. Then the reaction mixture was neutralized to a pH of 7 by adding aqueous ammonia (25%) in an

ice-bath. Then freshly prepared calcium peroxide Solution (250 mL) was added at room temperature and the resulting mixture was heated to 90°C for 2 h for cross-linking. The reaction mixture was cooled to ambient temperature and filtered to get a residue. The residue was washed with acetone and dried in oven at 85°C. The compositional analysis of the Product I was depicted in table 1 below.
Preparation of Calcium peroxide Solution: 40.0 g of calcium chloride (fused) was dissolved in 150 ml of distilled water and added gradually 100 ml of H2O2 (30% w/v), stirred for 20 min to form calcium peroxide Solution.
EXAMPLE 2:
To 10.0 g of 0.2 mm sieved sweet sorghum bagasse in a glass beaker, gradually added 380 ml of o-phosphoric acid (85%) with continuous stirring until mixture becomes homogeneous and continued the reaction for 15 h at room temperature. Then the reaction mixture was neutralized to pH 7.0 by adding aqueous ammonia (25%) in an ice-bath. Then 14 gm of ferrous sulphate and 6.3 g of zinc oxide were added at continuous stirring and heated until a clear Solution was obtained. Then freshly prepared calcium peroxide Solution (250 mL) was added at room temperature and the resulting mixture was heated to 90°C for 2 h for cross-linking. The reaction mixture was cooled to ambient temperature and filtered to get a residue. The residue was washed with acetone and dried in oven at 85°C. The compositional analysis of the Product II was depicted in table 2 below.

CHARACTERIZATION OF COMPOUNDS OF FORMULA (I) FT-IR:
FT-IR spectrum of Product I characterized by a structure of formula (I) was shown in Fig. 1. The characteristic absorption bands at 3131 cm"1 and 3107cm"1 corresponds to stretching vibrations of O-H and N-H groups. Peaks at 1441 cm"1 and 1402 cm"1 correspond to stretching vibrations of ammonium phosphate P-0-(N) group. The bands observed at 1019, 943 and 894 cm"1 corresponds to stretching and bending vibrations of PO4"3 group. THERMOGRAVIMETRIC ANALYSIS (TGA)
Thermal stability of fertilizer characterized by a structure of formula (I) was examined using TGA from 30 to 800°C at a rate of 10°C/min under nitrogen atmosphere. The TGA and its derivative curve shows thermal behavior of materials using on-set decomposition temperature and at which various weight loss of sample was recorded. The initial stages between 30 to 140°C, the loss was observed due to the elimination of water molecules/combustible gases. In second stage between 140-225°C, the loss was observed due to the elimination of strongly bonded water and may be elimination of phosphate molecules. In the final stage, between 230-650°C indicates that degradation of Compound and remaining weight is indication of metals and ash (Fig. 2).

NUTRIENT RELEASE STUDY
Leaching columns were used to quantify the release of macronutrients such as nitrogen and phosphate over time. Acid treated neutralized soil sample of 2 mm packed in a tubulär column of approximately 5 x 50 cm and column is attached with tubing firom the bottom to collect the leachate. Immediately, after adding the fertilizer on top of the column, water was added at a constant rate so that the top of the column remains moistened. Samples collected at different interval and analyzed.
Percent release and retention of nitrogen of Product I were measured. Table 4 and Fig.3 showed that even after 150 h nearly 23% nitrogen retained in the Compound of product I

EXAMPLE 4:
Percent release and retention of phosphorous of Product I were measured. Table 5 and Fig.4 showed that even after 72 h nearly 40% phosphate retained in the Compound of Product-I.
EXAMPLE 5:
As shown in Fig. 5, the pH profile of the fertilizer characterized by a structure of Product I of the present disclosure was measured during leaching experiment for nearly 150 h and the pH during the entire time noted at nearly 6.5. EXAMPLE 6:
The nitrogen release behavior of Product I was compared with Standard nitrogen urea and DAP. It was noted that the fertilizer of the present disclosure continued to

release the nitrogen even after 150 h of study whereas nitrogen release from the Standard fertilizer urea or DAP depleted after 60 and 70 h. Similarly, the phosphate release behavior of Product I was compared with Standard phosphate fertilizers (DAP). Product I continuously releasing phosphate at a higher rate than DAP as shown in Fig. 6. EXAMPLE 7: RELEASE OF MICRONUTRIENTS
As seen in Fig. 7, about 20% of zinc is released over 72 h from product I. EXAMPLE 8: FIELD TRIAL DATA
To evaluate the Performance of the products, field trials were conducted at Directorate of Rice Research, Hyderabad, India on rice for both kharif and rabi seasons. Randomized block of size 4 mt x 3 mt selected for the study. The Product I was applied as a single basal application and compared with the Standard fertilizer application and no fertilizer application. Except for supplementing nitrogen at basal dose to compensate the amount of nitrogen at the basal dose, other conditions remain same for all the applications. The harvested data clearly showed the grain yield was superior to the recommended doses of fertilizers and even at application of 50% of the present fertilizer, the yield is similar or better than the recommended doses of fertilizer application wherein there is nearly 20% increase in grain yield compared to the recommended fertilizer dose (120: 60: 40 kg /ha NPK at 100% dose). The straw yield was also increased significantly over the control.

# As per recommended practices (1 basal and 2 splits) % GY*= Percentage of grain yield over controls MOP = Murate of potash
The field trial data showed that overall grain yield in rice was increased by more than 20% compared to the recommended dose of fertilizer. Further, even at 50% of the present fertilizer as basal dose showed superior results than that of 100% recommended dose (1 basal + 2 splits).
ADVANTAGES OF THE PRESENT INVENTION
1. The fertilizer of the present disclosure provides nutrients for an extended period
of time compared to individual nitrogen and/or phosphate fertilizers or any known fertilizers and found to provide better growth and yields in plants when used in a variety of ways such as seed coating, foliar and soil applications.

2. The fertilizer of the present disclosure is precipitate free, and water soluble which provides nutrients to the plants for an extended period of time.
3. The fertilizer of the present disclosure has neutral or about neutral pH to protect the plants from acid burns.
4. The fertilizer of the present disclosure can be used as a single application.
5. Availability of micronutrients in the presence of phosphate is maximum.
Although the foregoing disclosure has been described in some detail by way of illustration and examples for purposes of clarity of understanding, it is readily apparent to those of ordinary skill in the art in light of the teachings of this disclosure that certain changes and modifications may be made thereto without departing from the spirit or scope of the appended claims.
Accordingly, the preceding merely illustrates the principles of the disclosure. It will be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the disclosure and are included within its spirit and scope. Furthermore, all examples and conditional language recited herein are principally intended to aid the reader in understanding the principles of the disclosure and the concepts contributed by the inventors to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all Statements herein reciting principles, aspects, and embodiments of the disclosure as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents and equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure. The scope of the present disclosure, therefore, is not intended to be limited to the exemplary embodiments shown and described herein. Rather, the scope and spirit of present disclosure is embodied by the appended claims.

WE CLAIM:
1. A sustained release fertilizer comprising a modified lignocellulose, wherein the
modified lignocellulose is cross-linked with calcium, nitrogen and phosphate; wherein the sustained release fertilizer is characterized by the structure of formula
wherein,
Ri and R2 are independently selected from divalent cations, acetate, glucuronate, cellulose-ester, acid soluble lignin, phenylpropionate, soluble oligomeric and monomeric sugar containing mono and di ammonium phosphate;
R3 is selected from hydrogen, methoxide and O-lignin;
R4 is selected from lignin, ammonium phosphate and ammonium sulfonate;
M is a metal ion selected from transition metal elements; and
A is a divalent metal ion selected from the metal of group II, group III and group VIII of periodic table.

2. The sustained release fertilizer as claimed in claim 1, wherein the modified lignocellulose is a substance chemically modified by reaction of lignocellulose with phosphoric acid.
3. The sustained release fertilizer as claimed in claim 2, wherein the phosphoric acid is Ortho phosphoric acid.
4. The sustained release fertilizer as claimed in claim 1, wherein the modified lignocellulose is cross-linked with nitrogen by reacting with a nitrogenous source selected firom a group comprising urea, biuret, ammonia, methylurea and guanylurea.
5. The sustained release fertilizer as claimed in claim 4, wherein the nitrogen crosslinked modified lignocellulose is reacted with calcium peroxide to get a modified lignocellulose cross-linked with nitrogen and calcium.
6. The sustained release fertilizer as claimed in claim 1, may further comprises a micronutrient or a mixture of micronutrients.
7. The sustained release fertilizer as claimed in claim 6, wherein the micronutrient is selected from a group comprising Zn, Fe, Cu, Mn, Mo, Ni, Co and a combination thereof.
8. The sustained release fertilizer as claimed in claim 1, wherein the fertilizer comprises at least one nutrient from the nutrients listed below:
phosphorus derivative (as P2O5): about 5 wt.% - about 60 wt. %; nitrogen derivative (as nitrogen): about 6 wt. % - about 30 wt. %; calcium derivative (as calcium): 5 wt. % - 15 wt. %; organic carbon: 0.2 wt. % - 5 wt. %; and
micronutrients in a ratio of about 1:10 to about 1:20 relative to the nitrogen present in the fertilizer.
9. The sustained release fertilizer as claimed in claim 1, wherein the fertilizer
application is a basal application.
10. The sustained release fertilizer as claimed in claim 1, wherein the fertilizer
application is a single dose basal application.
11. The sustained release fertilizer as claimed in claim 1, wherein pH of the fertilizer
is about neutral pH.

12. A process for preparing a sustained release fertilizer as claimed in claim 1;
wherein the process comprises:
(a) solubilizing lignocellulosic biomass in phosphoric acid;
(b) neutralizing the reaction mixture of step (a) to a pH of about 7 by adding a nitrogenous source;
(c) adding to the reaction mixture of step (b) a micronutrient source;
(d) treating the reaction mixture of step (c) by adding calcium peroxide under suitable reaction conditions to get sustained release fertilizer as a residue; and
(e) optionally treating the residue of step (d) with a suitable solvent.

13. The process as claimed in claim 12, wherein the lignocellulosic material may be from a group comprising hardwood, soft wood and agricultural residue.
14. The process as claimed in claim 13, wherein the agricultural residue is selected from a group comprising sweet sorghum and sugar cane bagasse.
15. The process as claimed in claim 12, wherein the phosphoric acid is ortho-phosphoric acid.
16. The process as claimed in claim 12, wherein the reaction mixture in step (a) is stirred for about 15 h after the Solution becomes homogeneous.
17. The process as claimed in claim 12, wherein neutralization is carried out in such a way that the temperature of the neutralized Solution is preferably less than 90°C.
18. The process as claimed in claim 12, wherein the nitrogenous source in step (b) is selected from a group comprising urea, biuret, ammonia, methylurea and guanylurea.
19. The process as claimed in claim 18, wherein the nitrogenous source is ammonia.
20. The process as claimed in claim 12, wherein the micronutrient source in step (c) is selected from a group comprising micronutrient oxide and micronutrient salt.
21. The process as claimed in claim 20, wherein the metal salt is selected from a group comprising metal chloride, metal nitrate and metal phosphate.
22. The process as claimed in claim 12, wherein the reaction mixture in step (d) is heated to about 80-90°C after the addition of calcium peroxide.

23. The process as claimed in claim 12, wherein the solvent in step (e) is selected from a group comprising one or more alcohols selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, and n-butanol; and a ketone selected from the group consisting of acetone, methyl ethyl ketone and methyl isobutyl ketone.
24. The process as claimed in claim 23, wherein the solvent is methanol or acetone.
25. A sustained release fertilizer obtained by the process as claimed in any of the Claims 12-24.