Chemistry: fertilizers – Processes and products – Organic material-containing
Reexamination Certificate
1999-03-05
2002-01-08
Langel, Wayne (Department: 1754)
Chemistry: fertilizers
Processes and products
Organic material-containing
C071S058000, C071S064070, C071S064110, C071S902000
Reexamination Certificate
active
06336949
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a slow release urea fertilizer composition and a process for the preparation of the said composition. More particularly, the invention relates to a slow release urea fertilizer composition and process for the preparation of the said composition wherein coating of a nitrogenous fertilizer with essential oils or their derivatives acts as a cheap and potential urease
itrification inhibitor.
BACKGROUND OF THE INVENTION
Nitrogen is considered to be one of the most vital agricultural inputs in crop production. It is estimated that the present global consumption of fertilizer nitrogen is of the order of 77 Tg annually which is likely to be increased to 144 Tg by 2000 AD. The present consumption of fertilizer N in India, of which urea comprises 80%, is about 9.5 million tons, which is estimated to be enhanced to about 14 million tons by the end of this century to produce about 225 million tons food grains. Fertilizer N use efficiency seldom exceeds 50% in arable crops; the utilization efficiency is even less under rainfed conditions, It is further less in paddy (20-30%) where fertilizer losses are greatest. In addition to the large amount of fertilizer N needed, high cost involved in their production or purchase also need to be considered. Thus, efficient use of fertilizer N is necessary, suggesting that regulation of N transformations in soil have a major role to play.
Fertilizer urea when applied to soil is hydrolyzed by enzyme urease to form NH
4
and finally to NO
3
which is prone to losses through denitrification and leaching. The NH
4
is subjected to losses through volatilization. Apart from increasing the cost of cultivation in agriculture, N loss through leaching as well as in gaseous forms has direct concern in environmental degradation. As a consequence of leaching NO
3
concentration in ground water has been increasing at an alarming rate. Any technique that can restrict or retard these processes would reduce the loss of N. The present invention deals with finding strategies for retarding urea transformation and nitrification for a higher fertilizer N use efficiency.
PRIOR ART REFERENCE
Lot of research works have been done on management strategies for improving utilization efficiency of nitrogenous fertilizers specially urea which accounts for about 80% consumption of the total nitrogenous fertilizers. A number of review articles have dealt with the environmental, chemical and physical factors affecting the hydrolysis of urea in soil (Gould et al 1986, Adv. Akgron. 40:209-238). Urease inhibitors and methods of controlling urea transformation in soil were thoroughly reviewed by several workers (Sahrawat 1980, Plant Soil 57:335-252, Mulvaney and Bremner 198, Soil Biol. Biochem. 5:153-190). Review of Martens and Bremner (1984) gives an account of inhibitors like phosphorodiamidates and phosphorotriamides which have been found effective in several conditions (Soil Sci. Soc. Am. J. 48:302-305). Several sulfhydryl reagents, hydroquinones, catechol, P-benzoquinones, dihydric phenols. aminocresol have been found to restrict hydrolysis of urea (Rodgers, 1984, Plant Soil 79:115-158). The efficacy of hydroxamic acids has been studied as urease inhibitors but it has not been found very effective for a long period (Pugh and Waid 1969, Soil Biol Biochem. 1:195-206).
Compounds that have structural similarities to urea inhibit urease by competing the same active site on the enzyme. Thio-urea, methyl urea and the substituted phenylurease are known inhibitors of urease. Ash worth et al (1980) measured urea hydrolysis and nitrification inhibition in soil by a number of xanthalates (Soil Sci. Soc. Am. J. 44:1247-1251). Neither the substituted urease nor the xanthalates provide sufficient inhibition of soil urease to be of practical agricultural value. Several phosphoroamide class of compounds have been tested but only few have been examined as potential under some specific environmental and edaphic conditions. Urea has been coated Nvitli resin, plastic shellac, silica and sulphur and impregnated with petroleum wax in order to retard the dissolution of urea in the soil. Sulphur coated urea has been found most effective among the coated fertilizers but its main disadvantages are higher cost than soluble nitrogenous fertilizers and soil acidification due to formation of H
2
SO
4
.
Another slow release urea fertilizer is produced by polymerization or condensation of urea with an aldehyde. Crotonylidinediurea ((CDU) and isobuitlidene diurea (IBDU) are zo slow release nitrogen sources produced by the condensation of two urea and two aldehyde molecules (Gould et al 1986, Adv.Agron. 40:209-238). IBDU have been found superior to SCU under field conditions.
In order to reduce volatilization of ammonia urea has been mixed with other chemicals such as ammonium polyphosphate, phosphoric, boric and nitric acid (Mudrock and Frye, 1985, Adv. Agron. 77:630-633). Similarly urea-thiourea mixtures placed in either bands or pellets have been used to retard the transformation of urea in the soil. Thiourea is both a weak urease and nitrification inhibitor; alone it has been utilized as a slowly available source of both sulphur and nitrogen (Malhi and Soper 1981, Agron. J. 73:991-995). Nitrification inhibitors are the materials which restrict the microbiological oxidation of armonium to nitrate thereby reducing the loss of N by leaching and denitrification. The literature on nitrification inhibitors is very extensive (Prasad et al. 1971, Adv. Agron. 23:337-383, Sahrawat and Keeney 1985, Commu. Soil Sci. Pl. Anal. 16:517-524; Sahrawat 1989, Adv. Agron. 42:279-302). These reviews cover various aspects of the effects of nitrification inhibitors on retardation of nitrification in soil and crop production. In a recent revies Prasad and Power (1995) provides an overview of the status on the use of nitrification inhibitors in relation to productivity, human and animal health and the environment (Adv. Agron. 54:234-281). The interest in nitrification inhibitors followed the development of nitrapyrin (2-chlor-6-(trichloromethyl pyridine) by the DOW chemical company USA as an effective inhibitor of nitrificanon. Subsequently a series of chemicals viz. BHC. sodium azide sodium chlorate. dicyanodiamide (DCD), thiourea AM (2-amino-4 chloro-6 methyl prindine), ATC (4 amino-1,2,4 tnazole), N-serve etc. have been identified as nitrification inhibitors (Sahrawat et al 1989, Adv. Agrron. 42:279-309). Use of most of these chemicals have been restricted to academic experimental stage because of their difficult availability, higher cost and adverse effect on soil processes. Allelochemic inhibition of the process of mineralization and nitrification has been reported to occur in many ecosystem (White 1986, Biol. Fert. Soil 2:97-104). Polyphenols particularly tannins and organics which are water soluble and volatile are presumed to have N-inhibitory properties: Karanjin from Karanj (Pongamia glabra) and tea waste have been reported to retard nitrification (Sahrawat et al 1989, Adv. Agron. 42:279-309). Medicinal plant products like Pyrethrum flower (Crvsanthaxium cinerariefolium) waste have also been found to have this property (Ram et al 1993, Indian Soc. Soil Sci. 41:176-177).
Researches being carried out in India on inhibitors have been reviewed by Prasad et al (1971, Adv. Agron. 23:337-383 and Sahrawat et al 1989, Adv. Agron. 42:279-309). Lac-coated urea (LCU) has been effectively evaluated by Bhowmik (1980, Fert. News 25:17-19). Dissolution rate of LCU has been found to be more or less equal to sulphur coated urea. The pioneering works in India on this aspect include that of Prasad and Rajale (1972, Soil Biol Biochem. 4:450-457), and Sahrawat et al (1989, Adv. Agron, 42:279-309), who reported inhibitory properties in Karanj (Pongamia glabra) and Neem (Azadirachta indica). Neem cake coated urea besides having slow releasing properties had additional beneficial effect in inhibiting nitrification in soil.
OBJECTS OF THE INVENTION
The main objective of the present invention is the
Agarwal Krishna Kumar
Anwar Mohammad
Khanuja Suman Preet Singh
Kiran Usha
Kumar Sushil
Council of Scientific & Industrial Research
Langel Wayne
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