D. C. JOSHI* AND C. P. GHONSIKAR** Agricultural Experimental Station, Durgapura, J aipur ABSTRACT

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1 Annals f Arid Zne-20 (2), ,1981 Dis1:ribu1:in f 1:1:aland humus phsphrus rela1:in 1:0 sme sil charac1:eris1:ics in D. C. JOSHI* AND C. P. GHONSIKAR** Agricultural Experimental Statin, Durgapura, J aipur ABSTRACT Cntent and distributin f ttal phsphrus and different frms f rganic phsphrus have been studied in sme typical sil prfiles f Rajasthan. Mst f the rganic phsphrus was assciated with nn-humic fractin fllwed by fulvic acid and humic acid. Humin did nt cntain any phsphrus. Humic and fulvlc acid bund phsphrus increased with rganic carbn and clay+silt cntent f the sil but the relatinship was nt significant. Significant crrelatin between phsphrus assciated with humic and fulvic acid and als between rganic phsphrus and nn-humic phsphrus fractin indicated assciatin <:mng sme cmpnents f these fractins. INTRODUCTION Organic phsphrus thrugh gradual mineralisatin is the ptential surce f phsphrus supply t plants. Thugh rganic phsphrus is related with sil carbn cntent yet wide variatins in rganic carbn/rganic phsphrus ratis have been btained in different sils (Kaila, 1963). Barrw (1961) characterized the phsphrus cmpunds in sil as humic and nn humic fractin. In the study f sme Rajasthan sils Jshi and Saxena (1972) bserved that 30 t 86 per cent f rganic phsphrus was fund assciated with nn humic fractin fllwed by ~ - humus, fulvic acid and humic acid. Bhandari and Saxena ( 1970) reprted narrw rganic carbni rganic phsphrus ratis fr Rajasthan sils, thus indicating higher rganic phsphrus mineralizatin ptential. Present study was taken up t find ut the distributin f ttal and rganic phsphrus in sme Rajasthan sil prfiles in relatin t sme sil characteristics. MA TERIAL Present address: "'Central Arid Zne Research Institute, Jdhpur. """Marathawara Agricultural University, Parbhani. AND METHODS Fr the purpse f present study eight prfiles representing different sil grups were cllected and analysed fr physic chemical characteristics by usual methds. Humic and fulvic acid fractins were separated accrding t prcedures described by Knnva (1966). Ttal, rganic and inrganic phsphrus in sil was determined accrding t

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6 142 : D. C. JOSHI AND C. P. GHONSIKAR Mehta et ai. (1954). Phsphrus cntent f humus fractins was determined using Dickman and Bray's (1940) prcedure. RESULTS AND DISCUSSION Physic chemical characteristics and ttal and humus bund phsphrus cntent f sils are given in Tables 1 and 2. Organic carbn cntent was lw in Jaipur and Ganganagar (0.130 t per c~'nt), medium in Sirhi, Banswara and Kta (0.170 t per cent), and high in Udaipur and Chittrgarh (0.561 t per cent) prfiles. These sils are generally medium t fine textured except J aipur prfile which is mderately carse textured. Ttal phsphrus ranged frm 80 t 540 ppm (Table 2). In general the ttal phsphrus decreased with depth except in Jaipur, Sirhi and Banswara (red) sils. Increase f ttal phsphrus with depth in latter sils may be attributed t the illuviatin f clay and silt. Desert sils f Jaipur, Ganganagar and Sirhi in spite f medium t carse texture and lw rganic matter cntent cntained higher amunt f ttal phsphrus. Gupta (1950) and Pareek and Mathur ( 1969) als reprted aelian sils f desert regin t be rich in ttal phsphrus. Ttal phsphrus was lwest ( ppm) in Banswara and Chittrgarh prfiles fllwed by Udaipur and Kta sils ( ppm). Organic phsphrus was fund t range frm 76 t 430 ppm. Sirhi, Chittrgarh and Kta prfiles cntained mre rganic phsphrus than ther sils. Higher rganic phsphrus cntent in surface hrizns f Udaipur, Chittrgarh and Banswara (black) was due t higher rganic matter. In Jaipur, Ganganagar and Banswara (black) prfiles rganic phsphrus cntributed per cent f ttal phsphrus. Distributin f rganic phsphrus was fund t fllw the trend f rganic carbn and clay but the crrelatin with these cnstituents was nt significant (r= 0.112, r = ) indicating the effect f ther factrs n rganic phsphrus accumulatin. Organic phsphrus cntent in different sils ranged frm 40 t 450 ppm and cestituted 30 t 85 per cent f ttal phsphrus. Jaipur and Ganganagar sils cntain mre inrganic phsphrus (260 t 450 ppm) than ther sils (40 t 260 ppm). Mehta et ai. (1971) als reprted that 50 t 90 per cent f ttal phsphrus was assciated in sme sils f western Rajasthan with inrganic frms. Narrw rganic carbni rgani::: phsphrus rati f 8 t 39 indicated higher phsphrus mineralisatin ptential. Slightly wider ratis (50 t 202) were btained fr Udaipur, Chittrgarh and Banswara sils cntaining higher rganic carbn. Mahendra Singh and Arra (1967) and Bhandari and Saxena (1970) als reprted CIP rati 37 t 46 and 30 t 290 fr Punjab, Haryana and Rajasthan sils, respectively. Mst f the rganic phsphrus was fued assciated with nn humic fra ::;- tin (47 t 1 per cent). Humus bunj phsphrus varied frm traces t as high as 53 per cent in sme cases. Higher amunt f phsphrus assciated with nn humic fractin can be due t the accumulatin f phytin type f cmpunds particularly insitl hexa phsphate, which are insluble in alkaline extracts. Similar findings were als reprted by Bhandari and Saxena (1970). Phsphrus was nt detectable in the humin fractin f these sils. This is in agree-

7 P DISTRIBUTION IN SOILS : 143 ment with the results reprted by Jshi and Saxena (1972) and Smani (1974). Ganganagar, Jaipur, Banswara black, Sirhi and Kta sils shwed 0.02 t per cent phsphrus assciated with humic acid and 2.91 t 9.42 per cent assciated with fulvic acid. Phsphrus assciated with bth these fractins shwed decrease with depth except in secnd layer f Sirhi prfile which appears t be due t higher amunt f rganic carbn. Humic acid P/fulvic acid P rati ral2ged between 0.04 t 0.65 and decreased with depth. Udaipur, Banswara red and Chittr prfiles shwed 0.78 t and 1.52 t 40.2 per cent phsphrus assciated with humic and fulvic acid fractin respectively. Humic acid P/fulvic acid P rati in these prfiles ranged frm 0.09 t 0.87 except the secnd layer f Banswara red prfile which shwed a rati as high as Higher amunt f humus bund phsphrus culd be due t higher.,,. I l 40.'. 7 -II" 1 1'\,1 rganic matter cntent f these sils. Data n the amunt f phsphrus assciated with humus fractins are cmparable t thse f Yshida (1940) and Bwer (1945). Fig. shws that with increasing rganic carbn, there was an increase in humic and fulvic acid assciated phsphrus thugh rganic phsphrus and nn humic phsphrus did nt fllw this trend. Williams and Saunders (1956) reprted.that phsphrus esters are assciatedmainly with the clay and silt fractins. Increase in rganic phsphrus and nn humic phsphrus was bserved with increase in fine fractin (silt + clay). Mre humic and fulvic acid assciated phsphrus in sils cntaining 31 t 50 per cent finer fractin appears t be due t better physical cnditins fr rganic matter transfrmatins. Saxena and Kashinathan (1956) als bserved higher levels f phsphate esters in clays and lams than in light textured sil. ~~~... 0-'- II.... ACCl. D'~.fICCI -2',. ~ ~ -15,;),.75 OIt te c.. e.ll ('.re."') FIG S 0If -.us FORMS r PHOSP>tOflIJS If' RECATIOt/ TO Itt.T. CLAY AIlIO 0RG4HIC C~ PERCf~T

8 144 : D. C. JOSHI AND C. P. GHONSIKAR Significant crrelatin between rganic phsphrus and nn humic phsphrus (r = 0.718) indicated that nn humic phsphrus was the predminant frm. Als significant crrelatin between humic and fulvic acid bund phsphrus (r= ) revealed a degree f equilibrium between these frms. Wide variatin in phsphrus cntent f humus fractins and nn significant crrelatin f rganic phsphrus with humic and fulvic acid bund phsphrus(r=-0.326, r = ) pinted ut assciatin f a large range f phsphrus c0'1lpunds v.!iththese fractins. ACKNOWLEDGEMENT Authrs are thankful t the Directr f Agriculture, Rajasthan, Jaipur, fr facilities. REFERENCES Andersn, G A partial fractinatin f alkali sluble sil rganic phsphate. J. Sil Sci. 12: Barrw, N. J Phsphrus in sil rganic matter. sils fertil. Herpanden 24: Bhandari, H. C. and Saxena, S. N Nature f rganic phsphrus cmpunds in sme sils f Rajasthan. J. Indian Sc. Sil Sci. 18: Bwer, C. A Separatin and identificatin f phytin and its derivatives frm sils. Sils Sci. 59: Dickman, S. R. and Bray, R. H Clrimetric determinatin f phsphate. Ind. Eng. Chern. Ed. 12: Jshi, D. C. and Saxena, S. N Distributin f rganic phsphrus in humus fractins. J. Indian Sc. Sil Sci. 20: Kaila, A Organic phsphrus in Finnish sils. Sil Sci. 95: Knnva, M. M Sil rganic matter. Pregman Press Ltd., Oxfrd. Mahendra Singh and Arra, S. K Phsphrus in sils f Punjab and Haryana. J. Indian Sc. Sil Sci. 17: Mehta, N. c., Legg J. O. 1., Gring, C. A. 1. and Black, C. A Determinatin f rganic phsphrus in sils. 1. Extractin methd. Sil Sci. Sc. Arne. Prc. 18: Mehta, P. c., Puntamkar, S. S. and Seth, S. P Vertical distributin f phsphrus in sils f western Rajasthan. J. Indian Sc. Sil Sci. 19: Pareek, B. L. and Mathur, C. M Available and ttal phsphrus status f sils f Rajasthan. J. Indian Sc. Sil Sci. 17: Saxena, S. N. and Kashinathan, S Organic phsphrus cntent as an index f fertility f sme Indian sils. Prc. Nat. A cad. Sci. India 25A: Smani, L. L Studies n the cmpsitin, transfrmatin and rle f rganic matter in sme irrigated areas. Ph.D. Thesis, University f Udaipur, UdaipJ.lr. Williams, E. G. and Saunders, M. H Distributin f phsphrus in prfile and particle size fractin f sme scttish sils. J. Sil Sci. 7: Yshida, R. K Studies n rganic phsphrus cmpunds in sil; islatin f insitl. Sil Sci. 50: