Distribution of micronutrient forms along duny landscape

Transcription

1 Annals f Arid Zne-22 (2), , 1983 Distributin f micrnutrient frms alng duny landscape D. C. JOSHI AD R. P. DHIR Central Arid Zne Research Institute, Jdhpur ABSTRACT Different frms f Fe,?vln, Zn and Cu in duny landscape f tw rainfall ZOnes f Indian arid regin have been reprted. The dune and interdunal sils f higher rainfall zne cntained mre f HCl sluble :-'In, Zn and Cu; free Fe and Mn; reducible and active Mn and DTPA Mn than their cunter parts in the lw rainfaii ZOne. In bth the rainfan zjnes, interdunal sils cntained higher amunts f these cnstituents. DTPA Fe and Zn were mre in the dune sils f lw rainfaii znes and in bth the iainfall znes interdunal sils cntained less amunts than the assciated dunes. Mst f these sils appeared weii prvided with the irn, cpper and zinc but deficient in manganese cntent. ITRODUCTIO While studying the landuse pattern f western Rajasthan, Sen (1978) bserved that thugh dunes are classified as sandy waste, they are always nt waste. The lwer and middle flanks f these dunes are cultivated during the years f gd rainfall, particularly in the rainfall zne f abve 2 mm. Upper flanks and crests f dunes serve as grazing grund t the livestck. Krishnan et al. (1966) bserved that during summers high moisture cntent ccurs belw 1.5 metre depth in unstabilized and belw 4 metres in stabilizt:d dunes. These active dunes duc t presence f sufficient misture prvide favurable cnditins fr stabilizatin f suitable plant species. Saxena and Singh (1976) and Muthana (1976) have suggested lcally adapted indigineus species like Callignum plygnides, Acacia senegal, Acacia trtilis, Prspis cineraria, Lasiurus sindicus and Saccharum munj fr planting n dunes fr their stabilizatin. Dune sands are generally regarded infertile. Dhi r (1976) reprted that these are extremely lw in rganic carbn and have medium status f phsphrus and ptassium. In the present paper distributin f different frms f micrnutrients in sands f varying types f dunes and sandy plain f arid parts f Rajasthan have been reprted. EXPERIMET AL Sil prfile samples f different types f dunes, interdunes and sandy plain frm extremely arid part (1 t 2 mm rainfali) and frm arid t semi-arid, trans itinal (4-5 mm rainfall) were cllected. The samples were passed

2 136 : D. C. JOSHI AD R. p. DHIR thrugh 2 mm sieve and then analysed fr ph and electrical cnductivity (1 : 2 sil water rati), CaC0 3 and rganic carbn by usual methds (Jacksn, 1958; Piper, 1950). Fr extractin f different frms f micrnutrients fllwing methds were adpted: 1. HCI sluble micrnutrients- A. E. A. prvisinal methd (Piper, 1950). 2. Free Fe and Mn - Mehr aand Jacksn (1960). 3. Reducible Mn-I Ammnium acetate+0.2% hydrquinne (Jacksn, 1958). 4. Exchangeable micrnutrients - I Ammnium acetate extractable (Jacksn, 1958). 5. Active Mn - Reducible + Exchangeable. 6. Available extractable 1978). RESULTS AD DISCUSSIO The dune ecsystem micrnutrients - DTPA (Lindsay and rvel1, Micrn utrients in all these extracts were determined using varian Techtrn Atmic absrptin spectr-phtmeter. Mean values f different frms f the micrnutrients are reprted in Tables 1 and 2. The climate f the Indian arid zne is f the dry trpical type. The mean annual rainfall varies frm less than 1 mm in the nrth west f Jaisalmer t 450 mm at the eastern bundary which ccurs frm mid June t mid September. The mean maximum temperature during summer ges t 40 C, the highest being 48 t 50 C. In winter temperature drps t 14 t 15 C in December-January with abslute minimum rarely less than 4 C. In lw rainfall znes ( < 2 mm) the surface f the dunes is very much disturbed resulting in large amunt f lse sand. In sme cases the flanks f lngitudinal and parablic dunes are cvered with desert scrub. The sand dunes in rainfall znes f 3 t 4 mm are stabilized and supprt mixed xermrphic wd land instead f psammentphytic scrub. The dunes are frmed f the lse sand cnsisting f 60 t 75 per cent grains f 0.06 t 0.12 mm size. They cnsist f 63.7 t 87.3 per cent fine sand, 11.3 t 30.3 per cent carse sand, 1.8 t 4.5 per cent clay and 0.4 t 3.1 per cent silt (Dhir, 1976). The dune sils ccurring in higher rainfall zne shwed lwer ph ranges ( ), are devid f CaC0 3 and als cntain slightly mre f rganic carbn ( %) in cmparisn t thse ccurring in lw rainfall znes (ph, ; CaC % and O.c. negligible t 0.03%). In bth the rainfall znes values f ph and rganic carbn were fr dunes, ph 7.8 t 9.1; O.C. 0.Q1-0.06%), interdunes, ph C % and sandy plain, ph ; O.C %. DISTRIBUTIO OF FORMS OF IRO AD MAGAESE The HCI sluble Fe varied frm 0.78 t 1.23 per cent in different sils. It was

3 MICROUTRIET FORMS I DUY LADSCAPE 137 «: - Mō.,.. d d -< 0) c..; f-< ::l a E VI 0-0 '" a E n M V - I n ~ ::: c ~ :::.~ 0- r- M n r-: -- n 'l:i M, 'l:i r- r- vi -...;

4 138 D. C. JOSHI AD It. P. DHIR... <'I ci 0- Ṇ......: e-. 0. c: E E n V ci v; $! '0 V> E U "0 c: <IS U c:... E.. :2 c:.. ~ "0... '"C tl C u u c:... \0 Ṇ.. t ō Ṇ ,..,

5 MICROUTRIET FORMS I DUY LADSCAPE : 139 slightly mre in the subsil f bth f the stabilized dunes. Free Fe cntent varied frm t per cent and was cnspicuusly mre in the dune and intcrdunal sils f higher rainfall zne (0.230 t 0.406%) and shwed increasing trend 'with the depth. The exchangeable Fe varied frm 2.19 t 8.13 ppm in all the sils except the interdunaj Palsana which cntained cnspicuusly higher amunt (7.1 t 22.5 ppm). The DTPA- Fe varied frm 3.68 t ppm and was highest in dune sils f lw rainfall zne fllwed by Palsana. dunes and interdunes. When viewed frm the critical limit f 2 ppm exchangeablejdtpa extractable all the sils appeared well prvided with this nutrient. A cmparisn f theses sandy sils with medium t fine textured sils f arid Rajasthan (Jshi et al, 1981 a) revealed that thugh the HCl sluble Fe was in cmparable ranges, the exchangeable and free irn were less and DTPA extract:lble frm was much higher. The HCI sluble and free Mn cntents varied frm 101 t and 21.2 t ppm, respectively. Bth the frms were mre in higher rainfall zne dune and interdunal sils shwed increasing trend with depth. The increase in free Mn was greater than in the HCI sluble frm. In lwer rainfall zne, interdunal and sandy plain sils in cmparisn t their respective dune sils, cntained mrc f HCI sluble and free Mn. The reducible and active Mn varied frm 2 t and 2.6 t 92.1 ppm, respectively. The lwer rainfall zne sils cntained less f reducible (2.0 t 26.2 ppm) and active (2.6 t 26.9 ppm) manganese. Interdunal sils appeared t cntain slightly higher amunts than their assciated dunes but the sandy plains were generally lw in these frms. In higher rainfall zne the interdunal sils cntained higher amunts shwing increasing trend with the depth. In different sils exchangeable and DTPA-Mn varied frm 0.43 t 3.28 and 1.11 t ppm, respectively. Thugh there was nt much difference in the exch-mn cntent the DTPA-Mn cntent was lw in the dune sil f lw rainfall. In bth the rainfall znes interdunal sils cntained slightly higher amunts f DTPA-Mn than their respective dunes. An appraisal f these' sils fr Mn availability with the critical limit f 15 ppm reducible Mn revealed that the dune and sandy plain sils f lw rainfall were deficient. All the sils studied were deficient when viewed frm the critical limit f 5 ppm exchangeable Mn. With the critical limit f 5 ppm DTPA Mn the interdunal sils f the bth the rainfall znes appeared marginal but the dune sils were deficient. fn the studied sils, the cntents f all the frms f manganese were Jess than in the medium and fine textured sils (Jshi et al., 1981 a). DISTRIBUTIO OF FORMS OF Zn. AD Cu The HCI sluble Zn cntent f different sils varied frm 11 t 29 ppm. Dune sils f lw rainfall zne cntained less HCI sluble Zn. Interdunal and sandy' plains sils f bth the rainfall znes

6 ]40 : D. C. JOSHI AD R. P. DHIR were slightly higher than their respective dune sils. The exchangeable and DTPA- Zn cntents f these sils varied frm 0.28 t 1.60 ppm and 0.27 t 1.65 ppm, respectively. The exchangeable Zn cntent f the dune sils f lw rainfall zne was slightly lwer than the dune sils f higher rainfall. In bth the rainfall znes the interdunal sils cntained slightly less exchangeable Zn than the dune sils. The DTPA-Zn was n the cntrary higher in dune sils f lw rainfall zne and interdunal and sandy plain sils cntained slightly lwer amunts than their respective dune sils. A cmparisn f the cntent f different frms f Zn with the medium and fine textured sils indicated that the HCI sluble Zn was lwer whereas DTPA and exchangeable Zn were in cmparable amunts (Jshi et 01., 1981 b). When viewed frm the critical limit f 0.8 t ].0 ppm 1T'0st f the sils appeared marginal t sufficient. The HCI sluble Cll cntent f different sils varied frm 4.5 t 18.7 ppm being lw in dune sils f lw rainfall area. The interdunal sils in bth the rainfall znes and sandy plains in lw rainfall cntained smewhat mre f HCI sluble <;:11 than their assciated dune sils. The exchangeable and DTPA-Cu cntents f these sils varied frm 0.16 t 0.41 and 0.12 t 0.56 ppm, respectively. There was nt much difference in the exchangeable Cu cntent f dune sils f bth the rainfall znes and interdunes f higher rainfall znes. But the interdune and sandy plain f lw rainfall zne cntained slightly higher amunts. DTPA-Cu cntent varied frm 0.12 t 0.36 ppm in different hrizns f the dunes f bth the rainfall znes and in sandy plain prfiles. The interdune f bth the rainfall zne cntained slightly higher amunts. When examined with the critical limit f 0.2 ppm DTPA-Cu nly barchan dune sil appeared lw where as ther sils were marginal t sufficient. A cmparisn with medium t fine textured sils revealed that the studied sils generally cntained less amunts f all the frms. The studies revealed that higher reducible and active Mn, DTPA sluble Mn and Zn cntent in the sils f higher rainfall appeared related with their lw ph and CaC0 3 values and sme what higher rganic carbn cntent. These bservatins are in accrdance with the earlier bservatins (Jshi et al., 1981 b). Similarly, higher cntent f the HCI sluble Mn, Zn and Cu and f free Fe and Mn cntent in the sils f higher rainfall zne and their increase with depth is perhaps related with their increased weathering and ill uvial activities. Hwever, ther frms f irn and zinc cntent did nt appear t be related with such activities.. These prcesses were mre prnunced in the interdunal than in the' dune sils. ACKOWLEDGEMETS The authrs are grateful t Dr. H. S. Mann, Directr, and Dr. K. A. Shankarnarayan, Head, Divisin f Basic Resurces Survey, fr facilities prvided.

7 MICROUTRIET FORMS I DUY LADSCAPES: 141 REFERECES Dhir, R. P Western Rajasthan Sils : Their characteristics and prperties. J n "Desertificatin and its Cntrl", ICAR, ew Delhi, pp, Jac ksn, M... L 1958 Sil Chemical Analysis. Prentice Hall f India Ltd. ew Delhi. Jshi, D. C., Dhir R. P. and Gupta, B. S a. A study n the frms f irn and manganese in sme sils f arid Rajasthan. J. Indian Sc. Sil Sci. 29 (4) : Jshi, D. C., Dhir R. P. and Gupta, B. S b. The distributin f different frms f cpper and zinc in sme sils f arid Rajasthan J. Indian Sc. Sil Sci. (In press). Krishnan, A. K., Bhatta, P.. and Rakhecha, P A sil misture regime and micrclimatlgical study ver sand dunes in western Rajasthan. Ann. Arid Zne 5 (I) : 1-9. Lindsay, W. L. and rvell, W. A Develpment f a DTP A sil test fr zinc, irn, manganese and cpper. Sil Sci. Sc. Ame. J. 42 : Mehra, O. P. and Jacksn, M. L Irn xide remval frm sils and clays by a dithinite- Citrate system buffered with saiuffi carbnate. ati. cnf. clays and.hay minerals Muthana, K. D Imprved techniques fr tree plantatin in the arid zne. CAZRI Technical Bulletin.2. Piper, C. S Sil and Plant Analysis. Adelaide, Australia. Saxena, S. K. and Singh, S Sme bservatins n the sand dunes and vegetatin f Bikaner district in W. Rajasthan. Ann. Arid Zne 15 (4) : Sen, A. K Landuse classificatin system in Indian arid zne. CAZRI Mngraph.9.