Studies on the forms of potassium and potassium fixing capacity in some arid soils of Jodhpur region

Transcription

1 _._-~ Annals of Arid Zone-17 (3), , 1978 Studies on the forms of potassium and potassium fixing capacity in some arid soils of Jodhpur region D.C. JOSHI, * S.N. JOHARI AND V.C. SHARMA Soil Survey Office, D.P.A.P., Jodhpur (Received on ) ABSTRACT Studies on the forms of potassium and potassium fixing capacity have been carried out in nine profiles of arid region. HCI so!uble, water soluble and exchangeable potassiam were low and N HNOs soluble and fixed potassium were in comparable amounts with that in semi-arid and sub-humid soils. Significant correlation of organic carbon, CaCOs, clay contents and CEC of soils with forms and fixing capacity of soils indicated their impact on relative accumulation of different forms of potassium and their distribution in profiles. Potassium fixing capacity of arid soils ranged from 0.3 to 1.9 m. eq./ioo gm soils. Low fixing capacity was related with the higher potassium saturation of these soils. INTRODUCTION Equilibrium between different forms of potassium and their distribution in profile are governed by soil properties and agroclimatic conditions. Among the different forms, water soluble and exchangeable, and to some extent fixed potassium are related with the availability of potassium to plants. Very little information is available on the status of the forms of potassium and potassium fixing capacity of soils in arid region (Pareek et al., 1972). Therefore the present studies have been taken up to know the status of forms of potassium, potassium fixing capacity and their relationship with soil characteristics in some arid soils of Jodhpur region. MATERIAL AND METHODS Nine profiles from different sites in Bilara, Osian and Jodhpur area representing aeolian, alluvial and plateau soil groups were examined and Prellent addres;:-cemral Arid Zone Research Institute, Jodhpur.

2 274 : D.C. JOSHI et af. sampled. Soils were analysed for ph, EC, Organic carhon, mechanical separates, CaC0 3 and cation exchange capacity by standard methods. Water soluble potassium was extracted by leaching the soil with neutral IN ammonium acetate and HCI soluble potassium by A. E. A. provisional method (Piper, 1950). N HN0 3 soluble potassium was determined by boiling the soil in 1:10 soil to acid ratio for ten minutes (Jackson, 1958). Potassium in all these extracts was determined by Lang's flame photometer. Non-exchangeable potassium was calculated by the difference of exchangeable + water soluble potassium from N HN0 3 soluble potassium. Potassium fixing capacity of soil with and without CaC0 3 and organic matter was determined by the method of Yolk as described by Jackson (1958). RESULTS AND DISCUSSION Data on physicochemical properties are reported in Table 1. Soils are low in organic carbon and normal to slightly alkaline. There is a vide variation in CaC0 3 content (1 to 11.2 per ceflt). Clay content of the soils ranged between 7 to 13 per cent except the Borunda-1 profile which contains up to 26 per cent. Different forms of potassium and potassium fixing capacity are reported as m. eq. per 100 gm of soil (Table 2). HCI soluble potassium in different profiles ranged from 2 to 7 m. eq. per 100 gm soil. Aeolian soils of Gangana, Salwa Kalan, Tinwari-1 and plateau soils of Balarava showed lower ranges (1.7 to 3.8 m. eq.) as compared to other profiles which contained up to 7 m. eq. potassium. HCI soluble potassium in these soils was low when compared with that of Punjab (Kanwar and Grewal, 1966) and Maharashtra (Kadrekar and Kibe, 1972). Significant correlation of HCI soluble potassium with clay content (r=0.585) and CEC (r=0.445) of soils suggested that HCI solubilized the weathered potassium associated with silicate minerals. PotasFium soluble in N HN0 3 was less than 1 m. eq. ill salwa Kalan, Borunda-2 and Tinwari-1 profiles, whereas it ranged between 1 to 2 m. eq. per 100 gm soils in other profiles. Fixed potassium content in these soils varied from 0.6 to 1.6 m. eq. per 100 gm soil and was slightly higher when compared with other soils of Rajasthan (Dhawan et af.) 1968; Chaudhary and Sharma, 1971). Non significant correlation of clay and significant correlation of CEC with N HN0 3 soluble (r=0.814) and fixed potassium (r=0.816) suggested that fixed potassium was related with the CEC in the range of 2 to 13m. eq. per 100 gm of the soils under study. Kanwar and Grewal (1966) also reported similar observations for Punjab soils. N HN0 3 soluble potassium was si6nifica-

3 SOIL POTASSIUM IN JODHPUR REGION 275 Table 1. Physicochemical characteristics of the soils Depth ph CaCo a Org. Silt Clay CEC (em) (%), Carbon I%J <%1 (%) (Meq/IOOg) Gangana-Alluvial Salwa Kalan-Aeolian Borundn 1 Alluvial ' Borunda 2 Plateau Borunda 3-Aeolian ,0 Manak Lav-Aeolian

4 276 D.C. JOSHI et a/. Depth ph CaC0 3 Org. Silt Clay erc (cm) (%) Carbon <%) <%l (%> (Meq/l00g) Tinwari 2-Plateau ' Tinwari I-Aeolian Balarawa-Plateau ntly related with organic carbon content of soil (r=0.691). Per..:ent potassium saturation in soils under study ranged between 4-40 per cent. Borunda-3 and Tinwari-2 profile showed higher ranges (9-40 per cent) as compared to other profiles. These soils may not fix potassium when compared with the observation of Chaminade (1936) who reported that soil havjng degree of potassium saturation values of more than 4.5 fixed, little or no potassium. There was not much difference in the water soluble potassium content of soils which ranged from 0.03 to 0.11 m. eq. per 100 gm soil. This form of potassium was higher in surface than in the subsoil. Gangana, Borunda-l and Tinwari-2 profiles characterized by higher clay content also contained higher amounts of exchangeable potassium (0.46 to 0.82 m. eq. per 100 gm of soil), whereas other profiles showed lower ranges (0.10 to 0.82 m. eq. per 100 gm of soil). These amounts were slightly lower than those reported by Dhawan et al. (1968) and Bhatnagar et a/. (1973) for semi arid and sub humid region soils. There was significant correlation between water soluble potassium and CaC0 3 (r=0.461) and exchangeable potassium and organic carbon (r=0.679) contents of the soils. Water soluble and exchangeable pcta:ssium cont'fibuted 5 to 16 per cent of CEC and were grouped as medium to low in available potassium content (Muhr et at., 1963).

5 Table 2. Different forms of potass Different forms of potassium (m. eg. Depth HCI N HN0 3 Fixed Exchangeable (cm) Soluble Soluble Gangana-Alluvial Salwa Kalan-Aeoliar '> ] Brounda I-Alluvial ] Brounda 2-Plateau ] ; Brour da ] ] ] Aeolian ManakJa-Aeolian ] ] ] Tinwari I-Aeolian Tiuwari Pldtea Balara va-pia teau

6

7 SOIL POTASSIUM IN JODHPUR REGION : 277 Significant correlation of HCl soluble potassium with water soluble (r=0.863) and N HN0 3 soluble (r=0.588) forms suggested that these forms, are closely related. Potassium fixing capacity of soils ranged between 0.30 to 2.70 m. eq. per 100 gm soil. Gangana, Manaklav, Tinwari, and Balarava soils showed lower fixing capacity «1 m. eq.). as compared to Salwa Kalan and Borunda soils. Potassium fixing capacity of arid soils was quite low when compared with medium black (2.5 to 15 m. eq.; Bhatnagar et ai, 1973) and Mewar soils (32.6 to 115 mgm; Bishnoi and Khatri, 1974) per 100 gm soil. This low fixing. capacity was probably due to higher potassium saturation of' these soils (Tdble 2). Allaway and Pierre (1939) reported that under certain conditions effect of lime on availability of potash are very drastic. Potassium fixing capacity of soil after treatment with 6 N HCl and H separately (to remove CaC0 3 and organic matter respectively) indicated that there was decrease (Table 2) in potassium fixing capacity of soil due to removal of CaC0 3 and organic matter in salwa Kalan and Borunda profiles whereas in Manaklav, Balarava and Tinwari profiles slight increase was observed. Such differential trends could be attributed to the potassium saturation of soils. Similar results have also been reported by Chaminaae (1936) Potassium fixing capacity of HCI treated soil was negatively related with CEC (r=0.463). REFERENCES Allaway, H. and Pierre, W. H Availability, fixation and liberation of potassium in high lime soils. Jour. ArneI'. Soc. Agron. 31: Bishnoi, S. R. and Khatri, P. B Potassium fixation in Mewar soils. J. Indian Soc. Soil Sci. 22: Bhatnagar, R. K., Nathani, G. P., Chouhan, S. S. and Seth, S. P Potassium fractions and fixing capacity of medium black soils of Rajasthan. J. Indian Soc. Soil Sci. 21 : Chaminade, R La retrogradation du potassium daus les sols. Ann. Agron. N. S., 6: (Cf. soil plant relationship by C. A. Black. John Willey and Sons, Inc. N. Y.). Choudhary, J. S. and Sharma, D. L Studies on the forms of potassium in relation of geology and physiography of southern Rajasthan. Raj. Jour. Agric. Sci. 2:

8 278 : D.C. JOSHI et al. Dhawan, S., Pareek, B. L. and Mathur, C. M Studies on the forms of potassium in soils of Rajasthan. J. Indian Soc. Soil Sci. 16: Jackson, M. L Soil Chemical Analysis. Constable and Co. London. Kadrekar, S. B. and Kibe, M. M Soil potassium forms in relation to agroclimatic conditions in Maharashtra. J. Indian Soc. Soil Sci. 20: , Kanwar, J. S. and Grewal, J. S Relationship between forms of potassium and particle size. J. Indian Soc. Soil Sci. 14: Muhr, G. R., Datta, N. P., Shankar subramoney, H. Leley V. K. and Donahue, R. L Soil Testing in India. USAID, India. Pareek, B. L., Seth, S. P. and Joshi, D. C Potassium status and its response to major crops in Rajasthan. Potash New letter. V II: Piper, e.s Soil and plant analysis. Adelaide, Australia. Piper, C.S Soil and plant analysis. Adelaide, Australia.