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Monthly communications by the International Potash Institute, Berne (Switzedand) Subject 4 Soil Science June 1972 50th suite

Potassium Fixation in Soils of

0. P.Verma and G. P.Verma Department of Soil Science and Agricultural Chemistry, J. N. Krishi Vishwa Vidyalaya, , M. P. () From: Bulletin of the Indian Society of Soil Science, No.8, 1970 (India)

Abstract Soils from twentyone districts, representing all the soil types of Madhya Pradesh, were studied for the fixation of applied potassium. The K-fixing capacity of various soil samples varied from zero in soil samples from Tikamgarh, Jabalpur, and Shahdol districtsto 2,95 m.e. K/1 Og soil in asamplefrom Jhabua district. On the basis of soil groups, deep black soils showed maximum average K-fixation and alluvial soils the least. The correlation coefficient value for K-fixation vs pH was positive and signifi- cant in red and yellow and medium black soils. This value between K-fixation and CaCOa content was positive and significant for red and yellow and shallow black soils. A significant and negative relationship was found between potassium fixation and organic carbon contents of red and yellow soils.

Introduction The present unbalanced use of fertilizers in our country has the danger of depleting the available potassium content of the soil to such a low level that response to usual doses of potassium may not be obtained due to fixation. Moreover, fixation of potas- sium regulates not only the supply of soil K for plants but also protects it against leaching. No information about this phenomenon in M. P. soils is available. Hence, present study was carried out to see the extent of K-fixation after it is applied to the soil and how it is influenced by pH, organic matterand CaCOs content of the soil.

Experimental

Surface (0-15 cm) soil samples were taken from each of the 21 districts of M. P., so as to include all the soil types of the State. Potassium fixation was found by adding potassium as KCI solution to each soil sample at 5 m.e. K/1 00 g soil. Then the samples were kept at room temperature-for 3 days after which potassium was extracted with normal neutral ammonium acetate solution and estimated by using a flame photometer. The potassium not extractable by neutral normal ammonium acetate was termed as fixed.

1 Table 1. Potassium fixation and other soil properties

Soil group pH CaCO. Org. carbon K-fixation (m.e./ O0 g) (m.e./1 00 g) Range Average District Soil group Alluvial soils 7,5 44 128 0,2-1,2 0,5 0,5 Morena 8,0 62 188 0,1-0,6 0,4 Deep black soils Narsingpur 7,1 97 136 0,6-1,5 1,1 1,1 Hoshangabad 7,6 80 122 0,8-1,5 1,1 Shallow black soils Chhindwara 6,9 90 317 0,1-1,4 0,6 0,7 Seoni 6,6 65 386 0,4-1,4 0,8 Mixed red and black soils Rewa 6,8 78 206 0,0-1,4 0,5 0,6 Satna 7,0 108 247 0,7-1,8 1,2 Shivpuri 7,6 102 270 0,0-0,8 0,6 Tikamgarh 6,8 77 165 0,0-0,7 0,3 Medium black soils Saugar 7,4 73 263 0,8-1,7 1,2 0,7 Sidhi 7,5 39 202 0,1-2,0 0,8 Jabalpur 7,0 41 445 0,0-1,1 0,5 Damoh 6,8 111 182 0,0-0,3 0,1 Jhabua 7,6 94 300 0,3-3,0 0,8 Shajapur 7,9 249 294 0,1-1,5 0,5 Red and yellow soils Durg 6,9 96 315 0,1-0,5 0,2 0,8 Raigarh 6,6 90 211 1,1-1,7 1,4 Raipur 6,7 45 246 0,3-1,3 O,8 Sarguja 6,5 32 179 0,3-0,6 0,4 Shahdal 6,5 66 166 0,0-2,7 0,9

Results and discussion The range and average values of potassium fixation in different soil groups are giv- en in table 1. The maximum variation is present in soils of Shahdal and Jhabua dis- tricts and minimum in the districts of Damoh and Sarguja. The average value of K-fix- ation for the districts of Narsingpur, Hoshangabad, Satna, Saugar and Raigarh is be- tween 1,1 to 1,4 m.e./ 00 g soil whereas the same value for Gwalior, Chhindwara, Rewa, Shivpuri, Sidhi, Jabalpur, Damoh, Jhabua, Shajapur, Raipur and Shahdol lies between 0,6 to 0,9 m.e. For the r6maining districts of Morena, Tikamgarh, Damoh, Durg and Sarguja, K-fixation is between 0,1 and 0,4 m.e. K/i 00 g soil. On the basis of soil groups, maximum K-fixation was shown by deep black soil and minimum by al- luvial soil. Soil groups can be arranged as follows on the basis of their K-fixing capac- ity: Deep Black > Red and Yellow > Medium black > Shallow Black > Mixed Red and Black > Alluvial.

Correlation studies The correlation coefficient values of potassium fixation with other soil properties are given in table 2.

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Monthly communications by the International Potash Institute: Berne (Switzerland)

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Table 2. Correlation coefficient values of K-fixation in different soils

Soil group Potassium fixation vs pH CaCO , Org. carbon

Alluvial soils -0,276 -0,546 -0,515 Deep black soils +0.161 -0,061 -0,014 Red and yellow soils +0,96* +0,713* -0,461- Medium black soils +0,706 -0,214 -0,053 Mixed red and black soils -0,0211 +0.175 +0,293 Shallow black soils +0,385 +0,532" -0,063

Significant at 1% level; ' Significant at 5% level.

Potassium fixation vs. pH:The 'r' values obtained were both positive and negative but only positive values were significant in red and yellow and medium black soils. Therefore, in red and yellow and medium black soils, fixation of applied potassium in- creases as the pH increases. According to Joffe and Levine (1947), an excess of cal- cium ions which increases the pH values, decreases the amount of exchangeable K due to its (K) fixation into crystal lattice. Thus, in medium black soils having a pH range of 6,8 to 7,9, a positive relation is expected. In red and yellow soils having a pH range of 6,5 to 6,9, H30+ will be the dominating ion on exchange complex and these will decrease with an increase in pH. Since HaO+ behaves like NH+4,and K+ its blocking effect oh K-fixation will mean lower K-fixation at lower pH and greater K-fixation at higher pH. Thus in red and yellow soils, a positive correlation for pH vs. K-fixation is expected. Potassium fixation vs CaC03: In red and yellow and shallow black soils, the corre- lation coefficient was positive and significant indicating that in these soils, higher the CaCO., higher will be K-fixation. Powel/and Hutcheson (1965) also reported similar results. Effect of organic carbon on potassium fixation: From table 2 it is seen that in red and yellow soils, organic carbon has significantly decreased the K-fixation which is very obvious as it is known that organic matter has got blocking effect on potassium fixation. In alluvial soils the negative 'r' value just failed to be significant at 5 per cent level which may be due to less number of soil samples.

Acknowledgement

Authors express their thanks to Dr. D. P. Motiramani, former Head of the Department, for his valuable suggestions.

Bibliography

1. Joffe J.S., Levine A.K.: Soil Sci. 63, 241 (1947). 2. Powell A.J.,Jr., Hutcheson T.B., Jr.: Proc. Soil Sci. Soc. Am. 29, 76 (1965). 3