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Int.J.Curr.Microbiol.App.Sci (2020) 9(10): 1879-1884 International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 9 Number 10 (2020) Journal homepage: http://www.ijcmas.com Original Research Article https://doi.org/10.20546/ijcmas.2020.910.230 Characterization of Soil Acidity under Paddy Land Use Cover of Coastal Karnataka S. M. Jayaprakash*, H. M. Chidanandappa, B. C. Dhananjaya, G. N. Thippeshappa, Y. Vishwanatha Shetty and M. Hanumanthappa Zonal Agricultural & Horticultural Research Station, Brahmavar, UAHS, Shivamogga, India *Corresponding author ABSTRACT Keywords Acidity, Exchangeable, Paddy, Calcium and Magnesium Article Info Accepted: 15 September 2020 Available Online: 10 October 2020 The study was conducted at coastal zone of Karnataka to characterize the acidity of soils and to assess calcium and magnesium status of soils under paddy land is cover. Soil samples were collected at depth of 0-15cm from paddy growing areas of Dakshina Kannada and Udupi districts. The collected soil sample were processed and analyzed to know the physical and chemical properties of soil, the nature of soil acidity and the status of exchangeable calcium and magnesium in soils. The result from the present investigation revealed that active acidity was ranged from 2.19 x 10-6 to 8.9 x 10-5mol H+ L-1, exchangeable acidity was in the range of 0.401 to 5.959 cmol (p +) kg-1 g, pH dependent acidity varied from 3.000 to 49.875 cmol (p +) kg-1 and the total potential acidity which included both exchangeable and pH dependent acidity ranged from 4.98 to 50.818 cmol (p+) kg-1. From the investigation we came to know that more than 99.9 per cent of the total acidity in soils was found to be in the form of potential acidity and out of which nearly 8 per cent was in the form of exchangeable acidity. However, the order of distribution of different forms of acidity was found to be as follows; pH dependent acidity>Exchangeable acidity>Active acidity. Introduction Soil acidity is one of the factors affecting the availability of Ca and Mg in soils. Availability of Ca and Mg in soils decreases with increase in acidity of soil. Because of low status in exchangeable Ca and Mg and other acid related problems, the productivity of acid soil found to be low. The soil which is subjected to heavy rainfall resulting in leaching of nutrients such as potassium, calcium and magnesium and accumulation of oxides of Al and Fe lead to poor soil fertility and low pH. Balasubramanian and Raj (1969) reported that among the different forms of phosphate in laterite soils Fe and Al phosphate occupied major portion than Ca phosphate in those soils. Owing to low availability of Ca and Mg in acid soils due to soil acidity related problems such as leaching loss of bases and high 1879 Int.J.Curr.Microbiol.App.Sci (2020) 9(10): 1879-1884 concentration of exchangeable Al and low CEC, the productivity of acid soil is found to be low (Craswell and Pushparajah, 1989). Similarly, Haynes and Ludecke (1981) reported that both soluble and exchangeable Ca decreased with decreasing soil pH. Further, at low pH, the bioavailability of Ca was retarded by high concentration of Al. Similarly, low CEC and high saturation of Fe and Al in acid soils, magnesium remained in soil solution and subjected for leaching loss (Edmeades et al., 1985; Myers et al., 1988). Therefore, it is understood that in highly weathered soils the availability of Ca and Mg is insufficient for crop production. Hence, it is very much essential to supply Ca and Mg in the form of liming material to overcome the problems of acid soils and also to increase their production potential. assess the physical and chemical properties, distribution of different forms of acidity and exchangeable calcium and magnesium status in soil for this 60 and 100 (Total 160) surface soil samples (0 – 15 cm depth) were collected from soils coming under paddy growing areas of Dakshina Kannada and Udupi districts of coastal Karnataka, respectively. The collected samples were processed in the laboratory and preserved for further analysis (Table 1 and 2). The area of Coastal zone of Karnataka comprised of 1.17 m. ha which covers areas of Uttar Kannada, Udupi and Dakshina Kannada districts. The annual rainfall ranges from 3010.9 to 4694.4 mm, of which 80 per cent is received during the months of May to October. The elevation of land ranges from 300 to 800 meters. The soils are red lateritic and coastal alluvial and belong to Ultisols order. The Major crops grown in this zone are paddy, coconut and areca nut, cashew, pulses, rubber, groundnut and vegetables. Paddy is generally cultivated in three seasons in a year, Karthika or Yenel (May – October), Suggi (October to January) and Kolake (January to April). From the present investigation it was found that sand had a positive correlation with active acidity (r = 0.146) and negative and significantly correlated with silt (r = 0.429**), clay (r = -0.652**), exchangeable acidity (r = -0.224**), pH dependent acidity (r = -0.199*), potential acidity (r = -0.224**), EC (r = -0.214**), organic carbon (r = 0.188*), CEC (r = -0.556**), exchangeable calcium (r = -0.200*) and exchangeable magnesium (r = -0.370**). Materials and Methods The present investigation involved a soil survey to know physical and chemical properties, the nature of soil acidity and the status of exchangeable calcium and magnesium in soils under paddy cover of Coastal Karnataka. As a part of the investigation, a survey was conducted to Results and Discussion Correlation matrix observed between soil physical, chemical properties and forms of acidity in soils paddy cover of Coastal Karnataka Soil physical properties Silt had a positive and significantly correlation with active acidity (r = 0.301**) and positively correlated with exchangeable calcium (r = 0.045) and negatively and significantly correlated with clay (r = 0.406**), exchangeable acidity (r = -0.192*), pH dependent acidity (r = -0.219**), potential acidity (r = -0.237**), organic carbon (r = 0.282**), CEC (r = -0.185*) and negatively correlated with EC (r = -0.106) and exchangeable magnesium (r = -0.031). Clay positively and significantly correlated with exchangeable acidity (r = 0.388**), pH 1880 Int.J.Curr.Microbiol.App.Sci (2020) 9(10): 1879-1884 dependent acidity (r = 0.385**), potential acidity (r = 0.425**), EC (r = 0.305**), organic carbon (r = 0.427**), CEC (r = 0.718**), exchangeable calcium (r = 0.165*) and exchangeable magnesium (r = 0.400**) and negative and significantly correlated with active acidity (r =- 0.400**). Soil chemical properties Active acidity Active acidity had a positive and significantly correlation with exchangeable calcium (r = 0.263**) and positively correlated with exchangeable magnesium (r = 0.044), negative and significantly correlated with exchangeable acidity (r = -0.540**), potential acidity (r = -0.201*), EC (r = -0.315**), organic carbon (r = -0.440**) and CEC (r = 0.471**) and negatively correlated with pH dependent acidity (r = -0.117). Exchangeable acidity Exchangeable acidity had a positive and significant correlation with pH dependent acidity (r = 0.310**), potential acidity (r = 0.459**), organic carbon (r = 0.433**) and CEC (r = 0.724**), positively correlated with EC (r = 0.081), negative and significantly correlated with exchangeable calcium (r = 0.488**) and negatively correlated with exchangeable magnesium (r =- 0.146). Soil reaction (pH) pH dependent acidity had a positive and significantly correlation with potential acidity (r = 0.987**), organic carbon (r = 0.391**), CEC (r = 0.316**), positively correlated EC (r = 0.002), with exchangeable magnesium (r = 0.002) and negatively correlated with exchangeable calcium (r = -0.045). Potential acidity had a positive and significant correlation organic carbon (r = 0.438**) and CEC (r = 0.418**), positively correlated with EC (r = 0.016) and negatively correlated with exchangeable calcium (r = -0.125) and exchangeable magnesium (r = -0.023). Electrical conductivity Electrical conductivity had a positive and significantly correlation with CEC (r = 0.232**) and positively correlated with organic carbon (r = 0.134), exchangeable calcium (r = 0.148) and exchangeable magnesium (r = 0.090). Organic carbon had a positive and significantly correlation with CEC (r = 0.391**), positively correlated with exchangeable magnesium (r = 0.095) and negative and significant correlation with exchangeable calcium (r = -0.186*). CEC had a positive and significant correlation with exchangeable magnesium (r = 0.389**) and positively correlated with exchangeable calcium (r = 0.043). Exchangeable calcium had a positive and significant correlation with exchangeable magnesium (r = 0.205*). The results of above study indicates that Udupi and Dakshina Kannada districts active acidity in the soils of Udupi and Dakshina Kannada districts is ranged from 2.19 x 10-6 to 8.9 x 10-5mol H+ L-1, exchangeable acidity was in the range of 0.401 to 5.959 cmol (p+) kg-1 g, pH dependent acidity varied from 3.000 to 49.875 cmol (p+) kg-1 and the total potential acidity which included both exchangeable and pH dependent acidity ranged from 4.98 to 50.818 cmol (p+) kg-1. Therefore, it was understood that more than 99.9 per cent of the total acidity in soils was found to be in the form of potential acidity and out of which nearly 8 per cent was in the form of exchangeable acidity. 1881 Int.J.Curr.Microbiol.App.Sci (2020) 9(10): 1879-1884 Table.1 Correlation matrix (‘r’ values) recorded between exchangeable calcium and magnesium, soil properties and forms of acidity in soils under paddy cover of Coastal Karnataka Sand Sand Silt Clay AA (pH) EA pH DA PA EC OC CEC Ex. Ca2+ Ex. Mg2+ 1.000 -0.429** -0.652** 0.146 -0.224** -0.199* -0.224** -0.214** -0.188* -0.556** -0.200* -0.370** Silt Clay AA (pH) EA 1.000 -0.406** 1.000 0.301** -0.400** 1.000 -0.192* 0.388** -0.540** 1.000 -0.219** 0.385** -0.117 0.310** -0.237** 0.425** -0.201* 0.459** -0.106 0.305** -0.315** 0.081 -0.282** 0.427** -0.440** 0.433** -0.185* 0.718** -0.471** 0.724** 0.045 0.165* 0.263** -0.488** -0.031 0.400** 0.044 -0.146 (Note:AA: Active Acidity (pH) pH DA: pH Dependant Acidity pH DA PA EC OC CEC Ex. Ca2+ Ex. Mg2+ 1.000 0.987** 0.002 0.391** 0.316** -0.045 0.002 1.000 0.016 0.438** 0.418** -0.125 -0.023 1.000 0.134 0.232** 0.148 0.090 1.000 0.391** -0.186* 0.095 1.000 0.043 0.389** 1.000 0.205* 1.000 EA: Exchangeable Acidity, PA: Potential acidity, EC: Electrical Conductivity, OC: Organic carbon, CEC: Cation Exchange Capacity) Table.2 Exchangeable calcium and magnesium Status (deficient & sufficient) in soils under paddy cover in Coastal Karnataka District Calcium Total no. of samples analysed No. of samples recorded above the critical limit of calcium No. of samples recorded below the critical limit of of calcium Magnesium Total no. of samples analysed. No. of samples recorded above the critical limit of of magnesium No. of samples recorded below the critical limit of magnesium Udupi Dakshina Kannada Total 100 46 (46.0%) 54 (54.0%) 60 20 (33.33%) 40 (66.67%) 160 66 (41.25%) 94 (58.75%) 100 44 (44.0%) 56 (56.0%) 60 22 (36.67%) 38 (63.33%) 160 66 (41.25%) 94 (58.75%) [Note: Critical limits of exch. Ca2+ and Mg2+ in soils are 2.00 and 0.5 meq 100g, respectively. (Fundamentals of Soil Science, Published by ISSS)] 1882 Int.J.Curr.Microbiol.App.Sci (2020) 9(10): 1879-1884 However, the order of distribution of different forms of acidity was found to be as follows; pH dependent acidity > Exchangeable acidity > Active acidity. High potential acidity in soils may be attributed to the soils are dominated with Fe and Al oxides, kaolinite minerals and medium to high in organic matter status. The above materials saturated with H+ and Al3+ ions in exchangeable and non exchangeable forms. Further, it is known that the potential acidity is in a dynamic equilibrium with active acidity in soils as a result the pH of soils was found to be low due to high active acidity in soils (Dolui and Sarkar 2001, Arunima et al., 2012 and Chimdi et al., 2012) In conclusion, The exchangeable Ca status in soils ranged from 0.58 to 3.86 cmol (p+) kg-1 with a mean of 1.88 cmol (p+) kg-1 and exchangeable Mg varied from 0.02 to 2.59 cmol (p+) kg-1 with a mean of 0.54 cmol (p+) kg-1 Further, out of 160 samples analyzed for exchangeable Ca and Mg, 68.75 per cent samples recorded the exchangeable Ca below critical limit (2.0 cmol (p+) kg-1). Similarly, 48.75 per cent samples recorded the exchangeable Mg status below the critical limit of Mg (0.5 cmol (p+) kg-1). Soils were fractionated for different forms of acidity and their distribution in soils whereas follows; Active acidity ranged from 2.19 x 106 to 8.9 x 10-5 mol H+ L-1, exchangeable acidity was in the range of 0.401 to 5.959 cmol (p+) kg-1, pH dependent acidity varied from 3 to 49.875 cmol (p+) kg-1 and total potential acidity which includes exchangeable and pH dependent acidity ranged from 4.98 to 50.818 cmol (p+) kg-1. Therefore, it was noticed that more than 99.9 per cent of the total acidity in soils was found to be in the form of potential acidity and out of which nearly 8 percent was in the form of exchangeable acidity. However, the order of their distribution in soils was found to be as follows; pH dependent acidity > Exchangeable acidity > Active acidity. References Arunima, G., Talukdar, M. C. and Ananta Dutta, 2012, Physico-chemical characteristics of acid soils of Amguri block in Sivasagar district, Assam. In; Compendium of Abstracts, 8th PSILPH, UAS, Bangalore: Pp. 39-40. Balasubramanian, V. and Raj, D., 1969, Study of the forms of soil P in Tamil Nadu. Madras Agric. J., 56: 790-793. Chimdi, A., Gebrekidan, A., Kibret, K. and Tadesse, A., 2012, Effects of Liming on acidity-related chemical properties of soils of different land use systems in Western Oromia, Ethiopia. World J. Agric. Sci., 8(6): 560-567. Craswell, E. T. and Pushparajah, E., 1989, Management of acid soils in the Humid Tropics of Asia. Australian Centre for Int. Agric. Res (ACIAR) Monograph No.13 (mSRAM Monograph No.1), 118 p. Dolui, A. K. and Sarkar, R., 2001, Influence of nature of acidity onlime requirement of two Inceptisol and an Alfisol. J. Indian Soc. Soil Sci., 49: 195-198. Edmeades, D. C., Wheeler, D. M. and Crouchley, G., 1985, Effects of liming on soil magnesium on some soils in New Zealand. Commun. Soil Sci. Plant Anal., 16: 727–739. Haynes, R. J. and Ludecke, T. E., 1981, Effect of lime and phosphorus applications on concentrations of available nutrients and on P, Al and Mn uptake by 2 pasture legumes in an acid soil. Pl. Soil. 62: 117– 128. Myers, J. A., Mclean, E. O. and Bingham, J. M., 1988, Reductions in exchangeable magnesium with liming acid Ohio soils. Soil Sci. Soc. Am. J., 52: 131–136. 1883 Int.J.Curr.Microbiol.App.Sci (2020) 9(10): 1879-1884 How to cite this article: Jayaprakash, S. M., H. M. Chidanandappa, B. C. Dhananjaya, G. N. Thippeshappa, Y. Vishwanatha Shetty and Hanumanthappa, M. 2020. Characterization of Soil Acidity under Paddy Land Use Cover of Coastal Karnataka. Int.J.Curr.Microbiol.App.Sci. 9(10): 1879-1884. doi: https://doi.org/10.20546/ijcmas.2020.910.230 1884