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Surface Soil and Subsoil Acidity in Natural and Managed Land-Use Systems in the Humid Tropics of Peninsular India


Affiliations
1 Regional Centre, ICAR-National Bureau of Soil Survey and Land Use Planning, Hebbal, Bengaluru 560 024, India
2 ICAR-Central Plantation Crops Research Institute, Kasaragod 671 124, India
3 ICAR-Indian Institute of Spices Research, Kozhikode 673 012, India
4 Rubber Research Institute of India, Kottayam 686 009, India
5 Coffee Research Institute, Chikmagalur 577 117, India
 

Natural forests and managed plantations constitute the largest land-use systems in the humid tropics of southwestern parts of Peninsular India comprising the Western Ghats and coastal plain. Soils therein are naturally acidic and the acidity is enhanced in managed land-use systems through inputs of chemical fertilizers. Plant nutrient deficiencies and mineral toxicities constrain crop production in acid soils. Surface soil and subsoil acidity in forest, coffee, rubber and coconut land-use systems was evaluated. The spatial pattern of surface soil and subsoil acidity pointed to low intensity of acidification in Malnad region of Karnataka, moderate acidity in northern Kerala and strong acidity in southern Kerala. Among the land-use systems studied, soils under natural forests and coffee plantations were only slightly acidic in surface soil and subsoil, whereas rubber- and coconut-growing soils were strongly acidic. Both natural and managed land-use systems, however, had strongly acid reaction in surface soil and subsoil in southern Kerala. Biomass production and crop yield are constrained in strongly acid soil by toxic levels of aluminium (Al) on soil exchange complex (>0.5 cmol (+) kg–1 soil) and depletion of basic cations of calcium, magnesium and potassium (base saturation less than 50% or Al saturation more than 50%). Surface soil acidity can be ameliorated by incorporating liming materials into surface soils. In case of subsoil acidity gypsum too should be incorporated. Under humid climate partial solubility of gypsum permits movement of calcium into the subsoil layers, wherein calcium replaces the aluminium on exchange complex and sulphate radical precipitates the aluminium by formation of aluminium sulphate.

Keywords

Base Saturation, Humid Tropics, Land-Use Systems, Surface Soil and Subsoil Acidity.
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  • Surface Soil and Subsoil Acidity in Natural and Managed Land-Use Systems in the Humid Tropics of Peninsular India

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Authors

K. M. Nair
Regional Centre, ICAR-National Bureau of Soil Survey and Land Use Planning, Hebbal, Bengaluru 560 024, India
K. S. Anil Kumar
Regional Centre, ICAR-National Bureau of Soil Survey and Land Use Planning, Hebbal, Bengaluru 560 024, India
M. Lalitha
Regional Centre, ICAR-National Bureau of Soil Survey and Land Use Planning, Hebbal, Bengaluru 560 024, India
Shivanand
Regional Centre, ICAR-National Bureau of Soil Survey and Land Use Planning, Hebbal, Bengaluru 560 024, India
S. C. Ramesh Kumar
Regional Centre, ICAR-National Bureau of Soil Survey and Land Use Planning, Hebbal, Bengaluru 560 024, India
S. Srinivas
Regional Centre, ICAR-National Bureau of Soil Survey and Land Use Planning, Hebbal, Bengaluru 560 024, India
Arti Koyal
Regional Centre, ICAR-National Bureau of Soil Survey and Land Use Planning, Hebbal, Bengaluru 560 024, India
S. Parvathy
Regional Centre, ICAR-National Bureau of Soil Survey and Land Use Planning, Hebbal, Bengaluru 560 024, India
K. Sujatha
Regional Centre, ICAR-National Bureau of Soil Survey and Land Use Planning, Hebbal, Bengaluru 560 024, India
C. Thamban
ICAR-Central Plantation Crops Research Institute, Kasaragod 671 124, India
Jeena Mathew
ICAR-Central Plantation Crops Research Institute, Kasaragod 671 124, India
K. P. Chandran
ICAR-Central Plantation Crops Research Institute, Kasaragod 671 124, India
Abdul Haris
ICAR-Central Plantation Crops Research Institute, Kasaragod 671 124, India
V. Krishnakumar
ICAR-Central Plantation Crops Research Institute, Kasaragod 671 124, India
V. Srinivasan
ICAR-Indian Institute of Spices Research, Kozhikode 673 012, India
Jessy
Rubber Research Institute of India, Kottayam 686 009, India
James Jacob
Rubber Research Institute of India, Kottayam 686 009, India
J. S. Nagaraj
Coffee Research Institute, Chikmagalur 577 117, India
Maria Violet D’Souza
Coffee Research Institute, Chikmagalur 577 117, India
Y. Raghuramulu
Coffee Research Institute, Chikmagalur 577 117, India
R. Hegde
Regional Centre, ICAR-National Bureau of Soil Survey and Land Use Planning, Hebbal, Bengaluru 560 024, India
S. K. Singh
Regional Centre, ICAR-National Bureau of Soil Survey and Land Use Planning, Hebbal, Bengaluru 560 024, India

Abstract


Natural forests and managed plantations constitute the largest land-use systems in the humid tropics of southwestern parts of Peninsular India comprising the Western Ghats and coastal plain. Soils therein are naturally acidic and the acidity is enhanced in managed land-use systems through inputs of chemical fertilizers. Plant nutrient deficiencies and mineral toxicities constrain crop production in acid soils. Surface soil and subsoil acidity in forest, coffee, rubber and coconut land-use systems was evaluated. The spatial pattern of surface soil and subsoil acidity pointed to low intensity of acidification in Malnad region of Karnataka, moderate acidity in northern Kerala and strong acidity in southern Kerala. Among the land-use systems studied, soils under natural forests and coffee plantations were only slightly acidic in surface soil and subsoil, whereas rubber- and coconut-growing soils were strongly acidic. Both natural and managed land-use systems, however, had strongly acid reaction in surface soil and subsoil in southern Kerala. Biomass production and crop yield are constrained in strongly acid soil by toxic levels of aluminium (Al) on soil exchange complex (>0.5 cmol (+) kg–1 soil) and depletion of basic cations of calcium, magnesium and potassium (base saturation less than 50% or Al saturation more than 50%). Surface soil acidity can be ameliorated by incorporating liming materials into surface soils. In case of subsoil acidity gypsum too should be incorporated. Under humid climate partial solubility of gypsum permits movement of calcium into the subsoil layers, wherein calcium replaces the aluminium on exchange complex and sulphate radical precipitates the aluminium by formation of aluminium sulphate.

Keywords


Base Saturation, Humid Tropics, Land-Use Systems, Surface Soil and Subsoil Acidity.

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DOI: https://doi.org/10.18520/cs%2Fv116%2Fi7%2F1201-1211