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Changes in soil carbon stocks under different agricultural management practices in North Sri Lanka

Authors:

RR Ratnayake ,

LK
About RR
Institute of Fundamental Studies, Hantana Road, Kandy.
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T Kugendren,

LK
About T

Department of Agricultural Chemistry, Faculty of Agriculture, University of Jaffna, Kilinochchi.

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N Gnanavelrajah

LK
About N

Department of Agricultural Chemistry, Faculty of Agriculture, University of Jaffna, Kilinochchi.

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Abstract

There is great potential of storing and improving carbon in tropical agricultural soils by applying ecologically sound management practices. In this study, soil carbon fractions and stocks under different agricultural management practices were studied in North Sri Lanka. Five land use types, namely, annual crop organic fertilizer only (A-OF), annual crop inorganic fertilizer only (A-IF), annual crop organic + inorganic fertilizer (A-O/IF), perennial crops (PC) and a home garden (HG), which use different tillage practices and fertilizer applications were selected. A home garden abandoned for 20 years (AHG) was included to study no tilled conditions. From the five land use types A-OF showed the highest soil organic carbon (SOC) fractions probably as a result of continuous supply of organic fertilizer for years. Conversely a lower SOC and other labile fractions were observed in A-IF probably due to greater decomposition of native soil organic matter under mineral fertilizer. Microbial biomass carbon (MBC) was significantly different among the treatments with the highest (631 mg/kg) in A-OF. AHG having the highest litter fall with zero tillage maintained the highest SOC content (68 %). Comparatively high water soluble C content (0.055/ 0.57 mg/kg) in both home gardens (HG/ AHG) and PC (0.055 mg/kg) could be possibly due to fresh residues returning to the soil whereas no residues return in annual crop sites. The potential stable carbon stock was the highest in AHG (15.40 t/ha) followed by A-OF (11.17 t/ha) compared to the other agricultural land uses. Active C was the highest in AHG (4.34 t/ha) followed by 3.98 t/ha in HG. A-IF recorded the lowest amount of active C (1.73 t/ha). Soil C stocks of annual crops can be improved compared to all other perennial land uses by using organic fertilizer application. Inorganic fertilizers in annual crops improve soil carbon storage only when combined with organic fertilizers.

DOI: http://dx.doi.org/10.4038/jnsfsr.v42i1.6679

J.Natn.Sci.Foundation Sri Lanka 2014 42 (1): 37-44

How to Cite: Ratnayake, R., Kugendren, T. and Gnanavelrajah, N., 2014. Changes in soil carbon stocks under different agricultural management practices in North Sri Lanka. Journal of the National Science Foundation of Sri Lanka, 42(1), pp.37–44. DOI: http://doi.org/10.4038/jnsfsr.v42i1.6679
Published on 11 Mar 2014.
Peer Reviewed

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