Journal of Environmental Biology

Labile and stabilised fractions of soil organic carbon in some

intensively cultivated alluvial soils

B.C. Verma^1*, S.P. Datta², R.K. Rattan² and A.K. Singh³

¹Division of NRM, ICAR Research Complex for NEH Region, Umiam-793103, India

²Division of Soil Science and Agricultural Chemistry, Indian Agricultural Research Institute, New Delhi- 110 012, India

³Rajmata Vijayaraje Scindia Krishi Vishwa Vidyalaya, Gwalior-474 002, India

*Corresponding Author email : bibhash.ssac@gmail.com

Publication Data

Paper received:

23 August 2012

Revised received:

09 January 2013

Accepted:

01 February 2013

Abstract

The present investigation was undertaken in view of the limited information on the relative proportion of labile and stabilized fractions of soil organic carbon (SOC) in intensively cultivated lands, particularly under tropics. The specific objectives were i) to study the comparative recovery of SOC by different methods of labile carbon estimation under intensively cultivated lands and ii) to evaluate the impact of agricultural practices on carbon management index. For this purpose, in all, 105 surface soil samples were collected from intensively cultivated tube well and sewage irrigated agricultural lands. These samples were analysed for total as well as labile pools of SOC. Results indicated that Walkley and Black, KMnO₄-oxidizable and microbial biomass carbon constituted the total SOC to the extent of 10.2 to 47.4, 1.66 to 23.2 and 0.30 to 5.49%, respectively with the corresponding mean values of 26.2, 9.16 and 2.15%. Lability of SOC was considerably higher in sewage irrigated soils than tube well irrigated soils under intensive cropping. Under soybean-wheat, the higher values of carbon management index (CMI) (279 and 286) were associated with the treatments where entire amount of nitrogen was supplied through FYM. Similar results were obtained under rice-wheat, whereas in case of maize-wheat the highest value of CMI was recorded under treatment receiving NPK through chemical fertilizer along with green manure. There was also a significant improvement in CMI under integrated (chemical fertilizer + organics) and chemical fertilizer-treated plots. The values of CMI ranged from 220 to 272 under cultivated lands receiving irrigation through sewage and industrial effluents.

Key words

Carbon management index, Intensively cultivated lands, Soil organic carbon, Total and labile pools

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