Assessment of Organic Carbon Status in Indian Soils - Soil Carbon: Science, Management and Policy for Multiple Benefits - page 328

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Assessment of Organic Carbon
Status in Indian Soils

Tapas Bhattacharyya *

Abstract
Soil organic carbon (SOC) content in Indian soils has been reported as low, which is in tune with the
fact that nearly 60% of the area in India represents the typical tropical climate, which does not permit
SOC accumulation. Recent evaluation with the help of more soil and site data, model approaches and
long-term fertilizer experiments (LTFEs) show an increasing trend of SOC, as detailed in this chapter
through different case studies in two important food growing zones of India, namely the Indo-Gangetic
Plains (IGP) and the black soil region (BSR). The study shows the evaluation of Century, RothC and
InfoCrop models in LTFEs with contrasting bioclimate in the IGP and the BSR. The Century model
experience necessitates the modification of crop information to suit the tropical conditions found in
India. The RothC output has been found to be useful to arrive at the threshold limit of the mean annual
rainfall as an indicator of organic carbon storage in soil. The InfoCrop cotton model in the BSR indi-
cated that the interaction of increased temperature and CO 2 concentration had a compensatory effect
on crop yield. A methane emission study on Indian agricultural soils has been computed as
2.54 Tg C-CH 4 year - 1 and constitutes 0.23% of global warming. However, although an increase of SOC
has been found in IGP and BSR soils, even in arid and semi-arid environments, the status of soil inor-
ganic carbon will require attention by planners and resource managers in view of soil degradation.

Introduction

and thus maintaining its health in order to
sustain crop productivity, has been well
known since the dawn of human civiliza-
tion. Important factors controlling SOC
status include climate (especially rainfall
and temperature), hydrology, parent material,
soil fertility, biological activity, vegetation and
land use. SOC is sensitive to human activ-
ities such as deforestation, biomass burning,
land-use changes and environmental pollu-
tion. It is estimated that land-use change
results in the transfer of 1-2 Pg C year - 1 from

The restoration of soil health through soil
organic carbon (SOC) management is a major
concern for tropical soils. Barring its im-
portance for sustainable crop production,
the accelerated decomposition of SOC due
to agriculture, resulting in loss of carbon to the
atmosphere and its contribution to the green-
house effect, is a serious global problem.
The contribution of SOC for improving soil
physical, chemical and biological properties,