Carbon sequestration in the semi‐arid tropics for improving livelihoods

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  • This article was downloaded by: [UQ Library]On: 24 November 2014, At: 11:01Publisher: RoutledgeInforma Ltd Registered in England and Wales Registered Number: 1072954 Registeredoffice: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK

    International Journal of EnvironmentalStudiesPublication details, including instructions for authors andsubscription information:http://www.tandfonline.com/loi/genv20

    Carbon sequestration in the semiaridtropics for improving livelihoodsS.P. Wani a , K.L. Sahrawat a , T.K. Sreedevi a , T. Bhattacharyya b

    & Ch. Sreenivasa Rao aa International Crops Research Institute for the SemiArid Tropics(ICRISAT) , Patancheru, 502 324, Andhra Pradesh, Indiab National Bureau of Soil Survey and Land Use Planning , Nagpur,440 010, Maharashtra, IndiaPublished online: 17 Dec 2007.

    To cite this article: S.P. Wani , K.L. Sahrawat , T.K. Sreedevi , T. Bhattacharyya & Ch. SreenivasaRao (2007) Carbon sequestration in the semiarid tropics for improving livelihoods, InternationalJournal of Environmental Studies, 64:6, 719-727, DOI: 10.1080/00207230701778262

    To link to this article: http://dx.doi.org/10.1080/00207230701778262

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    http://www.tandfonline.com/page/terms-and-conditionshttp://www.tandfonline.com/page/terms-and-conditions

  • International Journal of Environmental Studies,Vol. 64, No. 6, December 2007, 719727

    International Journal of Environmental StudiesISSN 0020-7233 print: ISSN 1029-0400 online 2007 Taylor & Francis

    http://www.tandf.co.uk/journalsDOI: 10.1080/00207230701778262

    Carbon sequestration in the semi-arid tropics for improving livelihoods

    S.P. WANI*, K.L. SAHRAWAT, T.K. SREEDEVI, T. BHATTACHARYYA AND CH. SREENIVASA RAO

    International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru 502 324,Andhra Pradesh, India, National Bureau of Soil Survey and Land Use Planning, Nagpur 440 010,Maharashtra, IndiaTaylor and FrancisGENV_A_277835.sgm

    (Received 31 October 2007)10.1080/00207230701778262International Journal of Environmental Studies0020-7233 (print)/1029-0400 (online)Original Article2007Taylor & Francis0000000002007Suhas P.WaniS.WANI@cgiar.org

    This paper reviews the research conducted by ICRISAT and its partners on the role of managementsystems on carbon sequestration and crop productivity in the semi-arid regions of India. It is nowestablished that apart from water shortages, the dryland productivity is also constrained by lowfertility mainly caused by the low organic matter status of most soils. Sequestration of atmosphericcarbon dioxide in the soil has the potential to achieve the multiple objectives of improving the soilquality and fertility of the semi-arid tropical soils, increasing crop productivity, improvinglivelihoods and maintaining environmental quality.

    Keywords: Soil quality; Low fertility; Carbon sequestration and soil fertility; Environmental quality; Semi-arid tropical soils; Dryland farming

    Introduction

    In the semi-arid tropical (SAT) regions, farmers suffer from water shortages. In addition,they face low rainwater use efficiency in terms of crop production. This is largely caused byinappropriate soil and water management and soil infertility. These are the major constraintsto agricultural productivity and the reason for the low incomes of farmers. Indeed, mainte-nance of soil fertility in the SAT, a prerequisite for sustainable increase in productivity, is amajor challenge to researchers and farmers alike. Soils in the SAT regions are low in organicmatter and nutrient reserves. Prevailing production systems do not support sufficient inputsof organic matter for the maintenance of soil organic matter levels and hence soil quality.

    In addition, under rainfed agriculture, the application of nutrients and organic matterthrough external sources is generally low, largely because of water scarcity, socioeconomicconditions of the farmers and the competing use of the crop residues; and the use of mineralfertilizers is confined to irrigated crops. Moreover, due to prevailing high temperature, dryingand wetting cycles and low inputs of organic matter, the organic matter levels in the SATsoils are very low and usually present a declining trend.

    *Corresponding author. Email: S.WANI@cgiar.org

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  • 720 S.P. Wani et al.

    Policy-makers, development agencies and researchers face a need for sustainable develop-ment and an obligation to improve the livelihoods of millions of poor in the SAT to meet theMillennium Development Goal (MDG) by 2015. The decline in agricultural productivity ofthe SAT soils can at least be partly attributed to human activity which has reduced soilquality. There is a direct link between soil quality and agricultural productivity on the onehand, and soil organic carbon (C) and soil quality on the other [13].

    In the SAT, rainwater management is used in a holistic, watershed management approachto increase agricultural productivity and incomes by enhancing rainwater use efficiencythrough improved soil quality, efficient water and nutrient management options along withimproved crops, cultivars and pest management practices [4]. The main objective of thispaper is to offer a synthesis of research which demonstrates how C sequestration in the SATsoils could be enhanced. This would reduce poverty through sustainable development, usingrainwater management as an entry point.

    Results and discussion

    Agricultural management practices influence the soil quality. This in turn impacts theproductivity of soils. An increase in the soils organic carbon pool favourably influences cropproductivity by increasing the water holding capacity of the soil; improving the soilsphysical properties, especially soilwaterair relations and improved supply of nutrients[3,57]. Moreover, the soils organic carbon pool drives soil biological activity, whichcontrols nutrient availability and overall nutrient cycling [8].

    Rainfed agriculture is predominant (80%) globally. In developing Asia, it constitutes6065% and in Africa almost 9095% [9]. Unlike the holistic approach taken for irrigatedagriculture in green revolution areas in Asia, rainfed subsistence agriculture has been dealtwith in compartments, such as soil conservation, water management, improved cultivars,fertilizer application, etc. The full potential of the technologies has not been realized norhave these been adapted on a sufficiently large scale to have substantial impact.

    In Asia, a number of countries adopted a watershed management approach to develop rain-fed agriculture to increase agricultural productivity. In India, until 2006, the Government ofIndia invested about US$ 6 billions treating 38.5 M ha through a watershed developmentprogram. However, average crop yields under rainfed agriculture hover around 11.5 t ha1

    and are much lower than the achievable potential yields [9]. Meta-analysis of 311 casestudies of watershed projects in India revealed that although watershed programs silentlyrevolutionized rainfed agriculture, their vast potential could not be harnessed because of thecompartmental approach, lack of community participation, inappropriate institutions, thelack of technical support, etc. [10].

    Wani et al. [3] reported the results of a long-term heritage watershed experiment initiatedin 1976 at the ICRISAT Centre, Patancheru, Andhra Pradesh, under rainfed conditions to testthe hypothesis that an improved system of catchment management in combination with anappropriate cropping system can sustain increased productivity and improve the soil qualityof Vertisols, compared with the existing traditional farming practices. The improved systemconsisted of implementing soil and water conservation practices, with excess rainwater beingremoved in a controlled manner. The soil and water conservation practices were combinedwith improved, legume-based crop rotation and improved nutrient management. In thetraditional system, sorghum or chickpea was grown in the post-rainy season with organicfertilizers, and in the rainy season, the field was maintained as a cultivated f

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