the role of sustainable agriculture and renewable-resource management in reducing greenhouse-gas...

7/31/2019 The Role of Sustainable Agriculture and Renewable-resource Management in Reducing Greenhouse-gas Emissions and Increasing Sinks in China and India.

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doi: 10.1098/rsta.2002.1029, 1741-17613602002Phil. Trans. R. Soc. Lond. A

J. N. Pretty, A. S. Ball, Li Xiaoyun and N. H. Ravindranath

increasing sinks in China and India

gas emissions andreducing greenhouseresource management inrenewable

The role of sustainable agriculture and

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10.1098/rsta.2002.1029

The role of sustainable agriculture and

renewable-resource management inreducing greenhouse-gas emissions and

increasing sinks in China and India

B y J. N. P r e t t y1, A. S. B a l l1, L i X i a o y u n2

a n d N. H. R a v i n d r a n at h3

1Centre for Environment & Society and Department of Biological Sciences,University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK

2College of Rural Development, China Agricultural University,West Yuan Ming Yuan Road, Beijing 100094, China

3Centre for Ecological Sciences, Indian Institute of Science,Bangalore 560 012, India

Published online 25 June 2002

This paper contains an analysis of the technical options in agriculture for reducinggreenhouse-gas emissions and increasing sinks, arising from three distinct mecha-

nisms:(i) increasing carbon sinks in soil organic matter and above-ground biomass;

(ii) avoiding carbon emissions from farms by reducing direct and indirect energyuse; and

(iii) increasing renewable-energy production from biomass that either substitutesfor consumption of fossil fuels or replaces inecient burning of fuelwood or cropresidues, and so avoids carbon emissions, together with use of biogas digesters

and improved cookstoves.

We then review best-practice sustainable agriculture and renewable-resource-man-agement projects and initiatives in China and India, and analyse the annual netsinks being created by these projects, and the potential market value of the carbonsequestered. We conclude with a summary of the policy and institutional conditionsand reforms required for adoption of best sustainability practice in the agriculturalsector to achieve the desired reductions in emissions and increases in sinks.

A review of 40 sustainable agriculture and renewable-resource-management pro-jects in China and India under the three mechanisms estimated a carbon mitigation

potential of 64.8 MtC yr1 from 5.5 Mha. The potential income for carbon mitiga-tion is $324 million at $5 per tonne of carbon. The potential exists to increase this byorders of magnitude, and so contribute signicantly to greenhouse-gas abatement.

One contribution of 20 to a special Theme Issue `Carbon, biodiversity, conservation and income:an analysis of a free-market approach to land-use change and forestry in developing and developedcountries.

Phil. Trans. R. Soc. Lond. A (2002) 36 0, 1741{1761

1741

c 2002 The Royal Society

http://rsta.royalsocietypublishing.org/http://rsta.royalsocietypublishing.org/http://rsta.royalsocietypublishing.org/


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1742 J. N. Pretty and others

Most agricultural mitigation options also provide several ancillary benets. How-ever, there are many technical, nancial, policy, legal and institutional barriers toovercome.

Keywords: sustainable agriculture; renewable energy;

avoided emissions; carbon sequestration; China; India

1. Technical options for reducing or avoiding emissions and

increasing sinks in agricultural systems

The 1997 Kyoto Protocol to the UN Framework Convention on Climate Changeestablished an international policy context for the reduction of carbon emissions andincreases in carbon sinks in order to address the global challenge of anthropogenicinterference with the climate system. It is clear that both emission reductions andsink growth will be necessary for positive eects on mitigation of current climate-

change trends (FAO 2000; Watson et al. 2000; IPCC 2001; The Royal Society 2001).A source is any process or activity that releases a greenhouse gas (GHG), or

aerosol or a precursor of a GHG into the atmosphere, whereas a sink is a mecha-nism that removes these from the atmosphere. Carbon sequestration is dened asthe capture and secure storage of carbon that would otherwise be emitted to orremain in the atmosphere. Agricultural systems emit carbon through the direct useof fossil fuels in food production, the indirect use of embodied energy in inputs thatare energy-intensive to manufacture, and the cultivation of soils and/or soil erosionresulting in the loss of soil organic matter. The direct eects of land use and land-use

change (including forest loss) led to a net emission of 1.7 GtC yr1

in the 1980s and1.6 GtC yr1 in the 1990s (Watson et al. 2000).

On the other hand, agriculture is also an accumulator of carbon when organicmatter is accumulated in the soil, and when above-ground biomass either acts as apermanent sink or is used as an energy source that substitutes for fossil fuels andso avoids carbon emissions. We identify three mechanisms and 21 technical options(table 1) by which positive actions can be taken by farmers by

(i) increasing carbon sinks in soil organic matter and above-ground biomass;

(ii) avoiding carbon dioxide or other GHG emissions from farms by reducing directand indirect energy use; and

(iii) increasing renewable-energy production from biomass that either substitutesfor consumption of fossil fuels or replacing inecient burning of fuelwood orcrop residues, and so avoids carbon emissions.

There is considerable scientic uncertainty over the causes, magnitudes and perma-nence of carbon sinks and emissions in agriculture and land use. We review availablemeasures under these three mechanisms, and indicate where sink creation and emis-sions avoidance can be achieved.

2. Mechanism A. Increase carbon sinks in soil organic matter

and above-ground biomass

Long-term agricultural experiments in Europe and North America indicate that soilorganic matter (SOM) and carbon are lost during intensive cultivation, typically

Phil. Trans. R. Soc. Lond. A (2002)



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Sustainable agriculture and renewable-resource management 1743

Table 1. Mechanisms and measures for increasing carbon sinks and reducing carbon dioxideand other GHG emissions in agricultural systems

(Adapted from Ravindranath & Ramakrishna (1997), Lal et al. (1998), Watson et al. (2000),Robertson et al. (2000), Wenhua (2001) and Pretty & Ball (2001).)

Mechanism A. Increase carbon sinks in soil organic matter and above-ground biomass

Replace inversion ploughing with conservation-tillage and zero-tillage systems

Adopt mixed rotations with cover crops and green manures to increasebiomass additions to soil

Adopt agroforestry in cropping systems to increase above-ground standing biomass

Minimize summer fallows and periods with no ground cover to maintain soil-organic-matter stocks

Use soil conservation measures to avoid soil erosion and loss of soil organic matter

Apply composts and manures to increase soil-organic-matter stocks

Improve pasture/rangelands through grazing, vegetation and re managementboth to reduce degradation and increase soil organic matter

Cultivate perennial grasses (60{80% of biomass below ground) rather thanannuals (20% below ground)

Restore and protect agricultural wetlands

Convert marginal agricultural land to woodlands to increase standing biomass of carbon

Mechanism B. Reduce direct and indirect energy use to avoid GHG emissions(carbon dioxide, methane and nitrous oxide)

Conserve fuel and reduce machinery use to avoid fossil-fuel consumptionUse conservation or zero tillage to reduce CO2 emissions from soils

Adopt grass-based grazing systems to reduce methane emissions from ruminant livestock

Use composting to reduce manure methane emissions

Substitute biofuel for fossil-fuel consumption

Reduce the use of inorganic N fertilizers (as manufacture is highly energy intensive),and adopt targeted- and slow-release fertilizers

Use integrated pest management to reduce pesticide use(avoid indirect energy consumption)

Mechanism C. Increase biomass-based renewable-energy productionto avoid carbon emissions

Cultivate annual crops for biofuel production, such as ethanol from maize and sugar cane

Cultivate annual and perennial crops, such as grasses and coppiced trees,for combustion and electricity generation, with crops replanted each cyclefor continued energy production

Use biogas digesters to produce methane, so substituting for fossil-fuel sources

Use improved cookstoves to increase eciency of biomass fuels

showing exponential decline after the rst cultivation of virgin soils, but with steadyloss continuing for many decades (Arrouays & Pelissier 1994; Reicosky et al. 1995,1997; Rasmussen et al. 1998; Robert et al. 2001; The Royal Society 2001). Botherosion and biological oxidation remove carbon from soils. Conventional ploughing




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exposes soil to solar radiation, mixes residues into soil, and adds air to macropores,all leading to an increase in metabolic rate of microbial populations. The greatestlosses of soil carbon and organic matter occur under intensive and continuous cereals(0.105 to 0:460 tC ha1yr1), and fell when mixed rotations and cover crops arecultivated (0.033 to 0:065 tC ha1yr1).

But SOM and soil-carbon pools can be increased with sustainable managementpractices. SOM has a stabilizing eect on soil structure, improves moisture reten-tion, and protects against erosion (Fliessbach & Mader 2000; Six et al. 2000). Long-term comparative studies show that organic and sustainable agricultural systemsimprove soil health through accumulation of organic matter and soil carbon, withaccompanying increases in microbial activity, in the USA (Lockeretz et al. 1981;Petersen et al. 2000), Germany (El Titi 1999; Tebrugge 2000), the UK (Jordan& Hutcheon 1994; Smith et al. 1998), Switzerland (FiBL 2000), and New Zealand(Reganold et al. 1987, 1993). Substantial increases in SOM occur with use of legumes

and manures (Drinkwater et al. 1998; Lal et al. 1998; Tilman 1998; Petersen et al.2000).

Recent years have seen rapid adoption of `conservation-tillage and `zero-tillage(ZT) systems, rst in the Americas, and now increasingly in Asia. In Brazil,Argentina and Paraguay, there were 26 million hectares of agriculture under ZTin 2001; up from 0.5 Mha in 1991 (Landers 1999; Petersen et al. 1999; Peiretti 2000;WCCA 2001). These systems of cultivation maintain a permanent or semi-permanentorganic cover on the soil, comprising either a growing crop or dead organic matterin the form of a mulch or green manure. The function is to protect the soil physi-

cally from the action of sun, rain and wind, and to feed soil biota, thus reducing soilerosion and improving SOM and carbon content. Smith et al. (1998) reviewed long-term experiments comparing conventional tillage with ZT in UK and Germany, andconcluded that, with ZT, SOM increases at 0.73% per year; and soil carbon increasesat 0.39 tC ha1 yr1. This compares with low estimates of net sequestration underZT of 0.1{0.3 tC ha1 yr1, and higher ones of 0.63{0.77 tC ha1 yr1 in Spain andCanada (Edwards et al. 1992; Lal et al. 1998), though some have found declines insoil carbon under ZT (Katterer & Andren 1999).

Watson et al. (2000) reviewed the carbon-sequestration potential of changing land-

use management towards more sustainable practices, and concluded that the greatestdividend comes from conversion of arable to agroforestry arising from both increasedSOM and above-ground woody biomass (table 2). Biomass used for energy produc-tion additionally avoids carbon emissions if it substitutes for fossil-fuels.

Carbon sequestration potential is higher in areas of humid temperate (0.1{0.5 tC ha1 yr1) than in semi-arid and tropical areas (0.05{0.20 tC ha1 yr1) (Lalet al. 1998). Palm et al. (2000) measured carbon stocks, losses and rates of accumula-tion in the tropics, and concluded that carbon accumulation rates are higher in above-ground biomass (at least 2 tC ha1 yr1) than in soils (0.2{0.6 tC ha1 yr1). Tree-

based agroecosystems, either plantation crops (e.g. oil palm, cacao and rubber) or onsmallholder farms, bring the greatest dividend, accumulating 3.0{9.3 tC ha1 yr1

(Sanchez et al. 1999). For this study, we use conservative rates of carbon accumula-tion under basic sustainable agricultural systems of 0.3{0.6 tC ha1 yr1, rising to0.66{1.3 tC ha1 yr1 with mixed rotations and cover crops, and to several tonnesper hectare when trees are intercropped in cropping and grazing systems.




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Table 2. Carbon sequestration in various land-use systems

(The period covered is 30{50 years after conversion or adoption. Data taken from Watson et al.(2000). (1) Carbon accumulated under improved management within a land use (tC ha1 yr1 ).(2) Carbon accumulated with land-use change tC ha1 yr1 ).)

land-use system (1) (2)

sustainable cropland management (reduced or zero-tillage,rotations, cover crops and green manures, animal manures andcomposts)

0.32{0.36 |

grazing land management (management of herds, wood, plantsand re)

0.53{0.80 |

rice paddies (plant residues, irrigation and inorganic/organicfertilizers)

0.5 |

agroforestry (management of trees on cropland) 0.22{0.50 3.10

forest management (forest regeneration, choice of species,fertilization, reduced degradation)

0.31{0.53 |

urban land management (tree planting, waste management) 0.30 |

conversion of arable to grassland | 0.80

wetland restoration (conversion of drained land back to wetlands) | 0.40

degraded land restoration (to crop, grass or forest land) | 0.25

3. Mechanism B. Reducing direct and indirect energy use toavoid carbon emissions

As an economic sector, agriculture also contributes to carbon emissions through thedirect and indirect consumption of fossil fuel, and a wide range of approaches toenergy accounting have been developed (Steinhart & Steinhart 1974; Leach 1976;Pimentel 1980; Dovring 1985; OECD/IEA 1992; Pretty 1995; Cormack & Metcalfe2000). Most commonly, conventions state that direct energy represents what is imme-diately vulnerable to supply interruptions. With the increased use of nitrogen fertil-izers, pumped irrigation and mechanical power in industrialized agricultural systems,

all of which are particularly energy intensive, agriculture has become progressivelyless energy ecient over time. These three sources account for 90% or more of thetotal direct and indirect energy inputs to most farming systems. Thus low-input ororganic rice in Bangladesh, China, and Latin America is 15{25 times more energyecient than irrigated rice produced in the USA. For each tonne of cereal or veg-etable from high-input systems, 3{10 GJ of energy are consumed in its production.But for each tonne of cereal or vegetable from low-input systems, only 0.5{1.0 GJare consumed (Pretty 1995).

In this study, we are concerned with the contribution that production systems low

in both direct and indirect energy use make to carbon emission avoidance. Sustain-able agricultural systems that substitute goods and services derived from nature forexternally-derived fertilizers, pesticides and fossil-fuels increase the energy-eciencyof food production (Pretty 1995, 1998; Pretty & Ball 2001). For example, ZT sys-tems have an additional benet to SOM accumulation of requiring less fossil fuel formachinery passes. Fuel use in conventional systems in the UK and Germany varies




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from 0.046{0.053 tC ha1 yr1 (Smith et al. 1998; Tebrugge 2000), whereas for ZTsystems, it is 0.007{0.029 tC ha1 yr1.

We use standard data on the energy used for various agricultural practices andinputs to calculate the avoided carbon emissions by reducing or changing these prac-tices (table 3). The amount of carbon produced per unit of energy used depends

on the contributions made by non-renewable and renewable sources to the domesticenergy sector in question. These vary from 24 kgC GJ1 for coal, 19 kgC GJ1 for oil,and 14 kgC GJ1 for natural gas (DTI 2001). As the adjustments for renewable andnon-renewable resources vary from country to country, we use 15 and 24 kgC GJ1

as the two conversion factors.Thus the application of 176kgN ha1 (the annual average for China, where 24.4 Mt

are consumed on 138 Mha) results in carbon emissions of 0.172{0.276 tC ha1, andso a substitution of legumes for these fertilizers would avoid these losses (the aver-age for India is 73.5 kg ha MJ ha1 of cropland, resulting in annual losses of 0.072{

0.115 tC ha1

). Eliminating one ploughing pass avoids 0.021{0.034 tC ha1

, andreducing insecticide use from 5 kg active ingredient per hectare to zero would avoid0.015{0.022 tC ha1. Hence a shift from an intensive plough-based system to a ZTsystem based on legumes for fertility and using no pesticides (Petersen et al. 1999)would save 0.23{0.37 tC ha1 in addition to any carbon sequestered in SOM. Themain contributor to avoided emissions comes from reducing nitrogen fertilizer use.

In the analyses in this paper, the transformations in the agricultural systemsanalysed tend not to involve shifts from high-input (high-energy) to low-input sys-tems. Most are contexts where farmers have little access to or income for externalinputs, and so the challenge is to nd the best ways to increase productivity usinglocally-available resources. However, 13 of the projects have seen modest declines inthe use of external inputs. For fertilizers, most reductions have been of the order of30{50 kg ha1, though in one case in southern India, more than 200 kg ha1 havebeen saved (Fernandez 1999; Myers & Stolton 1999). Signicant pesticide reductionshave occurred in integrated pest management programmes in rice, particularly whereaquaculture or diverse cropping patterns have been introduced (Eveleens et al. 1996;Zhu et al. 2000; Wenhua 2001).

4. Mechanism C. Increase biomass-based renewable-energyproduction to avoid carbon emissions

The third mechanism for agricultural systems to reduce net emissions and/or increasesinks is through the production of renewable energy from biomass. Biomass avoidsGHG emissions by providing energy for heat and electricity generation, and for trans-portation fuel. The avoided carbon emissions avoided are thus equal to the fossilfuels substituted by the biomass energy (or woody fuels substituted by more ecientbiomass systems and stoves) minus the carbon emitted by the biomass system. Ifbiomass is harvested and burned, and the same area replanted or regenerated, there

are no net carbon emissions over the harvest cycle. Land only used once provides atemporary benet by avoiding fossil-fuel consumption. However, if biomass burningwere substituted for energy derived from hydroelectric, wind, geothermal or nuclearsources, then it would represent a net source of carbon.

Several options are available for the production of renewable energy from biomassand for emissions avoidance.




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Table 3. Energy consumed and carbon produced by various agricultural inputs and practices

indirect andinputs and direct energy used carbon emitted at carbon emitted atpractices (MJ kg1 or ha1 ) 0.015 kgC GJ1 0.024 kgC GJ1

fertilizersnitrogen 65.3 MJ kg1 0.98 MJ kg1 1.57 MJ kg1

phosphorus 7.2 MJ kg1 0.11 MJ kg1 0.17 MJ kg1

potassium 6.4 MJ kg1 0.10 MJ kg1 0.15 MJ kg1

pesticides

herbicides 238 MJ kg1 3.57 MJ kg1 5.71 MJ kg1

fungicides 92 MJ kg1 1.38 MJ kg1 2.21 MJ kg1

insecticides 199 MJ kg1 2.99 MJ kg1 4.48 MJ kg1

applications

one spray per season 195 MJ ha1 2.93 MJ ha1 4.68 MJ ha1

one fertilizer pass 161 MJ ha1 2.42 MJ ha1 3.86 MJ ha1

one plough pass 1400 MJ ha1 21.00 MJ ha1 33.60 MJ ha1

(i) Cultivation of annual crops for biofuel production, such as maize and sugarcane for ethanol production.

(ii) Cultivation of annuals and perennials, such as grasses (e.g. Miscanthus) andagroforestry (e.g. fast-growing coppiced willow and poplar), for combustion

and electricity generation; and the use of plant products, such as crop residues(e.g. maize cobs, cereal straw, rice husks) or wastes (e.g. chicken manure) forcombustion for electricity generation through small-scale gas turbines.

(iii) Use of biogas digesters for methane production for light and heat, togetherwith other rural-based renewable electricity generation (e.g. solar stoves andsolar heating panels).

(iv) Use of improved cookstoves to increase combustion eciency of fuelwood, cropresidues and dung for cooking.

Some of these options have become common locally in some countries, but have notyet received widespread attention for their net carbon sequestration and emissions-avoidance potential. In Brazil, ethanol derived from sugar-cane biomass is blendedwith fossil fuels, and led to the avoidance of 9.2 MtC yr1 emissions in both 1997and 1998, some 11% of the countrys fossil-fuel CO2 emissions (Watson et al. 2000).In both China and India, sugar-cane biomass is burned for electricity production(Shukla 1998).

Agroforestry represents an important option for agricultural systems, as treessequester more carbon in woody biomass than cropping or pasture systems can do

in soils. The USDA (2000) suggests that carbon sequestration under agroforestrycan be higher than the IPCC estimates (see table 2). Short rotation coppice (SRC)gives a double benet through carbon sequestration and energy substitution, if thewood is burned instead of a fossil fuel. Under such coppicing, soil carbon increasesby 6.6 tC ha1 yr1 over a 15-year rotation, and wood by 12{22 tC ha1 yr1. Silvo-pasture systems can lead to increases in soil C of 5 tC ha1 yr1 over 35 years,




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and plant carbon of 10.1 tC ha1 yr1. Smith et al.s (2000) review of Europeanexperiments concluded that woodland regeneration can lead to accumulation of3.43 tC ha1 yr1, and SRC to accumulation of 6.62 tC ha1 yr1.

A recent review of biomass energy options for the UK indicated that SRC canyield 10{18 t dry matter ha1 yr1, equivalent to 4.0{7.2 tC ha1 yr1, and Miscant-

hus can produce 12{25 tDM, equivalent to 4.8{10 tC ha1 yr1 (Grogan & Matthews2001). Below-ground pools of carbon also increase by 0.1{1.6 tC ha1 yr1 (Hansen1993; Grigal & Berguson 1998). A limitation on the spread of these systems comesfrom the cost of transportation of the wood, and the capital investment required tobuild the energy-generating plant (RCEP 2000; DEFRA 2001). One scenario for theEU suggests that if 10% of the agricultural land were devoted to these biofuel crops,and was combined with woodland regeneration, then this would lead to a reductionin emissions equivalent to the EUs commitment under the Kyoto Protocol (Smithet al. 2000; The Royal Society 2001). A study in India has shown that by dedicat-

ing 32 Mha (out of 66 Mha) of degraded land at a woody biomass productivity of4 t ha1 yr1 could produce biomass adequate for generating 100 TWh of electricityannually, meeting all the rural electricity needs as well as providing carbon mitigationbenet of 40 MtC annually (Ravindranath & Hall 1995).

Biomass accounts for 38% of energy use in developing countries (Sudha & Ravin-dranath 1999) and such use for energy generation creates no net accumulation ofcarbon levels in the atmosphere because the carbon released during combustion iscompensated for by that absorbed during growth. Biomass energy becomes a contri-bution to carbon-emissions avoidance if it substitutes for fossil-fuel use or electricity

derived from fossil fuels. In this paper, we limit our assessment to the contributionmade by rewood derived from agricultural systems, and not from forests (Ravin-dranath et al. 1997).

Biogas digesters to produce methane for cooking, lighting and heating have be-come widespread in China and India following progressive national policies to aidtheir adoption (Ministry of Agriculture 2000, 2001; Somashekhar et al. 2000; Wen-hua 2001). Animal waste and plant material are added to the digester to producemethane, and the remaining sediment, which is high in organic matter, is returned tothe soil. Fermentation in digesters occurs in three stages. Organic matter is hydrol-ysed into volatile organic acids, and those are then decomposed by bacteria into

acetic acid, hydrogen and carbon dioxide. They are then converted by methanogenicbacteria in the anaerobic part of the process to methane and carbon dioxide (usuallyin a volume ratio of 2:1). During the process, the C:N ratio needs to be ca. 10{20:1,and so plant materials, such as straw, are added as a carbon source, and animalwastes added as a nitrogen source.

Digesters are a net carbon sink if they substitute for fossil-fuel consumption orfor inecient wood or plant-residue combustion. In some contexts this is not thecase, as digesters have been adopted precisely because remote rural households donot have access to national electricity grids. Nonetheless, if they substitute for the

combustion of wood, crop residues and dung, there is still a net benet as less isburned for the same amount of energy, leaving more remaining as standing biomass,and as the digested sediment is returned to the soil.

There are 8.48 million biogas digesters in China, up from 4.5 million in 1990, withprojections for an additional million per year for 2001{2010 (Shuhong 1998; Ministryof Agriculture 2000). About 20% of these are incorporated into a variety of integrated




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models of production, such as the northern 4-in-1 model with biogas pit, pigsty,lavatory and greenhouse for vegetable production, and the southern models involvinglivestock-rearing with fruit, sugar cane, mulberry, sh and vegetables. There are,however, doubts that all these digesters are working to full eciency. The rate offunctioning has been poor, but has recently improved owing to the new Ministry of

Agriculture coordinated programme, and the proportion of well-functioning units isnow estimated to be 80{90%. In India, there are some 2.5 million family-sized biogasplants, constructed by the National Project on Biogas Development, plus another500 larger community biogas systems (Ravindranath & Ramakrishna 1997; Shukla1998; Somashekhar et al. 2000). Shukla (1998) estimates that, nationwide, 60% arefunctioning well (1.5 million units).

Depending on the size of these domestic digesters, their eciency and productiveperiod during the year, each can save the annual combustion of 1.5{4.0 tonnes offuelwood, equivalent to an avoided emission of 0.75{2.0 tC per digester (Shuhong

1998; Shukla 1998; Wenhua 2001). There are added benets from biogas systems.If straw is burned as fuel, only 10% of the energy is used. But energy use risesto 60% if the straw is used in a biogas digester. The 4-in-1 Chinese model alsoproduces ve tonnes of sediment each year, which is added to the soil. The contentis typically 0.8{2% nitrogen, and 30{50% organic matter, and so receiving soils arenot only improved for agricultural purposes, but their SOM and carbon contentincreases. The benecial side-eects of these digester systems include improved ruralsanitation, less labour required for collecting wood (especially for women), betterrespiratory health in kitchens, and increased per-hectare food production through

soil-health improvement and extended growing periods with greenhouses in colderregions (Chen et al. 1990; Ravindranath & Ramakrishna 1997).

Improved cookstoves represent another important option for avoided emissions indeveloping countries. Cooking is the dominant energy-using activity for rural house-holds, and also has a signicant eect on the quality of life of women. In India,women spend 4.3 hours a day cooking (Ravindranath & Ramakrishna 1997). Accord-ing to the Advisory Board on energy in India, 95% of rural households depends onnon-commercial energy derived from agricultural and forest resources, particularlyfuelwood, crop residues and dung. But unprocessed biomass fuel has a low energy

density and, combined with poor eciency of cooking devices, this means that percapita primary energy consumption in developing countries is 10.5 GJ yr1 com-pared with 2.5 GJ yr1 in industrialized countries (Ravindranath & Ramakrishna1997).

There is a wide range of improved cookstoves available (Ravindranath & Ramakr-ishna 1997; Shukla 1998; Shuhong 1998). In China, improved cookstoves are usedby 170 million households, up from 40 million in 1985. In India, there are 25.7 mil-lion units, up from 0.3 million in the mid-1980s. Each well-functioning stove saves0.4{1.0 tonnes of fuelwood per year, equivalent to 0.2{0.5 tC per household. In this

paper we do not assess the additional value of renewable but non-biomass-based ruralenergy generation. These, though, are making important contributions, such as the140 000 household-scale wind turbines with power production of 1.37 GJ installed inpastoral and coastal regions of China, the 332 000 solar cookers in use, each saving500{700 kg fuelwood each year, and 11 Mm2 of solar heaters with 38 PJ of annualenergy-saving capacity (Ministry of Agriculture 2000; Wenhua 2001).




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5. Review of b est-practice sustainable-agriculture

projects in China and India

In this section, we analyse net sequestration and emissions avoidance in China andIndia. We use a recently developed dataset on sustainable agriculture projects and

initiatives to assess progress being made on mechanisms A, B and C (increasing sinks,reducing energy use, increasing renewable-energy production). China and India wereselected as they have 46% of the worlds population (in 2001). Annual growth of car-bon emissions is 4.4% in China and 6.7% in India, and together they account for 45%of developing country emissions and 17% of global emissions (Sataye & Ravindranath1998), though per-capita emissions compared with industrialized countries are low.Though energy consumption in the agricultural sector is low compared with othersectors, the growth in agricultural consumption of energy is increasing more rapidly(5.2{6.5% yr1 in China in the 1990s) than growth in grain production (3.5% yr1

in China in the 1990s) (Wenhua 2001; CED 2001; US Energy Information Network2001a; b).Both countries also have large amounts of agricultural land, and so have many

opportunities for creating new carbon sinks. In India, there are 162 Mha of arableland, 7.9 Mha of permanent crops and 11 Mha of permanent pasture. In China, thereare 100 Mha of drylands, 38 Mha of paddy rice, and 300 Mha of low and high grass-lands (Wenhua 2001; FAO 2001). Consumption of inorganic nitrogen fertilizer isgrowing in both countries, and in 1999 was 24.4 Mt yr1 in China and 11.9 Mt yr1

in India (together accounting for 42% of world nitrogen consumption) (FAO 2001).As indicated earlier, nitrogen fertilizer is energy-intensive to manufacture, and thisconsumption of 36.3 Mt of N results in emissions of 36{57 MtC yr1. Both countriesuse large amounts of wood for energy production (11% of total energy in China and30% in India) (FAO-RWEDP 2000). In India, fuelwood consumption for domestichouseholds is 219 Mt yr1, crop residues 96 Mt yr1 and 37 Mt yr1 of cattle dung(Shukla 1998; Shuhong 1998; Ravindranath & Hall 1995). Finally, both countrieshave numerous novel examples of best practice in sustainable agriculture, and theseprovide the basic data for analysis of actual net carbon sinks currently being created,and their current economic value.

We dene agricultural sustainability as farming that makes the best use of natures

goods and services while not damaging the environment (Altieri 1995; Conway 1997;Pretty 1998, 2002; Hinchclie et al. 1999; NRC 2000). It does this by integratingnatural processes such as nutrient cycling, nitrogen xation, soil regeneration andnatural enemies of pests into food production processes. It minimizes the use ofnon-renewable inputs that damage the environment or harm the health of farmersand consumers. It makes productive use of the knowledge and skills of farmers, soimproving their self-reliance, and seeks to make eective use of peoples collectivecapacities to solve common resource management problems, such as in pest, water-shed, irrigation, forest and credit management.

We use a University of Essex dataset to assess progress being made on increasingcarbon sinks in sustainable agriculture systems (for details of research methodology,see Pretty & Hine (2000, 2001) and Pretty et al. (2002)). The research auditedprogress in developing countries, and assessed the extent to which farmers wereincreasing food production by using low-cost and locally available technologies andinputs. A total of 208 projects in 52 countries were analysed, comprising 45 projects




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in Latin America, 63 in Asia and 100 in Africa, in which 8.98 million farmers hadadopted sustainable agriculture practices and technologies on 28.92 Mha, up fromca. 0.5 Mha in 1990. We have added initiatives on biogas and improved cookstovesfor this analysis, bringing the total analysed here to 28 projects and initiatives fromIndia, and 12 from China (see Appendix A for list).

These 40 initiatives involve 209 million farm households (180.69 million in Chinaand 28.8 million in India), and cover 5.58 Mha (4.48 Mha in China and 0.75 Mha inIndia). We do not imply that these represent a comprehensive survey of all sustain-able agriculture initiatives in these two countries. Rather, we are interested in whatis already being achieved by a sample of best-practice, and what could be achievedif these principles were spread to a larger scale (more farmers and more hectares)with appropriate policies and institutions.

A variety of technical options is being used in these projects. Those contributing tomechanism A (increasing carbon sinks) include water harvesting in the drylands to

rehabilitate degraded lands; agroforestry; adoption of certied organic farming; inte-gration of livestock into systems, so increasing supply of animal manures; use of com-posts; watershed development programmes involving soil conservation; agroforestryand reforestation; and adoption of ZT systems. Those contributing to mechanism B(avoided emissions through reduced energy use) include inorganic fertilizers and pes-ticides; adoption of certied organic farming; more ecient use of water per kilogramof crop output through participatory irrigation management, thus reducing energyuse; and mixed rotations and multiple cropping to increase biocontrol of pests anddiseases. Those contributing to mechanism C (renewable-energy production) include

biogas digesters and improved cookstoves.We have no examples of programmes addressing pasture management, reduceddependency on concentrated feeds, or more ecient energy use in intensive pro-duction systems. We also do not assess the large-scale tree-planting programmes orforest-regeneration programmes in the two countries. In India, for example, 25 000

joint forest-management groups were formed in the 1990s, and these have substan-tially improved standing biomass and biodiversity of forests under their control(Shrestha 1997; Ravindranath et al. 2000). In China, four major shelterbelt systemshave been planted in the 1990s, bringing increases in carbon sequestration combinedwith local ecological benets. The Three North Shelterbelt stretches across 645 coun-

ties and 13 provinces, with 12.1 Mha planted in 11 years, and a further 6 Mha plannedfor 2001{2010. During the 1990s, 2 Mha of trees were planted in the Upper Yangstewatershed, 6 Mha along the coast, and 10 Mha of farmland incorporated into ruralshelterbelt networks in the plains of central China. Though many of these trees aretechnically in farmland rather than in forests, we do not include them in this analy-sis. The total carbon sequestration potential of forest regeneration depends in parton the durability of the end-use for the trees. Many Pawlonia grown in agroforestrysystems and shelterbelts, for example, are used for furniture, representing a fairlypermanent sink for carbon (Wenhua 2001).

We calculate the annual contributions being made in these projects to carbon-sinkincreases and emissions avoidance. Our focus is on what sustainable methods cando to increase marginal quantities of soil and above-ground carbon, and so we donot take account of existing stocks of carbon. We assessed each of the projects fortheir total contributions to mechanisms A, B and C, and calculated the net annualincrease in carbon (table 4). In the analysis, we apply an agroecological zone factor to




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correct soil-carbon sequestration for climate, as rates are higher in humid comparedwith dry zones, and generally higher in temperate than in tropical areas (Watson etal. 2000; Lal et al. 2000). However, given the longer growing season in the tropics,and greater potential for organic matter production, we correct soil sequestrationrates with the following ratios: 1:0 for humid tropical, 0:8 for humid temperate

and 0:4 for both dry temperate and dry tropical.

6. Spreading best practice with appropriate policies and measures

These 40 sustainable agricultural and renewable-resource-management projects aresequestering 27.3 MtC yr1 (mechanism A) and avoiding 37.5 MtC yr1 of emissions(mechanisms B and C), giving a total of 64.8 MtC yr1. This gives an average netgain of 11.61 tC ha1 yr1, and an average per household of 0.31 tC yr1. Mecha-nism B gives the smallest net benet of 12.6 ktC yr1, mainly because at the outset

these were mostly low-input systems. The biogas and cookstove programmes arecontributing 58% to the total, comprising 1.4 tC per household for biogas plants,and 0.14 tC for each cookstove. However, there are several important uncertainties,including the sustained eective use of energy-saving cookstoves and biogas plants,the longevity of the technologies, and the possibility that access to safe and abundantenergy will simply result in increased total use of energy by participating households.

At the lowest carbon prices in trading systems in current use ($2{$5 per tonne ofcarbon), this implies a potential income for these projects and households of $130{$324 million yr1. This rises to $648 million yr1 at medium rates ($10 per tonne of

carbon), and could be $1.6 billion yr

1

(at $25 per tonne of carbon). The rates ofsequestration in soils and above-ground biomass cannot be sustained indenitely inagricultural systems, as inputs and losses come into balance over a 20{50 year period(Watson et al. 2000). Rates of gain are generally greatest soon after adoption of newmanagement practices, and thus the benets of biological mitigation in agriculturalsystems will be most pronounced in the 2{3 decades after adoption of new policiesthat encourage such changes in farm practice.

Sustainable agricultural management can contribute signicantly to both net car-bon sequestration and to increased food production, as well as make a signicantimpact on rural peoples livelihoods. In the 208 projects analysed in 52 countries,

average per-hectare food production increased by 73%, and there were additionalbenecial side-eects through improvements in water tables (with more drinkingwater in dry seasons), reduced soil erosion combined with improved SOM, andincreased agrobiodiversity (Pretty et al. 2002). However, it is important to note thatthere may also be critical trade-os, with gains in carbon sequestration being osetby losses through increased energy use or emissions of trace GHGs, such as methaneand nitrous oxide (Watson et al. 2000). For example, water harvesting can lead toincreased SOM and higher cropping intensity, but can also increase annual fertilizer(and indirect energy) use. Increased productivity also increases the otake of nutri-

ents in food, which need to be replaced through nitrogen xation and/or importedsources, and incorporation of rice straw into paddy soils can increase methane emis-sions.

The important challenge now is to develop the appropriate support at a rangeof levels for these sustainable agricultural and renewable-resource-management ini-tiatives. Most of the projects analysed are relatively local in extent. The largest,




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though, have spread precisely because of explicit support and nance from national,sub-national and international levels. The 1990s saw considerable global progresstowards the recognition of the need for policies to support sustainable agriculture(Izac 1997; Pretty et al. 2001; Dobbs & Pretty 2001). In a few countries, this has beentranslated into supportive and integrated policy frameworks. In most, however, such

policies remain at the margins. A good example of an integrated programme comesfrom China, where the governments 1994 White Paper set out Shengtai Nongye, oragroecological engineering, as its approach to achieve sustainability in agriculture.Pilot projects have been established in 2000 townships and villages spread across150 counties. Policy for these `eco-counties is organized through a cross-ministrypartnership, which uses a variety of incentives to encourage adoption of diverse sys-tems to replace monocultures. These include subsidies and loans, technical assis-tance, tax exemptions and deductions, security of land tenure, marketing servicesand linkages to research organizations. These eco-counties contain 12 Mha of land,

and though only covering a relatively small part of Chinas total agricultural land,do indicate what is possible when policy is coordinated and integrated.If domestic policies elsewhere were to support the types of sustainable agriculture

in these projects that also sequester carbon and avoid emissions, then it is possibleto predict some of the potential benets. The average carbon sequestration ratesare 0.19 tC yr1 ha1 in the projects in China and India (not counting the biogasand stove projects, and the large-scale agroforestry programmes). The average perhousehold is 0.31 tC yr1.

These projects currently cover 5.58 Mha (or 1.8%) out of a total of 300 Mha ofarable land in the two countries. As indicated earlier, there has been extraordinarygrowth in sustainable agriculture in the 52 developing countries studied (up from0.5 to 29 Mha in 10 years). If these 5.6 Mha were to grow to 20% of all arable land inChina and India in a decade (to 60 Mha), then the annual carbon sequestered wouldbe 11 MtC ha1 yr1, worth $55{$275 million at trading prices of $5{$15 per tonneof carbon. Additional benets would arise from spread of agroforestry, biogas andcookstove programmes.

These values exceed the typical investment costs of $1.50{$10 per tonne of carbonfor agroforestry, enhanced natural resource management and sustainable agricul-ture projects in China and India (Sathaye & Ravindranath 1998). With appropriate

investments through participatory and community-based institutions to ensure per-sistence of new practices, combined with appropriate policy support at all levels, itis clear that the biological mitigation potential in China and India is large. Jointimplementation projects could increase the ow of new technology and investmentleading to additional environmental and social benets.

7. Barriers and integrated policy options

The majority of mitigation options are known to provide ancillary or co-benets

and thus opportunities for `win{win outcomes. However, there are many technical,nancial and institutional barriers (IPCC 2001). Adoption of new technology ormitigation options is limited by small farm size, credit constraints, risk aversion,lack of access to information, and inadequate rural infrastructure and land tenurearrangements. Moreover, subsidies for inputs to agriculture, such as fertilizers, watersupply and electricity and fuels distort markets for these products.




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Though much can be done with existing resources, there are always transition costsin learning, in developing new or adapting old technologies, in developing collectivemanagement institutions, and in breaking free from existing patterns of thought andpractice. Further issues such as lack of technical capability, lack of credibility aboutsetting project baselines, and monitoring of carbon stocks pose new challenges. In

the majority of developing countries, farmers lack access to technology and nanceand have little capacity to bear risk. There is, therefore, a need to develop nationallyrelevant technical, institutional and nancial policies to promote mitigation options,ensure that risk to small farmers is minimized, and raise crop productivity andincomes.

The ndings in this study that poor rural households and communities can con-tribute both to their own economic welfare through adoption of sustainable agricul-ture and renewable-resource-management methods, and to the global environmentalgood through biological carbon mitigation, raise important challenges for policy mak-

ers and project managers in the agricultural, forestry, energy, water and engineeringsectors. There is an urgent need for the integration of policies both across and withinthese sectors, so that technologies and social processes are adapted to the diverseneeds of local communities across a wide variety of environments and economies.

Appendix A. List of the 40 analysed best-practice sustainable

agriculture and renewable-resource-management

projects and initiatives in China and India

Zero-tillage projects1. Zero tillage of rice{wheat systems, Haryana (P. Hobbs, CIMMYT, personal

communication).

Watershed development and soil conservation projects

1. Xiji County comprehensive management of watersheds, Ningxia (W. K. Zhi,personal communication).

2. National pilot watersheds programme, China (Wenhua 2001).

3. Loess plateau soil and water conservation project, China (Wenhua 2001).

4. UNDP poverty alleviation and sustainable development project, Yunnan(Y. Yunsong, personal communication).

5. Hebei Plain wheat{maize double-cropping project (L. Weili, personal commu-nication).

6. East Gansu sustainable agricultural for eective use of rainfall resources(F. Tinglu, personal communication).

7. Rural communes comprehensive watershed development, Maharashtra (M.Alavi & R. Joshi, personal communication).

8. Rajasthan watershed development programme (Krishna 1999).

9. EZE sustainable agriculture, Bangalore (EZE, Banglalore).




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10. World Neighbours dryland farming projects, India (World Neighbours).

11. ActionAid watershed projects, Karnataka, Tamil Nadu, Uttar Pradesh andMadhya Pradesh (ActionAid).

12. Aga Khan Rural Support Programme, Gujarat (Shah & Shah 1999).

13. Participative Integrated Development of Watersheds project, Karnataka (Fer-nandez 1999).

14. Indo-German watershed development project, Maharashtra (Lobo & Palghad-mal 1999).

15. Society for Peoples Education and Economic Change, Tamil Nadu (Devavaramet al. 1999).

16. Doon Valley Integrated Watershed Development project, Uttar Pradesh (Thap-liyal et al. 1999).

17. KRIBCHO Indo-British Rainfed Farming Project (West) (P. S. Sodhi, personalcommunication).

18. Womens Sangams of Deccan Development Society, Andra Pradesh (Sateesh &Pimbert 1999).

19. Karnataka watershed development projects (funded by DFID, Danida, KfW)(Ninan 1998).

20. Tamil Nadu watershed development projects (GOTN 2001).

21. National Council of Development Communication (V. K. Dubey, personal com-munication).

Mixed sustainable agriculture and agroforestry projects

1. Pawlonia agroforestry and intercopping programme, China (Wenhua 2001).

2. Learning by Doing cotton project, Punjab (P. Guest, personal communication).

3. M. S. Swaminathan Research Foundation integrated intensive farming systems,Tamil Nadu (V. Balaji, personal communication).

4. N. Kolar tamaraind agroforestry project, Karnataka (N. H. Ravindranath, per-sonal communication).

5. Maikaal organic cotton project, Madhya Pradesh (Myers & Stolton 1999).

6. Non-pesticidal management, Nellore: Centre for World Solidarity (S. A. Sha-

unnisa, personal communication).7. Technology assessment through Institutional Village Linkage, Karanataka

(G. K. Veeresh, personal communication).

8. Praja Abyudaya Samastha, Andra Pradesh (M. Balavardiraju, personal com-munication).




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9. Ankapur village project, Nizamabad (V. Balasubramanian, personal commu-nication).

Irrigated rice and pest management projects

1. Multiline rice cultivation, Yunnan (Zhu et al. 2000).

2. Paddy-rice aquaculture systems, China (Li Kangmin 1998; Wenhua 2001).

3. Rice-IPM national programme, China (Eveleens et al. 1996; Mangan & Mangan1998).

4. Rice-IPM national programme, India (Eveleens et al. 1996).

5. Gujarat Participatory Irrigation Management programme (R. Parthasarathy,personal communication).

Biogas and improved cookstove projects

1. National biogas programme, China (Ministry of Agriculture 2000, 2001; Wen-hua 2001).

2. National biogas programme, India (Ravindranath & Ramakrishna 1997).

3. National improved cookstoves programme, China (Shuhong 1998).

4. National improved cookstoves programme, India (Ravindranath & Ramakr-

ishna 1997; Shukla 1998).

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