Climate Change and Indian Agriculture
Indian agriculture has don remarkably well by increasing food production from 50 Mt in 1951 to 212 Mt in 2002 and assuring food security to the nation, in spite of a steady increase in the population to 1.2 billion presently. However, perceived impacts of climate change could adversely affect the food output that need to increase by 56, 62, 36 and 116 percent for rice, wheat, coarse cereals and pulses respectively by 2020. India is anticipated to suffer severely from potential changes in temperature and precipitation emanating out of climate change. While many of the key prevention and mitigation measures are global in nature, every nation has a responsibility to contribute to preventing further imbalance between carbon emission and attendant climate change impacts and protect the global heritage of food production.
Climate Change Consequences
Climate change involving alterations in temperature, precipitation and sea level rise as well as increased incidence of UV-B radiation, is a distinct possibility in the not too distant future. 
Considerable evidence is now available which suggest that human activities have altered the concentration of key trace gases in the earth’s atmosphere. Because these gases (CO2, CH4, N2O and CFCs) are transparent to incoming radiation but can trap part of terrestrial long-wave radiation (heat wave) reflected back into space, they may lead to an increase in the global surface temperature and consequent climate change. Overall, this has come to be known as ‘Greenhouse effect’.
 Atmospheric CO2 concentration has increased from 280 ppm V in pre-industrial era to ~ 380 ppm V at present and potentially to 700 ppm V towards the end of the twenty- first century (IPCC, 2007). Similarly, other greenhouse gases like CH4, N2O and tropospheric Ozone (O3) have increased 152%, 18% and 36% respectively. The high global warming potential (GWP) of CH4 [GWP = 23 for the 100 year horizon] and N2O [GWP = 296 for the 100 year horizon] relatively to CO2 [GWP = 1] amplifies the effect of these gases on climate. As a consequence of the build-up of atmospheric CO2 and other greenhouse gases in the atmosphere, Earth’s surface temperature has increased by 0.740C since 1850 and is expected to increase by another 1.10C ~ 6.40C by the end of this century (IPCC 2007).
Change of Global temperature and CO2 concentration over the Years
Although climate change and its consequences are uncertain and not predetermined, its potential importance is such that much effort has been given to determine the sources and radiative effects of these trace gases. The projected climate changes are expected to usher in severe biophysical responses in agro-ecosystems and agricultural crops in particular, either through direct effect of increased CO2 concentration on crop growth and yield including tolerance to moisture stress or through indirect effects on crops through crop-pest interaction, changes in hydrological regimes and soil processes.
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Drought |
Erosion |
Cyclone |
However, the whole process may be further influenced due to interaction of increased greenhouse gas (GHG) concentrations and the resultant high temperature. It has been estimated that 20% or more of targeted emission reduction could be met by agricultural carbon sequestration.
SOC Dynamics and Feedback to Climate Changes
The soil organic carbon and its temperature sensitivity have recently received considerable attention especially in their decomposition parameters. In the event of carbon stored belowground is transferred to the atmosphere by a warming- induced acceleration of its decomposition, a positive feedback to climate change would occur. Alternatively, if increases of plant-derived carbon inputs to soils exceed increases in decomposition, the feedback would be negative. Moreover, several environmental constraints obscure the intrinsic temperature sensitivity of substrate decomposition, causing lower apparent temperature sensitivity and these constraints themselves are temperature sensitive. Positive or negative feedbacks of terrestrial C cycles to climate warming may be sensitive to climate. The potential to carbon storage in soils by increasing cropping intensity and management inventories in sub-tropical climate areas could contribute positively in mitigating agriculture effect on atmospheric CO2 levels and its effect on global climate change. The beneficial effect of SOC is more than improving soil quality and fertility. It’s hidden value lies in its ability to moderate the green- house effect on the environment by reducing atmospheric enrichment of CO2.
Microorganisms not only influence but also regulate the rate of organic matter decomposition. Microorganisms and their activities are the main mediators of C and N turnover in the soil. Microbial biomass regulated by substrate and water availability, temperature, climatic regime and soil structure is considered as a transformation agent for soil organic matter and a labile pool of organic and inorganic nutrients. The regulatory role played by microbial communities and signifies the interactive credentials of independent microbial groups in impacting the organic- C dynamics in soil creating negative or positive feedback to climate change.
Accordingly, we need to understand how substrate availability will change and how a changing set of environmental constraints to decomposition in a future climate will determine the future apparent temperature sensitivity of decomposition. There is an urgent need for more empirical knowledge that will fundamentally improve our ability to predict feedbacks of the terrestrial carbon cycle in agricultural ecosystems to anticipated climate change.
Objectives
- To evaluate the interactive effect of elevated greenhouse gases (CO2, CH4 and N2O), temperature, hydrological and microbiological relations on soil carbon decomposition and nutrient release, and their impact on climate change.
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- To monitor in situ gaseous-C and N emission in three major cropping systems and relate them to soil physico-chemical and microbiological parameters.
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- To study intervention points for devising adaptation strategies to manage C flux in three major cropping systems.
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Innovations
- Catalogue feedback effects of soil organic carbon under different cropping systems on the greenhouse effect.
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- The apparent temperature sensitivity of substrate decomposition that can lead to moderate the greenhouse gases and improve environmental quality, leading to more efficient and environment-friendly agriculture will be studied.
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- Impact of management practices on potential enhancement of soil organic carbon storage, reduce gaseous-C emission and sustain yield.
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- Determine degradation equilibrium and kinetics of different soil organic matter fractions.
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Research Approaches
- Factors controlling decomposition of organic matter.
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- Characterization and quantification of plant-derived C-inputs and externally added inputs on SOC pools and their environment linkage.
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- Environmental constraints affecting temperature sensitivities of decomposition.
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- Microbial diversity in the organic matter decomposition and its feedback to climate change.
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- Evidence for a decomposition feedback to warming.
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Deliverables
Outputs
- Interactive effects of elevated greenhouse gases (CO2, CH4 and N2O), temperature, hydrological and microbiological relations on soil C decomposition and nutrient release.
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- Information on the relationship between the soil organic carbon and ambient temperature under different cropping systems.
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- Two process-based models for prediction of gaseous- C emission and soil-C storage under varying temperature and greenhouse gas concentrations.
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- Strategies on organic matter management and resource conservation for mitigation of gaseous-C emission under the three cropping systems.
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Outcomes and Anticipated Impacts
The most important outcome of the project would be to highlight and document the contribution of organic carbon on global warming in general by deriving an empirical relationship between soil C degradation equilibrium and kinetics under three major cropping systems (rice-wheat, rice-rice and rice-sugarcane) of India.
The knowledge will help us to predict gaseous-C emission and soil C storage under changed climate and have fundamental understanding on the nature of feedbacks (positive/negative) of gaseous-C emissions on climate change. Reduction of carbon loss through gaseous emission from the present 2.7% to ~ 2% under tropical condition would lead to a negative impact on global warming.
Execution of the program will guide us to devise strategies on organic matter management and resource conservation for mitigation of gaseous-C emission. While about 5.1% of the crop residues C incorporated into the soil can be stabilized into SOC it could be further enhanced (~ 1.5 times) by the judicious management of cropping practices including application of crop residues. This would ensure environmental safety, restoration of soil fertility and protection of yield decline from anticipated climate change.
Project duration: April 2008 to March 2012
Total budgetary cost: Rs. 480. 01 lakhs
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Research approaches to be taken and methods to be followed for addressing the objectives |
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Measurement of biogenic gaseous-C (CO2 and CH4) efflux
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Root exclusion method
In situ C flux measurement
Upscaling of data to ecosystem level through modeling |
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Characterization and quantification of SOC pools |
Analysis of active, slow and passive pools of SOC under ambient and elevated CO2 and temperature |
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Diversity analysis of microorganisms in the cycling of C and N under the impact of changed climate |
Functional and structural diversity analysis under ambient and elevated CO2 and temperature |
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SOC budgeting in major rice-based cropping systems |
Preparation of detailed SOC budget in major rice-based cropping system |
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Degradation kinetics of soil-C and integration of model kinetics |
Integration of Arrhenius and Michaelis-Menten kinetics to explain the impact of increased temperature on decomposition |
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Management strategies to reduce CO2 evolution under field conditions |
Three rice based cropping systems
Rice-Rice
Rice-Wheat
Rice-Sugarcane |
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Atmospheric CO2 concentration has increased from 280 ppm V in pre-industrial era to ~ 380 ppm V at present and potentially to 700 ppm V towards the end of the twenty- first century (IPCC, 2007). Similarly, other greenhouse gases like CH4, N2O and tropospheric Ozone (O3) have increased 152%, 18% and 36% respectively. The high global warming potential (GWP) of CH4 [GWP = 23 for the 100 year horizon] and N2O [GWP = 296 for the 100 year horizon] relatively to CO2 [GWP = 1] amplifies the effect of these gases on climate. As a consequence of the build-up of atmospheric CO2 and other greenhouse gases in the atmosphere, Earth’s surface temperature has increased by 0.740C since 1850 and is expected to increase by another 1.10C ~ 6.40C by the end of this century (IPCC 2007).
