1. Greenhouse Gas Emissions and Mitigation Measures in Agroecosystem
Jianping Guo
(Chinese Academy of Meteorological Sciences)
Presented by Chaodong Zhou for Jianping Guo
(China Meteorological Administration)

2. The purpose of this paper is to document the main production and emission processes of greenhouse gases in relation to agricultural production , and to examine the potential for reducing such emissions.
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3. CONTENTS Introduction I. General Emissions
II. Greenhouse Gas Emissions In Agroecosystems
III. Practices to Mitigate Greenhouse Gas Emissions In Agriculture
IV. Some Measures Of Greenhouse Gas Mitigation In China
V. Summary
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4. INTRODUCTION CO2, CH4 and N2O are the most important greenhouse gases.
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5. INTRODUCTION
CO2, CH4 and N2O are the most important greenhouse gases.
Atmospheric concentrations of CO2, CH4 and N2O are increasing annually by 0.5 %, 1.1 % and 0.3 % ,respectively. If greenhouse gas emissions continue to increase at the present rate, the average global temperature will increase by about 1 °C by the year 2025, and by 3 °C by the end of this century.
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6. I. GENERAL EMISSIONS CO2 CH4 N2O
CO2,CH4, N2O Emissions from Agriculture (Bouwman, 1990)
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7. I. GENERAL EMISSIONS CH4 N2O 12599-20090Gg 70-190Gg
CH4, N2O Emissions from Agriculture in China (ADB-GEF-UNEP,1998)
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8. I. GENERAL EMISSIONS N2O 0.096TgN
N2O Emissions from Farmland in China in 1990 (Song,1996)
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9. I. GENERAL EMISSIONS CH4 17.5±1.9Tg
CH4 Emissions from Rice Paddy in China in 1990 (Song,1996)
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10. 1. CH4 Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
1. CH4 Production and Emissions
Rice Paddies
CH4 emissions from rice paddy result from three processes.
A concentration gradient that causes diffusion through the soil-water and water-air interfaces.
The release of gas bubbles from soil surface to the atmosphere.
Soil CH4 that enters into the plant through the roots is released to the atmosphere through the plant stomata.
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11. 1. CH4 Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
1. CH4 Production and Emissions
Rice Paddies
Factors related to CH4 emissions from rice paddies :
Field
Soil temperature (in the 0-15 cm layer)
Soil water content
Soil Characteristic
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12. 1. CH4 Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
1. CH4 Production and Emissions
Rice Paddies
Factors related to CH4 emissions from rice paddies :
Fertilization
Fertilizer formation
Quantity applied
Application practices
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13. 1. CH4 Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
1. CH4 Production and Emissions
Rice Paddies
Factors related to CH4 emissions from rice paddies :
Organic fertilizer
Addition of rice straw compost
( % increase of CH4 emissions)
Application of fresh rice straw
( % increase of CH4 emissions)
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14. 1. CH4 Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
1. CH4 Production and Emissions
Rice Paddies
Factors related to CH4 emissions from rice paddies :
Rice variety
Rice varieties and CH4 emission
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15. 1. CH4 Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
1. CH4 Production and Emissions
Rice Paddies
Factors related to CH4 emissions from rice paddies :
Plant growth stage.
Differences of CH4 emissions at different growth periods are significant. 78 % of the emissions occurs at the reproduction stage. (Shangguan, 1993)
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16. 1. CH4 Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
1. CH4 Production and Emissions
Rice Paddies
Factors related to CH4 emissions from rice paddies :
Cultivated practices (Ko et al 2000)
TRANSPLANTATION
8-day-old-seedling
30-day-old-seedling
Direct seedling on wet soil
Direct seedling on dry soil
CH4 EMISSIONS
42.4 g CH4 m-2 season-1
40.3 g CH4 m-2 season-1
37.1 g CH4 m-2 season-1
26.9 g CH4 m-2 season-1
CH4 REDUCTION - 5%
13%
37%
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17. 1. CH4 Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
1. CH4 Production and Emissions
Rice Paddies
Factors related to CH4 emissions from rice paddies :
Plowing
Following spring plowing: g CH4 m-2 season-1 emissions
Following fall plowing: g CH4 m-2 season-1 emissions
The increase of CH4 emissions for the field plowed in the spring is due to the degradation of organic matter during the winter. (Ko et al, 2000).
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18. 1. CH4 Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
1. CH4 Production and Emissions
Rice Paddies
Factors related to CH4 emissions from rice paddies
Water regime
With respect to permanent flooding during the dry season
Intermittent irrigation: 15% emission reduction (Adhya et al., 2000)
Mid-season drainage: 43% emission reduction (Corton et al, 2000)
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19. 1. CH4 Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
1. CH4 Production and Emissions
Rice Paddies
Factors related to CH4 emissions from rice paddies
Water regime
In China
- Continuous flooding: Tg C/yr
- Mid-season drainage: Tg C/yr
a decrease of about 5 Tg C/yr with mid-season drainage (Li et al, 2002).
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20. 1. CH4 Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
1. CH4 Production and Emissions
Dryland ecosystems
Because methanogenic bacteria are not active under dry soil conditions, CH4 emissions are generally small. Furthermore, dryland soils can absorb CH4 to some extent. Therefore, the contribution of dryland farming to methane production and emissions is negligible. But the normal digestive processes of animals is very important to CH4 emissions in dryland ecosystems.
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21. 1. CH4 Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
1. CH4 Production and Emissions
Dryland ecosystems
CH4 emissions from the normal digestive processes of animals
- Ruminant animals are the major emitters of methane
- Non-ruminant domesticated animals also produce methane
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22. 1. CH4 Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
1. CH4 Production and Emissions
Dryland ecosystems
The type of digestive system is a major factor.
Ruminant animals have the highest methane emissions among all animal types. Because the capacity of the large intestine to produce methane is lower, non-ruminant domesticated animals have significantly lower methane emissions on a per-animal basis than ruminants
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23. 1. CH4 Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
1. CH4 Production and Emissions
Dryland ecosystems
The animal's feed intake also affects methane emissions.
In general, a higher feed intake leads to higher methane emissions. Feed intake is positively related to animal size, growth rate, and production. Therefore, feed intake varies among animal types as well as among different management practices for individual animal types.
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24. 1. CH4 Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
1. CH4 Production and Emissions
Dryland ecosystems
Methane emissions from Chinese ruminants
Livestock Type
1985
1990 %
Draft Cattle
2805
3343
57.7
Buffalo
1102
1211
19.0
Dairy Cattle 93
153
2.6
Sheep
408
580
10.0
Goats
308
477
8.2
Camels 31 27
0.5
Total
4822
5798
Total CH4 emissions from ruminants in China (Gg) (Dong, et al., 1996)
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25. 1. CH4 Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
1. CH4 Production and Emissions
Dryland ecosystems
The management of livestock manure is also a source of methane emissions
Animal type
1970
1980
1990 %
Dairy cattle
0.00
6.13
23.69
1.9
Draft cattle
43.89
40.34
60.41
4.8
Buffalo
29.46
33.15
38.87
3.1
Swine
574.73
831.92
82.3
Sheep
9.09
11.29
11.72
0.9
Goats
7.86
10.50
12.51
1.0
Horses
11.28
13.11
12.49
Mules/Asses
6.65
7.42
10.40
0.8
Poultry
14.73
51.48
4.1
Total
682.95
968.59
CH4 emission from livestock and poultry manure in China (Gg) (Dong, et al., 1996)
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26. 2. N2O Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
2. N2O Production and Emissions
Rice Paddies
Paddy soils emit nitrous oxide
Main factors that determine N2O emissions in the paddy
field water conditions
fertilization practices
temperature ( at the maturing stage)
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27. 2. N2O Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
2. N2O Production and Emissions
Rice Paddies
Paddy soils emit nitrous oxide
N2O production results from the nitrification and denitrification processes by soil bacteria. Changes in the soil water content can directly impact nitrification and denitrification rates, and thus impact on the N2O production.
N2O production occurs mainly in the spring under anaerobic conditions. Soil ventilation and anaerobic conditions can increase N2O production and emissions. Poor ventilation of the soil is unfavorable to N2O emissions. (Li et al, 2003).
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28. 2. N2O Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
2. N2O Production and Emissions
Rice Paddies
There is a negative relationship between N2O and CH4 emissions
During the early period of field flooding and during the dry spell after rice maturing, large amounts of N2O are released, whereas little CH4 is emitted from the rice paddy. During the flooding period of rice growth, rice paddy emits almost no N2O but large amounts of CH4 (Huang et al., 1999).
Intermittent irrigation can accelerate N2O emissions, but will significantly reduce CH4 ones.
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29. 2. N2O Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
2. N2O Production and Emissions
Dryland ecosystems
Nitrous oxide emissions are significant in dryland ecosystems
Under weak to moderate anaerobic conditions, the nitrification and denitrification processes in the soil can produce and release N2O.
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30. 2. N2O Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
2. N2O Production and Emissions
Dryland ecosystems
Nitrous oxide emissions are significant in dryland ecosystems
90% atmospheric N2O originates from the soil (Feng et al., 1995).
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31. 2. N2O Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
2. N2O Production and Emissions
Dryland ecosystems
The soil environmental factors are susceptible to affect N2O production and emissions.
- Soil temperature
- Soil moisture
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32. 2. N2O Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
2. N2O Production and Emissions
Dryland ecosystems
The soil environmental factors are susceptible to affect N2O production and emissions.
A close and direct relationship between soil N2O emissions and air temperature variations was found.
(N2O emissions increased by 70% when the mean annual air temperature increased from 7.8°C to 11.8°C. (Khalil, et al, 1990) )
Rainfall has a most important impact on the N2O flux on the second day following precipitation; after that, the flux return progressively to normal.
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33. 2. N2O Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
2. N2O Production and Emissions
Dryland ecosystems
The human activities become the most important factor determining the N2O emissions.
- Nature of the crop (type and growth stage)
- Fertilization (including type, particle size and amount of fertilizer, application practices)
- Irrigation
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34. 2. N2O Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
2. N2O Production and Emissions
Dryland ecosystems
The human activities become the most important factor determining the N2O emissions.
- Nature of the crop (type and growth stage)
N2O emissions from corn are the largest among the corn, soybean and wheat crops.
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35. 2. N2O Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
2. N2O Production and Emissions
Dryland ecosystems
The human activities become the most important factor determining the N2O emissions.
- Nature of the crop (type and growth stage)
N2O emissions from various plant organs are contrasting. (Yan et al., 2000)
ROOT
STALK
LEAF
SOYBEAN
249.92
388.66
103.48
CORN
199.58 -
RICE
2.98
μg/(FW g d)
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36. 2. N2O Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
2. N2O Production and Emissions
Dryland ecosystems
The human activities become the most important factor determining the N2O emissions.
- Nature of the crop (type and growth stage)
N2O emissions by corn occur mainly during the growth stage, mainly at the heading/blossoming and maturing ones. Following harvest, root secretions in the soil are used by nitrification and denitrification bacteria, and consequently N2O emissions are still continuing (Xu et al., 1999a).
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37. 2. N2O Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
2. N2O Production and Emissions
Dryland ecosystems
The human activities become the most important factor determining the N2O emissions.
- Nature of the crop (type and growth stage)
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38. 2. N2O Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
2. N2O Production and Emissions
Dryland ecosystems
The human activities become the most important factor determining the N2O emissions.
- Fertilization
The N2O flux above crops is directly related to nitrogen sources. The fertilizer use and application are the most critical factor impacting on N2O emissions. The N fertilizers provide basic material to nitrification and denitrification bacteria, and contribute to increment N2O emissions.
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39. 2. N2O Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
2. N2O Production and Emissions
Dryland ecosystems
The human activities become the most important factor determining the N2O emissions.
- Fertilization
The type and amount of fertilizer : NO3- > NH4+ > urea > (NH4)2CO3 > anhydrous NH3 (Zheng et al., 1996).
The nitrogen fertilizer particle size : N2O emissions are positively related to the N fertilizer particle size (Cheng et al., 1990).
The application methods: the use of organic fertilizer and the surface application of the chemical fertilizer decreased significantly the N2O emissions.
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40. 2. N2O Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
2. N2O Production and Emissions
Dryland ecosystems
The human activities become the most important factor determining the N2O emissions.
- Irrigation
Irrigation modifies the soil physical characteristics, and thereby impacts on the N2O flux.
The impact of irrigation on N2O production and emission occurs mainly through its effect on soil water content.
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41. 2. N2O Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
2. N2O Production and Emissions
Dryland ecosystems
The human activities become the most important factor determining the N2O emissions.
- Irrigation
Dry climatic conditions and low soil water: nitrification process.
High soil water content, e.g. after rainfall: denitrification process.
Moderate soil water content: to the same extent by nitrification and denitrification processes
(Huang et al, 1999).
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42. 2. N2O Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
2. N2O Production and Emissions
Dryland ecosystems
The human activities become the most important factor determining the N2O emissions.
- Irrigation
N2O Emission
(Zheng et al, 1999).
Soil water content
415g.kg-1
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43. 2. N2O Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
2. N2O Production and Emissions
Dryland ecosystems
The management of livestock manure can also produce N2O emissions.
Nitrous oxide is produced as part of the nitrogen cycle through the nitrification and denitrification of the organic nitrogen in livestock manure and urine. But any useful information about nitrous oxide related to animal production (or manure) was not be found in China.
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44. 3. CO2 Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
3. CO2 Production and Emissions
Dryland ecosystems
There are daily variations and seasonal changes of atmospheric CO2 concentration in dry farmland ecosystems and the vertical gradient of CO2 concentration above the crop.
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45. 3. CO2 Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
3. CO2 Production and Emissions
Dryland ecosystems
CO2 flux in the field
- in winter wheat field: mg/(m2.h)
- application of urea fertilizer: mg/(m2.h)
The application of urea fertilizer increases CO2 emission significantly in comparison with not fertilized wheat field .
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46. 3. CO2 Production and Emissions
II. GREENHOUSE GAS EMISSIONS
IN AGROECOSYSTEMS
3. CO2 Production and Emissions
Dryland ecosystems
Agricultural management impacts significantly on soil respiration.
The soil respiration rate is greater under deep tillage and deep plowing than that under minimum tillage or no-till practices.
Increasing the amount of straw returned to the field affects the soil respiration rate in a positive way.
In China, there was 70% of the original organic carbon had lost following deforestation and farming for 15 years. (Zheng et al., 1996).
It is estimated that changes in land use released about 270 Gt CO2 (Huang et al., 1998). Deforestation and soil exploitation will increase CO2 emissions to some extent.
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47. II. GREENHOUSE GAS EMISSIONS IN AGROECOSYSTEMS
4. Use of waste materials in agriculture and their contribution to greenhouse gas emissions
To a large extent, crop products and straws are consumed directly by humans and animals; later on, much of these materials is returned to the environment in the form of waste materials; greenhouse gas emissions to the atmosphere are taking place at that time through physical, chemical and biological processes.
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48. II. GREENHOUSE GAS EMISSIONS IN AGROECOSYSTEMS
4. Use of waste materials in agriculture and their contribution to greenhouse gas emissions
It is estimated that about 1/3 of the total N2O emissions from agriculture is released by animals.
The global CH4 emissions from the animal waste materials amounts to about 28.42Gt (Gou et al., 2000).
CH4 emissions by ruminants account for some 84 % of the total emissions by livestock (Laville et al, 1999).
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49. II. GREENHOUSE GAS EMISSIONS IN AGROECOSYSTEMS
4. Use of waste materials in agriculture and their contribution to greenhouse gas emissions
Straw returned to the field and use of organic fertilizer can also change the soil physical and chemical characteristics, thereby impacting on the activity of methanogenic, nitrification and denitrification bacteria, and thus increase the CH4 and N2O emission fluxes.
Burning of biological agricultural by-products in the developing countries, account for 50 % of the total biological materials being burned. The remaining 50 % of crop waste materials are burned for fuel and energy production.
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50. II. GREENHOUSE GAS EMISSIONS IN AGROECOSYSTEMS
4. Use of waste materials in agriculture and their contribution to greenhouse gas emissions
It is estimated that some 8.7 Gt of dry matter is burned on an annual basis around the world.
Emission Flux
CH4
0.022Gt (Xu et al., 2000)
N2O
Gt (Laville et al, 1999)
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51. Two ways to mitigate greenhouse gas :
III. PRACTICES TO MITIGATE GREENHOUSE GAS EMISSIONS IN AGRICULTURE
Two ways to mitigate greenhouse gas :
to reduce the existing emission sources
to enhance the absorbing capacity of current agricultural sinks as well as creating new ones
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52. III. PRACTICES TO MITIGATE GREENHOUSE GAS EMISSIONS IN AGRICULTURE
1. Mitigating CH4 emissions
Crop production
Changing the environmental factors that determine the activity of methanogenic bacteria through adequate agricultural management practices
Water level control: intermittent irrigation, deep irrigation and constant wetness in the rice paddy
Fertilizer management :substituting a chemical for than an organic fertilizer
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53. III. PRACTICES TO MITIGATE GREENHOUSE GAS EMISSIONS IN AGRICULTURE
1. Mitigating CH4 emissions
Crop production
Changing the environmental factors that determine the activity of methanogenic bacteria through adequate agricultural management practices
Rice variety : ability of rice to release CH4
Use of CH4 inhibitor: application of urease, hydroquinol and dicyandiamide to the soil
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54. III. PRACTICES TO MITIGATE GREENHOUSE GAS EMISSIONS IN AGRICULTURE
1. Mitigating CH4 emissions
B. Animal production
Techniques to be applied for reducing CH4 emissions from ruminants
Improving the forage quality and incorporating nutrition additive in the forage.
Using physical and chemical methods to treat straw in order to improve forage nutrition value.
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55. III. PRACTICES TO MITIGATE GREENHOUSE GAS EMISSIONS IN AGRICULTURE
1. Mitigating CH4 emissions
B. Animal production
Techniques to be applied for reducing CH4 emissions from ruminants
Using growth promoter can reduce CH4 emissions
Changing the gene characteristics of the animals, improving their productivity, increasing the number of twins, decreasing the number of reproductive animals, and using bio-techniques to change the enteric fermentation.
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56. III. PRACTICES TO MITIGATE GREENHOUSE GAS EMISSIONS IN AGRICULTURE
1. Mitigating CH4 emissions
C. Management of agricultural waste
Controlling incomplete burning of biological material through sustainable management of the soil and improving land use:
Improving productivity of existing agricultural land
Extending the fallow season and improving the productivity of the agricultural land
Improving the grassland through better land management
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57. III. PRACTICES TO MITIGATE GREENHOUSE GAS EMISSIONS IN AGRICULTURE
1. Mitigating CH4 emissions
C. Management of agricultural waste
Controlling incomplete burning of biological material through sustainable management of the soil and improving land use:
Returning crop waste material directly to the field
Increasing the amount of energy produced from crop waste material
Changing annual or seasonal crops on marginal land into forest
Monday, November 12, 2018

58. III. PRACTICES TO MITIGATE GREENHOUSE GAS EMISSIONS IN AGRICULTURE
1. Mitigating CH4 emissions
C. Management of agricultural waste
Controlling incomplete burning of biological material through sustainable management of the soil and improving land use:
Improving the grassland through better land management
Returning crop waste material directly to the field
Increasing the amount of energy produced from crop waste material
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59. III. PRACTICES TO MITIGATE GREENHOUSE GAS EMISSIONS IN AGRICULTURE
2. Mitigating N2O emissions
Because the most significant impact on N2O emissions come from irrigation and fertilization, N2O emissions can be reduced through soil water control and rational fertilization.
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60. III. PRACTICES TO MITIGATE GREENHOUSE GAS EMISSIONS IN AGRICULTURE
2. Mitigating N2O emissions
Rational irrigation Rational irrigation according to crop physiological characteristics at different growth stages is essential. It is better to reduce the period of alternate dryness and wetness and the field exposure to air, thereby restraining N2O production and emissions.
Rational fertilization Changing the type of N fertilizer and the amount applied, as well as a rational use of N fertilizer can reduce the N2O emissions.
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61. III. PRACTICES TO MITIGATE GREENHOUSE GAS EMISSIONS IN AGRICULTURE
2. Mitigating N2O emissions
Increasing the carbon supply The addition of organic carbon will result in insufficient oxygen supply and reduce the activity of autotrophic nitrification bacteria, and finally impact on N2O production and emissions.
Use of N2O inhibitor The hydroquinol, dicyandiamide, benzoic acid, nitropyrimidine can significantly restrain N2O emissions (Tenuta et al., 2000; Brown et al., 2000).
Breeding new varieties
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62. III. PRACTICES TO MITIGATE GREENHOUSE GAS EMISSIONS IN AGRICULTURE
3. Mitigating CO2 emissions
The methods for mitigating CO2 emissions in agroecosystems are divided in two sections. One is addressing the decrease of CO2 emissions from existing sources, while the other is proposing to reinforce the absorbing ability of CO2 "sink" as well as creating new CO2 "sinks".
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63. III. PRACTICES TO MITIGATE GREENHOUSE GAS EMISSIONS IN AGRICULTURE
3. Mitigating CO2 emissions
Changing land use Reducing the development of waste land; Using the existing farming land more sustainably; returning fallow land to forest, grassland and fen system to sustain natural ecosystems and the C circulation equilibrium.
Improving cropland management and reducing carbon separation in agroecosystems Using more organic fertilizer; returning more straw back to the cropland; using more perennial crops, and covering crops during the winter, reducing tillage, reducing the fallow period, and transforming barren land to cropland or grassland .
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64. III. PRACTICES TO MITIGATE GREENHOUSE GAS EMISSIONS IN AGRICULTURE
3. Mitigating CO2 emissions
Bio-fuel production
As the bio-fuel results from the assimilation of atmospheric CO2, burning of bio-fuel will not increase atmospheric CO2. It is more favorable to mitigate CO2 emission than burning mineral fuel.
Regions with high production potential should take maximum advantage of fallow land to plant trees and other crops as bio-fuel feedstock.
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65. energy-saving kitchen range
IV. SOME MEASURES OF GREENHOUSE GAS MITIGATION IN CHINA
Improving the water management techniques
Continuous flooding during the rice growing season is changed to mid-season drainage, which greatly decreases CH4 emissions.
Popularization of rebirth energy technology
By the end of 2000, there were about 189 million energy-saving kitchen ranges, eight million door marsh gas pools, and one thousand great and middle urine engineering were in application. The application of them reduced about 15 million tons of CO2 and 210 thousand tons of CH4 emission.
(Wang, 2003)
CO2
CH4
energy-saving kitchen range
84.46%
73.05%
The marsh gas pool
13.63%
21.40%
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66. IV. SOME MEASURES OF GREENHOUSE GAS MITIGATION IN CHINA
Return of farmland to forest or grassland In more recent years, trees and grassland have substituted for annual crops in the western part of China.
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67. V. SUMMARY
CH4 emissions originate mainly from rice paddy fields, and are impacted by soil characteristics, e.g. temperature, water content, pH and Eh conditions, and also by land and crop management, e.g. land use, rice varieties, fertilizer application.
Rice paddy emits not only CH4, but also N2O. However, the N2O emission pattern is quite different from the CH4 one. Field water conditions and fertilization practices are the main factors that determine N2O emissions.
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68. V. SUMMARY
In a farmland ecosystem, CO2 concentration does not increase, because CO2 consumption by photosynthesis is greater than CO2 emission through crop respiration.
The use of waste material in agriculture and breeding development contributes also to greenhouse gas emissions.
In order to mitigate greenhouse gas emissions in agricultural production, the most important measure is to reduce the existing emission sources, and the second one is to enhance the absorbing capacity of current agricultural sinks as well as creating new ones.
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69. V. SUMMARY
Because the effects of these measures on the different greenhouse gases are different, specific practices must be developed and adopted for the different gases.
Monday, November 12, 2018

70. Thank You
Monday, November 12, 2018