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Greenhouse Gas Emissions and Mitigation Measures in Agroecosystem

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).

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Greenhouse Gas Emissions and Mitigation Measures in Agroecosystem

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

  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

  4. INTRODUCTION CO2, CH4 and N2O are the most important greenhouse gases.

  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.

  6. I. GENERAL EMISSIONS CO2 CH4 N2O CO2,CH4, N2OEmissions from Agriculture (Bouwman, 1990)

  7. I. GENERAL EMISSIONS CH4 N2O 12599-20090Gg 70-190Gg CH4, N2OEmissions from Agriculture in China (ADB-GEF-UNEP,1998)

  8. I. GENERAL EMISSIONS N2O 0.096TgN N2OEmissions from Farmland in China in 1990 (Song,1996)

  9. I. GENERAL EMISSIONS CH4 17.5±1.9Tg CH4Emissions from Rice Paddy in China in 1990 (Song,1996)

  10. 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.

  11. II. GREENHOUSE GAS EMISSIONS IN AGROECOSYSTEMS • 1. CH4 Production and Emissions • Rice Paddies • Factors related to CH4emissions from rice paddies: • Field • Soil temperature (in the 0-15 cm layer) • Soil water content • Soil Characteristic

  12. 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

  13. 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 • (23 - 30 % increase of CH4 emissions) • Application of fresh rice straw • (162 - 250 % increase of CH4 emissions)

  14. 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

  15. 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)

  16. 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)

  17. 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:42.0 g CH4 m-2 season-1 emissions • Following fall plowing: 31.3 g CH4 m-2 season-1emissions • 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).

  18. II. GREENHOUSE GAS EMISSIONS IN AGROECOSYSTEMS • 1. CH4 Production and Emissions • Rice Paddies • Factors related to CH4 emissions from rice paddies • Water regime • Withrespect 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)

  19. 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: 6.4-12.0 Tg C/yr • - Mid-season drainage: 1.7-7.8 Tg C/yr • a decrease of about 5 Tg C/yr with mid-season drainage (Li et al, 2002).

  20. 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.

  21. 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

  22. 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

  23. 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.

  24. II. GREENHOUSE GAS EMISSIONS IN AGROECOSYSTEMS • 1. CH4 Production and Emissions • Dryland ecosystems • Methane emissions from Chinese ruminants Total CH4 emissions from ruminants in China (Gg) (Dong, et al., 1996)

  25. 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 CH4 emission from livestock and poultry manure in China (Gg) (Dong, et al., 1996)

  26. II. GREENHOUSE GAS EMISSIONS IN AGROECOSYSTEMS • 2. N2O Production and Emissions • Rice Paddies • Paddy soils emit nitrous oxide • Main factors that determine N2O emissionsin the paddy • field water conditions • fertilization practices • temperature ( at the maturing stage)

  27. 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).

  28. 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.

  29. 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.

  30. 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).

  31. 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

  32. 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.

  33. 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

  34. 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.

  35. 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) μg/(FW g d)

  36. 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).

  37. 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)

  38. 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.

  39. 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.

  40. 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.

  41. 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).

  42. 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

  43. 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.

  44. 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.

  45. II. GREENHOUSE GAS EMISSIONS IN AGROECOSYSTEMS • 3. CO2 Production and Emissions • Dryland ecosystems • CO2 flux in the field • - in winter wheat field: 100-280 mg/(m2.h) • - application of urea fertilizer: 120-400 mg/(m2.h) • The application of urea fertilizer increases CO2 emission significantly in comparison with not fertilized wheat field .

  46. 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.

  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.

  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).

  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.

  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.

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