Climate change and soil C sequestration potential in south-east Asia

Transcription

1 Climate change and soil C sequestration potential in south-east Asia K.R. Islam, Y. Raut, R. Shrestha, and R. Lal State University

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4 Several Arabian scientists (such as al-razi, Ali b. Ridhwan, Ya qub al- Israili, and Ibn al-nafis) dating back from 9th to 13th century addressed environmental pollution especially air and water contamination by human activities. ttp://

5 Squeezing earth for resources to emit C, N, and S based gases: Carbon dioxide, methane, sulfur dioxide, nitrogen oxides, ammonia, smoke, etc.

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9 Loss of SOM as CO2

10 (CDIAC 2008) Total CO 2 emissions ranking 1/2 China/USA 4 India 34 Pakistan 67 Bangladesh 88 Sri Lanka 126 Nepal 162 Maldives 163 Afghanistan 175 Bhutan

11 (CDIAC 2008) Per capita CO 2 emissions (metric ton) 1 Qatar USA Maldives India Pakistan Sri-Lanka Bangladesh Bhutan Nepal Afghanistan 0.01

12 Change in CO 2 emission over time Country Change (M Mg) (%) Global Afghanistan Bangladesh Bhutan India Maldives Nepal Pakistan Sri Lanka Total (CDIAC 2008)

13 Fossil fuel emissions ~ 6.3 billion ton CO 2 /yr Land-use & deforestation ~ 1.9 billion ton CO 2 /yr Global warming potentials Tropospheric Lifetime Global warming Gases (years) potential Carbon dioxide Methane Nitrous oxide CFC s

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15 Evidence of climate change is undeniable Climate change will affect every components and production system on earth for Solutions

16 All the atmospheric CO 2 ~ only 40% of the soil s C holding capacity (Wallace 1984)

17 Land use in South East Asia Country Afghanistan Bangladesh Bhutan India Maldives Nepal Pakistan Sri Lanka Agric. Forested Other area area lands (%)

18 Land use in South east Asia Country Afghanistan Bangladesh Bhutan India Maldives Nepal Pakistan Sri Lanka Arable Permanent Pasture land crops land (%)

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26 What to do?

27 Mulchi and Islam (2002) Since plants are the primary receptors of CO 2, any increase in [CO 2 ] will have positive effects on plants: Increase in photosynthesis Maximize water/nutrient use efficiency Improve plant growth ~40% ~10-60% in shoot production ~ % in root production

28 Natural Vegetation Conventional Tillage Basic differences among No-Tillage + Cover Crop land management systems Continuous porosity Aggregates Forming Litter + roots Steady State Continuous C flux Active Pool Slow Pool Passive Pool SOM Losses Structure disrupted Instable Active MCB and high CO 2 flux Continuous porosity Aeration + mix to Crop Residue Re-aggregation Cover + Crop roots New Steady State Active Pool Slow Pool Passive Pool Continuous C flux

29 Conventional tillage to No-till: Bangladesh In NT system, 30% residues left annually which is equivalent to 0.6 t/ha/yr. If crop residue decomposition is 0.25 then soil C content will be > (0.6*0.75)*(58/100) -> 260 kg/ha/yr If r (0.25) is the soil C that left in the 2 nd yr after the decomposition of the soil C formed in the 1 st yr, then the soil C sequestration after 10 yr will be Y = soil C * (1 - r n )/(1 - r) Y = 0.26*( )/(1-0.75) > 950 kg/ha

30 C sequestration (kg ha -1 yr -1 ) Woodland Rangeland Farmland Land use Afghanistan (Khan and Lal 2007)

31 30 Total C (Mg ha -1 ) Protected forest (2000) Initial (1982) Degraded forest (2000) Soil depth (cm) Bangladesh (Islam and Weil 2000) Total C (Mg ha -1 ) Natural forest Reforested Grassland Cultivated

32 Total C (Mg ha -1 ) Initial ('75-78) Control ('95-98) NPK ('75-78) NPK+FM ('75-78) 2 0 India (Lal 2004) R-R M-W F-R-W Cassav Cropping systems C sequestration (kg ha -1 yr - 1) Water Wind Irrig Rainfed Saline Degraded soils

33 20 Hill- warm tempearte in Nepal Total C (Mg ha-1) cm cm cm 14 Terai- Sub-tropical in Nepal 0 Reforested Initial 0-yr Cult. 50-yr Management systems Nepal (Maskey et al. 2000) Total C (Mg ha-1) Uncult. 50-yr Initial 0-yr 0-15 cm cm cm Cult. 50-yr Management systems

34 80 Total C (Mg ha-1) C sequestration = 9.3 Mg ha-1 y Time (year) Pakistan (Khan and Lal 2005) C sequestration (kg ha -1 yr -1 ) Farm manure Crop residue Mung bean N fertilization (kg ha -1 )

35 C sequestration (kg ha -1 yr - 1) Afghanistan Bangladesh Bhutan India Maldives Nepal Pakistan Sri Lanka Lal

36 Total potential (Tg C) Afghanistan Bangladesh Bhutan India Maldives Nepal Pakistan Sri Lanka Total Lal

37 Recommended practices for soil C sequestration Reduced tillage/crop rotation e.g. No-till wheat Organic amendments e.g. Green manuring e.g. Biofertilization e.g. Biosolids/composts/manures Chemical fertilization/liming e.g. NPK with micronutrients Mulching/Residue Management Agroforestry/Social forestry Afforestation/Reforestation

38 Climate Change Song or Cry! Who Cares?