LECTURE24

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Gas-gas dari aktivii pertanian: 

Gas-gas dari aktivii pertanian International Panel on Climate Change (IPCC) telah menyarankan supaya kepekatan gas-gas diturunkan sebanyak 5.6% pada tahun 2010 untuk menstabilkan ditahap sekarang. Pengurusan pertanian membekal ~ 30% jumlah methana yang dikeluarkan ke udara – terutama sekali dari sawah padi Tetapi keperluan beras perlu dipertingkatkan untuk menampung keperluan makanan terutama sekali di Asia

Slide2: 

Untuk meningkat pengeluaran beras, tanah perlu diuruskan dengan baik - dengan baja organik dan tak organik Baja organik dalam keadaan terendam (redox)  CH4 (Eh ~ -150-160 Ev) Variety, pembajaan, pengurusan air mempengaruhi pengeluran methana ke udara

Methane Sources (Tg/yr): 

Methane Sources (Tg/yr)

Slide4: 

Effect of Global Warming Scenario by the year 2070 About 3.3 million people may displace through flooding. 800,000 hectares of irrigated rice fields will be inundated 300,000 hectares of coastal fishponds would be lost 25% mangrove forest will be affected Lead to a lost of US$ 113 billion of socio-economic activities. (Gupta, J. 1997)

Slide5: 

Methane (CH4) * 1% increase yr-1 * Current concentration 1730 mg/kg * 30% sources derive from paddy fields * Chemically active in the atmosphere * Influence atmospheric concentration : hydroxyl radicals, ozone, & carbon monoxide. (Cicerone and Oremland, 1988)

Slide6: 

Comparison of annual CH4 emissions (Tg yr-1) from China, India, Indonesia, Philippines, and Thailand predicted in recent years.

Slide7: 

CH4 gas collection Using an automatic gas sampling device Compressed air Gas intake Electric fan Plexiglass chamber

Slide11: 

The CH4 emission pattern of four different rice cultivars during WS of 2001/02

Slide12: 

0 DAT 85 70 15 0 DAT 85 20 30 70 35 0 DAT 85 70 0 DAT 85 70 Treat 1. 5 cm Treat 2. 0 – 1 cm Treat 3. Intermittent irrigation Treat 4. Pulse irrigation

Slide13: 

Water height pattern of treatment 1 (5 cm) Water height pattern of treatment 2 (0-1 cm)

Slide14: 

Water height pattern of intermittent irrigation Water height pattern of pulse irriga-tion

Slide15: 

CH4 emission and redox pattern at 5 cm continuous flooding

Slide16: 

CH4 emission and redox pattern of 0-1 cm continuous flooding Redox potential (mV)

Slide17: 

Redox potential (mV) drain prior to harvest CH4 emission and redox pattern of intermittent irrigation

Slide18: 

CH4 emission and redox pattern of pulse irrigation

Slide19: 

CH4 emission (kg ha-1) and yield of different water management practices during DS 2002 Numbers in the same column and followed by a common letter are not significantly different at P = 0.05 by DNMRT.