Does it matter for methane when rice straw is ploughed into the paddy, shortly before transplanting or long before, under the Intergovernmental Panel on Climate Change 2006 tables?

Yes. In the Intergovernmental Panel on Climate Change (IPCC) 2006 Table 5.14 straw incorporated within 30 days of cultivation has a conversion factor of 1, and straw incorporated more than 30 days before cultivation 0.29. With 5 tonnes per hectare, the methane scaling factor falls from 2.88 to 1.70.

The equation

Equation 5.3 of the IPCC 2006 Guidelines, Volume 4: the organic amendment scaling factor = (1 + the sum of application rate x conversion factor for each amendment) raised to the power 0.59. The application rate is in tonnes per hectare, dry weight for straw and fresh weight for the others. The guide gives an uncertainty range of 0.54 to 0.64 on the exponent.

That factor multiplies the baseline daily methane (CH4) emission of 1.30 kilograms (kg) per hectare per day for a continuously flooded field with no amendments (Table 5.11, error range 0.80 to 2.20).

Conversion factors (Table 5.14)

• Straw incorporated shortly (under 30 days) before cultivation: 1.
• Straw incorporated long (over 30 days) before cultivation: 0.29.
• Compost: 0.05. Farm yard manure: 0.14. Green manure: 0.50.
• Straw application means straw is incorporated into the soil. It does not include straw just placed on the soil surface, nor straw burnt on the field.

Why timing matters

The guide says that after a long fallow following straw incorporation, methane in the next rice season will be less than when straw goes in just before transplanting. That is why it splits the two cases.

Choices you can show a buyer

• Straw ploughed in right after harvest and left to rot through a long fallow is the 0.29 case.
• Straw incorporated at land preparation is the 1 case.
• Straw removed for fodder, baling or fuel adds no straw term in the equation (my reading of Equation 5.3). Straw burnt on the field is outside the table and is counted as burning (see the straw burning answer).
• Keep the date of incorporation in the field record. Without it, a verifier has to assume the 1 case. That is a cautious reading, not a rule in the guide.

5 tonnes of dry straw per hectare, 120-day season, continuously flooded

• Shortly before: (1 + 5 x 1)^0.59 = 6^0.59 = 2.88; daily 1.30 x 2.88 = 3.74 kg CH4 per hectare; season 3.74 x 120 = 449 kg
• Long before: (1 + 5 x 0.29)^0.59 = 2.45^0.59 = 1.70; daily 1.30 x 1.70 = 2.21 kg; season 2.21 x 120 = 265 kg
• Difference: 449 minus 265 = 184 kg CH4 per hectare, 41% lower
• In carbon dioxide equivalent: 184 x 27 = about 4,980 kg per hectare

Straw weight and season length are example values; water regime before and during cultivation are taken as the baseline (scaling factors of 1). 27 is the Sixth Assessment Report (AR6) 100-year warming potential for non-fossil methane. The alternate wetting and drying answer uses a later IPCC edition; do not mix editions in one inventory.

What Senseible does here

Senseible reads fuel invoices and electricity bills into emission records, so diesel for tractors and power for irrigation pumps show up once uploaded. The fertiliser, residue and field figures on this page come from your own farm records.

• Burning paddy straw: emissions per acre
• Alternate wetting and drying methane cut
• Flooded fallow before rice: methane factor

Sources: IPCC 2006 Guidelines, Volume 4, Chapter 5, Section 5.5, Equation 5.3 and Tables 5.11 and 5.14, IPCC Sixth Assessment Report, Working Group I, Chapter 7, Table 7.15 (100-year global warming potential: methane of non-fossil origin 27.0, nitrous oxide 273)

Last reviewed 2026-11-05. Values are from the 2006 edition. If your buyer or programme names a later edition, use its table and say which.