If my paddy stays flooded between crops, how much more methane does the Intergovernmental Panel on Climate Change 2006 method count than for a dry fallow or a dry pre-season?

Table 5.13 of the Intergovernmental Panel on Climate Change (IPCC) 2006 Guidelines scales the season by 1.90 after more than 30 days flooded before planting, 1 after a dry pre-season under 180 days and 0.68 after a dry fallow over 180 days. So flooding counts nearly double a dry pre-season and 2.8 times a dry fallow.

The three cases (Table 5.13)

• Non-flooded pre-season under 180 days, common under double cropping of rice: 1 (error range 0.88 to 1.14).
• Non-flooded pre-season over 180 days, for example one rice crop after a dry fallow: 0.68 (0.58 to 0.80).
• Flooded pre-season, where the minimum flooding interval is 30 days: 1.90 (1.65 to 2.18). Flooding shorter than 30 days, usually to prepare the soil for ploughing, is not counted in this category.
• If you have no data on the pre-season, the aggregated case factor is 1.22 (1.07 to 1.40).

Where it goes in the sum

Equation 5.2: adjusted daily emission factor = baseline 1.30 kilograms (kg) of methane (CH4) per hectare per day x water regime scaling factor during cultivation x the pre-season factor above x the organic amendment factor x soil and cultivar factor where you hold one. Then multiply by days of cultivation and hectares (Equation 5.1).

Emissions outside the growing season

The guide adds a completeness point: if soil submergence is not limited to the rice growing season, emissions outside the season, for example from a flooded fallow, should be included. Table 5.13 gives the scaling for the next crop; the table footnote sends you to that completeness section for the pre-season emission itself. That bullet cites published studies and prints no factor.

What to keep on file

• Dates the field was last flooded and drained before planting, by plot.
• Crop calendar for each of the two seasons if you grow two. The guide says rice crops grown in the same year should be reported independently.

One hectare, 120-day season, continuous flooding, no amendments

• Dry pre-season under 180 days: 1.30 x 1 x 120 = 156 kg CH4 per hectare
• Dry fallow over 180 days: 1.30 x 0.68 x 120 = 106 kg
• Flooded pre-season over 30 days: 1.30 x 1.90 x 120 = 296 kg
• In carbon dioxide equivalent (CO2e) at 27: 4,212 kg, 2,864 kg and 8,003 kg per hectare

Season length is an example value. 27 is the Sixth Assessment Report (AR6) 100-year warming potential for non-fossil methane.

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.

• Rice straw ploughed in early or late
• Rainfed or irrigated paddy: methane factor
• Alternate wetting and drying methane cut

Sources: IPCC 2006 Guidelines, Volume 4, Chapter 5, Section 5.5, Equations 5.1 and 5.2 and Tables 5.11 and 5.13, 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. Factors are from the 2006 edition. Keep the same edition across years, and check the table if your programme names a later one.