Good try, but it doesn’t pass the ‘smell test’.
Methane levels have been much, much higher, > 250 years ago, but still is only .0000034% of the atmospeheric volume.
Methane comes from many chemical reactions - not all of them organic. “growing rice” is insignificant.
Please go back and do a little more research, and don’t be sucked in by carefully crafted “plausibility”
Methane is a trace gas that has more than doubled in the atmosphere since pre-industrial times, due mainly to human activities. After water vapor and carbon dioxide, it is the most important greenhouse gas and accounts for approximately 20 percent of the human-influenced greenhouse gas warming potential.
While methane is emitted to the atmosphere by some natural sources, such as wetlands, more than 70 percent of total emissions are due to human activities including fossil fuel production and use, intestinal gas from livestock and farm animals, and cultivation of rice paddies. Since many methane sources are the result of human activities, increased industrialization in developing countries and stepped up global food demand could result in increased emissions in the future.