**9. Mitigation of methane emission from paddy field**

CH4 emission increases during flooding condition and decrease when water drain from the field [83]. Therefore, the irrigation system is one of the most vital tools of rice farming and is the most important effort for CH4 mitigation. Thus, the water level is one of the main factors affect the production and emission of CH4 in rice paddy fields. In irrigated rice, a short aeration period at tillering has been shown to increase yield. Single mid-season drainage may reduce seasonal emission rates by about 50% [52]. In a controlled experiment, CH4 emissions can be significantly reduced when the field is drained and dried at mid tillering and

#### *Methane Cycling in Paddy Field: A Global Warming Issue DOI: http://dx.doi.org/10.5772/intechopen.94200*

before harvest [53]. Higher yielding rice genotypes could be viable options for reducing the release of CH4 from paddy fields to the atmosphere [13]. System of Rice Intensification (SRI) is the alternative rice farming for climate change adaptation and mitigates greenhouse gas emission from paddy fields. The study showed that the SRI paddy field with intermittent wetting-drying irrigation reduced CH4 emission by up to 32% [84]. SRI application can save water irrigation up to 28%, 38.5% and 40% in Japan, Iraq and Indonesia, respectively [85]. SRI also reduced greenhouse gas emission that is represented by reducing global warming potential up to 37.5% in Indonesia [86] and 40% in India [87].

The activity of CH4 producing bacteria is inhibited from the oxidizing condition of paddy soil by water management. CH4 emission factor for intermittently flooded paddy fields can decrease by approximately 20% [88]. Water management and organic material management are significant for reducing CH4 emissions from rice paddy fields. Mid-season drainage and intermittent flooding are effective for increasing the productivity and quality of rice as well as reducing CH4 emissions. Mitigation of CH4 emissions from rice paddy fields by water management has huge potential to be marketed. A field experiment in the Philippines showed that direct seeding techniques reduced CH4 emissions by 18% as compared with transplanted rice. Another study, in Japan, showed that global warming potential declined by 42% just by changing the puddle of rice seedlings to zero tillage. Moreover, CH4 emission can be reduced by shifting to more heat-tolerant rice cultivars and by adjusting sowing dates. It will also prevent yield decline due to temperature increases [89]. A multi-criteria evaluation ranking score for CH4 mitigation strategy is been done in Egypt. They found that short duration rice varieties got the highest score. This strategy could be reduced 25% of CH4 emission, reduce 20% of water consumption without any reduction in rice productivity. On the other hand, fertilizer management strategy was in the second-ranking and followed by the midseason drainage [90]. The heat-tolerant improved rice variety with low CH4 emission is a potential mitigation option [91].

### **10. Conclusions**

The most important aim of studies on CH4 emission from paddy fields is the mitigation of global warming and adaptation with climate change. CH4 emission is controlled by several factors such as temperature, soil pH, Eh, rice cultivar, root, rhizosphere, group of methanogens, paddy growing stages and field management.

From the above-mentioned discussion, it is clear how CH4 cycling in paddy fields, also how much CH4 release to atmosphere and leached to ground water and soil.

CH4 can be reduced from paddy field through management practices like, the mid-season drainage, alternate wetting, drying irrigation and using alternative fertilizers have been shown to reduce CH4 emissions from rice paddies and achieve sustain rice production.

By using a combination of feasible mitigation technologies there is great potential to reduce CH4 emission from rice fields and increase rice production. Crop improvement strategies such as breed high yielding and high stress tolerant rice varieties with reduced CH4 emissions will help the CH4 mitigation. These rice varieties should be adaptable to changing climate e.g., the stress and water management conditions.

Cultivation of high-yielding and more heat-tolerant rice cultivars will be a promising approach to reduce CH4 emissions from paddy fields and slowing down global warming.

#### *Agrometeorology*

Future research needs to focus on global paddy field CH4 budgets, climate change adaptation policy and sustainable agriculture technology, creating more disease and heat resistance rice variety.
