Statistical analysis of the major variables controlling methane emission from rice fields

Abstract

Rice cultivation is an important anthropogenic source of atmospheric methane (CH 4 ), the emission of which is affected by management practices. Many field measurements have been conducted in major rice-producing countries in Asia. We compiled a database of CH 4 emissions from rice fields in Asia from peer-reviewed journals. We developed a statistical model to relate CH 4 flux in the rice-growing season to soil properties, water regime in the rice-growing season, water status in the previous season, organic amendment and climate. The statistical results showed that all these variables significantly affected CH 4 flux, and explained 68% of the variability. Organic amendment and water regime in the rice-growing season were the top two controlling variables; climate was the least critical variable. The average CH 4 fluxes from rice fields with single and multiple drainages were 60% and 52% of that from continuously flooded rice fields. The flux from fields that were flooded in the previous season was 2.8 times that from fields previously drained for a long season and 1.9 times that from fields previously drained for a short season. In contrast to the previously reported optimum soil pH of around neutrality, soils with pH of 5.0-5.5 gave the maximum CH 4 emission. The model results demonstrate that application of rice straw at 6 t ha À1 before rice transplanting can increase CH 4 emission by 2.1 times; when applied in the previous season, however, it increases CH 4 emission by only 0.8 times. Default emission factors and scaling factors for different water regimes and organic amendments derived from this work can be used to develop national or regional emission inventories.

Greenhouse gas mitigation by agricultural intensification

“…For both AW expansion scenarios, we assume that the percentages of rain-fed and irrigated systems are the same as in the RW, and that drainage practices and organic amendments are the same in each scenario. These values are derived following the methods and sources used by Yan et al (14,(51)(52)(53) (30).…”

“…As with total cropland, we calculate the amount of land that would be needed to meet RW production values with 1961 yields. We follow the methodology outlined by Yan (14,51) to calculate methane emissions from rice cultivation and GHGs from the burning of rice straw. For both AW expansion scenarios, we assume that the percentages of rain-fed and irrigated systems are the same as in the RW, and that drainage practices and organic amendments are the same in each scenario.…”

Quantifying methane emissions from rice paddies in Northeast China by integrating remote sensing mapping with a biogeochemical model

“…Methane emissions from rice fields are controlled by many factors (Yan et al, 2005). However, some factors could be more sensitive than others.…”

Evaluating the effects of alternate wetting and drying (AWD) on methane and nitrous oxide emissions from a paddy field in Thailand

“…If effectively drained, the emission of CH 4 is expected to be substantially reduced. However, the effectiveness of drainage practices on CH 4 emission reduction depends on the efficiency of water control, soil type, and other cultivation practices (Yan et al 2005;Liang et al 2016). In the current study, practicing AWD in this soil resulted in marginal (p < 0.1) reduction in the CH 4 emission compared to CF by Tukey's HSD test (Table 3).…”