Unexpected high mitigation of methane emission via short-term aerobic digestion of cover crop biomass before flooding in rice paddy

Mr Jin Ho Lee1,2, Ms Hyeon Ji Song1, Ms Mun Hyeong Park1, Mr Pill Joo Kim1,2

1Division of Applied Life Science (BK 21+ Program), Gyeongsang National University, Jinju, South Korea, 2Institute of Agriculture and Life Sciences, Gyeongsang National University, Jinju, South Korea

Soil organic matter (SOM) is used as an important indicator of soil quality and a countermeasure to mitigate global warming. To increase SOM stock, cover cropping and its biomass incorporation are strongly suggested in mono-rice paddy. However, since biomass application significantly increased greenhouse gas emission (GHG), in particular, methane (CH4), during the flooded rice cultivation, its positive effect is confronting with the negative environmental problem. We hypothesized that the short-term aerobic digestion of cover crop biomass under the dried soil before flooding might degrade labile organic matter into carbon dioxide (CO2), and then reduce CH4 production during the flooded rice cultivation. In order to evaluate the feasibility of the short-term aerobic digestion of amended biomass on reducing CH4 emission in a rice paddy, the mixture of barley and hairy vetch biomass was added inner dried soil with different time intervals from 0 to 30 days before flooding, and then CH4 emission rates were monitored. In the two months’ incubation test, more than 10 days of aerobic digestion before flooding significantly decreased CH4 flux by 88-98% over the control, in which soil was immediately flooded without aerobic digestion. In the field test, similar results were observed. Only 10 days of aerobic digestion after biomass addition under the dried soil condition reduced seasonal CH4 flux by approximately 60% over the control. This reduction effect was slightly increased by extending the aerobic digestion period. In contrast, rice productivities were not significantly different from 0 to 30 days of pre-aerobic digestion. As a result, more than 10 days of aerobic digestion before flooding decreased CH4 intensity which means the yield-scaled CH4 emission by 60% over the control. In conclusion, the pre-aerobic digestion of cover crop biomass before flooding can be good soil management to reduce CH4 emission without productivity damage in rice paddy soil.


Biography:

I earned B.Sc. and M.Sc. from Gyeongsang national university, Korea. Our team has developed effective soil management to enhance soil organic carbon stock without crop productivity losses.

SOIL ORGANIC MATTER

7th International Symposium
Soil Organic Matter

6 – 11 October 2019

Hilton Adelaide

Adelaide, South Australia

Australia

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