Methane Emissions from Sandy Clay Loam Paddy Soils Under Different Rice Straw Management Strategies

Incorporating rice straw into the soil is increasingly being practised by rice farmers not only in Korea but the world over. It is partly because of the need to boost organic matter stocks of the soils, but it is also in response to the current environmental regulations which strongly decree against the use of thermal treatment to dispose of rice straw. Although this method has come in handy to solve the rice straw waste problem, studies indicate that it also increases levels of methane emissions from the paddy fields. In the current study, we quantified methane emissions from sandy clay loam soils in which the straw was incorporated at different intervals after the rice harvest. There is currently hardly any data concerning methane emissions from this type of soil texture yet soil texture is one of the main factors influencing methane emissions. There were four treatments which included; spreading and ploughing straw into the soil immediately after the autumn harvest (ASS+AP), spreading straw on to the soil after the autumn harvest but ploughing it into the soil in spring (ASS+SP), spreading and ploughing the straw into the soil in the spring season (SSS+SP) and the control with no straw incorporated. All plots were fertilised with equal amounts of NPK. The control plots emitted the lowest amount of methane followed by ASS+AP. Additionally, emissions from ASS+AP and ASS+SP plots decreased in the second year while those from other treatments remained largely unchanged. ASS+AP straw management strategy boosted the soil chemical properties while the effects of other treatments were mostly dreadful. Therefore, ASS+AP can be considered the best management strategy due to lower methane emissions and better soil chemical properties obtained.