Impact of Management Practices on Methane Emissions from Paddy Grown on Mineral Soil over Peat in Central Hokkaido, Japan

Habib Naser,Osamu Nagata,Sarmin Sultana,Ryusuke Hatano

doi:10.3390/atmos9060212

Abstract

This study was carried out at Kita-mura near Bibai located in central Hokkaido, Japan, with the intention of investigating the effects of different agronomical managements on CH4 emissions from paddy fields on mineral soil over peat under farmers’ actual management conditions in the snowy temperate region. Four fields were studied, including two fields with twice drainage (D1-M and D2-M) and also a single-drainage field (D3-S) under annual single-cropping and a paddy-fallow-paddy crop rotation as their systems. The other field was under single cropping annual with continuous flooding (CF-R) in the pattern of soybean (upland crop)-fallow-paddy. The mineral-soil thickness of these soil-dressed peatland fields varied from 20 to 47 cm. The amount of crop residues leftover in the fields ranged from 277 to 751 g dry matter m−2. Total CH4 emissions ranged from 25.3 to 116 g CH4-C m−2 per growing season. There was a significant relationship between crop-residue carbon (C) and total CH4 emissions during the rice-growing season. Methane fluxes from paddy soils had a strong interaction between readily available C source for methanogens and anaerobic conditions created by water management. Despite the differences in water regime and soil type, the average values of straw’s efficiency on CH4 production in this study were significantly higher than those of southern Japan and statistically identical with central Hokkaido. Our results suggest that the environmental conditions of central Hokkaido in association with crop-residue management had a significant influence on CH4 emission from paddy fields on mineral soil over peat. Rotation soybean (upland)-to-paddy followed by drainage-twice practices also largely reduces CH4 emission. However, mineral-soil dressing on peat could have a significant impact on suppression of CH4 emissions from beneath the peat reservoir.

Highlights

The increased atmospheric concentration of greenhouse gases (GHGs), including carbon dioxide (CO2 ), methane (CH4 ), and nitrous oxide (N2 O), are responsible for past, current, and predicted future global warming by substantially increasing the greenhouse effect [1]
It is important to understand the change in magnitude of GHG fluxes from soil.These fluxes are either by-products, intermediates, or end-products of soil-related microbial processes involved in C and N dynamics in soils [2]
It may be concluded that rice-straw management in paddy fields on mineral soil over peat significantly regulates CH4 emission

Summary

Introduction

The increased atmospheric concentration of greenhouse gases (GHGs), including carbon dioxide (CO2 ), methane (CH4 ), and nitrous oxide (N2 O), are responsible for past, current, and predicted future global warming by substantially increasing the greenhouse effect [1]. The paddy field is considered to be an important anthropogenic CH4 emission source [3]. Methane has been reported to account for 95% of the total carbon dioxide-equivalent (CO2 -equivalent) emissions from paddy fields [4]. The annual CH4 emission from rice paddies has been estimated to be 36 Tg year−1 , contributing approximately 18% of the total anthropogenic CH4 emission to the atmosphere [6]. Methane emissions in rice fields can be quite different in different sites, and in seasonal and management types [7]. Irrigated rice is one of the few major CH4 sources that is manageable, and is, likely to be a critical focus of mitigation efforts

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Discussion

Conclusion