Methane

Algorithm

Paddy field

Composite number

Ecology

Biology

Carbon cycle

Materials science

Nitrous oxide

Soil carbon

Carbon fibers

Soil water

Greenhouse gas

Organic chemistry

Mathematics

Agronomy

Environmental science

Soil science

Composite material

Chemistry

Carbon dioxide

Carbon sequestration

Ecosystem

Communications Earth & Environment

Rice paddies account for ~9% or the world’s cropland area and are characterized by environmental conditions promoting soil organic carbon storage, methane emissions and to a lesser extent nitrous oxide emissions. Here, we synthesize data from 612 sites across 51 countries to estimate global carbon stocks in paddy soils and determine the main factors affecting paddy soil carbon storage. Paddy soils (0–100 cm) contain 18 Pg carbon worldwide. Paddy soil carbon stocks decrease with increasing mean annual temperature and soil pH, whereas mean annual precipitation and clay content had minor impacts. Meta-analysis shows that paddy soil carbon stocks can be increased through several management practices. However, greenhouse gas mitigation through paddy soil carbon storage is generally outweighed by increases in methane and nitrous oxide emissions. Our results emphasize the key role of paddies in the global carbon cycle, and the importance of paddy management in minimizing anthropogenic greenhouse gas emissions.

Rice paddy soils are a quantitatively important carbon store according to a global synthesis